tcp: move features to separate files

Type: refactor

Signed-off-by: Florin Coras <fcoras@cisco.com>
Change-Id: Ia477b8dba9266f47907967e363c11048e5cd95ab

17 files changed, 3127 insertions, 2946 deletions

diff --git a/src/vnet/CMakeLists.txt b/src/vnet/CMakeLists.txt
index 1574c3daa70..21780e2beb4 100644
--- a/src/vnet/CMakeLists.txt
+++ b/src/vnet/CMakeLists.txt
@@ -659,9 +659,11 @@ list(APPEND VNET_SOURCES
   tcp/tcp_output.c
   tcp/tcp_input.c
   tcp/tcp_newreno.c
-  tcp/tcp_cubic.c
   tcp/tcp_bt.c
+  tcp/tcp_cli.c
+  tcp/tcp_cubic.c
   tcp/tcp_debug.c
+  tcp/tcp_sack.c
   tcp/tcp.c
 )
 
@@ -674,7 +676,12 @@ list(APPEND VNET_MULTIARCH_SOURCES
 list(APPEND VNET_HEADERS
   tcp/tcp_packet.h
   tcp/tcp_timer.h
+  tcp/tcp_bt.h
+  tcp/tcp_cc.h
   tcp/tcp_debug.h
+  tcp/tcp_inlines.h
+  tcp/tcp_sack.h
+  tcp/tcp_types.h
   tcp/tcp.h
   tcp/tcp_error.def
 )
diff --git a/src/vnet/tcp/tcp.c b/src/vnet/tcp/tcp.c
index a1d774dc89b..2ac938a1b1e 100644
--- a/src/vnet/tcp/tcp.c
+++ b/src/vnet/tcp/tcp.c
@@ -19,11 +19,10 @@
  */
 
 #include <vnet/tcp/tcp.h>
+#include <vnet/tcp/tcp_inlines.h>
 #include <vnet/session/session.h>
 #include <vnet/fib/fib.h>
 #include <vnet/dpo/load_balance.h>
-#include <vnet/dpo/receive_dpo.h>
-#include <vnet/ip-neighbor/ip_neighbor.h>
 #include <math.h>
 
 tcp_main_t tcp_main;
@@ -707,51 +706,6 @@ tcp_connection_init_vars (tcp_connection_t * tc)
   tc->start_ts = tcp_time_now_us (tc->c_thread_index);
 }
 
-void
-tcp_init_w_buffer (tcp_connection_t * tc, vlib_buffer_t * b, u8 is_ip4)
-{
-  tcp_header_t *th = tcp_buffer_hdr (b);
-
-  tc->c_lcl_port = th->dst_port;
-  tc->c_rmt_port = th->src_port;
-  tc->c_is_ip4 = is_ip4;
-
-  if (is_ip4)
-    {
-      ip4_header_t *ip4 = vlib_buffer_get_current (b);
-      tc->c_lcl_ip4.as_u32 = ip4->dst_address.as_u32;
-      tc->c_rmt_ip4.as_u32 = ip4->src_address.as_u32;
-    }
-  else
-    {
-      ip6_header_t *ip6 = vlib_buffer_get_current (b);
-      clib_memcpy_fast (&tc->c_lcl_ip6, &ip6->dst_address,
-			sizeof (ip6_address_t));
-      clib_memcpy_fast (&tc->c_rmt_ip6, &ip6->src_address,
-			sizeof (ip6_address_t));
-    }
-
-  tc->irs = vnet_buffer (b)->tcp.seq_number;
-  tc->rcv_nxt = vnet_buffer (b)->tcp.seq_number + 1;
-  tc->rcv_las = tc->rcv_nxt;
-  tc->sw_if_index = vnet_buffer (b)->sw_if_index[VLIB_RX];
-  tc->snd_wl1 = vnet_buffer (b)->tcp.seq_number;
-  tc->snd_wl2 = vnet_buffer (b)->tcp.ack_number;
-
-  /* RFC1323: TSval timestamps sent on {SYN} and {SYN,ACK}
-   * segments are used to initialize PAWS. */
-  if (tcp_opts_tstamp (&tc->rcv_opts))
-    {
-      tc->tsval_recent = tc->rcv_opts.tsval;
-      tc->tsval_recent_age = tcp_time_now ();
-    }
-
-  if (tcp_opts_wscale (&tc->rcv_opts))
-    tc->snd_wscale = tc->rcv_opts.wscale;
-
-  tc->snd_wnd = clib_net_to_host_u16 (th->window) << tc->snd_wscale;
-}
-
 static int
 tcp_alloc_custom_local_endpoint (tcp_main_t * tm, ip46_address_t * lcl_addr,
 				 u16 * lcl_port, u8 is_ip4)
@@ -831,256 +785,6 @@ tcp_session_open (transport_endpoint_cfg_t * rmt)
   return tc->c_c_index;
 }
 
-const char *tcp_fsm_states[] = {
-#define _(sym, str) str,
-  foreach_tcp_fsm_state
-#undef _
-};
-
-u8 *
-format_tcp_state (u8 * s, va_list * args)
-{
-  u32 state = va_arg (*args, u32);
-
-  if (state < TCP_N_STATES)
-    s = format (s, "%s", tcp_fsm_states[state]);
-  else
-    s = format (s, "UNKNOWN (%d (0x%x))", state, state);
-  return s;
-}
-
-const char *tcp_cfg_flags_str[] = {
-#define _(sym, str) str,
-  foreach_tcp_cfg_flag
-#undef _
-};
-
-static u8 *
-format_tcp_cfg_flags (u8 * s, va_list * args)
-{
-  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
-  int i, last = -1;
-
-  for (i = 0; i < TCP_CFG_N_FLAG_BITS; i++)
-    if (tc->cfg_flags & (1 << i))
-      last = i;
-  for (i = 0; i < last; i++)
-    {
-      if (tc->cfg_flags & (1 << i))
-	s = format (s, "%s, ", tcp_cfg_flags_str[i]);
-    }
-  if (last >= 0)
-    s = format (s, "%s", tcp_cfg_flags_str[last]);
-  return s;
-}
-
-const char *tcp_connection_flags_str[] = {
-#define _(sym, str) str,
-  foreach_tcp_connection_flag
-#undef _
-};
-
-static u8 *
-format_tcp_connection_flags (u8 * s, va_list * args)
-{
-  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
-  int i, last = -1;
-
-  for (i = 0; i < TCP_CONN_N_FLAG_BITS; i++)
-    if (tc->flags & (1 << i))
-      last = i;
-  for (i = 0; i < last; i++)
-    {
-      if (tc->flags & (1 << i))
-	s = format (s, "%s, ", tcp_connection_flags_str[i]);
-    }
-  if (last >= 0)
-    s = format (s, "%s", tcp_connection_flags_str[last]);
-  return s;
-}
-
-const char *tcp_conn_timers[] = {
-#define _(sym, str) str,
-  foreach_tcp_timer
-#undef _
-};
-
-static u8 *
-format_tcp_timers (u8 * s, va_list * args)
-{
-  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
-  int i, last = -1;
-
-  for (i = 0; i < TCP_N_TIMERS; i++)
-    if (tc->timers[i] != TCP_TIMER_HANDLE_INVALID)
-      last = i;
-
-  for (i = 0; i < last; i++)
-    {
-      if (tc->timers[i] != TCP_TIMER_HANDLE_INVALID)
-	s = format (s, "%s,", tcp_conn_timers[i]);
-    }
-
-  if (last >= 0)
-    s = format (s, "%s", tcp_conn_timers[i]);
-
-  return s;
-}
-
-static u8 *
-format_tcp_congestion_status (u8 * s, va_list * args)
-{
-  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
-  if (tcp_in_recovery (tc))
-    s = format (s, "recovery");
-  else if (tcp_in_fastrecovery (tc))
-    s = format (s, "fastrecovery");
-  else
-    s = format (s, "none");
-  return s;
-}
-
-static i32
-tcp_rcv_wnd_available (tcp_connection_t * tc)
-{
-  return (i32) tc->rcv_wnd - (tc->rcv_nxt - tc->rcv_las);
-}
-
-static u8 *
-format_tcp_congestion (u8 * s, va_list * args)
-{
-  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
-  u32 indent = format_get_indent (s), prr_space = 0;
-
-  s = format (s, "%U ", format_tcp_congestion_status, tc);
-  s = format (s, "algo %s cwnd %u ssthresh %u bytes_acked %u\n",
-	      tc->cc_algo->name, tc->cwnd, tc->ssthresh, tc->bytes_acked);
-  s = format (s, "%Ucc space %u prev_cwnd %u prev_ssthresh %u\n",
-	      format_white_space, indent, tcp_available_cc_snd_space (tc),
-	      tc->prev_cwnd, tc->prev_ssthresh);
-  s = format (s, "%Usnd_cong %u dupack %u limited_tx %u\n",
-	      format_white_space, indent, tc->snd_congestion - tc->iss,
-	      tc->rcv_dupacks, tc->limited_transmit - tc->iss);
-  s = format (s, "%Urxt_bytes %u rxt_delivered %u rxt_head %u rxt_ts %u\n",
-	      format_white_space, indent, tc->snd_rxt_bytes,
-	      tc->rxt_delivered, tc->rxt_head - tc->iss,
-	      tcp_time_now_w_thread (tc->c_thread_index) - tc->snd_rxt_ts);
-  if (tcp_in_fastrecovery (tc))
-    prr_space = tcp_fastrecovery_prr_snd_space (tc);
-  s = format (s, "%Uprr_start %u prr_delivered %u prr space %u\n",
-	      format_white_space, indent, tc->prr_start - tc->iss,
-	      tc->prr_delivered, prr_space);
-  return s;
-}
-
-static u8 *
-format_tcp_stats (u8 * s, va_list * args)
-{
-  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
-  u32 indent = format_get_indent (s);
-  s = format (s, "in segs %lu dsegs %lu bytes %lu dupacks %u\n",
-	      tc->segs_in, tc->data_segs_in, tc->bytes_in, tc->dupacks_in);
-  s = format (s, "%Uout segs %lu dsegs %lu bytes %lu dupacks %u\n",
-	      format_white_space, indent, tc->segs_out,
-	      tc->data_segs_out, tc->bytes_out, tc->dupacks_out);
-  s = format (s, "%Ufr %u tr %u rxt segs %lu bytes %lu duration %.3f\n",
-	      format_white_space, indent, tc->fr_occurences,
-	      tc->tr_occurences, tc->segs_retrans, tc->bytes_retrans,
-	      tcp_time_now_us (tc->c_thread_index) - tc->start_ts);
-  s = format (s, "%Uerr wnd data below %u above %u ack below %u above %u",
-	      format_white_space, indent, tc->errors.below_data_wnd,
-	      tc->errors.above_data_wnd, tc->errors.below_ack_wnd,
-	      tc->errors.above_ack_wnd);
-  return s;
-}
-
-static u8 *
-format_tcp_vars (u8 * s, va_list * args)
-{
-  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
-  s = format (s, " index: %u cfg: %U flags: %U timers: %U\n", tc->c_c_index,
-	      format_tcp_cfg_flags, tc, format_tcp_connection_flags, tc,
-	      format_tcp_timers, tc);
-  s = format (s, " snd_una %u snd_nxt %u snd_una_max %u",
-	      tc->snd_una - tc->iss, tc->snd_nxt - tc->iss,
-	      tc->snd_una_max - tc->iss);
-  s = format (s, " rcv_nxt %u rcv_las %u\n",
-	      tc->rcv_nxt - tc->irs, tc->rcv_las - tc->irs);
-  s = format (s, " snd_wnd %u rcv_wnd %u rcv_wscale %u ",
-	      tc->snd_wnd, tc->rcv_wnd, tc->rcv_wscale);
-  s = format (s, "snd_wl1 %u snd_wl2 %u\n", tc->snd_wl1 - tc->irs,
-	      tc->snd_wl2 - tc->iss);
-  s = format (s, " flight size %u out space %u rcv_wnd_av %u",
-	      tcp_flight_size (tc), tcp_available_output_snd_space (tc),
-	      tcp_rcv_wnd_available (tc));
-  s = format (s, " tsval_recent %u\n", tc->tsval_recent);
-  s = format (s, " tsecr %u tsecr_last_ack %u tsval_recent_age %u",
-	      tc->rcv_opts.tsecr, tc->tsecr_last_ack,
-	      tcp_time_now () - tc->tsval_recent_age);
-  s = format (s, " snd_mss %u\n", tc->snd_mss);
-  s = format (s, " rto %u rto_boff %u srtt %u us %.3f rttvar %u rtt_ts %.4f",
-	      tc->rto, tc->rto_boff, tc->srtt, tc->mrtt_us * 1000, tc->rttvar,
-	      tc->rtt_ts);
-  s = format (s, " rtt_seq %u\n", tc->rtt_seq - tc->iss);
-  s = format (s, " next_node %u opaque 0x%x fib_index %u\n",
-	      tc->next_node_index, tc->next_node_opaque, tc->c_fib_index);
-  s = format (s, " cong:   %U", format_tcp_congestion, tc);
-
-  if (tc->state >= TCP_STATE_ESTABLISHED)
-    {
-      s = format (s, " sboard: %U\n", format_tcp_scoreboard, &tc->sack_sb,
-		  tc);
-      s = format (s, " stats: %U\n", format_tcp_stats, tc);
-    }
-  if (vec_len (tc->snd_sacks))
-    s = format (s, " sacks tx: %U\n", format_tcp_sacks, tc);
-
-  return s;
-}
-
-u8 *
-format_tcp_connection_id (u8 * s, va_list * args)
-{
-  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
-  if (!tc)
-    return s;
-  if (tc->c_is_ip4)
-    {
-      s = format (s, "[%d:%d][%s] %U:%d->%U:%d", tc->c_thread_index,
-		  tc->c_s_index, "T", format_ip4_address, &tc->c_lcl_ip4,
-		  clib_net_to_host_u16 (tc->c_lcl_port), format_ip4_address,
-		  &tc->c_rmt_ip4, clib_net_to_host_u16 (tc->c_rmt_port));
-    }
-  else
-    {
-      s = format (s, "[%d:%d][%s] %U:%d->%U:%d", tc->c_thread_index,
-		  tc->c_s_index, "T", format_ip6_address, &tc->c_lcl_ip6,
-		  clib_net_to_host_u16 (tc->c_lcl_port), format_ip6_address,
-		  &tc->c_rmt_ip6, clib_net_to_host_u16 (tc->c_rmt_port));
-    }
-
-  return s;
-}
-
-u8 *
-format_tcp_connection (u8 * s, va_list * args)
-{
-  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
-  u32 verbose = va_arg (*args, u32);
-
-  if (!tc)
-    return s;
-  s = format (s, "%-50U", format_tcp_connection_id, tc);
-  if (verbose)
-    {
-      s = format (s, "%-15U", format_tcp_state, tc->state);
-      if (verbose > 1)
-	s = format (s, "\n%U", format_tcp_vars, tc);
-    }
-
-  return s;
-}
-
 static u8 *
 format_tcp_session (u8 * s, va_list * args)
 {
@@ -1119,100 +823,6 @@ format_tcp_half_open_session (u8 * s, va_list * args)
   return format (s, "%U", format_tcp_connection_id, tc);
 }
 
-u8 *
-format_tcp_sacks (u8 * s, va_list * args)
-{
-  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
-  sack_block_t *sacks = tc->snd_sacks;
-  sack_block_t *block;
-  int i, len = 0;
-
-  len = vec_len (sacks);
-  for (i = 0; i < len - 1; i++)
-    {
-      block = &sacks[i];
-      s = format (s, " start %u end %u\n", block->start - tc->irs,
-		  block->end - tc->irs);
-    }
-  if (len)
-    {
-      block = &sacks[len - 1];
-      s = format (s, " start %u end %u", block->start - tc->irs,
-		  block->end - tc->irs);
-    }
-  return s;
-}
-
-u8 *
-format_tcp_rcv_sacks (u8 * s, va_list * args)
-{
-  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
-  sack_block_t *sacks = tc->rcv_opts.sacks;
-  sack_block_t *block;
-  int i, len = 0;
-
-  len = vec_len (sacks);
-  for (i = 0; i < len - 1; i++)
-    {
-      block = &sacks[i];
-      s = format (s, " start %u end %u\n", block->start - tc->iss,
-		  block->end - tc->iss);
-    }
-  if (len)
-    {
-      block = &sacks[len - 1];
-      s = format (s, " start %u end %u", block->start - tc->iss,
-		  block->end - tc->iss);
-    }
-  return s;
-}
-
-static u8 *
-format_tcp_sack_hole (u8 * s, va_list * args)
-{
-  sack_scoreboard_hole_t *hole = va_arg (*args, sack_scoreboard_hole_t *);
-  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
-  if (tc)
-    s = format (s, "  [%u, %u]", hole->start - tc->iss, hole->end - tc->iss);
-  else
-    s = format (s, "  [%u, %u]", hole->start, hole->end);
-  return s;
-}
-
-u8 *
-format_tcp_scoreboard (u8 * s, va_list * args)
-{
-  sack_scoreboard_t *sb = va_arg (*args, sack_scoreboard_t *);
-  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
-  sack_scoreboard_hole_t *hole;
-  u32 indent = format_get_indent (s);
-
-  s = format (s, "sacked %u last_sacked %u lost %u last_lost %u"
-	      " rxt_sacked %u\n",
-	      sb->sacked_bytes, sb->last_sacked_bytes, sb->lost_bytes,
-	      sb->last_lost_bytes, sb->rxt_sacked);
-  s = format (s, "%Ulast_delivered %u high_sacked %u is_reneging %u\n",
-	      format_white_space, indent, sb->last_bytes_delivered,
-	      sb->high_sacked - tc->iss, sb->is_reneging);
-  s = format (s, "%Ucur_rxt_hole %u high_rxt %u rescue_rxt %u",
-	      format_white_space, indent, sb->cur_rxt_hole,
-	      sb->high_rxt - tc->iss, sb->rescue_rxt - tc->iss);
-
-  hole = scoreboard_first_hole (sb);
-  if (hole)
-    s = format (s, "\n%Uhead %u tail %u %u holes:\n%U", format_white_space,
-		indent, sb->head, sb->tail, pool_elts (sb->holes),
-		format_white_space, indent);
-
-  while (hole)
-    {
-      s = format (s, "%U", format_tcp_sack_hole, hole, tc);
-      hole = scoreboard_next_hole (sb, hole);
-    }
-
-  return s;
-}
-
 static transport_connection_t *
 tcp_session_get_transport (u32 conn_index, u32 thread_index)
 {
@@ -1813,7 +1423,6 @@ tcp_init (vlib_main_t * vm)
   transport_register_protocol (TRANSPORT_PROTO_TCP, &tcp_proto,
 			       FIB_PROTOCOL_IP6, tcp6_output_node.index);
 
-  tcp_api_reference ();
   tcp_configuration_init ();
 
   tm->cc_algo_by_name = hash_create_string (0, sizeof (uword));
@@ -1823,666 +1432,6 @@ tcp_init (vlib_main_t * vm)
 
 VLIB_INIT_FUNCTION (tcp_init);
 
-uword
-unformat_tcp_cc_algo (unformat_input_t * input, va_list * va)
-{
-  tcp_cc_algorithm_type_e *result = va_arg (*va, tcp_cc_algorithm_type_e *);
-  tcp_main_t *tm = &tcp_main;
-  char *cc_algo_name;
-  u8 found = 0;
-  uword *p;
-
-  if (unformat (input, "%s", &cc_algo_name)
-      && ((p = hash_get_mem (tm->cc_algo_by_name, cc_algo_name))))
-    {
-      *result = *p;
-      found = 1;
-    }
-
-  vec_free (cc_algo_name);
-  return found;
-}
-
-uword
-unformat_tcp_cc_algo_cfg (unformat_input_t * input, va_list * va)
-{
-  tcp_main_t *tm = vnet_get_tcp_main ();
-  tcp_cc_algorithm_t *cc_alg;
-  unformat_input_t sub_input;
-  int found = 0;
-
-  vec_foreach (cc_alg, tm->cc_algos)
-  {
-    if (!unformat (input, cc_alg->name))
-      continue;
-
-    if (cc_alg->unformat_cfg
-	&& unformat (input, "%U", unformat_vlib_cli_sub_input, &sub_input))
-      {
-	if (cc_alg->unformat_cfg (&sub_input))
-	  found = 1;
-      }
-  }
-  return found;
-}
-
-static clib_error_t *
-tcp_config_fn (vlib_main_t * vm, unformat_input_t * input)
-{
-  u32 cwnd_multiplier, tmp_time;
-  uword memory_size;
-
-  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
-    {
-      if (unformat (input, "preallocated-connections %d",
-		    &tcp_cfg.preallocated_connections))
-	;
-      else if (unformat (input, "preallocated-half-open-connections %d",
-			 &tcp_cfg.preallocated_half_open_connections))
-	;
-      else if (unformat (input, "buffer-fail-fraction %f",
-			 &tcp_cfg.buffer_fail_fraction))
-	;
-      else if (unformat (input, "max-rx-fifo %U", unformat_memory_size,
-			 &memory_size))
-	{
-	  if (memory_size >= 0x100000000)
-	    {
-	      return clib_error_return
-		(0, "max-rx-fifo %llu (0x%llx) too large", memory_size,
-		 memory_size);
-	    }
-	  tcp_cfg.max_rx_fifo = memory_size;
-	}
-      else if (unformat (input, "min-rx-fifo %U", unformat_memory_size,
-			 &memory_size))
-	{
-	  if (memory_size >= 0x100000000)
-	    {
-	      return clib_error_return
-		(0, "min-rx-fifo %llu (0x%llx) too large", memory_size,
-		 memory_size);
-	    }
-	  tcp_cfg.min_rx_fifo = memory_size;
-	}
-      else if (unformat (input, "mtu %u", &tcp_cfg.default_mtu))
-	;
-      else if (unformat (input, "rwnd-min-update-ack %d",
-			 &tcp_cfg.rwnd_min_update_ack))
-	;
-      else if (unformat (input, "initial-cwnd-multiplier %u",
-			 &cwnd_multiplier))
-	tcp_cfg.initial_cwnd_multiplier = cwnd_multiplier;
-      else if (unformat (input, "no-tx-pacing"))
-	tcp_cfg.enable_tx_pacing = 0;
-      else if (unformat (input, "tso"))
-	tcp_cfg.allow_tso = 1;
-      else if (unformat (input, "no-csum-offload"))
-	tcp_cfg.csum_offload = 0;
-      else if (unformat (input, "cc-algo %U", unformat_tcp_cc_algo,
-			 &tcp_cfg.cc_algo))
-	;
-      else if (unformat (input, "%U", unformat_tcp_cc_algo_cfg))
-	;
-      else if (unformat (input, "closewait-time %u", &tmp_time))
-	tcp_cfg.closewait_time = tmp_time / TCP_TIMER_TICK;
-      else if (unformat (input, "timewait-time %u", &tmp_time))
-	tcp_cfg.timewait_time = tmp_time / TCP_TIMER_TICK;
-      else if (unformat (input, "finwait1-time %u", &tmp_time))
-	tcp_cfg.finwait1_time = tmp_time / TCP_TIMER_TICK;
-      else if (unformat (input, "finwait2-time %u", &tmp_time))
-	tcp_cfg.finwait2_time = tmp_time / TCP_TIMER_TICK;
-      else if (unformat (input, "lastack-time %u", &tmp_time))
-	tcp_cfg.lastack_time = tmp_time / TCP_TIMER_TICK;
-      else if (unformat (input, "closing-time %u", &tmp_time))
-	tcp_cfg.closing_time = tmp_time / TCP_TIMER_TICK;
-      else if (unformat (input, "cleanup-time %u", &tmp_time))
-	tcp_cfg.cleanup_time = tmp_time / 1000.0;
-      else
-	return clib_error_return (0, "unknown input `%U'",
-				  format_unformat_error, input);
-    }
-  return 0;
-}
-
-VLIB_CONFIG_FUNCTION (tcp_config_fn, "tcp");
-
-
-/**
- * \brief Configure an ipv4 source address range
- * @param vm vlib_main_t pointer
- * @param start first ipv4 address in the source address range
- * @param end last ipv4 address in the source address range
- * @param table_id VRF / table ID, 0 for the default FIB
- * @return 0 if all OK, else an error indication from api_errno.h
- */
-
-int
-tcp_configure_v4_source_address_range (vlib_main_t * vm,
-				       ip4_address_t * start,
-				       ip4_address_t * end, u32 table_id)
-{
-  u32 start_host_byte_order, end_host_byte_order;
-  fib_prefix_t prefix;
-  fib_node_index_t fei;
-  u32 fib_index = 0;
-  u32 sw_if_index;
-  int rv;
-
-  clib_memset (&prefix, 0, sizeof (prefix));
-
-  fib_index = fib_table_find (FIB_PROTOCOL_IP4, table_id);
-
-  if (fib_index == ~0)
-    return VNET_API_ERROR_NO_SUCH_FIB;
-
-  start_host_byte_order = clib_net_to_host_u32 (start->as_u32);
-  end_host_byte_order = clib_net_to_host_u32 (end->as_u32);
-
-  /* sanity check for reversed args or some such */
-  if ((end_host_byte_order - start_host_byte_order) > (10 << 10))
-    return VNET_API_ERROR_INVALID_ARGUMENT;
-
-  /* Lookup the last address, to identify the interface involved */
-  prefix.fp_len = 32;
-  prefix.fp_proto = FIB_PROTOCOL_IP4;
-  memcpy (&prefix.fp_addr.ip4, end, sizeof (ip4_address_t));
-
-  fei = fib_table_lookup (fib_index, &prefix);
-
-  /* Couldn't find route to destination. Bail out. */
-  if (fei == FIB_NODE_INDEX_INVALID)
-    return VNET_API_ERROR_NEXT_HOP_NOT_IN_FIB;
-
-  sw_if_index = fib_entry_get_resolving_interface (fei);
-
-  /* Configure proxy arp across the range */
-  rv = ip4_neighbor_proxy_add (fib_index, start, end);
-
-  if (rv)
-    return rv;
-
-  rv = ip4_neighbor_proxy_enable (sw_if_index);
-
-  if (rv)
-    return rv;
-
-  do
-    {
-      dpo_id_t dpo = DPO_INVALID;
-
-      vec_add1 (tcp_cfg.ip4_src_addrs, start[0]);
-
-      /* Add local adjacencies for the range */
-
-      receive_dpo_add_or_lock (DPO_PROTO_IP4, ~0 /* sw_if_index */ ,
-			       NULL, &dpo);
-      prefix.fp_len = 32;
-      prefix.fp_proto = FIB_PROTOCOL_IP4;
-      prefix.fp_addr.ip4.as_u32 = start->as_u32;
-
-      fib_table_entry_special_dpo_update (fib_index,
-					  &prefix,
-					  FIB_SOURCE_API,
-					  FIB_ENTRY_FLAG_EXCLUSIVE, &dpo);
-      dpo_reset (&dpo);
-
-      start_host_byte_order++;
-      start->as_u32 = clib_host_to_net_u32 (start_host_byte_order);
-    }
-  while (start_host_byte_order <= end_host_byte_order);
-
-  return 0;
-}
-
-/**
- * \brief Configure an ipv6 source address range
- * @param vm vlib_main_t pointer
- * @param start first ipv6 address in the source address range
- * @param end last ipv6 address in the source address range
- * @param table_id VRF / table ID, 0 for the default FIB
- * @return 0 if all OK, else an error indication from api_errno.h
- */
-
-int
-tcp_configure_v6_source_address_range (vlib_main_t * vm,
-				       ip6_address_t * start,
-				       ip6_address_t * end, u32 table_id)
-{
-  fib_prefix_t prefix;
-  u32 fib_index = 0;
-  fib_node_index_t fei;
-  u32 sw_if_index;
-
-  clib_memset (&prefix, 0, sizeof (prefix));
-
-  fib_index = fib_table_find (FIB_PROTOCOL_IP6, table_id);
-
-  if (fib_index == ~0)
-    return VNET_API_ERROR_NO_SUCH_FIB;
-
-  while (1)
-    {
-      int i;
-      ip6_address_t tmp;
-      dpo_id_t dpo = DPO_INVALID;
-
-      /* Remember this address */
-      vec_add1 (tcp_cfg.ip6_src_addrs, start[0]);
-
-      /* Lookup the prefix, to identify the interface involved */
-      prefix.fp_len = 128;
-      prefix.fp_proto = FIB_PROTOCOL_IP6;
-      memcpy (&prefix.fp_addr.ip6, start, sizeof (ip6_address_t));
-
-      fei = fib_table_lookup (fib_index, &prefix);
-
-      /* Couldn't find route to destination. Bail out. */
-      if (fei == FIB_NODE_INDEX_INVALID)
-	return VNET_API_ERROR_NEXT_HOP_NOT_IN_FIB;
-
-      sw_if_index = fib_entry_get_resolving_interface (fei);
-
-      if (sw_if_index == (u32) ~ 0)
-	return VNET_API_ERROR_NO_MATCHING_INTERFACE;
-
-      /* Add a proxy neighbor discovery entry for this address */
-      ip6_neighbor_proxy_add (sw_if_index, start);
-
-      /* Add a receive adjacency for this address */
-      receive_dpo_add_or_lock (DPO_PROTO_IP6, ~0 /* sw_if_index */ ,
-			       NULL, &dpo);
-
-      fib_table_entry_special_dpo_update (fib_index,
-					  &prefix,
-					  FIB_SOURCE_API,
-					  FIB_ENTRY_FLAG_EXCLUSIVE, &dpo);
-      dpo_reset (&dpo);
-
-      /* Done with the entire range? */
-      if (!memcmp (start, end, sizeof (start[0])))
-	break;
-
-      /* Increment the address. DGMS. */
-      tmp = start[0];
-      for (i = 15; i >= 0; i--)
-	{
-	  tmp.as_u8[i] += 1;
-	  if (tmp.as_u8[i] != 0)
-	    break;
-	}
-      start[0] = tmp;
-    }
-  return 0;
-}
-
-static clib_error_t *
-tcp_src_address_fn (vlib_main_t * vm,
-		    unformat_input_t * input, vlib_cli_command_t * cmd_arg)
-{
-  ip4_address_t v4start, v4end;
-  ip6_address_t v6start, v6end;
-  u32 table_id = 0;
-  int v4set = 0;
-  int v6set = 0;
-  int rv;
-
-  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
-    {
-      if (unformat (input, "%U - %U", unformat_ip4_address, &v4start,
-		    unformat_ip4_address, &v4end))
-	v4set = 1;
-      else if (unformat (input, "%U", unformat_ip4_address, &v4start))
-	{
-	  memcpy (&v4end, &v4start, sizeof (v4start));
-	  v4set = 1;
-	}
-      else if (unformat (input, "%U - %U", unformat_ip6_address, &v6start,
-			 unformat_ip6_address, &v6end))
-	v6set = 1;
-      else if (unformat (input, "%U", unformat_ip6_address, &v6start))
-	{
-	  memcpy (&v6end, &v6start, sizeof (v6start));
-	  v6set = 1;
-	}
-      else if (unformat (input, "fib-table %d", &table_id))
-	;
-      else
-	break;
-    }
-
-  if (!v4set && !v6set)
-    return clib_error_return (0, "at least one v4 or v6 address required");
-
-  if (v4set)
-    {
-      rv = tcp_configure_v4_source_address_range (vm, &v4start, &v4end,
-						  table_id);
-      switch (rv)
-	{
-	case 0:
-	  break;
-
-	case VNET_API_ERROR_NO_SUCH_FIB:
-	  return clib_error_return (0, "Invalid table-id %d", table_id);
-
-	case VNET_API_ERROR_INVALID_ARGUMENT:
-	  return clib_error_return (0, "Invalid address range %U - %U",
-				    format_ip4_address, &v4start,
-				    format_ip4_address, &v4end);
-	default:
-	  return clib_error_return (0, "error %d", rv);
-	  break;
-	}
-    }
-  if (v6set)
-    {
-      rv = tcp_configure_v6_source_address_range (vm, &v6start, &v6end,
-						  table_id);
-      switch (rv)
-	{
-	case 0:
-	  break;
-
-	case VNET_API_ERROR_NO_SUCH_FIB:
-	  return clib_error_return (0, "Invalid table-id %d", table_id);
-
-	default:
-	  return clib_error_return (0, "error %d", rv);
-	  break;
-	}
-    }
-  return 0;
-}
-
-/* *INDENT-OFF* */
-VLIB_CLI_COMMAND (tcp_src_address_command, static) =
-{
-  .path = "tcp src-address",
-  .short_help = "tcp src-address <ip-addr> [- <ip-addr>] add src address range",
-  .function = tcp_src_address_fn,
-};
-/* *INDENT-ON* */
-
-static u8 *
-tcp_scoreboard_dump_trace (u8 * s, sack_scoreboard_t * sb)
-{
-#if TCP_SCOREBOARD_TRACE
-
-  scoreboard_trace_elt_t *block;
-  int i = 0;
-
-  if (!sb->trace)
-    return s;
-
-  s = format (s, "scoreboard trace:");
-  vec_foreach (block, sb->trace)
-  {
-    s = format (s, "{%u, %u, %u, %u, %u}, ", block->start, block->end,
-		block->ack, block->snd_una_max, block->group);
-    if ((++i % 3) == 0)
-      s = format (s, "\n");
-  }
-  return s;
-#else
-  return 0;
-#endif
-}
-
-static clib_error_t *
-tcp_show_scoreboard_trace_fn (vlib_main_t * vm, unformat_input_t * input,
-			      vlib_cli_command_t * cmd_arg)
-{
-  transport_connection_t *tconn = 0;
-  tcp_connection_t *tc;
-  u8 *s = 0;
-  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
-    {
-      if (unformat (input, "%U", unformat_transport_connection, &tconn,
-		    TRANSPORT_PROTO_TCP))
-	;
-      else
-	return clib_error_return (0, "unknown input `%U'",
-				  format_unformat_error, input);
-    }
-
-  if (!TCP_SCOREBOARD_TRACE)
-    {
-      vlib_cli_output (vm, "scoreboard tracing not enabled");
-      return 0;
-    }
-
-  tc = tcp_get_connection_from_transport (tconn);
-  s = tcp_scoreboard_dump_trace (s, &tc->sack_sb);
-  vlib_cli_output (vm, "%v", s);
-  return 0;
-}
-
-/* *INDENT-OFF* */
-VLIB_CLI_COMMAND (tcp_show_scoreboard_trace_command, static) =
-{
-  .path = "show tcp scoreboard trace",
-  .short_help = "show tcp scoreboard trace <connection>",
-  .function = tcp_show_scoreboard_trace_fn,
-};
-/* *INDENT-ON* */
-
-u8 *
-tcp_scoreboard_replay (u8 * s, tcp_connection_t * tc, u8 verbose)
-{
-  int i, trace_len;
-  scoreboard_trace_elt_t *trace;
-  u32 next_ack, left, group, has_new_ack = 0;
-  tcp_connection_t _dummy_tc, *dummy_tc = &_dummy_tc;
-  sack_block_t *block;
-
-  if (!TCP_SCOREBOARD_TRACE)
-    {
-      s = format (s, "scoreboard tracing not enabled");
-      return s;
-    }
-
-  if (!tc)
-    return s;
-
-  clib_memset (dummy_tc, 0, sizeof (*dummy_tc));
-  tcp_connection_timers_init (dummy_tc);
-  scoreboard_init (&dummy_tc->sack_sb);
-  dummy_tc->rcv_opts.flags |= TCP_OPTS_FLAG_SACK;
-
-#if TCP_SCOREBOARD_TRACE
-  trace = tc->sack_sb.trace;
-  trace_len = vec_len (tc->sack_sb.trace);
-#endif
-
-  for (i = 0; i < trace_len; i++)
-    {
-      if (trace[i].ack != 0)
-	{
-	  dummy_tc->snd_una = trace[i].ack - 1448;
-	  dummy_tc->snd_una_max = trace[i].ack;
-	}
-    }
-
-  left = 0;
-  while (left < trace_len)
-    {
-      group = trace[left].group;
-      vec_reset_length (dummy_tc->rcv_opts.sacks);
-      has_new_ack = 0;
-      while (trace[left].group == group)
-	{
-	  if (trace[left].ack != 0)
-	    {
-	      if (verbose)
-		s = format (s, "Adding ack %u, snd_una_max %u, segs: ",
-			    trace[left].ack, trace[left].snd_una_max);
-	      dummy_tc->snd_una_max = trace[left].snd_una_max;
-	      next_ack = trace[left].ack;
-	      has_new_ack = 1;
-	    }
-	  else
-	    {
-	      if (verbose)
-		s = format (s, "[%u, %u], ", trace[left].start,
-			    trace[left].end);
-	      vec_add2 (dummy_tc->rcv_opts.sacks, block, 1);
-	      block->start = trace[left].start;
-	      block->end = trace[left].end;
-	    }
-	  left++;
-	}
-
-      /* Push segments */
-      tcp_rcv_sacks (dummy_tc, next_ack);
-      if (has_new_ack)
-	dummy_tc->snd_una = next_ack;
-
-      if (verbose)
-	s = format (s, "result: %U", format_tcp_scoreboard,
-		    &dummy_tc->sack_sb);
-
-    }
-  s = format (s, "result: %U", format_tcp_scoreboard, &dummy_tc->sack_sb);
-
-  return s;
-}
-
-static clib_error_t *
-tcp_scoreboard_trace_fn (vlib_main_t * vm, unformat_input_t * input,
-			 vlib_cli_command_t * cmd_arg)
-{
-  transport_connection_t *tconn = 0;
-  tcp_connection_t *tc = 0;
-  u8 *str = 0;
-  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
-    {
-      if (unformat (input, "%U", unformat_transport_connection, &tconn,
-		    TRANSPORT_PROTO_TCP))
-	;
-      else
-	return clib_error_return (0, "unknown input `%U'",
-				  format_unformat_error, input);
-    }
-
-  if (!TCP_SCOREBOARD_TRACE)
-    {
-      vlib_cli_output (vm, "scoreboard tracing not enabled");
-      return 0;
-    }
-
-  tc = tcp_get_connection_from_transport (tconn);
-  if (!tc)
-    {
-      vlib_cli_output (vm, "connection not found");
-      return 0;
-    }
-  str = tcp_scoreboard_replay (str, tc, 1);
-  vlib_cli_output (vm, "%v", str);
-  return 0;
-}
-
-/* *INDENT-OFF* */
-VLIB_CLI_COMMAND (tcp_replay_scoreboard_command, static) =
-{
-  .path = "tcp replay scoreboard",
-  .short_help = "tcp replay scoreboard <connection>",
-  .function = tcp_scoreboard_trace_fn,
-};
-/* *INDENT-ON* */
-
-static clib_error_t *
-show_tcp_punt_fn (vlib_main_t * vm, unformat_input_t * input,
-		  vlib_cli_command_t * cmd_arg)
-{
-  tcp_main_t *tm = vnet_get_tcp_main ();
-  if (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
-    return clib_error_return (0, "unknown input `%U'", format_unformat_error,
-			      input);
-  vlib_cli_output (vm, "IPv4 TCP punt: %s",
-		   tm->punt_unknown4 ? "enabled" : "disabled");
-  vlib_cli_output (vm, "IPv6 TCP punt: %s",
-		   tm->punt_unknown6 ? "enabled" : "disabled");
-  return 0;
-}
-/* *INDENT-OFF* */
-VLIB_CLI_COMMAND (show_tcp_punt_command, static) =
-{
-  .path = "show tcp punt",
-  .short_help = "show tcp punt",
-  .function = show_tcp_punt_fn,
-};
-/* *INDENT-ON* */
-
-static clib_error_t *
-show_tcp_stats_fn (vlib_main_t * vm, unformat_input_t * input,
-		   vlib_cli_command_t * cmd)
-{
-  tcp_main_t *tm = vnet_get_tcp_main ();
-  tcp_worker_ctx_t *wrk;
-  u32 thread;
-
-  if (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
-    return clib_error_return (0, "unknown input `%U'", format_unformat_error,
-			      input);
-  for (thread = 0; thread < vec_len (tm->wrk_ctx); thread++)
-    {
-      wrk = tcp_get_worker (thread);
-      vlib_cli_output (vm, "Thread %u:\n", thread);
-
-      if (clib_fifo_elts (wrk->pending_timers))
-	vlib_cli_output (vm, " %lu pending timers",
-			 clib_fifo_elts (wrk->pending_timers));
-
-#define _(name,type,str)					\
-  if (wrk->stats.name)						\
-    vlib_cli_output (vm, " %lu %s", wrk->stats.name, str);
-      foreach_tcp_wrk_stat
-#undef _
-    }
-
-  return 0;
-}
-
-/* *INDENT-OFF* */
-VLIB_CLI_COMMAND (show_tcp_stats_command, static) =
-{
-  .path = "show tcp stats",
-  .short_help = "show tcp stats",
-  .function = show_tcp_stats_fn,
-};
-/* *INDENT-ON* */
-
-static clib_error_t *
-clear_tcp_stats_fn (vlib_main_t * vm, unformat_input_t * input,
-		    vlib_cli_command_t * cmd)
-{
-  tcp_main_t *tm = vnet_get_tcp_main ();
-  tcp_worker_ctx_t *wrk;
-  u32 thread;
-
-  if (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
-    return clib_error_return (0, "unknown input `%U'", format_unformat_error,
-			      input);
-
-  for (thread = 0; thread < vec_len (tm->wrk_ctx); thread++)
-    {
-      wrk = tcp_get_worker (thread);
-      clib_memset (&wrk->stats, 0, sizeof (wrk->stats));
-    }
-
-  return 0;
-}
-
-/* *INDENT-OFF* */
-VLIB_CLI_COMMAND (clear_tcp_stats_command, static) =
-{
-  .path = "clear tcp stats",
-  .short_help = "clear tcp stats",
-  .function = clear_tcp_stats_fn,
-};
-/* *INDENT-ON* */
-
 /*
  * fd.io coding-style-patch-verification: ON
  *
diff --git a/src/vnet/tcp/tcp.h b/src/vnet/tcp/tcp.h
index 30c95a48ffa..708d7566eb2 100644
--- a/src/vnet/tcp/tcp.h
+++ b/src/vnet/tcp/tcp.h
@@ -18,464 +18,13 @@
 
 #include <vnet/vnet.h>
 #include <vnet/ip/ip.h>
-#include <vnet/tcp/tcp_packet.h>
-#include <vnet/tcp/tcp_timer.h>
-#include <vnet/session/transport.h>
 #include <vnet/session/session.h>
+#include <vnet/tcp/tcp_types.h>
+#include <vnet/tcp/tcp_timer.h>
 #include <vnet/tcp/tcp_debug.h>
-
-#define TCP_TICK 0.001			/**< TCP tick period (s) */
-#define THZ (u32) (1/TCP_TICK)		/**< TCP tick frequency */
-#define TCP_TSTAMP_RESOLUTION TCP_TICK	/**< Time stamp resolution */
-#define TCP_PAWS_IDLE 24 * 24 * 60 * 60 * THZ /**< 24 days */
-#define TCP_FIB_RECHECK_PERIOD	1 * THZ	/**< Recheck every 1s */
-#define TCP_MAX_OPTION_SPACE 40
-#define TCP_CC_DATA_SZ 24
-#define TCP_MAX_GSO_SZ 65536
-#define TCP_RXT_MAX_BURST 10
-
-#define TCP_DUPACK_THRESHOLD 	3
-#define TCP_IW_N_SEGMENTS 	10
-#define TCP_ALWAYS_ACK		1	/**< On/off delayed acks */
-#define TCP_USE_SACKS		1	/**< Disable only for testing */
-
-/** TCP FSM state definitions as per RFC793. */
-#define foreach_tcp_fsm_state   \
-  _(CLOSED, "CLOSED")           \
-  _(LISTEN, "LISTEN")           \
-  _(SYN_SENT, "SYN_SENT")       \
-  _(SYN_RCVD, "SYN_RCVD")       \
-  _(ESTABLISHED, "ESTABLISHED") \
-  _(CLOSE_WAIT, "CLOSE_WAIT")   \
-  _(FIN_WAIT_1, "FIN_WAIT_1")   \
-  _(LAST_ACK, "LAST_ACK")       \
-  _(CLOSING, "CLOSING")         \
-  _(FIN_WAIT_2, "FIN_WAIT_2")   \
-  _(TIME_WAIT, "TIME_WAIT")
-
-typedef enum _tcp_state
-{
-#define _(sym, str) TCP_STATE_##sym,
-  foreach_tcp_fsm_state
-#undef _
-  TCP_N_STATES
-} tcp_state_t;
-
-format_function_t format_tcp_state;
-format_function_t format_tcp_flags;
-format_function_t format_tcp_sacks;
-format_function_t format_tcp_rcv_sacks;
-
-/** TCP timers */
-#define foreach_tcp_timer               \
-  _(RETRANSMIT, "RETRANSMIT")           \
-  _(DELACK, "DELAYED ACK")              \
-  _(PERSIST, "PERSIST")                 \
-  _(WAITCLOSE, "WAIT CLOSE")            \
-  _(RETRANSMIT_SYN, "RETRANSMIT SYN")   \
-
-typedef enum _tcp_timers
-{
-#define _(sym, str) TCP_TIMER_##sym,
-  foreach_tcp_timer
-#undef _
-  TCP_N_TIMERS
-} tcp_timers_e;
-
-#define TCP_TIMER_HANDLE_INVALID ((u32) ~0)
-
-#define TCP_TIMER_TICK		0.1		/**< Timer tick in seconds */
-#define TCP_TO_TIMER_TICK       TCP_TICK*10	/**< Factor for converting
-						     ticks to timer ticks */
-
-#define TCP_RTO_MAX 60 * THZ	/* Min max RTO (60s) as per RFC6298 */
-#define TCP_RTO_MIN 0.2 * THZ	/* Min RTO (200ms) - lower than standard */
-#define TCP_RTT_MAX 30 * THZ	/* 30s (probably too much) */
-#define TCP_RTO_SYN_RETRIES 3	/* SYN retries without doubling RTO */
-#define TCP_RTO_INIT 1 * THZ	/* Initial retransmit timer */
-#define TCP_RTO_BOFF_MAX 8	/* Max number of retries before reset */
-#define TCP_ESTABLISH_TIME (60 * THZ)	/* Connection establish timeout */
-
-/** Connection configuration flags */
-#define foreach_tcp_cfg_flag 			\
-  _(RATE_SAMPLE, "Rate sampling")		\
-  _(NO_CSUM_OFFLOAD, "No csum offload")    	\
-  _(NO_TSO, "TSO off")				\
-  _(TSO, "TSO")					\
-  _(NO_ENDPOINT,"No endpoint")			\
-
-typedef enum tcp_cfg_flag_bits_
-{
-#define _(sym, str) TCP_CFG_F_##sym##_BIT,
-  foreach_tcp_cfg_flag
-#undef _
-  TCP_CFG_N_FLAG_BITS
-} tcp_cfg_flag_bits_e;
-
-typedef enum tcp_cfg_flag_
-{
-#define _(sym, str) TCP_CFG_F_##sym = 1 << TCP_CFG_F_##sym##_BIT,
-  foreach_tcp_cfg_flag
-#undef _
-  TCP_CFG_N_FLAGS
-} tcp_cfg_flags_e;
-
-/** TCP connection flags */
-#define foreach_tcp_connection_flag             \
-  _(SNDACK, "Send ACK")                         \
-  _(FINSNT, "FIN sent")				\
-  _(RECOVERY, "Recovery")                    	\
-  _(FAST_RECOVERY, "Fast Recovery")		\
-  _(DCNT_PENDING, "Disconnect pending")		\
-  _(HALF_OPEN_DONE, "Half-open completed")	\
-  _(FINPNDG, "FIN pending")			\
-  _(RXT_PENDING, "Retransmit pending")		\
-  _(FRXT_FIRST, "Retransmit first")		\
-  _(DEQ_PENDING, "Dequeue pending ")		\
-  _(PSH_PENDING, "PSH pending")			\
-  _(FINRCVD, "FIN received")			\
-  _(ZERO_RWND_SENT, "Zero RWND sent")		\
-
-typedef enum tcp_connection_flag_bits_
-{
-#define _(sym, str) TCP_CONN_##sym##_BIT,
-  foreach_tcp_connection_flag
-#undef _
-  TCP_CONN_N_FLAG_BITS
-} tcp_connection_flag_bits_e;
-
-typedef enum tcp_connection_flag_
-{
-#define _(sym, str) TCP_CONN_##sym = 1 << TCP_CONN_##sym##_BIT,
-  foreach_tcp_connection_flag
-#undef _
-  TCP_CONN_N_FLAGS
-} tcp_connection_flags_e;
-
-#define TCP_SCOREBOARD_TRACE (0)
-#define TCP_MAX_SACK_BLOCKS 256	/**< Max number of SACK blocks stored */
-#define TCP_INVALID_SACK_HOLE_INDEX ((u32)~0)
-
-typedef struct _scoreboard_trace_elt
-{
-  u32 start;
-  u32 end;
-  u32 ack;
-  u32 snd_una_max;
-  u32 group;
-} scoreboard_trace_elt_t;
-
-typedef struct _sack_scoreboard_hole
-{
-  u32 next;		/**< Index for next entry in linked list */
-  u32 prev;		/**< Index for previous entry in linked list */
-  u32 start;		/**< Start sequence number */
-  u32 end;		/**< End sequence number */
-  u8 is_lost;		/**< Mark hole as lost */
-} sack_scoreboard_hole_t;
-
-typedef struct _sack_scoreboard
-{
-  sack_scoreboard_hole_t *holes;	/**< Pool of holes */
-  u32 head;				/**< Index of first entry */
-  u32 tail;				/**< Index of last entry */
-  u32 sacked_bytes;			/**< Number of bytes sacked in sb */
-  u32 last_sacked_bytes;		/**< Number of bytes last sacked */
-  u32 last_bytes_delivered;		/**< Sack bytes delivered to app */
-  u32 rxt_sacked;			/**< Rxt bytes last delivered */
-  u32 high_sacked;			/**< Highest byte sacked (fack) */
-  u32 high_rxt;				/**< Highest retransmitted sequence */
-  u32 rescue_rxt;			/**< Rescue sequence number */
-  u32 lost_bytes;			/**< Bytes lost as per RFC6675 */
-  u32 last_lost_bytes;			/**< Number of bytes last lost */
-  u32 cur_rxt_hole;			/**< Retransmitting from this hole */
-  u8 is_reneging;
-
-#if TCP_SCOREBOARD_TRACE
-  scoreboard_trace_elt_t *trace;
-#endif
-
-} sack_scoreboard_t;
-
-#if TCP_SCOREBOARD_TRACE
-#define tcp_scoreboard_trace_add(_tc, _ack) 				\
-{									\
-    static u64 _group = 0;						\
-    sack_scoreboard_t *_sb = &_tc->sack_sb;				\
-    sack_block_t *_sack, *_sacks;					\
-    scoreboard_trace_elt_t *_elt;					\
-    int i;								\
-    _group++;								\
-    _sacks = _tc->rcv_opts.sacks;					\
-    for (i = 0; i < vec_len (_sacks); i++) 				\
-      {									\
-	_sack = &_sacks[i];						\
-	vec_add2 (_sb->trace, _elt, 1);					\
-	_elt->start = _sack->start;					\
-	_elt->end = _sack->end;						\
-	_elt->ack = _elt->end == _ack ? _ack : 0;			\
-	_elt->snd_una_max = _elt->end == _ack ? _tc->snd_una_max : 0;	\
-	_elt->group = _group;						\
-      }									\
-}
-#else
-#define tcp_scoreboard_trace_add(_tc, _ack)
-#endif
-
-sack_scoreboard_hole_t *scoreboard_next_rxt_hole (sack_scoreboard_t * sb,
-						  sack_scoreboard_hole_t *
-						  start, u8 have_sent_1_smss,
-						  u8 * can_rescue,
-						  u8 * snd_limited);
-sack_scoreboard_hole_t *scoreboard_get_hole (sack_scoreboard_t * sb,
-					     u32 index);
-
-sack_scoreboard_hole_t *scoreboard_next_hole (sack_scoreboard_t * sb,
-					      sack_scoreboard_hole_t * hole);
-sack_scoreboard_hole_t *scoreboard_prev_hole (sack_scoreboard_t * sb,
-					      sack_scoreboard_hole_t * hole);
-sack_scoreboard_hole_t *scoreboard_first_hole (sack_scoreboard_t * sb);
-sack_scoreboard_hole_t *scoreboard_last_hole (sack_scoreboard_t * sb);
-
-void scoreboard_clear (sack_scoreboard_t * sb);
-void scoreboard_clear_reneging (sack_scoreboard_t * sb, u32 start, u32 end);
-void scoreboard_init (sack_scoreboard_t * sb);
-void scoreboard_init_rxt (sack_scoreboard_t * sb, u32 snd_una);
-u8 *format_tcp_scoreboard (u8 * s, va_list * args);
-
-#define TCP_BTS_INVALID_INDEX	((u32)~0)
-
-typedef enum tcp_bts_flags_
-{
-  TCP_BTS_IS_RXT = 1,
-  TCP_BTS_IS_APP_LIMITED = 1 << 1,
-  TCP_BTS_IS_SACKED = 1 << 2,
-  TCP_BTS_IS_RXT_LOST = 1 << 3,
-} __clib_packed tcp_bts_flags_t;
-
-typedef struct tcp_bt_sample_
-{
-  u32 next;			/**< Next sample index in list */
-  u32 prev;			/**< Previous sample index in list */
-  u32 min_seq;			/**< Min seq number in sample */
-  u32 max_seq;			/**< Max seq number. Set for rxt samples */
-  u64 delivered;		/**< Total delivered bytes for sample */
-  f64 delivered_time;		/**< Delivered time when sample taken */
-  f64 tx_time;			/**< Transmit time for the burst */
-  f64 first_tx_time;		/**< Connection first tx time at tx */
-  u64 tx_in_flight;		/**< In flight at tx time */
-  u64 tx_lost;			/**< Lost at tx time */
-  tcp_bts_flags_t flags;	/**< Sample flag */
-} tcp_bt_sample_t;
-
-typedef struct tcp_rate_sample_
-{
-  u64 prior_delivered;		/**< Delivered of sample used for rate, i.e.,
-				     total bytes delivered at prior_time */
-  f64 prior_time;		/**< Delivered time of sample used for rate */
-  f64 interval_time;		/**< Time to ack the bytes delivered */
-  f64 rtt_time;			/**< RTT for sample */
-  u64 tx_in_flight;		/**< In flight at (re)transmit time */
-  u64 tx_lost;			/**< Lost over interval */
-  u32 delivered;		/**< Bytes delivered in interval_time */
-  u32 acked_and_sacked;		/**< Bytes acked + sacked now */
-  u32 last_lost;		/**< Bytes lost now */
-  u32 lost;			/**< Number of bytes lost over interval */
-  tcp_bts_flags_t flags;	/**< Rate sample flags from bt sample */
-} tcp_rate_sample_t;
-
-typedef struct tcp_byte_tracker_
-{
-  tcp_bt_sample_t *samples;	/**< Pool of samples */
-  rb_tree_t sample_lookup;	/**< Rbtree for sample lookup by min_seq */
-  u32 head;			/**< Head of samples linked list */
-  u32 tail;			/**< Tail of samples linked list */
-  u32 last_ooo;			/**< Cached last ooo sample */
-} tcp_byte_tracker_t;
-
-typedef enum _tcp_cc_algorithm_type
-{
-  TCP_CC_NEWRENO,
-  TCP_CC_CUBIC,
-  TCP_CC_LAST = TCP_CC_CUBIC
-} tcp_cc_algorithm_type_e;
-
-typedef struct _tcp_cc_algorithm tcp_cc_algorithm_t;
-
-typedef enum _tcp_cc_ack_t
-{
-  TCP_CC_ACK,
-  TCP_CC_DUPACK,
-  TCP_CC_PARTIALACK
-} tcp_cc_ack_t;
-
-typedef enum tcp_cc_event_
-{
-  TCP_CC_EVT_START_TX,
-} tcp_cc_event_t;
-
-/*
- * As per RFC4898 tcpEStatsStackSoftErrors
- */
-typedef struct tcp_errors_
-{
-  u32 below_data_wnd;	/**< All data in seg is below snd_una */
-  u32 above_data_wnd;	/**< Some data in segment is above snd_wnd */
-  u32 below_ack_wnd;	/**< Acks for data below snd_una */
-  u32 above_ack_wnd;	/**< Acks for data not sent */
-} tcp_errors_t;
-
-typedef struct _tcp_connection
-{
-  CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);
-  transport_connection_t connection;  /**< Common transport data. First! */
-
-  u8 state;			/**< TCP state as per tcp_state_t */
-  u8 cfg_flags;			/**< Connection configuration flags */
-  u16 flags;			/**< Connection flags (see tcp_conn_flags_e) */
-  u32 timers[TCP_N_TIMERS];	/**< Timer handles into timer wheel */
-
-  u64 segs_in;		/** RFC4022/4898 tcpHCInSegs/tcpEStatsPerfSegsIn */
-  u64 bytes_in;		/** RFC4898 tcpEStatsPerfHCDataOctetsIn */
-  u64 segs_out;		/** RFC4898 tcpEStatsPerfSegsOut */
-  u64 bytes_out;	/** RFC4898 tcpEStatsPerfHCDataOctetsOut */
-
-  /** Send sequence variables RFC793 */
-  u32 snd_una;		/**< oldest unacknowledged sequence number */
-  u32 snd_una_max;	/**< newest unacknowledged sequence number + 1*/
-  u32 snd_wnd;		/**< send window */
-  u32 snd_wl1;		/**< seq number used for last snd.wnd update */
-  u32 snd_wl2;		/**< ack number used for last snd.wnd update */
-  u32 snd_nxt;		/**< next seq number to be sent */
-  u16 snd_mss;		/**< Effective send max seg (data) size */
-
-  u64 data_segs_in;	/** RFC4898 tcpEStatsPerfDataSegsIn */
-  u64 data_segs_out;	/** RFC4898 tcpEStatsPerfDataSegsOut */
-
-  /** Receive sequence variables RFC793 */
-  u32 rcv_nxt;		/**< next sequence number expected */
-  u32 rcv_wnd;		/**< receive window we expect */
-
-  u32 rcv_las;		/**< rcv_nxt at last ack sent/rcv_wnd update */
-  u32 iss;		/**< initial sent sequence */
-  u32 irs;		/**< initial remote sequence */
-
-  /* Options */
-  u8 snd_opts_len;		/**< Tx options len */
-  u8 rcv_wscale;		/**< Window scale to advertise to peer */
-  u8 snd_wscale;		/**< Window scale to use when sending */
-  u32 tsval_recent;		/**< Last timestamp received */
-  u32 tsval_recent_age;		/**< When last updated tstamp_recent*/
-  tcp_options_t snd_opts;	/**< Tx options for connection */
-  tcp_options_t rcv_opts;	/**< Rx options for connection */
-
-  sack_block_t *snd_sacks;	/**< Vector of SACKs to send. XXX Fixed size? */
-  u8 snd_sack_pos;		/**< Position in vec of first block to send */
-  sack_block_t *snd_sacks_fl;	/**< Vector for building new list */
-  sack_scoreboard_t sack_sb;	/**< SACK "scoreboard" that tracks holes */
-
-  u16 rcv_dupacks;	/**< Number of recent DUPACKs received */
-  u32 dupacks_in;	/**< RFC4898 tcpEStatsStackDupAcksIn*/
-  u8 pending_dupacks;	/**< Number of DUPACKs to be sent */
-  u32 dupacks_out;	/**< RFC4898 tcpEStatsPathDupAcksOut */
-
-  /* Congestion control */
-  u32 cwnd;		/**< Congestion window */
-  u32 cwnd_acc_bytes;	/**< Bytes accumulated for cwnd increment */
-  u32 ssthresh;		/**< Slow-start threshold */
-  u32 prev_ssthresh;	/**< ssthresh before congestion */
-  u32 prev_cwnd;	/**< ssthresh before congestion */
-  u32 bytes_acked;	/**< Bytes acknowledged by current segment */
-  u32 burst_acked;	/**< Bytes acknowledged in current burst */
-  u32 snd_rxt_bytes;	/**< Retransmitted bytes during current cc event */
-  u32 snd_rxt_ts;	/**< Timestamp when first packet is retransmitted */
-  u32 prr_delivered;	/**< RFC6937 bytes delivered during current event */
-  u32 prr_start;	/**< snd_una when prr starts */
-  u32 rxt_delivered;	/**< Rxt bytes delivered during current cc event */
-  u32 rxt_head;		/**< snd_una last time we re rxted the head */
-  u32 tsecr_last_ack;	/**< Timestamp echoed to us in last healthy ACK */
-  u32 snd_congestion;	/**< snd_una_max when congestion is detected */
-  u32 tx_fifo_size;	/**< Tx fifo size. Used to constrain cwnd */
-  tcp_cc_algorithm_t *cc_algo;	/**< Congestion control algorithm */
-  u8 cc_data[TCP_CC_DATA_SZ];	/**< Congestion control algo private data */
-
-  u32 fr_occurences;	/**< fast-retransmit occurrences RFC4898
-			     tcpEStatsStackFastRetran */
-  u32 tr_occurences;	/**< timer-retransmit occurrences */
-  u64 bytes_retrans;	/**< RFC4898 tcpEStatsPerfOctetsRetrans */
-  u64 segs_retrans;	/**< RFC4898 tcpEStatsPerfSegsRetrans*/
-
-  /* RTT and RTO */
-  u32 rto;		/**< Retransmission timeout */
-  u32 rto_boff;		/**< Index for RTO backoff */
-  u32 srtt;		/**< Smoothed RTT */
-  u32 rttvar;		/**< Smoothed mean RTT difference. Approximates variance */
-  u32 rtt_seq;		/**< Sequence number for tracked ACK */
-  f64 rtt_ts;		/**< Timestamp for tracked ACK */
-  f64 mrtt_us;		/**< High precision mrtt from tracked acks */
-
-  u32 psh_seq;		/**< Add psh header for seg that includes this */
-  u32 next_node_index;	/**< Can be used to control next node in output */
-  u32 next_node_opaque;	/**< Opaque to pass to next node */
-  u32 limited_transmit;	/**< snd_nxt when limited transmit starts */
-  u32 sw_if_index;	/**< Interface for the connection */
-
-  /* Delivery rate estimation */
-  u64 delivered;		/**< Total bytes delivered to peer */
-  u64 app_limited;		/**< Delivered when app-limited detected */
-  f64 delivered_time;		/**< Time last bytes were acked */
-  f64 first_tx_time;		/**< Send time for recently delivered/sent */
-  u64 lost;			/**< Total bytes lost */
-  tcp_byte_tracker_t *bt;	/**< Tx byte tracker */
-
-  tcp_errors_t errors;	/**< Soft connection errors */
-
-  f64 start_ts;		/**< Timestamp when connection initialized */
-  u32 last_fib_check;	/**< Last time we checked fib route for peer */
-  u16 mss;		/**< Our max seg size that includes options */
-  u32 timestamp_delta;	/**< Offset for timestamp */
-  u32 ipv6_flow_label;	/**< flow label for ipv6 header */
-
-#define rst_state snd_wl1
-} tcp_connection_t;
-
-/* *INDENT-OFF* */
-struct _tcp_cc_algorithm
-{
-  const char *name;
-  uword (*unformat_cfg) (unformat_input_t * input);
-  void (*init) (tcp_connection_t * tc);
-  void (*cleanup) (tcp_connection_t * tc);
-  void (*rcv_ack) (tcp_connection_t * tc, tcp_rate_sample_t *rs);
-  void (*rcv_cong_ack) (tcp_connection_t * tc, tcp_cc_ack_t ack,
-			tcp_rate_sample_t *rs);
-  void (*congestion) (tcp_connection_t * tc);
-  void (*loss) (tcp_connection_t * tc);
-  void (*recovered) (tcp_connection_t * tc);
-  void (*undo_recovery) (tcp_connection_t * tc);
-  void (*event) (tcp_connection_t *tc, tcp_cc_event_t evt);
-  u64 (*get_pacing_rate) (tcp_connection_t *tc);
-};
-/* *INDENT-ON* */
-
-#define tcp_fastrecovery_on(tc) (tc)->flags |= TCP_CONN_FAST_RECOVERY
-#define tcp_fastrecovery_off(tc) (tc)->flags &= ~TCP_CONN_FAST_RECOVERY
-#define tcp_recovery_on(tc) (tc)->flags |= TCP_CONN_RECOVERY
-#define tcp_recovery_off(tc) (tc)->flags &= ~TCP_CONN_RECOVERY
-#define tcp_in_fastrecovery(tc) ((tc)->flags & TCP_CONN_FAST_RECOVERY)
-#define tcp_in_recovery(tc) ((tc)->flags & (TCP_CONN_RECOVERY))
-#define tcp_in_slowstart(tc) (tc->cwnd < tc->ssthresh)
-#define tcp_disconnect_pending(tc) ((tc)->flags & TCP_CONN_DCNT_PENDING)
-#define tcp_disconnect_pending_on(tc) ((tc)->flags |= TCP_CONN_DCNT_PENDING)
-#define tcp_disconnect_pending_off(tc) ((tc)->flags &= ~TCP_CONN_DCNT_PENDING)
-#define tcp_fastrecovery_first(tc) ((tc)->flags & TCP_CONN_FRXT_FIRST)
-#define tcp_fastrecovery_first_on(tc) ((tc)->flags |= TCP_CONN_FRXT_FIRST)
-#define tcp_fastrecovery_first_off(tc) ((tc)->flags &= ~TCP_CONN_FRXT_FIRST)
-
-#define tcp_in_cong_recovery(tc) ((tc)->flags & 		\
-	  (TCP_CONN_FAST_RECOVERY | TCP_CONN_RECOVERY))
-
-#define tcp_csum_offload(tc) (!((tc)->cfg_flags & TCP_CFG_F_NO_CSUM_OFFLOAD))
+#include <vnet/tcp/tcp_sack.h>
+#include <vnet/tcp/tcp_bt.h>
+#include <vnet/tcp/tcp_cc.h>
 
 typedef void (timer_expiration_handler) (tcp_connection_t * tc);
 
@@ -484,17 +33,6 @@ extern timer_expiration_handler tcp_timer_retransmit_handler;
 extern timer_expiration_handler tcp_timer_persist_handler;
 extern timer_expiration_handler tcp_timer_retransmit_syn_handler;
 
-always_inline void
-tcp_cong_recovery_off (tcp_connection_t * tc)
-{
-  tc->flags &= ~(TCP_CONN_FAST_RECOVERY | TCP_CONN_RECOVERY);
-  tcp_fastrecovery_first_off (tc);
-}
-
-#define tcp_zero_rwnd_sent(tc) ((tc)->flags & TCP_CONN_ZERO_RWND_SENT)
-#define tcp_zero_rwnd_sent_on(tc) (tc)->flags |= TCP_CONN_ZERO_RWND_SENT
-#define tcp_zero_rwnd_sent_off(tc) (tc)->flags &= ~TCP_CONN_ZERO_RWND_SENT
-
 typedef enum _tcp_error
 {
 #define tcp_error(n,s) TCP_ERROR_##n,
@@ -752,14 +290,6 @@ tcp_get_worker (u32 thread_index)
   return &tcp_main.wrk_ctx[thread_index];
 }
 
-always_inline tcp_header_t *
-tcp_buffer_hdr (vlib_buffer_t * b)
-{
-  ASSERT ((signed) b->current_data >= (signed) -VLIB_BUFFER_PRE_DATA_SIZE);
-  return (tcp_header_t *) (b->data + b->current_data
-			   + vnet_buffer (b)->tcp.hdr_offset);
-}
-
 #if (VLIB_BUFFER_TRACE_TRAJECTORY)
 #define tcp_trajectory_add_start(b, start)			\
 {								\
@@ -769,84 +299,15 @@ tcp_buffer_hdr (vlib_buffer_t * b)
 #define tcp_trajectory_add_start(b, start)
 #endif
 
-clib_error_t *vnet_tcp_enable_disable (vlib_main_t * vm, u8 is_en);
-
-void tcp_punt_unknown (vlib_main_t * vm, u8 is_ip4, u8 is_add);
-
-always_inline tcp_connection_t *
-tcp_connection_get (u32 conn_index, u32 thread_index)
-{
-  tcp_worker_ctx_t *wrk = tcp_get_worker (thread_index);
-  if (PREDICT_FALSE (pool_is_free_index (wrk->connections, conn_index)))
-    return 0;
-  return pool_elt_at_index (wrk->connections, conn_index);
-}
-
-always_inline tcp_connection_t *
-tcp_connection_get_if_valid (u32 conn_index, u32 thread_index)
-{
-  tcp_worker_ctx_t *wrk;
-  if (thread_index >= vec_len (tcp_main.wrk_ctx))
-    return 0;
-  wrk = tcp_get_worker (thread_index);
-  if (pool_is_free_index (wrk->connections, conn_index))
-    return 0;
-  return pool_elt_at_index (wrk->connections, conn_index);
-}
-
-always_inline tcp_connection_t *
-tcp_get_connection_from_transport (transport_connection_t * tconn)
-{
-  return (tcp_connection_t *) tconn;
-}
-
-always_inline void
-tcp_connection_set_state (tcp_connection_t * tc, tcp_state_t state)
-{
-  tc->state = state;
-  TCP_EVT (TCP_EVT_STATE_CHANGE, tc);
-}
-
-void tcp_connection_close (tcp_connection_t * tc);
-void tcp_connection_cleanup (tcp_connection_t * tc);
-void tcp_connection_del (tcp_connection_t * tc);
-int tcp_half_open_connection_cleanup (tcp_connection_t * tc);
 tcp_connection_t *tcp_connection_alloc (u8 thread_index);
 tcp_connection_t *tcp_connection_alloc_w_base (u8 thread_index,
 					       tcp_connection_t * base);
 void tcp_connection_free (tcp_connection_t * tc);
-int tcp_configure_v4_source_address_range (vlib_main_t * vm,
-					   ip4_address_t * start,
-					   ip4_address_t * end, u32 table_id);
-int tcp_configure_v6_source_address_range (vlib_main_t * vm,
-					   ip6_address_t * start,
-					   ip6_address_t * end, u32 table_id);
-void tcp_api_reference (void);
-u8 *format_tcp_connection (u8 * s, va_list * args);
-u8 *format_tcp_connection_id (u8 * s, va_list * args);
-
-always_inline tcp_connection_t *
-tcp_listener_get (u32 tli)
-{
-  tcp_connection_t *tc = 0;
-  if (!pool_is_free_index (tcp_main.listener_pool, tli))
-    tc = pool_elt_at_index (tcp_main.listener_pool, tli);
-  return tc;
-}
-
-always_inline tcp_connection_t *
-tcp_half_open_connection_get (u32 conn_index)
-{
-  tcp_connection_t *tc = 0;
-  clib_spinlock_lock_if_init (&tcp_main.half_open_lock);
-  if (!pool_is_free_index (tcp_main.half_open_connections, conn_index))
-    tc = pool_elt_at_index (tcp_main.half_open_connections, conn_index);
-  clib_spinlock_unlock_if_init (&tcp_main.half_open_lock);
-  return tc;
-}
+void tcp_connection_close (tcp_connection_t * tc);
+void tcp_connection_cleanup (tcp_connection_t * tc);
+void tcp_connection_del (tcp_connection_t * tc);
+int tcp_half_open_connection_cleanup (tcp_connection_t * tc);
 
-void tcp_make_fin (tcp_connection_t * tc, vlib_buffer_t * b);
-void tcp_make_synack (tcp_connection_t * ts, vlib_buffer_t * b);
 void tcp_send_reset_w_pkt (tcp_connection_t * tc, vlib_buffer_t * pkt,
 			   u32 thread_index, u8 is_ip4);
 void tcp_send_reset (tcp_connection_t * tc);
@@ -854,256 +315,17 @@ void tcp_send_syn (tcp_connection_t * tc);
 void tcp_send_synack (tcp_connection_t * tc);
 void tcp_send_fin (tcp_connection_t * tc);
 void tcp_send_ack (tcp_connection_t * tc);
-void tcp_update_burst_snd_vars (tcp_connection_t * tc);
-void tcp_update_rto (tcp_connection_t * tc);
 void tcp_send_window_update_ack (tcp_connection_t * tc);
 
 void tcp_program_ack (tcp_connection_t * tc);
 void tcp_program_dupack (tcp_connection_t * tc);
 void tcp_program_retransmit (tcp_connection_t * tc);
 
-/*
- * Rate estimation
- */
-
-/**
- * Byte tracker initialize
- *
- * @param tc	connection for which the byte tracker should be allocated and
- * 		initialized
- */
-void tcp_bt_init (tcp_connection_t * tc);
-/**
- * Byte tracker cleanup
- *
- * @param tc	connection for which the byte tracker should be cleaned up
- */
-void tcp_bt_cleanup (tcp_connection_t * tc);
-/**
- * Flush byte tracker samples
- *
- * @param tc	tcp connection for which samples should be flushed
- */
-void tcp_bt_flush_samples (tcp_connection_t * tc);
-/**
- * Track a tcp tx burst
- *
- * @param tc	tcp connection
- */
-void tcp_bt_track_tx (tcp_connection_t * tc, u32 len);
-/**
- * Track a tcp retransmission
- *
- * @param tc	tcp connection
- * @param start	start sequence number
- * @param end	end sequence number
- */
-void tcp_bt_track_rxt (tcp_connection_t * tc, u32 start, u32 end);
-/**
- * Generate a delivery rate sample from recently acked bytes
- *
- * @param tc	tcp connection
- * @param rs	resulting rate sample
- */
-void tcp_bt_sample_delivery_rate (tcp_connection_t * tc,
-				  tcp_rate_sample_t * rs);
-/**
- * Check if sample to be generated is app limited
- *
- * @param tc	tcp connection
- */
-void tcp_bt_check_app_limited (tcp_connection_t * tc);
-/**
- * Check if the byte tracker is in sane state
- *
- * Should be used only for testing
- *
- * @param bt	byte tracker
- */
-int tcp_bt_is_sane (tcp_byte_tracker_t * bt);
-u8 *format_tcp_bt (u8 * s, va_list * args);
-
-always_inline u32
-tcp_end_seq (tcp_header_t * th, u32 len)
-{
-  return th->seq_number + tcp_is_syn (th) + tcp_is_fin (th) + len;
-}
-
-/* Modulo arithmetic for TCP sequence numbers */
-#define seq_lt(_s1, _s2) ((i32)((_s1)-(_s2)) < 0)
-#define seq_leq(_s1, _s2) ((i32)((_s1)-(_s2)) <= 0)
-#define seq_gt(_s1, _s2) ((i32)((_s1)-(_s2)) > 0)
-#define seq_geq(_s1, _s2) ((i32)((_s1)-(_s2)) >= 0)
-#define seq_max(_s1, _s2) (seq_gt((_s1), (_s2)) ? (_s1) : (_s2))
-
-/* Modulo arithmetic for timestamps */
-#define timestamp_lt(_t1, _t2) ((i32)((_t1)-(_t2)) < 0)
-#define timestamp_leq(_t1, _t2) ((i32)((_t1)-(_t2)) <= 0)
-
-/**
- * Our estimate of the number of bytes that have left the network
- */
-always_inline u32
-tcp_bytes_out (const tcp_connection_t * tc)
-{
-  if (tcp_opts_sack_permitted (&tc->rcv_opts))
-    return tc->sack_sb.sacked_bytes + tc->sack_sb.lost_bytes;
-  else
-    return clib_min (tc->rcv_dupacks * tc->snd_mss,
-		     tc->snd_nxt - tc->snd_una);
-}
-
-/**
- * Our estimate of the number of bytes in flight (pipe size)
- */
-always_inline u32
-tcp_flight_size (const tcp_connection_t * tc)
-{
-  int flight_size;
-
-  flight_size = (int) (tc->snd_nxt - tc->snd_una) - tcp_bytes_out (tc)
-    + tc->snd_rxt_bytes - tc->rxt_delivered;
-
-  ASSERT (flight_size >= 0);
-
-  return flight_size;
-}
-
-/**
- * Initial cwnd as per RFC5681
- */
-always_inline u32
-tcp_initial_cwnd (const tcp_connection_t * tc)
-{
-  if (tcp_cfg.initial_cwnd_multiplier > 0)
-    return tcp_cfg.initial_cwnd_multiplier * tc->snd_mss;
-
-  if (tc->snd_mss > 2190)
-    return 2 * tc->snd_mss;
-  else if (tc->snd_mss > 1095)
-    return 3 * tc->snd_mss;
-  else
-    return 4 * tc->snd_mss;
-}
-
-/*
- * Accumulate acked bytes for cwnd increase
- *
- * Once threshold bytes are accumulated, snd_mss bytes are added
- * to the cwnd.
- */
-always_inline void
-tcp_cwnd_accumulate (tcp_connection_t * tc, u32 thresh, u32 bytes)
-{
-  tc->cwnd_acc_bytes += bytes;
-  if (tc->cwnd_acc_bytes >= thresh)
-    {
-      u32 inc = tc->cwnd_acc_bytes / thresh;
-      tc->cwnd_acc_bytes -= inc * thresh;
-      tc->cwnd += inc * tc->snd_mss;
-      tc->cwnd = clib_min (tc->cwnd, tc->tx_fifo_size);
-    }
-}
-
-always_inline u32
-tcp_loss_wnd (const tcp_connection_t * tc)
-{
-  /* Whatever we have in flight + the packet we're about to send */
-  return tcp_flight_size (tc) + tc->snd_mss;
-}
-
-always_inline u32
-tcp_available_snd_wnd (const tcp_connection_t * tc)
-{
-  return clib_min (tc->cwnd, tc->snd_wnd);
-}
-
-always_inline u32
-tcp_available_output_snd_space (const tcp_connection_t * tc)
-{
-  u32 available_wnd = tcp_available_snd_wnd (tc);
-  int flight_size = (int) (tc->snd_nxt - tc->snd_una);
-
-  if (available_wnd <= flight_size)
-    return 0;
-
-  return available_wnd - flight_size;
-}
-
-/**
- * Estimate of how many bytes we can still push into the network
- */
-always_inline u32
-tcp_available_cc_snd_space (const tcp_connection_t * tc)
-{
-  u32 available_wnd = tcp_available_snd_wnd (tc);
-  u32 flight_size = tcp_flight_size (tc);
-
-  if (available_wnd <= flight_size)
-    return 0;
-
-  return available_wnd - flight_size;
-}
-
-static inline u8
-tcp_is_descheduled (tcp_connection_t * tc)
-{
-  return (transport_connection_is_descheduled (&tc->connection) ? 1 : 0);
-}
-
-always_inline u8
-tcp_is_lost_fin (tcp_connection_t * tc)
-{
-  if ((tc->flags & TCP_CONN_FINSNT) && (tc->snd_una_max - tc->snd_una == 1))
-    return 1;
-  return 0;
-}
-
+void tcp_update_burst_snd_vars (tcp_connection_t * tc);
 u32 tcp_snd_space (tcp_connection_t * tc);
 int tcp_fastrecovery_prr_snd_space (tcp_connection_t * tc);
 void tcp_reschedule (tcp_connection_t * tc);
-
 fib_node_index_t tcp_lookup_rmt_in_fib (tcp_connection_t * tc);
-
-/* Made public for unit testing only */
-void tcp_update_sack_list (tcp_connection_t * tc, u32 start, u32 end);
-u32 tcp_sack_list_bytes (tcp_connection_t * tc);
-
-always_inline u32
-tcp_time_now (void)
-{
-  return tcp_main.wrk_ctx[vlib_get_thread_index ()].time_now;
-}
-
-always_inline u32
-tcp_time_now_w_thread (u32 thread_index)
-{
-  return tcp_main.wrk_ctx[thread_index].time_now;
-}
-
-/**
- * Generate timestamp for tcp connection
- */
-always_inline u32
-tcp_tstamp (tcp_connection_t * tc)
-{
-  return (tcp_main.wrk_ctx[tc->c_thread_index].time_now -
-	  tc->timestamp_delta);
-}
-
-always_inline f64
-tcp_time_now_us (u32 thread_index)
-{
-  return transport_time_now (thread_index);
-}
-
-always_inline u32
-tcp_set_time_now (tcp_worker_ctx_t * wrk)
-{
-  wrk->time_now = clib_cpu_time_now () * tcp_main.tstamp_ticks_per_clock;
-  return wrk->time_now;
-}
-
 u32 tcp_session_push_header (transport_connection_t * tconn,
 			     vlib_buffer_t * b);
 int tcp_session_custom_tx (void *conn, u32 max_burst_size);
@@ -1117,64 +339,22 @@ void tcp_connection_tx_pacer_reset (tcp_connection_t * tc, u32 window,
 				    u32 start_bucket);
 void tcp_program_cleanup (tcp_worker_ctx_t * wrk, tcp_connection_t * tc);
 
-always_inline void
-tcp_cc_rcv_ack (tcp_connection_t * tc, tcp_rate_sample_t * rs)
-{
-  tc->cc_algo->rcv_ack (tc, rs);
-  tc->tsecr_last_ack = tc->rcv_opts.tsecr;
-}
-
-static inline void
-tcp_cc_rcv_cong_ack (tcp_connection_t * tc, tcp_cc_ack_t ack_type,
-		     tcp_rate_sample_t * rs)
-{
-  tc->cc_algo->rcv_cong_ack (tc, ack_type, rs);
-}
-
-static inline void
-tcp_cc_congestion (tcp_connection_t * tc)
-{
-  tc->cc_algo->congestion (tc);
-}
-
-static inline void
-tcp_cc_loss (tcp_connection_t * tc)
-{
-  tc->cc_algo->loss (tc);
-}
-
-static inline void
-tcp_cc_recovered (tcp_connection_t * tc)
-{
-  tc->cc_algo->recovered (tc);
-}
-
-static inline void
-tcp_cc_undo_recovery (tcp_connection_t * tc)
-{
-  if (tc->cc_algo->undo_recovery)
-    tc->cc_algo->undo_recovery (tc);
-}
-
-static inline void
-tcp_cc_event (tcp_connection_t * tc, tcp_cc_event_t evt)
-{
-  if (tc->cc_algo->event)
-    tc->cc_algo->event (tc, evt);
-}
-
-static inline u64
-tcp_cc_get_pacing_rate (tcp_connection_t * tc)
-{
-  if (tc->cc_algo->get_pacing_rate)
-    return tc->cc_algo->get_pacing_rate (tc);
+void tcp_punt_unknown (vlib_main_t * vm, u8 is_ip4, u8 is_add);
+int tcp_configure_v4_source_address_range (vlib_main_t * vm,
+					   ip4_address_t * start,
+					   ip4_address_t * end, u32 table_id);
+int tcp_configure_v6_source_address_range (vlib_main_t * vm,
+					   ip6_address_t * start,
+					   ip6_address_t * end, u32 table_id);
 
-  f64 srtt = clib_min ((f64) tc->srtt * TCP_TICK, tc->mrtt_us);
+clib_error_t *vnet_tcp_enable_disable (vlib_main_t * vm, u8 is_en);
 
-  /* TODO should constrain to interface's max throughput but
-   * we don't have link speeds for sw ifs ..*/
-  return ((f64) tc->cwnd / srtt);
-}
+format_function_t format_tcp_state;
+format_function_t format_tcp_flags;
+format_function_t format_tcp_sacks;
+format_function_t format_tcp_rcv_sacks;
+format_function_t format_tcp_connection;
+format_function_t format_tcp_connection_id;
 
 always_inline void
 tcp_timer_set (tcp_connection_t * tc, u8 timer_id, u32 interval)
@@ -1287,101 +467,6 @@ tcp_timer_is_active (tcp_connection_t * tc, tcp_timers_e timer)
   ASSERT(_tc->state != TCP_STATE_ESTABLISHED 				\
 	 || transport_max_tx_dequeue (&_tc->connection) >= _a)
 
-void tcp_rcv_sacks (tcp_connection_t * tc, u32 ack);
-u8 *tcp_scoreboard_replay (u8 * s, tcp_connection_t * tc, u8 verbose);
-
-/**
- * Register exiting cc algo type
- */
-void tcp_cc_algo_register (tcp_cc_algorithm_type_e type,
-			   const tcp_cc_algorithm_t * vft);
-
-/**
- * Register new cc algo type
- */
-tcp_cc_algorithm_type_e tcp_cc_algo_new_type (const tcp_cc_algorithm_t * vft);
-tcp_cc_algorithm_t *tcp_cc_algo_get (tcp_cc_algorithm_type_e type);
-
-static inline void *
-tcp_cc_data (tcp_connection_t * tc)
-{
-  return (void *) tc->cc_data;
-}
-
-void newreno_rcv_cong_ack (tcp_connection_t * tc, tcp_cc_ack_t ack_type,
-			   tcp_rate_sample_t * rs);
-/**
- * Initialize connection by gleaning network and rcv params from buffer
- *
- * @param tc		connection to initialize
- * @param b		buffer whose current data is pointing at ip
- * @param is_ip4	flag set to 1 if using ip4
- */
-void tcp_init_w_buffer (tcp_connection_t * tc, vlib_buffer_t * b, u8 is_ip4);
-
-/**
- * Push TCP header to buffer
- *
- * @param vm - vlib_main
- * @param b - buffer to write the header to
- * @param sp_net - source port net order
- * @param dp_net - destination port net order
- * @param seq - sequence number net order
- * @param ack - ack number net order
- * @param tcp_hdr_opts_len - header and options length in bytes
- * @param flags - header flags
- * @param wnd - window size
- *
- * @return - pointer to start of TCP header
- */
-always_inline void *
-vlib_buffer_push_tcp_net_order (vlib_buffer_t * b, u16 sp, u16 dp, u32 seq,
-				u32 ack, u8 tcp_hdr_opts_len, u8 flags,
-				u16 wnd)
-{
-  tcp_header_t *th;
-
-  th = vlib_buffer_push_uninit (b, tcp_hdr_opts_len);
-
-  th->src_port = sp;
-  th->dst_port = dp;
-  th->seq_number = seq;
-  th->ack_number = ack;
-  th->data_offset_and_reserved = (tcp_hdr_opts_len >> 2) << 4;
-  th->flags = flags;
-  th->window = wnd;
-  th->checksum = 0;
-  th->urgent_pointer = 0;
-  vnet_buffer (b)->l4_hdr_offset = (u8 *) th - b->data;
-  b->flags |= VNET_BUFFER_F_L4_HDR_OFFSET_VALID;
-  return th;
-}
-
-/**
- * Push TCP header to buffer
- *
- * @param b - buffer to write the header to
- * @param sp_net - source port net order
- * @param dp_net - destination port net order
- * @param seq - sequence number host order
- * @param ack - ack number host order
- * @param tcp_hdr_opts_len - header and options length in bytes
- * @param flags - header flags
- * @param wnd - window size
- *
- * @return - pointer to start of TCP header
- */
-always_inline void *
-vlib_buffer_push_tcp (vlib_buffer_t * b, u16 sp_net, u16 dp_net, u32 seq,
-		      u32 ack, u8 tcp_hdr_opts_len, u8 flags, u16 wnd)
-{
-  return vlib_buffer_push_tcp_net_order (b, sp_net, dp_net,
-					 clib_host_to_net_u32 (seq),
-					 clib_host_to_net_u32 (ack),
-					 tcp_hdr_opts_len, flags,
-					 clib_host_to_net_u16 (wnd));
-}
-
 #endif /* _vnet_tcp_h_ */
 
 /*
diff --git a/src/vnet/tcp/tcp_api.c b/src/vnet/tcp/tcp_api.c
index ac4314f0e83..8b169f8f1e3 100644
--- a/src/vnet/tcp/tcp_api.c
+++ b/src/vnet/tcp/tcp_api.c
@@ -115,11 +115,6 @@ tcp_api_hookup (vlib_main_t * vm)
 
 VLIB_API_INIT_FUNCTION (tcp_api_hookup);
 
-void
-tcp_api_reference (void)
-{
-}
-
 /*
  * fd.io coding-style-patch-verification: ON
  *
diff --git a/src/vnet/tcp/tcp_bt.c b/src/vnet/tcp/tcp_bt.c
index e8dc5c9c068..6f9ee0168f7 100644
--- a/src/vnet/tcp/tcp_bt.c
+++ b/src/vnet/tcp/tcp_bt.c
@@ -16,7 +16,9 @@
  * draft-cheng-iccrg-delivery-rate-estimation-00
  */
 
+#include <vnet/tcp/tcp_bt.h>
 #include <vnet/tcp/tcp.h>
+#include <vnet/tcp/tcp_inlines.h>
 
 static tcp_bt_sample_t *
 bt_get_sample (tcp_byte_tracker_t * bt, u32 bts_index)
diff --git a/src/vnet/tcp/tcp_bt.h b/src/vnet/tcp/tcp_bt.h
new file mode 100644
index 00000000000..b9d0e571a5d
--- /dev/null
+++ b/src/vnet/tcp/tcp_bt.h
@@ -0,0 +1,91 @@
+/*
+ * Copyright (c) 2020 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/*
+ * Rate estimation
+ */
+
+#ifndef SRC_VNET_TCP_TCP_BT_H_
+#define SRC_VNET_TCP_TCP_BT_H_
+
+#include <vnet/tcp/tcp_types.h>
+
+/**
+ * Byte tracker initialize
+ *
+ * @param tc	connection for which the byte tracker should be allocated and
+ * 		initialized
+ */
+void tcp_bt_init (tcp_connection_t * tc);
+/**
+ * Byte tracker cleanup
+ *
+ * @param tc	connection for which the byte tracker should be cleaned up
+ */
+void tcp_bt_cleanup (tcp_connection_t * tc);
+/**
+ * Flush byte tracker samples
+ *
+ * @param tc	tcp connection for which samples should be flushed
+ */
+void tcp_bt_flush_samples (tcp_connection_t * tc);
+/**
+ * Track a tcp tx burst
+ *
+ * @param tc	tcp connection
+ */
+void tcp_bt_track_tx (tcp_connection_t * tc, u32 len);
+/**
+ * Track a tcp retransmission
+ *
+ * @param tc	tcp connection
+ * @param start	start sequence number
+ * @param end	end sequence number
+ */
+void tcp_bt_track_rxt (tcp_connection_t * tc, u32 start, u32 end);
+/**
+ * Generate a delivery rate sample from recently acked bytes
+ *
+ * @param tc	tcp connection
+ * @param rs	resulting rate sample
+ */
+void tcp_bt_sample_delivery_rate (tcp_connection_t * tc,
+				  tcp_rate_sample_t * rs);
+/**
+ * Check if sample to be generated is app limited
+ *
+ * @param tc	tcp connection
+ */
+void tcp_bt_check_app_limited (tcp_connection_t * tc);
+/**
+ * Check if the byte tracker is in sane state
+ *
+ * Should be used only for testing
+ *
+ * @param bt	byte tracker
+ */
+int tcp_bt_is_sane (tcp_byte_tracker_t * bt);
+
+format_function_t format_tcp_bt;
+
+#endif /* SRC_VNET_TCP_TCP_BT_H_ */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/vnet/tcp/tcp_cc.h b/src/vnet/tcp/tcp_cc.h
new file mode 100644
index 00000000000..54d2dc6334b
--- /dev/null
+++ b/src/vnet/tcp/tcp_cc.h
@@ -0,0 +1,111 @@
+/*
+ * Copyright (c) 2020 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef SRC_VNET_TCP_TCP_CC_H_
+#define SRC_VNET_TCP_TCP_CC_H_
+
+#include <vnet/tcp/tcp_types.h>
+
+always_inline void
+tcp_cc_rcv_ack (tcp_connection_t * tc, tcp_rate_sample_t * rs)
+{
+  tc->cc_algo->rcv_ack (tc, rs);
+  tc->tsecr_last_ack = tc->rcv_opts.tsecr;
+}
+
+static inline void
+tcp_cc_rcv_cong_ack (tcp_connection_t * tc, tcp_cc_ack_t ack_type,
+		     tcp_rate_sample_t * rs)
+{
+  tc->cc_algo->rcv_cong_ack (tc, ack_type, rs);
+}
+
+static inline void
+tcp_cc_congestion (tcp_connection_t * tc)
+{
+  tc->cc_algo->congestion (tc);
+}
+
+static inline void
+tcp_cc_loss (tcp_connection_t * tc)
+{
+  tc->cc_algo->loss (tc);
+}
+
+static inline void
+tcp_cc_recovered (tcp_connection_t * tc)
+{
+  tc->cc_algo->recovered (tc);
+}
+
+static inline void
+tcp_cc_undo_recovery (tcp_connection_t * tc)
+{
+  if (tc->cc_algo->undo_recovery)
+    tc->cc_algo->undo_recovery (tc);
+}
+
+static inline void
+tcp_cc_event (tcp_connection_t * tc, tcp_cc_event_t evt)
+{
+  if (tc->cc_algo->event)
+    tc->cc_algo->event (tc, evt);
+}
+
+static inline u64
+tcp_cc_get_pacing_rate (tcp_connection_t * tc)
+{
+  if (tc->cc_algo->get_pacing_rate)
+    return tc->cc_algo->get_pacing_rate (tc);
+
+  f64 srtt = clib_min ((f64) tc->srtt * TCP_TICK, tc->mrtt_us);
+
+  /* TODO should constrain to interface's max throughput but
+   * we don't have link speeds for sw ifs ..*/
+  return ((f64) tc->cwnd / srtt);
+}
+
+static inline void *
+tcp_cc_data (tcp_connection_t * tc)
+{
+  return (void *) tc->cc_data;
+}
+
+/**
+ * Register exiting cc algo type
+ */
+void tcp_cc_algo_register (tcp_cc_algorithm_type_e type,
+			   const tcp_cc_algorithm_t * vft);
+
+/**
+ * Register new cc algo type
+ */
+tcp_cc_algorithm_type_e tcp_cc_algo_new_type (const tcp_cc_algorithm_t * vft);
+tcp_cc_algorithm_t *tcp_cc_algo_get (tcp_cc_algorithm_type_e type);
+
+
+void newreno_rcv_cong_ack (tcp_connection_t * tc, tcp_cc_ack_t ack_type,
+			   tcp_rate_sample_t * rs);
+
+
+#endif /* SRC_VNET_TCP_TCP_CC_H_ */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/vnet/tcp/tcp_cli.c b/src/vnet/tcp/tcp_cli.c
new file mode 100644
index 00000000000..a28e2c83659
--- /dev/null
+++ b/src/vnet/tcp/tcp_cli.c
@@ -0,0 +1,1030 @@
+/*
+ * Copyright (c) 2020 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <vnet/tcp/tcp.h>
+#include <vnet/tcp/tcp_inlines.h>
+#include <vnet/dpo/receive_dpo.h>
+#include <vnet/ip-neighbor/ip_neighbor.h>
+
+const char *tcp_fsm_states[] = {
+#define _(sym, str) str,
+  foreach_tcp_fsm_state
+#undef _
+};
+
+u8 *
+format_tcp_state (u8 * s, va_list * args)
+{
+  u32 state = va_arg (*args, u32);
+
+  if (state < TCP_N_STATES)
+    s = format (s, "%s", tcp_fsm_states[state]);
+  else
+    s = format (s, "UNKNOWN (%d (0x%x))", state, state);
+  return s;
+}
+
+const char *tcp_cfg_flags_str[] = {
+#define _(sym, str) str,
+  foreach_tcp_cfg_flag
+#undef _
+};
+
+static u8 *
+format_tcp_cfg_flags (u8 * s, va_list * args)
+{
+  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
+  int i, last = -1;
+
+  for (i = 0; i < TCP_CFG_N_FLAG_BITS; i++)
+    if (tc->cfg_flags & (1 << i))
+      last = i;
+  for (i = 0; i < last; i++)
+    {
+      if (tc->cfg_flags & (1 << i))
+	s = format (s, "%s, ", tcp_cfg_flags_str[i]);
+    }
+  if (last >= 0)
+    s = format (s, "%s", tcp_cfg_flags_str[last]);
+  return s;
+}
+
+const char *tcp_connection_flags_str[] = {
+#define _(sym, str) str,
+  foreach_tcp_connection_flag
+#undef _
+};
+
+static u8 *
+format_tcp_connection_flags (u8 * s, va_list * args)
+{
+  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
+  int i, last = -1;
+
+  for (i = 0; i < TCP_CONN_N_FLAG_BITS; i++)
+    if (tc->flags & (1 << i))
+      last = i;
+  for (i = 0; i < last; i++)
+    {
+      if (tc->flags & (1 << i))
+	s = format (s, "%s, ", tcp_connection_flags_str[i]);
+    }
+  if (last >= 0)
+    s = format (s, "%s", tcp_connection_flags_str[last]);
+  return s;
+}
+
+const char *tcp_conn_timers[] = {
+#define _(sym, str) str,
+  foreach_tcp_timer
+#undef _
+};
+
+static u8 *
+format_tcp_timers (u8 * s, va_list * args)
+{
+  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
+  int i, last = -1;
+
+  for (i = 0; i < TCP_N_TIMERS; i++)
+    if (tc->timers[i] != TCP_TIMER_HANDLE_INVALID)
+      last = i;
+
+  for (i = 0; i < last; i++)
+    {
+      if (tc->timers[i] != TCP_TIMER_HANDLE_INVALID)
+	s = format (s, "%s,", tcp_conn_timers[i]);
+    }
+
+  if (last >= 0)
+    s = format (s, "%s", tcp_conn_timers[i]);
+
+  return s;
+}
+
+static u8 *
+format_tcp_congestion_status (u8 * s, va_list * args)
+{
+  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
+  if (tcp_in_recovery (tc))
+    s = format (s, "recovery");
+  else if (tcp_in_fastrecovery (tc))
+    s = format (s, "fastrecovery");
+  else
+    s = format (s, "none");
+  return s;
+}
+
+static i32
+tcp_rcv_wnd_available (tcp_connection_t * tc)
+{
+  return (i32) tc->rcv_wnd - (tc->rcv_nxt - tc->rcv_las);
+}
+
+static u8 *
+format_tcp_congestion (u8 * s, va_list * args)
+{
+  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
+  u32 indent = format_get_indent (s), prr_space = 0;
+
+  s = format (s, "%U ", format_tcp_congestion_status, tc);
+  s = format (s, "algo %s cwnd %u ssthresh %u bytes_acked %u\n",
+	      tc->cc_algo->name, tc->cwnd, tc->ssthresh, tc->bytes_acked);
+  s = format (s, "%Ucc space %u prev_cwnd %u prev_ssthresh %u\n",
+	      format_white_space, indent, tcp_available_cc_snd_space (tc),
+	      tc->prev_cwnd, tc->prev_ssthresh);
+  s = format (s, "%Usnd_cong %u dupack %u limited_tx %u\n",
+	      format_white_space, indent, tc->snd_congestion - tc->iss,
+	      tc->rcv_dupacks, tc->limited_transmit - tc->iss);
+  s = format (s, "%Urxt_bytes %u rxt_delivered %u rxt_head %u rxt_ts %u\n",
+	      format_white_space, indent, tc->snd_rxt_bytes,
+	      tc->rxt_delivered, tc->rxt_head - tc->iss,
+	      tcp_time_now_w_thread (tc->c_thread_index) - tc->snd_rxt_ts);
+  if (tcp_in_fastrecovery (tc))
+    prr_space = tcp_fastrecovery_prr_snd_space (tc);
+  s = format (s, "%Uprr_start %u prr_delivered %u prr space %u\n",
+	      format_white_space, indent, tc->prr_start - tc->iss,
+	      tc->prr_delivered, prr_space);
+  return s;
+}
+
+static u8 *
+format_tcp_stats (u8 * s, va_list * args)
+{
+  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
+  u32 indent = format_get_indent (s);
+  s = format (s, "in segs %lu dsegs %lu bytes %lu dupacks %u\n",
+	      tc->segs_in, tc->data_segs_in, tc->bytes_in, tc->dupacks_in);
+  s = format (s, "%Uout segs %lu dsegs %lu bytes %lu dupacks %u\n",
+	      format_white_space, indent, tc->segs_out,
+	      tc->data_segs_out, tc->bytes_out, tc->dupacks_out);
+  s = format (s, "%Ufr %u tr %u rxt segs %lu bytes %lu duration %.3f\n",
+	      format_white_space, indent, tc->fr_occurences,
+	      tc->tr_occurences, tc->segs_retrans, tc->bytes_retrans,
+	      tcp_time_now_us (tc->c_thread_index) - tc->start_ts);
+  s = format (s, "%Uerr wnd data below %u above %u ack below %u above %u",
+	      format_white_space, indent, tc->errors.below_data_wnd,
+	      tc->errors.above_data_wnd, tc->errors.below_ack_wnd,
+	      tc->errors.above_ack_wnd);
+  return s;
+}
+
+static u8 *
+format_tcp_vars (u8 * s, va_list * args)
+{
+  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
+  s = format (s, " index: %u cfg: %U flags: %U timers: %U\n", tc->c_c_index,
+	      format_tcp_cfg_flags, tc, format_tcp_connection_flags, tc,
+	      format_tcp_timers, tc);
+  s = format (s, " snd_una %u snd_nxt %u snd_una_max %u",
+	      tc->snd_una - tc->iss, tc->snd_nxt - tc->iss,
+	      tc->snd_una_max - tc->iss);
+  s = format (s, " rcv_nxt %u rcv_las %u\n",
+	      tc->rcv_nxt - tc->irs, tc->rcv_las - tc->irs);
+  s = format (s, " snd_wnd %u rcv_wnd %u rcv_wscale %u ",
+	      tc->snd_wnd, tc->rcv_wnd, tc->rcv_wscale);
+  s = format (s, "snd_wl1 %u snd_wl2 %u\n", tc->snd_wl1 - tc->irs,
+	      tc->snd_wl2 - tc->iss);
+  s = format (s, " flight size %u out space %u rcv_wnd_av %u",
+	      tcp_flight_size (tc), tcp_available_output_snd_space (tc),
+	      tcp_rcv_wnd_available (tc));
+  s = format (s, " tsval_recent %u\n", tc->tsval_recent);
+  s = format (s, " tsecr %u tsecr_last_ack %u tsval_recent_age %u",
+	      tc->rcv_opts.tsecr, tc->tsecr_last_ack,
+	      tcp_time_now () - tc->tsval_recent_age);
+  s = format (s, " snd_mss %u\n", tc->snd_mss);
+  s = format (s, " rto %u rto_boff %u srtt %u us %.3f rttvar %u rtt_ts %.4f",
+	      tc->rto, tc->rto_boff, tc->srtt, tc->mrtt_us * 1000, tc->rttvar,
+	      tc->rtt_ts);
+  s = format (s, " rtt_seq %u\n", tc->rtt_seq - tc->iss);
+  s = format (s, " next_node %u opaque 0x%x fib_index %u\n",
+	      tc->next_node_index, tc->next_node_opaque, tc->c_fib_index);
+  s = format (s, " cong:   %U", format_tcp_congestion, tc);
+
+  if (tc->state >= TCP_STATE_ESTABLISHED)
+    {
+      s = format (s, " sboard: %U\n", format_tcp_scoreboard, &tc->sack_sb,
+		  tc);
+      s = format (s, " stats: %U\n", format_tcp_stats, tc);
+    }
+  if (vec_len (tc->snd_sacks))
+    s = format (s, " sacks tx: %U\n", format_tcp_sacks, tc);
+
+  return s;
+}
+
+u8 *
+format_tcp_connection_id (u8 * s, va_list * args)
+{
+  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
+  if (!tc)
+    return s;
+  if (tc->c_is_ip4)
+    {
+      s = format (s, "[%d:%d][%s] %U:%d->%U:%d", tc->c_thread_index,
+		  tc->c_s_index, "T", format_ip4_address, &tc->c_lcl_ip4,
+		  clib_net_to_host_u16 (tc->c_lcl_port), format_ip4_address,
+		  &tc->c_rmt_ip4, clib_net_to_host_u16 (tc->c_rmt_port));
+    }
+  else
+    {
+      s = format (s, "[%d:%d][%s] %U:%d->%U:%d", tc->c_thread_index,
+		  tc->c_s_index, "T", format_ip6_address, &tc->c_lcl_ip6,
+		  clib_net_to_host_u16 (tc->c_lcl_port), format_ip6_address,
+		  &tc->c_rmt_ip6, clib_net_to_host_u16 (tc->c_rmt_port));
+    }
+
+  return s;
+}
+
+u8 *
+format_tcp_connection (u8 * s, va_list * args)
+{
+  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
+  u32 verbose = va_arg (*args, u32);
+
+  if (!tc)
+    return s;
+  s = format (s, "%-50U", format_tcp_connection_id, tc);
+  if (verbose)
+    {
+      s = format (s, "%-15U", format_tcp_state, tc->state);
+      if (verbose > 1)
+	s = format (s, "\n%U", format_tcp_vars, tc);
+    }
+
+  return s;
+}
+
+u8 *
+format_tcp_sacks (u8 * s, va_list * args)
+{
+  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
+  sack_block_t *sacks = tc->snd_sacks;
+  sack_block_t *block;
+  int i, len = 0;
+
+  len = vec_len (sacks);
+  for (i = 0; i < len - 1; i++)
+    {
+      block = &sacks[i];
+      s = format (s, " start %u end %u\n", block->start - tc->irs,
+		  block->end - tc->irs);
+    }
+  if (len)
+    {
+      block = &sacks[len - 1];
+      s = format (s, " start %u end %u", block->start - tc->irs,
+		  block->end - tc->irs);
+    }
+  return s;
+}
+
+u8 *
+format_tcp_rcv_sacks (u8 * s, va_list * args)
+{
+  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
+  sack_block_t *sacks = tc->rcv_opts.sacks;
+  sack_block_t *block;
+  int i, len = 0;
+
+  len = vec_len (sacks);
+  for (i = 0; i < len - 1; i++)
+    {
+      block = &sacks[i];
+      s = format (s, " start %u end %u\n", block->start - tc->iss,
+		  block->end - tc->iss);
+    }
+  if (len)
+    {
+      block = &sacks[len - 1];
+      s = format (s, " start %u end %u", block->start - tc->iss,
+		  block->end - tc->iss);
+    }
+  return s;
+}
+
+static u8 *
+format_tcp_sack_hole (u8 * s, va_list * args)
+{
+  sack_scoreboard_hole_t *hole = va_arg (*args, sack_scoreboard_hole_t *);
+  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
+  if (tc)
+    s = format (s, "  [%u, %u]", hole->start - tc->iss, hole->end - tc->iss);
+  else
+    s = format (s, "  [%u, %u]", hole->start, hole->end);
+  return s;
+}
+
+u8 *
+format_tcp_scoreboard (u8 * s, va_list * args)
+{
+  sack_scoreboard_t *sb = va_arg (*args, sack_scoreboard_t *);
+  tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
+  sack_scoreboard_hole_t *hole;
+  u32 indent = format_get_indent (s);
+
+  s = format (s, "sacked %u last_sacked %u lost %u last_lost %u"
+	      " rxt_sacked %u\n",
+	      sb->sacked_bytes, sb->last_sacked_bytes, sb->lost_bytes,
+	      sb->last_lost_bytes, sb->rxt_sacked);
+  s = format (s, "%Ulast_delivered %u high_sacked %u is_reneging %u\n",
+	      format_white_space, indent, sb->last_bytes_delivered,
+	      sb->high_sacked - tc->iss, sb->is_reneging);
+  s = format (s, "%Ucur_rxt_hole %u high_rxt %u rescue_rxt %u",
+	      format_white_space, indent, sb->cur_rxt_hole,
+	      sb->high_rxt - tc->iss, sb->rescue_rxt - tc->iss);
+
+  hole = scoreboard_first_hole (sb);
+  if (hole)
+    s = format (s, "\n%Uhead %u tail %u %u holes:\n%U", format_white_space,
+		indent, sb->head, sb->tail, pool_elts (sb->holes),
+		format_white_space, indent);
+
+  while (hole)
+    {
+      s = format (s, "%U", format_tcp_sack_hole, hole, tc);
+      hole = scoreboard_next_hole (sb, hole);
+    }
+
+  return s;
+}
+
+/**
+ * \brief Configure an ipv4 source address range
+ * @param vm vlib_main_t pointer
+ * @param start first ipv4 address in the source address range
+ * @param end last ipv4 address in the source address range
+ * @param table_id VRF / table ID, 0 for the default FIB
+ * @return 0 if all OK, else an error indication from api_errno.h
+ */
+
+int
+tcp_configure_v4_source_address_range (vlib_main_t * vm,
+				       ip4_address_t * start,
+				       ip4_address_t * end, u32 table_id)
+{
+  u32 start_host_byte_order, end_host_byte_order;
+  fib_prefix_t prefix;
+  fib_node_index_t fei;
+  u32 fib_index = 0;
+  u32 sw_if_index;
+  int rv;
+
+  clib_memset (&prefix, 0, sizeof (prefix));
+
+  fib_index = fib_table_find (FIB_PROTOCOL_IP4, table_id);
+
+  if (fib_index == ~0)
+    return VNET_API_ERROR_NO_SUCH_FIB;
+
+  start_host_byte_order = clib_net_to_host_u32 (start->as_u32);
+  end_host_byte_order = clib_net_to_host_u32 (end->as_u32);
+
+  /* sanity check for reversed args or some such */
+  if ((end_host_byte_order - start_host_byte_order) > (10 << 10))
+    return VNET_API_ERROR_INVALID_ARGUMENT;
+
+  /* Lookup the last address, to identify the interface involved */
+  prefix.fp_len = 32;
+  prefix.fp_proto = FIB_PROTOCOL_IP4;
+  memcpy (&prefix.fp_addr.ip4, end, sizeof (ip4_address_t));
+
+  fei = fib_table_lookup (fib_index, &prefix);
+
+  /* Couldn't find route to destination. Bail out. */
+  if (fei == FIB_NODE_INDEX_INVALID)
+    return VNET_API_ERROR_NEXT_HOP_NOT_IN_FIB;
+
+  sw_if_index = fib_entry_get_resolving_interface (fei);
+
+  /* Configure proxy arp across the range */
+  rv = ip4_neighbor_proxy_add (fib_index, start, end);
+
+  if (rv)
+    return rv;
+
+  rv = ip4_neighbor_proxy_enable (sw_if_index);
+
+  if (rv)
+    return rv;
+
+  do
+    {
+      dpo_id_t dpo = DPO_INVALID;
+
+      vec_add1 (tcp_cfg.ip4_src_addrs, start[0]);
+
+      /* Add local adjacencies for the range */
+
+      receive_dpo_add_or_lock (DPO_PROTO_IP4, ~0 /* sw_if_index */ ,
+			       NULL, &dpo);
+      prefix.fp_len = 32;
+      prefix.fp_proto = FIB_PROTOCOL_IP4;
+      prefix.fp_addr.ip4.as_u32 = start->as_u32;
+
+      fib_table_entry_special_dpo_update (fib_index,
+					  &prefix,
+					  FIB_SOURCE_API,
+					  FIB_ENTRY_FLAG_EXCLUSIVE, &dpo);
+      dpo_reset (&dpo);
+
+      start_host_byte_order++;
+      start->as_u32 = clib_host_to_net_u32 (start_host_byte_order);
+    }
+  while (start_host_byte_order <= end_host_byte_order);
+
+  return 0;
+}
+
+/**
+ * \brief Configure an ipv6 source address range
+ * @param vm vlib_main_t pointer
+ * @param start first ipv6 address in the source address range
+ * @param end last ipv6 address in the source address range
+ * @param table_id VRF / table ID, 0 for the default FIB
+ * @return 0 if all OK, else an error indication from api_errno.h
+ */
+
+int
+tcp_configure_v6_source_address_range (vlib_main_t * vm,
+				       ip6_address_t * start,
+				       ip6_address_t * end, u32 table_id)
+{
+  fib_prefix_t prefix;
+  u32 fib_index = 0;
+  fib_node_index_t fei;
+  u32 sw_if_index;
+
+  clib_memset (&prefix, 0, sizeof (prefix));
+
+  fib_index = fib_table_find (FIB_PROTOCOL_IP6, table_id);
+
+  if (fib_index == ~0)
+    return VNET_API_ERROR_NO_SUCH_FIB;
+
+  while (1)
+    {
+      int i;
+      ip6_address_t tmp;
+      dpo_id_t dpo = DPO_INVALID;
+
+      /* Remember this address */
+      vec_add1 (tcp_cfg.ip6_src_addrs, start[0]);
+
+      /* Lookup the prefix, to identify the interface involved */
+      prefix.fp_len = 128;
+      prefix.fp_proto = FIB_PROTOCOL_IP6;
+      memcpy (&prefix.fp_addr.ip6, start, sizeof (ip6_address_t));
+
+      fei = fib_table_lookup (fib_index, &prefix);
+
+      /* Couldn't find route to destination. Bail out. */
+      if (fei == FIB_NODE_INDEX_INVALID)
+	return VNET_API_ERROR_NEXT_HOP_NOT_IN_FIB;
+
+      sw_if_index = fib_entry_get_resolving_interface (fei);
+
+      if (sw_if_index == (u32) ~ 0)
+	return VNET_API_ERROR_NO_MATCHING_INTERFACE;
+
+      /* Add a proxy neighbor discovery entry for this address */
+      ip6_neighbor_proxy_add (sw_if_index, start);
+
+      /* Add a receive adjacency for this address */
+      receive_dpo_add_or_lock (DPO_PROTO_IP6, ~0 /* sw_if_index */ ,
+			       NULL, &dpo);
+
+      fib_table_entry_special_dpo_update (fib_index,
+					  &prefix,
+					  FIB_SOURCE_API,
+					  FIB_ENTRY_FLAG_EXCLUSIVE, &dpo);
+      dpo_reset (&dpo);
+
+      /* Done with the entire range? */
+      if (!memcmp (start, end, sizeof (start[0])))
+	break;
+
+      /* Increment the address. DGMS. */
+      tmp = start[0];
+      for (i = 15; i >= 0; i--)
+	{
+	  tmp.as_u8[i] += 1;
+	  if (tmp.as_u8[i] != 0)
+	    break;
+	}
+      start[0] = tmp;
+    }
+  return 0;
+}
+
+static clib_error_t *
+tcp_src_address_fn (vlib_main_t * vm,
+		    unformat_input_t * input, vlib_cli_command_t * cmd_arg)
+{
+  ip4_address_t v4start, v4end;
+  ip6_address_t v6start, v6end;
+  u32 table_id = 0;
+  int v4set = 0;
+  int v6set = 0;
+  int rv;
+
+  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (input, "%U - %U", unformat_ip4_address, &v4start,
+		    unformat_ip4_address, &v4end))
+	v4set = 1;
+      else if (unformat (input, "%U", unformat_ip4_address, &v4start))
+	{
+	  memcpy (&v4end, &v4start, sizeof (v4start));
+	  v4set = 1;
+	}
+      else if (unformat (input, "%U - %U", unformat_ip6_address, &v6start,
+			 unformat_ip6_address, &v6end))
+	v6set = 1;
+      else if (unformat (input, "%U", unformat_ip6_address, &v6start))
+	{
+	  memcpy (&v6end, &v6start, sizeof (v6start));
+	  v6set = 1;
+	}
+      else if (unformat (input, "fib-table %d", &table_id))
+	;
+      else
+	break;
+    }
+
+  if (!v4set && !v6set)
+    return clib_error_return (0, "at least one v4 or v6 address required");
+
+  if (v4set)
+    {
+      rv = tcp_configure_v4_source_address_range (vm, &v4start, &v4end,
+						  table_id);
+      switch (rv)
+	{
+	case 0:
+	  break;
+
+	case VNET_API_ERROR_NO_SUCH_FIB:
+	  return clib_error_return (0, "Invalid table-id %d", table_id);
+
+	case VNET_API_ERROR_INVALID_ARGUMENT:
+	  return clib_error_return (0, "Invalid address range %U - %U",
+				    format_ip4_address, &v4start,
+				    format_ip4_address, &v4end);
+	default:
+	  return clib_error_return (0, "error %d", rv);
+	  break;
+	}
+    }
+  if (v6set)
+    {
+      rv = tcp_configure_v6_source_address_range (vm, &v6start, &v6end,
+						  table_id);
+      switch (rv)
+	{
+	case 0:
+	  break;
+
+	case VNET_API_ERROR_NO_SUCH_FIB:
+	  return clib_error_return (0, "Invalid table-id %d", table_id);
+
+	default:
+	  return clib_error_return (0, "error %d", rv);
+	  break;
+	}
+    }
+  return 0;
+}
+
+/* *INDENT-OFF* */
+VLIB_CLI_COMMAND (tcp_src_address_command, static) =
+{
+  .path = "tcp src-address",
+  .short_help = "tcp src-address <ip-addr> [- <ip-addr>] add src address range",
+  .function = tcp_src_address_fn,
+};
+/* *INDENT-ON* */
+
+static u8 *
+tcp_scoreboard_dump_trace (u8 * s, sack_scoreboard_t * sb)
+{
+#if TCP_SCOREBOARD_TRACE
+
+  scoreboard_trace_elt_t *block;
+  int i = 0;
+
+  if (!sb->trace)
+    return s;
+
+  s = format (s, "scoreboard trace:");
+  vec_foreach (block, sb->trace)
+  {
+    s = format (s, "{%u, %u, %u, %u, %u}, ", block->start, block->end,
+		block->ack, block->snd_una_max, block->group);
+    if ((++i % 3) == 0)
+      s = format (s, "\n");
+  }
+  return s;
+#else
+  return 0;
+#endif
+}
+
+static clib_error_t *
+tcp_show_scoreboard_trace_fn (vlib_main_t * vm, unformat_input_t * input,
+			      vlib_cli_command_t * cmd_arg)
+{
+  transport_connection_t *tconn = 0;
+  tcp_connection_t *tc;
+  u8 *s = 0;
+  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (input, "%U", unformat_transport_connection, &tconn,
+		    TRANSPORT_PROTO_TCP))
+	;
+      else
+	return clib_error_return (0, "unknown input `%U'",
+				  format_unformat_error, input);
+    }
+
+  if (!TCP_SCOREBOARD_TRACE)
+    {
+      vlib_cli_output (vm, "scoreboard tracing not enabled");
+      return 0;
+    }
+
+  tc = tcp_get_connection_from_transport (tconn);
+  s = tcp_scoreboard_dump_trace (s, &tc->sack_sb);
+  vlib_cli_output (vm, "%v", s);
+  return 0;
+}
+
+/* *INDENT-OFF* */
+VLIB_CLI_COMMAND (tcp_show_scoreboard_trace_command, static) =
+{
+  .path = "show tcp scoreboard trace",
+  .short_help = "show tcp scoreboard trace <connection>",
+  .function = tcp_show_scoreboard_trace_fn,
+};
+/* *INDENT-ON* */
+
+u8 *
+tcp_scoreboard_replay (u8 * s, tcp_connection_t * tc, u8 verbose)
+{
+  int i, trace_len;
+  scoreboard_trace_elt_t *trace;
+  u32 next_ack, left, group, has_new_ack = 0;
+  tcp_connection_t _dummy_tc, *dummy_tc = &_dummy_tc;
+  sack_block_t *block;
+
+  if (!TCP_SCOREBOARD_TRACE)
+    {
+      s = format (s, "scoreboard tracing not enabled");
+      return s;
+    }
+
+  if (!tc)
+    return s;
+
+  clib_memset (dummy_tc, 0, sizeof (*dummy_tc));
+  tcp_connection_timers_init (dummy_tc);
+  scoreboard_init (&dummy_tc->sack_sb);
+  dummy_tc->rcv_opts.flags |= TCP_OPTS_FLAG_SACK;
+
+#if TCP_SCOREBOARD_TRACE
+  trace = tc->sack_sb.trace;
+  trace_len = vec_len (tc->sack_sb.trace);
+#endif
+
+  for (i = 0; i < trace_len; i++)
+    {
+      if (trace[i].ack != 0)
+	{
+	  dummy_tc->snd_una = trace[i].ack - 1448;
+	  dummy_tc->snd_una_max = trace[i].ack;
+	}
+    }
+
+  left = 0;
+  while (left < trace_len)
+    {
+      group = trace[left].group;
+      vec_reset_length (dummy_tc->rcv_opts.sacks);
+      has_new_ack = 0;
+      while (trace[left].group == group)
+	{
+	  if (trace[left].ack != 0)
+	    {
+	      if (verbose)
+		s = format (s, "Adding ack %u, snd_una_max %u, segs: ",
+			    trace[left].ack, trace[left].snd_una_max);
+	      dummy_tc->snd_una_max = trace[left].snd_una_max;
+	      next_ack = trace[left].ack;
+	      has_new_ack = 1;
+	    }
+	  else
+	    {
+	      if (verbose)
+		s = format (s, "[%u, %u], ", trace[left].start,
+			    trace[left].end);
+	      vec_add2 (dummy_tc->rcv_opts.sacks, block, 1);
+	      block->start = trace[left].start;
+	      block->end = trace[left].end;
+	    }
+	  left++;
+	}
+
+      /* Push segments */
+      tcp_rcv_sacks (dummy_tc, next_ack);
+      if (has_new_ack)
+	dummy_tc->snd_una = next_ack;
+
+      if (verbose)
+	s = format (s, "result: %U", format_tcp_scoreboard,
+		    &dummy_tc->sack_sb);
+
+    }
+  s = format (s, "result: %U", format_tcp_scoreboard, &dummy_tc->sack_sb);
+
+  return s;
+}
+
+static clib_error_t *
+tcp_scoreboard_trace_fn (vlib_main_t * vm, unformat_input_t * input,
+			 vlib_cli_command_t * cmd_arg)
+{
+  transport_connection_t *tconn = 0;
+  tcp_connection_t *tc = 0;
+  u8 *str = 0;
+  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (input, "%U", unformat_transport_connection, &tconn,
+		    TRANSPORT_PROTO_TCP))
+	;
+      else
+	return clib_error_return (0, "unknown input `%U'",
+				  format_unformat_error, input);
+    }
+
+  if (!TCP_SCOREBOARD_TRACE)
+    {
+      vlib_cli_output (vm, "scoreboard tracing not enabled");
+      return 0;
+    }
+
+  tc = tcp_get_connection_from_transport (tconn);
+  if (!tc)
+    {
+      vlib_cli_output (vm, "connection not found");
+      return 0;
+    }
+  str = tcp_scoreboard_replay (str, tc, 1);
+  vlib_cli_output (vm, "%v", str);
+  return 0;
+}
+
+/* *INDENT-OFF* */
+VLIB_CLI_COMMAND (tcp_replay_scoreboard_command, static) =
+{
+  .path = "tcp replay scoreboard",
+  .short_help = "tcp replay scoreboard <connection>",
+  .function = tcp_scoreboard_trace_fn,
+};
+/* *INDENT-ON* */
+
+static clib_error_t *
+show_tcp_punt_fn (vlib_main_t * vm, unformat_input_t * input,
+		  vlib_cli_command_t * cmd_arg)
+{
+  tcp_main_t *tm = vnet_get_tcp_main ();
+  if (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    return clib_error_return (0, "unknown input `%U'", format_unformat_error,
+			      input);
+  vlib_cli_output (vm, "IPv4 TCP punt: %s",
+		   tm->punt_unknown4 ? "enabled" : "disabled");
+  vlib_cli_output (vm, "IPv6 TCP punt: %s",
+		   tm->punt_unknown6 ? "enabled" : "disabled");
+  return 0;
+}
+/* *INDENT-OFF* */
+VLIB_CLI_COMMAND (show_tcp_punt_command, static) =
+{
+  .path = "show tcp punt",
+  .short_help = "show tcp punt",
+  .function = show_tcp_punt_fn,
+};
+/* *INDENT-ON* */
+
+static clib_error_t *
+show_tcp_stats_fn (vlib_main_t * vm, unformat_input_t * input,
+		   vlib_cli_command_t * cmd)
+{
+  tcp_main_t *tm = vnet_get_tcp_main ();
+  tcp_worker_ctx_t *wrk;
+  u32 thread;
+
+  if (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    return clib_error_return (0, "unknown input `%U'", format_unformat_error,
+			      input);
+  for (thread = 0; thread < vec_len (tm->wrk_ctx); thread++)
+    {
+      wrk = tcp_get_worker (thread);
+      vlib_cli_output (vm, "Thread %u:\n", thread);
+
+      if (clib_fifo_elts (wrk->pending_timers))
+	vlib_cli_output (vm, " %lu pending timers",
+			 clib_fifo_elts (wrk->pending_timers));
+
+#define _(name,type,str)					\
+  if (wrk->stats.name)						\
+    vlib_cli_output (vm, " %lu %s", wrk->stats.name, str);
+      foreach_tcp_wrk_stat
+#undef _
+    }
+
+  return 0;
+}
+
+/* *INDENT-OFF* */
+VLIB_CLI_COMMAND (show_tcp_stats_command, static) =
+{
+  .path = "show tcp stats",
+  .short_help = "show tcp stats",
+  .function = show_tcp_stats_fn,
+};
+/* *INDENT-ON* */
+
+static clib_error_t *
+clear_tcp_stats_fn (vlib_main_t * vm, unformat_input_t * input,
+		    vlib_cli_command_t * cmd)
+{
+  tcp_main_t *tm = vnet_get_tcp_main ();
+  tcp_worker_ctx_t *wrk;
+  u32 thread;
+
+  if (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    return clib_error_return (0, "unknown input `%U'", format_unformat_error,
+			      input);
+
+  for (thread = 0; thread < vec_len (tm->wrk_ctx); thread++)
+    {
+      wrk = tcp_get_worker (thread);
+      clib_memset (&wrk->stats, 0, sizeof (wrk->stats));
+    }
+
+  return 0;
+}
+
+/* *INDENT-OFF* */
+VLIB_CLI_COMMAND (clear_tcp_stats_command, static) =
+{
+  .path = "clear tcp stats",
+  .short_help = "clear tcp stats",
+  .function = clear_tcp_stats_fn,
+};
+/* *INDENT-ON* */
+
+uword
+unformat_tcp_cc_algo (unformat_input_t * input, va_list * va)
+{
+  tcp_cc_algorithm_type_e *result = va_arg (*va, tcp_cc_algorithm_type_e *);
+  tcp_main_t *tm = &tcp_main;
+  char *cc_algo_name;
+  u8 found = 0;
+  uword *p;
+
+  if (unformat (input, "%s", &cc_algo_name)
+      && ((p = hash_get_mem (tm->cc_algo_by_name, cc_algo_name))))
+    {
+      *result = *p;
+      found = 1;
+    }
+
+  vec_free (cc_algo_name);
+  return found;
+}
+
+uword
+unformat_tcp_cc_algo_cfg (unformat_input_t * input, va_list * va)
+{
+  tcp_main_t *tm = vnet_get_tcp_main ();
+  tcp_cc_algorithm_t *cc_alg;
+  unformat_input_t sub_input;
+  int found = 0;
+
+  vec_foreach (cc_alg, tm->cc_algos)
+  {
+    if (!unformat (input, cc_alg->name))
+      continue;
+
+    if (cc_alg->unformat_cfg
+	&& unformat (input, "%U", unformat_vlib_cli_sub_input, &sub_input))
+      {
+	if (cc_alg->unformat_cfg (&sub_input))
+	  found = 1;
+      }
+  }
+  return found;
+}
+
+static clib_error_t *
+tcp_config_fn (vlib_main_t * vm, unformat_input_t * input)
+{
+  u32 cwnd_multiplier, tmp_time;
+  uword memory_size;
+
+  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (input, "preallocated-connections %d",
+		    &tcp_cfg.preallocated_connections))
+	;
+      else if (unformat (input, "preallocated-half-open-connections %d",
+			 &tcp_cfg.preallocated_half_open_connections))
+	;
+      else if (unformat (input, "buffer-fail-fraction %f",
+			 &tcp_cfg.buffer_fail_fraction))
+	;
+      else if (unformat (input, "max-rx-fifo %U", unformat_memory_size,
+			 &memory_size))
+	{
+	  if (memory_size >= 0x100000000)
+	    {
+	      return clib_error_return
+		(0, "max-rx-fifo %llu (0x%llx) too large", memory_size,
+		 memory_size);
+	    }
+	  tcp_cfg.max_rx_fifo = memory_size;
+	}
+      else if (unformat (input, "min-rx-fifo %U", unformat_memory_size,
+			 &memory_size))
+	{
+	  if (memory_size >= 0x100000000)
+	    {
+	      return clib_error_return
+		(0, "min-rx-fifo %llu (0x%llx) too large", memory_size,
+		 memory_size);
+	    }
+	  tcp_cfg.min_rx_fifo = memory_size;
+	}
+      else if (unformat (input, "mtu %u", &tcp_cfg.default_mtu))
+	;
+      else if (unformat (input, "rwnd-min-update-ack %d",
+			 &tcp_cfg.rwnd_min_update_ack))
+	;
+      else if (unformat (input, "initial-cwnd-multiplier %u",
+			 &cwnd_multiplier))
+	tcp_cfg.initial_cwnd_multiplier = cwnd_multiplier;
+      else if (unformat (input, "no-tx-pacing"))
+	tcp_cfg.enable_tx_pacing = 0;
+      else if (unformat (input, "tso"))
+	tcp_cfg.allow_tso = 1;
+      else if (unformat (input, "no-csum-offload"))
+	tcp_cfg.csum_offload = 0;
+      else if (unformat (input, "cc-algo %U", unformat_tcp_cc_algo,
+			 &tcp_cfg.cc_algo))
+	;
+      else if (unformat (input, "%U", unformat_tcp_cc_algo_cfg))
+	;
+      else if (unformat (input, "closewait-time %u", &tmp_time))
+	tcp_cfg.closewait_time = tmp_time / TCP_TIMER_TICK;
+      else if (unformat (input, "timewait-time %u", &tmp_time))
+	tcp_cfg.timewait_time = tmp_time / TCP_TIMER_TICK;
+      else if (unformat (input, "finwait1-time %u", &tmp_time))
+	tcp_cfg.finwait1_time = tmp_time / TCP_TIMER_TICK;
+      else if (unformat (input, "finwait2-time %u", &tmp_time))
+	tcp_cfg.finwait2_time = tmp_time / TCP_TIMER_TICK;
+      else if (unformat (input, "lastack-time %u", &tmp_time))
+	tcp_cfg.lastack_time = tmp_time / TCP_TIMER_TICK;
+      else if (unformat (input, "closing-time %u", &tmp_time))
+	tcp_cfg.closing_time = tmp_time / TCP_TIMER_TICK;
+      else if (unformat (input, "cleanup-time %u", &tmp_time))
+	tcp_cfg.cleanup_time = tmp_time / 1000.0;
+      else
+	return clib_error_return (0, "unknown input `%U'",
+				  format_unformat_error, input);
+    }
+  return 0;
+}
+
+VLIB_CONFIG_FUNCTION (tcp_config_fn, "tcp");
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/vnet/tcp/tcp_cubic.c b/src/vnet/tcp/tcp_cubic.c
index b79ef8342d3..b8ac80a8feb 100644
--- a/src/vnet/tcp/tcp_cubic.c
+++ b/src/vnet/tcp/tcp_cubic.c
@@ -14,6 +14,7 @@
  */
 
 #include <vnet/tcp/tcp.h>
+#include <vnet/tcp/tcp_inlines.h>
 #include <math.h>
 
 #define beta_cubic 	0.7
diff --git a/src/vnet/tcp/tcp_inlines.h b/src/vnet/tcp/tcp_inlines.h
new file mode 100644
index 00000000000..2281cd3db7d
--- /dev/null
+++ b/src/vnet/tcp/tcp_inlines.h
@@ -0,0 +1,457 @@
+/*
+ * Copyright (c) 2020 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef SRC_VNET_TCP_TCP_INLINES_H_
+#define SRC_VNET_TCP_TCP_INLINES_H_
+
+#include <vnet/tcp/tcp.h>
+
+always_inline tcp_header_t *
+tcp_buffer_hdr (vlib_buffer_t * b)
+{
+  ASSERT ((signed) b->current_data >= (signed) -VLIB_BUFFER_PRE_DATA_SIZE);
+  return (tcp_header_t *) (b->data + b->current_data
+			   + vnet_buffer (b)->tcp.hdr_offset);
+}
+
+always_inline tcp_connection_t *
+tcp_connection_get (u32 conn_index, u32 thread_index)
+{
+  tcp_worker_ctx_t *wrk = tcp_get_worker (thread_index);
+  if (PREDICT_FALSE (pool_is_free_index (wrk->connections, conn_index)))
+    return 0;
+  return pool_elt_at_index (wrk->connections, conn_index);
+}
+
+always_inline tcp_connection_t *
+tcp_connection_get_if_valid (u32 conn_index, u32 thread_index)
+{
+  tcp_worker_ctx_t *wrk;
+  if (thread_index >= vec_len (tcp_main.wrk_ctx))
+    return 0;
+  wrk = tcp_get_worker (thread_index);
+  if (pool_is_free_index (wrk->connections, conn_index))
+    return 0;
+  return pool_elt_at_index (wrk->connections, conn_index);
+}
+
+always_inline void
+tcp_connection_set_state (tcp_connection_t * tc, tcp_state_t state)
+{
+  tc->state = state;
+  TCP_EVT (TCP_EVT_STATE_CHANGE, tc);
+}
+
+always_inline tcp_connection_t *
+tcp_listener_get (u32 tli)
+{
+  tcp_connection_t *tc = 0;
+  if (!pool_is_free_index (tcp_main.listener_pool, tli))
+    tc = pool_elt_at_index (tcp_main.listener_pool, tli);
+  return tc;
+}
+
+always_inline tcp_connection_t *
+tcp_half_open_connection_get (u32 conn_index)
+{
+  tcp_connection_t *tc = 0;
+  clib_spinlock_lock_if_init (&tcp_main.half_open_lock);
+  if (!pool_is_free_index (tcp_main.half_open_connections, conn_index))
+    tc = pool_elt_at_index (tcp_main.half_open_connections, conn_index);
+  clib_spinlock_unlock_if_init (&tcp_main.half_open_lock);
+  return tc;
+}
+
+/**
+ * Our estimate of the number of bytes that have left the network
+ */
+always_inline u32
+tcp_bytes_out (const tcp_connection_t * tc)
+{
+  if (tcp_opts_sack_permitted (&tc->rcv_opts))
+    return tc->sack_sb.sacked_bytes + tc->sack_sb.lost_bytes;
+  else
+    return clib_min (tc->rcv_dupacks * tc->snd_mss,
+		     tc->snd_nxt - tc->snd_una);
+}
+
+/**
+ * Our estimate of the number of bytes in flight (pipe size)
+ */
+always_inline u32
+tcp_flight_size (const tcp_connection_t * tc)
+{
+  int flight_size;
+
+  flight_size = (int) (tc->snd_nxt - tc->snd_una) - tcp_bytes_out (tc)
+    + tc->snd_rxt_bytes - tc->rxt_delivered;
+
+  ASSERT (flight_size >= 0);
+
+  return flight_size;
+}
+
+/**
+ * Initial cwnd as per RFC5681
+ */
+always_inline u32
+tcp_initial_cwnd (const tcp_connection_t * tc)
+{
+  if (tcp_cfg.initial_cwnd_multiplier > 0)
+    return tcp_cfg.initial_cwnd_multiplier * tc->snd_mss;
+
+  if (tc->snd_mss > 2190)
+    return 2 * tc->snd_mss;
+  else if (tc->snd_mss > 1095)
+    return 3 * tc->snd_mss;
+  else
+    return 4 * tc->snd_mss;
+}
+
+/*
+ * Accumulate acked bytes for cwnd increase
+ *
+ * Once threshold bytes are accumulated, snd_mss bytes are added
+ * to the cwnd.
+ */
+always_inline void
+tcp_cwnd_accumulate (tcp_connection_t * tc, u32 thresh, u32 bytes)
+{
+  tc->cwnd_acc_bytes += bytes;
+  if (tc->cwnd_acc_bytes >= thresh)
+    {
+      u32 inc = tc->cwnd_acc_bytes / thresh;
+      tc->cwnd_acc_bytes -= inc * thresh;
+      tc->cwnd += inc * tc->snd_mss;
+      tc->cwnd = clib_min (tc->cwnd, tc->tx_fifo_size);
+    }
+}
+
+always_inline u32
+tcp_loss_wnd (const tcp_connection_t * tc)
+{
+  /* Whatever we have in flight + the packet we're about to send */
+  return tcp_flight_size (tc) + tc->snd_mss;
+}
+
+always_inline u32
+tcp_available_snd_wnd (const tcp_connection_t * tc)
+{
+  return clib_min (tc->cwnd, tc->snd_wnd);
+}
+
+always_inline u32
+tcp_available_output_snd_space (const tcp_connection_t * tc)
+{
+  u32 available_wnd = tcp_available_snd_wnd (tc);
+  int flight_size = (int) (tc->snd_nxt - tc->snd_una);
+
+  if (available_wnd <= flight_size)
+    return 0;
+
+  return available_wnd - flight_size;
+}
+
+/**
+ * Estimate of how many bytes we can still push into the network
+ */
+always_inline u32
+tcp_available_cc_snd_space (const tcp_connection_t * tc)
+{
+  u32 available_wnd = tcp_available_snd_wnd (tc);
+  u32 flight_size = tcp_flight_size (tc);
+
+  if (available_wnd <= flight_size)
+    return 0;
+
+  return available_wnd - flight_size;
+}
+
+always_inline u8
+tcp_is_lost_fin (tcp_connection_t * tc)
+{
+  if ((tc->flags & TCP_CONN_FINSNT) && (tc->snd_una_max - tc->snd_una == 1))
+    return 1;
+  return 0;
+}
+
+always_inline u32
+tcp_time_now (void)
+{
+  return tcp_main.wrk_ctx[vlib_get_thread_index ()].time_now;
+}
+
+always_inline u32
+tcp_time_now_w_thread (u32 thread_index)
+{
+  return tcp_main.wrk_ctx[thread_index].time_now;
+}
+
+/**
+ * Generate timestamp for tcp connection
+ */
+always_inline u32
+tcp_tstamp (tcp_connection_t * tc)
+{
+  return (tcp_main.wrk_ctx[tc->c_thread_index].time_now -
+	  tc->timestamp_delta);
+}
+
+always_inline f64
+tcp_time_now_us (u32 thread_index)
+{
+  return transport_time_now (thread_index);
+}
+
+always_inline u32
+tcp_set_time_now (tcp_worker_ctx_t * wrk)
+{
+  wrk->time_now = clib_cpu_time_now () * tcp_main.tstamp_ticks_per_clock;
+  return wrk->time_now;
+}
+
+always_inline tcp_connection_t *
+tcp_input_lookup_buffer (vlib_buffer_t * b, u8 thread_index, u32 * error,
+			 u8 is_ip4, u8 is_nolookup)
+{
+  u32 fib_index = vnet_buffer (b)->ip.fib_index;
+  int n_advance_bytes, n_data_bytes;
+  transport_connection_t *tc;
+  tcp_header_t *tcp;
+  u8 result = 0;
+
+  if (is_ip4)
+    {
+      ip4_header_t *ip4 = vlib_buffer_get_current (b);
+      int ip_hdr_bytes = ip4_header_bytes (ip4);
+      if (PREDICT_FALSE (b->current_length < ip_hdr_bytes + sizeof (*tcp)))
+	{
+	  *error = TCP_ERROR_LENGTH;
+	  return 0;
+	}
+      tcp = ip4_next_header (ip4);
+      vnet_buffer (b)->tcp.hdr_offset = (u8 *) tcp - (u8 *) ip4;
+      n_advance_bytes = (ip_hdr_bytes + tcp_header_bytes (tcp));
+      n_data_bytes = clib_net_to_host_u16 (ip4->length) - n_advance_bytes;
+
+      /* Length check. Checksum computed by ipx_local no need to compute again */
+      if (PREDICT_FALSE (n_data_bytes < 0))
+	{
+	  *error = TCP_ERROR_LENGTH;
+	  return 0;
+	}
+
+      if (!is_nolookup)
+	tc = session_lookup_connection_wt4 (fib_index, &ip4->dst_address,
+					    &ip4->src_address, tcp->dst_port,
+					    tcp->src_port,
+					    TRANSPORT_PROTO_TCP, thread_index,
+					    &result);
+    }
+  else
+    {
+      ip6_header_t *ip6 = vlib_buffer_get_current (b);
+      if (PREDICT_FALSE (b->current_length < sizeof (*ip6) + sizeof (*tcp)))
+	{
+	  *error = TCP_ERROR_LENGTH;
+	  return 0;
+	}
+      tcp = ip6_next_header (ip6);
+      vnet_buffer (b)->tcp.hdr_offset = (u8 *) tcp - (u8 *) ip6;
+      n_advance_bytes = tcp_header_bytes (tcp);
+      n_data_bytes = clib_net_to_host_u16 (ip6->payload_length)
+	- n_advance_bytes;
+      n_advance_bytes += sizeof (ip6[0]);
+
+      if (PREDICT_FALSE (n_data_bytes < 0))
+	{
+	  *error = TCP_ERROR_LENGTH;
+	  return 0;
+	}
+
+      if (!is_nolookup)
+	{
+	  if (PREDICT_FALSE
+	      (ip6_address_is_link_local_unicast (&ip6->dst_address)))
+	    {
+	      ip4_main_t *im = &ip4_main;
+	      fib_index = vec_elt (im->fib_index_by_sw_if_index,
+				   vnet_buffer (b)->sw_if_index[VLIB_RX]);
+	    }
+
+	  tc = session_lookup_connection_wt6 (fib_index, &ip6->dst_address,
+					      &ip6->src_address,
+					      tcp->dst_port, tcp->src_port,
+					      TRANSPORT_PROTO_TCP,
+					      thread_index, &result);
+	}
+    }
+
+  if (is_nolookup)
+    tc =
+      (transport_connection_t *) tcp_connection_get (vnet_buffer (b)->
+						     tcp.connection_index,
+						     thread_index);
+
+  vnet_buffer (b)->tcp.seq_number = clib_net_to_host_u32 (tcp->seq_number);
+  vnet_buffer (b)->tcp.ack_number = clib_net_to_host_u32 (tcp->ack_number);
+  vnet_buffer (b)->tcp.data_offset = n_advance_bytes;
+  vnet_buffer (b)->tcp.data_len = n_data_bytes;
+  vnet_buffer (b)->tcp.seq_end = vnet_buffer (b)->tcp.seq_number
+    + n_data_bytes;
+  vnet_buffer (b)->tcp.flags = 0;
+
+  *error = result ? TCP_ERROR_NONE + result : *error;
+
+  return tcp_get_connection_from_transport (tc);
+}
+
+/**
+ * Initialize connection by gleaning network and rcv params from buffer
+ *
+ * @param tc		connection to initialize
+ * @param b		buffer whose current data is pointing at ip
+ * @param is_ip4	flag set to 1 if using ip4
+ */
+always_inline void
+tcp_init_w_buffer (tcp_connection_t * tc, vlib_buffer_t * b, u8 is_ip4)
+{
+  tcp_header_t *th = tcp_buffer_hdr (b);
+
+  tc->c_lcl_port = th->dst_port;
+  tc->c_rmt_port = th->src_port;
+  tc->c_is_ip4 = is_ip4;
+
+  if (is_ip4)
+    {
+      ip4_header_t *ip4 = vlib_buffer_get_current (b);
+      tc->c_lcl_ip4.as_u32 = ip4->dst_address.as_u32;
+      tc->c_rmt_ip4.as_u32 = ip4->src_address.as_u32;
+    }
+  else
+    {
+      ip6_header_t *ip6 = vlib_buffer_get_current (b);
+      clib_memcpy_fast (&tc->c_lcl_ip6, &ip6->dst_address,
+			sizeof (ip6_address_t));
+      clib_memcpy_fast (&tc->c_rmt_ip6, &ip6->src_address,
+			sizeof (ip6_address_t));
+    }
+
+  tc->irs = vnet_buffer (b)->tcp.seq_number;
+  tc->rcv_nxt = vnet_buffer (b)->tcp.seq_number + 1;
+  tc->rcv_las = tc->rcv_nxt;
+  tc->sw_if_index = vnet_buffer (b)->sw_if_index[VLIB_RX];
+  tc->snd_wl1 = vnet_buffer (b)->tcp.seq_number;
+  tc->snd_wl2 = vnet_buffer (b)->tcp.ack_number;
+
+  /* RFC1323: TSval timestamps sent on {SYN} and {SYN,ACK}
+   * segments are used to initialize PAWS. */
+  if (tcp_opts_tstamp (&tc->rcv_opts))
+    {
+      tc->tsval_recent = tc->rcv_opts.tsval;
+      tc->tsval_recent_age = tcp_time_now ();
+    }
+
+  if (tcp_opts_wscale (&tc->rcv_opts))
+    tc->snd_wscale = tc->rcv_opts.wscale;
+
+  tc->snd_wnd = clib_net_to_host_u16 (th->window) << tc->snd_wscale;
+}
+
+always_inline void
+tcp_update_rto (tcp_connection_t * tc)
+{
+  tc->rto = clib_min (tc->srtt + (tc->rttvar << 2), TCP_RTO_MAX);
+  tc->rto = clib_max (tc->rto, TCP_RTO_MIN);
+}
+
+always_inline u8
+tcp_is_descheduled (tcp_connection_t * tc)
+{
+  return (transport_connection_is_descheduled (&tc->connection) ? 1 : 0);
+}
+
+/**
+ * Push TCP header to buffer
+ *
+ * @param vm - vlib_main
+ * @param b - buffer to write the header to
+ * @param sp_net - source port net order
+ * @param dp_net - destination port net order
+ * @param seq - sequence number net order
+ * @param ack - ack number net order
+ * @param tcp_hdr_opts_len - header and options length in bytes
+ * @param flags - header flags
+ * @param wnd - window size
+ *
+ * @return - pointer to start of TCP header
+ */
+always_inline void *
+vlib_buffer_push_tcp_net_order (vlib_buffer_t * b, u16 sp, u16 dp, u32 seq,
+				u32 ack, u8 tcp_hdr_opts_len, u8 flags,
+				u16 wnd)
+{
+  tcp_header_t *th;
+
+  th = vlib_buffer_push_uninit (b, tcp_hdr_opts_len);
+
+  th->src_port = sp;
+  th->dst_port = dp;
+  th->seq_number = seq;
+  th->ack_number = ack;
+  th->data_offset_and_reserved = (tcp_hdr_opts_len >> 2) << 4;
+  th->flags = flags;
+  th->window = wnd;
+  th->checksum = 0;
+  th->urgent_pointer = 0;
+  vnet_buffer (b)->l4_hdr_offset = (u8 *) th - b->data;
+  b->flags |= VNET_BUFFER_F_L4_HDR_OFFSET_VALID;
+  return th;
+}
+
+/**
+ * Push TCP header to buffer
+ *
+ * @param b - buffer to write the header to
+ * @param sp_net - source port net order
+ * @param dp_net - destination port net order
+ * @param seq - sequence number host order
+ * @param ack - ack number host order
+ * @param tcp_hdr_opts_len - header and options length in bytes
+ * @param flags - header flags
+ * @param wnd - window size
+ *
+ * @return - pointer to start of TCP header
+ */
+always_inline void *
+vlib_buffer_push_tcp (vlib_buffer_t * b, u16 sp_net, u16 dp_net, u32 seq,
+		      u32 ack, u8 tcp_hdr_opts_len, u8 flags, u16 wnd)
+{
+  return vlib_buffer_push_tcp_net_order (b, sp_net, dp_net,
+					 clib_host_to_net_u32 (seq),
+					 clib_host_to_net_u32 (ack),
+					 tcp_hdr_opts_len, flags,
+					 clib_host_to_net_u16 (wnd));
+}
+
+#endif /* SRC_VNET_TCP_TCP_INLINES_H_ */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/vnet/tcp/tcp_input.c b/src/vnet/tcp/tcp_input.c
index 86158b9d6c6..e27cffb9444 100755
--- a/src/vnet/tcp/tcp_input.c
+++ b/src/vnet/tcp/tcp_input.c
@@ -16,8 +16,8 @@
 #include <vppinfra/sparse_vec.h>
 #include <vnet/fib/ip4_fib.h>
 #include <vnet/fib/ip6_fib.h>
-#include <vnet/tcp/tcp_packet.h>
 #include <vnet/tcp/tcp.h>
+#include <vnet/tcp/tcp_inlines.h>
 #include <vnet/session/session.h>
 #include <math.h>
 
@@ -116,119 +116,6 @@ tcp_segment_in_rcv_wnd (tcp_connection_t * tc, u32 seq, u32 end_seq)
 }
 
 /**
- * Parse TCP header options.
- *
- * @param th TCP header
- * @param to TCP options data structure to be populated
- * @param is_syn set if packet is syn
- * @return -1 if parsing failed
- */
-static inline int
-tcp_options_parse (tcp_header_t * th, tcp_options_t * to, u8 is_syn)
-{
-  const u8 *data;
-  u8 opt_len, opts_len, kind;
-  int j;
-  sack_block_t b;
-
-  opts_len = (tcp_doff (th) << 2) - sizeof (tcp_header_t);
-  data = (const u8 *) (th + 1);
-
-  /* Zero out all flags but those set in SYN */
-  to->flags &= (TCP_OPTS_FLAG_SACK_PERMITTED | TCP_OPTS_FLAG_WSCALE
-		| TCP_OPTS_FLAG_TSTAMP | TCP_OPTS_FLAG_MSS);
-
-  for (; opts_len > 0; opts_len -= opt_len, data += opt_len)
-    {
-      kind = data[0];
-
-      /* Get options length */
-      if (kind == TCP_OPTION_EOL)
-	break;
-      else if (kind == TCP_OPTION_NOOP)
-	{
-	  opt_len = 1;
-	  continue;
-	}
-      else
-	{
-	  /* broken options */
-	  if (opts_len < 2)
-	    return -1;
-	  opt_len = data[1];
-
-	  /* weird option length */
-	  if (opt_len < 2 || opt_len > opts_len)
-	    return -1;
-	}
-
-      /* Parse options */
-      switch (kind)
-	{
-	case TCP_OPTION_MSS:
-	  if (!is_syn)
-	    break;
-	  if ((opt_len == TCP_OPTION_LEN_MSS) && tcp_syn (th))
-	    {
-	      to->flags |= TCP_OPTS_FLAG_MSS;
-	      to->mss = clib_net_to_host_u16 (*(u16 *) (data + 2));
-	    }
-	  break;
-	case TCP_OPTION_WINDOW_SCALE:
-	  if (!is_syn)
-	    break;
-	  if ((opt_len == TCP_OPTION_LEN_WINDOW_SCALE) && tcp_syn (th))
-	    {
-	      to->flags |= TCP_OPTS_FLAG_WSCALE;
-	      to->wscale = data[2];
-	      if (to->wscale > TCP_MAX_WND_SCALE)
-		to->wscale = TCP_MAX_WND_SCALE;
-	    }
-	  break;
-	case TCP_OPTION_TIMESTAMP:
-	  if (is_syn)
-	    to->flags |= TCP_OPTS_FLAG_TSTAMP;
-	  if ((to->flags & TCP_OPTS_FLAG_TSTAMP)
-	      && opt_len == TCP_OPTION_LEN_TIMESTAMP)
-	    {
-	      to->tsval = clib_net_to_host_u32 (*(u32 *) (data + 2));
-	      to->tsecr = clib_net_to_host_u32 (*(u32 *) (data + 6));
-	    }
-	  break;
-	case TCP_OPTION_SACK_PERMITTED:
-	  if (!is_syn)
-	    break;
-	  if (opt_len == TCP_OPTION_LEN_SACK_PERMITTED && tcp_syn (th))
-	    to->flags |= TCP_OPTS_FLAG_SACK_PERMITTED;
-	  break;
-	case TCP_OPTION_SACK_BLOCK:
-	  /* If SACK permitted was not advertised or a SYN, break */
-	  if ((to->flags & TCP_OPTS_FLAG_SACK_PERMITTED) == 0 || tcp_syn (th))
-	    break;
-
-	  /* If too short or not correctly formatted, break */
-	  if (opt_len < 10 || ((opt_len - 2) % TCP_OPTION_LEN_SACK_BLOCK))
-	    break;
-
-	  to->flags |= TCP_OPTS_FLAG_SACK;
-	  to->n_sack_blocks = (opt_len - 2) / TCP_OPTION_LEN_SACK_BLOCK;
-	  vec_reset_length (to->sacks);
-	  for (j = 0; j < to->n_sack_blocks; j++)
-	    {
-	      b.start = clib_net_to_host_u32 (*(u32 *) (data + 2 + 8 * j));
-	      b.end = clib_net_to_host_u32 (*(u32 *) (data + 6 + 8 * j));
-	      vec_add1 (to->sacks, b);
-	    }
-	  break;
-	default:
-	  /* Nothing to see here */
-	  continue;
-	}
-    }
-  return 0;
-}
-
-/**
  * RFC1323: Check against wrapped sequence numbers (PAWS). If we have
  * timestamp to echo and it's less than tsval_recent, drop segment
  * but still send an ACK in order to retain TCP's mechanism for detecting
@@ -565,15 +452,6 @@ tcp_estimate_rtt (tcp_connection_t * tc, u32 mrtt)
     }
 }
 
-#ifndef CLIB_MARCH_VARIANT
-void
-tcp_update_rto (tcp_connection_t * tc)
-{
-  tc->rto = clib_min (tc->srtt + (tc->rttvar << 2), TCP_RTO_MAX);
-  tc->rto = clib_max (tc->rto, TCP_RTO_MIN);
-}
-#endif /* CLIB_MARCH_VARIANT */
-
 /**
  * Update RTT estimate and RTO timer
  *
@@ -726,567 +604,6 @@ tcp_program_dequeue (tcp_worker_ctx_t * wrk, tcp_connection_t * tc)
   tc->burst_acked += tc->bytes_acked;
 }
 
-#ifndef CLIB_MARCH_VARIANT
-static u32
-scoreboard_hole_index (sack_scoreboard_t * sb, sack_scoreboard_hole_t * hole)
-{
-  ASSERT (!pool_is_free_index (sb->holes, hole - sb->holes));
-  return hole - sb->holes;
-}
-
-static u32
-scoreboard_hole_bytes (sack_scoreboard_hole_t * hole)
-{
-  return hole->end - hole->start;
-}
-
-sack_scoreboard_hole_t *
-scoreboard_get_hole (sack_scoreboard_t * sb, u32 index)
-{
-  if (index != TCP_INVALID_SACK_HOLE_INDEX)
-    return pool_elt_at_index (sb->holes, index);
-  return 0;
-}
-
-sack_scoreboard_hole_t *
-scoreboard_next_hole (sack_scoreboard_t * sb, sack_scoreboard_hole_t * hole)
-{
-  if (hole->next != TCP_INVALID_SACK_HOLE_INDEX)
-    return pool_elt_at_index (sb->holes, hole->next);
-  return 0;
-}
-
-sack_scoreboard_hole_t *
-scoreboard_prev_hole (sack_scoreboard_t * sb, sack_scoreboard_hole_t * hole)
-{
-  if (hole->prev != TCP_INVALID_SACK_HOLE_INDEX)
-    return pool_elt_at_index (sb->holes, hole->prev);
-  return 0;
-}
-
-sack_scoreboard_hole_t *
-scoreboard_first_hole (sack_scoreboard_t * sb)
-{
-  if (sb->head != TCP_INVALID_SACK_HOLE_INDEX)
-    return pool_elt_at_index (sb->holes, sb->head);
-  return 0;
-}
-
-sack_scoreboard_hole_t *
-scoreboard_last_hole (sack_scoreboard_t * sb)
-{
-  if (sb->tail != TCP_INVALID_SACK_HOLE_INDEX)
-    return pool_elt_at_index (sb->holes, sb->tail);
-  return 0;
-}
-
-static void
-scoreboard_remove_hole (sack_scoreboard_t * sb, sack_scoreboard_hole_t * hole)
-{
-  sack_scoreboard_hole_t *next, *prev;
-
-  if (hole->next != TCP_INVALID_SACK_HOLE_INDEX)
-    {
-      next = pool_elt_at_index (sb->holes, hole->next);
-      next->prev = hole->prev;
-    }
-  else
-    {
-      sb->tail = hole->prev;
-    }
-
-  if (hole->prev != TCP_INVALID_SACK_HOLE_INDEX)
-    {
-      prev = pool_elt_at_index (sb->holes, hole->prev);
-      prev->next = hole->next;
-    }
-  else
-    {
-      sb->head = hole->next;
-    }
-
-  if (scoreboard_hole_index (sb, hole) == sb->cur_rxt_hole)
-    sb->cur_rxt_hole = TCP_INVALID_SACK_HOLE_INDEX;
-
-  /* Poison the entry */
-  if (CLIB_DEBUG > 0)
-    clib_memset (hole, 0xfe, sizeof (*hole));
-
-  pool_put (sb->holes, hole);
-}
-
-static sack_scoreboard_hole_t *
-scoreboard_insert_hole (sack_scoreboard_t * sb, u32 prev_index,
-			u32 start, u32 end)
-{
-  sack_scoreboard_hole_t *hole, *next, *prev;
-  u32 hole_index;
-
-  pool_get (sb->holes, hole);
-  clib_memset (hole, 0, sizeof (*hole));
-
-  hole->start = start;
-  hole->end = end;
-  hole_index = scoreboard_hole_index (sb, hole);
-
-  prev = scoreboard_get_hole (sb, prev_index);
-  if (prev)
-    {
-      hole->prev = prev_index;
-      hole->next = prev->next;
-
-      if ((next = scoreboard_next_hole (sb, hole)))
-	next->prev = hole_index;
-      else
-	sb->tail = hole_index;
-
-      prev->next = hole_index;
-    }
-  else
-    {
-      sb->head = hole_index;
-      hole->prev = TCP_INVALID_SACK_HOLE_INDEX;
-      hole->next = TCP_INVALID_SACK_HOLE_INDEX;
-    }
-
-  return hole;
-}
-
-always_inline void
-scoreboard_update_sacked_rxt (sack_scoreboard_t * sb, u32 start, u32 end,
-			      u8 has_rxt)
-{
-  if (!has_rxt || seq_geq (start, sb->high_rxt))
-    return;
-
-  sb->rxt_sacked +=
-    seq_lt (end, sb->high_rxt) ? (end - start) : (sb->high_rxt - start);
-}
-
-always_inline void
-scoreboard_update_bytes (sack_scoreboard_t * sb, u32 ack, u32 snd_mss)
-{
-  sack_scoreboard_hole_t *left, *right;
-  u32 sacked = 0, blks = 0, old_sacked;
-
-  old_sacked = sb->sacked_bytes;
-
-  sb->last_lost_bytes = 0;
-  sb->lost_bytes = 0;
-  sb->sacked_bytes = 0;
-
-  right = scoreboard_last_hole (sb);
-  if (!right)
-    {
-      sb->sacked_bytes = sb->high_sacked - ack;
-      sb->last_sacked_bytes = sb->sacked_bytes
-	- (old_sacked - sb->last_bytes_delivered);
-      return;
-    }
-
-  if (seq_gt (sb->high_sacked, right->end))
-    {
-      sacked = sb->high_sacked - right->end;
-      blks = 1;
-    }
-
-  while (sacked < (TCP_DUPACK_THRESHOLD - 1) * snd_mss
-	 && blks < TCP_DUPACK_THRESHOLD)
-    {
-      if (right->is_lost)
-	sb->lost_bytes += scoreboard_hole_bytes (right);
-
-      left = scoreboard_prev_hole (sb, right);
-      if (!left)
-	{
-	  ASSERT (right->start == ack || sb->is_reneging);
-	  sacked += right->start - ack;
-	  right = 0;
-	  break;
-	}
-
-      sacked += right->start - left->end;
-      blks++;
-      right = left;
-    }
-
-  /* right is first lost */
-  while (right)
-    {
-      sb->lost_bytes += scoreboard_hole_bytes (right);
-      sb->last_lost_bytes += right->is_lost ? 0 : (right->end - right->start);
-      right->is_lost = 1;
-      left = scoreboard_prev_hole (sb, right);
-      if (!left)
-	{
-	  ASSERT (right->start == ack || sb->is_reneging);
-	  sacked += right->start - ack;
-	  break;
-	}
-      sacked += right->start - left->end;
-      right = left;
-    }
-
-  sb->sacked_bytes = sacked;
-  sb->last_sacked_bytes = sacked - (old_sacked - sb->last_bytes_delivered);
-}
-
-/**
- * Figure out the next hole to retransmit
- *
- * Follows logic proposed in RFC6675 Sec. 4, NextSeg()
- */
-sack_scoreboard_hole_t *
-scoreboard_next_rxt_hole (sack_scoreboard_t * sb,
-			  sack_scoreboard_hole_t * start,
-			  u8 have_unsent, u8 * can_rescue, u8 * snd_limited)
-{
-  sack_scoreboard_hole_t *hole = 0;
-
-  hole = start ? start : scoreboard_first_hole (sb);
-  while (hole && seq_leq (hole->end, sb->high_rxt) && hole->is_lost)
-    hole = scoreboard_next_hole (sb, hole);
-
-  /* Nothing, return */
-  if (!hole)
-    {
-      sb->cur_rxt_hole = TCP_INVALID_SACK_HOLE_INDEX;
-      return 0;
-    }
-
-  /* Rule (1): if higher than rxt, less than high_sacked and lost */
-  if (hole->is_lost && seq_lt (hole->start, sb->high_sacked))
-    {
-      sb->cur_rxt_hole = scoreboard_hole_index (sb, hole);
-    }
-  else
-    {
-      /* Rule (2): available unsent data */
-      if (have_unsent)
-	{
-	  sb->cur_rxt_hole = TCP_INVALID_SACK_HOLE_INDEX;
-	  return 0;
-	}
-      /* Rule (3): if hole not lost */
-      else if (seq_lt (hole->start, sb->high_sacked))
-	{
-	  /* And we didn't already retransmit it */
-	  if (seq_leq (hole->end, sb->high_rxt))
-	    {
-	      sb->cur_rxt_hole = TCP_INVALID_SACK_HOLE_INDEX;
-	      return 0;
-	    }
-	  *snd_limited = 0;
-	  sb->cur_rxt_hole = scoreboard_hole_index (sb, hole);
-	}
-      /* Rule (4): if hole beyond high_sacked */
-      else
-	{
-	  ASSERT (seq_geq (hole->start, sb->high_sacked));
-	  *snd_limited = 1;
-	  *can_rescue = 1;
-	  /* HighRxt MUST NOT be updated */
-	  return 0;
-	}
-    }
-
-  if (hole && seq_lt (sb->high_rxt, hole->start))
-    sb->high_rxt = hole->start;
-
-  return hole;
-}
-
-void
-scoreboard_init_rxt (sack_scoreboard_t * sb, u32 snd_una)
-{
-  sack_scoreboard_hole_t *hole;
-  hole = scoreboard_first_hole (sb);
-  if (hole)
-    {
-      snd_una = seq_gt (snd_una, hole->start) ? snd_una : hole->start;
-      sb->cur_rxt_hole = sb->head;
-    }
-  sb->high_rxt = snd_una;
-  sb->rescue_rxt = snd_una - 1;
-}
-
-void
-scoreboard_init (sack_scoreboard_t * sb)
-{
-  sb->head = TCP_INVALID_SACK_HOLE_INDEX;
-  sb->tail = TCP_INVALID_SACK_HOLE_INDEX;
-  sb->cur_rxt_hole = TCP_INVALID_SACK_HOLE_INDEX;
-}
-
-void
-scoreboard_clear (sack_scoreboard_t * sb)
-{
-  sack_scoreboard_hole_t *hole;
-  while ((hole = scoreboard_first_hole (sb)))
-    {
-      scoreboard_remove_hole (sb, hole);
-    }
-  ASSERT (sb->head == sb->tail && sb->head == TCP_INVALID_SACK_HOLE_INDEX);
-  ASSERT (pool_elts (sb->holes) == 0);
-  sb->sacked_bytes = 0;
-  sb->last_sacked_bytes = 0;
-  sb->last_bytes_delivered = 0;
-  sb->lost_bytes = 0;
-  sb->last_lost_bytes = 0;
-  sb->cur_rxt_hole = TCP_INVALID_SACK_HOLE_INDEX;
-  sb->is_reneging = 0;
-}
-
-void
-scoreboard_clear_reneging (sack_scoreboard_t * sb, u32 start, u32 end)
-{
-  sack_scoreboard_hole_t *last_hole;
-
-  clib_warning ("sack reneging");
-
-  scoreboard_clear (sb);
-  last_hole = scoreboard_insert_hole (sb, TCP_INVALID_SACK_HOLE_INDEX,
-				      start, end);
-  last_hole->is_lost = 1;
-  sb->tail = scoreboard_hole_index (sb, last_hole);
-  sb->high_sacked = start;
-  scoreboard_init_rxt (sb, start);
-}
-
-#endif /* CLIB_MARCH_VARIANT */
-
-/**
- * Test that scoreboard is sane after recovery
- *
- * Returns 1 if scoreboard is empty or if first hole beyond
- * snd_una.
- */
-static u8
-tcp_scoreboard_is_sane_post_recovery (tcp_connection_t * tc)
-{
-  sack_scoreboard_hole_t *hole;
-  hole = scoreboard_first_hole (&tc->sack_sb);
-  return (!hole || (seq_geq (hole->start, tc->snd_una)
-		    && seq_lt (hole->end, tc->snd_nxt)));
-}
-
-#ifndef CLIB_MARCH_VARIANT
-
-void
-tcp_rcv_sacks (tcp_connection_t * tc, u32 ack)
-{
-  sack_scoreboard_hole_t *hole, *next_hole;
-  sack_scoreboard_t *sb = &tc->sack_sb;
-  sack_block_t *blk, *rcv_sacks;
-  u32 blk_index = 0, i, j;
-  u8 has_rxt;
-
-  sb->last_sacked_bytes = 0;
-  sb->last_bytes_delivered = 0;
-  sb->rxt_sacked = 0;
-
-  if (!tcp_opts_sack (&tc->rcv_opts) && !sb->sacked_bytes
-      && sb->head == TCP_INVALID_SACK_HOLE_INDEX)
-    return;
-
-  has_rxt = tcp_in_cong_recovery (tc);
-
-  /* Remove invalid blocks */
-  blk = tc->rcv_opts.sacks;
-  while (blk < vec_end (tc->rcv_opts.sacks))
-    {
-      if (seq_lt (blk->start, blk->end)
-	  && seq_gt (blk->start, tc->snd_una)
-	  && seq_gt (blk->start, ack) && seq_leq (blk->end, tc->snd_nxt))
-	{
-	  blk++;
-	  continue;
-	}
-      vec_del1 (tc->rcv_opts.sacks, blk - tc->rcv_opts.sacks);
-    }
-
-  /* Add block for cumulative ack */
-  if (seq_gt (ack, tc->snd_una))
-    {
-      vec_add2 (tc->rcv_opts.sacks, blk, 1);
-      blk->start = tc->snd_una;
-      blk->end = ack;
-    }
-
-  if (vec_len (tc->rcv_opts.sacks) == 0)
-    return;
-
-  tcp_scoreboard_trace_add (tc, ack);
-
-  /* Make sure blocks are ordered */
-  rcv_sacks = tc->rcv_opts.sacks;
-  for (i = 0; i < vec_len (rcv_sacks); i++)
-    for (j = i + 1; j < vec_len (rcv_sacks); j++)
-      if (seq_lt (rcv_sacks[j].start, rcv_sacks[i].start))
-	{
-	  sack_block_t tmp = rcv_sacks[i];
-	  rcv_sacks[i] = rcv_sacks[j];
-	  rcv_sacks[j] = tmp;
-	}
-
-  if (sb->head == TCP_INVALID_SACK_HOLE_INDEX)
-    {
-      /* Handle reneging as a special case */
-      if (PREDICT_FALSE (sb->is_reneging))
-	{
-	  /* No holes, only sacked bytes */
-	  if (seq_leq (tc->snd_nxt, sb->high_sacked))
-	    {
-	      /* No progress made so return */
-	      if (seq_leq (ack, tc->snd_una))
-		return;
-
-	      /* Update sacked bytes delivered and return */
-	      sb->last_bytes_delivered = ack - tc->snd_una;
-	      sb->sacked_bytes -= sb->last_bytes_delivered;
-	      sb->is_reneging = seq_lt (ack, sb->high_sacked);
-	      return;
-	    }
-
-	  /* New hole above high sacked. Add it and process normally */
-	  hole = scoreboard_insert_hole (sb, TCP_INVALID_SACK_HOLE_INDEX,
-					 sb->high_sacked, tc->snd_nxt);
-	  sb->tail = scoreboard_hole_index (sb, hole);
-	}
-      /* Not reneging and no holes. Insert the first that covers all
-       * outstanding bytes */
-      else
-	{
-	  hole = scoreboard_insert_hole (sb, TCP_INVALID_SACK_HOLE_INDEX,
-					 tc->snd_una, tc->snd_nxt);
-	  sb->tail = scoreboard_hole_index (sb, hole);
-	}
-      sb->high_sacked = rcv_sacks[vec_len (rcv_sacks) - 1].end;
-    }
-  else
-    {
-      /* If we have holes but snd_nxt is beyond the last hole, update
-       * last hole end or add new hole after high sacked */
-      hole = scoreboard_last_hole (sb);
-      if (seq_gt (tc->snd_nxt, hole->end))
-	{
-	  if (seq_geq (hole->start, sb->high_sacked))
-	    {
-	      hole->end = tc->snd_nxt;
-	    }
-	  /* New hole after high sacked block */
-	  else if (seq_lt (sb->high_sacked, tc->snd_nxt))
-	    {
-	      scoreboard_insert_hole (sb, sb->tail, sb->high_sacked,
-				      tc->snd_nxt);
-	    }
-	}
-
-      /* Keep track of max byte sacked for when the last hole
-       * is acked */
-      sb->high_sacked = seq_max (rcv_sacks[vec_len (rcv_sacks) - 1].end,
-				 sb->high_sacked);
-    }
-
-  /* Walk the holes with the SACK blocks */
-  hole = pool_elt_at_index (sb->holes, sb->head);
-
-  if (PREDICT_FALSE (sb->is_reneging))
-    {
-      sb->last_bytes_delivered += clib_min (hole->start - tc->snd_una,
-					    ack - tc->snd_una);
-      sb->is_reneging = seq_lt (ack, hole->start);
-    }
-
-  while (hole && blk_index < vec_len (rcv_sacks))
-    {
-      blk = &rcv_sacks[blk_index];
-      if (seq_leq (blk->start, hole->start))
-	{
-	  /* Block covers hole. Remove hole */
-	  if (seq_geq (blk->end, hole->end))
-	    {
-	      next_hole = scoreboard_next_hole (sb, hole);
-
-	      /* If covered by ack, compute delivered bytes */
-	      if (blk->end == ack)
-		{
-		  u32 sacked = next_hole ? next_hole->start : sb->high_sacked;
-		  if (PREDICT_FALSE (seq_lt (ack, sacked)))
-		    {
-		      sb->last_bytes_delivered += ack - hole->end;
-		      sb->is_reneging = 1;
-		    }
-		  else
-		    {
-		      sb->last_bytes_delivered += sacked - hole->end;
-		      sb->is_reneging = 0;
-		    }
-		}
-	      scoreboard_update_sacked_rxt (sb, hole->start, hole->end,
-					    has_rxt);
-	      scoreboard_remove_hole (sb, hole);
-	      hole = next_hole;
-	    }
-	  /* Partial 'head' overlap */
-	  else
-	    {
-	      if (seq_gt (blk->end, hole->start))
-		{
-		  scoreboard_update_sacked_rxt (sb, hole->start, blk->end,
-						has_rxt);
-		  hole->start = blk->end;
-		}
-	      blk_index++;
-	    }
-	}
-      else
-	{
-	  /* Hole must be split */
-	  if (seq_lt (blk->end, hole->end))
-	    {
-	      u32 hole_index = scoreboard_hole_index (sb, hole);
-	      next_hole = scoreboard_insert_hole (sb, hole_index, blk->end,
-						  hole->end);
-	      /* Pool might've moved */
-	      hole = scoreboard_get_hole (sb, hole_index);
-	      hole->end = blk->start;
-
-	      scoreboard_update_sacked_rxt (sb, blk->start, blk->end,
-					    has_rxt);
-
-	      blk_index++;
-	      ASSERT (hole->next == scoreboard_hole_index (sb, next_hole));
-	    }
-	  else if (seq_lt (blk->start, hole->end))
-	    {
-	      scoreboard_update_sacked_rxt (sb, blk->start, hole->end,
-					    has_rxt);
-	      hole->end = blk->start;
-	    }
-	  hole = scoreboard_next_hole (sb, hole);
-	}
-    }
-
-  scoreboard_update_bytes (sb, ack, tc->snd_mss);
-
-  ASSERT (sb->last_sacked_bytes <= sb->sacked_bytes || tcp_in_recovery (tc));
-  ASSERT (sb->sacked_bytes == 0 || tcp_in_recovery (tc)
-	  || sb->sacked_bytes <= tc->snd_nxt - seq_max (tc->snd_una, ack));
-  ASSERT (sb->last_sacked_bytes + sb->lost_bytes <= tc->snd_nxt
-	  - seq_max (tc->snd_una, ack) || tcp_in_recovery (tc));
-  ASSERT (sb->head == TCP_INVALID_SACK_HOLE_INDEX || tcp_in_recovery (tc)
-	  || sb->is_reneging || sb->holes[sb->head].start == ack);
-  ASSERT (sb->last_lost_bytes <= sb->lost_bytes);
-  ASSERT ((ack - tc->snd_una) + sb->last_sacked_bytes
-	  - sb->last_bytes_delivered >= sb->rxt_sacked);
-  ASSERT ((ack - tc->snd_una) >= tc->sack_sb.last_bytes_delivered
-	  || (tc->flags & TCP_CONN_FINSNT));
-
-  TCP_EVT (TCP_EVT_CC_SCOREBOARD, tc);
-}
-#endif /* CLIB_MARCH_VARIANT */
-
 /**
  * Try to update snd_wnd based on feedback received from peer.
  *
@@ -1825,89 +1142,6 @@ tcp_rcv_fin (tcp_worker_ctx_t * wrk, tcp_connection_t * tc, vlib_buffer_t * b,
   *error = TCP_ERROR_FIN_RCVD;
 }
 
-#ifndef CLIB_MARCH_VARIANT
-static u8
-tcp_sack_vector_is_sane (sack_block_t * sacks)
-{
-  int i;
-  for (i = 1; i < vec_len (sacks); i++)
-    {
-      if (sacks[i - 1].end == sacks[i].start)
-	return 0;
-    }
-  return 1;
-}
-
-/**
- * Build SACK list as per RFC2018.
- *
- * Makes sure the first block contains the segment that generated the current
- * ACK and the following ones are the ones most recently reported in SACK
- * blocks.
- *
- * @param tc TCP connection for which the SACK list is updated
- * @param start Start sequence number of the newest SACK block
- * @param end End sequence of the newest SACK block
- */
-void
-tcp_update_sack_list (tcp_connection_t * tc, u32 start, u32 end)
-{
-  sack_block_t *new_list = tc->snd_sacks_fl, *block = 0;
-  int i;
-
-  /* If the first segment is ooo add it to the list. Last write might've moved
-   * rcv_nxt over the first segment. */
-  if (seq_lt (tc->rcv_nxt, start))
-    {
-      vec_add2 (new_list, block, 1);
-      block->start = start;
-      block->end = end;
-    }
-
-  /* Find the blocks still worth keeping. */
-  for (i = 0; i < vec_len (tc->snd_sacks); i++)
-    {
-      /* Discard if rcv_nxt advanced beyond current block */
-      if (seq_leq (tc->snd_sacks[i].start, tc->rcv_nxt))
-	continue;
-
-      /* Merge or drop if segment overlapped by the new segment */
-      if (block && (seq_geq (tc->snd_sacks[i].end, new_list[0].start)
-		    && seq_leq (tc->snd_sacks[i].start, new_list[0].end)))
-	{
-	  if (seq_lt (tc->snd_sacks[i].start, new_list[0].start))
-	    new_list[0].start = tc->snd_sacks[i].start;
-	  if (seq_lt (new_list[0].end, tc->snd_sacks[i].end))
-	    new_list[0].end = tc->snd_sacks[i].end;
-	  continue;
-	}
-
-      /* Save to new SACK list if we have space. */
-      if (vec_len (new_list) < TCP_MAX_SACK_BLOCKS)
-	vec_add1 (new_list, tc->snd_sacks[i]);
-    }
-
-  ASSERT (vec_len (new_list) <= TCP_MAX_SACK_BLOCKS);
-
-  /* Replace old vector with new one */
-  vec_reset_length (tc->snd_sacks);
-  tc->snd_sacks_fl = tc->snd_sacks;
-  tc->snd_sacks = new_list;
-
-  /* Segments should not 'touch' */
-  ASSERT (tcp_sack_vector_is_sane (tc->snd_sacks));
-}
-
-u32
-tcp_sack_list_bytes (tcp_connection_t * tc)
-{
-  u32 bytes = 0, i;
-  for (i = 0; i < vec_len (tc->snd_sacks); i++)
-    bytes += tc->snd_sacks[i].end - tc->snd_sacks[i].start;
-  return bytes;
-}
-#endif /* CLIB_MARCH_VARIANT */
-
 /** Enqueue data for delivery to application */
 static int
 tcp_session_enqueue_data (tcp_connection_t * tc, vlib_buffer_t * b,
@@ -3551,102 +2785,6 @@ tcp_input_set_error_next (tcp_main_t * tm, u16 * next, u32 * error, u8 is_ip4)
     }
 }
 
-always_inline tcp_connection_t *
-tcp_input_lookup_buffer (vlib_buffer_t * b, u8 thread_index, u32 * error,
-			 u8 is_ip4, u8 is_nolookup)
-{
-  u32 fib_index = vnet_buffer (b)->ip.fib_index;
-  int n_advance_bytes, n_data_bytes;
-  transport_connection_t *tc;
-  tcp_header_t *tcp;
-  u8 result = 0;
-
-  if (is_ip4)
-    {
-      ip4_header_t *ip4 = vlib_buffer_get_current (b);
-      int ip_hdr_bytes = ip4_header_bytes (ip4);
-      if (PREDICT_FALSE (b->current_length < ip_hdr_bytes + sizeof (*tcp)))
-	{
-	  *error = TCP_ERROR_LENGTH;
-	  return 0;
-	}
-      tcp = ip4_next_header (ip4);
-      vnet_buffer (b)->tcp.hdr_offset = (u8 *) tcp - (u8 *) ip4;
-      n_advance_bytes = (ip_hdr_bytes + tcp_header_bytes (tcp));
-      n_data_bytes = clib_net_to_host_u16 (ip4->length) - n_advance_bytes;
-
-      /* Length check. Checksum computed by ipx_local no need to compute again */
-      if (PREDICT_FALSE (n_data_bytes < 0))
-	{
-	  *error = TCP_ERROR_LENGTH;
-	  return 0;
-	}
-
-      if (!is_nolookup)
-	tc = session_lookup_connection_wt4 (fib_index, &ip4->dst_address,
-					    &ip4->src_address, tcp->dst_port,
-					    tcp->src_port,
-					    TRANSPORT_PROTO_TCP, thread_index,
-					    &result);
-    }
-  else
-    {
-      ip6_header_t *ip6 = vlib_buffer_get_current (b);
-      if (PREDICT_FALSE (b->current_length < sizeof (*ip6) + sizeof (*tcp)))
-	{
-	  *error = TCP_ERROR_LENGTH;
-	  return 0;
-	}
-      tcp = ip6_next_header (ip6);
-      vnet_buffer (b)->tcp.hdr_offset = (u8 *) tcp - (u8 *) ip6;
-      n_advance_bytes = tcp_header_bytes (tcp);
-      n_data_bytes = clib_net_to_host_u16 (ip6->payload_length)
-	- n_advance_bytes;
-      n_advance_bytes += sizeof (ip6[0]);
-
-      if (PREDICT_FALSE (n_data_bytes < 0))
-	{
-	  *error = TCP_ERROR_LENGTH;
-	  return 0;
-	}
-
-      if (!is_nolookup)
-	{
-	  if (PREDICT_FALSE
-	      (ip6_address_is_link_local_unicast (&ip6->dst_address)))
-	    {
-	      ip4_main_t *im = &ip4_main;
-	      fib_index = vec_elt (im->fib_index_by_sw_if_index,
-				   vnet_buffer (b)->sw_if_index[VLIB_RX]);
-	    }
-
-	  tc = session_lookup_connection_wt6 (fib_index, &ip6->dst_address,
-					      &ip6->src_address,
-					      tcp->dst_port, tcp->src_port,
-					      TRANSPORT_PROTO_TCP,
-					      thread_index, &result);
-	}
-    }
-
-  if (is_nolookup)
-    tc =
-      (transport_connection_t *) tcp_connection_get (vnet_buffer (b)->
-						     tcp.connection_index,
-						     thread_index);
-
-  vnet_buffer (b)->tcp.seq_number = clib_net_to_host_u32 (tcp->seq_number);
-  vnet_buffer (b)->tcp.ack_number = clib_net_to_host_u32 (tcp->ack_number);
-  vnet_buffer (b)->tcp.data_offset = n_advance_bytes;
-  vnet_buffer (b)->tcp.data_len = n_data_bytes;
-  vnet_buffer (b)->tcp.seq_end = vnet_buffer (b)->tcp.seq_number
-    + n_data_bytes;
-  vnet_buffer (b)->tcp.flags = 0;
-
-  *error = result ? TCP_ERROR_NONE + result : *error;
-
-  return tcp_get_connection_from_transport (tc);
-}
-
 static inline void
 tcp_input_dispatch_buffer (tcp_main_t * tm, tcp_connection_t * tc,
 			   vlib_buffer_t * b, u16 * next,
diff --git a/src/vnet/tcp/tcp_newreno.c b/src/vnet/tcp/tcp_newreno.c
index 69dd2247132..c5ffc2a4109 100644
--- a/src/vnet/tcp/tcp_newreno.c
+++ b/src/vnet/tcp/tcp_newreno.c
@@ -14,6 +14,7 @@
  */
 
 #include <vnet/tcp/tcp.h>
+#include <vnet/tcp/tcp_inlines.h>
 
 typedef struct nwreno_cfg_
 {
diff --git a/src/vnet/tcp/tcp_output.c b/src/vnet/tcp/tcp_output.c
index d07fb2ec26e..aeeffa726c3 100644
--- a/src/vnet/tcp/tcp_output.c
+++ b/src/vnet/tcp/tcp_output.c
@@ -14,6 +14,7 @@
  */
 
 #include <vnet/tcp/tcp.h>
+#include <vnet/tcp/tcp_inlines.h>
 #include <math.h>
 
 typedef enum _tcp_output_next
@@ -166,90 +167,6 @@ tcp_window_to_advertise (tcp_connection_t * tc, tcp_state_t state)
   return tc->rcv_wnd >> tc->rcv_wscale;
 }
 
-/**
- * Write TCP options to segment.
- */
-static u32
-tcp_options_write (u8 * data, tcp_options_t * opts)
-{
-  u32 opts_len = 0;
-  u32 buf, seq_len = 4;
-
-  if (tcp_opts_mss (opts))
-    {
-      *data++ = TCP_OPTION_MSS;
-      *data++ = TCP_OPTION_LEN_MSS;
-      buf = clib_host_to_net_u16 (opts->mss);
-      clib_memcpy_fast (data, &buf, sizeof (opts->mss));
-      data += sizeof (opts->mss);
-      opts_len += TCP_OPTION_LEN_MSS;
-    }
-
-  if (tcp_opts_wscale (opts))
-    {
-      *data++ = TCP_OPTION_WINDOW_SCALE;
-      *data++ = TCP_OPTION_LEN_WINDOW_SCALE;
-      *data++ = opts->wscale;
-      opts_len += TCP_OPTION_LEN_WINDOW_SCALE;
-    }
-
-  if (tcp_opts_sack_permitted (opts))
-    {
-      *data++ = TCP_OPTION_SACK_PERMITTED;
-      *data++ = TCP_OPTION_LEN_SACK_PERMITTED;
-      opts_len += TCP_OPTION_LEN_SACK_PERMITTED;
-    }
-
-  if (tcp_opts_tstamp (opts))
-    {
-      *data++ = TCP_OPTION_TIMESTAMP;
-      *data++ = TCP_OPTION_LEN_TIMESTAMP;
-      buf = clib_host_to_net_u32 (opts->tsval);
-      clib_memcpy_fast (data, &buf, sizeof (opts->tsval));
-      data += sizeof (opts->tsval);
-      buf = clib_host_to_net_u32 (opts->tsecr);
-      clib_memcpy_fast (data, &buf, sizeof (opts->tsecr));
-      data += sizeof (opts->tsecr);
-      opts_len += TCP_OPTION_LEN_TIMESTAMP;
-    }
-
-  if (tcp_opts_sack (opts))
-    {
-      int i;
-
-      if (opts->n_sack_blocks != 0)
-	{
-	  *data++ = TCP_OPTION_SACK_BLOCK;
-	  *data++ = 2 + opts->n_sack_blocks * TCP_OPTION_LEN_SACK_BLOCK;
-	  for (i = 0; i < opts->n_sack_blocks; i++)
-	    {
-	      buf = clib_host_to_net_u32 (opts->sacks[i].start);
-	      clib_memcpy_fast (data, &buf, seq_len);
-	      data += seq_len;
-	      buf = clib_host_to_net_u32 (opts->sacks[i].end);
-	      clib_memcpy_fast (data, &buf, seq_len);
-	      data += seq_len;
-	    }
-	  opts_len += 2 + opts->n_sack_blocks * TCP_OPTION_LEN_SACK_BLOCK;
-	}
-    }
-
-  /* Terminate TCP options */
-  if (opts_len % 4)
-    {
-      *data++ = TCP_OPTION_EOL;
-      opts_len += TCP_OPTION_LEN_EOL;
-    }
-
-  /* Pad with zeroes to a u32 boundary */
-  while (opts_len % 4)
-    {
-      *data++ = TCP_OPTION_NOOP;
-      opts_len += TCP_OPTION_LEN_NOOP;
-    }
-  return opts_len;
-}
-
 static int
 tcp_make_syn_options (tcp_connection_t * tc, tcp_options_t * opts)
 {
@@ -563,7 +480,7 @@ tcp_make_ack (tcp_connection_t * tc, vlib_buffer_t * b)
 /**
  * Convert buffer to FIN-ACK
  */
-void
+static void
 tcp_make_fin (tcp_connection_t * tc, vlib_buffer_t * b)
 {
   tcp_make_ack_i (tc, b, TCP_STATE_ESTABLISHED, TCP_FLAG_FIN | TCP_FLAG_ACK);
@@ -598,7 +515,7 @@ tcp_make_syn (tcp_connection_t * tc, vlib_buffer_t * b)
 /**
  * Convert buffer to SYN-ACK
  */
-void
+static void
 tcp_make_synack (tcp_connection_t * tc, vlib_buffer_t * b)
 {
   tcp_options_t _snd_opts, *snd_opts = &_snd_opts;
diff --git a/src/vnet/tcp/tcp_packet.h b/src/vnet/tcp/tcp_packet.h
index 1e637a83271..fcc55ff549e 100644
--- a/src/vnet/tcp/tcp_packet.h
+++ b/src/vnet/tcp/tcp_packet.h
@@ -172,6 +172,219 @@ typedef struct
 #define TCP_MAX_WND_SCALE               14	/* See RFC 1323 */
 #define TCP_OPTS_ALIGN                  4
 #define TCP_OPTS_MAX_SACK_BLOCKS        3
+
+/* Modulo arithmetic for TCP sequence numbers */
+#define seq_lt(_s1, _s2) ((i32)((_s1)-(_s2)) < 0)
+#define seq_leq(_s1, _s2) ((i32)((_s1)-(_s2)) <= 0)
+#define seq_gt(_s1, _s2) ((i32)((_s1)-(_s2)) > 0)
+#define seq_geq(_s1, _s2) ((i32)((_s1)-(_s2)) >= 0)
+#define seq_max(_s1, _s2) (seq_gt((_s1), (_s2)) ? (_s1) : (_s2))
+
+/* Modulo arithmetic for timestamps */
+#define timestamp_lt(_t1, _t2) ((i32)((_t1)-(_t2)) < 0)
+#define timestamp_leq(_t1, _t2) ((i32)((_t1)-(_t2)) <= 0)
+
+/**
+ * Parse TCP header options.
+ *
+ * @param th TCP header
+ * @param to TCP options data structure to be populated
+ * @param is_syn set if packet is syn
+ * @return -1 if parsing failed
+ */
+always_inline int
+tcp_options_parse (tcp_header_t * th, tcp_options_t * to, u8 is_syn)
+{
+  const u8 *data;
+  u8 opt_len, opts_len, kind;
+  int j;
+  sack_block_t b;
+
+  opts_len = (tcp_doff (th) << 2) - sizeof (tcp_header_t);
+  data = (const u8 *) (th + 1);
+
+  /* Zero out all flags but those set in SYN */
+  to->flags &= (TCP_OPTS_FLAG_SACK_PERMITTED | TCP_OPTS_FLAG_WSCALE
+		| TCP_OPTS_FLAG_TSTAMP | TCP_OPTS_FLAG_MSS);
+
+  for (; opts_len > 0; opts_len -= opt_len, data += opt_len)
+    {
+      kind = data[0];
+
+      /* Get options length */
+      if (kind == TCP_OPTION_EOL)
+	break;
+      else if (kind == TCP_OPTION_NOOP)
+	{
+	  opt_len = 1;
+	  continue;
+	}
+      else
+	{
+	  /* broken options */
+	  if (opts_len < 2)
+	    return -1;
+	  opt_len = data[1];
+
+	  /* weird option length */
+	  if (opt_len < 2 || opt_len > opts_len)
+	    return -1;
+	}
+
+      /* Parse options */
+      switch (kind)
+	{
+	case TCP_OPTION_MSS:
+	  if (!is_syn)
+	    break;
+	  if ((opt_len == TCP_OPTION_LEN_MSS) && tcp_syn (th))
+	    {
+	      to->flags |= TCP_OPTS_FLAG_MSS;
+	      to->mss = clib_net_to_host_u16 (*(u16 *) (data + 2));
+	    }
+	  break;
+	case TCP_OPTION_WINDOW_SCALE:
+	  if (!is_syn)
+	    break;
+	  if ((opt_len == TCP_OPTION_LEN_WINDOW_SCALE) && tcp_syn (th))
+	    {
+	      to->flags |= TCP_OPTS_FLAG_WSCALE;
+	      to->wscale = data[2];
+	      if (to->wscale > TCP_MAX_WND_SCALE)
+		to->wscale = TCP_MAX_WND_SCALE;
+	    }
+	  break;
+	case TCP_OPTION_TIMESTAMP:
+	  if (is_syn)
+	    to->flags |= TCP_OPTS_FLAG_TSTAMP;
+	  if ((to->flags & TCP_OPTS_FLAG_TSTAMP)
+	      && opt_len == TCP_OPTION_LEN_TIMESTAMP)
+	    {
+	      to->tsval = clib_net_to_host_u32 (*(u32 *) (data + 2));
+	      to->tsecr = clib_net_to_host_u32 (*(u32 *) (data + 6));
+	    }
+	  break;
+	case TCP_OPTION_SACK_PERMITTED:
+	  if (!is_syn)
+	    break;
+	  if (opt_len == TCP_OPTION_LEN_SACK_PERMITTED && tcp_syn (th))
+	    to->flags |= TCP_OPTS_FLAG_SACK_PERMITTED;
+	  break;
+	case TCP_OPTION_SACK_BLOCK:
+	  /* If SACK permitted was not advertised or a SYN, break */
+	  if ((to->flags & TCP_OPTS_FLAG_SACK_PERMITTED) == 0 || tcp_syn (th))
+	    break;
+
+	  /* If too short or not correctly formatted, break */
+	  if (opt_len < 10 || ((opt_len - 2) % TCP_OPTION_LEN_SACK_BLOCK))
+	    break;
+
+	  to->flags |= TCP_OPTS_FLAG_SACK;
+	  to->n_sack_blocks = (opt_len - 2) / TCP_OPTION_LEN_SACK_BLOCK;
+	  vec_reset_length (to->sacks);
+	  for (j = 0; j < to->n_sack_blocks; j++)
+	    {
+	      b.start = clib_net_to_host_u32 (*(u32 *) (data + 2 + 8 * j));
+	      b.end = clib_net_to_host_u32 (*(u32 *) (data + 6 + 8 * j));
+	      vec_add1 (to->sacks, b);
+	    }
+	  break;
+	default:
+	  /* Nothing to see here */
+	  continue;
+	}
+    }
+  return 0;
+}
+
+/**
+ * Write TCP options to segment.
+ *
+ * @param data	buffer where to write the options
+ * @param opts	options to write
+ * @return	length of options written
+ */
+always_inline u32
+tcp_options_write (u8 * data, tcp_options_t * opts)
+{
+  u32 opts_len = 0;
+  u32 buf, seq_len = 4;
+
+  if (tcp_opts_mss (opts))
+    {
+      *data++ = TCP_OPTION_MSS;
+      *data++ = TCP_OPTION_LEN_MSS;
+      buf = clib_host_to_net_u16 (opts->mss);
+      clib_memcpy_fast (data, &buf, sizeof (opts->mss));
+      data += sizeof (opts->mss);
+      opts_len += TCP_OPTION_LEN_MSS;
+    }
+
+  if (tcp_opts_wscale (opts))
+    {
+      *data++ = TCP_OPTION_WINDOW_SCALE;
+      *data++ = TCP_OPTION_LEN_WINDOW_SCALE;
+      *data++ = opts->wscale;
+      opts_len += TCP_OPTION_LEN_WINDOW_SCALE;
+    }
+
+  if (tcp_opts_sack_permitted (opts))
+    {
+      *data++ = TCP_OPTION_SACK_PERMITTED;
+      *data++ = TCP_OPTION_LEN_SACK_PERMITTED;
+      opts_len += TCP_OPTION_LEN_SACK_PERMITTED;
+    }
+
+  if (tcp_opts_tstamp (opts))
+    {
+      *data++ = TCP_OPTION_TIMESTAMP;
+      *data++ = TCP_OPTION_LEN_TIMESTAMP;
+      buf = clib_host_to_net_u32 (opts->tsval);
+      clib_memcpy_fast (data, &buf, sizeof (opts->tsval));
+      data += sizeof (opts->tsval);
+      buf = clib_host_to_net_u32 (opts->tsecr);
+      clib_memcpy_fast (data, &buf, sizeof (opts->tsecr));
+      data += sizeof (opts->tsecr);
+      opts_len += TCP_OPTION_LEN_TIMESTAMP;
+    }
+
+  if (tcp_opts_sack (opts))
+    {
+      int i;
+
+      if (opts->n_sack_blocks != 0)
+	{
+	  *data++ = TCP_OPTION_SACK_BLOCK;
+	  *data++ = 2 + opts->n_sack_blocks * TCP_OPTION_LEN_SACK_BLOCK;
+	  for (i = 0; i < opts->n_sack_blocks; i++)
+	    {
+	      buf = clib_host_to_net_u32 (opts->sacks[i].start);
+	      clib_memcpy_fast (data, &buf, seq_len);
+	      data += seq_len;
+	      buf = clib_host_to_net_u32 (opts->sacks[i].end);
+	      clib_memcpy_fast (data, &buf, seq_len);
+	      data += seq_len;
+	    }
+	  opts_len += 2 + opts->n_sack_blocks * TCP_OPTION_LEN_SACK_BLOCK;
+	}
+    }
+
+  /* Terminate TCP options */
+  if (opts_len % 4)
+    {
+      *data++ = TCP_OPTION_EOL;
+      opts_len += TCP_OPTION_LEN_EOL;
+    }
+
+  /* Pad with zeroes to a u32 boundary */
+  while (opts_len % 4)
+    {
+      *data++ = TCP_OPTION_NOOP;
+      opts_len += TCP_OPTION_LEN_NOOP;
+    }
+  return opts_len;
+}
+
 #endif /* included_tcp_packet_h */
 
 /*
diff --git a/src/vnet/tcp/tcp_sack.c b/src/vnet/tcp/tcp_sack.c
new file mode 100644
index 00000000000..3388dd6c5b3
--- /dev/null
+++ b/src/vnet/tcp/tcp_sack.c
@@ -0,0 +1,607 @@
+/*
+ * Copyright (c) 2020 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <vnet/tcp/tcp_sack.h>
+
+static void
+scoreboard_remove_hole (sack_scoreboard_t * sb, sack_scoreboard_hole_t * hole)
+{
+  sack_scoreboard_hole_t *next, *prev;
+
+  if (hole->next != TCP_INVALID_SACK_HOLE_INDEX)
+    {
+      next = pool_elt_at_index (sb->holes, hole->next);
+      next->prev = hole->prev;
+    }
+  else
+    {
+      sb->tail = hole->prev;
+    }
+
+  if (hole->prev != TCP_INVALID_SACK_HOLE_INDEX)
+    {
+      prev = pool_elt_at_index (sb->holes, hole->prev);
+      prev->next = hole->next;
+    }
+  else
+    {
+      sb->head = hole->next;
+    }
+
+  if (scoreboard_hole_index (sb, hole) == sb->cur_rxt_hole)
+    sb->cur_rxt_hole = TCP_INVALID_SACK_HOLE_INDEX;
+
+  /* Poison the entry */
+  if (CLIB_DEBUG > 0)
+    clib_memset (hole, 0xfe, sizeof (*hole));
+
+  pool_put (sb->holes, hole);
+}
+
+static sack_scoreboard_hole_t *
+scoreboard_insert_hole (sack_scoreboard_t * sb, u32 prev_index,
+			u32 start, u32 end)
+{
+  sack_scoreboard_hole_t *hole, *next, *prev;
+  u32 hole_index;
+
+  pool_get (sb->holes, hole);
+  clib_memset (hole, 0, sizeof (*hole));
+
+  hole->start = start;
+  hole->end = end;
+  hole_index = scoreboard_hole_index (sb, hole);
+
+  prev = scoreboard_get_hole (sb, prev_index);
+  if (prev)
+    {
+      hole->prev = prev_index;
+      hole->next = prev->next;
+
+      if ((next = scoreboard_next_hole (sb, hole)))
+	next->prev = hole_index;
+      else
+	sb->tail = hole_index;
+
+      prev->next = hole_index;
+    }
+  else
+    {
+      sb->head = hole_index;
+      hole->prev = TCP_INVALID_SACK_HOLE_INDEX;
+      hole->next = TCP_INVALID_SACK_HOLE_INDEX;
+    }
+
+  return hole;
+}
+
+always_inline void
+scoreboard_update_sacked_rxt (sack_scoreboard_t * sb, u32 start, u32 end,
+			      u8 has_rxt)
+{
+  if (!has_rxt || seq_geq (start, sb->high_rxt))
+    return;
+
+  sb->rxt_sacked +=
+    seq_lt (end, sb->high_rxt) ? (end - start) : (sb->high_rxt - start);
+}
+
+always_inline void
+scoreboard_update_bytes (sack_scoreboard_t * sb, u32 ack, u32 snd_mss)
+{
+  sack_scoreboard_hole_t *left, *right;
+  u32 sacked = 0, blks = 0, old_sacked;
+
+  old_sacked = sb->sacked_bytes;
+
+  sb->last_lost_bytes = 0;
+  sb->lost_bytes = 0;
+  sb->sacked_bytes = 0;
+
+  right = scoreboard_last_hole (sb);
+  if (!right)
+    {
+      sb->sacked_bytes = sb->high_sacked - ack;
+      sb->last_sacked_bytes = sb->sacked_bytes
+	- (old_sacked - sb->last_bytes_delivered);
+      return;
+    }
+
+  if (seq_gt (sb->high_sacked, right->end))
+    {
+      sacked = sb->high_sacked - right->end;
+      blks = 1;
+    }
+
+  while (sacked < (TCP_DUPACK_THRESHOLD - 1) * snd_mss
+	 && blks < TCP_DUPACK_THRESHOLD)
+    {
+      if (right->is_lost)
+	sb->lost_bytes += scoreboard_hole_bytes (right);
+
+      left = scoreboard_prev_hole (sb, right);
+      if (!left)
+	{
+	  ASSERT (right->start == ack || sb->is_reneging);
+	  sacked += right->start - ack;
+	  right = 0;
+	  break;
+	}
+
+      sacked += right->start - left->end;
+      blks++;
+      right = left;
+    }
+
+  /* right is first lost */
+  while (right)
+    {
+      sb->lost_bytes += scoreboard_hole_bytes (right);
+      sb->last_lost_bytes += right->is_lost ? 0 : (right->end - right->start);
+      right->is_lost = 1;
+      left = scoreboard_prev_hole (sb, right);
+      if (!left)
+	{
+	  ASSERT (right->start == ack || sb->is_reneging);
+	  sacked += right->start - ack;
+	  break;
+	}
+      sacked += right->start - left->end;
+      right = left;
+    }
+
+  sb->sacked_bytes = sacked;
+  sb->last_sacked_bytes = sacked - (old_sacked - sb->last_bytes_delivered);
+}
+
+/**
+ * Figure out the next hole to retransmit
+ *
+ * Follows logic proposed in RFC6675 Sec. 4, NextSeg()
+ */
+sack_scoreboard_hole_t *
+scoreboard_next_rxt_hole (sack_scoreboard_t * sb,
+			  sack_scoreboard_hole_t * start,
+			  u8 have_unsent, u8 * can_rescue, u8 * snd_limited)
+{
+  sack_scoreboard_hole_t *hole = 0;
+
+  hole = start ? start : scoreboard_first_hole (sb);
+  while (hole && seq_leq (hole->end, sb->high_rxt) && hole->is_lost)
+    hole = scoreboard_next_hole (sb, hole);
+
+  /* Nothing, return */
+  if (!hole)
+    {
+      sb->cur_rxt_hole = TCP_INVALID_SACK_HOLE_INDEX;
+      return 0;
+    }
+
+  /* Rule (1): if higher than rxt, less than high_sacked and lost */
+  if (hole->is_lost && seq_lt (hole->start, sb->high_sacked))
+    {
+      sb->cur_rxt_hole = scoreboard_hole_index (sb, hole);
+    }
+  else
+    {
+      /* Rule (2): available unsent data */
+      if (have_unsent)
+	{
+	  sb->cur_rxt_hole = TCP_INVALID_SACK_HOLE_INDEX;
+	  return 0;
+	}
+      /* Rule (3): if hole not lost */
+      else if (seq_lt (hole->start, sb->high_sacked))
+	{
+	  /* And we didn't already retransmit it */
+	  if (seq_leq (hole->end, sb->high_rxt))
+	    {
+	      sb->cur_rxt_hole = TCP_INVALID_SACK_HOLE_INDEX;
+	      return 0;
+	    }
+	  *snd_limited = 0;
+	  sb->cur_rxt_hole = scoreboard_hole_index (sb, hole);
+	}
+      /* Rule (4): if hole beyond high_sacked */
+      else
+	{
+	  ASSERT (seq_geq (hole->start, sb->high_sacked));
+	  *snd_limited = 1;
+	  *can_rescue = 1;
+	  /* HighRxt MUST NOT be updated */
+	  return 0;
+	}
+    }
+
+  if (hole && seq_lt (sb->high_rxt, hole->start))
+    sb->high_rxt = hole->start;
+
+  return hole;
+}
+
+void
+scoreboard_init_rxt (sack_scoreboard_t * sb, u32 snd_una)
+{
+  sack_scoreboard_hole_t *hole;
+  hole = scoreboard_first_hole (sb);
+  if (hole)
+    {
+      snd_una = seq_gt (snd_una, hole->start) ? snd_una : hole->start;
+      sb->cur_rxt_hole = sb->head;
+    }
+  sb->high_rxt = snd_una;
+  sb->rescue_rxt = snd_una - 1;
+}
+
+void
+scoreboard_init (sack_scoreboard_t * sb)
+{
+  sb->head = TCP_INVALID_SACK_HOLE_INDEX;
+  sb->tail = TCP_INVALID_SACK_HOLE_INDEX;
+  sb->cur_rxt_hole = TCP_INVALID_SACK_HOLE_INDEX;
+}
+
+void
+scoreboard_clear (sack_scoreboard_t * sb)
+{
+  sack_scoreboard_hole_t *hole;
+  while ((hole = scoreboard_first_hole (sb)))
+    {
+      scoreboard_remove_hole (sb, hole);
+    }
+  ASSERT (sb->head == sb->tail && sb->head == TCP_INVALID_SACK_HOLE_INDEX);
+  ASSERT (pool_elts (sb->holes) == 0);
+  sb->sacked_bytes = 0;
+  sb->last_sacked_bytes = 0;
+  sb->last_bytes_delivered = 0;
+  sb->lost_bytes = 0;
+  sb->last_lost_bytes = 0;
+  sb->cur_rxt_hole = TCP_INVALID_SACK_HOLE_INDEX;
+  sb->is_reneging = 0;
+}
+
+void
+scoreboard_clear_reneging (sack_scoreboard_t * sb, u32 start, u32 end)
+{
+  sack_scoreboard_hole_t *last_hole;
+
+  clib_warning ("sack reneging");
+
+  scoreboard_clear (sb);
+  last_hole = scoreboard_insert_hole (sb, TCP_INVALID_SACK_HOLE_INDEX,
+				      start, end);
+  last_hole->is_lost = 1;
+  sb->tail = scoreboard_hole_index (sb, last_hole);
+  sb->high_sacked = start;
+  scoreboard_init_rxt (sb, start);
+}
+
+/**
+ * Test that scoreboard is sane after recovery
+ *
+ * Returns 1 if scoreboard is empty or if first hole beyond
+ * snd_una.
+ */
+u8
+tcp_scoreboard_is_sane_post_recovery (tcp_connection_t * tc)
+{
+  sack_scoreboard_hole_t *hole;
+  hole = scoreboard_first_hole (&tc->sack_sb);
+  return (!hole || (seq_geq (hole->start, tc->snd_una)
+		    && seq_lt (hole->end, tc->snd_nxt)));
+}
+
+void
+tcp_rcv_sacks (tcp_connection_t * tc, u32 ack)
+{
+  sack_scoreboard_hole_t *hole, *next_hole;
+  sack_scoreboard_t *sb = &tc->sack_sb;
+  sack_block_t *blk, *rcv_sacks;
+  u32 blk_index = 0, i, j;
+  u8 has_rxt;
+
+  sb->last_sacked_bytes = 0;
+  sb->last_bytes_delivered = 0;
+  sb->rxt_sacked = 0;
+
+  if (!tcp_opts_sack (&tc->rcv_opts) && !sb->sacked_bytes
+      && sb->head == TCP_INVALID_SACK_HOLE_INDEX)
+    return;
+
+  has_rxt = tcp_in_cong_recovery (tc);
+
+  /* Remove invalid blocks */
+  blk = tc->rcv_opts.sacks;
+  while (blk < vec_end (tc->rcv_opts.sacks))
+    {
+      if (seq_lt (blk->start, blk->end)
+	  && seq_gt (blk->start, tc->snd_una)
+	  && seq_gt (blk->start, ack) && seq_leq (blk->end, tc->snd_nxt))
+	{
+	  blk++;
+	  continue;
+	}
+      vec_del1 (tc->rcv_opts.sacks, blk - tc->rcv_opts.sacks);
+    }
+
+  /* Add block for cumulative ack */
+  if (seq_gt (ack, tc->snd_una))
+    {
+      vec_add2 (tc->rcv_opts.sacks, blk, 1);
+      blk->start = tc->snd_una;
+      blk->end = ack;
+    }
+
+  if (vec_len (tc->rcv_opts.sacks) == 0)
+    return;
+
+  tcp_scoreboard_trace_add (tc, ack);
+
+  /* Make sure blocks are ordered */
+  rcv_sacks = tc->rcv_opts.sacks;
+  for (i = 0; i < vec_len (rcv_sacks); i++)
+    for (j = i + 1; j < vec_len (rcv_sacks); j++)
+      if (seq_lt (rcv_sacks[j].start, rcv_sacks[i].start))
+	{
+	  sack_block_t tmp = rcv_sacks[i];
+	  rcv_sacks[i] = rcv_sacks[j];
+	  rcv_sacks[j] = tmp;
+	}
+
+  if (sb->head == TCP_INVALID_SACK_HOLE_INDEX)
+    {
+      /* Handle reneging as a special case */
+      if (PREDICT_FALSE (sb->is_reneging))
+	{
+	  /* No holes, only sacked bytes */
+	  if (seq_leq (tc->snd_nxt, sb->high_sacked))
+	    {
+	      /* No progress made so return */
+	      if (seq_leq (ack, tc->snd_una))
+		return;
+
+	      /* Update sacked bytes delivered and return */
+	      sb->last_bytes_delivered = ack - tc->snd_una;
+	      sb->sacked_bytes -= sb->last_bytes_delivered;
+	      sb->is_reneging = seq_lt (ack, sb->high_sacked);
+	      return;
+	    }
+
+	  /* New hole above high sacked. Add it and process normally */
+	  hole = scoreboard_insert_hole (sb, TCP_INVALID_SACK_HOLE_INDEX,
+					 sb->high_sacked, tc->snd_nxt);
+	  sb->tail = scoreboard_hole_index (sb, hole);
+	}
+      /* Not reneging and no holes. Insert the first that covers all
+       * outstanding bytes */
+      else
+	{
+	  hole = scoreboard_insert_hole (sb, TCP_INVALID_SACK_HOLE_INDEX,
+					 tc->snd_una, tc->snd_nxt);
+	  sb->tail = scoreboard_hole_index (sb, hole);
+	}
+      sb->high_sacked = rcv_sacks[vec_len (rcv_sacks) - 1].end;
+    }
+  else
+    {
+      /* If we have holes but snd_nxt is beyond the last hole, update
+       * last hole end or add new hole after high sacked */
+      hole = scoreboard_last_hole (sb);
+      if (seq_gt (tc->snd_nxt, hole->end))
+	{
+	  if (seq_geq (hole->start, sb->high_sacked))
+	    {
+	      hole->end = tc->snd_nxt;
+	    }
+	  /* New hole after high sacked block */
+	  else if (seq_lt (sb->high_sacked, tc->snd_nxt))
+	    {
+	      scoreboard_insert_hole (sb, sb->tail, sb->high_sacked,
+				      tc->snd_nxt);
+	    }
+	}
+
+      /* Keep track of max byte sacked for when the last hole
+       * is acked */
+      sb->high_sacked = seq_max (rcv_sacks[vec_len (rcv_sacks) - 1].end,
+				 sb->high_sacked);
+    }
+
+  /* Walk the holes with the SACK blocks */
+  hole = pool_elt_at_index (sb->holes, sb->head);
+
+  if (PREDICT_FALSE (sb->is_reneging))
+    {
+      sb->last_bytes_delivered += clib_min (hole->start - tc->snd_una,
+					    ack - tc->snd_una);
+      sb->is_reneging = seq_lt (ack, hole->start);
+    }
+
+  while (hole && blk_index < vec_len (rcv_sacks))
+    {
+      blk = &rcv_sacks[blk_index];
+      if (seq_leq (blk->start, hole->start))
+	{
+	  /* Block covers hole. Remove hole */
+	  if (seq_geq (blk->end, hole->end))
+	    {
+	      next_hole = scoreboard_next_hole (sb, hole);
+
+	      /* If covered by ack, compute delivered bytes */
+	      if (blk->end == ack)
+		{
+		  u32 sacked = next_hole ? next_hole->start : sb->high_sacked;
+		  if (PREDICT_FALSE (seq_lt (ack, sacked)))
+		    {
+		      sb->last_bytes_delivered += ack - hole->end;
+		      sb->is_reneging = 1;
+		    }
+		  else
+		    {
+		      sb->last_bytes_delivered += sacked - hole->end;
+		      sb->is_reneging = 0;
+		    }
+		}
+	      scoreboard_update_sacked_rxt (sb, hole->start, hole->end,
+					    has_rxt);
+	      scoreboard_remove_hole (sb, hole);
+	      hole = next_hole;
+	    }
+	  /* Partial 'head' overlap */
+	  else
+	    {
+	      if (seq_gt (blk->end, hole->start))
+		{
+		  scoreboard_update_sacked_rxt (sb, hole->start, blk->end,
+						has_rxt);
+		  hole->start = blk->end;
+		}
+	      blk_index++;
+	    }
+	}
+      else
+	{
+	  /* Hole must be split */
+	  if (seq_lt (blk->end, hole->end))
+	    {
+	      u32 hole_index = scoreboard_hole_index (sb, hole);
+	      next_hole = scoreboard_insert_hole (sb, hole_index, blk->end,
+						  hole->end);
+	      /* Pool might've moved */
+	      hole = scoreboard_get_hole (sb, hole_index);
+	      hole->end = blk->start;
+
+	      scoreboard_update_sacked_rxt (sb, blk->start, blk->end,
+					    has_rxt);
+
+	      blk_index++;
+	      ASSERT (hole->next == scoreboard_hole_index (sb, next_hole));
+	    }
+	  else if (seq_lt (blk->start, hole->end))
+	    {
+	      scoreboard_update_sacked_rxt (sb, blk->start, hole->end,
+					    has_rxt);
+	      hole->end = blk->start;
+	    }
+	  hole = scoreboard_next_hole (sb, hole);
+	}
+    }
+
+  scoreboard_update_bytes (sb, ack, tc->snd_mss);
+
+  ASSERT (sb->last_sacked_bytes <= sb->sacked_bytes || tcp_in_recovery (tc));
+  ASSERT (sb->sacked_bytes == 0 || tcp_in_recovery (tc)
+	  || sb->sacked_bytes <= tc->snd_nxt - seq_max (tc->snd_una, ack));
+  ASSERT (sb->last_sacked_bytes + sb->lost_bytes <= tc->snd_nxt
+	  - seq_max (tc->snd_una, ack) || tcp_in_recovery (tc));
+  ASSERT (sb->head == TCP_INVALID_SACK_HOLE_INDEX || tcp_in_recovery (tc)
+	  || sb->is_reneging || sb->holes[sb->head].start == ack);
+  ASSERT (sb->last_lost_bytes <= sb->lost_bytes);
+  ASSERT ((ack - tc->snd_una) + sb->last_sacked_bytes
+	  - sb->last_bytes_delivered >= sb->rxt_sacked);
+  ASSERT ((ack - tc->snd_una) >= tc->sack_sb.last_bytes_delivered
+	  || (tc->flags & TCP_CONN_FINSNT));
+
+  TCP_EVT (TCP_EVT_CC_SCOREBOARD, tc);
+}
+
+static u8
+tcp_sack_vector_is_sane (sack_block_t * sacks)
+{
+  int i;
+  for (i = 1; i < vec_len (sacks); i++)
+    {
+      if (sacks[i - 1].end == sacks[i].start)
+	return 0;
+    }
+  return 1;
+}
+
+/**
+ * Build SACK list as per RFC2018.
+ *
+ * Makes sure the first block contains the segment that generated the current
+ * ACK and the following ones are the ones most recently reported in SACK
+ * blocks.
+ *
+ * @param tc TCP connection for which the SACK list is updated
+ * @param start Start sequence number of the newest SACK block
+ * @param end End sequence of the newest SACK block
+ */
+void
+tcp_update_sack_list (tcp_connection_t * tc, u32 start, u32 end)
+{
+  sack_block_t *new_list = tc->snd_sacks_fl, *block = 0;
+  int i;
+
+  /* If the first segment is ooo add it to the list. Last write might've moved
+   * rcv_nxt over the first segment. */
+  if (seq_lt (tc->rcv_nxt, start))
+    {
+      vec_add2 (new_list, block, 1);
+      block->start = start;
+      block->end = end;
+    }
+
+  /* Find the blocks still worth keeping. */
+  for (i = 0; i < vec_len (tc->snd_sacks); i++)
+    {
+      /* Discard if rcv_nxt advanced beyond current block */
+      if (seq_leq (tc->snd_sacks[i].start, tc->rcv_nxt))
+	continue;
+
+      /* Merge or drop if segment overlapped by the new segment */
+      if (block && (seq_geq (tc->snd_sacks[i].end, new_list[0].start)
+		    && seq_leq (tc->snd_sacks[i].start, new_list[0].end)))
+	{
+	  if (seq_lt (tc->snd_sacks[i].start, new_list[0].start))
+	    new_list[0].start = tc->snd_sacks[i].start;
+	  if (seq_lt (new_list[0].end, tc->snd_sacks[i].end))
+	    new_list[0].end = tc->snd_sacks[i].end;
+	  continue;
+	}
+
+      /* Save to new SACK list if we have space. */
+      if (vec_len (new_list) < TCP_MAX_SACK_BLOCKS)
+	vec_add1 (new_list, tc->snd_sacks[i]);
+    }
+
+  ASSERT (vec_len (new_list) <= TCP_MAX_SACK_BLOCKS);
+
+  /* Replace old vector with new one */
+  vec_reset_length (tc->snd_sacks);
+  tc->snd_sacks_fl = tc->snd_sacks;
+  tc->snd_sacks = new_list;
+
+  /* Segments should not 'touch' */
+  ASSERT (tcp_sack_vector_is_sane (tc->snd_sacks));
+}
+
+u32
+tcp_sack_list_bytes (tcp_connection_t * tc)
+{
+  u32 bytes = 0, i;
+  for (i = 0; i < vec_len (tc->snd_sacks); i++)
+    bytes += tc->snd_sacks[i].end - tc->snd_sacks[i].start;
+  return bytes;
+}
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/vnet/tcp/tcp_sack.h b/src/vnet/tcp/tcp_sack.h
new file mode 100644
index 00000000000..1c3fa95510b
--- /dev/null
+++ b/src/vnet/tcp/tcp_sack.h
@@ -0,0 +1,126 @@
+/*
+ * Copyright (c) 2020 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef SRC_VNET_TCP_TCP_SACK_H_
+#define SRC_VNET_TCP_TCP_SACK_H_
+
+#include <vnet/tcp/tcp_types.h>
+
+always_inline u32
+scoreboard_hole_index (sack_scoreboard_t * sb, sack_scoreboard_hole_t * hole)
+{
+  ASSERT (!pool_is_free_index (sb->holes, hole - sb->holes));
+  return hole - sb->holes;
+}
+
+always_inline u32
+scoreboard_hole_bytes (sack_scoreboard_hole_t * hole)
+{
+  return hole->end - hole->start;
+}
+
+always_inline sack_scoreboard_hole_t *
+scoreboard_get_hole (sack_scoreboard_t * sb, u32 index)
+{
+  if (index != TCP_INVALID_SACK_HOLE_INDEX)
+    return pool_elt_at_index (sb->holes, index);
+  return 0;
+}
+
+always_inline sack_scoreboard_hole_t *
+scoreboard_next_hole (sack_scoreboard_t * sb, sack_scoreboard_hole_t * hole)
+{
+  if (hole->next != TCP_INVALID_SACK_HOLE_INDEX)
+    return pool_elt_at_index (sb->holes, hole->next);
+  return 0;
+}
+
+always_inline sack_scoreboard_hole_t *
+scoreboard_prev_hole (sack_scoreboard_t * sb, sack_scoreboard_hole_t * hole)
+{
+  if (hole->prev != TCP_INVALID_SACK_HOLE_INDEX)
+    return pool_elt_at_index (sb->holes, hole->prev);
+  return 0;
+}
+
+always_inline sack_scoreboard_hole_t *
+scoreboard_first_hole (sack_scoreboard_t * sb)
+{
+  if (sb->head != TCP_INVALID_SACK_HOLE_INDEX)
+    return pool_elt_at_index (sb->holes, sb->head);
+  return 0;
+}
+
+always_inline sack_scoreboard_hole_t *
+scoreboard_last_hole (sack_scoreboard_t * sb)
+{
+  if (sb->tail != TCP_INVALID_SACK_HOLE_INDEX)
+    return pool_elt_at_index (sb->holes, sb->tail);
+  return 0;
+}
+
+#if TCP_SCOREBOARD_TRACE
+#define tcp_scoreboard_trace_add(_tc, _ack) 				\
+{									\
+    static u64 _group = 0;						\
+    sack_scoreboard_t *_sb = &_tc->sack_sb;				\
+    sack_block_t *_sack, *_sacks;					\
+    scoreboard_trace_elt_t *_elt;					\
+    int i;								\
+    _group++;								\
+    _sacks = _tc->rcv_opts.sacks;					\
+    for (i = 0; i < vec_len (_sacks); i++) 				\
+      {									\
+	_sack = &_sacks[i];						\
+	vec_add2 (_sb->trace, _elt, 1);					\
+	_elt->start = _sack->start;					\
+	_elt->end = _sack->end;						\
+	_elt->ack = _elt->end == _ack ? _ack : 0;			\
+	_elt->snd_una_max = _elt->end == _ack ? _tc->snd_una_max : 0;	\
+	_elt->group = _group;						\
+      }									\
+}
+#else
+#define tcp_scoreboard_trace_add(_tc, _ack)
+#endif
+
+sack_scoreboard_hole_t *scoreboard_next_rxt_hole (sack_scoreboard_t * sb,
+						  sack_scoreboard_hole_t *
+						  start, u8 have_sent_1_smss,
+						  u8 * can_rescue,
+						  u8 * snd_limited);
+void scoreboard_clear (sack_scoreboard_t * sb);
+void scoreboard_clear_reneging (sack_scoreboard_t * sb, u32 start, u32 end);
+void scoreboard_init (sack_scoreboard_t * sb);
+void scoreboard_init_rxt (sack_scoreboard_t * sb, u32 snd_una);
+
+format_function_t format_tcp_scoreboard;
+
+/* Made public for unit testing only */
+void tcp_update_sack_list (tcp_connection_t * tc, u32 start, u32 end);
+u32 tcp_sack_list_bytes (tcp_connection_t * tc);
+void tcp_rcv_sacks (tcp_connection_t * tc, u32 ack);
+u8 *tcp_scoreboard_replay (u8 * s, tcp_connection_t * tc, u8 verbose);
+u8 tcp_scoreboard_is_sane_post_recovery (tcp_connection_t * tc);
+
+#endif /* SRC_VNET_TCP_TCP_SACK_H_ */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */
diff --git a/src/vnet/tcp/tcp_types.h b/src/vnet/tcp/tcp_types.h
new file mode 100644
index 00000000000..ccb7ae86aed
--- /dev/null
+++ b/src/vnet/tcp/tcp_types.h
@@ -0,0 +1,451 @@
+/*
+ * Copyright (c) 2020 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef SRC_VNET_TCP_TCP_TYPES_H_
+#define SRC_VNET_TCP_TCP_TYPES_H_
+
+#include <vppinfra/clib.h>
+#include <vppinfra/rbtree.h>
+#include <vnet/tcp/tcp_packet.h>
+#include <vnet/session/transport.h>
+
+#define TCP_TICK 0.001			/**< TCP tick period (s) */
+#define THZ (u32) (1/TCP_TICK)		/**< TCP tick frequency */
+#define TCP_TSTAMP_RESOLUTION TCP_TICK	/**< Time stamp resolution */
+#define TCP_PAWS_IDLE 24 * 24 * 60 * 60 * THZ /**< 24 days */
+#define TCP_FIB_RECHECK_PERIOD	1 * THZ	/**< Recheck every 1s */
+#define TCP_MAX_OPTION_SPACE 40
+#define TCP_CC_DATA_SZ 24
+#define TCP_MAX_GSO_SZ 65536
+#define TCP_RXT_MAX_BURST 10
+
+#define TCP_DUPACK_THRESHOLD 	3
+#define TCP_IW_N_SEGMENTS 	10
+#define TCP_ALWAYS_ACK		1	/**< On/off delayed acks */
+#define TCP_USE_SACKS		1	/**< Disable only for testing */
+
+/** TCP FSM state definitions as per RFC793. */
+#define foreach_tcp_fsm_state   \
+  _(CLOSED, "CLOSED")           \
+  _(LISTEN, "LISTEN")           \
+  _(SYN_SENT, "SYN_SENT")       \
+  _(SYN_RCVD, "SYN_RCVD")       \
+  _(ESTABLISHED, "ESTABLISHED") \
+  _(CLOSE_WAIT, "CLOSE_WAIT")   \
+  _(FIN_WAIT_1, "FIN_WAIT_1")   \
+  _(LAST_ACK, "LAST_ACK")       \
+  _(CLOSING, "CLOSING")         \
+  _(FIN_WAIT_2, "FIN_WAIT_2")   \
+  _(TIME_WAIT, "TIME_WAIT")
+
+typedef enum _tcp_state
+{
+#define _(sym, str) TCP_STATE_##sym,
+  foreach_tcp_fsm_state
+#undef _
+  TCP_N_STATES
+} tcp_state_t;
+
+/** TCP timers */
+#define foreach_tcp_timer               \
+  _(RETRANSMIT, "RETRANSMIT")           \
+  _(DELACK, "DELAYED ACK")              \
+  _(PERSIST, "PERSIST")                 \
+  _(WAITCLOSE, "WAIT CLOSE")            \
+  _(RETRANSMIT_SYN, "RETRANSMIT SYN")   \
+
+typedef enum _tcp_timers
+{
+#define _(sym, str) TCP_TIMER_##sym,
+  foreach_tcp_timer
+#undef _
+  TCP_N_TIMERS
+} tcp_timers_e;
+
+#define TCP_TIMER_HANDLE_INVALID ((u32) ~0)
+
+#define TCP_TIMER_TICK		0.1		/**< Timer tick in seconds */
+#define TCP_TO_TIMER_TICK       TCP_TICK*10	/**< Factor for converting
+						     ticks to timer ticks */
+
+#define TCP_RTO_MAX 60 * THZ	/* Min max RTO (60s) as per RFC6298 */
+#define TCP_RTO_MIN 0.2 * THZ	/* Min RTO (200ms) - lower than standard */
+#define TCP_RTT_MAX 30 * THZ	/* 30s (probably too much) */
+#define TCP_RTO_SYN_RETRIES 3	/* SYN retries without doubling RTO */
+#define TCP_RTO_INIT 1 * THZ	/* Initial retransmit timer */
+#define TCP_RTO_BOFF_MAX 8	/* Max number of retries before reset */
+#define TCP_ESTABLISH_TIME (60 * THZ)	/* Connection establish timeout */
+
+/** Connection configuration flags */
+#define foreach_tcp_cfg_flag 			\
+  _(RATE_SAMPLE, "Rate sampling")		\
+  _(NO_CSUM_OFFLOAD, "No csum offload")    	\
+  _(NO_TSO, "TSO off")				\
+  _(TSO, "TSO")					\
+  _(NO_ENDPOINT,"No endpoint")			\
+
+typedef enum tcp_cfg_flag_bits_
+{
+#define _(sym, str) TCP_CFG_F_##sym##_BIT,
+  foreach_tcp_cfg_flag
+#undef _
+  TCP_CFG_N_FLAG_BITS
+} tcp_cfg_flag_bits_e;
+
+typedef enum tcp_cfg_flag_
+{
+#define _(sym, str) TCP_CFG_F_##sym = 1 << TCP_CFG_F_##sym##_BIT,
+  foreach_tcp_cfg_flag
+#undef _
+  TCP_CFG_N_FLAGS
+} tcp_cfg_flags_e;
+
+/** TCP connection flags */
+#define foreach_tcp_connection_flag             \
+  _(SNDACK, "Send ACK")                         \
+  _(FINSNT, "FIN sent")				\
+  _(RECOVERY, "Recovery")                    	\
+  _(FAST_RECOVERY, "Fast Recovery")		\
+  _(DCNT_PENDING, "Disconnect pending")		\
+  _(HALF_OPEN_DONE, "Half-open completed")	\
+  _(FINPNDG, "FIN pending")			\
+  _(RXT_PENDING, "Retransmit pending")		\
+  _(FRXT_FIRST, "Retransmit first")		\
+  _(DEQ_PENDING, "Dequeue pending ")		\
+  _(PSH_PENDING, "PSH pending")			\
+  _(FINRCVD, "FIN received")			\
+  _(ZERO_RWND_SENT, "Zero RWND sent")		\
+
+typedef enum tcp_connection_flag_bits_
+{
+#define _(sym, str) TCP_CONN_##sym##_BIT,
+  foreach_tcp_connection_flag
+#undef _
+  TCP_CONN_N_FLAG_BITS
+} tcp_connection_flag_bits_e;
+
+typedef enum tcp_connection_flag_
+{
+#define _(sym, str) TCP_CONN_##sym = 1 << TCP_CONN_##sym##_BIT,
+  foreach_tcp_connection_flag
+#undef _
+  TCP_CONN_N_FLAGS
+} tcp_connection_flags_e;
+
+#define TCP_SCOREBOARD_TRACE (0)
+#define TCP_MAX_SACK_BLOCKS 256	/**< Max number of SACK blocks stored */
+#define TCP_INVALID_SACK_HOLE_INDEX ((u32)~0)
+
+typedef struct _scoreboard_trace_elt
+{
+  u32 start;
+  u32 end;
+  u32 ack;
+  u32 snd_una_max;
+  u32 group;
+} scoreboard_trace_elt_t;
+
+typedef struct _sack_scoreboard_hole
+{
+  u32 next;		/**< Index for next entry in linked list */
+  u32 prev;		/**< Index for previous entry in linked list */
+  u32 start;		/**< Start sequence number */
+  u32 end;		/**< End sequence number */
+  u8 is_lost;		/**< Mark hole as lost */
+} sack_scoreboard_hole_t;
+
+typedef struct _sack_scoreboard
+{
+  sack_scoreboard_hole_t *holes;	/**< Pool of holes */
+  u32 head;				/**< Index of first entry */
+  u32 tail;				/**< Index of last entry */
+  u32 sacked_bytes;			/**< Number of bytes sacked in sb */
+  u32 last_sacked_bytes;		/**< Number of bytes last sacked */
+  u32 last_bytes_delivered;		/**< Sack bytes delivered to app */
+  u32 rxt_sacked;			/**< Rxt bytes last delivered */
+  u32 high_sacked;			/**< Highest byte sacked (fack) */
+  u32 high_rxt;				/**< Highest retransmitted sequence */
+  u32 rescue_rxt;			/**< Rescue sequence number */
+  u32 lost_bytes;			/**< Bytes lost as per RFC6675 */
+  u32 last_lost_bytes;			/**< Number of bytes last lost */
+  u32 cur_rxt_hole;			/**< Retransmitting from this hole */
+  u8 is_reneging;
+
+#if TCP_SCOREBOARD_TRACE
+  scoreboard_trace_elt_t *trace;
+#endif
+
+} sack_scoreboard_t;
+
+#define TCP_BTS_INVALID_INDEX	((u32)~0)
+
+typedef enum tcp_bts_flags_
+{
+  TCP_BTS_IS_RXT = 1,
+  TCP_BTS_IS_APP_LIMITED = 1 << 1,
+  TCP_BTS_IS_SACKED = 1 << 2,
+  TCP_BTS_IS_RXT_LOST = 1 << 3,
+} __clib_packed tcp_bts_flags_t;
+
+typedef struct tcp_bt_sample_
+{
+  u32 next;			/**< Next sample index in list */
+  u32 prev;			/**< Previous sample index in list */
+  u32 min_seq;			/**< Min seq number in sample */
+  u32 max_seq;			/**< Max seq number. Set for rxt samples */
+  u64 delivered;		/**< Total delivered bytes for sample */
+  f64 delivered_time;		/**< Delivered time when sample taken */
+  f64 tx_time;			/**< Transmit time for the burst */
+  f64 first_tx_time;		/**< Connection first tx time at tx */
+  u64 tx_in_flight;		/**< In flight at tx time */
+  u64 tx_lost;			/**< Lost at tx time */
+  tcp_bts_flags_t flags;	/**< Sample flag */
+} tcp_bt_sample_t;
+
+typedef struct tcp_rate_sample_
+{
+  u64 prior_delivered;		/**< Delivered of sample used for rate, i.e.,
+				     total bytes delivered at prior_time */
+  f64 prior_time;		/**< Delivered time of sample used for rate */
+  f64 interval_time;		/**< Time to ack the bytes delivered */
+  f64 rtt_time;			/**< RTT for sample */
+  u64 tx_in_flight;		/**< In flight at (re)transmit time */
+  u64 tx_lost;			/**< Lost over interval */
+  u32 delivered;		/**< Bytes delivered in interval_time */
+  u32 acked_and_sacked;		/**< Bytes acked + sacked now */
+  u32 last_lost;		/**< Bytes lost now */
+  u32 lost;			/**< Number of bytes lost over interval */
+  tcp_bts_flags_t flags;	/**< Rate sample flags from bt sample */
+} tcp_rate_sample_t;
+
+typedef struct tcp_byte_tracker_
+{
+  tcp_bt_sample_t *samples;	/**< Pool of samples */
+  rb_tree_t sample_lookup;	/**< Rbtree for sample lookup by min_seq */
+  u32 head;			/**< Head of samples linked list */
+  u32 tail;			/**< Tail of samples linked list */
+  u32 last_ooo;			/**< Cached last ooo sample */
+} tcp_byte_tracker_t;
+
+typedef enum _tcp_cc_algorithm_type
+{
+  TCP_CC_NEWRENO,
+  TCP_CC_CUBIC,
+  TCP_CC_LAST = TCP_CC_CUBIC
+} tcp_cc_algorithm_type_e;
+
+typedef struct _tcp_cc_algorithm tcp_cc_algorithm_t;
+
+typedef enum _tcp_cc_ack_t
+{
+  TCP_CC_ACK,
+  TCP_CC_DUPACK,
+  TCP_CC_PARTIALACK
+} tcp_cc_ack_t;
+
+typedef enum tcp_cc_event_
+{
+  TCP_CC_EVT_START_TX,
+} tcp_cc_event_t;
+
+/*
+ * As per RFC4898 tcpEStatsStackSoftErrors
+ */
+typedef struct tcp_errors_
+{
+  u32 below_data_wnd;	/**< All data in seg is below snd_una */
+  u32 above_data_wnd;	/**< Some data in segment is above snd_wnd */
+  u32 below_ack_wnd;	/**< Acks for data below snd_una */
+  u32 above_ack_wnd;	/**< Acks for data not sent */
+} tcp_errors_t;
+
+typedef struct _tcp_connection
+{
+  CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);
+  transport_connection_t connection;  /**< Common transport data. First! */
+
+  u8 state;			/**< TCP state as per tcp_state_t */
+  u8 cfg_flags;			/**< Connection configuration flags */
+  u16 flags;			/**< Connection flags (see tcp_conn_flags_e) */
+  u32 timers[TCP_N_TIMERS];	/**< Timer handles into timer wheel */
+
+  u64 segs_in;		/** RFC4022/4898 tcpHCInSegs/tcpEStatsPerfSegsIn */
+  u64 bytes_in;		/** RFC4898 tcpEStatsPerfHCDataOctetsIn */
+  u64 segs_out;		/** RFC4898 tcpEStatsPerfSegsOut */
+  u64 bytes_out;	/** RFC4898 tcpEStatsPerfHCDataOctetsOut */
+
+  /** Send sequence variables RFC793 */
+  u32 snd_una;		/**< oldest unacknowledged sequence number */
+  u32 snd_una_max;	/**< newest unacknowledged sequence number + 1*/
+  u32 snd_wnd;		/**< send window */
+  u32 snd_wl1;		/**< seq number used for last snd.wnd update */
+  u32 snd_wl2;		/**< ack number used for last snd.wnd update */
+  u32 snd_nxt;		/**< next seq number to be sent */
+  u16 snd_mss;		/**< Effective send max seg (data) size */
+
+  u64 data_segs_in;	/** RFC4898 tcpEStatsPerfDataSegsIn */
+  u64 data_segs_out;	/** RFC4898 tcpEStatsPerfDataSegsOut */
+
+  /** Receive sequence variables RFC793 */
+  u32 rcv_nxt;		/**< next sequence number expected */
+  u32 rcv_wnd;		/**< receive window we expect */
+
+  u32 rcv_las;		/**< rcv_nxt at last ack sent/rcv_wnd update */
+  u32 iss;		/**< initial sent sequence */
+  u32 irs;		/**< initial remote sequence */
+
+  /* Options */
+  u8 snd_opts_len;		/**< Tx options len */
+  u8 rcv_wscale;		/**< Window scale to advertise to peer */
+  u8 snd_wscale;		/**< Window scale to use when sending */
+  u32 tsval_recent;		/**< Last timestamp received */
+  u32 tsval_recent_age;		/**< When last updated tstamp_recent*/
+  tcp_options_t snd_opts;	/**< Tx options for connection */
+  tcp_options_t rcv_opts;	/**< Rx options for connection */
+
+  sack_block_t *snd_sacks;	/**< Vector of SACKs to send. XXX Fixed size? */
+  u8 snd_sack_pos;		/**< Position in vec of first block to send */
+  sack_block_t *snd_sacks_fl;	/**< Vector for building new list */
+  sack_scoreboard_t sack_sb;	/**< SACK "scoreboard" that tracks holes */
+
+  u16 rcv_dupacks;	/**< Number of recent DUPACKs received */
+  u32 dupacks_in;	/**< RFC4898 tcpEStatsStackDupAcksIn*/
+  u8 pending_dupacks;	/**< Number of DUPACKs to be sent */
+  u32 dupacks_out;	/**< RFC4898 tcpEStatsPathDupAcksOut */
+
+  /* Congestion control */
+  u32 cwnd;		/**< Congestion window */
+  u32 cwnd_acc_bytes;	/**< Bytes accumulated for cwnd increment */
+  u32 ssthresh;		/**< Slow-start threshold */
+  u32 prev_ssthresh;	/**< ssthresh before congestion */
+  u32 prev_cwnd;	/**< ssthresh before congestion */
+  u32 bytes_acked;	/**< Bytes acknowledged by current segment */
+  u32 burst_acked;	/**< Bytes acknowledged in current burst */
+  u32 snd_rxt_bytes;	/**< Retransmitted bytes during current cc event */
+  u32 snd_rxt_ts;	/**< Timestamp when first packet is retransmitted */
+  u32 prr_delivered;	/**< RFC6937 bytes delivered during current event */
+  u32 prr_start;	/**< snd_una when prr starts */
+  u32 rxt_delivered;	/**< Rxt bytes delivered during current cc event */
+  u32 rxt_head;		/**< snd_una last time we re rxted the head */
+  u32 tsecr_last_ack;	/**< Timestamp echoed to us in last healthy ACK */
+  u32 snd_congestion;	/**< snd_una_max when congestion is detected */
+  u32 tx_fifo_size;	/**< Tx fifo size. Used to constrain cwnd */
+  tcp_cc_algorithm_t *cc_algo;	/**< Congestion control algorithm */
+  u8 cc_data[TCP_CC_DATA_SZ];	/**< Congestion control algo private data */
+
+  u32 fr_occurences;	/**< fast-retransmit occurrences RFC4898
+			     tcpEStatsStackFastRetran */
+  u32 tr_occurences;	/**< timer-retransmit occurrences */
+  u64 bytes_retrans;	/**< RFC4898 tcpEStatsPerfOctetsRetrans */
+  u64 segs_retrans;	/**< RFC4898 tcpEStatsPerfSegsRetrans*/
+
+  /* RTT and RTO */
+  u32 rto;		/**< Retransmission timeout */
+  u32 rto_boff;		/**< Index for RTO backoff */
+  u32 srtt;		/**< Smoothed RTT */
+  u32 rttvar;		/**< Smoothed mean RTT difference. Approximates variance */
+  u32 rtt_seq;		/**< Sequence number for tracked ACK */
+  f64 rtt_ts;		/**< Timestamp for tracked ACK */
+  f64 mrtt_us;		/**< High precision mrtt from tracked acks */
+
+  u32 psh_seq;		/**< Add psh header for seg that includes this */
+  u32 next_node_index;	/**< Can be used to control next node in output */
+  u32 next_node_opaque;	/**< Opaque to pass to next node */
+  u32 limited_transmit;	/**< snd_nxt when limited transmit starts */
+  u32 sw_if_index;	/**< Interface for the connection */
+
+  /* Delivery rate estimation */
+  u64 delivered;		/**< Total bytes delivered to peer */
+  u64 app_limited;		/**< Delivered when app-limited detected */
+  f64 delivered_time;		/**< Time last bytes were acked */
+  f64 first_tx_time;		/**< Send time for recently delivered/sent */
+  u64 lost;			/**< Total bytes lost */
+  tcp_byte_tracker_t *bt;	/**< Tx byte tracker */
+
+  tcp_errors_t errors;	/**< Soft connection errors */
+
+  f64 start_ts;		/**< Timestamp when connection initialized */
+  u32 last_fib_check;	/**< Last time we checked fib route for peer */
+  u16 mss;		/**< Our max seg size that includes options */
+  u32 timestamp_delta;	/**< Offset for timestamp */
+  u32 ipv6_flow_label;	/**< flow label for ipv6 header */
+
+#define rst_state snd_wl1
+} tcp_connection_t;
+
+/* *INDENT-OFF* */
+struct _tcp_cc_algorithm
+{
+  const char *name;
+  uword (*unformat_cfg) (unformat_input_t * input);
+  void (*init) (tcp_connection_t * tc);
+  void (*cleanup) (tcp_connection_t * tc);
+  void (*rcv_ack) (tcp_connection_t * tc, tcp_rate_sample_t *rs);
+  void (*rcv_cong_ack) (tcp_connection_t * tc, tcp_cc_ack_t ack,
+			tcp_rate_sample_t *rs);
+  void (*congestion) (tcp_connection_t * tc);
+  void (*loss) (tcp_connection_t * tc);
+  void (*recovered) (tcp_connection_t * tc);
+  void (*undo_recovery) (tcp_connection_t * tc);
+  void (*event) (tcp_connection_t *tc, tcp_cc_event_t evt);
+  u64 (*get_pacing_rate) (tcp_connection_t *tc);
+};
+/* *INDENT-ON* */
+
+#define tcp_fastrecovery_on(tc) (tc)->flags |= TCP_CONN_FAST_RECOVERY
+#define tcp_fastrecovery_off(tc) (tc)->flags &= ~TCP_CONN_FAST_RECOVERY
+#define tcp_recovery_on(tc) (tc)->flags |= TCP_CONN_RECOVERY
+#define tcp_recovery_off(tc) (tc)->flags &= ~TCP_CONN_RECOVERY
+#define tcp_in_fastrecovery(tc) ((tc)->flags & TCP_CONN_FAST_RECOVERY)
+#define tcp_in_recovery(tc) ((tc)->flags & (TCP_CONN_RECOVERY))
+#define tcp_in_slowstart(tc) (tc->cwnd < tc->ssthresh)
+#define tcp_disconnect_pending(tc) ((tc)->flags & TCP_CONN_DCNT_PENDING)
+#define tcp_disconnect_pending_on(tc) ((tc)->flags |= TCP_CONN_DCNT_PENDING)
+#define tcp_disconnect_pending_off(tc) ((tc)->flags &= ~TCP_CONN_DCNT_PENDING)
+#define tcp_fastrecovery_first(tc) ((tc)->flags & TCP_CONN_FRXT_FIRST)
+#define tcp_fastrecovery_first_on(tc) ((tc)->flags |= TCP_CONN_FRXT_FIRST)
+#define tcp_fastrecovery_first_off(tc) ((tc)->flags &= ~TCP_CONN_FRXT_FIRST)
+
+#define tcp_in_cong_recovery(tc) ((tc)->flags & 		\
+	  (TCP_CONN_FAST_RECOVERY | TCP_CONN_RECOVERY))
+
+always_inline void
+tcp_cong_recovery_off (tcp_connection_t * tc)
+{
+  tc->flags &= ~(TCP_CONN_FAST_RECOVERY | TCP_CONN_RECOVERY);
+  tcp_fastrecovery_first_off (tc);
+}
+
+#define tcp_csum_offload(tc) (!((tc)->cfg_flags & TCP_CFG_F_NO_CSUM_OFFLOAD))
+
+#define tcp_zero_rwnd_sent(tc) ((tc)->flags & TCP_CONN_ZERO_RWND_SENT)
+#define tcp_zero_rwnd_sent_on(tc) (tc)->flags |= TCP_CONN_ZERO_RWND_SENT
+#define tcp_zero_rwnd_sent_off(tc) (tc)->flags &= ~TCP_CONN_ZERO_RWND_SENT
+
+always_inline tcp_connection_t *
+tcp_get_connection_from_transport (transport_connection_t * tconn)
+{
+  return (tcp_connection_t *) tconn;
+}
+
+#endif /* SRC_VNET_TCP_TCP_TYPES_H_ */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */