Initial commit of vpp code.v1.0.0

Change-Id: Ib246f1fbfce93274020ee93ce461e3d8bd8b9f17
Signed-off-by: Ed Warnicke <eaw@cisco.com>

2 files changed, 1030 insertions, 0 deletions

diff --git a/vnet/example/main_stub.c b/vnet/example/main_stub.c
new file mode 100644
index 00000000000..c45932baa39
--- /dev/null
+++ b/vnet/example/main_stub.c
@@ -0,0 +1,203 @@
+/*
+ * Copyright (c) 2015 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 <vlib/vlib.h>
+#include <vlib/unix/unix.h>
+#include <vnet/pg/pg.h>
+#include <vnet/ethernet/ethernet.h>
+#include <vnet/ip/ip.h>
+#include <vnet/ip/tcp.h>
+
+#include <vlib/unix/cj.h>
+
+DECLARE_CJ_GLOBAL_LOG
+
+static clib_error_t *
+vnet_example_init (vlib_main_t * vm)
+{
+  clib_error_t * error = 0;
+
+  /* Due to crude comment-out of eliot's smp stuff */
+  vm->heap_size = 256<<20;
+
+  if ((error = vlib_call_init_function (vm, pg_init)))
+    return error;
+  if ((error = vlib_call_init_function (vm, ip_main_init)))
+    return error;
+  if ((error = vlib_call_init_function (vm, ethernet_init)))
+    return error;
+  if ((error = vlib_call_init_function (vm, ethernet_arp_init)))
+    return error;
+  if ((error = vlib_call_init_function (vm, osi_init)))
+    return error;
+  if ((error = vlib_call_init_function (vm, srp_init)))
+    return error;
+#if DPDK == 0
+  if ((error = vlib_call_init_function (vm, ixge_init)))
+    return error;
+  if ((error = vlib_call_init_function (vm, ixgev_init)))
+    return error;
+  if ((error = vlib_call_init_function (vm, ige_init)))
+    return error;
+#else
+  if ((error = vlib_call_init_function (vm, dpdk_init)))
+    return error;
+#endif
+  
+  if ((error = vlib_call_init_function (vm, dhcp_proxy_init)))
+    return error;
+  if ((error = vlib_call_init_function (vm, mpls_init)))
+    return error;
+  if ((error = vlib_call_init_function (vm, mpls_interface_init)))
+    return error;
+
+  if ((error = vlib_call_init_function (vm, l2_init)))
+    return error;
+  if ((error = vlib_call_init_function (vm, l2tp_init)))
+    return error;
+
+  if ((error = unix_physmem_init (vm, /* physical_memory_required */ 0)))
+    return error;
+
+  if ((error = unix_physmem_init (vm, /* physical_memory_required */ 0)))
+    return error;
+
+  if ((error = vlib_call_init_function (vm, tuntap_init)))
+    return error;
+
+  vlib_unix_cli_set_prompt ("VNET: ");
+
+  return error;
+}
+
+VLIB_INIT_FUNCTION (vnet_example_init);
+
+int main (int argc, char * argv[])
+{
+  clib_mem_init (0, (2ULL << 30));
+  return vlib_unix_main (argc, argv);
+}
+
+#if 0
+#define foreach_tcp_test_error			\
+  _ (SEGMENTS_RECEIVED, "segments received")
+
+typedef enum {
+#define _(sym,str) TCP_TEST_ERROR_##sym,
+  foreach_tcp_test_error
+#undef _
+  TCP_TEST_N_ERROR,
+} tcp_test_error_t;
+
+static char * tcp_test_error_strings[] = {
+#define _(sym,string) string,
+  foreach_tcp_test_error
+#undef _
+};
+
+static uword
+tcp_test (vlib_main_t * vm,
+	  vlib_node_runtime_t * node,
+	  vlib_frame_t * frame)
+{
+  uword n_packets = frame->n_vectors;
+  u32 * from, * to_next;
+  u32 n_left_from, n_left_to_next, next;
+
+  from = vlib_frame_vector_args (frame);
+  n_left_from = n_packets;
+  next = node->cached_next_index;
+  
+  while (n_left_from > 0)
+    {
+      vlib_get_next_frame (vm, node, next, to_next, n_left_to_next);
+
+      while (n_left_from > 0 && n_left_to_next > 0)
+	{
+	  vlib_buffer_t * p0;
+	  u32 bi0;
+	  u8 error0, next0;
+      
+	  bi0 = to_next[0] = from[0];
+
+	  from += 1;
+	  n_left_from -= 1;
+	  to_next += 1;
+	  n_left_to_next -= 1;
+      
+	  p0 = vlib_get_buffer (vm, bi0);
+
+	  clib_warning ("got '%U'", format_vlib_buffer_contents, vm, p0);
+
+	  error0 = next0 = 0;
+	  p0->error = node->errors[error0];
+
+	  if (PREDICT_FALSE (next0 != next))
+	    {
+	      to_next -= 1;
+	      n_left_to_next += 1;
+
+	      vlib_put_next_frame (vm, node, next, n_left_to_next);
+
+	      next = next0;
+	      vlib_get_next_frame (vm, node, next, to_next, n_left_to_next);
+	      to_next[0] = bi0;
+	      to_next += 1;
+	      n_left_to_next -= 1;
+	    }
+	}
+  
+      vlib_put_next_frame (vm, node, next, n_left_to_next);
+    }
+
+  return frame->n_vectors;
+}
+
+VLIB_REGISTER_NODE (tcp_test_node) = {
+  .function = tcp_test,
+  .name = "tcp-test",
+
+  .vector_size = sizeof (u32),
+
+  .n_next_nodes = 1,
+  .next_nodes = {
+    [0] = "error-drop",
+  },
+
+  .n_errors = TCP_TEST_N_ERROR,
+  .error_strings = tcp_test_error_strings,
+};
+
+static clib_error_t *
+tcp_test_init (vlib_main_t * vm)
+{
+  clib_error_t * error = 0;
+
+  {
+    tcp_listener_registration_t r = {
+      .port = 1234,
+      .flags = TCP_LISTENER_IP4,
+      .data_node_index = tcp_test_node.index,
+      .event_function = 0,
+    };
+
+    tcp_register_listener (vm, &r);
+  }
+
+  return error;
+}
+
+VLIB_INIT_FUNCTION (tcp_test_init);
+
+#endif
diff --git a/vnet/example/rtt_test.c b/vnet/example/rtt_test.c
new file mode 100644
index 00000000000..98f0cdf2f6b
--- /dev/null
+++ b/vnet/example/rtt_test.c
@@ -0,0 +1,827 @@
+/*
+ * Copyright (c) 2015 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/ip/ip.h>
+#include <math.h>
+
+/* 20 byte TCP + 12 bytes of options (timestamps) = 32 bytes */
+typedef struct {
+  u64 sequence_number;
+  f64 time_stamp;
+  u32 stream_index;
+  u32 unused[3];
+} __attribute__ ((packed)) rtt_test_header_t;
+
+typedef struct {
+  ip4_header_t ip4;
+  rtt_test_header_t rtt;
+  u8 payload[0];
+} __attribute__ ((packed)) rtt_test_packet_t;
+
+typedef struct {
+  ip4_address_t src_address, dst_address;
+
+  f64 n_packets_to_send;
+
+  f64 send_rate_bits_per_second;
+  f64 send_rate_packets_per_second;
+
+  f64 packet_accumulator;
+
+  u64 n_packets_sent;
+
+  /* [0] from past, [1] in sequence, [2] from future. */
+  u64 n_packets_received[3];
+
+  f64 tx_time_stream_created;
+  f64 tx_time_last_sent;
+
+  f64 rx_ack_times[2];
+
+  u64 rx_expected_sequence_number;
+
+  u32 n_bytes_payload;
+
+  /* Including IP & L2 header. */
+  u32 n_bytes_per_packet_on_wire;
+
+  f64 ave_rtt, rms_rtt, rtt_count;
+
+  u32 max_n_rx_ack_dts;
+  f64 * rx_ack_dts;
+
+  u32 * rtt_histogram;
+
+  vlib_packet_template_t packet_template;
+} rtt_test_stream_t;
+
+typedef struct {
+  /* Size of encapsulation (e.g. 14 for ethernet). */
+  u32 n_encap_bytes;
+
+  u32 is_sender;
+
+  u32 verbose;
+
+  f64 rms_histogram_units;
+
+  rtt_test_stream_t stream_history[32];
+  u32 stream_history_index;
+
+  rtt_test_stream_t * stream_pool;
+
+  vlib_packet_template_t ack_packet_template;
+  u16 ack_packet_template_ip4_checksum;
+} rtt_test_main_t;
+
+/* Use 2 IP protocols 253/254 which are assigned for experimental testing. */
+typedef enum {
+  RTT_TEST_IP_PROTOCOL_DATA = 253,
+  RTT_TEST_IP_PROTOCOL_ACK = 254,
+} rtt_test_ip_protcol_t;
+
+always_inline void
+rtt_test_stream_free (vlib_main_t * vm, rtt_test_main_t * tm, rtt_test_stream_t * s)
+{
+  vlib_packet_template_free (vm, &s->packet_template);
+  memset (&s->packet_template, 0, sizeof (s->packet_template));
+
+  tm->stream_history[tm->stream_history_index++] = s[0];
+  if (tm->stream_history_index >= ARRAY_LEN (tm->stream_history))
+    tm->stream_history_index = 0;
+
+  s->rtt_histogram = 0;
+  pool_put (tm->stream_pool, s);
+}
+
+rtt_test_main_t rtt_test_main;
+
+#define foreach_rtt_test_error				\
+  _ (packets_received, "packets received")		\
+  _ (listener_acks_dropped, "listener acks dropped")	\
+  _ (unknown_stream, "unknown stream")
+
+typedef enum {
+#define _(sym,str) RTT_TEST_ERROR_##sym,
+  foreach_rtt_test_error
+#undef _
+  RTT_TEST_N_ERROR,
+} rtt_test_error_t;
+
+static char * rtt_test_error_strings[] = {
+#define _(sym,string) string,
+  foreach_rtt_test_error
+#undef _
+};
+
+typedef enum {
+  RTT_TEST_RX_NEXT_DROP,
+  RTT_TEST_RX_NEXT_ECHO,
+  RTT_TEST_RX_N_NEXT,
+} rtt_test_rx_next_t;
+
+static uword
+rtt_test_rx_data (vlib_main_t * vm,
+		  vlib_node_runtime_t * node,
+		  vlib_frame_t * frame)
+{
+  rtt_test_main_t * tm = &rtt_test_main;
+  uword n_packets = frame->n_vectors;
+  u32 * from, * to_drop, * to_echo;
+  u32 n_left_from, n_left_to_drop, n_left_to_echo;
+
+  from = vlib_frame_vector_args (frame);
+  n_left_from = n_packets;
+  
+  while (n_left_from > 0)
+    {
+      vlib_get_next_frame (vm, node, RTT_TEST_RX_NEXT_DROP, to_drop, n_left_to_drop);
+      vlib_get_next_frame (vm, node, RTT_TEST_RX_NEXT_ECHO, to_echo, n_left_to_echo);
+
+      while (n_left_from > 0 && n_left_to_drop > 0 && n_left_to_echo > 0)
+	{
+	  vlib_buffer_t * p0;
+	  ip4_header_t * ip0;
+	  rtt_test_header_t * r0;
+	  rtt_test_packet_t * ack0;
+	  ip_csum_t sum0;
+	  u32 bi0;
+      
+	  bi0 = to_drop[0] = from[0];
+
+	  from += 1;
+	  n_left_from -= 1;
+	  to_drop += 1;
+	  n_left_to_drop -= 1;
+      
+	  p0 = vlib_get_buffer (vm, bi0);
+	  ip0 = vlib_buffer_get_current (p0);
+
+	  r0 = ip4_next_header (ip0);
+
+	  p0->error = node->errors[RTT_TEST_ERROR_listener_acks_dropped];
+
+	  ack0 = vlib_packet_template_get_packet (vm, &tm->ack_packet_template, to_echo);
+
+	  to_echo += 1;
+	  n_left_to_echo -= 1;
+
+	  sum0 = tm->ack_packet_template_ip4_checksum;
+
+	  ack0->ip4.src_address = ip0->dst_address;
+	  sum0 = ip_csum_add_even (sum0, ack0->ip4.src_address.as_u32);
+
+	  ack0->ip4.dst_address = ip0->src_address;
+	  sum0 = ip_csum_add_even (sum0, ack0->ip4.dst_address.as_u32);
+
+	  ack0->ip4.checksum = ip_csum_fold (sum0);
+
+	  ASSERT (ack0->ip4.checksum == ip4_header_checksum (&ack0->ip4));
+
+	  ack0->rtt = r0[0];
+	}
+  
+      vlib_put_next_frame (vm, node, RTT_TEST_RX_NEXT_DROP, n_left_to_drop);
+      vlib_put_next_frame (vm, node, RTT_TEST_RX_NEXT_ECHO, n_left_to_echo);
+    }
+
+  return frame->n_vectors;
+}
+
+VLIB_REGISTER_NODE (rtt_test_rx_data_node) = {
+  .function = rtt_test_rx_data,
+  .name = "rtt-test-rx-data",
+
+  .vector_size = sizeof (u32),
+
+  .n_next_nodes = RTT_TEST_RX_N_NEXT,
+  .next_nodes = {
+    [RTT_TEST_RX_NEXT_DROP] = "error-drop",
+    [RTT_TEST_RX_NEXT_ECHO] = "ip4-input-no-checksum",
+  },
+
+  .n_errors = RTT_TEST_N_ERROR,
+  .error_strings = rtt_test_error_strings,
+};
+
+static uword
+rtt_test_rx_ack (vlib_main_t * vm,
+		 vlib_node_runtime_t * node,
+		 vlib_frame_t * frame)
+{
+  rtt_test_main_t * tm = &rtt_test_main;
+  uword n_packets = frame->n_vectors;
+  u32 * from, * to_drop;
+  u32 n_left_from, n_left_to_drop;
+  f64 now = vlib_time_now (vm);
+  vlib_node_runtime_t * error_node = vlib_node_get_runtime (vm, rtt_test_rx_data_node.index);
+
+  from = vlib_frame_vector_args (frame);
+  n_left_from = n_packets;
+  
+  while (n_left_from > 0)
+    {
+      vlib_get_next_frame (vm, node, RTT_TEST_RX_NEXT_DROP, to_drop, n_left_to_drop);
+
+      while (n_left_from > 0 && n_left_to_drop > 0)
+	{
+	  vlib_buffer_t * p0;
+	  ip4_header_t * ip0;
+	  rtt_test_header_t * r0;
+	  rtt_test_stream_t * s0;
+	  u32 bi0, i0;
+	  u64 rseq0, eseq0;
+      
+	  i0 = 0;
+	  bi0 = to_drop[0] = from[0];
+
+	  from += 1;
+	  n_left_from -= 1;
+	  to_drop += 1;
+	  n_left_to_drop -= 1;
+      
+	  p0 = vlib_get_buffer (vm, bi0);
+	  ip0 = vlib_buffer_get_current (p0);
+
+	  r0 = ip4_next_header (ip0);
+
+	  p0->error = error_node->errors[RTT_TEST_ERROR_listener_acks_dropped];
+
+	  if (pool_is_free_index (tm->stream_pool, r0->stream_index))
+	    goto bad_stream_x1;
+
+	  s0 = pool_elt_at_index (tm->stream_pool, r0->stream_index);
+
+	  rseq0 = r0->sequence_number;
+	  eseq0 = s0->rx_expected_sequence_number;
+
+	  if (rseq0 != eseq0)
+	    goto out_of_sequence_x1;
+
+	  s0->rx_expected_sequence_number = rseq0 + 1;
+	  s0->n_packets_received[1] += 1;
+	  
+	  vec_add1 (s0->rx_ack_dts, now - r0->time_stamp);
+	  _vec_len (s0->rx_ack_dts) -= _vec_len (s0->rx_ack_dts) >= s0->max_n_rx_ack_dts;
+
+	  i0 = rseq0 != 0;
+	  s0->rx_ack_times[i0] = now;
+	  continue;
+
+	bad_stream_x1:
+	  {
+	    ELOG_TYPE_DECLARE (e) = {
+	      .format = "rtt-test: unknown stream %d",
+	      .format_args = "i4",
+	    };
+	    struct { u32 stream; } * ed;
+	    ed = ELOG_DATA (&vm->elog_main, e);
+	    ed->stream = r0->stream_index;
+	  }
+	  continue;
+
+	out_of_sequence_x1:
+	  i0 = (r0->sequence_number < s0->rx_expected_sequence_number
+		? 0
+		: (i0 ? 1 : 2));
+	  if (i0 != 1)
+	    {
+	      ELOG_TYPE_DECLARE (e) = {
+		.format = "rtt-test: out-of-seq expected %Ld got %Ld",
+		.format_args = "i8i8",
+	      };
+	      struct { u64 expected, got; } * ed;
+	      ed = ELOG_DATA (&vm->elog_main, e);
+	      ed->expected = s0->rx_expected_sequence_number;
+	      ed->got = r0->sequence_number;
+	    }
+
+	  s0->rx_expected_sequence_number = i0 > 0 ? r0->sequence_number + 1 : s0->rx_expected_sequence_number;
+
+	  s0->n_packets_received[i0] += 1;
+
+	  i0 = r0->sequence_number > 0;
+	  s0->rx_ack_times[i0] = now;
+	}
+  
+      vlib_put_next_frame (vm, node, RTT_TEST_RX_NEXT_DROP, n_left_to_drop);
+    }
+
+  return frame->n_vectors;
+}
+
+VLIB_REGISTER_NODE (rtt_test_rx_ack_node) = {
+  .function = rtt_test_rx_ack,
+  .name = "rtt-test-rx-ack",
+
+  .vector_size = sizeof (u32),
+
+  .n_next_nodes = RTT_TEST_RX_N_NEXT,
+  .next_nodes = {
+    [RTT_TEST_RX_NEXT_DROP] = "error-drop",
+    [RTT_TEST_RX_NEXT_ECHO] = "ip4-input-no-checksum",
+  },
+};
+
+always_inline void
+rtt_test_tx_packets (vlib_main_t * vm,
+		     vlib_node_runtime_t * node,
+		     rtt_test_stream_t * s,
+		     f64 time_now,
+		     uword n_packets_to_send)
+{
+  u32 * to_next, n_this_frame, n_left, n_trace, next, i;
+  rtt_test_packet_t * p;
+  vlib_buffer_t * b;
+
+  next = 0;
+  while (n_packets_to_send > 0)
+    {
+      vlib_get_next_frame (vm, node, next, to_next, n_left);
+
+      n_this_frame = clib_min (n_packets_to_send, n_left);
+
+      for (i = 0; i < n_this_frame; i++)
+	{
+	  p = vlib_packet_template_get_packet (vm, &s->packet_template, to_next + i);
+	  p->rtt.time_stamp = time_now;
+	  p->rtt.sequence_number = s->n_packets_sent + i;
+	}
+
+      n_trace = vlib_get_trace_count (vm, node);
+      if (n_trace > 0)
+	{
+	  u32 n = clib_min (n_trace, n_this_frame);
+
+	  vlib_set_trace_count (vm, node, n_trace - n);
+	  for (i = 0; i < n_this_frame; i++)
+	    {
+	      b = vlib_get_buffer (vm, to_next[i]);
+	      vlib_trace_buffer (vm, node, next, b, /* follow_chain */ 1);
+	    }
+	}
+
+      s->n_packets_sent += n_this_frame;
+      n_packets_to_send -= n_this_frame;
+      n_left -= n_this_frame;
+
+      vlib_put_next_frame (vm, node, next, n_left);
+    }
+}
+
+always_inline uword
+rtt_test_stream_is_done (rtt_test_stream_t * s, f64 time_now)
+{
+  /* Need to send more packets? */
+  if (s->n_packets_to_send > 0 && s->n_packets_sent < s->n_packets_to_send)
+    return 0;
+
+  /* Received everything we've sent? */
+  if (s->n_packets_received[0] + s->n_packets_received[1] + s->n_packets_received[2] >= s->n_packets_to_send)
+    return 1;
+
+  /* No ACK received after 5 seconds of sending. */
+  if (s->rx_ack_times[0] == 0
+      && s->n_packets_sent > 0
+      && time_now - s->tx_time_stream_created > 5)
+    return 1;
+
+  /* No ACK received after 5 seconds of waiting? */
+  if (time_now - s->rx_ack_times[1] > 5)
+    return 1;
+
+  return 0;
+}
+
+static_always_inline uword
+rtt_test_tx_stream (vlib_main_t * vm,
+		    vlib_node_runtime_t * node,
+		    rtt_test_stream_t * s)
+{
+  rtt_test_main_t * tm = &rtt_test_main;
+  uword n_packets;
+  f64 time_now, dt;
+
+  time_now = vlib_time_now (vm);
+
+  if (rtt_test_stream_is_done (s, time_now))
+    {
+      {
+	ELOG_TYPE_DECLARE (e) = {
+	  .format = "rtt-test: done stream %d",
+	  .format_args = "i4",
+	};
+	struct { u32 stream_index; } * ed;
+	ed = ELOG_DATA (&vm->elog_main, e);
+	ed->stream_index = s - tm->stream_pool;
+      }
+
+      rtt_test_stream_free (vm, tm, s);
+      if (pool_elts (tm->stream_pool) == 0)
+	vlib_node_set_state (vm, node->node_index, VLIB_NODE_STATE_DISABLED);
+      return 0;
+    }
+
+  /* Apply rate limit. */
+  dt = time_now - s->tx_time_last_sent;
+  s->tx_time_last_sent = time_now;
+
+  n_packets = VLIB_FRAME_SIZE;
+  if (s->send_rate_packets_per_second > 0)
+    {
+      s->packet_accumulator += dt * s->send_rate_packets_per_second;
+      n_packets = s->packet_accumulator;
+
+      /* Never allow accumulator to grow if we get behind. */
+      s->packet_accumulator -= n_packets;
+    }
+
+  /* Apply fixed limit. */
+  if (s->n_packets_to_send > 0
+      && s->n_packets_sent + n_packets > s->n_packets_to_send)
+    n_packets = s->n_packets_to_send - s->n_packets_sent;
+
+  /* Generate up to one frame's worth of packets. */
+  if (n_packets > VLIB_FRAME_SIZE)
+    n_packets = VLIB_FRAME_SIZE;
+
+  if (n_packets > 0)
+    rtt_test_tx_packets (vm, node, s, time_now, n_packets);
+
+  return n_packets;
+}
+
+static uword
+rtt_test_tx (vlib_main_t * vm,
+	     vlib_node_runtime_t * node,
+	     vlib_frame_t * frame)
+{
+  rtt_test_main_t * tm = &rtt_test_main;
+  rtt_test_stream_t * s;
+  uword n_packets = 0;
+
+  pool_foreach (s, tm->stream_pool, ({
+    n_packets += rtt_test_tx_stream (vm, node, s);
+  }));
+
+  return n_packets;
+}
+
+VLIB_REGISTER_NODE (rtt_test_tx_node) = {
+  .function = rtt_test_tx,
+  .name = "rtt-test-tx",
+  .type = VLIB_NODE_TYPE_INPUT,
+  .state = VLIB_NODE_STATE_DISABLED,
+
+  .vector_size = sizeof (u32),
+
+  .n_next_nodes = 1,
+  .next_nodes = {
+    [0] = "ip4-input-no-checksum",
+  },
+};
+
+static void rtt_test_stream_compute (rtt_test_main_t * tm, rtt_test_stream_t * s)
+{
+  int i;
+
+  /* Compute average and standard deviation of RTT time. */
+  if (vec_len (s->rx_ack_dts) == 0)
+    return;
+
+  {
+    f64 c = vec_len (s->rx_ack_dts);
+
+    s->ave_rtt = s->rms_rtt = 0;
+    vec_foreach_index (i, s->rx_ack_dts)
+      {
+	f64 dt = s->rx_ack_dts[i];
+	s->ave_rtt += dt;
+	s->rms_rtt += dt*dt;
+      }
+    s->ave_rtt /= c;
+    s->rms_rtt = sqrt (s->rms_rtt / c - s->ave_rtt*s->ave_rtt);
+    s->rtt_count = c;
+  }
+
+  if (! tm->rms_histogram_units)
+    tm->rms_histogram_units = .1;
+
+  /* Generate historgram. */
+  vec_foreach_index (i, s->rx_ack_dts)
+    {
+      i32 bin = flt_round_nearest ((s->rx_ack_dts[i] - s->ave_rtt) / (tm->rms_histogram_units * s->rms_rtt));
+      u32 ib = bin < 0 ? 2*(-bin) + 1 : 2 *bin;
+      vec_validate (s->rtt_histogram, ib);
+      s->rtt_histogram[ib] += 1;
+    }  
+
+  if (s->n_packets_sent >= s->n_packets_to_send)
+    vec_free (s->rx_ack_dts);
+}
+
+static clib_error_t *
+do_plot_stream (rtt_test_main_t * tm, rtt_test_stream_t * s, char * file_name, int n)
+{
+  FILE * out;
+  char * f;
+  clib_error_t * error = 0;
+  u32 i;
+
+  f = (char *) format (0, "%s.%d%c", file_name, n, 0);
+  out = fopen (f, "w");
+
+  if (! out)
+    {
+      error = clib_error_return_unix (0, "open `%s'", f);
+      goto done;
+    }
+
+  rtt_test_stream_compute (tm, s);
+  vec_foreach_index (i, s->rtt_histogram)
+    {
+      if (s->rtt_histogram[i] > 0)
+	{
+	  i32 bi = (i & 1) ? -(i/2) : (i/2);
+	  f64 dt = s->ave_rtt + (bi * tm->rms_histogram_units * s->rms_rtt);
+	  fformat (out, "%.6e %.6e\n",
+		   dt, s->rtt_histogram[i] / s->rtt_count);
+	}
+    }
+  clib_warning ("wrote `%s'", f);
+
+ done:
+  vec_free (f);
+  fclose (out);
+  return error;
+}
+
+static clib_error_t *
+do_plot (rtt_test_main_t * tm, char * file_name)
+{
+  rtt_test_stream_t * s;
+  clib_error_t * error = 0;
+  int i, n;
+
+  n = 0;
+  for (i = 0; i < ARRAY_LEN (tm->stream_history); i++)
+    {
+      s = tm->stream_history + i;
+      if (s->n_packets_sent > 0)
+	{
+	  error = do_plot_stream (tm, s, file_name, n++);
+	  if (error)
+	    return error;
+	}
+    }
+
+  pool_foreach (s, tm->stream_pool, ({
+    error = do_plot_stream (tm, s, file_name, n++);
+    if (error)
+      return error;
+  }));
+
+  return error;
+}
+
+static clib_error_t *
+rtt_test_command (vlib_main_t * vm,
+		  unformat_input_t * input,
+		  vlib_cli_command_t * cmd)
+{
+  rtt_test_main_t * tm = &rtt_test_main;
+  rtt_test_stream_t * s;
+
+  {
+    char * file_name;
+
+    if (unformat (input, "plot %s", &file_name))
+      {
+	clib_error_t * e = do_plot (tm, file_name);
+	vec_free (file_name);
+	return e;
+      }
+  }
+
+  pool_get (tm->stream_pool, s);
+
+  memset (s, 0, sizeof (s[0]));
+  s->n_packets_to_send = 1;
+  s->send_rate_bits_per_second = 1e6;
+  s->n_bytes_payload = 1448;
+  s->max_n_rx_ack_dts = 0;
+  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (input, "%U -> %U",
+		    unformat_ip4_address, &s->src_address,
+		    unformat_ip4_address, &s->dst_address))
+	;
+      else if (unformat (input, "count %f", &s->n_packets_to_send))
+	;
+      else if (unformat (input, "hist %d", &s->max_n_rx_ack_dts))
+	;
+      else if (unformat (input, "rate %f", &s->send_rate_bits_per_second))
+	;
+      else if (unformat (input, "size %d", &s->n_bytes_payload))
+	;
+      else
+	return clib_error_return (0, "parse error: %U", format_unformat_error, input);
+    }
+
+  if (pool_elts (tm->stream_pool) == 1)
+    vlib_node_set_state (vm, rtt_test_tx_node.index, VLIB_NODE_STATE_POLLING);
+
+  if (! s->max_n_rx_ack_dts)
+    s->max_n_rx_ack_dts = s->n_packets_to_send;
+  vec_validate (s->rx_ack_dts, s->max_n_rx_ack_dts - 1);
+  _vec_len (s->rx_ack_dts) = 0;
+
+  s->tx_time_stream_created = vlib_time_now (vm);
+  s->tx_time_last_sent = s->tx_time_stream_created;
+  s->n_bytes_per_packet_on_wire
+    = (s->n_bytes_payload
+       + sizeof (rtt_test_header_t)
+       + sizeof (ip4_header_t)
+       + tm->n_encap_bytes);
+
+  s->send_rate_packets_per_second = s->send_rate_bits_per_second / (s->n_bytes_per_packet_on_wire * BITS (u8));
+
+  {
+    rtt_test_packet_t * t;
+    int i;
+
+    t = clib_mem_alloc_no_fail (sizeof (t[0]) + s->n_bytes_payload);
+    memset (t, 0, sizeof (t[0]));
+
+    t->ip4.ip_version_and_header_length = 0x45;
+    t->ip4.length = clib_host_to_net_u16 (sizeof (t[0]) + s->n_bytes_payload);
+    t->ip4.flags_and_fragment_offset = clib_host_to_net_u16 (IP4_HEADER_FLAG_DONT_FRAGMENT);
+    t->ip4.protocol = RTT_TEST_IP_PROTOCOL_DATA;
+    t->ip4.ttl = 64;
+
+    t->ip4.src_address = s->src_address;
+    t->ip4.dst_address = s->dst_address;
+    
+    t->ip4.checksum = ip4_header_checksum (&t->ip4);
+
+    t->rtt.stream_index = s - tm->stream_pool;
+
+    for (i = 0; i < s->n_bytes_payload; i++)
+      t->payload[i] = i;
+
+    vlib_packet_template_init (vm, &s->packet_template,
+			       t, sizeof (t[0]) + s->n_bytes_payload,
+			       /* alloc chunk size */ VLIB_FRAME_SIZE,
+			       "rtt-test stream %d data", s - tm->stream_pool);
+
+    clib_mem_free (t);
+  }
+
+  {
+    ELOG_TYPE_DECLARE (e) = {
+      .format = "rtt-test: start stream %d",
+      .format_args = "i4",
+    };
+    struct { u32 stream_index; } * ed;
+    ed = ELOG_DATA (&vm->elog_main, e);
+    ed->stream_index = s - tm->stream_pool;
+  }
+
+  return 0;
+}
+
+VLIB_CLI_COMMAND (rtt_test_cli_command, static) = {
+  .path = "test rtt",
+  .short_help = "Measure RTT test protocol",
+  .function = rtt_test_command,
+};
+
+static u8 * format_rtt_test_stream (u8 * s, va_list * args)
+{
+  rtt_test_stream_t * t = va_arg (*args, rtt_test_stream_t *);
+  uword indent = format_get_indent (s);
+
+  s = format (s, "%U -> %U",
+	      format_ip4_address, &t->src_address,
+	      format_ip4_address, &t->dst_address);
+
+  s = format (s, "\n%U  sent %Ld, received: from-past %Ld in-sequence %Ld from-future %Ld",
+	      format_white_space, indent,
+	      t->n_packets_sent,
+	      t->n_packets_received[0], t->n_packets_received[1], t->n_packets_received[2]);
+
+  s = format (s, "\n%U  rx-rate %.4e bits/sec",
+	      format_white_space, indent,
+	      (((f64) (t->n_packets_received[0] + t->n_packets_received[1] + t->n_packets_received[2]) * (f64) t->n_bytes_per_packet_on_wire * BITS (u8))
+	       / (t->rx_ack_times[1] - t->rx_ack_times[0])));
+	       
+  rtt_test_stream_compute (&rtt_test_main, t);
+
+  s = format (s, "\n%U  rtt %.4e +- %.4e",
+	      format_white_space, indent,
+	      t->ave_rtt, t->rms_rtt);
+
+  return s;
+}
+
+static clib_error_t *
+rtt_show_command (vlib_main_t * vm,
+		  unformat_input_t * input,
+		  vlib_cli_command_t * cmd)
+{
+  rtt_test_main_t * tm = &rtt_test_main;
+  rtt_test_stream_t * s;
+  int i;
+
+  for (i = 0; i < ARRAY_LEN (tm->stream_history); i++)
+    {
+      s = tm->stream_history + i;
+      if (s->n_packets_sent > 0)
+	vlib_cli_output (vm, "%U", format_rtt_test_stream, s);
+    }
+
+  pool_foreach (s, tm->stream_pool, ({
+    vlib_cli_output (vm, "%U", format_rtt_test_stream, s);
+  }));
+
+  return 0;
+}
+
+VLIB_CLI_COMMAND (rtt_show_cli_command, static) = {
+  .path = "show rtt",
+  .short_help = "Show RTT measurements",
+  .function = rtt_show_command,
+};
+
+static clib_error_t *
+rtt_test_init (vlib_main_t * vm)
+{
+  rtt_test_main_t * tm = &rtt_test_main;
+
+  ip4_register_protocol (RTT_TEST_IP_PROTOCOL_DATA, rtt_test_rx_data_node.index);
+  ip4_register_protocol (RTT_TEST_IP_PROTOCOL_ACK, rtt_test_rx_ack_node.index);
+
+  {
+    rtt_test_packet_t ack;
+
+    memset (&ack, 0, sizeof (ack));
+
+    ack.ip4.ip_version_and_header_length = 0x45;
+    ack.ip4.length = clib_host_to_net_u16 (sizeof (ack));
+    ack.ip4.flags_and_fragment_offset = clib_host_to_net_u16 (IP4_HEADER_FLAG_DONT_FRAGMENT);
+    ack.ip4.protocol = RTT_TEST_IP_PROTOCOL_ACK;
+    ack.ip4.ttl = 64;
+
+    ack.ip4.checksum = ip4_header_checksum (&ack.ip4);
+    tm->ack_packet_template_ip4_checksum = ack.ip4.checksum;
+
+    vlib_packet_template_init (vm, &tm->ack_packet_template,
+			       &ack,
+			       sizeof (ack),
+			       /* alloc chunk size */ VLIB_FRAME_SIZE,
+			       "rtt-test ack");
+  }
+
+  return /* no error */ 0;
+}
+
+static VLIB_INIT_FUNCTION (rtt_test_init);
+
+static clib_error_t *
+rtt_test_config (vlib_main_t * vm, unformat_input_t * input)
+{
+  rtt_test_main_t * tm = &rtt_test_main;
+  clib_error_t * error = 0;
+
+  tm->rms_histogram_units = .1;
+  tm->n_encap_bytes = 
+    (14 /* ethernet header */
+     + 8 /* preamble */
+     + 12 /* inter packet gap */
+     + 4 /* crc */);
+  tm->verbose = 1;
+  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
+    {
+      if (unformat (input, "rms-histogram-units %f", &tm->rms_histogram_units))
+	;
+      else if (unformat (input, "silent"))
+	tm->verbose = 0;
+      else
+	clib_error ("%U", format_unformat_error, input);
+    }
+
+  return error;
+}
+
+VLIB_CONFIG_FUNCTION (rtt_test_config, "rtt-test");