nat: use SVR

Remove NAT's implementation of shallow virtual reassembly with
corresponding CLIs, APIs & tests. Replace with standalone shallow
virtual reassembly provided by ipX-sv-reass* nodes.

Type: refactor
Change-Id: I7e6c7487a5a500d591f6871474a359e0993e59b6
Signed-off-by: Klement Sekera <ksekera@cisco.com>

7 files changed, 413 insertions, 512 deletions

diff --git a/src/vnet/ip/ip4_packet.h b/src/vnet/ip/ip4_packet.h
index 79cf22c4d70..1d3607ea34c 100644
--- a/src/vnet/ip/ip4_packet.h
+++ b/src/vnet/ip/ip4_packet.h
@@ -196,13 +196,13 @@ typedef union
 
 #define IP4_ROUTER_ALERT_OPTION 20
 
-always_inline int
+always_inline u16
 ip4_get_fragment_offset (const ip4_header_t * i)
 {
   return clib_net_to_host_u16 (i->flags_and_fragment_offset) & 0x1fff;
 }
 
-always_inline int
+always_inline u16
 ip4_get_fragment_more (const ip4_header_t * i)
 {
   return clib_net_to_host_u16 (i->flags_and_fragment_offset) &
diff --git a/src/vnet/ip/ip4_to_ip6.h b/src/vnet/ip/ip4_to_ip6.h
index b1905e4154b..21538a90e44 100644
--- a/src/vnet/ip/ip4_to_ip6.h
+++ b/src/vnet/ip/ip4_to_ip6.h
@@ -25,8 +25,8 @@
 /**
  * IPv4 to IPv6 set call back function type
  */
-typedef int (*ip4_to_ip6_set_fn_t) (ip4_header_t * ip4, ip6_header_t * ip6,
-				    void *ctx);
+typedef int (*ip4_to_ip6_set_fn_t) (vlib_buffer_t * b, ip4_header_t * ip4,
+				    ip6_header_t * ip6, void *ctx);
 
 /* *INDENT-OFF* */
 static u8 icmp_to_icmp6_updater_pointer_table[] =
@@ -261,7 +261,7 @@ icmp_to_icmp6 (vlib_buffer_t * p, ip4_to_ip6_set_fn_t fn, void *ctx,
 			       sizeof (*inner_frag));
 	  ip6 = vlib_buffer_get_current (p);
 	  memmove (u8_ptr_add (ip6, sizeof (*ip6) - sizeof (*ip4)), ip4,
-                   20 + 8);
+		   20 + 8);
 	  ip4 =
 	    (ip4_header_t *) u8_ptr_add (ip6, sizeof (*ip6) - sizeof (*ip4));
 	  icmp = (icmp46_header_t *) (ip4 + 1);
@@ -287,7 +287,7 @@ icmp_to_icmp6 (vlib_buffer_t * p, ip4_to_ip6_set_fn_t fn, void *ctx,
 	  vlib_buffer_advance (p, -2 * (sizeof (*ip6) - sizeof (*ip4)));
 	  ip6 = vlib_buffer_get_current (p);
 	  memmove (u8_ptr_add (ip6, sizeof (*ip6) - sizeof (*ip4)), ip4,
-                   20 + 8);
+		   20 + 8);
 	  ip4 =
 	    (ip4_header_t *) u8_ptr_add (ip6, sizeof (*ip6) - sizeof (*ip4));
 	  icmp = (icmp46_header_t *) u8_ptr_add (ip4, sizeof (*ip4));
@@ -340,7 +340,7 @@ icmp_to_icmp6 (vlib_buffer_t * p, ip4_to_ip6_set_fn_t fn, void *ctx,
       inner_ip6->hop_limit = inner_ip4->ttl;
       inner_ip6->protocol = inner_ip4->protocol;
 
-      if ((rv = inner_fn (inner_ip4, inner_ip6, inner_ctx)) != 0)
+      if ((rv = inner_fn (p, inner_ip4, inner_ip6, inner_ctx)) != 0)
 	return rv;
 
       if (PREDICT_FALSE (inner_frag != NULL))
@@ -411,7 +411,7 @@ icmp_to_icmp6 (vlib_buffer_t * p, ip4_to_ip6_set_fn_t fn, void *ctx,
   ip6->hop_limit = ip4->ttl;
   ip6->protocol = IP_PROTOCOL_ICMP6;
 
-  if ((rv = fn (ip4, ip6, ctx)) != 0)
+  if ((rv = fn (p, ip4, ip6, ctx)) != 0)
     return rv;
 
   //Truncate when the packet exceeds the minimal IPv6 MTU
@@ -437,217 +437,4 @@ icmp_to_icmp6 (vlib_buffer_t * p, ip4_to_ip6_set_fn_t fn, void *ctx,
   return 0;
 }
 
-/**
- * @brief Translate IPv4 fragmented packet to IPv6.
- *
- * @param p   Buffer to translate.
- * @param fn  The function to translate header.
- * @param ctx A context passed in the header translate function.
- *
- * @returns 0 on success, non-zero value otherwise.
- */
-always_inline int
-ip4_to_ip6_fragmented (vlib_buffer_t * p, ip4_to_ip6_set_fn_t fn, void *ctx)
-{
-  ip4_header_t *ip4;
-  ip6_header_t *ip6;
-  ip6_frag_hdr_t *frag;
-  int rv;
-
-  ip4 = vlib_buffer_get_current (p);
-  frag = (ip6_frag_hdr_t *) u8_ptr_add (ip4, sizeof (*ip4) - sizeof (*frag));
-  ip6 =
-    (ip6_header_t *) u8_ptr_add (ip4,
-				 sizeof (*ip4) - sizeof (*frag) -
-				 sizeof (*ip6));
-  vlib_buffer_advance (p, sizeof (*ip4) - sizeof (*ip6) - sizeof (*frag));
-
-  //We know that the protocol was one of ICMP, TCP or UDP
-  //because the first fragment was found and cached
-  frag->next_hdr =
-    (ip4->protocol == IP_PROTOCOL_ICMP) ? IP_PROTOCOL_ICMP6 : ip4->protocol;
-  frag->identification = frag_id_4to6 (ip4->fragment_id);
-  frag->rsv = 0;
-  frag->fragment_offset_and_more =
-    ip6_frag_hdr_offset_and_more (ip4_get_fragment_offset (ip4),
-				  clib_net_to_host_u16
-				  (ip4->flags_and_fragment_offset) &
-				  IP4_HEADER_FLAG_MORE_FRAGMENTS);
-
-  ip6->ip_version_traffic_class_and_flow_label =
-    clib_host_to_net_u32 ((6 << 28) + (ip4->tos << 20));
-  ip6->payload_length =
-    clib_host_to_net_u16 (clib_net_to_host_u16 (ip4->length) -
-			  sizeof (*ip4) + sizeof (*frag));
-  ip6->hop_limit = ip4->ttl;
-  ip6->protocol = IP_PROTOCOL_IPV6_FRAGMENTATION;
-
-  if ((rv = fn (ip4, ip6, ctx)) != 0)
-    return rv;
-
-  return 0;
-}
-
-/**
- * @brief Translate IPv4 UDP/TCP packet to IPv6.
- *
- * @param p   Buffer to translate.
- * @param fn  The function to translate header.
- * @param ctx A context passed in the header translate function.
- *
- * @returns 0 on success, non-zero value otherwise.
- */
-always_inline int
-ip4_to_ip6_tcp_udp (vlib_buffer_t * p, ip4_to_ip6_set_fn_t fn, void *ctx)
-{
-  ip4_header_t *ip4;
-  ip6_header_t *ip6;
-  ip_csum_t csum;
-  u16 *checksum;
-  ip6_frag_hdr_t *frag;
-  u32 frag_id;
-  int rv;
-  ip4_address_t old_src, old_dst;
-
-  ip4 = vlib_buffer_get_current (p);
-
-  if (ip4->protocol == IP_PROTOCOL_UDP)
-    {
-      udp_header_t *udp = ip4_next_header (ip4);
-      checksum = &udp->checksum;
-
-      //UDP checksum is optional over IPv4 but mandatory for IPv6
-      //We do not check udp->length sanity but use our safe computed value instead
-      if (PREDICT_FALSE (!*checksum))
-	{
-	  u16 udp_len = clib_host_to_net_u16 (ip4->length) - sizeof (*ip4);
-	  csum = ip_incremental_checksum (0, udp, udp_len);
-	  csum = ip_csum_with_carry (csum, clib_host_to_net_u16 (udp_len));
-	  csum =
-	    ip_csum_with_carry (csum, clib_host_to_net_u16 (IP_PROTOCOL_UDP));
-	  csum = ip_csum_with_carry (csum, *((u64 *) (&ip4->src_address)));
-	  *checksum = ~ip_csum_fold (csum);
-	}
-    }
-  else
-    {
-      tcp_header_t *tcp = ip4_next_header (ip4);
-      checksum = &tcp->checksum;
-    }
-
-  old_src.as_u32 = ip4->src_address.as_u32;
-  old_dst.as_u32 = ip4->dst_address.as_u32;
-
-  // Deal with fragmented packets
-  if (PREDICT_FALSE (ip4->flags_and_fragment_offset &
-		     clib_host_to_net_u16 (IP4_HEADER_FLAG_MORE_FRAGMENTS)))
-    {
-      ip6 =
-	(ip6_header_t *) u8_ptr_add (ip4,
-				     sizeof (*ip4) - sizeof (*ip6) -
-				     sizeof (*frag));
-      frag =
-	(ip6_frag_hdr_t *) u8_ptr_add (ip4, sizeof (*ip4) - sizeof (*frag));
-      frag_id = frag_id_4to6 (ip4->fragment_id);
-      vlib_buffer_advance (p, sizeof (*ip4) - sizeof (*ip6) - sizeof (*frag));
-    }
-  else
-    {
-      ip6 = (ip6_header_t *) (((u8 *) ip4) + sizeof (*ip4) - sizeof (*ip6));
-      vlib_buffer_advance (p, sizeof (*ip4) - sizeof (*ip6));
-      frag = NULL;
-    }
-
-  ip6->ip_version_traffic_class_and_flow_label =
-    clib_host_to_net_u32 ((6 << 28) + (ip4->tos << 20));
-  ip6->payload_length = u16_net_add (ip4->length, -sizeof (*ip4));
-  ip6->hop_limit = ip4->ttl;
-  ip6->protocol = ip4->protocol;
-
-  if (PREDICT_FALSE (frag != NULL))
-    {
-      frag->next_hdr = ip6->protocol;
-      frag->identification = frag_id;
-      frag->rsv = 0;
-      frag->fragment_offset_and_more = ip6_frag_hdr_offset_and_more (0, 1);
-      ip6->protocol = IP_PROTOCOL_IPV6_FRAGMENTATION;
-      ip6->payload_length = u16_net_add (ip6->payload_length, sizeof (*frag));
-    }
-
-  if ((rv = fn (ip4, ip6, ctx)) != 0)
-    return rv;
-
-  csum = ip_csum_sub_even (*checksum, old_src.as_u32);
-  csum = ip_csum_sub_even (csum, old_dst.as_u32);
-  csum = ip_csum_add_even (csum, ip6->src_address.as_u64[0]);
-  csum = ip_csum_add_even (csum, ip6->src_address.as_u64[1]);
-  csum = ip_csum_add_even (csum, ip6->dst_address.as_u64[0]);
-  csum = ip_csum_add_even (csum, ip6->dst_address.as_u64[1]);
-  *checksum = ip_csum_fold (csum);
-
-  return 0;
-}
-
-/**
- * @brief Translate IPv4 packet to IPv6 (IP header only).
- *
- * @param p   Buffer to translate.
- * @param fn  The function to translate header.
- * @param ctx A context passed in the header translate function.
- *
- * @returns 0 on success, non-zero value otherwise.
- */
-always_inline int
-ip4_to_ip6 (vlib_buffer_t * p, ip4_to_ip6_set_fn_t fn, void *ctx)
-{
-  ip4_header_t *ip4;
-  ip6_header_t *ip6;
-  ip6_frag_hdr_t *frag;
-  u32 frag_id;
-  int rv;
-
-  ip4 = vlib_buffer_get_current (p);
-
-  // Deal with fragmented packets
-  if (PREDICT_FALSE (ip4->flags_and_fragment_offset &
-		     clib_host_to_net_u16 (IP4_HEADER_FLAG_MORE_FRAGMENTS)))
-    {
-      ip6 =
-	(ip6_header_t *) u8_ptr_add (ip4,
-				     sizeof (*ip4) - sizeof (*ip6) -
-				     sizeof (*frag));
-      frag =
-	(ip6_frag_hdr_t *) u8_ptr_add (ip4, sizeof (*ip4) - sizeof (*frag));
-      frag_id = frag_id_4to6 (ip4->fragment_id);
-      vlib_buffer_advance (p, sizeof (*ip4) - sizeof (*ip6) - sizeof (*frag));
-    }
-  else
-    {
-      ip6 = (ip6_header_t *) (((u8 *) ip4) + sizeof (*ip4) - sizeof (*ip6));
-      vlib_buffer_advance (p, sizeof (*ip4) - sizeof (*ip6));
-      frag = NULL;
-    }
-
-  ip6->ip_version_traffic_class_and_flow_label =
-    clib_host_to_net_u32 ((6 << 28) + (ip4->tos << 20));
-  ip6->payload_length = u16_net_add (ip4->length, -sizeof (*ip4));
-  ip6->hop_limit = ip4->ttl;
-  ip6->protocol = ip4->protocol;
-
-  if (PREDICT_FALSE (frag != NULL))
-    {
-      frag->next_hdr = ip6->protocol;
-      frag->identification = frag_id;
-      frag->rsv = 0;
-      frag->fragment_offset_and_more = ip6_frag_hdr_offset_and_more (0, 1);
-      ip6->protocol = IP_PROTOCOL_IPV6_FRAGMENTATION;
-      ip6->payload_length = u16_net_add (ip6->payload_length, sizeof (*frag));
-    }
-
-  if ((rv = fn (ip4, ip6, ctx)) != 0)
-    return rv;
-
-  return 0;
-}
-
 #endif /* __included_ip4_to_ip6_h__ */
diff --git a/src/vnet/ip/ip6_packet.h b/src/vnet/ip/ip6_packet.h
index 2ba55b75e09..e823214dac9 100644
--- a/src/vnet/ip/ip6_packet.h
+++ b/src/vnet/ip/ip6_packet.h
@@ -579,6 +579,67 @@ ip6_ext_header_find (vlib_main_t * vm, vlib_buffer_t * b,
   return result;
 }
 
+/*
+ * walk extension headers, looking for a specific extension header and last
+ * extension header, calculating length of all extension headers
+ *
+ * @param vm
+ * @param b buffer to limit search to
+ * @param ip6_header ipv6 header
+ * @param find_hdr extension header to look for (ignored if ext_hdr is NULL)
+ * @param length[out] length of all extension headers
+ * @param ext_hdr[out] extension header of type find_hdr (may be NULL)
+ * @param last_ext_hdr[out] last extension header (may be NULL)
+ *
+ * @return 0 on success, -1 on failure (ext headers crossing buffer boundary)
+ */
+always_inline int
+ip6_walk_ext_hdr (vlib_main_t * vm, vlib_buffer_t * b,
+		  const ip6_header_t * ip6_header, u8 find_hdr, u32 * length,
+		  ip6_ext_header_t ** ext_hdr,
+		  ip6_ext_header_t ** last_ext_hdr)
+{
+  if (!ip6_ext_hdr (ip6_header->protocol))
+    {
+      *length = 0;
+      *ext_hdr = NULL;
+      *last_ext_hdr = NULL;
+      return 0;
+    }
+  *length = 0;
+  ip6_ext_header_t *h = (void *) (ip6_header + 1);
+  if (!vlib_object_within_buffer_data (vm, b, h, ip6_ext_header_len (h)))
+    {
+      return -1;
+    }
+  *length += ip6_ext_header_len (h);
+  *last_ext_hdr = h;
+  *ext_hdr = NULL;
+  if (ip6_header->protocol == find_hdr)
+    {
+      *ext_hdr = h;
+    }
+  while (ip6_ext_hdr (h->next_hdr))
+    {
+      if (h->next_hdr == find_hdr)
+	{
+	  h = ip6_ext_next_header (h);
+	  *ext_hdr = h;
+	}
+      else
+	{
+	  h = ip6_ext_next_header (h);
+	}
+      if (!vlib_object_within_buffer_data (vm, b, h, ip6_ext_header_len (h)))
+	{
+	  return -1;
+	}
+      *length += ip6_ext_header_len (h);
+      *last_ext_hdr = h;
+    }
+  return 0;
+}
+
 /* *INDENT-OFF* */
 typedef CLIB_PACKED (struct {
   u8 next_hdr;
diff --git a/src/vnet/ip/ip6_to_ip4.h b/src/vnet/ip/ip6_to_ip4.h
index d13a0c1f104..17a11e6df0a 100644
--- a/src/vnet/ip/ip6_to_ip4.h
+++ b/src/vnet/ip/ip6_to_ip4.h
@@ -24,8 +24,12 @@
 /**
  * IPv6 to IPv4 set call back function type
  */
-typedef int (*ip6_to_ip4_set_fn_t) (ip6_header_t * ip6, ip4_header_t * ip4,
-				    void *ctx);
+typedef int (*ip6_to_ip4_icmp_set_fn_t) (ip6_header_t * ip6,
+					 ip4_header_t * ip4, void *ctx);
+
+typedef int (*ip6_to_ip4_tcp_udp_set_fn_t) (vlib_buffer_t * b,
+					    ip6_header_t * ip6,
+					    ip4_header_t * ip4, void *ctx);
 
 /* *INDENT-OFF* */
 static u8 icmp6_to_icmp_updater_pointer_table[] =
@@ -47,6 +51,8 @@ static u8 icmp6_to_icmp_updater_pointer_table[] =
 /**
  * @brief Parse some useful information from IPv6 header.
  *
+ * @param vm              vlib main
+ * @param b               vlib buffer
  * @param ip6             IPv6 header.
  * @param buff_len        Buffer length.
  * @param l4_protocol     L4 protocol number.
@@ -56,21 +62,37 @@ static u8 icmp6_to_icmp_updater_pointer_table[] =
  * @returns 0 on success, non-zero value otherwise.
  */
 static_always_inline int
-ip6_parse (const ip6_header_t * ip6, u32 buff_len,
-	   u8 * l4_protocol, u16 * l4_offset, u16 * frag_hdr_offset)
+ip6_parse (vlib_main_t * vm, vlib_buffer_t * b, const ip6_header_t * ip6,
+	   u32 buff_len, u8 * l4_protocol, u16 * l4_offset,
+	   u16 * frag_hdr_offset)
 {
-  if (ip6->protocol == IP_PROTOCOL_IPV6_FRAGMENTATION)
+  ip6_ext_header_t *last_hdr, *frag_hdr;
+  u32 length;
+  if (ip6_walk_ext_hdr
+      (vm, b, ip6, IP_PROTOCOL_IPV6_FRAGMENTATION, &length, &frag_hdr,
+       &last_hdr))
     {
-      *l4_protocol = ((ip6_frag_hdr_t *) (ip6 + 1))->next_hdr;
-      *frag_hdr_offset = sizeof (*ip6);
-      *l4_offset = sizeof (*ip6) + sizeof (ip6_frag_hdr_t);
+      return -1;
+    }
+
+  if (length > 0)
+    {
+      if (frag_hdr)
+	{
+	  *frag_hdr_offset = (u8 *) frag_hdr - (u8 *) ip6;
+	}
+      else
+	{
+	  *frag_hdr_offset = 0;
+	}
+      *l4_protocol = last_hdr->next_hdr;
     }
   else
     {
-      *l4_protocol = ip6->protocol;
       *frag_hdr_offset = 0;
-      *l4_offset = sizeof (*ip6);
+      *l4_protocol = ip6->protocol;
     }
+  *l4_offset = sizeof (*ip6) + length;
 
   return (buff_len < (*l4_offset + 4)) ||
     (clib_net_to_host_u16 (ip6->payload_length) <
@@ -78,23 +100,32 @@ ip6_parse (const ip6_header_t * ip6, u32 buff_len,
 }
 
 /**
- * @brief Get TCP/UDP port number or ICMP id from IPv6 packet.
+ * @brief Get L4 information like port number or ICMP id from IPv6 packet.
  *
  * @param ip6        IPv6 header.
- * @param sender     1 get sender port, 0 get receiver port.
  * @param buffer_len Buffer length.
+ * @param ip_protocol L4 protocol
+ * @param src_port L4 src port or icmp id
+ * @param dst_post L4 dst port or icmp id
+ * @param icmp_type_or_tcp_flags ICMP type or TCP flags, if applicable
+ * @param tcp_ack_number TCP ack number, if applicable
+ * @param tcp_seq_number TCP seq number, if applicable
  *
- * @returns Port number on success, 0 otherwise.
+ * @returns 1 on success, 0 otherwise.
  */
 always_inline u16
-ip6_get_port (ip6_header_t * ip6, u8 sender, u16 buffer_len)
+ip6_get_port (vlib_main_t * vm, vlib_buffer_t * b, ip6_header_t * ip6,
+	      u16 buffer_len, u8 * ip_protocol, u16 * src_port,
+	      u16 * dst_port, u8 * icmp_type_or_tcp_flags,
+	      u32 * tcp_ack_number, u32 * tcp_seq_number)
 {
   u8 l4_protocol;
   u16 l4_offset;
   u16 frag_offset;
   u8 *l4;
 
-  if (ip6_parse (ip6, buffer_len, &l4_protocol, &l4_offset, &frag_offset))
+  if (ip6_parse
+      (vm, b, ip6, buffer_len, &l4_protocol, &l4_offset, &frag_offset))
     return 0;
 
   if (frag_offset &&
@@ -102,26 +133,45 @@ ip6_get_port (ip6_header_t * ip6, u8 sender, u16 buffer_len)
 			    u8_ptr_add (ip6, frag_offset))))
     return 0;			//Can't deal with non-first fragment for now
 
+  if (ip_protocol)
+    {
+      *ip_protocol = l4_protocol;
+    }
   l4 = u8_ptr_add (ip6, l4_offset);
   if (l4_protocol == IP_PROTOCOL_TCP || l4_protocol == IP_PROTOCOL_UDP)
     {
-      return (sender) ? ((udp_header_t *) (l4))->src_port : ((udp_header_t
-							      *)
-							     (l4))->dst_port;
+      if (src_port)
+	*src_port = ((udp_header_t *) (l4))->src_port;
+      if (dst_port)
+	*dst_port = ((udp_header_t *) (l4))->dst_port;
+      if (icmp_type_or_tcp_flags && l4_protocol == IP_PROTOCOL_TCP)
+	*icmp_type_or_tcp_flags = ((tcp_header_t *) (l4))->flags;
+      if (tcp_ack_number && l4_protocol == IP_PROTOCOL_TCP)
+	*tcp_ack_number = ((tcp_header_t *) (l4))->ack_number;
+      if (tcp_seq_number && l4_protocol == IP_PROTOCOL_TCP)
+	*tcp_seq_number = ((tcp_header_t *) (l4))->seq_number;
     }
   else if (l4_protocol == IP_PROTOCOL_ICMP6)
     {
       icmp46_header_t *icmp = (icmp46_header_t *) (l4);
+      if (icmp_type_or_tcp_flags)
+	*icmp_type_or_tcp_flags = ((icmp46_header_t *) (l4))->type;
       if (icmp->type == ICMP6_echo_request)
 	{
-	  return (sender) ? ((u16 *) (icmp))[2] : -1;
+	  if (src_port)
+	    *src_port = ((u16 *) (icmp))[2];
+	  if (dst_port)
+	    *dst_port = ((u16 *) (icmp))[2];
 	}
       else if (icmp->type == ICMP6_echo_reply)
 	{
-	  return (sender) ? -1 : ((u16 *) (icmp))[2];
+	  if (src_port)
+	    *src_port = ((u16 *) (icmp))[2];
+	  if (dst_port)
+	    *dst_port = ((u16 *) (icmp))[2];
 	}
     }
-  return 0;
+  return 1;
 }
 
 /**
@@ -223,14 +273,14 @@ icmp6_to_icmp_header (icmp46_header_t * icmp, ip6_header_t ** inner_ip6)
 /**
  * @brief Translate TOS value from IPv6 to IPv4.
  *
- * @param ip6 IPv6 header.
+ * @param ip_version_traffic_class_and_flow_label in network byte order
  *
  * @returns IPv4 TOS value.
  */
 static_always_inline u8
-ip6_translate_tos (const ip6_header_t * ip6)
+ip6_translate_tos (u32 ip_version_traffic_class_and_flow_label)
 {
-  return (clib_net_to_host_u32 (ip6->ip_version_traffic_class_and_flow_label)
+  return (clib_net_to_host_u32 (ip_version_traffic_class_and_flow_label)
 	  & 0x0ff00000) >> 20;
 }
 
@@ -246,8 +296,9 @@ ip6_translate_tos (const ip6_header_t * ip6)
  * @returns 0 on success, non-zero value otherwise.
  */
 always_inline int
-icmp6_to_icmp (vlib_buffer_t * p, ip6_to_ip4_set_fn_t fn, void *ctx,
-	       ip6_to_ip4_set_fn_t inner_fn, void *inner_ctx)
+icmp6_to_icmp (vlib_main_t * vm, vlib_buffer_t * p,
+	       ip6_to_ip4_icmp_set_fn_t fn, void *ctx,
+	       ip6_to_ip4_icmp_set_fn_t inner_fn, void *inner_ctx)
 {
   ip6_header_t *ip6, *inner_ip6;
   ip4_header_t *ip4, *inner_ip4;
@@ -285,7 +336,7 @@ icmp6_to_icmp (vlib_buffer_t * p, ip6_to_ip4_set_fn_t fn, void *ctx,
       //    TO
       //                               [ IPv4][IC][ IPv4][L4 header ...
 
-      if (ip6_parse (inner_ip6, ip6_pay_len - 8,
+      if (ip6_parse (vm, p, inner_ip6, ip6_pay_len - 8,
 		     &inner_protocol, &inner_l4_offset, &inner_frag_offset))
 	return -1;
 
@@ -336,7 +387,9 @@ icmp6_to_icmp (vlib_buffer_t * p, ip6_to_ip4_set_fn_t fn, void *ctx,
 
       inner_ip4->ip_version_and_header_length =
 	IP4_VERSION_AND_HEADER_LENGTH_NO_OPTIONS;
-      inner_ip4->tos = ip6_translate_tos (inner_ip6);
+      inner_ip4->tos =
+	ip6_translate_tos
+	(inner_ip6->ip_version_traffic_class_and_flow_label);
       inner_ip4->length =
 	u16_net_add (inner_ip6->payload_length,
 		     sizeof (*ip4) + sizeof (*ip6) - inner_l4_offset);
@@ -389,7 +442,7 @@ icmp6_to_icmp (vlib_buffer_t * p, ip6_to_ip4_set_fn_t fn, void *ctx,
 
   ip4->ip_version_and_header_length =
     IP4_VERSION_AND_HEADER_LENGTH_NO_OPTIONS;
-  ip4->tos = ip6_translate_tos (ip6);
+  ip4->tos = ip6_translate_tos (ip6->ip_version_traffic_class_and_flow_label);
   ip4->fragment_id = 0;
   ip4->flags_and_fragment_offset = 0;
   ip4->ttl = ip6->hop_limit;
@@ -412,220 +465,6 @@ icmp6_to_icmp (vlib_buffer_t * p, ip6_to_ip4_set_fn_t fn, void *ctx,
   return 0;
 }
 
-/**
- * @brief Translate IPv6 fragmented packet to IPv4.
- *
- * @param p   Buffer to translate.
- * @param fn  The function to translate header.
- * @param ctx A context passed in the header translate function.
- *
- * @returns 0 on success, non-zero value otherwise.
- */
-always_inline int
-ip6_to_ip4_fragmented (vlib_buffer_t * p, ip6_to_ip4_set_fn_t fn, void *ctx)
-{
-  ip6_header_t *ip6;
-  ip6_frag_hdr_t *frag;
-  ip4_header_t *ip4;
-  u16 frag_id;
-  u8 frag_more;
-  u16 frag_offset;
-  u8 l4_protocol;
-  u16 l4_offset;
-  int rv;
-
-  ip6 = vlib_buffer_get_current (p);
-
-  if (ip6_parse
-      (ip6, p->current_length, &l4_protocol, &l4_offset, &frag_offset))
-    return -1;
-
-  frag = (ip6_frag_hdr_t *) u8_ptr_add (ip6, frag_offset);
-  ip4 = (ip4_header_t *) u8_ptr_add (ip6, l4_offset - sizeof (*ip4));
-  vlib_buffer_advance (p, l4_offset - sizeof (*ip4));
-
-  frag_id = frag_id_6to4 (frag->identification);
-  frag_more = ip6_frag_hdr_more (frag);
-  frag_offset = ip6_frag_hdr_offset (frag);
-
-  if ((rv = fn (ip6, ip4, ctx)) != 0)
-    return rv;
-
-  ip4->ip_version_and_header_length =
-    IP4_VERSION_AND_HEADER_LENGTH_NO_OPTIONS;
-  ip4->tos = ip6_translate_tos (ip6);
-  ip4->length = u16_net_add (ip6->payload_length,
-			     sizeof (*ip4) - l4_offset + sizeof (*ip6));
-  ip4->fragment_id = frag_id;
-  ip4->flags_and_fragment_offset =
-    clib_host_to_net_u16 (frag_offset |
-			  (frag_more ? IP4_HEADER_FLAG_MORE_FRAGMENTS : 0));
-  ip4->ttl = ip6->hop_limit;
-  ip4->protocol =
-    (l4_protocol == IP_PROTOCOL_ICMP6) ? IP_PROTOCOL_ICMP : l4_protocol;
-  ip4->checksum = ip4_header_checksum (ip4);
-
-  return 0;
-}
-
-/**
- * @brief Translate IPv6 UDP/TCP packet to IPv4.
- *
- * @param p   Buffer to translate.
- * @param fn  The function to translate header.
- * @param ctx A context passed in the header translate function.
- *
- * @returns 0 on success, non-zero value otherwise.
- */
-always_inline int
-ip6_to_ip4_tcp_udp (vlib_buffer_t * p, ip6_to_ip4_set_fn_t fn, void *ctx,
-		    u8 udp_checksum)
-{
-  ip6_header_t *ip6;
-  u16 *checksum;
-  ip_csum_t csum = 0;
-  ip4_header_t *ip4;
-  u16 fragment_id;
-  u16 flags;
-  u16 frag_offset;
-  u8 l4_protocol;
-  u16 l4_offset;
-  int rv;
-  ip6_address_t old_src, old_dst;
-
-  ip6 = vlib_buffer_get_current (p);
-
-  if (ip6_parse
-      (ip6, p->current_length, &l4_protocol, &l4_offset, &frag_offset))
-    return -1;
-
-  if (l4_protocol == IP_PROTOCOL_TCP)
-    {
-      tcp_header_t *tcp = ip6_next_header (ip6);
-      checksum = &tcp->checksum;
-    }
-  else
-    {
-      udp_header_t *udp = ip6_next_header (ip6);
-      checksum = &udp->checksum;
-    }
-
-  old_src.as_u64[0] = ip6->src_address.as_u64[0];
-  old_src.as_u64[1] = ip6->src_address.as_u64[1];
-  old_dst.as_u64[0] = ip6->dst_address.as_u64[0];
-  old_dst.as_u64[1] = ip6->dst_address.as_u64[1];
-
-  ip4 = (ip4_header_t *) u8_ptr_add (ip6, l4_offset - sizeof (*ip4));
-
-  vlib_buffer_advance (p, l4_offset - sizeof (*ip4));
-
-  if (PREDICT_FALSE (frag_offset))
-    {
-      //Only the first fragment
-      ip6_frag_hdr_t *hdr = (ip6_frag_hdr_t *) u8_ptr_add (ip6, frag_offset);
-      fragment_id = frag_id_6to4 (hdr->identification);
-      flags = clib_host_to_net_u16 (IP4_HEADER_FLAG_MORE_FRAGMENTS);
-    }
-  else
-    {
-      fragment_id = 0;
-      flags = 0;
-    }
-
-  if ((rv = fn (ip6, ip4, ctx)) != 0)
-    return rv;
-
-  ip4->ip_version_and_header_length =
-    IP4_VERSION_AND_HEADER_LENGTH_NO_OPTIONS;
-  ip4->tos = ip6_translate_tos (ip6);
-  ip4->length = u16_net_add (ip6->payload_length,
-			     sizeof (*ip4) + sizeof (*ip6) - l4_offset);
-  ip4->fragment_id = fragment_id;
-  ip4->flags_and_fragment_offset = flags;
-  ip4->ttl = ip6->hop_limit;
-  ip4->protocol = l4_protocol;
-  ip4->checksum = ip4_header_checksum (ip4);
-
-  //UDP checksum is optional over IPv4
-  if (!udp_checksum && l4_protocol == IP_PROTOCOL_UDP)
-    {
-      *checksum = 0;
-    }
-  else
-    {
-      csum = ip_csum_sub_even (*checksum, old_src.as_u64[0]);
-      csum = ip_csum_sub_even (csum, old_src.as_u64[1]);
-      csum = ip_csum_sub_even (csum, old_dst.as_u64[0]);
-      csum = ip_csum_sub_even (csum, old_dst.as_u64[1]);
-      csum = ip_csum_add_even (csum, ip4->dst_address.as_u32);
-      csum = ip_csum_add_even (csum, ip4->src_address.as_u32);
-      *checksum = ip_csum_fold (csum);
-    }
-
-  return 0;
-}
-
-/**
- * @brief Translate IPv6 packet to IPv4 (IP header only).
- *
- * @param p   Buffer to translate.
- * @param fn  The function to translate header.
- * @param ctx A context passed in the header translate function.
- *
- * @returns 0 on success, non-zero value otherwise.
- */
-always_inline int
-ip6_to_ip4 (vlib_buffer_t * p, ip6_to_ip4_set_fn_t fn, void *ctx)
-{
-  ip6_header_t *ip6;
-  ip4_header_t *ip4;
-  u16 fragment_id;
-  u16 flags;
-  u16 frag_offset;
-  u8 l4_protocol;
-  u16 l4_offset;
-  int rv;
-
-  ip6 = vlib_buffer_get_current (p);
-
-  if (ip6_parse
-      (ip6, p->current_length, &l4_protocol, &l4_offset, &frag_offset))
-    return -1;
-
-  ip4 = (ip4_header_t *) u8_ptr_add (ip6, l4_offset - sizeof (*ip4));
-
-  vlib_buffer_advance (p, l4_offset - sizeof (*ip4));
-
-  if (PREDICT_FALSE (frag_offset))
-    {
-      //Only the first fragment
-      ip6_frag_hdr_t *hdr = (ip6_frag_hdr_t *) u8_ptr_add (ip6, frag_offset);
-      fragment_id = frag_id_6to4 (hdr->identification);
-      flags = clib_host_to_net_u16 (IP4_HEADER_FLAG_MORE_FRAGMENTS);
-    }
-  else
-    {
-      fragment_id = 0;
-      flags = 0;
-    }
-
-  if ((rv = fn (ip6, ip4, ctx)) != 0)
-    return rv;
-
-  ip4->ip_version_and_header_length =
-    IP4_VERSION_AND_HEADER_LENGTH_NO_OPTIONS;
-  ip4->tos = ip6_translate_tos (ip6);
-  ip4->length = u16_net_add (ip6->payload_length,
-			     sizeof (*ip4) + sizeof (*ip6) - l4_offset);
-  ip4->fragment_id = fragment_id;
-  ip4->flags_and_fragment_offset = flags;
-  ip4->ttl = ip6->hop_limit;
-  ip4->protocol = l4_protocol;
-  ip4->checksum = ip4_header_checksum (ip4);
-
-  return 0;
-}
-
 #endif /* __included_ip6_to_ip4_h__ */
 
 /*
diff --git a/src/vnet/ip/reass/ip4_sv_reass.c b/src/vnet/ip/reass/ip4_sv_reass.c
index d7130629219..b94e9b28cea 100644
--- a/src/vnet/ip/reass/ip4_sv_reass.c
+++ b/src/vnet/ip/reass/ip4_sv_reass.c
@@ -98,6 +98,9 @@ typedef struct
   bool is_complete;
   // ip protocol
   u8 ip_proto;
+  u8 icmp_type_or_tcp_flags;
+  u32 tcp_ack_number;
+  u32 tcp_seq_number;
   // l4 src port
   u16 l4_src_port;
   // l4 dst port
@@ -151,6 +154,9 @@ typedef struct
   // reference count for enabling/disabling feature - per interface
   u32 *feature_use_refcount_per_intf;
 
+  // reference count for enabling/disabling feature - per interface
+  u32 *output_feature_use_refcount_per_intf;
+
 } ip4_sv_reass_main_t;
 
 extern ip4_sv_reass_main_t ip4_sv_reass_main;
@@ -172,6 +178,7 @@ typedef enum
   REASS_FRAGMENT_CACHE,
   REASS_FINISH,
   REASS_FRAGMENT_FORWARD,
+  REASS_PASSTHROUGH,
 } ip4_sv_reass_trace_operation_e;
 
 typedef struct
@@ -193,7 +200,10 @@ format_ip4_sv_reass_trace (u8 * s, va_list * args)
   CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
   CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
   ip4_sv_reass_trace_t *t = va_arg (*args, ip4_sv_reass_trace_t *);
-  s = format (s, "reass id: %u, op id: %u ", t->reass_id, t->op_id);
+  if (REASS_PASSTHROUGH != t->action)
+    {
+      s = format (s, "reass id: %u, op id: %u ", t->reass_id, t->op_id);
+    }
   switch (t->action)
     {
     case REASS_FRAGMENT_CACHE:
@@ -211,6 +221,9 @@ format_ip4_sv_reass_trace (u8 * s, va_list * args)
 		t->ip_proto, clib_net_to_host_u16 (t->l4_src_port),
 		clib_net_to_host_u16 (t->l4_dst_port));
       break;
+    case REASS_PASSTHROUGH:
+      s = format (s, "[not-fragmented]");
+      break;
     }
   return s;
 }
@@ -223,13 +236,16 @@ ip4_sv_reass_add_trace (vlib_main_t * vm, vlib_node_runtime_t * node,
 {
   vlib_buffer_t *b = vlib_get_buffer (vm, bi);
   ip4_sv_reass_trace_t *t = vlib_add_trace (vm, node, b, sizeof (t[0]));
-  t->reass_id = reass->id;
+  if (reass)
+    {
+      t->reass_id = reass->id;
+      t->op_id = reass->trace_op_counter;
+      ++reass->trace_op_counter;
+    }
   t->action = action;
-  t->op_id = reass->trace_op_counter;
   t->ip_proto = ip_proto;
   t->l4_src_port = l4_src_port;
   t->l4_dst_port = l4_dst_port;
-  ++reass->trace_op_counter;
 #if 0
   static u8 *s = NULL;
   s = format (s, "%U", format_ip4_sv_reass_trace, NULL, NULL, t);
@@ -358,19 +374,29 @@ ip4_sv_reass_find_or_create (vlib_main_t * vm, ip4_sv_reass_main_t * rm,
 always_inline ip4_sv_reass_rc_t
 ip4_sv_reass_update (vlib_main_t * vm, vlib_node_runtime_t * node,
 		     ip4_sv_reass_main_t * rm, ip4_sv_reass_per_thread_t * rt,
-		     ip4_sv_reass_t * reass, u32 bi0)
+		     ip4_header_t * ip0, ip4_sv_reass_t * reass, u32 bi0)
 {
-  vlib_buffer_t *fb = vlib_get_buffer (vm, bi0);
+  vlib_buffer_t *b0 = vlib_get_buffer (vm, bi0);
   ip4_sv_reass_rc_t rc = IP4_SV_REASS_RC_OK;
-  ip4_header_t *fip = vlib_buffer_get_current (fb);
-  const u32 fragment_first = ip4_get_fragment_offset_bytes (fip);
+  const u32 fragment_first = ip4_get_fragment_offset_bytes (ip0);
   if (0 == fragment_first)
     {
-      reass->ip_proto = fip->protocol;
-      reass->l4_src_port = ip4_get_port (fip, 1);
-      reass->l4_dst_port = ip4_get_port (fip, 0);
+      reass->ip_proto = ip0->protocol;
+      reass->l4_src_port = ip4_get_port (ip0, 1);
+      reass->l4_dst_port = ip4_get_port (ip0, 0);
       if (!reass->l4_src_port || !reass->l4_dst_port)
 	return IP4_SV_REASS_RC_UNSUPP_IP_PROTO;
+      if (IP_PROTOCOL_TCP == reass->ip_proto)
+	{
+	  reass->icmp_type_or_tcp_flags = ((tcp_header_t *) (ip0 + 1))->flags;
+	  reass->tcp_ack_number = ((tcp_header_t *) (ip0 + 1))->ack_number;
+	  reass->tcp_seq_number = ((tcp_header_t *) (ip0 + 1))->seq_number;
+	}
+      else if (IP_PROTOCOL_ICMP == reass->ip_proto)
+	{
+	  reass->icmp_type_or_tcp_flags =
+	    ((icmp46_header_t *) (ip0 + 1))->type;
+	}
       reass->is_complete = true;
       vlib_buffer_t *b0 = vlib_get_buffer (vm, bi0);
       if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
@@ -383,7 +409,7 @@ ip4_sv_reass_update (vlib_main_t * vm, vlib_node_runtime_t * node,
   vec_add1 (reass->cached_buffers, bi0);
   if (!reass->is_complete)
     {
-      if (PREDICT_FALSE (fb->flags & VLIB_BUFFER_IS_TRACED))
+      if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
 	{
 	  ip4_sv_reass_add_trace (vm, node, rm, reass, bi0,
 				  REASS_FRAGMENT_CACHE, ~0, ~0, ~0);
@@ -398,7 +424,8 @@ ip4_sv_reass_update (vlib_main_t * vm, vlib_node_runtime_t * node,
 
 always_inline uword
 ip4_sv_reass_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
-		     vlib_frame_t * frame, bool is_feature, bool is_custom)
+		     vlib_frame_t * frame, bool is_feature,
+		     bool is_output_feature, bool is_custom)
 {
   u32 *from = vlib_frame_vector_args (frame);
   u32 n_left_from, n_left_to_next, *to_next, next_index;
@@ -423,14 +450,52 @@ ip4_sv_reass_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 	  bi0 = from[0];
 	  b0 = vlib_get_buffer (vm, bi0);
 
-	  ip4_header_t *ip0 = vlib_buffer_get_current (b0);
+	  ip4_header_t *ip0 =
+	    (ip4_header_t *) u8_ptr_add (vlib_buffer_get_current (b0),
+					 is_output_feature *
+					 vnet_buffer (b0)->
+					 ip.save_rewrite_length);
 	  if (!ip4_get_fragment_more (ip0) && !ip4_get_fragment_offset (ip0))
 	    {
 	      // this is a regular packet - no fragmentation
+	      if (is_custom)
+		{
+		  next0 = vnet_buffer (b0)->ip.reass.next_index;
+		}
+	      else
+		{
+		  next0 = IP4_SV_REASSEMBLY_NEXT_INPUT;
+		}
+	      vnet_buffer (b0)->ip.reass.save_rewrite_length =
+		vnet_buffer (b0)->ip.save_rewrite_length;
+	      vnet_buffer (b0)->ip.reass.is_non_first_fragment = 0;
 	      vnet_buffer (b0)->ip.reass.ip_proto = ip0->protocol;
+	      if (IP_PROTOCOL_TCP == ip0->protocol)
+		{
+		  vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags =
+		    ((tcp_header_t *) (ip0 + 1))->flags;
+		  vnet_buffer (b0)->ip.reass.tcp_ack_number =
+		    ((tcp_header_t *) (ip0 + 1))->ack_number;
+		  vnet_buffer (b0)->ip.reass.tcp_seq_number =
+		    ((tcp_header_t *) (ip0 + 1))->seq_number;
+		}
+	      else if (IP_PROTOCOL_ICMP == ip0->protocol)
+		{
+		  vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags =
+		    ((icmp46_header_t *) (ip0 + 1))->type;
+		}
 	      vnet_buffer (b0)->ip.reass.l4_src_port = ip4_get_port (ip0, 1);
 	      vnet_buffer (b0)->ip.reass.l4_dst_port = ip4_get_port (ip0, 0);
-	      next0 = IP4_SV_REASSEMBLY_NEXT_INPUT;
+	      if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
+		{
+		  ip4_sv_reass_add_trace (vm, node, rm, NULL, bi0,
+					  REASS_PASSTHROUGH,
+					  vnet_buffer (b0)->ip.reass.ip_proto,
+					  vnet_buffer (b0)->ip.
+					  reass.l4_src_port,
+					  vnet_buffer (b0)->ip.
+					  reass.l4_dst_port);
+		}
 	      goto packet_enqueue;
 	    }
 	  const u32 fragment_first = ip4_get_fragment_offset_bytes (ip0);
@@ -474,10 +539,27 @@ ip4_sv_reass_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 
 	  if (reass->is_complete)
 	    {
+	      if (is_custom)
+		{
+		  next0 = vnet_buffer (b0)->ip.reass.next_index;
+		}
+	      else
+		{
+		  next0 = IP4_SV_REASSEMBLY_NEXT_INPUT;
+		}
+	      vnet_buffer (b0)->ip.reass.save_rewrite_length =
+		vnet_buffer (b0)->ip.save_rewrite_length;
+	      vnet_buffer (b0)->ip.reass.is_non_first_fragment =
+		! !fragment_first;
 	      vnet_buffer (b0)->ip.reass.ip_proto = reass->ip_proto;
+	      vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags =
+		reass->icmp_type_or_tcp_flags;
+	      vnet_buffer (b0)->ip.reass.tcp_ack_number =
+		reass->tcp_ack_number;
+	      vnet_buffer (b0)->ip.reass.tcp_seq_number =
+		reass->tcp_seq_number;
 	      vnet_buffer (b0)->ip.reass.l4_src_port = reass->l4_src_port;
 	      vnet_buffer (b0)->ip.reass.l4_dst_port = reass->l4_dst_port;
-	      next0 = IP4_SV_REASSEMBLY_NEXT_INPUT;
 	      error0 = IP4_ERROR_NONE;
 	      if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
 		{
@@ -491,7 +573,7 @@ ip4_sv_reass_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 	    }
 
 	  ip4_sv_reass_rc_t rc =
-	    ip4_sv_reass_update (vm, node, rm, rt, reass, bi0);
+	    ip4_sv_reass_update (vm, node, rm, rt, ip0, reass, bi0);
 	  switch (rc)
 	    {
 	    case IP4_SV_REASS_RC_OK:
@@ -538,7 +620,18 @@ ip4_sv_reass_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 		to_next[0] = bi0;
 		to_next += 1;
 		n_left_to_next -= 1;
+		ASSERT (vnet_buffer (b0)->ip.save_rewrite_length < (2 << 14));
+		vnet_buffer (b0)->ip.reass.save_rewrite_length =
+		  vnet_buffer (b0)->ip.save_rewrite_length;
+		vnet_buffer (b0)->ip.reass.is_non_first_fragment =
+		  ! !ip4_get_fragment_offset (vlib_buffer_get_current (b0));
 		vnet_buffer (b0)->ip.reass.ip_proto = reass->ip_proto;
+		vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags =
+		  reass->icmp_type_or_tcp_flags;
+		vnet_buffer (b0)->ip.reass.tcp_ack_number =
+		  reass->tcp_ack_number;
+		vnet_buffer (b0)->ip.reass.tcp_seq_number =
+		  reass->tcp_seq_number;
 		vnet_buffer (b0)->ip.reass.l4_src_port = reass->l4_src_port;
 		vnet_buffer (b0)->ip.reass.l4_dst_port = reass->l4_dst_port;
 		if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
@@ -568,10 +661,6 @@ ip4_sv_reass_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 	      b0 = vlib_get_buffer (vm, bi0);
 	      vnet_feature_next (&next0, b0);
 	    }
-	  if (is_custom)
-	    {
-	      next0 = vnet_buffer (b0)->ip.reass.next_index;
-	    }
 	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
 					   to_next, n_left_to_next,
 					   bi0, next0);
@@ -599,6 +688,7 @@ VLIB_NODE_FN (ip4_sv_reass_node) (vlib_main_t * vm,
 				  vlib_frame_t * frame)
 {
   return ip4_sv_reass_inline (vm, node, frame, false /* is_feature */ ,
+			      false /* is_output_feature */ ,
 			      false /* is_custom */ );
 }
 
@@ -625,6 +715,7 @@ VLIB_NODE_FN (ip4_sv_reass_node_feature) (vlib_main_t * vm,
 					  vlib_frame_t * frame)
 {
   return ip4_sv_reass_inline (vm, node, frame, true /* is_feature */ ,
+			      false /* is_output_feature */ ,
 			      false /* is_custom */ );
 }
 
@@ -654,6 +745,42 @@ VNET_FEATURE_INIT (ip4_sv_reass_feature) = {
 };
 /* *INDENT-ON* */
 
+VLIB_NODE_FN (ip4_sv_reass_node_output_feature) (vlib_main_t * vm,
+						 vlib_node_runtime_t * node,
+						 vlib_frame_t * frame)
+{
+  return ip4_sv_reass_inline (vm, node, frame, true /* is_feature */ ,
+			      true /* is_output_feature */ ,
+			      false /* is_custom */ );
+}
+
+
+/* *INDENT-OFF* */
+VLIB_REGISTER_NODE (ip4_sv_reass_node_output_feature) = {
+    .name = "ip4-sv-reassembly-output-feature",
+    .vector_size = sizeof (u32),
+    .format_trace = format_ip4_sv_reass_trace,
+    .n_errors = ARRAY_LEN (ip4_sv_reass_error_strings),
+    .error_strings = ip4_sv_reass_error_strings,
+    .n_next_nodes = IP4_SV_REASSEMBLY_N_NEXT,
+    .next_nodes =
+        {
+                [IP4_SV_REASSEMBLY_NEXT_INPUT] = "ip4-input",
+                [IP4_SV_REASSEMBLY_NEXT_DROP] = "ip4-drop",
+                [IP4_SV_REASSEMBLY_NEXT_HANDOFF] = "ip4-sv-reass-feature-hoff",
+        },
+};
+/* *INDENT-ON* */
+
+/* *INDENT-OFF* */
+VNET_FEATURE_INIT (ip4_sv_reass_output_feature) = {
+    .arc_name = "ip4-output",
+    .node_name = "ip4-sv-reassembly-output-feature",
+    .runs_before = 0,
+    .runs_after = 0,
+};
+/* *INDENT-ON* */
+
 /* *INDENT-OFF* */
 VLIB_REGISTER_NODE (ip4_sv_reass_custom_node) = {
     .name = "ip4-sv-reassembly-custom-next",
@@ -677,6 +804,7 @@ VLIB_NODE_FN (ip4_sv_reass_custom_node) (vlib_main_t * vm,
 					 vlib_frame_t * frame)
 {
   return ip4_sv_reass_inline (vm, node, frame, false /* is_feature */ ,
+			      false /* is_output_feature */ ,
 			      true /* is_custom */ );
 }
 
@@ -824,6 +952,7 @@ ip4_sv_reass_init_function (vlib_main_t * vm)
     vlib_frame_queue_main_init (ip4_sv_reass_node_feature.index, 0);
 
   rm->feature_use_refcount_per_intf = NULL;
+  rm->output_feature_use_refcount_per_intf = NULL;
 
   return error;
 }
@@ -1010,9 +1139,8 @@ VLIB_CLI_COMMAND (show_ip4_sv_reass_cmd, static) = {
 vnet_api_error_t
 ip4_sv_reass_enable_disable (u32 sw_if_index, u8 enable_disable)
 {
-  return vnet_feature_enable_disable ("ip4-unicast",
-				      "ip4-sv-reassembly-feature",
-				      sw_if_index, enable_disable, 0, 0);
+  return ip4_sv_reass_enable_disable_with_refcnt (sw_if_index,
+						  enable_disable);
 }
 #endif /* CLIB_MARCH_VARIANT */
 
@@ -1177,7 +1305,8 @@ ip4_sv_reass_enable_disable_with_refcnt (u32 sw_if_index, int is_enable)
     }
   else
     {
-      --rm->feature_use_refcount_per_intf[sw_if_index];
+      if (rm->feature_use_refcount_per_intf[sw_if_index])
+	--rm->feature_use_refcount_per_intf[sw_if_index];
       if (!rm->feature_use_refcount_per_intf[sw_if_index])
 	return vnet_feature_enable_disable ("ip4-unicast",
 					    "ip4-sv-reassembly-feature",
@@ -1192,6 +1321,35 @@ ip4_sv_reass_custom_register_next_node (uword node_index)
   return vlib_node_add_next (vlib_get_main (), ip4_sv_reass_custom_node.index,
 			     node_index);
 }
+
+int
+ip4_sv_reass_output_enable_disable_with_refcnt (u32 sw_if_index,
+						int is_enable)
+{
+  ip4_sv_reass_main_t *rm = &ip4_sv_reass_main;
+  vec_validate (rm->output_feature_use_refcount_per_intf, sw_if_index);
+  if (is_enable)
+    {
+      if (!rm->output_feature_use_refcount_per_intf[sw_if_index])
+	{
+	  ++rm->output_feature_use_refcount_per_intf[sw_if_index];
+	  return vnet_feature_enable_disable ("ip4-output",
+					      "ip4-sv-reassembly-output-feature",
+					      sw_if_index, 1, 0, 0);
+	}
+      ++rm->output_feature_use_refcount_per_intf[sw_if_index];
+    }
+  else
+    {
+      if (rm->output_feature_use_refcount_per_intf[sw_if_index])
+	--rm->output_feature_use_refcount_per_intf[sw_if_index];
+      if (!rm->output_feature_use_refcount_per_intf[sw_if_index])
+	return vnet_feature_enable_disable ("ip4-output",
+					    "ip4-sv-reassembly-output-feature",
+					    sw_if_index, 0, 0, 0);
+    }
+  return 0;
+}
 #endif
 
 /*
diff --git a/src/vnet/ip/reass/ip4_sv_reass.h b/src/vnet/ip/reass/ip4_sv_reass.h
index cf9f36502a0..e926dbeebcc 100644
--- a/src/vnet/ip/reass/ip4_sv_reass.h
+++ b/src/vnet/ip/reass/ip4_sv_reass.h
@@ -45,6 +45,8 @@ vnet_api_error_t ip4_sv_reass_enable_disable (u32 sw_if_index,
 
 
 int ip4_sv_reass_enable_disable_with_refcnt (u32 sw_if_index, int is_enable);
+int ip4_sv_reass_output_enable_disable_with_refcnt (u32 sw_if_index,
+						    int is_enable);
 
 uword ip4_sv_reass_custom_register_next_node (uword node_index);
 
diff --git a/src/vnet/ip/reass/ip6_sv_reass.c b/src/vnet/ip/reass/ip6_sv_reass.c
index 0837f0606ec..442617703a1 100644
--- a/src/vnet/ip/reass/ip6_sv_reass.c
+++ b/src/vnet/ip/reass/ip6_sv_reass.c
@@ -96,6 +96,9 @@ typedef struct
   bool is_complete;
   // ip protocol
   u8 ip_proto;
+  u8 icmp_type_or_tcp_flags;
+  u32 tcp_ack_number;
+  u32 tcp_seq_number;
   // l4 src port
   u16 l4_src_port;
   // l4 dst port
@@ -170,6 +173,7 @@ typedef enum
   REASS_FRAGMENT_CACHE,
   REASS_FINISH,
   REASS_FRAGMENT_FORWARD,
+  REASS_PASSTHROUGH,
 } ip6_sv_reass_trace_operation_e;
 
 typedef struct
@@ -188,7 +192,10 @@ format_ip6_sv_reass_trace (u8 * s, va_list * args)
   CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
   CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
   ip6_sv_reass_trace_t *t = va_arg (*args, ip6_sv_reass_trace_t *);
-  s = format (s, "reass id: %u, op id: %u ", t->reass_id, t->op_id);
+  if (REASS_PASSTHROUGH != t->action)
+    {
+      s = format (s, "reass id: %u, op id: %u ", t->reass_id, t->op_id);
+    }
   switch (t->action)
     {
     case REASS_FRAGMENT_CACHE:
@@ -206,6 +213,9 @@ format_ip6_sv_reass_trace (u8 * s, va_list * args)
 		t->ip_proto, clib_net_to_host_u16 (t->l4_src_port),
 		clib_net_to_host_u16 (t->l4_dst_port));
       break;
+    case REASS_PASSTHROUGH:
+      s = format (s, "[not-fragmented]");
+      break;
     }
   return s;
 }
@@ -219,13 +229,16 @@ ip6_sv_reass_add_trace (vlib_main_t * vm, vlib_node_runtime_t * node,
 {
   vlib_buffer_t *b = vlib_get_buffer (vm, bi);
   ip6_sv_reass_trace_t *t = vlib_add_trace (vm, node, b, sizeof (t[0]));
-  t->reass_id = reass->id;
+  if (reass)
+    {
+      t->reass_id = reass->id;
+      t->op_id = reass->trace_op_counter;
+      ++reass->trace_op_counter;
+    }
   t->action = action;
-  t->op_id = reass->trace_op_counter;
   t->ip_proto = ip_proto;
   t->l4_src_port = l4_src_port;
   t->l4_dst_port = l4_dst_port;
-  ++reass->trace_op_counter;
 #if 0
   static u8 *s = NULL;
   s = format (s, "%U", format_ip6_sv_reass_trace, NULL, NULL, t);
@@ -391,18 +404,13 @@ ip6_sv_reass_update (vlib_main_t * vm, vlib_node_runtime_t * node,
   fvnb->ip.reass.next_range_bi = ~0;
   if (0 == fragment_first)
     {
-      ip6_ext_header_t *ext_hdr = (void *) frag_hdr;
-      while (ip6_ext_hdr (ext_hdr->next_hdr)
-	     && vlib_object_within_buffer_data (vm, fb, ext_hdr,
-						ext_hdr->n_data_u64s * 8))
-	{
-	  ext_hdr = ip6_ext_next_header (ext_hdr);
-	}
-      reass->ip_proto = ext_hdr->next_hdr;
-      reass->l4_src_port = ip6_get_port (fip, 1, fb->current_length);
-      reass->l4_dst_port = ip6_get_port (fip, 0, fb->current_length);
-      if (!reass->l4_src_port || !reass->l4_dst_port)
+      if (!ip6_get_port
+	  (vm, fb, fip, fb->current_length, &reass->ip_proto,
+	   &reass->l4_src_port, &reass->l4_dst_port,
+	   &reass->icmp_type_or_tcp_flags, &reass->tcp_ack_number,
+	   &reass->tcp_seq_number))
 	return IP6_SV_REASS_RC_UNSUPP_IP_PROTO;
+
       reass->is_complete = true;
       vlib_buffer_t *b0 = vlib_get_buffer (vm, bi0);
       if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
@@ -538,12 +546,34 @@ ip6_sv_reassembly_inline (vlib_main_t * vm,
 	  if (!frag_hdr)
 	    {
 	      // this is a regular packet - no fragmentation
-	      vnet_buffer (b0)->ip.reass.ip_proto = ip0->protocol;
-	      vnet_buffer (b0)->ip.reass.l4_src_port =
-		ip6_get_port (ip0, 1, b0->current_length);
-	      vnet_buffer (b0)->ip.reass.l4_dst_port =
-		ip6_get_port (ip0, 0, b0->current_length);
+	      if (!ip6_get_port
+		  (vm, b0, ip0, b0->current_length,
+		   &(vnet_buffer (b0)->ip.reass.ip_proto),
+		   &(vnet_buffer (b0)->ip.reass.l4_src_port),
+		   &(vnet_buffer (b0)->ip.reass.l4_dst_port),
+		   &(vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags),
+		   &(vnet_buffer (b0)->ip.reass.tcp_ack_number),
+		   &(vnet_buffer (b0)->ip.reass.tcp_seq_number)))
+		{
+		  error0 = IP6_ERROR_REASS_UNSUPP_IP_PROTO;
+		  next0 = IP6_SV_REASSEMBLY_NEXT_DROP;
+		  goto packet_enqueue;
+		}
+	      ASSERT (vnet_buffer (b0)->ip.save_rewrite_length < (2 << 14));
+	      vnet_buffer (b0)->ip.reass.save_rewrite_length =
+		vnet_buffer (b0)->ip.save_rewrite_length;
+	      vnet_buffer (b0)->ip.reass.is_non_first_fragment = 0;
 	      next0 = IP6_SV_REASSEMBLY_NEXT_INPUT;
+	      if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
+		{
+		  ip6_sv_reass_add_trace (vm, node, rm, NULL, bi0,
+					  REASS_PASSTHROUGH,
+					  vnet_buffer (b0)->ip.reass.ip_proto,
+					  vnet_buffer (b0)->ip.
+					  reass.l4_src_port,
+					  vnet_buffer (b0)->ip.
+					  reass.l4_dst_port);
+		}
 	      goto packet_enqueue;
 	    }
 	  vnet_buffer (b0)->ip.reass.ip6_frag_hdr_offset =
@@ -601,7 +631,18 @@ ip6_sv_reassembly_inline (vlib_main_t * vm,
 
 	  if (reass->is_complete)
 	    {
+	      ASSERT (vnet_buffer (b0)->ip.save_rewrite_length < (2 << 14));
+	      vnet_buffer (b0)->ip.reass.save_rewrite_length =
+		vnet_buffer (b0)->ip.save_rewrite_length;
+	      vnet_buffer (b0)->ip.reass.is_non_first_fragment =
+		! !ip6_frag_hdr_offset (frag_hdr);
 	      vnet_buffer (b0)->ip.reass.ip_proto = reass->ip_proto;
+	      vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags =
+		reass->icmp_type_or_tcp_flags;
+	      vnet_buffer (b0)->ip.reass.tcp_ack_number =
+		reass->tcp_ack_number;
+	      vnet_buffer (b0)->ip.reass.tcp_seq_number =
+		reass->tcp_seq_number;
 	      vnet_buffer (b0)->ip.reass.l4_src_port = reass->l4_src_port;
 	      vnet_buffer (b0)->ip.reass.l4_dst_port = reass->l4_dst_port;
 	      next0 = IP6_SV_REASSEMBLY_NEXT_INPUT;
@@ -668,7 +709,21 @@ ip6_sv_reassembly_inline (vlib_main_t * vm,
 		  {
 		    vnet_feature_next (&next0, b0);
 		  }
+		frag_hdr =
+		  vlib_buffer_get_current (b0) +
+		  vnet_buffer (b0)->ip.reass.ip6_frag_hdr_offset;
+		ASSERT (vnet_buffer (b0)->ip.save_rewrite_length < (2 << 14));
+		vnet_buffer (b0)->ip.reass.save_rewrite_length =
+		  vnet_buffer (b0)->ip.save_rewrite_length;
+		vnet_buffer (b0)->ip.reass.is_non_first_fragment =
+		  ! !ip6_frag_hdr_offset (frag_hdr);
 		vnet_buffer (b0)->ip.reass.ip_proto = reass->ip_proto;
+		vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags =
+		  reass->icmp_type_or_tcp_flags;
+		vnet_buffer (b0)->ip.reass.tcp_ack_number =
+		  reass->tcp_ack_number;
+		vnet_buffer (b0)->ip.reass.tcp_seq_number =
+		  reass->tcp_seq_number;
 		vnet_buffer (b0)->ip.reass.l4_src_port = reass->l4_src_port;
 		vnet_buffer (b0)->ip.reass.l4_dst_port = reass->l4_dst_port;
 		if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
@@ -1124,9 +1179,8 @@ VLIB_CLI_COMMAND (show_ip6_sv_reassembly_cmd, static) = {
 vnet_api_error_t
 ip6_sv_reass_enable_disable (u32 sw_if_index, u8 enable_disable)
 {
-  return vnet_feature_enable_disable ("ip6-unicast",
-				      "ip6-sv-reassembly-feature",
-				      sw_if_index, enable_disable, 0, 0);
+  return ip6_sv_reass_enable_disable_with_refcnt (sw_if_index,
+						  enable_disable);
 }
 #endif /* CLIB_MARCH_VARIANT */