BFD: IPv6 support

Change-Id: Iaa9538c7cca500c04cf2704e5bf87480543cfcdf
Signed-off-by: Klement Sekera <ksekera@cisco.com>

8 files changed, 394 insertions, 168 deletions

diff --git a/src/vnet/bfd/bfd_main.c b/src/vnet/bfd/bfd_main.c
index 62be1842..7e1a2ef2 100644
--- a/src/vnet/bfd/bfd_main.c
+++ b/src/vnet/bfd/bfd_main.c
@@ -34,16 +34,9 @@ bfd_us_to_clocks (bfd_main_t * bm, u64 us)
 
 static vlib_node_registration_t bfd_process_node;
 
-typedef enum
-{
-#define F(t, n) BFD_OUTPUT_##t,
-  foreach_bfd_transport (F)
-#undef F
-    BFD_OUTPUT_N_NEXT,
-} bfd_output_next_t;
-
-static u32 bfd_next_index_by_transport[] = {
-#define F(t, n) [BFD_TRANSPORT_##t] = BFD_OUTPUT_##t,
+/* set to 0 here, real values filled at startup */
+static u32 bfd_node_index_by_transport[] = {
+#define F(t, n) [BFD_TRANSPORT_##t] = 0,
   foreach_bfd_transport (F)
 #undef F
 };
@@ -378,7 +371,7 @@ bfd_input_format_trace (u8 * s, va_list * args)
 		      clib_net_to_host_u32 (pkt->des_min_tx));
 	  s = format (s, "    required min rx interval: %u\n",
 		      clib_net_to_host_u32 (pkt->req_min_rx));
-	  s = format (s, "    required min echo rx interval: %u\n",
+	  s = format (s, "    required min echo rx interval: %u",
 		      clib_net_to_host_u32 (pkt->req_min_echo_rx));
 	}
     }
@@ -426,10 +419,12 @@ bfd_add_transport_layer (vlib_main_t * vm, vlib_buffer_t * b,
   switch (bs->transport)
     {
     case BFD_TRANSPORT_UDP4:
-      /* fallthrough */
+      BFD_DBG ("Transport bfd via udp4, bs_idx=%u", bs->bs_idx);
+      bfd_add_udp4_transport (vm, b, &bs->udp);
+      break;
     case BFD_TRANSPORT_UDP6:
-      BFD_DBG ("Transport bfd via udp, bs_idx=%u", bs->bs_idx);
-      bfd_add_udp_transport (vm, b, &bs->udp);
+      BFD_DBG ("Transport bfd via udp6, bs_idx=%u", bs->bs_idx);
+      bfd_add_udp6_transport (vm, b, &bs->udp);
       break;
     }
 }
@@ -448,17 +443,14 @@ bfd_create_frame (vlib_main_t * vm, vlib_node_runtime_t * rt,
   vlib_buffer_t *b = vlib_get_buffer (vm, bi);
   ASSERT (b->current_data == 0);
 
-  u32 *to_next;
-  u32 n_left_to_next;
-
-  vlib_get_next_frame (vm, rt, bfd_next_index_by_transport[bs->transport],
-		       to_next, n_left_to_next);
+  vlib_frame_t *f =
+    vlib_get_frame_to_node (vm, bfd_node_index_by_transport[bs->transport]);
 
+  u32 *to_next = vlib_frame_vector_args (f);
   to_next[0] = bi;
-  n_left_to_next -= 1;
+  f->n_vectors = 1;
 
-  vlib_put_next_frame (vm, rt, bfd_next_index_by_transport[bs->transport],
-		       n_left_to_next);
+  vlib_put_frame_to_node (vm, bfd_node_index_by_transport[bs->transport], f);
   return b;
 }
 
@@ -680,13 +672,8 @@ VLIB_REGISTER_NODE (bfd_process_node, static) = {
   .function = bfd_process,
   .type = VLIB_NODE_TYPE_PROCESS,
   .name = "bfd-process",
-  .n_next_nodes = BFD_OUTPUT_N_NEXT,
-  .next_nodes =
-      {
-#define F(t, n) [BFD_OUTPUT_##t] = n,
-          foreach_bfd_transport (F)
-#undef F
-      },
+  .n_next_nodes = 0,
+  .next_nodes = {},
 };
 /* *INDENT-ON* */
 
@@ -734,6 +721,13 @@ bfd_main_init (vlib_main_t * vm)
   timing_wheel_init (&bm->wheel, now, bm->cpu_cps);
   bm->wheel_inaccuracy = 2 << bm->wheel.log2_clocks_per_bin;
 
+  vlib_node_t *node = NULL;
+#define F(t, n)                               \
+  node = vlib_get_node_by_name (vm, (u8 *)n); \
+  bfd_node_index_by_transport[BFD_TRANSPORT_##t] = node->index;\
+  BFD_DBG("node '%s' has index %u", n, node->index);
+  foreach_bfd_transport (F);
+#undef F
   return 0;
 }
 
diff --git a/src/vnet/bfd/bfd_main.h b/src/vnet/bfd/bfd_main.h
index cc82c839..20da381a 100644
--- a/src/vnet/bfd/bfd_main.h
+++ b/src/vnet/bfd/bfd_main.h
@@ -25,7 +25,7 @@
 #include <vnet/bfd/bfd_udp.h>
 
 #define foreach_bfd_transport(F) \
-  F (UDP4, "ip4-rewrite")  \
+  F (UDP4, "ip4-rewrite") \
   F (UDP6, "ip6-rewrite")
 
 typedef enum
diff --git a/src/vnet/bfd/bfd_udp.c b/src/vnet/bfd/bfd_udp.c
index c1596bf6..fe348404 100644
--- a/src/vnet/bfd/bfd_udp.c
+++ b/src/vnet/bfd/bfd_udp.c
@@ -31,53 +31,80 @@ static vlib_node_registration_t bfd_udp6_input_node;
 
 bfd_udp_main_t bfd_udp_main;
 
-void bfd_udp_transport_to_buffer (vlib_main_t *vm, vlib_buffer_t *b,
-                                  bfd_udp_session_t *bus)
+void bfd_add_udp4_transport (vlib_main_t *vm, vlib_buffer_t *b,
+                             bfd_udp_session_t *bus)
 {
   udp_header_t *udp;
-  u16 udp_length, ip_length;
-  bfd_udp_key_t *key = &bus->key;
+  const bfd_udp_key_t *key = &bus->key;
 
   b->flags |= VNET_BUFFER_LOCALLY_ORIGINATED;
-  if (ip46_address_is_ip4 (&key->local_addr))
-    {
-      ip4_header_t *ip4;
-      const size_t data_size = sizeof (*ip4) + sizeof (*udp);
-      vlib_buffer_advance (b, -data_size);
-      ip4 = vlib_buffer_get_current (b);
-      udp = (udp_header_t *)(ip4 + 1);
-      memset (ip4, 0, data_size);
-      ip4->ip_version_and_header_length = 0x45;
-      ip4->ttl = 255;
-      ip4->protocol = IP_PROTOCOL_UDP;
-      ip4->src_address.as_u32 = key->local_addr.ip4.as_u32;
-      ip4->dst_address.as_u32 = key->peer_addr.ip4.as_u32;
-
-      udp->src_port = clib_host_to_net_u16 (50000); /* FIXME */
-      udp->dst_port = clib_host_to_net_u16 (UDP_DST_PORT_bfd4);
-
-      /* fix ip length, checksum and udp length */
-      ip_length = vlib_buffer_length_in_chain (vm, b);
-
-      ip4->length = clib_host_to_net_u16 (ip_length);
-      ip4->checksum = ip4_header_checksum (ip4);
-
-      udp_length = ip_length - (sizeof (*ip4));
-      udp->length = clib_host_to_net_u16 (udp_length);
-    }
-  else
-    {
-      BFD_ERR ("not implemented");
-      abort ();
-    }
+  vnet_buffer (b)->ip.adj_index[VLIB_RX] = bus->adj_index;
+  vnet_buffer (b)->ip.adj_index[VLIB_TX] = bus->adj_index;
+  ip4_header_t *ip4;
+  const size_t headers_size = sizeof (*ip4) + sizeof (*udp);
+  vlib_buffer_advance (b, -headers_size);
+  ip4 = vlib_buffer_get_current (b);
+  udp = (udp_header_t *)(ip4 + 1);
+  memset (ip4, 0, headers_size);
+  ip4->ip_version_and_header_length = 0x45;
+  ip4->ttl = 255;
+  ip4->protocol = IP_PROTOCOL_UDP;
+  ip4->src_address.as_u32 = key->local_addr.ip4.as_u32;
+  ip4->dst_address.as_u32 = key->peer_addr.ip4.as_u32;
+
+  udp->src_port = clib_host_to_net_u16 (50000); /* FIXME */
+  udp->dst_port = clib_host_to_net_u16 (UDP_DST_PORT_bfd4);
+
+  /* fix ip length, checksum and udp length */
+  const u16 ip_length = vlib_buffer_length_in_chain (vm, b);
+
+  ip4->length = clib_host_to_net_u16 (ip_length);
+  ip4->checksum = ip4_header_checksum (ip4);
+
+  const u16 udp_length = ip_length - (sizeof (*ip4));
+  udp->length = clib_host_to_net_u16 (udp_length);
 }
 
-void bfd_add_udp_transport (vlib_main_t *vm, vlib_buffer_t *b,
-                            bfd_udp_session_t *bus)
+void bfd_add_udp6_transport (vlib_main_t *vm, vlib_buffer_t *b,
+                             bfd_udp_session_t *bus)
 {
+  udp_header_t *udp;
+  const bfd_udp_key_t *key = &bus->key;
+
+  b->flags |= VNET_BUFFER_LOCALLY_ORIGINATED;
   vnet_buffer (b)->ip.adj_index[VLIB_RX] = bus->adj_index;
   vnet_buffer (b)->ip.adj_index[VLIB_TX] = bus->adj_index;
-  bfd_udp_transport_to_buffer (vm, b, bus);
+  ip6_header_t *ip6;
+  const size_t headers_size = sizeof (*ip6) + sizeof (*udp);
+  vlib_buffer_advance (b, -headers_size);
+  ip6 = vlib_buffer_get_current (b);
+  udp = (udp_header_t *)(ip6 + 1);
+  memset (ip6, 0, headers_size);
+  ip6->ip_version_traffic_class_and_flow_label =
+      clib_host_to_net_u32 (0x6 << 28);
+  ip6->hop_limit = 255;
+  ip6->protocol = IP_PROTOCOL_UDP;
+  clib_memcpy (&ip6->src_address, &key->local_addr.ip6,
+               sizeof (ip6->src_address));
+  clib_memcpy (&ip6->dst_address, &key->peer_addr.ip6,
+               sizeof (ip6->dst_address));
+
+  udp->src_port = clib_host_to_net_u16 (50000); /* FIXME */
+  udp->dst_port = clib_host_to_net_u16 (UDP_DST_PORT_bfd6);
+
+  /* fix ip payload length and udp length */
+  const u16 udp_length = vlib_buffer_length_in_chain (vm, b) - (sizeof (*ip6));
+  udp->length = clib_host_to_net_u16 (udp_length);
+  ip6->payload_length = udp->length;
+
+  /* IPv6 UDP checksum is mandatory */
+  int bogus = 0;
+  udp->checksum = ip6_tcp_udp_icmp_compute_checksum (vm, b, ip6, &bogus);
+  ASSERT (bogus == 0);
+  if (udp->checksum == 0)
+    {
+      udp->checksum = 0xffff;
+    }
 }
 
 static bfd_session_t *bfd_lookup_session (bfd_udp_main_t *bum,
@@ -345,29 +372,29 @@ static bfd_udp_error_t bfd_udp4_verify_transport (const ip4_header_t *ip4,
   const bfd_udp_key_t *key = &bus->key;
   if (ip4->src_address.as_u32 != key->peer_addr.ip4.as_u32)
     {
-      BFD_ERR ("IP src addr mismatch, got %U, expected %U", format_ip4_address,
-               ip4->src_address.as_u32, format_ip4_address,
-               key->peer_addr.ip4.as_u32);
+      BFD_ERR ("IPv4 src addr mismatch, got %U, expected %U",
+               format_ip4_address, ip4->src_address.as_u8, format_ip4_address,
+               key->peer_addr.ip4.as_u8);
       return BFD_UDP_ERROR_BAD;
     }
   if (ip4->dst_address.as_u32 != key->local_addr.ip4.as_u32)
     {
-      BFD_ERR ("IP dst addr mismatch, got %U, expected %U", format_ip4_address,
-               ip4->dst_address.as_u32, format_ip4_address,
-               key->local_addr.ip4.as_u32);
+      BFD_ERR ("IPv4 dst addr mismatch, got %U, expected %U",
+               format_ip4_address, ip4->dst_address.as_u8, format_ip4_address,
+               key->local_addr.ip4.as_u8);
       return BFD_UDP_ERROR_BAD;
     }
   const u8 expected_ttl = 255;
   if (ip4->ttl != expected_ttl)
     {
-      BFD_ERR ("IP unexpected TTL value %d, expected %d", ip4->ttl,
+      BFD_ERR ("IPv4 unexpected TTL value %u, expected %u", ip4->ttl,
                expected_ttl);
       return BFD_UDP_ERROR_BAD;
     }
   if (clib_net_to_host_u16 (udp->src_port) < 49152 ||
       clib_net_to_host_u16 (udp->src_port) > 65535)
     {
-      BFD_ERR ("Invalid UDP src port %d, out of range <49152,65535>",
+      BFD_ERR ("Invalid UDP src port %u, out of range <49152,65535>",
                udp->src_port);
     }
   return BFD_UDP_ERROR_NONE;
@@ -460,10 +487,128 @@ static bfd_udp_error_t bfd_udp4_scan (vlib_main_t *vm, vlib_node_runtime_t *rt,
   return BFD_UDP_ERROR_NONE;
 }
 
-static bfd_udp_error_t bfd_udp6_scan (vlib_main_t *vm, vlib_buffer_t *b)
+static void bfd_udp6_find_headers (vlib_buffer_t *b, const ip6_header_t **ip6,
+                                   const udp_header_t **udp)
+{
+  /* sanity check first */
+  const i32 start = vnet_buffer (b)->ip.start_of_ip_header;
+  if (start < 0 && start < sizeof (b->pre_data))
+    {
+      BFD_ERR ("Start of ip header is before pre_data, ignoring");
+      *ip6 = NULL;
+      *udp = NULL;
+      return;
+    }
+  *ip6 = (ip6_header_t *)(b->data + start);
+  if ((u8 *)*ip6 > (u8 *)vlib_buffer_get_current (b))
+    {
+      BFD_ERR ("Start of ip header is beyond current data, ignoring");
+      *ip6 = NULL;
+      *udp = NULL;
+      return;
+    }
+  *udp = (udp_header_t *)((*ip6) + 1);
+}
+
+static bfd_udp_error_t bfd_udp6_verify_transport (const ip6_header_t *ip6,
+                                                  const udp_header_t *udp,
+                                                  const bfd_session_t *bs)
 {
-  /* TODO */
-  return BFD_UDP_ERROR_BAD;
+  const bfd_udp_session_t *bus = &bs->udp;
+  const bfd_udp_key_t *key = &bus->key;
+  if (ip6->src_address.as_u64[0] != key->peer_addr.ip6.as_u64[0] &&
+      ip6->src_address.as_u64[1] != key->peer_addr.ip6.as_u64[1])
+    {
+      BFD_ERR ("IP src addr mismatch, got %U, expected %U", format_ip6_address,
+               ip6, format_ip6_address, &key->peer_addr.ip6);
+      return BFD_UDP_ERROR_BAD;
+    }
+  if (ip6->dst_address.as_u64[0] != key->local_addr.ip6.as_u64[0] &&
+      ip6->dst_address.as_u64[1] != key->local_addr.ip6.as_u64[1])
+    {
+      BFD_ERR ("IP dst addr mismatch, got %U, expected %U", format_ip6_address,
+               ip6, format_ip6_address, &key->local_addr.ip6);
+      return BFD_UDP_ERROR_BAD;
+    }
+  const u8 expected_hop_limit = 255;
+  if (ip6->hop_limit != expected_hop_limit)
+    {
+      BFD_ERR ("IPv6 unexpected hop-limit value %u, expected %u",
+               ip6->hop_limit, expected_hop_limit);
+      return BFD_UDP_ERROR_BAD;
+    }
+  if (clib_net_to_host_u16 (udp->src_port) < 49152 ||
+      clib_net_to_host_u16 (udp->src_port) > 65535)
+    {
+      BFD_ERR ("Invalid UDP src port %u, out of range <49152,65535>",
+               udp->src_port);
+    }
+  return BFD_UDP_ERROR_NONE;
+}
+
+static bfd_udp_error_t bfd_udp6_scan (vlib_main_t *vm, vlib_node_runtime_t *rt,
+                                      vlib_buffer_t *b, bfd_session_t **bs_out)
+{
+  const bfd_pkt_t *pkt = vlib_buffer_get_current (b);
+  if (sizeof (*pkt) > b->current_length)
+    {
+      BFD_ERR (
+          "Payload size %d too small to hold bfd packet of minimum size %d",
+          b->current_length, sizeof (*pkt));
+      return BFD_UDP_ERROR_BAD;
+    }
+  const ip6_header_t *ip6;
+  const udp_header_t *udp;
+  bfd_udp6_find_headers (b, &ip6, &udp);
+  if (!ip6 || !udp)
+    {
+      BFD_ERR ("Couldn't find ip6 or udp header");
+      return BFD_UDP_ERROR_BAD;
+    }
+  if (!bfd_verify_pkt_common (pkt))
+    {
+      return BFD_UDP_ERROR_BAD;
+    }
+  bfd_session_t *bs = NULL;
+  if (pkt->your_disc)
+    {
+      BFD_DBG ("Looking up BFD session using discriminator %u",
+               pkt->your_disc);
+      bs = bfd_find_session_by_disc (bfd_udp_main.bfd_main, pkt->your_disc);
+    }
+  else
+    {
+      bfd_udp_key_t key;
+      memset (&key, 0, sizeof (key));
+      key.sw_if_index = vnet_buffer (b)->sw_if_index[VLIB_RX];
+      key.local_addr.ip6.as_u64[0] = ip6->dst_address.as_u64[0];
+      key.local_addr.ip6.as_u64[1] = ip6->dst_address.as_u64[1];
+      key.peer_addr.ip6.as_u64[0] = ip6->src_address.as_u64[0];
+      key.peer_addr.ip6.as_u64[1] = ip6->src_address.as_u64[1];
+      BFD_DBG ("Looking up BFD session using key (sw_if_index=%u, local=%U, "
+               "peer=%U)",
+               key.sw_if_index, format_ip6_address, &key.local_addr,
+               format_ip6_address, &key.peer_addr);
+      bs = bfd_lookup_session (&bfd_udp_main, &key);
+    }
+  if (!bs)
+    {
+      BFD_ERR ("BFD session lookup failed - no session matches BFD pkt");
+      return BFD_UDP_ERROR_BAD;
+    }
+  BFD_DBG ("BFD session found, bs_idx=%u", bs->bs_idx);
+  if (!bfd_verify_pkt_session (pkt, b->current_length, bs))
+    {
+      return BFD_UDP_ERROR_BAD;
+    }
+  bfd_udp_error_t err;
+  if (BFD_UDP_ERROR_NONE != (err = bfd_udp6_verify_transport (ip6, udp, bs)))
+    {
+      return err;
+    }
+  bfd_rpc_update_session (bs->bs_idx, pkt);
+  *bs_out = bs;
+  return BFD_UDP_ERROR_NONE;
 }
 
 /*
@@ -504,7 +649,7 @@ static uword bfd_udp_input (vlib_main_t *vm, vlib_node_runtime_t *rt,
       /* scan this bfd pkt. error0 is the counter index to bmp */
       if (is_ipv6)
         {
-          error0 = bfd_udp6_scan (vm, b0);
+          error0 = bfd_udp6_scan (vm, rt, b0, &bs);
         }
       else
         {
diff --git a/src/vnet/bfd/bfd_udp.h b/src/vnet/bfd/bfd_udp.h
index 51f5327b..2cd89ca2 100644
--- a/src/vnet/bfd/bfd_udp.h
+++ b/src/vnet/bfd/bfd_udp.h
@@ -42,8 +42,10 @@ typedef struct
   adj_index_t adj_index;
 } bfd_udp_session_t;
 
-void bfd_add_udp_transport (vlib_main_t * vm, vlib_buffer_t * b,
-			    bfd_udp_session_t * bs);
+void bfd_add_udp4_transport (vlib_main_t * vm, vlib_buffer_t * b,
+			     bfd_udp_session_t * bs);
+void bfd_add_udp6_transport (vlib_main_t * vm, vlib_buffer_t * b,
+			     bfd_udp_session_t * bs);
 
 #endif /* __included_bfd_udp_h__ */
 
diff --git a/test/bfd.py b/test/bfd.py
index 57a5bd86..51716813 100644
--- a/test/bfd.py
+++ b/test/bfd.py
@@ -111,14 +111,24 @@ class VppBFDUDPSession(VppObject):
     def local_addr(self):
         """ BFD session local address (VPP address) """
         if self._local_addr is None:
-            return self._interface.local_ip4
+            if self.af == AF_INET:
+                return self._interface.local_ip4
+            elif self.af == AF_INET6:
+                return self._interface.local_ip6
+            else:
+                raise Exception("Unexpected af %s' % af" % self.af)
         return self._local_addr
 
     @property
     def local_addr_n(self):
         """ BFD session local address (VPP address) - raw, suitable for API """
         if self._local_addr is None:
-            return self._interface.local_ip4n
+            if self.af == AF_INET:
+                return self._interface.local_ip4n
+            elif self.af == AF_INET6:
+                return self._interface.local_ip6n
+            else:
+                raise Exception("Unexpected af %s' % af" % self.af)
         return self._local_addr_n
 
     @property
diff --git a/test/test_bfd.py b/test/test_bfd.py
index b7832247..b56df339 100644
--- a/test/test_bfd.py
+++ b/test/test_bfd.py
@@ -62,36 +62,14 @@ class BFDAPITestCase(VppTestCase):
                             session1.bs_index)
 
 
-def create_packet(interface, ttl=255, src_port=50000, **kwargs):
-    p = (Ether(src=interface.remote_mac, dst=interface.local_mac) /
-         IP(src=interface.remote_ip4, dst=interface.local_ip4, ttl=ttl) /
-         UDP(sport=src_port, dport=BFD.udp_dport) /
-         BFD(*kwargs))
-    return p
-
-
-def verify_ip(test, packet, local_ip, remote_ip):
-    """ Verify correctness of IP layer. """
-    ip = packet[IP]
-    test.assert_equal(ip.src, local_ip, "IP source address")
-    test.assert_equal(ip.dst, remote_ip, "IP destination address")
-    test.assert_equal(ip.ttl, 255, "IP TTL")
-
-
-def verify_udp(test, packet):
-    """ Verify correctness of UDP layer. """
-    udp = packet[UDP]
-    test.assert_equal(udp.dport, BFD.udp_dport, "UDP destination port")
-    test.assert_in_range(udp.sport, BFD.udp_sport_min, BFD.udp_sport_max,
-                         "UDP source port")
-
-
 class BFDTestSession(object):
     """ BFD session as seen from test framework side """
 
-    def __init__(self, test, interface, detect_mult=3):
+    def __init__(self, test, interface, af, detect_mult=3):
         self.test = test
+        self.af = af
         self.interface = interface
+        self.udp_sport = 50000
         self.bfd_values = {
             'my_discriminator': 0,
             'desired_min_tx_interval': 100000,
@@ -103,7 +81,22 @@ class BFDTestSession(object):
         self.bfd_values.update(kwargs)
 
     def create_packet(self):
-        packet = create_packet(self.interface)
+        if self.af == AF_INET6:
+            packet = (Ether(src=self.interface.remote_mac,
+                            dst=self.interface.local_mac) /
+                      IPv6(src=self.interface.remote_ip6,
+                           dst=self.interface.local_ip6,
+                           hlim=255) /
+                      UDP(sport=self.udp_sport, dport=BFD.udp_dport) /
+                      BFD())
+        else:
+            packet = (Ether(src=self.interface.remote_mac,
+                            dst=self.interface.local_mac) /
+                      IP(src=self.interface.remote_ip4,
+                         dst=self.interface.local_ip4,
+                         ttl=255) /
+                      UDP(sport=self.udp_sport, dport=BFD.udp_dport) /
+                      BFD())
         self.test.logger.debug("BFD: Creating packet")
         for name, value in self.bfd_values.iteritems():
             self.test.logger.debug("BFD: setting packet.%s=%s", name, value)
@@ -125,41 +118,52 @@ class BFDTestSession(object):
                                "BFD - your discriminator")
 
 
-@unittest.skip("")
-class BFDTestCase(VppTestCase):
-    """Bidirectional Forwarding Detection (BFD)"""
-
-    @classmethod
-    def setUpClass(cls):
-        super(BFDTestCase, cls).setUpClass()
-        try:
-            cls.create_pg_interfaces([0])
-            cls.pg0.config_ip4()
-            cls.pg0.generate_remote_hosts()
-            cls.pg0.configure_ipv4_neighbors()
-            cls.pg0.admin_up()
-            cls.pg0.resolve_arp()
-
-        except Exception:
-            super(BFDTestCase, cls).tearDownClass()
-            raise
-
-    def setUp(self):
-        super(BFDTestCase, self).setUp()
-        self.vapi.want_bfd_events()
-        self.vpp_session = VppBFDUDPSession(
-            self, self.pg0, self.pg0.remote_ip4)
-        self.vpp_session.add_vpp_config()
-        self.vpp_session.admin_up()
-        self.test_session = BFDTestSession(self, self.pg0)
-        self.test_session.update(required_min_rx_interval=100000)
+class BFDCommonCode:
+    """Common code used by both IPv4 and IPv6 Test Cases"""
 
     def tearDown(self):
         self.vapi.collect_events()  # clear the event queue
         if not self.vpp_dead:
             self.vapi.want_bfd_events(enable_disable=0)
             self.vpp_session.remove_vpp_config()
-        super(BFDTestCase, self).tearDown()
+
+    def bfd_session_up(self):
+        self.pg_enable_capture([self.pg0])
+        self.logger.info("BFD: Waiting for slow hello")
+        p, timeout = self.wait_for_bfd_packet(2)
+        self.logger.info("BFD: Sending Init")
+        self.test_session.update(my_discriminator=randint(0, 40000000),
+                                 your_discriminator=p[BFD].my_discriminator,
+                                 state=BFDState.init,
+                                 required_min_rx_interval=100000)
+        self.test_session.send_packet()
+        self.logger.info("BFD: Waiting for event")
+        e = self.vapi.wait_for_event(1, "bfd_udp_session_details")
+        self.verify_event(e, expected_state=BFDState.up)
+        self.logger.info("BFD: Session is Up")
+        self.test_session.update(state=BFDState.up)
+
+    def verify_ip(self, packet):
+        """ Verify correctness of IP layer. """
+        if self.vpp_session.af == AF_INET6:
+            ip = packet[IPv6]
+            local_ip = self.pg0.local_ip6
+            remote_ip = self.pg0.remote_ip6
+            self.assert_equal(ip.hlim, 255, "IPv6 hop limit")
+        else:
+            ip = packet[IP]
+            local_ip = self.pg0.local_ip4
+            remote_ip = self.pg0.remote_ip4
+            self.assert_equal(ip.ttl, 255, "IPv4 TTL")
+        self.assert_equal(ip.src, local_ip, "IP source address")
+        self.assert_equal(ip.dst, remote_ip, "IP destination address")
+
+    def verify_udp(self, packet):
+        """ Verify correctness of UDP layer. """
+        udp = packet[UDP]
+        self.assert_equal(udp.dport, BFD.udp_dport, "UDP destination port")
+        self.assert_in_range(udp.sport, BFD.udp_sport_min, BFD.udp_sport_max,
+                             "UDP source port")
 
     def verify_event(self, event, expected_state):
         """ Verify correctness of event values. """
@@ -198,35 +202,64 @@ class BFDTestCase(VppTestCase):
         before = time.time()
         p = self.pg0.wait_for_packet(timeout=timeout)
         after = time.time()
+        self.logger.debug(ppp("Got packet:", p))
         bfd = p[BFD]
         if bfd is None:
             raise Exception(ppp("Unexpected or invalid BFD packet:", p))
         if bfd.payload:
             raise Exception(ppp("Unexpected payload in BFD packet:", bfd))
-        verify_ip(self, p, self.pg0.local_ip4, self.pg0.remote_ip4)
-        verify_udp(self, p)
+        self.verify_ip(p)
+        self.verify_udp(p)
         self.test_session.verify_packet(p)
         return p, after - before
 
-    def bfd_session_up(self):
-        self.pg_enable_capture([self.pg0])
-        self.logger.info("BFD: Waiting for slow hello")
-        p, ttp = self.wait_for_bfd_packet()
-        self.logger.info("BFD: Sending Init")
-        self.test_session.update(my_discriminator=randint(0, 40000000),
-                                 your_discriminator=p[BFD].my_discriminator,
-                                 state=BFDState.init)
-        self.test_session.send_packet()
-        self.logger.info("BFD: Waiting for event")
-        e = self.vapi.wait_for_event(1, "bfd_udp_session_details")
-        self.verify_event(e, expected_state=BFDState.up)
-        self.logger.info("BFD: Session is Up")
-        self.test_session.update(state=BFDState.up)
-
     def test_session_up(self):
         """ bring BFD session up """
         self.bfd_session_up()
 
+    def test_hold_up(self):
+        """ hold BFD session up """
+        self.bfd_session_up()
+        for i in range(5):
+            self.wait_for_bfd_packet()
+            self.test_session.send_packet()
+
+
+class BFD4TestCase(VppTestCase, BFDCommonCode):
+    """Bidirectional Forwarding Detection (BFD)"""
+
+    @classmethod
+    def setUpClass(cls):
+        super(BFD4TestCase, cls).setUpClass()
+        try:
+            cls.create_pg_interfaces([0])
+            cls.pg0.config_ip4()
+            cls.pg0.generate_remote_hosts()
+            cls.pg0.configure_ipv4_neighbors()
+            cls.pg0.admin_up()
+            cls.pg0.resolve_arp()
+
+        except Exception:
+            super(BFD4TestCase, cls).tearDownClass()
+            raise
+
+    def setUp(self):
+        super(BFD4TestCase, self).setUp()
+        self.vapi.want_bfd_events()
+        try:
+            self.vpp_session = VppBFDUDPSession(self, self.pg0,
+                                                self.pg0.remote_ip4)
+            self.vpp_session.add_vpp_config()
+            self.vpp_session.admin_up()
+            self.test_session = BFDTestSession(self, self.pg0, AF_INET)
+        except:
+            self.vapi.want_bfd_events(enable_disable=0)
+            raise
+
+    def tearDown(self):
+        BFDCommonCode.tearDown(self)
+        super(BFD4TestCase, self).tearDown()
+
     def test_slow_timer(self):
         """ verify slow periodic control frames while session down """
         self.pg_enable_capture([self.pg0])
@@ -261,13 +294,6 @@ class BFDTestCase(VppTestCase):
             return
         raise Exception(ppp("Received unexpected BFD packet:", p))
 
-    def test_hold_up(self):
-        """ hold BFD session up """
-        self.bfd_session_up()
-        for i in range(5):
-            self.wait_for_bfd_packet()
-            self.test_session.send_packet()
-
     def test_conn_down(self):
         """ verify session goes down after inactivity """
         self.bfd_session_up()
@@ -324,5 +350,42 @@ class BFDTestCase(VppTestCase):
                              1.10 * interval / us_in_sec,
                              "time between BFD packets")
 
+
+class BFD6TestCase(VppTestCase, BFDCommonCode):
+    """Bidirectional Forwarding Detection (BFD) (IPv6) """
+
+    @classmethod
+    def setUpClass(cls):
+        super(BFD6TestCase, cls).setUpClass()
+        try:
+            cls.create_pg_interfaces([0])
+            cls.pg0.config_ip6()
+            cls.pg0.configure_ipv6_neighbors()
+            cls.pg0.admin_up()
+            cls.pg0.resolve_ndp()
+
+        except Exception:
+            super(BFD6TestCase, cls).tearDownClass()
+            raise
+
+    def setUp(self):
+        super(BFD6TestCase, self).setUp()
+        self.vapi.want_bfd_events()
+        try:
+            self.vpp_session = VppBFDUDPSession(self, self.pg0,
+                                                self.pg0.remote_ip6,
+                                                af=AF_INET6)
+            self.vpp_session.add_vpp_config()
+            self.vpp_session.admin_up()
+            self.test_session = BFDTestSession(self, self.pg0, AF_INET6)
+            self.logger.debug(self.vapi.cli("show adj nbr"))
+        except:
+            self.vapi.want_bfd_events(enable_disable=0)
+            raise
+
+    def tearDown(self):
+        BFDCommonCode.tearDown(self)
+        super(BFD6TestCase, self).tearDown()
+
 if __name__ == '__main__':
     unittest.main(testRunner=VppTestRunner)
diff --git a/test/util.py b/test/util.py
index 79893602..24e9af44 100644
--- a/test/util.py
+++ b/test/util.py
@@ -76,19 +76,24 @@ class Host(object):
 
     @property
     def ip4(self):
-        """ IPv4 address """
+        """ IPv4 address - string """
         return self._ip4
 
     @property
     def ip4n(self):
-        """ IPv4 address """
+        """ IPv4 address of remote host - raw, suitable as API parameter."""
         return socket.inet_pton(socket.AF_INET, self._ip4)
 
     @property
     def ip6(self):
-        """ IPv6 address """
+        """ IPv6 address - string """
         return self._ip6
 
+    @property
+    def ip6n(self):
+        """ IPv6 address of remote host - raw, suitable as API parameter."""
+        return socket.inet_pton(socket.AF_INET6, self._ip6)
+
     def __init__(self, mac=None, ip4=None, ip6=None):
         self._mac = mac
         self._ip4 = ip4
diff --git a/test/vpp_interface.py b/test/vpp_interface.py
index e0a29f94..ee4a9ef6 100644
--- a/test/vpp_interface.py
+++ b/test/vpp_interface.py
@@ -131,7 +131,7 @@ class VppInterface(object):
                 2, count + 2):  # 0: network address, 1: local vpp address
             mac = "02:%02x:00:00:ff:%02x" % (self.sw_if_index, i)
             ip4 = "172.16.%u.%u" % (self.sw_if_index, i)
-            ip6 = "fd01:%04x::%04x" % (self.sw_if_index, i)
+            ip6 = "fd01:%x::%x" % (self.sw_if_index, i)
             host = Host(mac, ip4, ip6)
             self._remote_hosts.append(host)
             self._hosts_by_mac[mac] = host
@@ -155,7 +155,7 @@ class VppInterface(object):
         self.has_ip4_config = False
         self.ip4_table_id = 0
 
-        self._local_ip6 = "fd01:%04x::1" % self.sw_if_index
+        self._local_ip6 = "fd01:%x::1" % self.sw_if_index
         self._local_ip6n = socket.inet_pton(socket.AF_INET6, self.local_ip6)
         self.local_ip6_prefix_len = 64
         self.has_ip6_config = False
@@ -226,6 +226,13 @@ class VppInterface(object):
             self.has_ip6_config = False
         self.has_ip6_config = False
 
+    def configure_ipv6_neighbors(self):
+        """For every remote host assign neighbor's MAC to IPv6 address."""
+        for host in self._remote_hosts:
+            macn = host.mac.replace(":", "").decode('hex')
+            self.test.vapi.ip_neighbor_add_del(
+                self.sw_if_index, macn, host.ip6n, is_ipv6=1)
+
     def unconfig(self):
         """Unconfigure IPv6 and IPv4 address on the VPP interface."""
         self.unconfig_ip4()