ip: allow addrs from the same prefix on intf

Type: feature

Adding a prefix to an interface was not permitted if it overlapped
with another prefix on an interface which used the same FIB.

Loosen the restriction. Allow 2 or more addresses from the same
prefix on a single interface. Reference count the prefix to figure
out when a glean/connected route for the prefix needs to be added
or removed.

Added unit tests to check that the route is only removed when all
addresses in the prefix are removed from the interface.

Change-Id: I1a962ecb5e1ee65fc6d41f98a4cc097a51a55321
Signed-off-by: Matthew Smith <mgsmith@netgate.com>

6 files changed, 532 insertions, 109 deletions

diff --git a/src/vnet/ip/ip4_forward.c b/src/vnet/ip/ip4_forward.c
index 754bb21fe67..060787f9561 100644
--- a/src/vnet/ip/ip4_forward.c
+++ b/src/vnet/ip/ip4_forward.c
@@ -339,74 +339,122 @@ ip4_add_subnet_bcast_route (u32 fib_index,
 }
 
 static void
-ip4_add_interface_routes (u32 sw_if_index,
-			  ip4_main_t * im, u32 fib_index,
-			  ip_interface_address_t * a)
+ip4_add_interface_prefix_routes (ip4_main_t *im,
+				 u32 sw_if_index,
+				 u32 fib_index,
+				 ip_interface_address_t * a)
 {
   ip_lookup_main_t *lm = &im->lookup_main;
+  ip_interface_prefix_t *if_prefix;
   ip4_address_t *address = ip_interface_address_get_address (lm, a);
-  fib_prefix_t pfx = {
-    .fp_len = a->address_length,
+
+  ip_interface_prefix_key_t key = {
+    .prefix = {
+      .fp_len = a->address_length,
+      .fp_proto = FIB_PROTOCOL_IP4,
+      .fp_addr.ip4.as_u32 = address->as_u32 & im->fib_masks[a->address_length],
+    },
+    .sw_if_index = sw_if_index,
+  };
+
+  fib_prefix_t pfx_special = {
     .fp_proto = FIB_PROTOCOL_IP4,
-    .fp_addr.ip4 = *address,
   };
 
-  if (pfx.fp_len <= 30)
+  /* If prefix already set on interface, just increment ref count & return */
+  if_prefix = ip_get_interface_prefix (lm, &key);
+  if (if_prefix)
     {
-      /* a /30 or shorter - add a glean for the network address */
-      fib_table_entry_update_one_path (fib_index, &pfx,
-                                       FIB_SOURCE_INTERFACE,
-                                       (FIB_ENTRY_FLAG_CONNECTED |
-                                        FIB_ENTRY_FLAG_ATTACHED),
-                                       DPO_PROTO_IP4,
-                                       /* No next-hop address */
-                                       NULL,
-                                       sw_if_index,
-                                       // invalid FIB index
+      if_prefix->ref_count += 1;
+      return;
+    }
+
+  /* New prefix - allocate a pool entry, initialize it, add to the hash */
+  pool_get (lm->if_prefix_pool, if_prefix);
+  if_prefix->ref_count = 1;
+  if_prefix->src_ia_index = a - lm->if_address_pool;
+  clib_memcpy (&if_prefix->key, &key, sizeof (key));
+  mhash_set (&lm->prefix_to_if_prefix_index, &key,
+	     if_prefix - lm->if_prefix_pool, 0 /* old value */);
+
+  /* length <= 30 - add glean, drop first address, maybe drop bcast address */
+  if (a->address_length <= 30)
+    {
+      pfx_special.fp_len = a->address_length;
+      pfx_special.fp_addr.ip4.as_u32 = address->as_u32;
+
+      /* set the glean route for the prefix */
+      fib_table_entry_update_one_path (fib_index, &pfx_special,
+				       FIB_SOURCE_INTERFACE,
+				       (FIB_ENTRY_FLAG_CONNECTED |
+					FIB_ENTRY_FLAG_ATTACHED),
+				       DPO_PROTO_IP4,
+				       /* No next-hop address */
+				       NULL,
+				       sw_if_index,
+                                       /* invalid FIB index */
                                        ~0,
                                        1,
-                                       // no out-label stack
+                                       /* no out-label stack */
                                        NULL,
                                        FIB_ROUTE_PATH_FLAG_NONE);
 
-      /* Add the two broadcast addresses as drop */
-      fib_prefix_t net_pfx = {
-        .fp_len = 32,
-        .fp_proto = FIB_PROTOCOL_IP4,
-        .fp_addr.ip4.as_u32 = address->as_u32 & im->fib_masks[pfx.fp_len],
-      };
-      if (net_pfx.fp_addr.ip4.as_u32 != pfx.fp_addr.ip4.as_u32)
-        fib_table_entry_special_add(fib_index,
-                                    &net_pfx,
-                                    FIB_SOURCE_INTERFACE,
-                                    (FIB_ENTRY_FLAG_DROP |
-                                     FIB_ENTRY_FLAG_LOOSE_URPF_EXEMPT));
-      net_pfx.fp_addr.ip4.as_u32 |= ~im->fib_masks[pfx.fp_len];
-      if (net_pfx.fp_addr.ip4.as_u32 != pfx.fp_addr.ip4.as_u32)
-        ip4_add_subnet_bcast_route(fib_index, &net_pfx, sw_if_index);
-    }
-  else if (pfx.fp_len == 31)
-    {
-      u32 mask = clib_host_to_net_u32(1);
-      fib_prefix_t net_pfx = pfx;
+      /* set a drop route for the base address of the prefix */
+      pfx_special.fp_len = 32;
+      pfx_special.fp_addr.ip4.as_u32 =
+	address->as_u32 & im->fib_masks[a->address_length];
 
-      net_pfx.fp_len = 32;
-      net_pfx.fp_addr.ip4.as_u32 ^= mask;
+      if (pfx_special.fp_addr.ip4.as_u32 != address->as_u32)
+	fib_table_entry_special_add (fib_index, &pfx_special,
+				     FIB_SOURCE_INTERFACE,
+				     (FIB_ENTRY_FLAG_DROP |
+				      FIB_ENTRY_FLAG_LOOSE_URPF_EXEMPT));
 
-      /* a /31 - add the other end as an attached host */
-      fib_table_entry_update_one_path (fib_index, &net_pfx,
-                                       FIB_SOURCE_INTERFACE,
-                                       (FIB_ENTRY_FLAG_ATTACHED),
-                                       DPO_PROTO_IP4,
-                                       &net_pfx.fp_addr,
-                                       sw_if_index,
-                                       // invalid FIB index
+      /* set a route for the broadcast address of the prefix */
+      pfx_special.fp_len = 32;
+      pfx_special.fp_addr.ip4.as_u32 =
+	address->as_u32 | ~im->fib_masks[a->address_length];
+      if (pfx_special.fp_addr.ip4.as_u32 != address->as_u32)
+	ip4_add_subnet_bcast_route (fib_index, &pfx_special, sw_if_index);
+
+
+    }
+  /* length == 31 - add an attached route for the other address */
+  else if (a->address_length == 31)
+    {
+      pfx_special.fp_len = 32;
+      pfx_special.fp_addr.ip4.as_u32 =
+	address->as_u32 ^ clib_host_to_net_u32(1);
+
+      fib_table_entry_update_one_path (fib_index, &pfx_special,
+				       FIB_SOURCE_INTERFACE,
+				       (FIB_ENTRY_FLAG_ATTACHED),
+				       DPO_PROTO_IP4,
+				       &pfx_special.fp_addr,
+				       sw_if_index,
+                                       /* invalid FIB index */
                                        ~0,
                                        1,
                                        NULL,
                                        FIB_ROUTE_PATH_FLAG_NONE);
     }
-  pfx.fp_len = 32;
+}
+
+static void
+ip4_add_interface_routes (u32 sw_if_index,
+			  ip4_main_t * im, u32 fib_index,
+			  ip_interface_address_t * a)
+{
+  ip_lookup_main_t *lm = &im->lookup_main;
+  ip4_address_t *address = ip_interface_address_get_address (lm, a);
+  fib_prefix_t pfx = {
+    .fp_len = 32,
+    .fp_proto = FIB_PROTOCOL_IP4,
+    .fp_addr.ip4 = *address,
+  };
+
+  /* set special routes for the prefix if needed */
+  ip4_add_interface_prefix_routes (im, sw_if_index, fib_index, a);
 
   if (sw_if_index < vec_len (lm->classify_table_index_by_sw_if_index))
     {
@@ -443,45 +491,143 @@ ip4_add_interface_routes (u32 sw_if_index,
 }
 
 static void
-ip4_del_interface_routes (ip4_main_t * im,
-			  u32 fib_index,
-			  ip4_address_t * address, u32 address_length)
+ip4_del_interface_prefix_routes (ip4_main_t * im,
+				 u32 sw_if_index,
+				 u32 fib_index,
+				 ip4_address_t * address,
+				 u32 address_length)
 {
-  fib_prefix_t pfx = {
-    .fp_len = address_length,
+  ip_lookup_main_t *lm = &im->lookup_main;
+  ip_interface_prefix_t *if_prefix;
+
+  ip_interface_prefix_key_t key = {
+    .prefix = {
+      .fp_len = address_length,
+      .fp_proto = FIB_PROTOCOL_IP4,
+      .fp_addr.ip4.as_u32 = address->as_u32 & im->fib_masks[address_length],
+    },
+    .sw_if_index = sw_if_index,
+  };
+
+  fib_prefix_t pfx_special = {
+    .fp_len = 32,
     .fp_proto = FIB_PROTOCOL_IP4,
-    .fp_addr.ip4 = *address,
   };
 
-  if (pfx.fp_len <= 30)
+  if_prefix = ip_get_interface_prefix (lm, &key);
+  if (!if_prefix)
     {
-      fib_prefix_t net_pfx = {
-        .fp_len = 32,
-        .fp_proto = FIB_PROTOCOL_IP4,
-        .fp_addr.ip4.as_u32 = address->as_u32 & im->fib_masks[pfx.fp_len],
-      };
-      if (net_pfx.fp_addr.ip4.as_u32 != pfx.fp_addr.ip4.as_u32)
-        fib_table_entry_special_remove(fib_index,
-                                       &net_pfx,
-                                       FIB_SOURCE_INTERFACE);
-      net_pfx.fp_addr.ip4.as_u32 |= ~im->fib_masks[pfx.fp_len];
-      if (net_pfx.fp_addr.ip4.as_u32 != pfx.fp_addr.ip4.as_u32)
-        fib_table_entry_special_remove(fib_index,
-                                       &net_pfx,
-                                       FIB_SOURCE_INTERFACE);
-      fib_table_entry_delete (fib_index, &pfx, FIB_SOURCE_INTERFACE);
+      clib_warning ("Prefix not found while deleting %U",
+		    format_ip4_address_and_length, address, address_length);
+      return;
     }
-    else if (pfx.fp_len == 31)
+
+  if_prefix->ref_count -= 1;
+
+  /*
+   * Routes need to be adjusted if:
+   * - deleting last intf addr in prefix
+   * - deleting intf addr used as default source address in glean adjacency
+   *
+   * We're done now otherwise
+   */
+  if ((if_prefix->ref_count > 0) &&
+      !pool_is_free_index (lm->if_address_pool, if_prefix->src_ia_index))
+    return;
+
+  /* length <= 30, delete glean route, first address, last address */
+  if (address_length <= 30)
     {
-      u32 mask = clib_host_to_net_u32(1);
-      fib_prefix_t net_pfx = pfx;
 
-      net_pfx.fp_len = 32;
-      net_pfx.fp_addr.ip4.as_u32 ^= mask;
+      /* remove glean route for prefix */
+      pfx_special.fp_addr.ip4 = *address;
+      pfx_special.fp_len = address_length;
+      fib_table_entry_delete (fib_index, &pfx_special, FIB_SOURCE_INTERFACE);
+
+      /* if no more intf addresses in prefix, remove other special routes */
+      if (!if_prefix->ref_count)
+	{
+	  /* first address in prefix */
+	  pfx_special.fp_addr.ip4.as_u32 =
+	    address->as_u32 & im->fib_masks[address_length];
+	  pfx_special.fp_len = 32;
+
+	  if (pfx_special.fp_addr.ip4.as_u32 != address->as_u32)
+	  fib_table_entry_special_remove (fib_index,
+					  &pfx_special,
+					  FIB_SOURCE_INTERFACE);
+
+	  /* prefix broadcast address */
+	  pfx_special.fp_addr.ip4.as_u32 =
+	    address->as_u32 | ~im->fib_masks[address_length];
+	  pfx_special.fp_len = 32;
 
-      fib_table_entry_delete (fib_index, &net_pfx, FIB_SOURCE_INTERFACE);
+	  if (pfx_special.fp_addr.ip4.as_u32 != address->as_u32)
+	  fib_table_entry_special_remove (fib_index,
+					  &pfx_special,
+					  FIB_SOURCE_INTERFACE);
+	}
+      else
+	/* default source addr just got deleted, find another */
+	{
+	  ip_interface_address_t *new_src_ia = NULL;
+	  ip4_address_t *new_src_addr = NULL;
+
+	  new_src_addr =
+	    ip4_interface_address_matching_destination
+	      (im, address, sw_if_index, &new_src_ia);
+
+	  if_prefix->src_ia_index = new_src_ia - lm->if_address_pool;
+
+	  pfx_special.fp_len = address_length;
+	  pfx_special.fp_addr.ip4 = *new_src_addr;
+
+	  /* set new glean route for the prefix */
+	  fib_table_entry_update_one_path (fib_index, &pfx_special,
+					   FIB_SOURCE_INTERFACE,
+					   (FIB_ENTRY_FLAG_CONNECTED |
+					    FIB_ENTRY_FLAG_ATTACHED),
+					   DPO_PROTO_IP4,
+					   /* No next-hop address */
+					   NULL,
+					   sw_if_index,
+					   /* invalid FIB index */
+					   ~0,
+					   1,
+					   /* no out-label stack */
+					   NULL,
+					   FIB_ROUTE_PATH_FLAG_NONE);
+	  return;
+	}
+    }
+  /* length == 31, delete attached route for the other address */
+  else if (address_length == 31)
+    {
+      pfx_special.fp_addr.ip4.as_u32 =
+	address->as_u32 ^ clib_host_to_net_u32(1);
+
+      fib_table_entry_delete (fib_index, &pfx_special, FIB_SOURCE_INTERFACE);
     }
 
+  mhash_unset (&lm->prefix_to_if_prefix_index, &key, 0 /* old_value */);
+  pool_put (lm->if_prefix_pool, if_prefix);
+}
+
+static void
+ip4_del_interface_routes (u32 sw_if_index,
+			  ip4_main_t * im,
+			  u32 fib_index,
+			  ip4_address_t * address, u32 address_length)
+{
+  fib_prefix_t pfx = {
+    .fp_len = address_length,
+    .fp_proto = FIB_PROTOCOL_IP4,
+    .fp_addr.ip4 = *address,
+  };
+
+  ip4_del_interface_prefix_routes (im, sw_if_index, fib_index,
+				   address, address_length);
+
   pfx.fp_len = 32;
   fib_table_entry_delete (fib_index, &pfx, FIB_SOURCE_INTERFACE);
 }
@@ -579,6 +725,13 @@ ip4_add_del_interface_address_internal (vlib_main_t * vm,
                                                       address,
                                                       address_length))
                      {
+		       /* an intf may have >1 addr from the same prefix */
+		       if ((sw_if_index == sif->sw_if_index) &&
+			   (ia->address_length == address_length) &&
+			   (x->as_u32 != address->as_u32))
+		         continue;
+
+		       /* error if the length or intf was different */
                        vnm->api_errno = VNET_API_ERROR_DUPLICATE_IF_ADDRESS;
 
                        return
@@ -610,7 +763,8 @@ ip4_add_del_interface_address_internal (vlib_main_t * vm,
   if (vnet_sw_interface_is_admin_up (vnm, sw_if_index))
     {
       if (is_del)
-	ip4_del_interface_routes (im, ip4_af.fib_index, address,
+	ip4_del_interface_routes (sw_if_index,
+				  im, ip4_af.fib_index, address,
 				  address_length);
       else
 	ip4_add_interface_routes (sw_if_index,
@@ -712,7 +866,8 @@ ip4_sw_interface_admin_up_down (vnet_main_t * vnm, u32 sw_if_index, u32 flags)
 				im, fib_index,
 				ia);
     else
-      ip4_del_interface_routes (im, fib_index,
+      ip4_del_interface_routes (sw_if_index,
+				im, fib_index,
 				a, ia->address_length);
   }));
   /* *INDENT-ON* */
diff --git a/src/vnet/ip/ip6_forward.c b/src/vnet/ip/ip6_forward.c
index b990d7c45d2..fbdf0b9b5a0 100644
--- a/src/vnet/ip/ip6_forward.c
+++ b/src/vnet/ip/ip6_forward.c
@@ -60,22 +60,53 @@
 #define OI_DECAP   0x80000000
 
 static void
-ip6_add_interface_routes (vnet_main_t * vnm, u32 sw_if_index,
-			  ip6_main_t * im, u32 fib_index,
-			  ip_interface_address_t * a)
+ip6_add_interface_prefix_routes (ip6_main_t * im,
+				 u32 sw_if_index,
+				 u32 fib_index,
+				 ip6_address_t * address, u32 address_length)
 {
   ip_lookup_main_t *lm = &im->lookup_main;
-  ip6_address_t *address = ip_interface_address_get_address (lm, a);
-  fib_prefix_t pfx = {
-    .fp_len = a->address_length,
-    .fp_proto = FIB_PROTOCOL_IP6,
-    .fp_addr.ip6 = *address,
+  ip_interface_prefix_t *if_prefix;
+
+  ip_interface_prefix_key_t key = {
+    .prefix = {
+	       .fp_len = address_length,
+	       .fp_proto = FIB_PROTOCOL_IP6,
+	       .fp_addr.ip6 = {
+			       .as_u64 = {
+					  address->as_u64[0] &
+					  im->fib_masks[address_length].
+					  as_u64[0],
+					  address->
+					  as_u64[1] &
+					  im->fib_masks[address_length].
+					  as_u64[1],
+					  },
+			       },
+	       },
+    .sw_if_index = sw_if_index,
   };
 
-  if (a->address_length < 128)
+  /* If prefix already set on interface, just increment ref count & return */
+  if_prefix = ip_get_interface_prefix (lm, &key);
+  if (if_prefix)
+    {
+      if_prefix->ref_count += 1;
+      return;
+    }
+
+  /* New prefix - allocate a pool entry, initialize it, add to the hash */
+  pool_get (lm->if_prefix_pool, if_prefix);
+  if_prefix->ref_count = 1;
+  clib_memcpy (&if_prefix->key, &key, sizeof (key));
+  mhash_set (&lm->prefix_to_if_prefix_index, &key,
+	     if_prefix - lm->if_prefix_pool, 0 /* old value */ );
+
+  /* length < 128 - add glean */
+  if (address_length < 128)
     {
-      fib_table_entry_update_one_path (fib_index,
-				       &pfx,
+      /* set the glean route for the prefix */
+      fib_table_entry_update_one_path (fib_index, &key.prefix,
 				       FIB_SOURCE_INTERFACE,
 				       (FIB_ENTRY_FLAG_CONNECTED |
 					FIB_ENTRY_FLAG_ATTACHED),
@@ -84,9 +115,27 @@ ip6_add_interface_routes (vnet_main_t * vnm, u32 sw_if_index,
 				       NULL, sw_if_index,
 				       /* invalid FIB index */
 				       ~0, 1,
-				       /* no label stack */
+				       /* no out-label stack */
 				       NULL, FIB_ROUTE_PATH_FLAG_NONE);
     }
+}
+
+static void
+ip6_add_interface_routes (vnet_main_t * vnm, u32 sw_if_index,
+			  ip6_main_t * im, u32 fib_index,
+			  ip_interface_address_t * a)
+{
+  ip_lookup_main_t *lm = &im->lookup_main;
+  ip6_address_t *address = ip_interface_address_get_address (lm, a);
+  fib_prefix_t pfx = {
+    .fp_len = a->address_length,
+    .fp_proto = FIB_PROTOCOL_IP6,
+    .fp_addr.ip6 = *address,
+  };
+
+  /* set special routes for the prefix if needed */
+  ip6_add_interface_prefix_routes (im, sw_if_index, fib_index,
+				   address, a->address_length);
 
   pfx.fp_len = 128;
   if (sw_if_index < vec_len (lm->classify_table_index_by_sw_if_index))
@@ -121,23 +170,73 @@ ip6_add_interface_routes (vnet_main_t * vnm, u32 sw_if_index,
 }
 
 static void
-ip6_del_interface_routes (ip6_main_t * im,
+ip6_del_interface_prefix_routes (ip6_main_t * im,
+				 u32 sw_if_index,
+				 u32 fib_index,
+				 ip6_address_t * address, u32 address_length)
+{
+  ip_lookup_main_t *lm = &im->lookup_main;
+  ip_interface_prefix_t *if_prefix;
+
+  ip_interface_prefix_key_t key = {
+    .prefix = {
+	       .fp_len = address_length,
+	       .fp_proto = FIB_PROTOCOL_IP6,
+	       .fp_addr.ip6 = {
+			       .as_u64 = {
+					  address->as_u64[0] &
+					  im->fib_masks[address_length].
+					  as_u64[0],
+					  address->
+					  as_u64[1] &
+					  im->fib_masks[address_length].
+					  as_u64[1],
+					  },
+			       },
+	       },
+    .sw_if_index = sw_if_index,
+  };
+
+  if_prefix = ip_get_interface_prefix (lm, &key);
+  if (!if_prefix)
+    {
+      clib_warning ("Prefix not found while deleting %U",
+		    format_ip4_address_and_length, address, address_length);
+      return;
+    }
+
+  /* If not deleting last intf addr in prefix, decrement ref count & return */
+  if_prefix->ref_count -= 1;
+  if (if_prefix->ref_count > 0)
+    return;
+
+  /* length <= 30, delete glean route */
+  if (address_length <= 128)
+    {
+      /* remove glean route for prefix */
+      fib_table_entry_delete (fib_index, &key.prefix, FIB_SOURCE_INTERFACE);
+
+    }
+
+  mhash_unset (&lm->prefix_to_if_prefix_index, &key, 0 /* old_value */ );
+  pool_put (lm->if_prefix_pool, if_prefix);
+}
+
+static void
+ip6_del_interface_routes (u32 sw_if_index, ip6_main_t * im,
 			  u32 fib_index,
 			  ip6_address_t * address, u32 address_length)
 {
   fib_prefix_t pfx = {
-    .fp_len = address_length,
+    .fp_len = 128,
     .fp_proto = FIB_PROTOCOL_IP6,
     .fp_addr.ip6 = *address,
   };
 
-  if (pfx.fp_len < 128)
-    {
-      fib_table_entry_delete (fib_index, &pfx, FIB_SOURCE_INTERFACE);
-
-    }
+  /* delete special routes for the prefix if needed */
+  ip6_del_interface_prefix_routes (im, sw_if_index, fib_index,
+				   address, address_length);
 
-  pfx.fp_len = 128;
   fib_table_entry_delete (fib_index, &pfx, FIB_SOURCE_INTERFACE);
 }
 
@@ -278,6 +377,13 @@ ip6_add_del_interface_address (vlib_main_t * vm,
                                                       address,
                                                       address_length))
                      {
+		       /* an intf may have >1 addr from the same prefix */
+		       if ((sw_if_index == sif->sw_if_index) &&
+			   (ia->address_length == address_length) &&
+			   !ip6_address_is_equal (x, address))
+		         continue;
+
+		       /* error if the length or intf was different */
                        vnm->api_errno = VNET_API_ERROR_DUPLICATE_IF_ADDRESS;
                        return
                          clib_error_create
@@ -311,7 +417,8 @@ ip6_add_del_interface_address (vlib_main_t * vm,
   ip6_sw_interface_enable_disable (sw_if_index, !is_del);
 
   if (is_del)
-    ip6_del_interface_routes (im, ip6_af.fib_index, address, address_length);
+    ip6_del_interface_routes (sw_if_index,
+			      im, ip6_af.fib_index, address, address_length);
   else
     ip6_add_interface_routes (vnm, sw_if_index,
 			      im, ip6_af.fib_index,
@@ -361,7 +468,7 @@ ip6_sw_interface_admin_up_down (vnet_main_t * vnm, u32 sw_if_index, u32 flags)
 				im, fib_index,
 				ia);
     else
-      ip6_del_interface_routes (im, fib_index,
+      ip6_del_interface_routes (sw_if_index, im, fib_index,
 				a, ia->address_length);
   }));
   /* *INDENT-ON* */
diff --git a/src/vnet/ip/lookup.c b/src/vnet/ip/lookup.c
index 8c89ed4f490..60cedac57d8 100644
--- a/src/vnet/ip/lookup.c
+++ b/src/vnet/ip/lookup.c
@@ -207,6 +207,8 @@ ip_lookup_init (ip_lookup_main_t * lm, u32 is_ip6)
     lm->fib_result_n_bytes = sizeof (uword);
 
   lm->is_ip6 = is_ip6;
+  mhash_init (&lm->prefix_to_if_prefix_index, sizeof (uword),
+	      sizeof (ip_interface_prefix_key_t));
   if (is_ip6)
     {
       lm->format_address_and_length = format_ip6_address_and_length;
diff --git a/src/vnet/ip/lookup.h b/src/vnet/ip/lookup.h
index 4c598e3a460..6340e57e095 100644
--- a/src/vnet/ip/lookup.h
+++ b/src/vnet/ip/lookup.h
@@ -86,6 +86,24 @@ typedef u32 flow_hash_config_t;
 /* An all zeros address */
 extern const ip46_address_t zero_addr;
 
+typedef struct
+{
+  fib_prefix_t prefix;
+
+  u32 sw_if_index;
+} ip_interface_prefix_key_t;
+
+typedef struct
+{
+  /* key - prefix and sw_if_index */
+  ip_interface_prefix_key_t key;
+
+  /* number of addresses in this prefix on the interface */
+  u16 ref_count;
+
+  /* index of the interface address used as a default source address */
+  u32 src_ia_index;
+} ip_interface_prefix_t;
 
 typedef struct
 {
@@ -131,6 +149,12 @@ typedef struct ip_lookup_main_t
      ~0 means this interface has no address. */
   u32 *if_address_pool_index_by_sw_if_index;
 
+  /** Pool of prefixes containing addresses assigned to interfaces */
+  ip_interface_prefix_t *if_prefix_pool;
+
+  /** Hash table mapping prefix to index in interface prefix pool */
+  mhash_t prefix_to_if_prefix_index;
+
   /** First table index to use for this interface, ~0 => none */
   u32 *classify_table_index_by_sw_if_index;
 
@@ -178,6 +202,13 @@ ip_interface_address_get_address (ip_lookup_main_t * lm,
   return mhash_key_to_mem (&lm->address_to_if_address_index, a->address_key);
 }
 
+always_inline ip_interface_prefix_t *
+ip_get_interface_prefix (ip_lookup_main_t * lm, ip_interface_prefix_key_t * k)
+{
+  uword *p = mhash_get (&lm->prefix_to_if_prefix_index, k);
+  return p ? pool_elt_at_index (lm->if_prefix_pool, p[0]) : 0;
+}
+
 /* *INDENT-OFF* */
 #define foreach_ip_interface_address(lm,a,sw_if_index,loop,body)        \
 do {                                                                    \
diff --git a/test/test_ip4.py b/test/test_ip4.py
index a6920f8dba5..0923771200e 100644
--- a/test/test_ip4.py
+++ b/test/test_ip4.py
@@ -15,7 +15,9 @@ from framework import VppTestCase, VppTestRunner
 from util import ppp
 from vpp_ip_route import VppIpRoute, VppRoutePath, VppIpMRoute, \
     VppMRoutePath, MRouteItfFlags, MRouteEntryFlags, VppMplsIpBind, \
-    VppMplsTable, VppIpTable, FibPathType, find_route
+    VppMplsTable, VppIpTable, FibPathType, find_route, \
+    VppIpInterfaceAddress
+from vpp_ip import VppIpAddress
 from vpp_sub_interface import VppSubInterface, VppDot1QSubint, VppDot1ADSubint
 from vpp_papi import VppEnum
 
@@ -210,19 +212,19 @@ class TestIPv4(VppTestCase):
             self.verify_capture(i, pkts)
 
 
-class TestIPV4IfAddrRoute(VppTestCase):
+class TestIPv4IfAddrRoute(VppTestCase):
     """ IPv4 Interface Addr Route Test Case """
 
     @classmethod
     def setUpClass(cls):
-        super(TestIPV4IfAddrRoute, cls).setUpClass()
+        super(TestIPv4IfAddrRoute, cls).setUpClass()
 
     @classmethod
     def tearDownClass(cls):
-        super(TestIPV4IfAddrRoute, cls).tearDownClass()
+        super(TestIPv4IfAddrRoute, cls).tearDownClass()
 
     def setUp(self):
-        super(TestIPV4IfAddrRoute, self).setUp()
+        super(TestIPv4IfAddrRoute, self).setUp()
 
         # create 1 pg interface
         self.create_pg_interfaces(range(1))
@@ -233,11 +235,62 @@ class TestIPV4IfAddrRoute(VppTestCase):
             i.resolve_arp()
 
     def tearDown(self):
-        super(TestIPV4IfAddrRoute, self).tearDown()
+        super(TestIPv4IfAddrRoute, self).tearDown()
         for i in self.pg_interfaces:
             i.unconfig_ip4()
             i.admin_down()
 
+    def test_ipv4_ifaddrs_same_prefix(self):
+        """ IPv4 Interface Addresses Same Prefix test
+
+        Test scenario:
+
+            - Verify no route in FIB for prefix 10.10.10.0/24
+            - Configure IPv4 address 10.10.10.10/24 on an interface
+            - Verify route in FIB for prefix 10.10.10.0/24
+            - Configure IPv4 address 10.10.10.20/24 on an interface
+            - Delete 10.10.10.10/24 from interface
+            - Verify route in FIB for prefix 10.10.10.0/24
+            - Delete 10.10.10.20/24 from interface
+            - Verify no route in FIB for prefix 10.10.10.0/24
+        """
+
+        # create two addresses, verify route not present
+        if_addr1 = VppIpInterfaceAddress(self, self.pg0,
+                                         VppIpAddress("10.10.10.10"), 24)
+        if_addr2 = VppIpInterfaceAddress(self, self.pg0,
+                                         VppIpAddress("10.10.10.20"), 24)
+        self.assertFalse(if_addr1.query_vpp_config())  # 10.10.10.0/24
+        self.assertFalse(find_route(self, "10.10.10.10", 32))
+        self.assertFalse(find_route(self, "10.10.10.20", 32))
+        self.assertFalse(find_route(self, "10.10.10.255", 32))
+        self.assertFalse(find_route(self, "10.10.10.0", 32))
+
+        # configure first address, verify route present
+        if_addr1.add_vpp_config()
+        self.assertTrue(if_addr1.query_vpp_config())  # 10.10.10.0/24
+        self.assertTrue(find_route(self, "10.10.10.10", 32))
+        self.assertFalse(find_route(self, "10.10.10.20", 32))
+        self.assertTrue(find_route(self, "10.10.10.255", 32))
+        self.assertTrue(find_route(self, "10.10.10.0", 32))
+
+        # configure second address, delete first, verify route not removed
+        if_addr2.add_vpp_config()
+        if_addr1.remove_vpp_config()
+        self.assertTrue(if_addr1.query_vpp_config())  # 10.10.10.0/24
+        self.assertFalse(find_route(self, "10.10.10.10", 32))
+        self.assertTrue(find_route(self, "10.10.10.20", 32))
+        self.assertTrue(find_route(self, "10.10.10.255", 32))
+        self.assertTrue(find_route(self, "10.10.10.0", 32))
+
+        # delete second address, verify route removed
+        if_addr2.remove_vpp_config()
+        self.assertFalse(if_addr1.query_vpp_config())  # 10.10.10.0/24
+        self.assertFalse(find_route(self, "10.10.10.10", 32))
+        self.assertFalse(find_route(self, "10.10.10.20", 32))
+        self.assertFalse(find_route(self, "10.10.10.255", 32))
+        self.assertFalse(find_route(self, "10.10.10.0", 32))
+
     def test_ipv4_ifaddr_route(self):
         """ IPv4 Interface Address Route test
 
diff --git a/test/test_ip6.py b/test/test_ip6.py
index f8295513516..f2c4c00424e 100644
--- a/test/test_ip6.py
+++ b/test/test_ip6.py
@@ -20,10 +20,11 @@ from six import moves
 
 from framework import VppTestCase, VppTestRunner
 from util import ppp, ip6_normalize, mk_ll_addr
-from vpp_ip import DpoProto
+from vpp_ip import DpoProto, VppIpAddress
 from vpp_ip_route import VppIpRoute, VppRoutePath, find_route, VppIpMRoute, \
     VppMRoutePath, MRouteItfFlags, MRouteEntryFlags, VppMplsIpBind, \
-    VppMplsRoute, VppMplsTable, VppIpTable, FibPathType
+    VppMplsRoute, VppMplsTable, VppIpTable, FibPathType, \
+    VppIpInterfaceAddress
 from vpp_neighbor import find_nbr, VppNeighbor
 from vpp_pg_interface import is_ipv6_misc
 from vpp_sub_interface import VppSubInterface, VppDot1QSubint
@@ -935,6 +936,80 @@ class TestIPv6(TestIPv6ND):
         self.pg0.ip6_ra_config(no=1, suppress=1, send_unicast=0)
 
 
+class TestIPv6IfAddrRoute(VppTestCase):
+    """ IPv6 Interface Addr Route Test Case """
+
+    @classmethod
+    def setUpClass(cls):
+        super(TestIPv6IfAddrRoute, cls).setUpClass()
+
+    @classmethod
+    def tearDownClass(cls):
+        super(TestIPv6IfAddrRoute, cls).tearDownClass()
+
+    def setUp(self):
+        super(TestIPv6IfAddrRoute, self).setUp()
+
+        # create 1 pg interface
+        self.create_pg_interfaces(range(1))
+
+        for i in self.pg_interfaces:
+            i.admin_up()
+            i.config_ip6()
+            i.resolve_ndp()
+
+    def tearDown(self):
+        super(TestIPv6IfAddrRoute, self).tearDown()
+        for i in self.pg_interfaces:
+            i.unconfig_ip6()
+            i.admin_down()
+
+    def test_ipv6_ifaddrs_same_prefix(self):
+        """ IPv6 Interface Addresses Same Prefix test
+
+        Test scenario:
+
+            - Verify no route in FIB for prefix 2001:10::/64
+            - Configure IPv4 address 2001:10::10/64  on an interface
+            - Verify route in FIB for prefix 2001:10::/64
+            - Configure IPv4 address 2001:10::20/64 on an interface
+            - Delete 2001:10::10/64 from interface
+            - Verify route in FIB for prefix 2001:10::/64
+            - Delete 2001:10::20/64 from interface
+            - Verify no route in FIB for prefix 2001:10::/64
+        """
+
+        addr1 = "2001:10::10"
+        addr2 = "2001:10::20"
+
+        if_addr1 = VppIpInterfaceAddress(self, self.pg0,
+                                         VppIpAddress(addr1), 64)
+        if_addr2 = VppIpInterfaceAddress(self, self.pg0,
+                                         VppIpAddress(addr2), 64)
+        self.assertFalse(if_addr1.query_vpp_config())  # 2001:10::/64
+        self.assertFalse(find_route(self, addr1, 128))
+        self.assertFalse(find_route(self, addr2, 128))
+
+        # configure first address, verify route present
+        if_addr1.add_vpp_config()
+        self.assertTrue(if_addr1.query_vpp_config())  # 2001:10::/64
+        self.assertTrue(find_route(self, addr1, 128))
+        self.assertFalse(find_route(self, addr2, 128))
+
+        # configure second address, delete first, verify route not removed
+        if_addr2.add_vpp_config()
+        if_addr1.remove_vpp_config()
+        self.assertTrue(if_addr1.query_vpp_config())  # 2001:10::/64
+        self.assertFalse(find_route(self, addr1, 128))
+        self.assertTrue(find_route(self, addr2, 128))
+
+        # delete second address, verify route removed
+        if_addr2.remove_vpp_config()
+        self.assertFalse(if_addr1.query_vpp_config())  # 2001:10::/64
+        self.assertFalse(find_route(self, addr1, 128))
+        self.assertFalse(find_route(self, addr2, 128))
+
+
 class TestICMPv6Echo(VppTestCase):
     """ ICMPv6 Echo Test Case """