l2: add per bridge domain learn limit

Type: feature

Signed-off-by: Jerome Tollet <jtollet@cisco.com>
Change-Id: I57ed6699050445d9c9aec98eff3aab56735aca54
Signed-off-by: Jerome Tollet <jtollet@cisco.com>

7 files changed, 290 insertions, 60 deletions

diff --git a/src/vnet/l2/l2.api b/src/vnet/l2/l2.api
index 416874d94c2..ef830827e1c 100644
--- a/src/vnet/l2/l2.api
+++ b/src/vnet/l2/l2.api
@@ -247,6 +247,33 @@ autoreply define bridge_domain_set_mac_age
   u8 mac_age;
 };
 
+/** \brief L2 bridge domain set default learn limit
+    @param client_index - opaque cookie to identify the sender
+    @param context - sender context, to match reply w/ request
+    @param learn limit - maximum number of entries by default for bridge domains
+*/
+autoreply define bridge_domain_set_default_learn_limit
+{
+  u32 client_index;
+  u32 context;
+  u32 learn_limit;
+};
+
+
+/** \brief L2 bridge domain set learn limit
+    @param client_index - opaque cookie to identify the sender
+    @param context - sender context, to match reply w/ request
+    @param bd_id - the bridge domain idenntifier
+    @param learn limit - maximum number of entries for this bd
+*/
+autoreply define bridge_domain_set_learn_limit
+{
+  u32 client_index;
+  u32 context;
+  u32 bd_id;
+  u32 learn_limit;
+};
+
 /** \brief L2 bridge domain add or delete request
     @param client_index - opaque cookie to identify the sender
     @param context - sender context, to match reply w/ request
diff --git a/src/vnet/l2/l2_api.c b/src/vnet/l2/l2_api.c
index 2c2f480b35f..97b429d0498 100644
--- a/src/vnet/l2/l2_api.c
+++ b/src/vnet/l2/l2_api.c
@@ -50,33 +50,36 @@
 
 #include <vlibapi/api_helper_macros.h>
 
-#define foreach_vpe_api_msg                                 \
-_(L2_XCONNECT_DUMP, l2_xconnect_dump)                       \
-_(L2_FIB_CLEAR_TABLE, l2_fib_clear_table)                   \
-_(L2_FIB_TABLE_DUMP, l2_fib_table_dump)                     \
-_(L2FIB_FLUSH_ALL, l2fib_flush_all)                         \
-_(L2FIB_FLUSH_INT, l2fib_flush_int)                         \
-_(L2FIB_FLUSH_BD, l2fib_flush_bd)                           \
-_(L2FIB_ADD_DEL, l2fib_add_del)                             \
-_(WANT_L2_MACS_EVENTS, want_l2_macs_events)		    \
-_(L2_FLAGS, l2_flags)                                       \
-_(SW_INTERFACE_SET_L2_XCONNECT, sw_interface_set_l2_xconnect)   \
-_(SW_INTERFACE_SET_L2_BRIDGE, sw_interface_set_l2_bridge)       \
-_(L2_PATCH_ADD_DEL, l2_patch_add_del)				\
-_(L2_INTERFACE_EFP_FILTER, l2_interface_efp_filter)             \
-_(BD_IP_MAC_ADD_DEL, bd_ip_mac_add_del)                         \
-_(BD_IP_MAC_FLUSH, bd_ip_mac_flush)                             \
-_(BD_IP_MAC_DUMP, bd_ip_mac_dump)				\
-_(BRIDGE_DOMAIN_ADD_DEL, bridge_domain_add_del)                 \
-_(BRIDGE_DOMAIN_DUMP, bridge_domain_dump)                       \
-_(BRIDGE_FLAGS, bridge_flags)                                   \
-_(L2_INTERFACE_VLAN_TAG_REWRITE, l2_interface_vlan_tag_rewrite) \
-_(L2_INTERFACE_PBB_TAG_REWRITE, l2_interface_pbb_tag_rewrite)   \
-_(BRIDGE_DOMAIN_SET_MAC_AGE, bridge_domain_set_mac_age)         \
-_(SW_INTERFACE_SET_VPATH, sw_interface_set_vpath)               \
-_(BVI_CREATE, bvi_create)                                       \
-_(BVI_DELETE, bvi_delete)                                       \
-_(WANT_L2_ARP_TERM_EVENTS, want_l2_arp_term_events)
+#define foreach_vpe_api_msg                                                   \
+  _ (L2_XCONNECT_DUMP, l2_xconnect_dump)                                      \
+  _ (L2_FIB_CLEAR_TABLE, l2_fib_clear_table)                                  \
+  _ (L2_FIB_TABLE_DUMP, l2_fib_table_dump)                                    \
+  _ (L2FIB_FLUSH_ALL, l2fib_flush_all)                                        \
+  _ (L2FIB_FLUSH_INT, l2fib_flush_int)                                        \
+  _ (L2FIB_FLUSH_BD, l2fib_flush_bd)                                          \
+  _ (L2FIB_ADD_DEL, l2fib_add_del)                                            \
+  _ (WANT_L2_MACS_EVENTS, want_l2_macs_events)                                \
+  _ (L2_FLAGS, l2_flags)                                                      \
+  _ (SW_INTERFACE_SET_L2_XCONNECT, sw_interface_set_l2_xconnect)              \
+  _ (SW_INTERFACE_SET_L2_BRIDGE, sw_interface_set_l2_bridge)                  \
+  _ (L2_PATCH_ADD_DEL, l2_patch_add_del)                                      \
+  _ (L2_INTERFACE_EFP_FILTER, l2_interface_efp_filter)                        \
+  _ (BD_IP_MAC_ADD_DEL, bd_ip_mac_add_del)                                    \
+  _ (BD_IP_MAC_FLUSH, bd_ip_mac_flush)                                        \
+  _ (BD_IP_MAC_DUMP, bd_ip_mac_dump)                                          \
+  _ (BRIDGE_DOMAIN_ADD_DEL, bridge_domain_add_del)                            \
+  _ (BRIDGE_DOMAIN_DUMP, bridge_domain_dump)                                  \
+  _ (BRIDGE_FLAGS, bridge_flags)                                              \
+  _ (L2_INTERFACE_VLAN_TAG_REWRITE, l2_interface_vlan_tag_rewrite)            \
+  _ (L2_INTERFACE_PBB_TAG_REWRITE, l2_interface_pbb_tag_rewrite)              \
+  _ (BRIDGE_DOMAIN_SET_MAC_AGE, bridge_domain_set_mac_age)                    \
+  _ (SW_INTERFACE_SET_VPATH, sw_interface_set_vpath)                          \
+  _ (BVI_CREATE, bvi_create)                                                  \
+  _ (BVI_DELETE, bvi_delete)                                                  \
+  _ (WANT_L2_ARP_TERM_EVENTS, want_l2_arp_term_events)                        \
+  _ (BRIDGE_DOMAIN_SET_LEARN_LIMIT, bridge_domain_set_learn_limit)            \
+  _ (BRIDGE_DOMAIN_SET_DEFAULT_LEARN_LIMIT,                                   \
+     bridge_domain_set_default_learn_limit)
 
 static void
 send_l2_xconnect_details (vl_api_registration_t * reg, u32 context,
@@ -409,6 +412,45 @@ vl_api_l2_flags_t_handler (vl_api_l2_flags_t * mp)
 }
 
 static void
+vl_api_bridge_domain_set_default_learn_limit_t_handler (
+  vl_api_bridge_domain_set_default_learn_limit_t *mp)
+{
+  vl_api_bridge_domain_set_default_learn_limit_reply_t *rmp;
+  int rv = 0;
+
+  l2learn_main.bd_default_learn_limit = ntohl (mp->learn_limit);
+  REPLY_MACRO (VL_API_BRIDGE_DOMAIN_SET_DEFAULT_LEARN_LIMIT_REPLY);
+}
+
+static void
+vl_api_bridge_domain_set_learn_limit_t_handler (
+  vl_api_bridge_domain_set_learn_limit_t *mp)
+{
+  vlib_main_t *vm = vlib_get_main ();
+  bd_main_t *bdm = &bd_main;
+  vl_api_bridge_domain_set_learn_limit_reply_t *rmp;
+  int rv = 0;
+  u32 bd_id = ntohl (mp->bd_id);
+  uword *p;
+
+  if (bd_id == 0)
+    {
+      rv = VNET_API_ERROR_BD_NOT_MODIFIABLE;
+      goto out;
+    }
+
+  p = hash_get (bdm->bd_index_by_bd_id, bd_id);
+  if (p == 0)
+    {
+      rv = VNET_API_ERROR_NO_SUCH_ENTRY;
+      goto out;
+    }
+  bd_set_learn_limit (vm, *p, ntohl (mp->learn_limit));
+out:
+  REPLY_MACRO (VL_API_BRIDGE_DOMAIN_SET_LEARN_LIMIT_REPLY);
+}
+
+static void
 vl_api_bridge_domain_set_mac_age_t_handler (vl_api_bridge_domain_set_mac_age_t
 					    * mp)
 {
diff --git a/src/vnet/l2/l2_bd.c b/src/vnet/l2/l2_bd.c
index a3acc4b6d7e..7e6ea60b440 100644
--- a/src/vnet/l2/l2_bd.c
+++ b/src/vnet/l2/l2_bd.c
@@ -88,6 +88,9 @@ bd_add_bd_index (bd_main_t * bdm, u32 bd_id)
 
   vec_validate (l2input_main.bd_configs, rv);
   l2input_main.bd_configs[rv].bd_id = bd_id;
+  l2input_main.bd_configs[rv].learn_limit =
+    l2learn_main.bd_default_learn_limit;
+  l2input_main.bd_configs[rv].learn_count = 0;
 
   return rv;
 }
@@ -124,6 +127,8 @@ bd_delete (bd_main_t * bdm, u32 bd_index)
   /* clear BD config for reuse: bd_id to -1 and clear feature_bitmap */
   bd->bd_id = ~0;
   bd->feature_bitmap = 0;
+  bd->learn_limit = 0;
+  bd->learn_count = ~0;
 
   /* free BD tag */
   vec_free (bd->bd_tag);
@@ -356,9 +361,20 @@ bd_set_mac_age (vlib_main_t * vm, u32 bd_index, u8 age)
 }
 
 /**
-    Set the tag for the bridge domain.
+    Set learn limit for the bridge domain.
 */
+void
+bd_set_learn_limit (vlib_main_t *vm, u32 bd_index, u32 learn_limit)
+{
+  l2_bridge_domain_t *bd_config;
+  vec_validate (l2input_main.bd_configs, bd_index);
+  bd_config = vec_elt_at_index (l2input_main.bd_configs, bd_index);
+  bd_config->learn_limit = learn_limit;
+}
 
+/**
+    Set the tag for the bridge domain.
+*/
 static void
 bd_set_bd_tag (vlib_main_t * vm, u32 bd_index, u8 * bd_tag)
 {
@@ -446,6 +462,34 @@ VLIB_CLI_COMMAND (bd_learn_cli, static) = {
 };
 /* *INDENT-ON* */
 
+static clib_error_t *
+bd_default_learn_limit (vlib_main_t *vm, unformat_input_t *input,
+			vlib_cli_command_t *cmd)
+{
+  l2learn_main_t *l2m = &l2learn_main;
+  clib_error_t *error = 0;
+  u32 learn_limit;
+
+  if (!unformat (input, "%d", &learn_limit))
+    {
+      error = clib_error_return (
+	0, "expecting per bridge-domain max entry number got`%U'",
+	format_unformat_error, input);
+      goto done;
+    }
+
+  l2m->bd_default_learn_limit = learn_limit;
+
+done:
+  return error;
+}
+
+VLIB_CLI_COMMAND (bd_default_learn_limit_cli, static) = {
+  .path = "set bridge-domain default-learn-limit",
+  .short_help = "set bridge-domain default-learn-limit <maxentries>",
+  .function = bd_default_learn_limit,
+};
+
 /**
     Set bridge-domain forward enable/disable.
     The CLI format is:
@@ -818,6 +862,55 @@ VLIB_CLI_COMMAND (bd_mac_age_cli, static) = {
 };
 /* *INDENT-ON* */
 
+static clib_error_t *
+bd_learn_limit (vlib_main_t *vm, unformat_input_t *input,
+		vlib_cli_command_t *cmd)
+{
+  bd_main_t *bdm = &bd_main;
+  clib_error_t *error = 0;
+  u32 bd_index, bd_id;
+  u32 learn_limit;
+  uword *p;
+
+  if (!unformat (input, "%d", &bd_id))
+    {
+      error = clib_error_return (0, "expecting bridge-domain id but got `%U'",
+				 format_unformat_error, input);
+      goto done;
+    }
+
+  if (bd_id == 0)
+    return clib_error_return (
+      0, "No operations on the default bridge domain are supported");
+
+  p = hash_get (bdm->bd_index_by_bd_id, bd_id);
+
+  if (p == 0)
+    return clib_error_return (0, "No such bridge domain %d", bd_id);
+
+  bd_index = p[0];
+
+  if (!unformat (input, "%u", &learn_limit))
+    {
+      error = clib_error_return (
+	0, "expecting maxium number of learned entries but got `%U'",
+	format_unformat_error, input);
+      goto done;
+    }
+
+  bd_set_learn_limit (vm, bd_index, learn_limit);
+
+done:
+  return error;
+}
+
+VLIB_CLI_COMMAND (bd_learn_limit_cli, static) = {
+  .path = "set bridge-domain learn-limit",
+  .short_help =
+    "set bridge-domain learn-limit <bridge-domain-id> <learn-limit>",
+  .function = bd_learn_limit,
+};
+
 /*?
  * Modify whether or not an existing bridge-domain should terminate and respond
  * to ARP Requests. ARP Termination is disabled by default.
@@ -1121,10 +1214,11 @@ bd_show (vlib_main_t * vm, unformat_input_t * input, vlib_cli_command_t * cmd)
 	    {
 	      printed = 1;
 	      vlib_cli_output (vm,
-			       "%=8s %=7s %=4s %=9s %=9s %=9s %=11s %=9s %=9s %=9s %=11s",
-			       "BD-ID", "Index", "BSN", "Age(min)",
-			       "Learning", "U-Forwrd", "UU-Flood",
-			       "Flooding", "ARP-Term", "arp-ufwd",
+			       "%=8s %=7s %=4s %=9s %=9s %=9s %=11s %=9s %=9s "
+			       "%=9s %=8s %=8s %=11s",
+			       "BD-ID", "Index", "BSN", "Age(min)", "Learning",
+			       "U-Forwrd", "UU-Flood", "Flooding", "ARP-Term",
+			       "arp-ufwd", "Learn-count", "Learn-limit",
 			       "BVI-Intf");
 	    }
 
@@ -1132,24 +1226,23 @@ bd_show (vlib_main_t * vm, unformat_input_t * input, vlib_cli_command_t * cmd)
 	    as = format (as, "%d", bd_config->mac_age);
 	  else
 	    as = format (as, "off");
-	  vlib_cli_output (vm,
-			   "%=8d %=7d %=9v %=9s %=9s %=11U %=9s %=9s %=9s %=11U",
-			   bd_config->bd_id, bd_index, as,
-			   bd_config->feature_bitmap & L2INPUT_FEAT_LEARN ?
-			   "on" : "off",
-			   bd_config->feature_bitmap & L2INPUT_FEAT_FWD ?
-			   "on" : "off",
-			   format_uu_cfg, bd_config,
-			   bd_config->feature_bitmap & L2INPUT_FEAT_FLOOD ?
-			   "on" : "off",
-			   bd_config->feature_bitmap & L2INPUT_FEAT_ARP_TERM ?
-			   "on" : "off",
-			   bd_config->feature_bitmap & L2INPUT_FEAT_ARP_UFWD ?
-			   "on" : "off",
-			   format_vnet_sw_if_index_name_with_NA,
-			   vnm, bd_config->bvi_sw_if_index);
-	  vlib_cli_output (vm, "%U", format_l2_input_feature_bitmap,
-			   bd_config->feature_bitmap);
+	  vlib_cli_output (
+	    vm,
+	    "%=8d %=7d %=4d %=9v %=9s %=9s %=11U %=9s %=9s %=9s %=8d %=8d "
+	    "%=11U",
+	    bd_config->bd_id, bd_index, bd_config->seq_num, as,
+	    bd_config->feature_bitmap & L2INPUT_FEAT_LEARN ? "on" : "off",
+	    bd_config->feature_bitmap & L2INPUT_FEAT_FWD ? "on" : "off",
+	    format_uu_cfg, bd_config,
+	    bd_config->feature_bitmap & L2INPUT_FEAT_FLOOD ? "on" : "off",
+	    bd_config->feature_bitmap & L2INPUT_FEAT_ARP_TERM ? "on" : "off",
+	    bd_config->feature_bitmap & L2INPUT_FEAT_ARP_UFWD ? "on" : "off",
+	    bd_config->learn_count, bd_config->learn_limit,
+	    format_vnet_sw_if_index_name_with_NA, vnm,
+	    bd_config->bvi_sw_if_index);
+	  if (detail)
+	    vlib_cli_output (vm, "%U", format_l2_input_feature_bitmap,
+			     bd_config->feature_bitmap);
 	  vec_reset_length (as);
 
 	  if (detail || intf)
@@ -1326,6 +1419,8 @@ bd_add_del (l2_bridge_domain_add_del_args_t * a)
       if (a->bd_tag)
 	bd_set_bd_tag (vm, bd_index, a->bd_tag);
 
+      bd_set_learn_limit (vm, bd_index, l2learn_main.bd_default_learn_limit);
+      vec_elt_at_index (l2input_main.bd_configs, bd_index)->learn_count = 0;
     }
   else
     {
diff --git a/src/vnet/l2/l2_bd.h b/src/vnet/l2/l2_bd.h
index 943358b4e15..0d77292519d 100644
--- a/src/vnet/l2/l2_bd.h
+++ b/src/vnet/l2/l2_bd.h
@@ -110,6 +110,12 @@ typedef struct
   /* Bridge domain tag (C string NULL terminated) */
   u8 *bd_tag;
 
+  /* Maximum number of learned entries */
+  u32 learn_limit;
+
+  /* Current number of learned entries */
+  u32 learn_count;
+
 } l2_bridge_domain_t;
 
 /* Limit Bridge Domain ID to 24 bits to match 24-bit VNI range */
@@ -158,6 +164,7 @@ typedef enum bd_flags_t_
 u32 bd_set_flags (vlib_main_t * vm, u32 bd_index, bd_flags_t flags,
 		  u32 enable);
 void bd_set_mac_age (vlib_main_t * vm, u32 bd_index, u8 age);
+void bd_set_learn_limit (vlib_main_t *vm, u32 bd_index, u32 learn_limit);
 int bd_add_del (l2_bridge_domain_add_del_args_t * args);
 
 /**
diff --git a/src/vnet/l2/l2_fib.c b/src/vnet/l2/l2_fib.c
index c28c23bc41c..82be6bc0341 100644
--- a/src/vnet/l2/l2_fib.c
+++ b/src/vnet/l2/l2_fib.c
@@ -212,8 +212,7 @@ l2fib_show_walk_cb (BVT (clib_bihash_kv) * kvp, void *arg)
       if (ctx->add && !l2fib_entry_result_is_set_AGE_NOT (&result))
 	return (BIHASH_WALK_CONTINUE);	/* skip learned macs */
 
-      bd_config = vec_elt_at_index (l2input_main.bd_configs,
-				    key.fields.bd_index);
+      bd_config = &vec_elt (l2input_main.bd_configs, key.fields.bd_index);
 
       if (l2fib_entry_result_is_set_AGE_NOT (&result))
 	s = format (s, "no");
@@ -384,6 +383,7 @@ void
 l2fib_clear_table (void)
 {
   l2fib_main_t *mp = &l2fib_main;
+  l2_bridge_domain_t *bd_config;
 
   if (mp->mac_table_initialized == 0)
     return;
@@ -394,6 +394,8 @@ l2fib_clear_table (void)
   BV (clib_bihash_free) (&mp->mac_table);
   l2fib_table_init ();
   l2learn_main.global_learn_count = 0;
+  vec_foreach (bd_config, l2input_main.bd_configs)
+    bd_config->learn_count = 0;
 }
 
 /** Clear all entries in L2FIB.
@@ -462,9 +464,21 @@ l2fib_add_entry (const u8 * mac, u32 bd_index,
     {
       /* decrement counter if overwriting a learned mac  */
       result.raw = kv.value;
-      if ((!l2fib_entry_result_is_set_AGE_NOT (&result))
-	  && (lm->global_learn_count))
-	lm->global_learn_count--;
+      if (!l2fib_entry_result_is_set_AGE_NOT (&result))
+	{
+	  l2_bridge_domain_t *bd_config =
+	    vec_elt_at_index (l2input_main.bd_configs, bd_index);
+
+	  /* check if learn_count == 0 in case of race condition between 2
+	   * workers adding an entry simultaneously */
+	  /* learn_count variable may have little inaccuracy because they are
+	   * not incremented/decremented with atomic operations */
+	  /* l2fib_scan is call every 2sec fixing potential inaccuracy */
+	  if (lm->global_learn_count)
+	    lm->global_learn_count--;
+	  if (bd_config->learn_count)
+	    bd_config->learn_count--;
+	}
     }
 
   /* set up result */
@@ -751,9 +765,15 @@ l2fib_del_entry (const u8 * mac, u32 bd_index, u32 sw_if_index)
     return 1;
 
   /* decrement counter if dynamically learned mac */
-  if ((!l2fib_entry_result_is_set_AGE_NOT (&result)) &&
-      (l2learn_main.global_learn_count))
-    l2learn_main.global_learn_count--;
+  if (!l2fib_entry_result_is_set_AGE_NOT (&result))
+    {
+      l2_bridge_domain_t *bd_config =
+	vec_elt_at_index (l2input_main.bd_configs, bd_index);
+      if (l2learn_main.global_learn_count)
+	l2learn_main.global_learn_count--;
+      if (bd_config->learn_count)
+	bd_config->learn_count--;
+    }
 
   /* Remove entry from hash table */
   BV (clib_bihash_add_del) (&mp->mac_table, &kv, 0 /* is_add */ );
@@ -1051,11 +1071,16 @@ l2fib_scan (vlib_main_t * vm, f64 start_time, u8 event_only)
   u32 cl_idx = lm->client_index;
   vl_api_l2_macs_event_t *mp = 0;
   vl_api_registration_t *reg = 0;
+  u32 bd_index;
+  static u32 *bd_learn_counts = 0;
 
   /* Don't scan the l2 fib if it hasn't been instantiated yet */
   if (alloc_arena (h) == 0)
     return 0.0;
 
+  vec_reset_length (bd_learn_counts);
+  vec_validate (bd_learn_counts, vec_len (l2input_main.bd_configs) - 1);
+
   if (client)
     {
       mp = allocate_mac_evt_buf (client, cl_idx);
@@ -1069,6 +1094,9 @@ l2fib_scan (vlib_main_t * vm, f64 start_time, u8 event_only)
       if (delta_t > 20e-6)
 	{
 	  vlib_process_suspend (vm, 100e-6);	/* suspend for 100 us */
+	  /* in case a new bd was created while sleeping */
+	  vec_validate (bd_learn_counts,
+			vec_len (l2input_main.bd_configs) - 1);
 	  last_start = vlib_time_now (vm);
 	  accum_t += delta_t;
 	}
@@ -1102,7 +1130,10 @@ l2fib_scan (vlib_main_t * vm, f64 start_time, u8 event_only)
 	      l2fib_entry_result_t result = {.raw = v->kvp[k].value };
 
 	      if (!l2fib_entry_result_is_set_AGE_NOT (&result))
-		learn_count++;
+		{
+		  learn_count++;
+		  vec_elt (bd_learn_counts, key.fields.bd_index)++;
+		}
 
 	      if (client)
 		{
@@ -1190,6 +1221,7 @@ l2fib_scan (vlib_main_t * vm, f64 start_time, u8 event_only)
 	      kv.key = key.raw;
 	      BV (clib_bihash_add_del) (&fm->mac_table, &kv, 0);
 	      learn_count--;
+	      vec_elt (bd_learn_counts, key.fields.bd_index)--;
 	      /*
 	       * Note: we may have just freed the bucket's backing
 	       * storage, so check right here...
@@ -1205,6 +1237,11 @@ l2fib_scan (vlib_main_t * vm, f64 start_time, u8 event_only)
 
   /* keep learn count consistent */
   l2learn_main.global_learn_count = learn_count;
+  vec_foreach_index (bd_index, l2input_main.bd_configs)
+    {
+      vec_elt (l2input_main.bd_configs, bd_index).learn_count =
+	vec_elt (bd_learn_counts, bd_index);
+    }
 
   if (mp)
     {
diff --git a/src/vnet/l2/l2_learn.c b/src/vnet/l2/l2_learn.c
index 6f2201b3ade..3b9b1dbcaa9 100644
--- a/src/vnet/l2/l2_learn.c
+++ b/src/vnet/l2/l2_learn.c
@@ -119,6 +119,8 @@ l2learn_process (vlib_node_runtime_t * node,
 		 u32 * count,
 		 l2fib_entry_result_t * result0, u16 * next0, u8 timestamp)
 {
+  l2_bridge_domain_t *bd_config =
+    vec_elt_at_index (l2input_main.bd_configs, vnet_buffer (b0)->l2.bd_index);
   /* Set up the default next node (typically L2FWD) */
   *next0 = vnet_l2_feature_next (b0, msm->feat_next_node_index,
 				 L2INPUT_FEAT_LEARN);
@@ -137,6 +139,8 @@ l2learn_process (vlib_node_runtime_t * node,
 	return;			/* Static MAC always age_not */
       if (msm->global_learn_count > msm->global_learn_limit)
 	return;			/* Above learn limit - do not update */
+      if (bd_config->learn_count > bd_config->learn_limit)
+	return; /* Above bridge domain learn limit - do not update */
 
       /* Limit updates per l2-learn node call to avoid prolonged update burst
        * as dtime advance over 1 minute mark, unless more than 1 min behind
@@ -152,7 +156,8 @@ l2learn_process (vlib_node_runtime_t * node,
       /* Entry not in L2FIB - add it  */
       counter_base[L2LEARN_ERROR_MISS] += 1;
 
-      if (msm->global_learn_count >= msm->global_learn_limit)
+      if ((msm->global_learn_count >= msm->global_learn_limit) ||
+	  (bd_config->learn_count >= bd_config->learn_limit))
 	{
 	  /*
 	   * Global limit reached. Do not learn the mac but forward the packet.
@@ -169,7 +174,11 @@ l2learn_process (vlib_node_runtime_t * node,
 	return;
 
       /* It is ok to learn */
+      /* learn_count variable may have little inaccuracy because they are not
+       * incremented/decremented with atomic operations */
+      /* l2fib_scan is call every 2sec fixing potential inaccuracy */
       msm->global_learn_count++;
+      bd_config->learn_count++;
       result0->raw = 0;		/* clear all fields */
       result0->fields.sw_if_index = sw_if_index0;
       if (msm->client_pid != 0)
@@ -208,7 +217,12 @@ l2learn_process (vlib_node_runtime_t * node,
       if (l2fib_entry_result_is_set_AGE_NOT (result0))
 	{
 	  /* The mac was provisioned */
+	  /* learn_count variable may have little inaccuracy because they are
+	   * not incremented/decremented with atomic operations */
+	  /* l2fib_scan is call every 2sec fixing potential inaccuracy */
 	  msm->global_learn_count++;
+	  bd_config->learn_count++;
+
 	  l2fib_entry_result_clear_AGE_NOT (result0);
 	}
       if (msm->client_pid != 0)
@@ -470,6 +484,11 @@ l2learn_init (vlib_main_t * vm)
    */
   mp->global_learn_limit = L2LEARN_DEFAULT_LIMIT;
 
+  /*
+   * Set the default number of dynamically learned macs to the number
+   * of buckets.
+   */
+  mp->bd_default_learn_limit = L2LEARN_DEFAULT_LIMIT;
   return 0;
 }
 
diff --git a/src/vnet/l2/l2_learn.h b/src/vnet/l2/l2_learn.h
index eea34ee83d3..da654e628fc 100644
--- a/src/vnet/l2/l2_learn.h
+++ b/src/vnet/l2/l2_learn.h
@@ -35,6 +35,9 @@ typedef struct
   /* maximum number of dynamically learned mac entries */
   u32 global_learn_limit;
 
+  /* maximum number of dynamically learned mac entries per bridge domain */
+  u32 bd_default_learn_limit;
+
   /* client waiting for L2 MAC events for learned and aged MACs */
   u32 client_pid;
   u32 client_index;