1 files changed, 25 insertions, 4 deletions

diff --git a/zebra/zapi_msg.c b/zebra/zapi_msg.c
index c0882c3f35..2190bfab4f 100644
--- a/zebra/zapi_msg.c
+++ b/zebra/zapi_msg.c
@@ -383,9 +383,14 @@ static void zebra_interface_nbr_address_add_update(struct interface *ifp,
 			p->prefixlen, ifc->ifp->name);
 	}
 
-	for (ALL_LIST_ELEMENTS(zrouter.client_list, node, nnode, client))
+	for (ALL_LIST_ELEMENTS(zrouter.client_list, node, nnode, client)) {
+		/* Do not send unsolicited messages to synchronous clients. */
+		if (client->synchronous)
+			continue;
+
 		zsend_interface_nbr_address(ZEBRA_INTERFACE_NBR_ADDRESS_ADD,
 					    client, ifp, ifc);
+	}
 }
 
 /* Interface address deletion. */
@@ -407,9 +412,14 @@ static void zebra_interface_nbr_address_delete_update(struct interface *ifp,
 			p->prefixlen, ifc->ifp->name);
 	}
 
-	for (ALL_LIST_ELEMENTS(zrouter.client_list, node, nnode, client))
+	for (ALL_LIST_ELEMENTS(zrouter.client_list, node, nnode, client)) {
+		/* Do not send unsolicited messages to synchronous clients. */
+		if (client->synchronous)
+			continue;
+
 		zsend_interface_nbr_address(ZEBRA_INTERFACE_NBR_ADDRESS_DELETE,
 					    client, ifp, ifc);
+	}
 }
 
 /* Send addresses on interface to client */
@@ -1740,6 +1750,10 @@ void zsend_capabilities_all_clients(void)
 
 	zvrf = vrf_info_lookup(VRF_DEFAULT);
 	for (ALL_LIST_ELEMENTS(zrouter.client_list, node, nnode, client)) {
+		/* Do not send unsolicited messages to synchronous clients. */
+		if (client->synchronous)
+			continue;
+
 		zsend_capabilities(client, zvrf);
 	}
 }
@@ -1751,13 +1765,18 @@ static void zread_hello(ZAPI_HANDLER_ARGS)
 	uint8_t proto;
 	unsigned short instance;
 	uint8_t notify;
+	uint8_t synchronous;
 
 	STREAM_GETC(msg, proto);
 	STREAM_GETW(msg, instance);
 	STREAM_GETC(msg, notify);
+	STREAM_GETC(msg, synchronous);
 	if (notify)
 		client->notify_owner = true;
 
+	if (synchronous)
+		client->synchronous = true;
+
 	/* accept only dynamic routing protocols */
 	if ((proto < ZEBRA_ROUTE_MAX) && (proto > ZEBRA_ROUTE_CONNECT)) {
 		zlog_notice(
@@ -1774,8 +1793,10 @@ static void zread_hello(ZAPI_HANDLER_ARGS)
 		zebra_gr_client_reconnect(client);
 	}
 
-	zsend_capabilities(client, zvrf);
-	zebra_vrf_update_all(client);
+	if (!client->synchronous) {
+		zsend_capabilities(client, zvrf);
+		zebra_vrf_update_all(client);
+	}
 stream_failure:
 	return;
 }