FRRouting · AndriiFullroot · Mar 17, 2025 · Mar 25, 2025 · Mar 25, 2025
diff --git a/doc/user/ldpd.rst b/doc/user/ldpd.rst
@@ -141,6 +141,19 @@ LDP Configuration
    If GTSM is enabled, multi-hop neighbors should have either GTSM disabled
    individually or configured with an appropriate ttl-security hops distance.
 
+.. clicmd:: disable-establish-hello
+
+   Located under the MPLS address-family interface node. By default,
+   the ldpd service sends additional LDP multicast hello messages on TCP
+   session establishment. This should speed up the connection time, so
+   the "passive" service would receive the "hello" earlier and would "accept"
+   TCP without waiting for the UDP message on interval. This behaviour can
+   produce massive traffic with multicast packets if there are a lot of ldpd
+   services in one local network, essentially each "addition hello" may trigger
+   attempt for connection and sending "additional hello" from other ldpd
+   services. This option allows to disable that behaviour. LDP hello multicast
+   messages would be sent only by interval.
+
 .. clicmd:: neighbor A.B.C.D password PASSWORD
 
    The following command located under MPLS router node configures the router

diff --git a/ldpd/interface.c b/ldpd/interface.c
@@ -63,11 +63,13 @@ if_new(const char *name)
 	iface->ipv4.af = AF_INET;
 	iface->ipv4.iface = iface;
 	iface->ipv4.enabled = 0;
+	iface->ipv4.disable_establish_hello = 0;
 
 	/* ipv6 */
 	iface->ipv6.af = AF_INET6;
 	iface->ipv6.iface = iface;
 	iface->ipv6.enabled = 0;
+	iface->ipv6.disable_establish_hello = 0;
 
 	return (iface);
 }

diff --git a/ldpd/ldp_vty.h b/ldpd/ldp_vty.h
@@ -24,6 +24,7 @@ int	 ldp_vty_allow_broken_lsp(struct vty *, const char *);
 int	 ldp_vty_address_family (struct vty *, const char *, const char *);
 int	 ldp_vty_disc_holdtime(struct vty *, const char *, enum hello_type, long);
 int	 ldp_vty_disc_interval(struct vty *, const char *, enum hello_type, long);
+int	 ldp_vty_disable_establish_hello(struct vty *, const char *);
 int	 ldp_vty_targeted_hello_accept(struct vty *, const char *, const char *);
 int	 ldp_vty_nbr_session_holdtime(struct vty *, const char *, struct in_addr, long);
 int	 ldp_vty_af_session_holdtime(struct vty *, const char *, long);

diff --git a/ldpd/ldp_vty_cmds.c b/ldpd/ldp_vty_cmds.c
@@ -122,6 +122,15 @@ DEFPY  (ldp_discovery_link_interval,
 	return (ldp_vty_disc_interval(vty, no, HELLO_LINK, interval));
 }
 
+DEFPY  (ldp_disable_establish_hello,
+	ldp_disable_establish_hello_cmd,
+	"[no] disable-establish-hello",
+	NO_STR
+	"Disable sending additional LDP hello message on establishing LDP tcp connection\n")
+{
+	return ldp_vty_disable_establish_hello(vty, no);
+}
+
 DEFPY  (ldp_discovery_targeted_interval,
 	ldp_discovery_targeted_interval_cmd,
 	"[no] discovery targeted-hello interval (1-65535)$interval",
@@ -866,9 +875,11 @@ ldp_vty_init (void)
 
 	install_element(LDP_IPV4_IFACE_NODE, &ldp_discovery_link_holdtime_cmd);
 	install_element(LDP_IPV4_IFACE_NODE, &ldp_discovery_link_interval_cmd);
+	install_element(LDP_IPV4_IFACE_NODE, &ldp_disable_establish_hello_cmd);
 
 	install_element(LDP_IPV6_IFACE_NODE, &ldp_discovery_link_holdtime_cmd);
 	install_element(LDP_IPV6_IFACE_NODE, &ldp_discovery_link_interval_cmd);
+	install_element(LDP_IPV6_IFACE_NODE, &ldp_disable_establish_hello_cmd);
 
 	install_element(LDP_L2VPN_NODE, &ldp_bridge_cmd);
 	install_element(LDP_L2VPN_NODE, &ldp_mtu_cmd);

diff --git a/ldpd/ldp_vty_conf.c b/ldpd/ldp_vty_conf.c
@@ -119,6 +119,8 @@ ldp_af_iface_config_write(struct vty *vty, int af)
 		    ia->hello_interval != 0)
 			vty_out (vty, "   discovery hello interval %u\n",
 			    ia->hello_interval);
+		if (ia->disable_establish_hello)
+			vty_out (vty, "   disable-establish-hello\n");
 
 		vty_out (vty, "  exit\n");
 	}
@@ -632,6 +634,36 @@ ldp_vty_disc_interval(struct vty *vty, const char *negate,
 	return (CMD_SUCCESS);
 }
 
+int
+ldp_vty_disable_establish_hello(struct vty *vty,
+	const char *negate)
+{
+	struct iface		*iface;
+	struct iface_af		*ia;
+	int			 af;
+
+	switch (vty->node) {
+	case LDP_IPV4_IFACE_NODE:
+	case LDP_IPV6_IFACE_NODE:
+		af = ldp_vty_get_af(vty);
+		iface = VTY_GET_CONTEXT(iface);
+		VTY_CHECK_CONTEXT(iface);
+
+		ia = iface_af_get(iface, af);
+		if (negate)
+			ia->disable_establish_hello = 0;
+		else
+			ia->disable_establish_hello = 1;
+
+		ldp_config_apply(vty, vty_conf);
+		break;
+	default:
+		fatalx("ldp_vty_disable_establish_hello: unexpected node");
+	}
+
+	return (CMD_SUCCESS);
+}
+
 int
 ldp_vty_targeted_hello_accept(struct vty *vty, const char *negate,
     const char *acl_from_str)

diff --git a/ldpd/ldpd.c b/ldpd/ldpd.c
@@ -1604,6 +1604,7 @@ merge_iface_af(struct iface_af *ia, struct iface_af *xi)
 	}
 	ia->hello_holdtime = xi->hello_holdtime;
 	ia->hello_interval = xi->hello_interval;
+	ia->disable_establish_hello = xi->disable_establish_hello;
 }
 
 static void

diff --git a/ldpd/ldpd.h b/ldpd/ldpd.h
@@ -332,6 +332,7 @@ struct iface_af {
 	struct event *hello_timer;
 	uint16_t		 hello_holdtime;
 	uint16_t		 hello_interval;
+	int disable_establish_hello;
 };
 
 struct iface_ldp_sync {

diff --git a/ldpd/neighbor.c b/ldpd/neighbor.c
@@ -630,8 +630,9 @@ nbr_establish_connection(struct nbr *nbr)
 	 * an adjacency as well.
 	 */
 	RB_FOREACH(adj, nbr_adj_head, &nbr->adj_tree)
-		send_hello(adj->source.type, adj->source.link.ia,
-		    adj->source.target);
+		if (!(adj->source.type == HELLO_LINK && adj->source.link.ia->disable_establish_hello))
+			send_hello(adj->source.type, adj->source.link.ia,
+				adj->source.target);
 
 	if (connect(nbr->fd, &remote_su.sa, sockaddr_len(&remote_su.sa)) == -1) {
 		if (errno == EINPROGRESS) {

diff --git a/tests/topotests/ldp_establish_hello_topo1/r1/ldpd.conf b/tests/topotests/ldp_establish_hello_topo1/r1/ldpd.conf
@@ -0,0 +1,21 @@
+hostname r1
+log file ldpd.log
+!
+! debug mpls ldp zebra
+! debug mpls ldp event
+! debug mpls ldp errors
+! debug mpls ldp messages recv
+! debug mpls ldp messages sent
+! debug mpls ldp discovery hello recv
+! debug mpls ldp discovery hello sent
+!
+mpls ldp
+ router-id 1.1.1.1
+ !
+ address-family ipv4
+  discovery transport-address 1.1.1.1
+  !
+ !
+!
+line vty
+!
diff --git a/tests/topotests/ldp_establish_hello_topo1/r1/zebra.conf b/tests/topotests/ldp_establish_hello_topo1/r1/zebra.conf
@@ -0,0 +1,17 @@
+log file zebra.log
+!
+hostname r1
+!
+interface lo
+ ip address 1.1.1.1/32
+!
+interface r1-eth0
+ description to sw0
+ ip address 10.0.1.1/24
+ no link-detect
+!
+ip forwarding
+!
+!
+line vty
+!
diff --git a/tests/topotests/ldp_establish_hello_topo1/r2/ldpd.conf b/tests/topotests/ldp_establish_hello_topo1/r2/ldpd.conf
@@ -0,0 +1,21 @@
+hostname r2
+log file ldpd.log
+!
+! debug mpls ldp zebra
+! debug mpls ldp event
+! debug mpls ldp errors
+! debug mpls ldp messages recv
+! debug mpls ldp messages sent
+! debug mpls ldp discovery hello recv
+! debug mpls ldp discovery hello sent
+!
+mpls ldp
+ router-id 2.2.2.2
+ !
+ address-family ipv4
+  discovery transport-address 2.2.2.2
+  !
+ !
+!
+line vty
+!
diff --git a/tests/topotests/ldp_establish_hello_topo1/r2/zebra.conf b/tests/topotests/ldp_establish_hello_topo1/r2/zebra.conf
@@ -0,0 +1,17 @@
+log file zebra.log
+!
+hostname r2
+!
+interface lo
+ ip address 2.2.2.2/32
+!
+interface r2-eth0
+ description to sw0
+ ip address 10.0.1.2/24
+ no link-detect
+!
+ip forwarding
+!
+!
+line vty
+!
diff --git a/tests/topotests/ldp_establish_hello_topo1/r3/ldpd.conf b/tests/topotests/ldp_establish_hello_topo1/r3/ldpd.conf
@@ -0,0 +1,21 @@
+hostname r3
+log file ldpd.log
+!
+! debug mpls ldp zebra
+! debug mpls ldp event
+! debug mpls ldp errors
+! debug mpls ldp messages recv
+! debug mpls ldp messages sent
+! debug mpls ldp discovery hello recv
+! debug mpls ldp discovery hello sent
+!
+mpls ldp
+ router-id 3.3.3.3
+ !
+ address-family ipv4
+  discovery transport-address 3.3.3.3
+  !
+ !
+!
+line vty
+!
diff --git a/tests/topotests/ldp_establish_hello_topo1/r3/zebra.conf b/tests/topotests/ldp_establish_hello_topo1/r3/zebra.conf
@@ -0,0 +1,17 @@
+log file zebra.log
+!
+hostname r3
+!
+interface lo
+ ip address 3.3.3.3/32
+!
+interface r3-eth0
+ description to sw0
+ ip address 10.0.1.3/24
+ no link-detect
+!
+ip forwarding
+!
+!
+line vty
+!
diff --git a/tests/topotests/ldp_establish_hello_topo1/test_establish_hello_topo1.dot b/tests/topotests/ldp_establish_hello_topo1/test_establish_hello_topo1.dot
@@ -0,0 +1,51 @@
+## Color coding:
+#########################
+##  Main FRR: #f08080  red
+##  Switches: #d0e0d0  gray
+##  RIP:      #19e3d9  Cyan
+##  RIPng:    #fcb314  dark yellow
+##  OSPFv2:   #32b835  Green
+##  OSPFv3:   #19e3d9  Cyan
+##  ISIS IPv4 #fcb314  dark yellow
+##  ISIS IPv6 #9a81ec  purple
+##  BGP IPv4  #eee3d3  beige
+##  BGP IPv6  #fdff00  yellow
+##### Colors (see http://www.color-hex.com/)
+
+graph template {
+	label="Test Topology - LDP-ESTABLISH-HELLO 1";
+
+	# Routers
+	r1 [
+		shape=doubleoctagon,
+		label="1.1.1.1",
+		fillcolor="#f08080",
+		style=filled,
+	];
+	r2 [
+		shape=doubleoctagon
+		label="2.2.2.2",
+		fillcolor="#f08080",
+		style=filled,
+	];
+	r3 [
+		shape=doubleoctagon
+		label="3.3.3.3",
+		fillcolor="#f08080",
+		style=filled,
+	];
+
+	# Switches
+	sw0 [
+		shape=oval,
+		label="10.0.1.0/24",
+		fillcolor="#d0e0d0",
+		style=filled,
+	];
+
+	# Connections
+
+	r1 -- sw0 [label="r1-eth0"];
+	r2 -- sw0 [label="r2-eth0"];
+	r3 -- sw0 [label="r3-eth0"];
+}