Merge pull request #15259 from dmytroshytyi-6WIND/nexthop_resolution

zebra: add LSP entry to nexthop via recursive (part 2)

bgpd/bgp_route.c

@@ -4634,7 +4634,22 @@ void bgp_update(struct peer *peer, const struct prefix *p, uint32_t addpath_id,
 		if (aspath_get_last_as(attr->aspath) == bgp->as)
 			do_loop_check = 0;
 
-	if (CHECK_FLAG(peer->af_flags[afi][safi], PEER_FLAG_REFLECTOR_CLIENT))
+	/* When using bgp ipv4 labeled session, the local prefix is
+	 * received by a peer, and finds out that the proposed prefix
+	 * and its next-hop are the same. To avoid a route loop locally,
+	 * no nexthop entry is referenced for that prefix, and the route
+	 * will not be selected.
+	 *
+	 * As it has been done for ipv4-unicast, apply the following fix
+	 * for labeled address families: when the received peer is
+	 * a route reflector, the prefix has to be selected, even if the
+	 * route can not be installed locally.
+	 */
+	if (CHECK_FLAG(peer->af_flags[afi][safi], PEER_FLAG_REFLECTOR_CLIENT) ||
+	    (safi == SAFI_UNICAST && !peer->afc[afi][safi] &&
+	     peer->afc[afi][SAFI_LABELED_UNICAST] &&
+	     CHECK_FLAG(peer->af_flags[afi][SAFI_LABELED_UNICAST],
+			PEER_FLAG_REFLECTOR_CLIENT)))
 		bgp_nht_param_prefix = NULL;
 	else
 		bgp_nht_param_prefix = p;

doc/user/zebra.rst

@@ -815,6 +815,16 @@ Allocated label chunks table can be dumped using the command
    range is configured, static label requests that match that
    range are not accepted.
 
+FEC nexthop entry resolution over MPLS networks
+-----------------------------------------------
+
+The LSP associated with a BGP labeled route is normally restricted to
+directly-connected nexthops. If connected nexthops are not available,
+the LSP entry will not be installed. This command permits the use of
+recursive resolution for LSPs, similar to that available for IP routes.
+
+.. clicmd:: mpls fec nexthop-resolution
+
 .. _zebra-srv6:
 
 Segment-Routing IPv6

lib/nexthop.c

@@ -713,6 +713,15 @@ struct nexthop *nexthop_next(const struct nexthop *nexthop)
 	return NULL;
 }
 
+struct nexthop *nexthop_next_resolution(const struct nexthop *nexthop,
+					bool nexthop_resolution)
+{
+	if (nexthop_resolution)
+		return nexthop_next(nexthop);
+	/* no resolution attempt */
+	return nexthop->next;
+}
+
 /* Return the next nexthop in the tree that is resolved and active */
 struct nexthop *nexthop_next_active_resolved(const struct nexthop *nexthop)
 {

lib/nexthop.h

@@ -225,6 +225,8 @@ extern bool nexthop_labels_match(const struct nexthop *nh1,
 extern const char *nexthop2str(const struct nexthop *nexthop,
 			       char *str, int size);
 extern struct nexthop *nexthop_next(const struct nexthop *nexthop);
+extern struct nexthop *nexthop_next_resolution(const struct nexthop *nexthop,
+					       bool nexthop_resolution);
 extern struct nexthop *
 nexthop_next_active_resolved(const struct nexthop *nexthop);
 extern unsigned int nexthop_level(const struct nexthop *nexthop);

tests/topotests/zebra_fec_nexthop_resolution/r1/bgpd.conf

@@ -0,0 +1,24 @@
+!
+router bgp 65500
+ bgp router-id 192.0.2.1
+ neighbor 192.0.2.3 remote-as 65500
+ neighbor 192.0.2.3 update-source lo
+ neighbor 192.0.2.7 remote-as 65500
+ neighbor 192.0.2.7 ttl-security hops 10
+ neighbor 192.0.2.7 disable-connected-check
+ neighbor 192.0.2.7 update-source lo
+ !
+ address-family ipv4 unicast
+  network 192.0.2.1/32
+  no neighbor 192.0.2.3 activate
+  neighbor 192.0.2.7 activate
+ exit-address-family
+ !
+ address-family ipv4 labeled-unicast
+  neighbor 192.0.2.3 activate
+  neighbor 192.0.2.3 route-reflector-client
+  neighbor 192.0.2.3 next-hop-self force
+ exit-address-family
+ !
+exit
+!

tests/topotests/zebra_fec_nexthop_resolution/r1/ospfd.conf.after

@@ -0,0 +1,25 @@
+log stdout
+!
+interface lo
+ ip ospf passive
+exit
+!
+interface r1-eth0
+ ip ospf network point-to-point
+ ip ospf hello-interval 1
+exit
+!
+router ospf
+ ospf router-id 192.0.2.1
+ network 192.0.2.1/32 area 0.0.0.0
+ network 192.168.1.0/24 area 0.0.0.0
+ passive-interface lo
+ capability opaque
+ mpls-te on
+ mpls-te router-address 192.0.2.1
+ segment-routing on
+ segment-routing global-block 1000 10000 local-block 32000 32999
+ segment-routing node-msd 8
+ segment-routing prefix 192.0.2.1/32 index 11
+exit
+!

tests/topotests/zebra_fec_nexthop_resolution/r1/zebra.conf

@@ -0,0 +1,13 @@
+interface lo
+ ip address 192.0.2.1/32
+ mpls enable
+exit
+!
+interface r1-eth0
+ ip address 192.168.1.1/24
+ mpls enable
+ link-params
+  enable
+  exit-link-params
+exit
+!

tests/topotests/zebra_fec_nexthop_resolution/r2/bgpd.conf

@@ -0,0 +1,23 @@
+router bgp 65500
+ bgp router-id 192.0.2.2
+ neighbor 192.0.2.1 remote-as 65500
+ neighbor 192.0.2.1 update-source lo
+ neighbor 192.0.2.3 remote-as 65500
+ neighbor 192.0.2.3 update-source lo
+ !
+ address-family ipv4 unicast
+  network 192.0.2.2/32
+  no neighbor 192.0.2.1 activate
+  no neighbor 192.0.2.3 activate
+ exit-address-family
+ !
+ address-family ipv4 labeled-unicast
+  neighbor 192.0.2.1 activate
+  neighbor 192.0.2.1 route-reflector-client
+  neighbor 192.0.2.1 next-hop-self force
+  neighbor 192.0.2.3 activate
+  neighbor 192.0.2.3 route-reflector-client
+  neighbor 192.0.2.3 next-hop-self force
+ exit-address-family
+exit
+!

tests/topotests/zebra_fec_nexthop_resolution/r2/isisd.conf

@@ -0,0 +1,25 @@
+!
+interface lo
+ ip router isis 1
+ isis hello-interval 1
+ isis hello-multiplier 3
+exit
+!
+interface r2-eth1
+ ip router isis 2
+ isis hello-interval 1
+ isis hello-multiplier 3
+exit
+!
+router isis 1
+ is-type level-1
+ net 49.0000.0007.e901.2223.00
+ lsp-timers gen-interval 1 refresh-interval 900 max-lifetime 1200
+ mpls-te on
+ mpls-te router-address 192.0.2.2
+ segment-routing on
+ segment-routing global-block 11000 20000 local-block 36000 36999
+ segment-routing node-msd 8
+ segment-routing prefix 192.0.2.2/32 index 22 no-php-flag
+exit
+!

tests/topotests/zebra_fec_nexthop_resolution/r2/ospfd.conf.after

@@ -0,0 +1,32 @@
+log stdout
+!
+interface lo
+ ip ospf network point-to-point
+ ip ospf passive
+exit
+!
+interface r2-eth0
+ ip ospf network point-to-point
+ ip ospf hello-interval 1
+exit
+!
+interface r2-eth1
+ ip ospf network point-to-point
+ ip ospf hello-interval 1
+exit
+!
+router ospf
+ ospf router-id 192.0.2.2
+ network 192.0.2.2/32 area 0.0.0.0
+ network 192.168.1.0/24 area 0.0.0.0
+ network 192.168.2.0/24 area 0.0.0.0
+ passive-interface lo
+ capability opaque
+ mpls-te on
+ mpls-te router-address 192.0.2.2
+ segment-routing on
+ segment-routing global-block 1000 10000 local-block 36000 36999
+ segment-routing node-msd 8
+ segment-routing prefix 192.0.2.2/32 index 22
+exit
+!

tests/topotests/zebra_fec_nexthop_resolution/r2/zebra.conf

@@ -0,0 +1,16 @@
+!
+interface lo
+ ip address 192.0.2.2/32
+ mpls enable
+exit
+!
+interface r2-eth0
+ ip address 192.168.1.2/24
+ mpls enable
+exit
+!
+interface r2-eth1
+ ip address 192.168.2.2/24
+ mpls enable
+exit
+!

tests/topotests/zebra_fec_nexthop_resolution/r3/bgpd.conf

@@ -0,0 +1,23 @@
+router bgp 65500
+ bgp router-id 192.0.2.3
+ neighbor 192.0.2.1 remote-as 65500
+ neighbor 192.0.2.1 update-source lo
+ neighbor 192.0.2.5 remote-as 65500
+ neighbor 192.0.2.5 update-source lo
+ !
+ address-family ipv4 unicast
+  network 192.0.2.3/32
+  no neighbor 192.0.2.1 activate
+  no neighbor 192.0.2.5 activate
+ exit-address-family
+ !
+ address-family ipv4 labeled-unicast
+  neighbor 192.0.2.1 activate
+  neighbor 192.0.2.1 route-reflector-client
+  neighbor 192.0.2.1 next-hop-self force
+  neighbor 192.0.2.5 activate
+  neighbor 192.0.2.5 route-reflector-client
+  neighbor 192.0.2.5 next-hop-self force
+ exit-address-family
+exit
+!

tests/topotests/zebra_fec_nexthop_resolution/r3/isisd.conf

@@ -0,0 +1,25 @@
+!
+interface lo
+ ip router isis 1
+ isis hello-interval 1
+ isis hello-multiplier 3
+exit
+!
+interface r3-eth1
+ ip router isis 1
+ isis hello-interval 1
+ isis hello-multiplier 3
+exit
+!
+router isis 1
+ is-type level-1
+ net 49.0000.0007.e901.3333.00
+ lsp-timers gen-interval 1 refresh-interval 900 max-lifetime 1200
+ mpls-te on
+ mpls-te router-address 192.0.2.3
+ segment-routing on
+ segment-routing global-block 11000 12000 local-block 36000 36999
+ segment-routing node-msd 8
+ segment-routing prefix 192.0.2.3/32 index 33
+exit
+!

tests/topotests/zebra_fec_nexthop_resolution/r3/ospfd.conf.after

@@ -0,0 +1,26 @@
+log stdout
+!
+interface lo
+ ip ospf network point-to-point
+ ip ospf passive
+exit
+!
+interface r3-eth0
+ ip ospf network point-to-point
+ ip ospf hello-interval 1
+exit
+!
+router ospf
+ ospf router-id 192.0.2.3
+ network 192.0.2.3/32 area 0.0.0.0
+ network 192.168.2.0/24 area 0.0.0.0
+ passive-interface lo
+ capability opaque
+ mpls-te on
+ mpls-te router-address 192.0.2.3
+ segment-routing on
+ segment-routing global-block 1000 10000 local-block 30000 30999
+ segment-routing node-msd 8
+ segment-routing prefix 192.0.2.3/32 index 33
+exit
+!

tests/topotests/zebra_fec_nexthop_resolution/r3/zebra.conf

@@ -0,0 +1,19 @@
+!
+interface lo
+ ip address 192.0.2.3/32
+ mpls enable
+exit
+!
+interface r3-eth0
+ ip address 192.168.2.3/24
+ mpls enable
+ link-params
+  enable
+  exit-link-params
+exit
+!
+interface r3-eth1
+ ip address 192.168.3.3/24
+ mpls enable
+exit
+!

tests/topotests/zebra_fec_nexthop_resolution/r4/bgpd.conf

@@ -0,0 +1,24 @@
+!
+router bgp 65500
+ bgp router-id 192.0.2.4
+ neighbor 192.0.2.1 remote-as 65500
+ neighbor 192.0.2.1 ttl-security hops 10
+ neighbor 192.0.2.1 disable-connected-check
+ neighbor 192.0.2.1 update-source lo
+ neighbor 192.0.2.3 remote-as 65500
+ neighbor 192.0.2.3 update-source lo
+ !
+ address-family ipv4 unicast
+  network 192.0.2.4/32
+  neighbor 192.0.2.1 activate
+  no neighbor 192.0.2.3 activate
+ exit-address-family
+ !
+ address-family ipv4 labeled-unicast
+  neighbor 192.0.2.3 activate
+  neighbor 192.0.2.3 route-reflector-client
+  neighbor 192.0.2.3 next-hop-self force
+ exit-address-family
+ !
+exit
+!

tests/topotests/zebra_fec_nexthop_resolution/r4/isisd.conf

@@ -0,0 +1,31 @@
+!
+interface lo
+ ip router isis 1
+ isis hello-interval 1
+ isis hello-multiplier 3
+exit
+!
+interface r4-eth0
+ ip router isis 1
+ isis hello-interval 1
+ isis hello-multiplier 3
+exit
+!
+interface r4-eth1
+ ip router isis 1
+ isis hello-interval 1
+ isis hello-multiplier 3
+exit
+!
+router isis 1
+ is-type level-1
+ net 49.0000.0007.e901.4444.00
+ lsp-timers gen-interval 1 refresh-interval 900 max-lifetime 1200
+ mpls-te on
+ mpls-te router-address 192.0.2.4
+ segment-routing on
+ segment-routing global-block 11000 12000 local-block 37000 37999
+ segment-routing node-msd 8
+ segment-routing prefix 192.0.2.4/32 index 44
+exit
+!

tests/topotests/zebra_fec_nexthop_resolution/r4/ospfd.conf

@@ -0,0 +1,19 @@
+!
+interface lo
+ ip ospf area 0
+ ip ospf passive
+exit
+!
+interface r4-eth0
+ ip ospf area 0
+exit
+!
+router ospf
+ mpls-te on
+ mpls-te router-address 192.0.2.4
+ segment-routing on
+ segment-routing global-block 21000 29000 local-block 31000 31999
+ segment-routing node-msd 8
+ segment-routing prefix 192.0.2.4/32 index 44 no-php-flag
+exit
+!

tests/topotests/zebra_fec_nexthop_resolution/r4/zebra.conf

@@ -0,0 +1,16 @@
+!
+interface lo
+ ip address 192.0.2.4/32
+ mpls enable
+exit
+!
+interface r4-eth0
+ ip address 192.168.3.4/24
+ mpls enable
+exit
+!
+interface r4-eth1
+ ip address 192.168.4.4/24
+ mpls enable
+exit
+!

tests/topotests/zebra_fec_nexthop_resolution/r5/bgpd.conf

@@ -0,0 +1,23 @@
+router bgp 65500
+ bgp router-id 192.0.2.5
+ neighbor 192.0.2.3 remote-as 65500
+ neighbor 192.0.2.3 update-source lo
+ neighbor 192.0.2.7 remote-as 65500
+ neighbor 192.0.2.7 update-source lo
+ !
+ address-family ipv4 unicast
+  network 192.0.2.5/32
+  no neighbor 192.0.2.3 activate
+  no neighbor 192.0.2.7 activate
+ exit-address-family
+ !
+ address-family ipv4 labeled-unicast
+  neighbor 192.0.2.3 activate
+  neighbor 192.0.2.3 route-reflector-client
+  neighbor 192.0.2.3 next-hop-self force
+  neighbor 192.0.2.7 activate
+  neighbor 192.0.2.7 route-reflector-client
+  neighbor 192.0.2.7 next-hop-self force
+ exit-address-family
+exit
+!

tests/topotests/zebra_fec_nexthop_resolution/r5/isisd.conf

@@ -0,0 +1,26 @@
+!
+interface lo
+ ip router isis 1
+ isis hello-interval 1
+ isis hello-multiplier 3
+ isis passive
+exit
+!
+interface r5-eth0
+ ip router isis 1
+ isis hello-interval 1
+ isis hello-multiplier 3
+exit
+!
+router isis 1
+ is-type level-1
+ net 49.0000.0007.e901.5555.00
+ lsp-timers gen-interval 1 refresh-interval 900 max-lifetime 1200
+ mpls-te on
+ mpls-te router-address 192.0.2.5
+ segment-routing on
+ segment-routing global-block 11000 12000 local-block 33000 33999
+ segment-routing node-msd 8
+ segment-routing prefix 192.0.2.5/32 index 55
+exit
+!

tests/topotests/zebra_fec_nexthop_resolution/r5/ospfd.conf.after

@@ -0,0 +1,26 @@
+log stdout
+!
+interface lo
+ ip ospf network point-to-point
+ ip ospf passive
+exit
+!
+interface r5-eth1
+ ip ospf network point-to-point
+ ip ospf hello-interval 1
+exit
+!
+router ospf
+ ospf router-id 192.0.2.5
+ network 192.0.2.5/32 area 0.0.0.0
+ network 192.168.5.0/24 area 0.0.0.0
+ passive-interface lo
+ capability opaque
+ mpls-te on
+ mpls-te router-address 192.0.2.5
+ segment-routing on
+ segment-routing global-block 21000 22000 local-block 35000 35999
+ segment-routing node-msd 8
+ segment-routing prefix 192.0.2.5/32 index 55
+exit
+!

tests/topotests/zebra_fec_nexthop_resolution/r5/zebra.conf

@@ -0,0 +1,19 @@
+!
+interface lo
+ ip address 192.0.2.5/32
+ mpls enable
+exit
+!
+interface r5-eth0
+ ip address 192.168.4.5/24
+ mpls enable
+exit
+!
+interface r5-eth1
+ ip address 192.168.5.5/24
+ mpls enable
+ link-params
+  enable
+  exit-link-params
+exit
+!

tests/topotests/zebra_fec_nexthop_resolution/r6/ospfd.conf.after

@@ -0,0 +1,32 @@
+log stdout
+!
+interface lo
+ ip ospf network point-to-point
+ ip ospf passive
+exit
+!
+interface r6-eth0
+ ip ospf network point-to-point
+ ip ospf hello-interval 1
+exit
+!
+interface r6-eth1
+ ip ospf network point-to-point
+ ip ospf hello-interval 1
+exit
+!
+router ospf
+ ospf router-id 192.0.2.6
+ segment-routing on
+ segment-routing global-block 21000 22000 local-block 38000 38999
+ network 192.0.2.6/32 area 0.0.0.0
+ network 192.168.5.0/24 area 0.0.0.0
+ network 192.168.6.0/24 area 0.0.0.0
+ passive-interface lo
+ capability opaque
+ mpls-te on
+ mpls-te router-address 192.0.2.6
+ segment-routing node-msd 8
+ segment-routing prefix 192.0.2.6/32 index 66
+exit
+!

tests/topotests/zebra_fec_nexthop_resolution/r6/zebra.conf

@@ -0,0 +1,22 @@
+!
+interface lo
+ ip address 192.0.2.6/32
+ mpls enable
+exit
+!
+interface r6-eth0
+ ip address 192.168.5.6/24
+ mpls enable
+ link-params
+  enable
+  exit-link-params
+exit
+!
+interface r6-eth1
+ ip address 192.168.6.6/24
+ mpls enable
+ link-params
+  enable
+  exit-link-params
+exit
+!

tests/topotests/zebra_fec_nexthop_resolution/r7/bgpd.conf

@@ -0,0 +1,24 @@
+!
+router bgp 65500
+ bgp router-id 192.0.2.7
+ neighbor 192.0.2.1 remote-as 65500
+ neighbor 192.0.2.1 ttl-security hops 10
+ neighbor 192.0.2.1 disable-connected-check
+ neighbor 192.0.2.1 update-source lo
+ neighbor 192.0.2.5 remote-as 65500
+ neighbor 192.0.2.5 update-source lo
+ !
+ address-family ipv4 unicast
+  network 192.0.2.7/32
+  neighbor 192.0.2.1 activate
+  no neighbor 192.0.2.5 activate
+ exit-address-family
+ !
+ address-family ipv4 labeled-unicast
+  neighbor 192.0.2.5 activate
+  neighbor 192.0.2.5 route-reflector-client
+  neighbor 192.0.2.5 next-hop-self force
+ exit-address-family
+ !
+exit
+!

tests/topotests/zebra_fec_nexthop_resolution/r7/ospfd.conf.after

@@ -0,0 +1,26 @@
+log stdout
+!
+interface lo
+ ip ospf network point-to-point
+ ip ospf passive
+exit
+!
+interface r7-eth0
+ ip ospf network point-to-point
+ ip ospf hello-interval 1
+exit
+!
+router ospf
+ ospf router-id 192.0.2.7
+ network 192.0.2.7/32 area 0.0.0.0
+ network 192.168.6.0/24 area 0.0.0.0
+ passive-interface lo
+ capability opaque
+ mpls-te on
+ mpls-te router-address 192.0.2.7
+ segment-routing on
+ segment-routing global-block 21000 22000 local-block 31000 31999
+ segment-routing node-msd 8
+ segment-routing prefix 192.0.2.7/32 index 77
+exit
+!

tests/topotests/zebra_fec_nexthop_resolution/r7/zebra.conf

@@ -0,0 +1,14 @@
+!
+interface lo
+ ip address 192.0.2.7/32
+ mpls enable
+exit
+!
+interface r7-eth0
+ ip address 192.168.6.7/24
+ mpls enable
+ link-params
+  enable
+  exit-link-params
+exit
+!

tests/topotests/zebra_fec_nexthop_resolution/test_zebra_fec_nexthop_resolution.py

@@ -0,0 +1,259 @@
+#!/usr/bin/env python
+
+#
+# Copyright 2022 6WIND S.A.
+#
+# Permission to use, copy, modify, and/or distribute this software
+# for any purpose with or without fee is hereby granted, provided
+# that the above copyright notice and this permission notice appear
+# in all copies.
+#
+# THE SOFTWARE IS PROVIDED "AS IS" AND NETDEF DISCLAIMS ALL WARRANTIES
+# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NETDEF BE LIABLE FOR
+# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY
+# DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
+# WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
+# ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+# OF THIS SOFTWARE.
+#
+
+"""
+Check if fec nexthop resolution works correctly.
+"""
+
+import os
+import sys
+import json
+import pytest
+import functools
+
+CWD = os.path.dirname(os.path.realpath(__file__))
+sys.path.append(os.path.join(CWD, "../"))
+
+# pylint: disable=C0413
+from lib import topotest
+from lib.topogen import Topogen, TopoRouter, get_topogen
+from lib.common_config import step
+
+pytestmark = [pytest.mark.bgpd]
+
+
+def build_topo(tgen):
+    """
+    r1 ---- r2 ---- r3 ---- r4 ----- r5 ---- r6 ---- r7
+     <--- ospf ----> <---- isis -----> <--- ospf ---->
+    """
+    for routern in range(1, 8):
+        tgen.add_router("r{}".format(routern))
+
+    switch1 = tgen.add_switch("s1")
+    switch1.add_link(tgen.gears["r1"])
+    switch1.add_link(tgen.gears["r2"])
+
+    switch2 = tgen.add_switch("s2")
+    switch2.add_link(tgen.gears["r2"])
+    switch2.add_link(tgen.gears["r3"])
+
+    switch3 = tgen.add_switch("s3")
+    switch3.add_link(tgen.gears["r3"])
+    switch3.add_link(tgen.gears["r4"])
+
+    switch4 = tgen.add_switch("s4")
+    switch4.add_link(tgen.gears["r4"])
+    switch4.add_link(tgen.gears["r5"])
+
+    switch5 = tgen.add_switch("s5")
+    switch5.add_link(tgen.gears["r5"])
+    switch5.add_link(tgen.gears["r6"])
+
+    switch6 = tgen.add_switch("s6")
+    switch6.add_link(tgen.gears["r6"])
+    switch6.add_link(tgen.gears["r7"])
+
+
+def setup_module(mod):
+    tgen = Topogen(build_topo, mod.__name__)
+    tgen.start_topology()
+
+    router_list = tgen.routers()
+
+    def _enable_mpls_misc(router):
+        router.run("modprobe mpls_router")
+        router.run("echo 100000 > /proc/sys/net/mpls/platform_labels")
+        router.run("echo 1 > /proc/sys/net/mpls/conf/lo/input")
+
+    router = tgen.gears["r1"]
+    _enable_mpls_misc(router)
+
+    router = tgen.gears["r2"]
+    _enable_mpls_misc(router)
+
+    router = tgen.gears["r3"]
+    _enable_mpls_misc(router)
+
+    router = tgen.gears["r4"]
+    _enable_mpls_misc(router)
+
+    router = tgen.gears["r5"]
+    _enable_mpls_misc(router)
+
+    router = tgen.gears["r6"]
+    _enable_mpls_misc(router)
+
+    router = tgen.gears["r7"]
+    _enable_mpls_misc(router)
+
+    for i, (rname, router) in enumerate(router_list.items(), 1):
+        router.load_config(
+            TopoRouter.RD_ZEBRA, os.path.join(CWD, "{}/zebra.conf".format(rname))
+        )
+        if rname in ("r1", "r3", "r5", "r7"):
+            router.load_config(
+                TopoRouter.RD_BGP, os.path.join(CWD, "{}/bgpd.conf".format(rname))
+            )
+        if rname in ("r3", "r4", "r5"):
+            router.load_config(
+                TopoRouter.RD_ISIS, os.path.join(CWD, "{}/isisd.conf".format(rname))
+            )
+        if rname in ("r1", "r2", "r3", "r5", "r6", "r7"):
+            router.load_config(
+                TopoRouter.RD_OSPF, os.path.join(CWD, "{}/ospfd.conf".format(rname))
+            )
+
+    tgen.start_router()
+
+
+def teardown_module(mod):
+    tgen = get_topogen()
+    tgen.stop_topology()
+
+
+# There are some startup issued when initialising OSPF
+# To avoid those issues, load the ospf configuration after zebra started
+def test_zebra_fec_nexthop_resolution_finalise_ospf_config():
+    tgen = get_topogen()
+
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+
+    topotest.sleep(2)
+
+    tgen.net["r1"].cmd("vtysh -f {}/r1/ospfd.conf.after".format(CWD))
+    tgen.net["r2"].cmd("vtysh -f {}/r2/ospfd.conf.after".format(CWD))
+    tgen.net["r3"].cmd("vtysh -f {}/r3/ospfd.conf.after".format(CWD))
+    tgen.net["r5"].cmd("vtysh -f {}/r5/ospfd.conf.after".format(CWD))
+    tgen.net["r6"].cmd("vtysh -f {}/r6/ospfd.conf.after".format(CWD))
+    tgen.net["r7"].cmd("vtysh -f {}/r7/ospfd.conf.after".format(CWD))
+
+
+def test_zebra_fec_nexthop_resolution_bgp():
+    tgen = get_topogen()
+
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+
+    def _check_bgp_session():
+        r1 = tgen.gears["r1"]
+
+        tgen.gears["r3"].vtysh_cmd("config \n no mpls fec nexthop-resolution \n end")
+        tgen.gears["r3"].vtysh_cmd("config \n mpls fec nexthop-resolution \n end")
+        tgen.gears["r5"].vtysh_cmd("config \n no mpls fec nexthop-resolution \n end")
+        tgen.gears["r5"].vtysh_cmd("config \n mpls fec nexthop-resolution \n end")
+        output = json.loads(r1.vtysh_cmd("show bgp summary json"))
+
+        if output["ipv4Unicast"]["peers"]["192.0.2.7"]["state"] == "Established":
+            return None
+        return False
+
+    test_func1 = functools.partial(_check_bgp_session)
+    _, result1 = topotest.run_and_expect(test_func1, None, count=60, wait=0.5)
+    assert result1 is None, "Failed to verify the fec_nexthop_resolution: bgp session"
+
+
+def test_zebra_fec_nexthop_resolution_ping():
+    tgen = get_topogen()
+
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+
+    def _check_ping_launch():
+        r1 = tgen.gears["r1"]
+
+        ping_launch = "ping 192.0.2.7 -I 192.0.2.1 -c 1"
+        selected_lines = r1.run(ping_launch).splitlines()[-2:-1]
+        rtx_stats = "".join(selected_lines[0].split(",")[0:3])
+        current = topotest.normalize_text(rtx_stats)
+
+        expected_stats = "1 packets transmitted 1 received 0% packet loss"
+        expected = topotest.normalize_text(expected_stats)
+
+        if current == expected:
+            return None
+
+        return False
+
+    test_func2 = functools.partial(_check_ping_launch)
+    _, result2 = topotest.run_and_expect(test_func2, None, count=60, wait=1)
+    assert result2 is None, "Failed to verify the fec_nexthop_resolution: ping"
+
+
+def test_zebra_fec_nexthop_resolution_table():
+    tgen = get_topogen()
+
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+
+    def _zebra_check_mpls_table():
+        r3 = tgen.gears["r3"]
+        inLabel = 0
+        outLabels = 0
+
+        """
+        Retrieve inLabel from MPLS FEC table
+        """
+        mpls_fec = r3.vtysh_cmd("show mpls fec 192.0.2.7/32")
+        lines = mpls_fec.split("\n")
+        for line in lines:
+            if "Label" in line:
+                inLabel = line.split(": ", 1)[1]
+
+        """
+        Retrieve outLabel from BGP
+        """
+        output = json.loads(r3.vtysh_cmd("show ip route 192.0.2.7/32 json"))
+
+        outLabels = output["192.0.2.7/32"][0]["nexthops"][1]["labels"]
+
+        if (inLabel == 0) or (outLabels == 0):
+            return True
+
+        """
+        Compare expected data with real data
+        """
+        output = json.loads(r3.vtysh_cmd("show mpls table " + str(inLabel) + " json"))
+
+        expected = {
+            "inLabel": int(inLabel),
+            "installed": True,
+            "nexthops": [
+                {
+                    "type": "BGP",
+                    "outLabel": outLabels[0],
+                    "outLabelStack": outLabels,
+                    "distance": 20,
+                    "installed": True,
+                    "nexthop": "192.168.3.4",
+                }
+            ],
+        }
+        return topotest.json_cmp(output, expected)
+
+    test_func3 = functools.partial(_zebra_check_mpls_table)
+    _, result3 = topotest.run_and_expect(test_func3, None, count=60, wait=0.5)
+    assert result3 is None, "Failed to verify the fec_nexthop_resolution: mpls table"
+
+
+if __name__ == "__main__":
+    args = ["-s"] + sys.argv[1:]
+    sys.exit(pytest.main(args))

yang/frr-zebra.yang

@@ -2856,6 +2856,16 @@ module frr-zebra {
         }
       }
 
+      container mpls {
+        description
+          "MPLS Configuration.";
+          leaf fec-nexthop-resolution {
+            type boolean;
+            description
+              "Authorise nexthop resolution over all labeled routes.";
+          }
+      }
+
       uses ribs;
 
       uses vrf-vni-mapping;

zebra/rib.h

@@ -108,8 +108,8 @@ struct route_entry {
 	uint32_t nexthop_mtu;
 
 	/* Flags of this route.
-	 * This flag's definition is in lib/zebra.h ZEBRA_FLAG_* and is exposed
+	 * This flag's definition is in lib/zclient.h ZEBRA_FLAG_* and is
-	 * to clients via Zserv
+	 * exposed to clients via Zserv
 	 */
 	uint32_t flags;
 

zebra/zebra_cli.c

@@ -2221,6 +2221,37 @@ static void lib_vrf_zebra_ipv6_resolve_via_default_cli_write(
 	}
 }
 
+DEFPY_YANG (mpls_fec_nexthop_resolution, mpls_fec_nexthop_resolution_cmd,
+      "[no$no] mpls fec nexthop-resolution",
+      NO_STR
+      MPLS_STR
+      "MPLS FEC table\n"
+      "Authorise nexthop resolution over all labeled routes.\n")
+{
+	nb_cli_enqueue_change(vty,
+			      "./frr-zebra:zebra/mpls/fec-nexthop-resolution",
+			      NB_OP_MODIFY, no ? "false" : "true");
+
+	if (vty->node == CONFIG_NODE)
+		return nb_cli_apply_changes(vty, "/frr-vrf:lib/vrf[name='%s']",
+					    VRF_DEFAULT_NAME);
+
+	return nb_cli_apply_changes(vty, NULL);
+}
+
+static void lib_vrf_mpls_fec_nexthop_resolution_cli_write(
+	struct vty *vty, const struct lyd_node *dnode, bool show_defaults)
+{
+	bool fec_nexthop_resolution = yang_dnode_get_bool(dnode, NULL);
+
+	if (fec_nexthop_resolution || show_defaults) {
+		zebra_vrf_indent_cli_write(vty, dnode);
+
+		vty_out(vty, "%smpls fec nexthop-resolution\n",
+			fec_nexthop_resolution ? "" : "no ");
+	}
+}
+
 DEFPY_YANG (vrf_netns,
        vrf_netns_cmd,
        "[no] netns ![NAME$netns_name]",
@@ -2851,6 +2882,10 @@ const struct frr_yang_module_info frr_zebra_cli_info = {
 			.xpath = "/frr-vrf:lib/vrf/frr-zebra:zebra/netns/table-range",
 			.cbs.cli_show = lib_vrf_zebra_netns_table_range_cli_write,
 		},
+		{
+			.xpath = "/frr-vrf:lib/vrf/frr-zebra:zebra/mpls/fec-nexthop-resolution",
+			.cbs.cli_show = lib_vrf_mpls_fec_nexthop_resolution_cli_write,
+		},
 		{
 			.xpath = "/frr-vrf:lib/vrf/frr-zebra:zebra/l3vni-id",
 			.cbs.cli_show = lib_vrf_zebra_l3vni_id_cli_write,
@@ -2957,6 +2992,9 @@ void zebra_cli_init(void)
 	install_element(VRF_NODE, &ip_nht_default_route_cmd);
 	install_element(VRF_NODE, &ipv6_nht_default_route_cmd);
 
+	install_element(CONFIG_NODE, &mpls_fec_nexthop_resolution_cmd);
+	install_element(VRF_NODE, &mpls_fec_nexthop_resolution_cmd);
+
 	install_element(CONFIG_NODE, &vni_mapping_cmd);
 	install_element(VRF_NODE, &vni_mapping_cmd);
 

zebra/zebra_mpls.c

@@ -37,6 +37,7 @@
 DEFINE_MTYPE_STATIC(ZEBRA, LSP, "MPLS LSP object");
 DEFINE_MTYPE_STATIC(ZEBRA, FEC, "MPLS FEC object");
 DEFINE_MTYPE_STATIC(ZEBRA, NHLFE, "MPLS nexthop object");
+DEFINE_MTYPE_STATIC(ZEBRA, NH_LABEL, "Nexthop label");
 
 bool mpls_enabled;
 bool mpls_pw_reach_strict; /* Strict reachability checking */
@@ -50,7 +51,7 @@ static int lsp_install(struct zebra_vrf *zvrf, mpls_label_t label,
 		       struct route_node *rn, struct route_entry *re);
 static int lsp_uninstall(struct zebra_vrf *zvrf, mpls_label_t label);
 static int fec_change_update_lsp(struct zebra_vrf *zvrf, struct zebra_fec *fec,
-				 mpls_label_t old_label);
+				 mpls_label_t old_label, bool uninstall);
 static int fec_send(struct zebra_fec *fec, struct zserv *client);
 static void fec_update_clients(struct zebra_fec *fec);
 static void fec_print(struct zebra_fec *fec, struct vty *vty);
@@ -161,12 +162,14 @@ static int lsp_install(struct zebra_vrf *zvrf, mpls_label_t label,
 	enum lsp_types_t lsp_type;
 	char buf[BUFSIZ];
 	int added, changed;
+	bool zvrf_nexthop_resolution;
 
 	/* Lookup table. */
 	lsp_table = zvrf->lsp_table;
 	if (!lsp_table)
 		return -1;
 
+	zvrf_nexthop_resolution = zvrf->zebra_mpls_fec_nexthop_resolution;
 	lsp_type = lsp_type_from_re_type(re->type);
 	added = changed = 0;
 
@@ -180,13 +183,20 @@ static int lsp_install(struct zebra_vrf *zvrf, mpls_label_t label,
 	 * the label advertised by the recursive nexthop (plus we don't have the
 	 * logic yet to push multiple labels).
 	 */
-	for (nexthop = re->nhe->nhg.nexthop;
+	nexthop = re->nhe->nhg.nexthop;
-	     nexthop; nexthop = nexthop->next) {
+	while (nexthop) {
-		/* Skip inactive and recursive entries. */
+		if (!CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_ACTIVE)) {
-		if (!CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_ACTIVE))
+			nexthop =
+				nexthop_next_resolution(nexthop,
+							zvrf_nexthop_resolution);
 			continue;
-		if (CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_RECURSIVE))
+		}
+		if (CHECK_FLAG(nexthop->flags, NEXTHOP_FLAG_RECURSIVE)) {
+			nexthop =
+				nexthop_next_resolution(nexthop,
+							zvrf_nexthop_resolution);
 			continue;
+		}
 
 		nhlfe = nhlfe_find(&lsp->nhlfe_list, lsp_type,
 				   nexthop->type, &nexthop->gate,
@@ -194,9 +204,13 @@ static int lsp_install(struct zebra_vrf *zvrf, mpls_label_t label,
 		if (nhlfe) {
 			/* Clear deleted flag (in case it was set) */
 			UNSET_FLAG(nhlfe->flags, NHLFE_FLAG_DELETED);
-			if (nexthop_labels_match(nhlfe->nexthop, nexthop))
+			if (nexthop_labels_match(nhlfe->nexthop, nexthop)) {
 				/* No change */
+				nexthop =
+					nexthop_next_resolution(nexthop,
+								zvrf_nexthop_resolution);
 				continue;
+			}
 
 
 			if (IS_ZEBRA_DEBUG_MPLS) {
@@ -221,11 +235,18 @@ static int lsp_install(struct zebra_vrf *zvrf, mpls_label_t label,
 				return -1;
 
 			if (IS_ZEBRA_DEBUG_MPLS) {
+				char label_str[MPLS_LABEL_STRLEN];
+
 				nhlfe2str(nhlfe, buf, BUFSIZ);
-				zlog_debug(
+				zlog_debug("Add LSP in-label %u type %d nexthop %s out-label %s",
-					"Add LSP in-label %u type %d nexthop %s out-label %u",
+					   lsp->ile.in_label, lsp_type, buf,
-					lsp->ile.in_label, lsp_type, buf,
+					   mpls_label2str(nexthop->nh_label
-					nexthop->nh_label->label[0]);
+								  ->num_labels,
+							  nexthop->nh_label->label,
+							  label_str,
+							  sizeof(label_str),
+							  nexthop->nh_label_type,
+							  0));
 			}
 
 			lsp->addr_family = NHLFE_FAMILY(nhlfe);
@@ -234,6 +255,8 @@ static int lsp_install(struct zebra_vrf *zvrf, mpls_label_t label,
 			SET_FLAG(nhlfe->flags, NHLFE_FLAG_CHANGED);
 			added++;
 		}
+		nexthop = nexthop_next_resolution(nexthop,
+						  zvrf_nexthop_resolution);
 	}
 
 	/* Queue LSP for processing if necessary. If no NHLFE got added (special
@@ -245,6 +268,8 @@ static int lsp_install(struct zebra_vrf *zvrf, mpls_label_t label,
 			return -1;
 	} else {
 		lsp_check_free(lsp_table, &lsp);
+		/* failed to install a new LSP */
+		return -1;
 	}
 
 	return 0;
@@ -353,7 +378,7 @@ static void fec_evaluate(struct zebra_vrf *zvrf)
 			fec_update_clients(fec);
 
 			/* Update label forwarding entries appropriately */
-			fec_change_update_lsp(zvrf, fec, old_label);
+			fec_change_update_lsp(zvrf, fec, old_label, false);
 		}
 	}
 }
@@ -384,7 +409,7 @@ static uint32_t fec_derive_label_from_index(struct zebra_vrf *zvrf,
  * entries, as appropriate.
  */
 static int fec_change_update_lsp(struct zebra_vrf *zvrf, struct zebra_fec *fec,
-				 mpls_label_t old_label)
+				 mpls_label_t old_label, bool uninstall)
 {
 	struct route_table *table;
 	struct route_node *rn;
@@ -416,11 +441,17 @@ static int fec_change_update_lsp(struct zebra_vrf *zvrf, struct zebra_fec *fec,
 			break;
 	}
 
-	if (!re || !zebra_rib_labeled_unicast(re))
+	if (!re || !zebra_rib_labeled_unicast(re)) {
+		if (uninstall)
+			lsp_uninstall(zvrf, fec->label);
 		return 0;
+	}
 
-	if (lsp_install(zvrf, fec->label, rn, re))
+	if (lsp_install(zvrf, fec->label, rn, re)) {
+		if (uninstall)
+			lsp_uninstall(zvrf, fec->label);
 		return -1;
+	}
 
 	return 0;
 }
@@ -447,6 +478,30 @@ static int fec_send(struct zebra_fec *fec, struct zserv *client)
 	return zserv_send_message(client, s);
 }
 
+/*
+ * Upon reconfiguring nexthop-resolution updates, update the
+ * lsp entries accordingly.
+ */
+void zebra_mpls_fec_nexthop_resolution_update(struct zebra_vrf *zvrf)
+{
+	int af;
+	struct route_node *rn;
+	struct zebra_fec *fec;
+
+	for (af = AFI_IP; af < AFI_MAX; af++) {
+		if (zvrf->fec_table[af] == NULL)
+			continue;
+		for (rn = route_top(zvrf->fec_table[af]); rn;
+		     rn = route_next(rn)) {
+			if (!rn->info)
+				continue;
+			fec = rn->info;
+			fec_change_update_lsp(zvrf, fec, MPLS_INVALID_LABEL,
+					      true);
+		}
+	}
+}
+
 /*
  * Update all registered clients about this FEC. Caller should've updated
  * FEC and ensure no duplicate updates.
@@ -1398,7 +1453,31 @@ static int nhlfe_del(struct zebra_nhlfe *nhlfe)
 static void nhlfe_out_label_update(struct zebra_nhlfe *nhlfe,
 				   struct mpls_label_stack *nh_label)
 {
-	nhlfe->nexthop->nh_label->label[0] = nh_label->label[0];
+	struct mpls_label_stack *nh_label_tmp;
+	int i;
+
+	/* Enforce limit on label stack size */
+	if (nh_label->num_labels > MPLS_MAX_LABELS)
+		nh_label->num_labels = MPLS_MAX_LABELS;
+
+	/* Resize the array to accommodate the new label stack */
+	if (nh_label->num_labels > nhlfe->nexthop->nh_label->num_labels) {
+		nh_label_tmp = XREALLOC(MTYPE_NH_LABEL, nhlfe->nexthop->nh_label,
+					sizeof(struct mpls_label_stack) +
+						nh_label->num_labels *
+							sizeof(mpls_label_t));
+		if (nh_label_tmp) {
+			nhlfe->nexthop->nh_label = nh_label_tmp;
+			nhlfe->nexthop->nh_label->num_labels =
+				nh_label->num_labels;
+		} else
+			nh_label->num_labels =
+				nhlfe->nexthop->nh_label->num_labels;
+	}
+
+	/* Copy the label stack into the array */
+	for (i = 0; i < nh_label->num_labels; i++)
+		nhlfe->nexthop->nh_label->label[i] = nh_label->label[i];
 }
 
 static int mpls_lsp_uninstall_all(struct hash *lsp_table, struct zebra_lsp *lsp,
@@ -2117,7 +2196,7 @@ void zebra_mpls_process_dplane_notify(struct zebra_dplane_ctx *ctx)
 /*
  * Install dynamic LSP entry.
  */
-int zebra_mpls_lsp_install(struct zebra_vrf *zvrf, struct route_node *rn,
+void zebra_mpls_lsp_install(struct zebra_vrf *zvrf, struct route_node *rn,
 			   struct route_entry *re)
 {
 	struct route_table *table;
@@ -2125,23 +2204,20 @@ int zebra_mpls_lsp_install(struct zebra_vrf *zvrf, struct route_node *rn,
 
 	table = zvrf->fec_table[family2afi(PREFIX_FAMILY(&rn->p))];
 	if (!table)
-		return -1;
+		return;
 
 	/* See if there is a configured label binding for this FEC. */
 	fec = fec_find(table, &rn->p);
 	if (!fec || fec->label == MPLS_INVALID_LABEL)
-		return 0;
+		return;
 
 	/* We cannot install a label forwarding entry if local label is the
 	 * implicit-null label.
 	 */
 	if (fec->label == MPLS_LABEL_IMPLICIT_NULL)
-		return 0;
+		return;
 
-	if (lsp_install(zvrf, fec->label, rn, re))
+	lsp_install(zvrf, fec->label, rn, re);
-		return -1;
-
-	return 0;
 }
 
 /*
@@ -2345,7 +2421,7 @@ int zebra_mpls_fec_register(struct zebra_vrf *zvrf, struct prefix *p,
 	}
 
 	if (new_client || label_change)
-		return fec_change_update_lsp(zvrf, fec, old_label);
+		return fec_change_update_lsp(zvrf, fec, old_label, false);
 
 	return 0;
 }
@@ -2386,7 +2462,7 @@ int zebra_mpls_fec_unregister(struct zebra_vrf *zvrf, struct prefix *p,
 	    list_isempty(fec->client_list)) {
 		mpls_label_t old_label = fec->label;
 		fec->label = MPLS_INVALID_LABEL; /* reset */
-		fec_change_update_lsp(zvrf, fec, old_label);
+		fec_change_update_lsp(zvrf, fec, old_label, false);
 		fec_del(fec);
 	}
 
@@ -2556,7 +2632,7 @@ int zebra_mpls_static_fec_add(struct zebra_vrf *zvrf, struct prefix *p,
 		fec_update_clients(fec);
 
 		/* Update label forwarding entries appropriately */
-		ret = fec_change_update_lsp(zvrf, fec, old_label);
+		ret = fec_change_update_lsp(zvrf, fec, old_label, false);
 	}
 
 	return ret;
@@ -2609,7 +2685,7 @@ int zebra_mpls_static_fec_del(struct zebra_vrf *zvrf, struct prefix *p)
 	fec_update_clients(fec);
 
 	/* Update label forwarding entries appropriately */
-	return fec_change_update_lsp(zvrf, fec, old_label);
+	return fec_change_update_lsp(zvrf, fec, old_label, false);
 }
 
 /*

zebra/zebra_mpls.h

@@ -146,7 +146,7 @@ int zebra_mpls_write_label_block_config(struct vty *vty, struct zebra_vrf *vrf);
 /*
  * Install dynamic LSP entry.
  */
-int zebra_mpls_lsp_install(struct zebra_vrf *zvrf, struct route_node *rn,
+void zebra_mpls_lsp_install(struct zebra_vrf *zvrf, struct route_node *rn,
 			   struct route_entry *re);
 
 /*
@@ -256,6 +256,12 @@ void mpls_zapi_labels_process(bool add_p, struct zebra_vrf *zvrf,
 void zebra_mpls_zapi_labels_process(bool add_p, struct zebra_vrf *zvrf,
 				    const struct zapi_labels *zl);
 
+/*
+ * Upon reconfiguring nexthop-resolution updates, update the
+ * lsp entries accordingly.
+ */
+void zebra_mpls_fec_nexthop_resolution_update(struct zebra_vrf *zvrf);
+
 /*
  * Uninstall all NHLFEs bound to a single FEC.
  *

zebra/zebra_nb.c

@@ -883,6 +883,13 @@ const struct frr_yang_module_info frr_zebra_info = {
 				.modify = lib_vrf_zebra_netns_table_range_end_modify,
 			}
 		},
+		{
+			.xpath = "/frr-vrf:lib/vrf/frr-zebra:zebra/mpls/fec-nexthop-resolution",
+			.cbs = {
+				.modify = lib_vrf_zebra_mpls_fec_nexthop_resolution_modify,
+				.destroy = lib_vrf_zebra_mpls_fec_nexthop_resolution_destroy,
+			}
+		},
 		{
 			.xpath = "/frr-vrf:lib/vrf/frr-zebra:zebra/ribs/rib",
 			.cbs = {

zebra/zebra_nb.h

@@ -309,6 +309,10 @@ int lib_vrf_zebra_netns_table_range_create(struct nb_cb_create_args *args);
 int lib_vrf_zebra_netns_table_range_destroy(struct nb_cb_destroy_args *args);
 int lib_vrf_zebra_netns_table_range_start_modify(struct nb_cb_modify_args *args);
 int lib_vrf_zebra_netns_table_range_end_modify(struct nb_cb_modify_args *args);
+int lib_vrf_zebra_mpls_fec_nexthop_resolution_modify(
+	struct nb_cb_modify_args *args);
+int lib_vrf_zebra_mpls_fec_nexthop_resolution_destroy(
+	struct nb_cb_destroy_args *args);
 const void *lib_vrf_zebra_ribs_rib_get_next(struct nb_cb_get_next_args *args);
 int lib_vrf_zebra_ribs_rib_get_keys(struct nb_cb_get_keys_args *args);
 const void *

zebra/zebra_nb_config.c

@@ -3780,6 +3780,59 @@ int lib_vrf_zebra_netns_table_range_end_modify(struct nb_cb_modify_args *args)
 	return NB_OK;
 }
 
+/*
+ * XPath: /frr-vrf:lib/vrf/frr-zebra:zebra/mpls/fec-nexthop-resolution
+ */
+int lib_vrf_zebra_mpls_fec_nexthop_resolution_modify(
+	struct nb_cb_modify_args *args)
+{
+	struct vrf *vrf;
+	struct zebra_vrf *zvrf;
+	bool fec_nexthop_resolution;
+
+	if (args->event != NB_EV_APPLY)
+		return NB_OK;
+
+	vrf = nb_running_get_entry(args->dnode, NULL, true);
+	zvrf = vrf->info;
+
+	fec_nexthop_resolution = yang_dnode_get_bool(args->dnode, NULL);
+
+	if (zvrf->zebra_mpls_fec_nexthop_resolution == fec_nexthop_resolution)
+		return NB_OK;
+
+	zvrf->zebra_mpls_fec_nexthop_resolution = fec_nexthop_resolution;
+
+	zebra_mpls_fec_nexthop_resolution_update(zvrf);
+
+	return NB_OK;
+}
+
+int lib_vrf_zebra_mpls_fec_nexthop_resolution_destroy(
+	struct nb_cb_destroy_args *args)
+{
+	struct vrf *vrf;
+	struct zebra_vrf *zvrf;
+	bool fec_nexthop_resolution;
+
+	if (args->event != NB_EV_APPLY)
+		return NB_OK;
+
+	vrf = nb_running_get_entry(args->dnode, NULL, true);
+	zvrf = vrf->info;
+
+	fec_nexthop_resolution = DFLT_ZEBRA_IP_NHT_RESOLVE_VIA_DEFAULT;
+
+	if (zvrf->zebra_mpls_fec_nexthop_resolution == fec_nexthop_resolution)
+		return NB_OK;
+
+	zvrf->zebra_mpls_fec_nexthop_resolution = fec_nexthop_resolution;
+
+	zebra_mpls_fec_nexthop_resolution_update(zvrf);
+
+	return NB_OK;
+}
+
 /*
  * XPath: /frr-vrf:lib/vrf/frr-zebra:zebra/l3vni-id
  */

zebra/zebra_rib.c

@@ -651,8 +651,10 @@ struct route_entry *rib_lookup_ipv4(struct prefix_ipv4 *p, vrf_id_t vrf_id)
 int zebra_rib_labeled_unicast(struct route_entry *re)
 {
 	struct nexthop *nexthop = NULL;
+	struct zebra_vrf *zvrf = vrf_info_lookup(re->vrf_id);
 
-	if (re->type != ZEBRA_ROUTE_BGP)
+	if ((re->type != ZEBRA_ROUTE_BGP) &&
+	    !zvrf->zebra_mpls_fec_nexthop_resolution)
 		return 0;
 
 	for (ALL_NEXTHOPS(re->nhe->nhg, nexthop))

zebra/zebra_vrf.h

@@ -173,6 +173,7 @@ struct zebra_vrf {
 
 	bool zebra_rnh_ip_default_route;
 	bool zebra_rnh_ipv6_default_route;
+	bool zebra_mpls_fec_nexthop_resolution;
 };
 #define PROTO_RM_NAME(zvrf, afi, rtype) zvrf->proto_rm[afi][rtype].name
 #define NHT_RM_NAME(zvrf, afi, rtype) zvrf->nht_rm[afi][rtype].name