Merge pull request #12340 from opensourcerouting/fix/rfc5549_vpn_set_ip_nexthop

bgpd: Allow overriding MPLS VPN next-hops via route-maps

19 files changed, 356 insertions, 22 deletions

diff --git a/bgpd/bgp_attr.h b/bgpd/bgp_attr.h
index bc82d0c6ed..a34da1a6de 100644
--- a/bgpd/bgp_attr.h
+++ b/bgpd/bgp_attr.h
@@ -344,6 +344,8 @@ struct attr {
 #define BATTR_RMAP_IPV6_PREFER_GLOBAL_CHANGED (1 << 6)
 #define BATTR_RMAP_LINK_BW_SET (1 << 7)
 #define BATTR_RMAP_L3VPN_ACCEPT_GRE (1 << 8)
+#define BATTR_RMAP_VPNV4_NHOP_CHANGED (1 << 9)
+#define BATTR_RMAP_VPNV6_GLOBAL_NHOP_CHANGED (1 << 10)
 
 /* Router Reflector related structure. */
 struct cluster_list {
@@ -473,20 +475,23 @@ extern void bgp_packet_mpunreach_end(struct stream *s, size_t attrlen_pnt);
 extern enum bgp_attr_parse_ret bgp_attr_nexthop_valid(struct peer *peer,
 						      struct attr *attr);
 
-static inline int bgp_rmap_nhop_changed(uint32_t out_rmap_flags,
-					uint32_t in_rmap_flags)
+static inline bool bgp_rmap_nhop_changed(uint32_t out_rmap_flags,
+					 uint32_t in_rmap_flags)
 {
-	return ((CHECK_FLAG(out_rmap_flags, BATTR_RMAP_NEXTHOP_PEER_ADDRESS)
-		 || CHECK_FLAG(out_rmap_flags, BATTR_RMAP_NEXTHOP_UNCHANGED)
-		 || CHECK_FLAG(out_rmap_flags, BATTR_RMAP_IPV4_NHOP_CHANGED)
-		 || CHECK_FLAG(out_rmap_flags,
-			       BATTR_RMAP_IPV6_GLOBAL_NHOP_CHANGED)
-		 || CHECK_FLAG(out_rmap_flags,
-			       BATTR_RMAP_IPV6_PREFER_GLOBAL_CHANGED)
-		 || CHECK_FLAG(out_rmap_flags, BATTR_RMAP_IPV6_LL_NHOP_CHANGED)
-		 || CHECK_FLAG(in_rmap_flags, BATTR_RMAP_NEXTHOP_UNCHANGED))
-			? 1
-			: 0);
+	return ((CHECK_FLAG(out_rmap_flags, BATTR_RMAP_NEXTHOP_PEER_ADDRESS) ||
+		 CHECK_FLAG(out_rmap_flags, BATTR_RMAP_NEXTHOP_UNCHANGED) ||
+		 CHECK_FLAG(out_rmap_flags, BATTR_RMAP_IPV4_NHOP_CHANGED) ||
+		 CHECK_FLAG(out_rmap_flags, BATTR_RMAP_VPNV4_NHOP_CHANGED) ||
+		 CHECK_FLAG(out_rmap_flags,
+			    BATTR_RMAP_VPNV6_GLOBAL_NHOP_CHANGED) ||
+		 CHECK_FLAG(out_rmap_flags,
+			    BATTR_RMAP_IPV6_GLOBAL_NHOP_CHANGED) ||
+		 CHECK_FLAG(out_rmap_flags,
+			    BATTR_RMAP_IPV6_PREFER_GLOBAL_CHANGED) ||
+		 CHECK_FLAG(out_rmap_flags, BATTR_RMAP_IPV6_LL_NHOP_CHANGED) ||
+		 CHECK_FLAG(in_rmap_flags, BATTR_RMAP_NEXTHOP_UNCHANGED))
+			? true
+			: false);
 }
 
 static inline uint32_t mac_mobility_seqnum(struct attr *attr)
diff --git a/bgpd/bgp_route.c b/bgpd/bgp_route.c
index 2ca9502545..d6e6fc952f 100644
--- a/bgpd/bgp_route.c
+++ b/bgpd/bgp_route.c
@@ -2583,8 +2583,8 @@ bool subgroup_announce_check(struct bgp_dest *dest, struct bgp_path_info *pi,
 
 			if (bgp_debug_update(NULL, p, subgrp->update_group, 0))
 				zlog_debug(
-					"%s: BGP_PATH_ANNC_NH_SELF, family=%s",
-					__func__, family2str(family));
+					"%s: %pFX BGP_PATH_ANNC_NH_SELF, family=%s",
+					__func__, p, family2str(family));
 			subgroup_announce_reset_nhop(family, attr);
 			nh_reset = true;
 		}
@@ -11714,6 +11714,9 @@ int bgp_show_table_rd(struct vty *vty, struct bgp *bgp, safi_t safi,
 			vty_out(vty,
 				"\nDisplayed  %ld routes and %ld total paths\n",
 				output_cum, total_cum);
+	} else {
+		if (use_json && output_cum == 0)
+			vty_out(vty, "{}\n");
 	}
 	return CMD_SUCCESS;
 }
diff --git a/bgpd/bgp_routemap.c b/bgpd/bgp_routemap.c
index b736e6c38a..9422469bca 100644
--- a/bgpd/bgp_routemap.c
+++ b/bgpd/bgp_routemap.c
@@ -3725,6 +3725,8 @@ route_set_vpnv4_nexthop(void *rule, const struct prefix *prefix, void *object)
 	path->attr->mp_nexthop_global_in = *address;
 	path->attr->mp_nexthop_len = BGP_ATTR_NHLEN_IPV4;
 
+	SET_FLAG(path->attr->rmap_change_flags, BATTR_RMAP_VPNV4_NHOP_CHANGED);
+
 	return RMAP_OKAY;
 }
 
@@ -3762,6 +3764,9 @@ route_set_vpnv6_nexthop(void *rule, const struct prefix *prefix, void *object)
 	       sizeof(struct in6_addr));
 	path->attr->mp_nexthop_len = BGP_ATTR_NHLEN_VPNV6_GLOBAL;
 
+	SET_FLAG(path->attr->rmap_change_flags,
+		 BATTR_RMAP_VPNV6_GLOBAL_NHOP_CHANGED);
+
 	return RMAP_OKAY;
 }
 
diff --git a/bgpd/bgp_updgrp.h b/bgpd/bgp_updgrp.h
index 56289d399d..ecd92a996e 100644
--- a/bgpd/bgp_updgrp.h
+++ b/bgpd/bgp_updgrp.h
@@ -88,6 +88,8 @@ typedef struct {
 #define BPKT_ATTRVEC_FLAGS_RMAP_IPV4_NH_CHANGED   (1 << 4)
 #define BPKT_ATTRVEC_FLAGS_RMAP_IPV6_GNH_CHANGED  (1 << 5)
 #define BPKT_ATTRVEC_FLAGS_RMAP_IPV6_LNH_CHANGED  (1 << 6)
+#define BPKT_ATTRVEC_FLAGS_RMAP_VPNV4_NH_CHANGED  (1 << 7)
+#define BPKT_ATTRVEC_FLAGS_RMAP_VPNV6_GNH_CHANGED (1 << 8)
 
 typedef struct bpacket_attr_vec_arr {
 	bpacket_attr_vec entries[BGP_ATTR_VEC_MAX];
diff --git a/bgpd/bgp_updgrp_packet.c b/bgpd/bgp_updgrp_packet.c
index 9de97cf060..b52d67ed3c 100644
--- a/bgpd/bgp_updgrp_packet.c
+++ b/bgpd/bgp_updgrp_packet.c
@@ -379,10 +379,11 @@ struct stream *bpacket_reformat_for_peer(struct bpacket *pkt,
 
 		route_map_sets_nh =
 			(CHECK_FLAG(vec->flags,
-				    BPKT_ATTRVEC_FLAGS_RMAP_IPV4_NH_CHANGED)
-			 || CHECK_FLAG(
-				 vec->flags,
-				 BPKT_ATTRVEC_FLAGS_RMAP_NH_PEER_ADDRESS));
+				    BPKT_ATTRVEC_FLAGS_RMAP_IPV4_NH_CHANGED) ||
+			 CHECK_FLAG(vec->flags,
+				    BPKT_ATTRVEC_FLAGS_RMAP_VPNV4_NH_CHANGED) ||
+			 CHECK_FLAG(vec->flags,
+				    BPKT_ATTRVEC_FLAGS_RMAP_NH_PEER_ADDRESS));
 
 		switch (nhlen) {
 		case BGP_ATTR_NHLEN_IPV4:
@@ -468,10 +469,12 @@ struct stream *bpacket_reformat_for_peer(struct bpacket *pkt,
 
 		route_map_sets_nh =
 			(CHECK_FLAG(vec->flags,
-				    BPKT_ATTRVEC_FLAGS_RMAP_IPV6_GNH_CHANGED)
-			 || CHECK_FLAG(
+				    BPKT_ATTRVEC_FLAGS_RMAP_IPV6_GNH_CHANGED) ||
+			 CHECK_FLAG(
 				 vec->flags,
-				 BPKT_ATTRVEC_FLAGS_RMAP_NH_PEER_ADDRESS));
+				 BPKT_ATTRVEC_FLAGS_RMAP_VPNV6_GNH_CHANGED) ||
+			 CHECK_FLAG(vec->flags,
+				    BPKT_ATTRVEC_FLAGS_RMAP_NH_PEER_ADDRESS));
 
 		/*
 		 * The logic here is rather similar to that for IPv4, the
@@ -1276,6 +1279,15 @@ bpacket_vec_arr_inherit_attr_flags(struct bpacket_attr_vec_arr *vecarr,
 		SET_FLAG(vecarr->entries[BGP_ATTR_VEC_NH].flags,
 			 BPKT_ATTRVEC_FLAGS_RMAP_IPV6_GNH_CHANGED);
 
+	if (CHECK_FLAG(attr->rmap_change_flags, BATTR_RMAP_VPNV4_NHOP_CHANGED))
+		SET_FLAG(vecarr->entries[BGP_ATTR_VEC_NH].flags,
+			 BPKT_ATTRVEC_FLAGS_RMAP_VPNV4_NH_CHANGED);
+
+	if (CHECK_FLAG(attr->rmap_change_flags,
+		       BATTR_RMAP_VPNV6_GLOBAL_NHOP_CHANGED))
+		SET_FLAG(vecarr->entries[BGP_ATTR_VEC_NH].flags,
+			 BPKT_ATTRVEC_FLAGS_RMAP_VPNV6_GNH_CHANGED);
+
 	if (CHECK_FLAG(attr->rmap_change_flags,
 		       BATTR_RMAP_IPV6_LL_NHOP_CHANGED))
 		SET_FLAG(vecarr->entries[BGP_ATTR_VEC_NH].flags,
diff --git a/tests/topotests/bgp_vpn_5549_route_map/__init__.py b/tests/topotests/bgp_vpn_5549_route_map/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/tests/topotests/bgp_vpn_5549_route_map/__init__.py
diff --git a/tests/topotests/bgp_vpn_5549_route_map/cpe1/bgpd.conf b/tests/topotests/bgp_vpn_5549_route_map/cpe1/bgpd.conf
new file mode 100644
index 0000000000..013cd8c258
--- /dev/null
+++ b/tests/topotests/bgp_vpn_5549_route_map/cpe1/bgpd.conf
@@ -0,0 +1,9 @@
+router bgp 65000
+ no bgp ebgp-requires-policy
+ neighbor 192.168.1.2 remote-as external
+ neighbor 192.168.1.2 timers 1 3
+ neighbor 192.168.1.2 timers connect 1
+ address-family ipv4 unicast
+  redistribute connected
+ exit-address-family
+!
diff --git a/tests/topotests/bgp_vpn_5549_route_map/cpe1/zebra.conf b/tests/topotests/bgp_vpn_5549_route_map/cpe1/zebra.conf
new file mode 100644
index 0000000000..49dcfc3b02
--- /dev/null
+++ b/tests/topotests/bgp_vpn_5549_route_map/cpe1/zebra.conf
@@ -0,0 +1,9 @@
+!
+interface lo
+ ip address 172.16.255.1/32
+!
+interface cpe1-eth0
+ ip address 192.168.1.1/24
+!
+ip forwarding
+!
diff --git a/tests/topotests/bgp_vpn_5549_route_map/cpe2/bgpd.conf b/tests/topotests/bgp_vpn_5549_route_map/cpe2/bgpd.conf
new file mode 100644
index 0000000000..d65d507bf4
--- /dev/null
+++ b/tests/topotests/bgp_vpn_5549_route_map/cpe2/bgpd.conf
@@ -0,0 +1,6 @@
+router bgp 65000
+ no bgp ebgp-requires-policy
+ neighbor 192.168.2.2 remote-as external
+ neighbor 192.168.2.2 timers 1 3
+ neighbor 192.168.2.2 timers connect 1
+!
diff --git a/tests/topotests/bgp_vpn_5549_route_map/cpe2/zebra.conf b/tests/topotests/bgp_vpn_5549_route_map/cpe2/zebra.conf
new file mode 100644
index 0000000000..a47319e45f
--- /dev/null
+++ b/tests/topotests/bgp_vpn_5549_route_map/cpe2/zebra.conf
@@ -0,0 +1,6 @@
+!
+interface cpe2-eth0
+ ip address 192.168.2.1/24
+!
+ip forwarding
+!
diff --git a/tests/topotests/bgp_vpn_5549_route_map/pe1/bgpd.conf b/tests/topotests/bgp_vpn_5549_route_map/pe1/bgpd.conf
new file mode 100644
index 0000000000..93da025463
--- /dev/null
+++ b/tests/topotests/bgp_vpn_5549_route_map/pe1/bgpd.conf
@@ -0,0 +1,38 @@
+router bgp 65001
+ bgp router-id 10.10.10.10
+ no bgp ebgp-requires-policy
+ no bgp default ipv4-unicast
+ neighbor 2001:db8:1::2 remote-as internal
+ neighbor 2001:db8:1::2 update-source 2001:db8:1::1
+ neighbor 2001:db8:1::2 timers 1 3
+ neighbor 2001:db8:1::2 timers connect 1
+ neighbor 2001:db8:1::2 capability extended-nexthop
+ address-family ipv4 vpn
+  neighbor 2001:db8:1::2 activate
+  neighbor 2001:db8:1::2 route-map pe2 out
+ exit-address-family
+!
+router bgp 65001 vrf RED
+ bgp router-id 192.168.1.2
+ no bgp ebgp-requires-policy
+ neighbor 192.168.1.1 remote-as external
+ neighbor 192.168.1.1 timers 1 3
+ neighbor 192.168.1.1 timers connect 1
+ address-family ipv4 unicast
+  label vpn export 1111
+  rd vpn export 192.168.1.2:2
+  rt vpn import 192.168.2.2:2 192.168.1.2:2
+  rt vpn export 192.168.1.2:2
+  export vpn
+  import vpn
+ exit-address-family
+!
+ip prefix-list cpe1 seq 5 permit 172.16.255.1/32
+!
+route-map pe2 permit 10
+ match ip address prefix-list cpe1
+ set ipv6 vpn next-hop 2001:db8::1
+!
+route-map pe2 permit 20
+exit
+!
diff --git a/tests/topotests/bgp_vpn_5549_route_map/pe1/ldpd.conf b/tests/topotests/bgp_vpn_5549_route_map/pe1/ldpd.conf
new file mode 100644
index 0000000000..fb40f06fa7
--- /dev/null
+++ b/tests/topotests/bgp_vpn_5549_route_map/pe1/ldpd.conf
@@ -0,0 +1,10 @@
+mpls ldp
+ router-id 10.10.10.10
+ !
+ address-family ipv4
+  discovery transport-address 10.10.10.10
+  !
+  interface pe1-eth1
+  !
+ !
+!
diff --git a/tests/topotests/bgp_vpn_5549_route_map/pe1/ospf6d.conf b/tests/topotests/bgp_vpn_5549_route_map/pe1/ospf6d.conf
new file mode 100644
index 0000000000..0053d1ecb5
--- /dev/null
+++ b/tests/topotests/bgp_vpn_5549_route_map/pe1/ospf6d.conf
@@ -0,0 +1,12 @@
+!
+interface lo
+ ipv6 ospf6 area 0
+!
+interface pe1-eth1
+ ipv6 ospf6 area 0
+ ipv6 ospf6 hello-interval 1
+ ipv6 ospf6 dead-interval 3
+!
+router ospf6
+ ospf6 router-id 10.10.10.10
+!
diff --git a/tests/topotests/bgp_vpn_5549_route_map/pe1/zebra.conf b/tests/topotests/bgp_vpn_5549_route_map/pe1/zebra.conf
new file mode 100644
index 0000000000..da91055135
--- /dev/null
+++ b/tests/topotests/bgp_vpn_5549_route_map/pe1/zebra.conf
@@ -0,0 +1,14 @@
+!
+interface lo
+ ip address 10.10.10.10/32
+ ipv6 address 2001:db8:1::1/128
+!
+interface pe1-eth0 vrf RED
+ ip address 192.168.1.2/24
+!
+interface pe1-eth1
+ ip address 10.0.1.1/24
+ ipv6 address 2001:db8::1/64
+!
+ip forwarding
+!
diff --git a/tests/topotests/bgp_vpn_5549_route_map/pe2/bgpd.conf b/tests/topotests/bgp_vpn_5549_route_map/pe2/bgpd.conf
new file mode 100644
index 0000000000..6db1eef993
--- /dev/null
+++ b/tests/topotests/bgp_vpn_5549_route_map/pe2/bgpd.conf
@@ -0,0 +1,29 @@
+router bgp 65001
+ bgp router-id 10.10.10.20
+ no bgp ebgp-requires-policy
+ no bgp default ipv4-unicast
+ neighbor 2001:db8:1::1 remote-as internal
+ neighbor 2001:db8:1::1 update-source 2001:db8:1::2
+ neighbor 2001:db8:1::1 timers 1 3
+ neighbor 2001:db8:1::1 timers connect 1
+ neighbor 2001:db8:1::1 capability extended-nexthop
+ address-family ipv4 vpn
+  neighbor 2001:db8:1::1 activate
+ exit-address-family
+!
+router bgp 65001 vrf RED
+ bgp router-id 192.168.2.2
+ no bgp ebgp-requires-policy
+ neighbor 192.168.2.1 remote-as external
+ neighbor 192.168.2.1 timers 1 3
+ neighbor 192.168.2.1 timers connect 1
+ address-family ipv4 unicast
+  label vpn export 2222
+  rd vpn export 192.168.2.2:2
+  rt vpn import 192.168.2.2:2 192.168.1.2:2
+  rt vpn export 192.168.2.2:2
+  export vpn
+  import vpn
+ exit-address-family
+!
+
diff --git a/tests/topotests/bgp_vpn_5549_route_map/pe2/ldpd.conf b/tests/topotests/bgp_vpn_5549_route_map/pe2/ldpd.conf
new file mode 100644
index 0000000000..e2b5359993
--- /dev/null
+++ b/tests/topotests/bgp_vpn_5549_route_map/pe2/ldpd.conf
@@ -0,0 +1,10 @@
+mpls ldp
+ router-id 10.10.10.20
+ !
+ address-family ipv4
+  discovery transport-address 10.10.10.20
+  !
+  interface pe2-eth0
+  !
+ !
+!
diff --git a/tests/topotests/bgp_vpn_5549_route_map/pe2/ospf6d.conf b/tests/topotests/bgp_vpn_5549_route_map/pe2/ospf6d.conf
new file mode 100644
index 0000000000..f79bb4f5f7
--- /dev/null
+++ b/tests/topotests/bgp_vpn_5549_route_map/pe2/ospf6d.conf
@@ -0,0 +1,12 @@
+!
+interface lo
+ ipv6 ospf6 area 0
+!
+interface pe2-eth0
+ ipv6 ospf6 area 0
+ ipv6 ospf6 hello-interval 1
+ ipv6 ospf6 dead-interval 3
+!
+router ospf6
+ ospf6 router-id 10.10.10.20
+!
diff --git a/tests/topotests/bgp_vpn_5549_route_map/pe2/zebra.conf b/tests/topotests/bgp_vpn_5549_route_map/pe2/zebra.conf
new file mode 100644
index 0000000000..19ef7bf911
--- /dev/null
+++ b/tests/topotests/bgp_vpn_5549_route_map/pe2/zebra.conf
@@ -0,0 +1,14 @@
+!
+interface lo
+ ip address 10.10.10.20/32
+ ipv6 address 2001:db8:1::2/128
+!
+interface pe2-eth1 vrf RED
+ ip address 192.168.2.2/24
+!
+interface pe2-eth0
+ ip address 10.0.1.2/24
+ ipv6 address 2001:db8::2/64
+!
+ip forwarding
+!
diff --git a/tests/topotests/bgp_vpn_5549_route_map/test_bgp_vpn_5549_route_map.py b/tests/topotests/bgp_vpn_5549_route_map/test_bgp_vpn_5549_route_map.py
new file mode 100644
index 0000000000..e567d3654f
--- /dev/null
+++ b/tests/topotests/bgp_vpn_5549_route_map/test_bgp_vpn_5549_route_map.py
@@ -0,0 +1,138 @@
+#!/usr/bin/env python
+
+#
+# Copyright (c) 2022 by
+# Donatas Abraitis <donatas@opensourcerouting.org>
+#
+# 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 we can override VPN underlay next-hop from PE1 to PE2.
+"""
+
+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):
+    tgen.add_router("cpe1")
+    tgen.add_router("cpe2")
+    tgen.add_router("pe1")
+    tgen.add_router("pe2")
+
+    switch = tgen.add_switch("s1")
+    switch.add_link(tgen.gears["cpe1"])
+    switch.add_link(tgen.gears["pe1"])
+
+    switch = tgen.add_switch("s2")
+    switch.add_link(tgen.gears["pe1"])
+    switch.add_link(tgen.gears["pe2"])
+
+    switch = tgen.add_switch("s3")
+    switch.add_link(tgen.gears["pe2"])
+    switch.add_link(tgen.gears["cpe2"])
+
+
+def setup_module(mod):
+    tgen = Topogen(build_topo, mod.__name__)
+    tgen.start_topology()
+
+    pe1 = tgen.gears["pe1"]
+    pe2 = tgen.gears["pe2"]
+
+    pe1.run("ip link add RED type vrf table 1001")
+    pe1.run("ip link set up dev RED")
+    pe2.run("ip link add RED type vrf table 1001")
+    pe2.run("ip link set up dev RED")
+    pe1.run("ip link set pe1-eth0 master RED")
+    pe2.run("ip link set pe2-eth1 master RED")
+
+    pe1.run("sysctl -w net.ipv4.ip_forward=1")
+    pe2.run("sysctl -w net.ipv4.ip_forward=1")
+    pe1.run("sysctl -w net.mpls.conf.pe1-eth0.input=1")
+    pe2.run("sysctl -w net.mpls.conf.pe2-eth1.input=1")
+
+    router_list = tgen.routers()
+
+    for i, (rname, router) in enumerate(router_list.items(), 1):
+        router.load_config(
+            TopoRouter.RD_ZEBRA, os.path.join(CWD, "{}/zebra.conf".format(rname))
+        )
+        router.load_config(
+            TopoRouter.RD_BGP, os.path.join(CWD, "{}/bgpd.conf".format(rname))
+        )
+        router.load_config(
+            TopoRouter.RD_OSPF6, os.path.join(CWD, "{}/ospf6d.conf".format(rname))
+        )
+        router.load_config(
+            TopoRouter.RD_LDP, os.path.join(CWD, "{}/ldpd.conf".format(rname))
+        )
+
+    tgen.start_router()
+
+
+def teardown_module(mod):
+    tgen = get_topogen()
+    tgen.stop_topology()
+
+
+def test_bgp_vpn_5549():
+    tgen = get_topogen()
+
+    pe2 = tgen.gears["pe2"]
+
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+
+    def _bgp_vpn_nexthop_changed():
+        output = json.loads(pe2.vtysh_cmd("show bgp ipv4 vpn json"))
+        expected = {
+            "routes": {
+                "routeDistinguishers": {
+                    "192.168.1.2:2": {
+                        "172.16.255.1/32": [
+                            {"valid": True, "nexthops": [{"ip": "2001:db8::1"}]}
+                        ],
+                        "192.168.1.0/24": [
+                            {"valid": True, "nexthops": [{"ip": "2001:db8:1::1"}]}
+                        ],
+                    }
+                }
+            }
+        }
+        return topotest.json_cmp(output, expected)
+
+    test_func = functools.partial(_bgp_vpn_nexthop_changed)
+    _, result = topotest.run_and_expect(test_func, None, count=60, wait=0.5)
+    assert result is None, "Failed overriding IPv6 next-hop for VPN underlay"
+
+
+if __name__ == "__main__":
+    args = ["-s"] + sys.argv[1:]
+    sys.exit(pytest.main(args))