bgpd: Override peer's TTL only if peer-group is configured with TTL

When a peer-group is configured for an already configured eBGP neighbor,
ebgp-multihop command is removed for that peer.

This fix remains configured peer's ebgp-multihop value if peer-group does
not have ebgp-multihop configured.

!
router bgp 100
 neighbor A8 peer-group
 neighbor A9 peer-group
 neighbor A9 ebgp-multihop 12
 neighbor 3.3.3.3 remote-as 123
 neighbor 3.3.3.3 ebgp-multihop 255
 neighbor 4.4.4.4 remote-as 123
 !

spine1-debian-9#
spine1-debian-9# conf
spine1-debian-9(config)# router bgp 100
spine1-debian-9(config-router)# neighbor 3.3.3.3 peer-group A8
spine1-debian-9(config-router)# do sh run

!
router bgp 100
 neighbor A8 peer-group
 neighbor A9 peer-group
 neighbor A9 ebgp-multihop 12
 neighbor 3.3.3.3 remote-as 123
 neighbor 3.3.3.3 peer-group A8
 neighbor 3.3.3.3 ebgp-multihop 255
 neighbor 4.4.4.4 remote-as 123
!

spine1-debian-9(config-router)# neighbor 4.4.4.4 peer-group A9
spine1-debian-9(config-router)# do sh run

!
router bgp 100
 neighbor A8 peer-group
 neighbor A9 peer-group
 neighbor A9 ebgp-multihop 12
 neighbor 3.3.3.3 remote-as 123
 neighbor 3.3.3.3 peer-group A8
 neighbor 3.3.3.3 ebgp-multihop 255
 neighbor 4.4.4.4 remote-as 123
 neighbor 4.4.4.4 peer-group A9
!

Signed-off-by: Donatas Abraitis <donatas.abraitis@gmail.com>

diff --git a/bgpd/bgpd.c b/bgpd/bgpd.c
index bd5655a8051ee4606365c960416a56f9f00d5102..66c1e623a08305526a817e094c26013d0ad7a433 100644 (file)
--- a/bgpd/bgpd.c
+++ b/bgpd/bgpd.c
@@ -1588,7 +1588,7 @@ struct peer *peer_create(union sockunion *su, const char *conf_if,
        peer->readtime = peer->resettime = bgp_clock();
 
        /* Default TTL set. */
-       peer->ttl = (peer->sort == BGP_PEER_IBGP) ? MAXTTL : 1;
+       peer->ttl = (peer->sort == BGP_PEER_IBGP) ? MAXTTL : BGP_DEFAULT_TTL;
 
        SET_FLAG(peer->flags, PEER_FLAG_CONFIG_NODE);
 
@@ -1675,7 +1675,7 @@ void peer_as_change(struct peer *peer, as_t as, int as_specified)
        if (peer_sort(peer) == BGP_PEER_IBGP)
                peer->ttl = MAXTTL;
        else if (type == BGP_PEER_IBGP)
-               peer->ttl = 1;
+               peer->ttl = BGP_DEFAULT_TTL;
 
        /* reflector-client reset */
        if (peer_sort(peer) != BGP_PEER_IBGP) {
@@ -2435,7 +2435,7 @@ struct peer_group *peer_group_get(struct bgp *bgp, const char *name)
        group->conf->host = XSTRDUP(MTYPE_BGP_PEER_HOST, name);
        group->conf->group = group;
        group->conf->as = 0;
-       group->conf->ttl = 1;
+       group->conf->ttl = BGP_DEFAULT_TTL;
        group->conf->gtsm_hops = 0;
        group->conf->v_routeadv = BGP_DEFAULT_EBGP_ROUTEADV;
        SET_FLAG(group->conf->sflags, PEER_STATUS_GROUP);
@@ -2460,8 +2460,9 @@ static void peer_group2peer_config_copy(struct peer_group *group,
        if (!CHECK_FLAG(peer->flags_override, PEER_FLAG_LOCAL_AS))
                peer->change_local_as = conf->change_local_as;
 
-       /* TTL */
-       peer->ttl = conf->ttl;
+       /* If peer-group has configured TTL then override it */
+       if (conf->ttl != BGP_DEFAULT_TTL)
+               peer->ttl = conf->ttl;
 
        /* GTSM hops */
        peer->gtsm_hops = conf->gtsm_hops;
@@ -4383,7 +4384,7 @@ int peer_ebgp_multihop_unset(struct peer *peer)
        if (peer_group_active(peer))
                peer->ttl = peer->group->conf->ttl;
        else
-               peer->ttl = 1;
+               peer->ttl = BGP_DEFAULT_TTL;
 
        if (!CHECK_FLAG(peer->sflags, PEER_STATUS_GROUP)) {
                if (BGP_IS_VALID_STATE_FOR_NOTIF(peer->status))
@@ -4397,7 +4398,7 @@ int peer_ebgp_multihop_unset(struct peer *peer)
                        if (peer->sort == BGP_PEER_IBGP)
                                continue;
 
-                       peer->ttl = 1;
+                       peer->ttl = BGP_DEFAULT_TTL;
 
                        if (peer->fd >= 0) {
                                if (BGP_IS_VALID_STATE_FOR_NOTIF(peer->status))

diff --git a/bgpd/bgpd.h b/bgpd/bgpd.h
index 88246ae24b16a03df12acb5dfc230b416f071f51..865f5a2b68fb868f2cc8f40c45a0a413b477623a 100644 (file)
--- a/bgpd/bgpd.h
+++ b/bgpd/bgpd.h
@@ -627,6 +627,8 @@ struct bgp_nexthop {
 #define RMAP_OUT 1
 #define RMAP_MAX 2
 
+#define BGP_DEFAULT_TTL 1
+
 #include "filter.h"
 
 /* BGP filter structure. */