From 9d3f9705d8b386ccf006c106967c700141e5d049 Mon Sep 17 00:00:00 2001 From: Andrew Certain Date: Wed, 7 Nov 2012 23:50:07 +0000 Subject: bgpd: add replace-as modifier for BGP neighbor Added replace-as modifier for BGP neighbors when using local-as. If the replace-as modifier is specified, only the replacement AS as specified by the local-as modifier is prepended to the AS_PATH, not the process's AS. In bgp_attr.c, I decided that if (peer->change_local_as) { /* If replace-as is specified, we only use the change_local_as when advertising routes. */ if( ! CHECK_FLAG (peer->flags, PEER_FLAG_LOCAL_AS_REPLACE_AS) ) { aspath = aspath_add_seq (aspath, peer->local_as); } aspath = aspath_add_seq (aspath, peer->change_local_as); } else { aspath = aspath_add_seq (aspath, peer->local_as); } was clearer than the alternative that didn't duplicate the prepending of the process's AS: /* First, append the process local AS unless we have an alternate local_as * and we're replacing it (as opposed to just prepending it). */ if (! (peer->change_local_as && CHECK_FLAG (peer->flags, PEER_FLAG_LOCAL_AS_REPLACE_AS) ) ) { aspath = aspath_add_seq (aspath, peer->local_as); } if (peer->change_local_as) aspath = aspath_add_seq (aspath, peer->change_local_as); } But I could be convinced otherwise. Signed-off-by: David Lamparter --- bgpd/bgpd.c | 29 +++++++++++++++++++++++++---- 1 file changed, 25 insertions(+), 4 deletions(-) (limited to 'bgpd/bgpd.c') diff --git a/bgpd/bgpd.c b/bgpd/bgpd.c index 69c8c0a3..908bdd94 100644 --- a/bgpd/bgpd.c +++ b/bgpd/bgpd.c @@ -962,6 +962,7 @@ peer_as_change (struct peer *peer, as_t as) { peer->change_local_as = 0; UNSET_FLAG (peer->flags, PEER_FLAG_LOCAL_AS_NO_PREPEND); + UNSET_FLAG (peer->flags, PEER_FLAG_LOCAL_AS_REPLACE_AS); } } @@ -1830,6 +1831,7 @@ peer_group_bind (struct bgp *bgp, union sockunion *su, { group->conf->change_local_as = 0; UNSET_FLAG (peer->flags, PEER_FLAG_LOCAL_AS_NO_PREPEND); + UNSET_FLAG (peer->flags, PEER_FLAG_LOCAL_AS_REPLACE_AS); } } @@ -3405,7 +3407,7 @@ peer_allowas_in_unset (struct peer *peer, afi_t afi, safi_t safi) } int -peer_local_as_set (struct peer *peer, as_t as, int no_prepend) +peer_local_as_set (struct peer *peer, as_t as, int no_prepend, int replace_as) { struct bgp *bgp = peer->bgp; struct peer_group *group; @@ -3421,9 +3423,14 @@ peer_local_as_set (struct peer *peer, as_t as, int no_prepend) if (peer_group_active (peer)) return BGP_ERR_INVALID_FOR_PEER_GROUP_MEMBER; + if (peer->as == as) + return BGP_ERR_CANNOT_HAVE_LOCAL_AS_SAME_AS_REMOTE_AS; + if (peer->change_local_as == as && ((CHECK_FLAG (peer->flags, PEER_FLAG_LOCAL_AS_NO_PREPEND) && no_prepend) - || (! CHECK_FLAG (peer->flags, PEER_FLAG_LOCAL_AS_NO_PREPEND) && ! no_prepend))) + || (! CHECK_FLAG (peer->flags, PEER_FLAG_LOCAL_AS_NO_PREPEND) && ! no_prepend)) && + ((CHECK_FLAG (peer->flags, PEER_FLAG_LOCAL_AS_REPLACE_AS) && replace_as) + || (! CHECK_FLAG (peer->flags, PEER_FLAG_LOCAL_AS_REPLACE_AS) && ! replace_as))) return 0; peer->change_local_as = as; @@ -3432,6 +3439,11 @@ peer_local_as_set (struct peer *peer, as_t as, int no_prepend) else UNSET_FLAG (peer->flags, PEER_FLAG_LOCAL_AS_NO_PREPEND); + if (replace_as) + SET_FLAG (peer->flags, PEER_FLAG_LOCAL_AS_REPLACE_AS); + else + UNSET_FLAG (peer->flags, PEER_FLAG_LOCAL_AS_REPLACE_AS); + if (! CHECK_FLAG (peer->sflags, PEER_STATUS_GROUP)) { if (peer->status == Established) @@ -3455,6 +3467,11 @@ peer_local_as_set (struct peer *peer, as_t as, int no_prepend) else UNSET_FLAG (peer->flags, PEER_FLAG_LOCAL_AS_NO_PREPEND); + if (replace_as) + SET_FLAG (peer->flags, PEER_FLAG_LOCAL_AS_REPLACE_AS); + else + UNSET_FLAG (peer->flags, PEER_FLAG_LOCAL_AS_REPLACE_AS); + if (peer->status == Established) { peer->last_reset = PEER_DOWN_LOCAL_AS_CHANGE; @@ -3482,6 +3499,7 @@ peer_local_as_unset (struct peer *peer) peer->change_local_as = 0; UNSET_FLAG (peer->flags, PEER_FLAG_LOCAL_AS_NO_PREPEND); + UNSET_FLAG (peer->flags, PEER_FLAG_LOCAL_AS_REPLACE_AS); if (! CHECK_FLAG (peer->sflags, PEER_STATUS_GROUP)) { @@ -3502,6 +3520,7 @@ peer_local_as_unset (struct peer *peer) { peer->change_local_as = 0; UNSET_FLAG (peer->flags, PEER_FLAG_LOCAL_AS_NO_PREPEND); + UNSET_FLAG (peer->flags, PEER_FLAG_LOCAL_AS_REPLACE_AS); if (peer->status == Established) { @@ -4770,10 +4789,12 @@ bgp_config_write_peer (struct vty *vty, struct bgp *bgp, /* local-as. */ if (peer->change_local_as) if (! peer_group_active (peer)) - vty_out (vty, " neighbor %s local-as %u%s%s", addr, + vty_out (vty, " neighbor %s local-as %u%s%s%s", addr, peer->change_local_as, CHECK_FLAG (peer->flags, PEER_FLAG_LOCAL_AS_NO_PREPEND) ? - " no-prepend" : "", VTY_NEWLINE); + " no-prepend" : "", + CHECK_FLAG (peer->flags, PEER_FLAG_LOCAL_AS_REPLACE_AS) ? + " replace-as" : "", VTY_NEWLINE); /* Description. */ if (peer->desc) -- cgit v1.2.1