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 <equinox@opensourcerouting.org>
4 files changed