Hi all,
We are using Bird v2.0.2 as a route-server, and I have a question about the use
of i-BGP sessions on a Bird RS.
We have the following topology : 2 RS (RS1 and RS2) are connected to several
peers, and some of those peers are connected to only one RS.
In order to get the same amount of prefixes on both RS, a i-BGP session was
created between RS1 and RS2.
i-BGP
RS1 ----------------- RS2
| |
| |
Peer1 Peer2
This topology was working really well between a Bird 1.6.3 and a Cisco ASR, and
we were able to announce the prefixes without the RS AS
in the AS-Path and with the proper next-hop regardless of from where the
prefixes were learnt (RS1 or RS2).
To clarify, if Peer1 was peering with RS1, and learning the prefixes of
someone, Peer2, who was peering exclusively with RS2, Peer1 would get the
prefixes
with the as path starting with the AS of peer2 and the next-hop would be peer2
router IP.
We wanted to use the same topology with a Bird 2.0.2 in place of a ASR, but it
seems to be treating i-BGP prefixes differently. With a bird 2.0.2, Peer1 is
receiving
the prefixes from Peer2 however the prefixes are announced with the RS AS in
the AS path and the next hop is the RS1 IP, hence the prefixes were unusable by
Peer1.
We are using the following tweak to correct the next hop : the use of 'direct'
and 'gateway direct' has corrected the next hop IP.
Below an example of the configuration we used.
We still haven't found a solution for the AS path.
protocol bgp RS1 {
local as 65001;
neighbor 192.168.2.1 as 65001;
...
direct;
ipv4 {
import ...;
gateway direct;
export ...;
};
}
Since we never noticed this problem for bird 1.6.3, is this a different
behavior for Bird 2.0.2 ?
Or is there a better way to have the intended announcements on both RS ?
I-BGP sessions between RS are really handy in case of failure, and we would
like to keep this topology.
Kind regards,
Noémie
