redesigned version of bgp in bird2 changes the rs client behaviour

[Ondrej Zajicek]

On Tue, Nov 06, 2018 at 01:19:19PM +0100, Alexander Zubkov wrote:
> Can this be considered a bug and fixed so any "rs client" session would not
> receive prepend? Or current behaviour is relied on by some production
> systems?

Hi

The change was intentional (to be consistent with route reflector
behavior), but it is hard to say what is expected behavior and which one
makes more sense. AFAIK it is not specified anywhere and it rarely makes
sense to mix RS sessions with other sessions. This is not a first
complain (see [*]) for the new behavior, so we may roll it back, but
there are also cases where it makes sense - e.g. where IXP/RS is mixed
with upstream provider, so in the RS there are routes received from other
RS peers, which should not be prepended, and IBGP routes representing
upstream, which should be prepended.

IMHO the old behavior was inconsistent w.r.t. local routes - BIRD should
handle in the same way local routes and routes local to the AS received
from IBGP.

Could you make a case for either prepend or not-prepend behavior?
Should it be different for non-RS EBGP to RS EBGP vs IBGP to RS EBGP?

[*] https://www.mail-archive.com/bird-users@network.cz/msg03424.html

-- 
Elen sila lumenn' omentielvo

Ondrej 'Santiago' Zajicek (email: santiago at crfreenet.org)
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"To err is human -- to blame it on a computer is even more so."