BGP multi-homed peering issue..

[Ondrej Zajicek]

On Thu, Oct 06, 2011 at 06:05:12PM -0500, Michael Vallaly wrote:
> 
> Fellow bird users,
> 
> I currently have a single router with two upstream eBGP sessions to two
> separate ISPs. IE: 
> 
>   ISP1 <---> Router <---> ISP2
> 
> I am attempting to advertise a public netblock to both of these ISPs
> simultaneously. I currently have a single kernel routing table
> (exterior) configured for the public netblock (203.0.113.0/24), below
> is a sample config.
> 
> I seem to have a problem in Bird 1.3.3 with this configuration where
> the netblock only gets advertised out one of the two upstream peers.

See https://git.nic.cz/redmine/projects/bird/wiki/BGP_example_2

> When I enable both ext_isp1 and ext_isp2 protocols simultaneously it
> seems the BGP advertisement only happens via one peer only, (not both as
> I expect / want). Does it make sense that this doesn't work as I expect?

Problem is that only the best route is propagated. If the best route is
filtered, second best route is not propagated.

-- 
Elen sila lumenn' omentielvo

Ondrej 'SanTiago' Zajicek (email: santiago at crfreenet.org)
OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net)
"To err is human -- to blame it on a computer is even more so."
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