Review my BGP configuration

[Andre Nathan]

Hi again, Hans

I tried your suggested configuration. It worked almost perfectly, but I
had one problem.

My router's network interfaces are configured as follows:

  eth0: interface connected to a.b.0.0/23 network
  eth1: interface for eBGP and iBGP sessions

What happened was that my IP block is a.b.0.0/23, and therefore my
router has an IP address with a /23 netmask in eth0 (say, a.b.0.1/23).
However, I export two /24 blocks, a.b.0.0/24 and a.b.0.1/24. The router
learns these routes from the iBGP session, and since they are more
specific than the eth0 interface route, they'll be preferred when
compared to the eth0 interface route. So I ended up with a route to the
/23 via eth0 and two routes to the /24 blocks via eth1, with the iBGP
peer as the gateway.

My first thought is that I need another static protocol block in my
configuration:

protocol static {
  route a.b.0.0/24 via "eth0";
  route a.b.0.1/24 via "eth0";
}

Is that a solution to this situation? What's weird to me is that my
other router (the iBGP peer of the Bird router) is still running Quagga,
and it learns the same two /24 routes via iBGP but does not add them to
the kernel routing table. I'm wondering if Quagga is doing some kind of
filtering here behind the scenes that isn't done by default in Bird...

Thanks,
Andre
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