bgp announce default route to lower router, what is the bird version of default-originate / default-information orginate?

Luis Ressel aranea at aixah.de
Fri Oct 20 13:06:21 CEST 2017


Hello Richard,

Your approach looks good. If you don't want to hardcode net = 0.0.0.0/0
in the filter, you could replace that check with "source = RTS_STATIC"
if your config doesn't use the static protocol for anything else. If
you need more static routes (for example to announce the local network
to other BGP peers, I'd use an explicit protocol name, like this:

protocol static static_default {
route 0.0.0.0/0 unreachable;
}

Then, the export filter could check for proto = "static_default".

Both of these approaches have the slight advantage that you can later
add a ::/0 route, too, without needing to update any filters.

Of course, as Vladislav pointed out, you should also update your export
filters for all other peers so you don't export a default route to
them, but I'm sure you're already doing this.

By the way, I should mention that using the static protocol for this
results in one limitation: You'll /always/ export a default route to
your client, even if all other peerings happen to be down and your
router doesn't have any internet connectivity at all. If the client's
only route to the internet goes through your router, this is of course
not an issue, but if the client has other routes it could fail over to,
you'll need a more complex setup.

Regards,
Luis Ressel
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