Hello!
Is there any way to filter a export route based on another BGP session
status?
No and it isn't in a short-term plan. The multithreaded version may get
some better API to do it, yet I won't promise anything specific.
For the sake of simplicity let’s say we have just two providers A and B,
and I only want to export some specific routes to B when A is down.
I can do it externally with a quite simple script (For example: Check if
the provider is down via CLI and if it’s down insert the routes I want
to export to a kernel table and export that to provider B) but it would
be nice if I could do it directly in Bird.
I’ve been scratching my head around this, but unless there is something
like if proto.A == down on the filters I don’t really see how to do it
(Or maybe some way to raise a global flag based on if I’m receiving
routes via provider B, but I don’t think that can’t be done either.)
I'd suggest to depreference the B-route by AS path stuffing, like 3-5
times or so, to effectively force usage of the other route while still
exporting it.
Maria
