BIRD incorrectly(?) detects whether a peer is directly connected

[Ondrej Zajicek]

On Wed, Feb 16, 2022 at 03:32:55AM +0100, Arsen Arsenović wrote:
> Good evening!
> 
> When configuring BGP on a site BIRD fails to recognize whether an IP is
> directly connected. It appears to scan over the list of interfaces and
> check whether their subnets contain the target IP instead of relying on
> the route table and checking whether the resulting route has a gateway
> attribute. This does not work in some edge cases (such as, in our case,
> the machine being configured for a /128 + a LAN route to avoid some
> Linux autoconfiguration)

Hello

That is true, but it is not limited to BGP peers, it also affects other
issues like next hop validation. Unfortunately it is not easily fixable.
It would require redesigning whole internal neighbor processing, which
is something that we plan to do, but there are currently tasks with
higher priority.

Also, for BGP peers, it can be workarounded by setting BGP as multihop 1.

-- 
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."