Hello Pouria, On Wed, Aug 26, 2026 at 08:28:40PM +0330, Pouria Mousavizadeh Tehrani wrote:

I'm trying to switch a FreeBSD IXP router from another routing daemon to BIRD for BGP. I already have OSPF running on the same system, and BIRD works without any problems.

However, after starting BIRD and establishing/attempting to establish BGP sessions, I get the following error multiple times in `bird.log`:

[0001] <BUG> Assertion 'ipa_zero(s->saddr) || ipa_zero(s->daddr) || (ipa_is_ip4(s->saddr) == ipa_is_ip4(s->daddr))' failed at sysdep/unix/io.c:1767

This is a very specific crash happening when two ends of a connection have different address families. This should not happen at all and I'd like to ask you for your config file and a tcpdump (you may send it privately) so that we can try to find out where the discrepancy slipped through and why.

Many seconds after these errors, BIRD crashes.

We assumed that this wouldn't happen but hoped that it could be a recoverable error. Maybe that's not the case.

BIRD version: 3.3.2 (the same issue also occurs with older versions) FreeBSD version: 16.0-CURRENT (same with 15.1-RELEASE)

Thanks for reporting the version, it helps pin down the actual code logic involved. Have a nice day! -- Maria Matejka (she/her) | BIRD Team Leader | CZ.NIC, z.s.p.o.