BGP reload routes issue

[David Petera]

Hii Derco,

you're right, that is a bug for sure!

It has been fixed and you can take a look at the details in commit 
message (basically you were right))
Link here: 
https://gitlab.nic.cz/labs/bird/-/commit/3a34912eb88e0b8ac061962362e1322bfce34ecd

The patch will be included in the upcoming two v3 releases (v3.2.1 and 
v3.1.6) in less then a week.

Thanks a lot for the catch!
David

David Petera (he/him) | BIRD Tech Support | CZ.NIC, z.s.p.o.

On 3/26/26 20:02, Derco Sportel via Bird-users wrote:
> Hello,
>
> We've been relying on bird heavily in our DC and basically all of our 
> servers use bird. All server advertise /32 addresses using BGP toward 
> the network and we use BFD for fast-fail. Lately we have observed some 
> issues with bird reloads where some neighbors report reload failed. 
> After investigation it looks as if the reload fails if the following 
> conditions have beex`n met:
>
> 1.
>     BGP sessions were established
> 2.
>     BGP flapped for $reason (router reload, BFD flap, other)
>
> After this, even though the BGP sessions are there, the Route 
> refresh capability is no longer possible.
> A restart of bird solves the problem.
>
> After investigation we suspect this is caused by the combination of 
> these parts of the code:
> https://github.com/CZ-NIC/bird/blob/9d509f232eaf04f707f51fd2368841d899ab8afc/proto/bgp/bgp.c#L1258 and 
> https://github.com/CZ-NIC/bird/blob/9d509f232eaf04f707f51fd2368841d899ab8afc/proto/bgp/bgp.c#L2917
>
> Our current install is version 3.2.0, though we have also observed 
> route refresh issues with prior 3.x versions.
>
> The bgp_init creates the object with reload routes, but a bgp_stop 
> makes it NULL. A bgp_start just starts the BGP session, but as the 
> reload_routes is NULL we loose the Route refresh capability.
>
> We might be completely off track here, and this might very well be 
> intended behavior, though we do suspect this to be wrong. Can someone 
> have a look at this and tell us if this is a bug or a feature?
>
> Regards,
>
> Derco Sportel | System Engineer Networking | https://bol.com 
> <https://bol.com/>
>
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