bgp keepalive and expired issues on bird 1.6.8

[Ondrej Zajicek]

On Wed, Sep 28, 2022 at 12:22:10PM +0900, 안상혁 via Bird-users wrote:
> Hello,
> 
> we have encountered some issues using bird 1.6.8
> 
> there are two issues :
> 
> 1) sometimes bird looks like doesn't handle neighbor's bgp keepalive
> messages.

It is good idea to check which are effective keepalive and hold timeouts
(in 'show protocols all'), they may be different from configured ones due
to negotiation. It was possible to configure BIRD to have shorter or
similar hold interval to keepalive interval.

Also did that happen during CPU/BIRD full load, or during regular operation?


> when we get bgp hold timer exprired issue,
> on tcpdump there are keepalive packets that neighbor physical router sent
> and the server replied.
> 
> but there is no "Got KEEPALIVE" messages on bird.log and bgp session closed
> after "Error: Hold timer expired" message.
> 
> 2) bgp session exprired less than bgp hold timer value.
> 
> we set BGP hold timer to 9 seconds, but bgp expired in 7 seconds

Note that BGP timers are randomized a bit (RFC 4271 section 10, although
RFC leaves out HoldTimer, we randomize it too), so that is expected.


> or we should upgrade to bird 2?

We would strongly suggest upgrading to bird 2.

-- 
Elen sila lumenn' omentielvo

Ondrej 'Santiago' Zajicek (email: santiago at crfreenet.org)
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"To err is human -- to blame it on a computer is even more so."