Telia Not Withdrawing v6 Routes

Mon Nov 16 19:13:04 UTC 2020

----- On Nov 15, 2020, at 5:58 PM, Matt Corallo nanog at as397444.net wrote:

> Has anyone else experienced issues where Telia won't withdraw (though will
> happily accept an overriding) prefixes for the past week, at least?

I have seen issues like this in a network that I operated. In that particular
case, it was an internal ipv4 10/8 route which was withdrawn, along with a
few hundred other routes. The withdrawl was configured on a DC exit router,
in a Clos network with leaf, spine, and superspine. On the spine layer, I
observed that BGP withdrawls, although being received, were not processed
by the control plane. 

Further investigation and working with the TAC of the vendor, revealed that
on that particular platform, the BGP process would stop process withdrawls
in a very nasty race condition that was very difficult to reproduce.

This was the first (and so far only) time in my 20+ years of working with
BGP that I've observed such a weird bug. Since I operated the entire 
network, it was fairly easy to find the culprit. The why, took some more 
time.

If I were in your shoes, I'd ping Telia's NOC to see what's going on. I
would not be surprised if they'd be hitting a similar issue.

Thanks,

Sabri