On Fri, 2022-10-14 at 16:10 +0200, Ondrej Zajicek wrote:
On Fri, Oct 14, 2022 at 01:28:27AM +0200, Garri Djavadyan via Bird- users wrote:
Hello everyone,
I noticed that the legacy Bird version behaves strangely while it is in an enhanced route-refreshing process, but I am not sure whether it is a known/expected behaviour for version 1.6.8. Namely, right after a 1.6.8 peers sends a BoRR message, it also sends withdrawals for the prefixes it received from that same peer. For example, below is the output from two Bird peers (1.6.8 and 2.0.10):
So, I am just curious if it is a bug or some architectural limitation of Bird-1.6. If I understand correctly, there are two problems here:
Hello
Yes, it is expected, although unnecessary. The route feeding code just send updates or withdraws and does not consider whether it is initial feed, regular route refresh, or enhanced route-refresh.
In BIRD 2.0.10, we keep a bitmap of routes that were announced, so we do not send withdraws for ones that were not announced before, but we would AFAIK send unnecessary withdraws during enhanced route-refresh (for routes that were announced before).
Indeed, BIRD 2.0.10 also sends redundant/explicit withdrawals for previously announced prefixes during ERR. Thank you for the details, Ondrej. Garri