Our VyOS config is relatively large:
- dozens of BGP sessions
- dozens of route-maps and prefix-lists
- potentially tens of thousands of entries in route-maps and prefix-lists (auto-generated via bgpq3)
After a reboot of a router (with multiple transit and peering sessions), we found numerous peerings would not come up. We still have a couple down, and they are showing as tripped because:
Connections established 1; dropped 1 Last reset 04:44:43, due to NOTIFICATION received (Cease/Maximum Number of Prefixes Reached)
Cloudflare NOC emailed to say:
- IP: 18.104.22.168 - Manchester, GB - Number of prefixes received when sessions went down: 401.
This seemed strange to us, because the affected peers above have the same prefix-list out and route-map out applied that they had before a reboot. And the same prefix-list out and route-map out as many other peers, so should only be receiving ~20 prefixes right now:
show ip bgp neigh 22.214.171.124 advertised-routes [snip] Total number of prefixes 14
I assume, therefore that just like in T944, the BGP neighbor is established before when any referenced route-map and prefix-list is configured.