Hoi folks, At Coloclue AS8283, we upgraded from Bird1.6.8 to Bird2.0.12 this week. We use two separate processes, one for IPv4 and one for IPv6 - and 2.0.7 in Debian is missing the ability to select 'accept ipv4' and 'accept ipv6' in BFD, so we installed backports and version 2.0.12). I am wondering if Bird2 later than 2.0.7 perhaps has an optimization when swapping routes? I would expect a swap to be "delete + add" but I am seeing only "add with new nexthop" appear in Netlink. Considering the following topology with link names and OSPFv3 costs associated: dcg-1 bond0.130 ---- bond0.130 eun-2 | 2000 | enp1s0f3 enp1s0f2 | | | 10 10 | | | enp1s0f3 enp1s0f3 | 1000 | dcg-2 eno2.3469 ---- eno2.3469 eun-3 If I restart the OSPFv3 protocol, I see that the topology settles in the expected way. What I observed with bird 2.0.12 is that there is a deletion of the currently selected route followed by one addition, when the shortest path reveales (dcg1 - dcg2 - eun3 - eun2, ospf_metric1 is 1020, this is fine): root@dcg-1:~# birdc -s /run/bird/bird6.ctl restart ospf1 root@dcg-1:~# ip -6 monitor route | grep 2a02:898:0:300::3 Deleted 2a02:898:0:300::3 via fe80::669d:99ff:feb1:31af dev bond0.130 proto bird metric 32 pref medium 2a02:898:0:300::3 via fe80::669d:99ff:feb1:3910 dev enp1s0f3 proto bird metric 32 pref medium Now I lower the cost of the dcg-1 -- eun-2 link from 2000 to 100, so that it becomes preferred (cost ospf_metric is 120): root@dcg-1:~# birdc -s /run/bird/bird6.ctl reconfigure ospf1 root@dcg-1:~# ip -6 monitor route | grep 2a02:898:0:300::3 *[[ HERE ]]* 2a02:898:0:300::3 via fe80::669d:99ff:feb1:31af dev bond0.130 proto bird metric 32 pref medium I would expect this new addition of the installed route on bond0.130 to be *preceded by a deletion* of the previous route from enp1s0f3, but this is not the case (marked in red with [[ HERE ]]). To anyone's knowledge: *Has this behavior changed between 2.0.7 and 2.0.12 ?* groet, Pim -- Pim van Pelt <pim@ipng.nl> PBVP1-RIPE - http://www.ipng.nl/