On Mon, Dec 18, 2023 at 01:53:50PM +0100, Marko Cupać wrote: > On Sat, 16 Dec 2023 18:53:29 +0100 > Petr Ročkai <m.v0adg...@fixp.eu> wrote: > > > Hi, > > > > On Sat, Dec 16, 2023 at 06:37:54PM +0100, Marko Cupać wrote: > > > pass in on em0 from (em0:network) to <public> probability 50% > > > rtable 1 pass in on em0 from (em0:network) to <public> probability > > > 50% rtable 2 > > > > IIUIC these two only add up to 75% probability – you presumably want > > probability 50% on the second of the two (the first one then being a > > match for everything that the later rule doesn't take up). > > Thank you, I can confirm that your solution: > > pass in on em0 from (em0:network) to <public> rtable 1 > pass in on em0 from (em0:network) to <public> probability 50% rtable 2 > > ... results in what I was trying to achieve - it load balances over both > uplinks without any blocked packets as long as both uplinks are active. > > What OpenBSD FAQ https://www.openbsd.org/faq/faq6.html#Multipath says > for a bit different scenario applies to some extent for this one as > well: > > "It's worth noting that if an interface used by a multipath route goes > down (i.e., loses carrier), the kernel will still try to forward > packets using the route that points to that interface. This traffic > will of course be blackholed and end up going nowhere. It's highly > recommended to use ifstated(8) to check for unavailable interfaces and > adjust the routing table accordingly."
Uhm. This is not accurate. The kernel tracks interface state on routes and will not select a multipath route that is not considered UP. There is a smaller issue when there is no other multipath route. The lookup will select the route and not fall back to a less specific one that is still up. Could please someone update the FAQ? > ...except - if I'm not mistaken - ifstated should in this case adjust > pf ruleset instead of routing table. > > If so, would using anchors be the best way? Any working examples to > share? I used some simple ifstated rules but it is hard to wrap my head > around probability percentages for all the use cases - first link up, > second down and vice versa. > > Thank you in advance, > > -- > Before enlightenment - chop wood, draw water. > After enlightenment - chop wood, draw water. > > Marko Cupać > https://www.mimar.rs/ > -- :wq Claudio
