On Fri, 2019-03-01 at 13:23 +0100, Ondrej Zajicek wrote:
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On Fri, Mar 01, 2019 at 11:46:28AM +0000, Kenth Eriksson wrote:
We don't have multipath enabled in our kernel (CONFIG_IP_ROUTE_MULTIPATH). How does bird tell whether the kernel supports multipath? Probing run time via netlink? Didn't find any configure.ac option.
BIRD does not detect that. I don't know if there is a reasonable way how to detect it. Just disable ECMP in OSPF if your kernel does not support ECMP routes.
Ok, thanks for clarifying that. The manual gave me the impression that it was detected somehow since it has the following line:
"By default, ECMP is enabled if supported by Kernel"
OK, this is supposed to mean 'by Kernel protocol'. Kernel protocol supports ECMP on Linux, but not on BSD.
I rebuilt my kernel with multipath support, that does seem to remove the netlink warning logs. And now bird does push the prefix as a multipath to the kernel. Logs: bird> show route for 172.20.4.41 Table master4: 172.20.4.41/32 unicast [ospf1 13:03:37.891] I (145/10) [172.20.4.41] via 172.20.4.41 on p1-1-3-1-4 weight 1 via 172.20.4.41 on p1-1-1-1-2 weight 1 unicast [direct1 13:43:08.338] (100) dev p1-1-1-1-2 unicast [direct1 13:43:08.338] (100) dev p1-1-3-1-4 bird> kenth ~ # ip route ... 172.20.4.41 proto bird metric 32 nexthop via 172.20.4.41 dev p1-1-1-1-2 weight 1 nexthop via 172.20.4.41 dev p1-1-3-1-4 weight 1 kenth ~ #
-- Elen sila lumenn' omentielvo
Ondrej 'Santiago' Zajicek (email: santiago@crfreenet.org) OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net) "To err is human -- to blame it on a computer is even more so."