Hello list,
I've been trying to figure out how to make equal-cost multipath
routing work, with no luck. Asked on the LARTC list with no success,
and attempts to contact the two authors privately yielded one bounce
while the other declined to answer in private and pointed me to this
list. So I'll just include the rest of the mail I sent them here
(after doing a search-and-replace on the first three octets of all
addresses, I'm a bit paranoid), hopefully someone has some suggestions
for me...
I'm using 2.6.20 on an x86_64 machine. I'm adding my route thusly:
ip route add table 100 default \
nexthop via 1.1.1.1 nexthop via 1.1.1.9
It shows correctly up in the routing table:
[EMAIL PROTECTED]:~# ip route show table 100
default
nexthop via 1.1.1.1 dev vlan11 weight 1
nexthop via 1.1.1.9 dev vlan12 weight 1
[...]
I'm sending traffic from a relatively busy network to this table:
[EMAIL PROTECTED]:~# ip rule
[...]
21000: from 1.1.2.128/26 lookup 100
[...]
I can verify with tcpdump that the rule works correctly and that the
route is used. However, the traffic is without exception routed via
1.1.1.9, not a single packet is sent to 1.1.1.1. If I however swap
the two nexthops while adding the route, all traffic is sent to
1.1.1.1, and nothing ends up at 1.1.1.9.
I've tried loading and unloading the multipath_{wrandom,rr,random,drr}
modules, removing and readding the route, and flushing the routing
cache. Several times and in different order. Nothing affects the
behaviour though, all of the traffic is sent to the router specified as
the second nexthop on the "ip route add" command line.
I feel I'm missing something essential here but I have no idea what.
Google only tells me about others having roughly the same problem but
never any solution. Do you have any suggestions for me? If I can make
this work I will be happy to document how and try to have that included
in the next kernel/iproute release and hopefully nobody will bother you
about it again.
Thanks for your time!
Kind regards
--
Tore Anderson
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