Le 24/06/2013 03:40, David Miller a écrit :

From: Nicolas Dichtel <redacted>
Date: Fri, 14 Jun 2013 10:32:58 +0200

quoted

There is no reason to skip ECMP lookup when oif is specified, but this implies
to check oif given by user when selecting another route.
When the new route does not match oif requirement, we simply keep the initial
one.

Spotted-by: dingzhi [off-list ref]
Signed-off-by: Nicolas Dichtel <redacted>

IPV4 routing has elided the multipath lookup when the interface is specified
for nearly two decades.

So two things:

1) A decision that old must have a good reason, and you must do some
    research to figure out exactly what that reason is.

2) If ipv4 is found to be wrong too, we must bring both ipv4 and ipv6
    into the same behavior at the same time.

In fact, routing engines are different in forwarding case:

IPv4 case:
fl4->flowi4_oif is 0 when a packet is forwarded and this value is checked to 
select or not multipath functions.

IPv6 case:
The check is done against the argument oif (not fl6->flowi6_oif) of the function 
ip6_pol_route(). And this argument is set to the input interface by 
ip6_pol_route_input().

Functions call:
   - ip6_rcv_finish() -> ip6_route_input() -> ip6_route_input_lookup() -> 
fib6_rule_lookup() -> ip6_pol_route_input() -> ip6_pol_route()

Will you accept the patch if I remove only the check of oif argument in 
ip6_pol_route() (and leave ip6_pol_route_lookup() untouched).

My goal was only to have ECMP working in the forwarding case.