When PC2 pings PC1, then several things happen:
the icmp request reaches PC1
PC1 sends icmp reply to its default gateway Router 1
Router 1 receives the reply, but doesn't forward it to Router 2, the reply gets lost somehow (can't see it anywhere in any log)
PC2 ping times out
If on PC1 I manually do route add 192.168.131.0/24 via 192.168.0.2 dev eth0 then all is fine, but this solution is not applicable in our case.
When Router 1 was SLES10sp2 all was fine. Since we updated Router 1 to SLES11sp1, we've got the above issue. I suspect some parameter changed for the kernel, but I can't find which one it is. Is there something wrong with this setup?