pf and ICMP in asymmetric routing setups

[Bernd]

Hi list,

I've got two OpenBSD 5.1-stable/amd64 boxes employed which do all the 
routing for our AS (OpenBGPd and OpenOSPFd). I see asymmetric traffic (I 
thought it to be that way), which itself doesn't really create problems. 
However, I see problems with ICMP. pf seems to drop all but the first 
response from any of the hosts within our network (seen from the 
Internet).

Any idea how to deal with this? As soon as I turn off pf, everything 
runs smoothly.

Best,

Bernd