On 2012-06-12 14:08, Bernd wrote:
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.
Without having the details of your setup, the big principle is: pf is
stateful (by default). Statefulness doesn't play well with asymmetric
routing. I'm sure if you investigate a little bit more you'll discover
it's not limited to ICMP.
In the end the solution will be one of: remove statefulness, avoid
asymmetric routing, or share state with pfsync.
My two cents: try to avoid statefulness on core routers. Move stateful
elements to the edge, where routing is symmetric.
Simon
