Route being asymmetrically ignored

  • Hi, all! I kept struggling with my routing problem, sniffed every packet I could and managed to produce a very detailed description of what I am dealing with, but remain clueless. I attach the nice picture that's worth a thousand words.

    Notice that A, B, and C are pfSense 1.2.2 boxes and all happens consistently as in the picture. B and C have the right routes, which are used in both ICMP requests. However, the very same routes are ignored in both ICMP replies, which are necessarily directed to A, the default route. What's more, if A is down no such pings ever complete, which means that those nice routes are never considered for ICMP replies. That's why I say "asymmetrically ignored" for AFAIK routers and the IP protocol should not care whether they are carrying ICMP replies or requests. TCP and other protocols are affected likewise.

    Thanks in advance for any pointers on a matter that has been keeping me busy for days now. Cheers,


  • Nobody has ever heard of something like this? Any ideas where I can find help on this problem?

    Thanks in advance. Cheers,


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