Messages in this thread | | | Date | Sat, 27 Feb 1999 23:32:23 -0800 (PST) | From | "B. James Phillippe" <> | Subject | Re: ppp mru/mtu and ip masquerading |
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On Sat, 27 Feb 1999, Fuzzy Fox wrote:
> This has been a problem since the 2.0 days, with anyone using IP Masq. > There seems to be an interaction problem when the masq box has a smaller > MTU than the firewalled system, and Path MTU Discovery breaks down. At > some point, the ICMP messages necessary to support it are not being > passed along correctly. Unfortunately, no one seems to have a clear > handle no the nature of the problem. Setting the PPP MTU to be the same > as the ethernet MTU (1500) cures the problem in all cases, but many > people dislike the performance ramifications this has.
I concur. This ailed me since 2.0, on both intel and Alpha. A buddy of mine ran into it recently when he started using masq on 2.0 and I told him to try changing the MTU on his ppp to 1500, which solved the problem (as I figured it would).
David Miller asked me for some tcpdumps when I first reported it on linux-kernel over a year ago, which I sent, but he was unable to find the source of the problem. Toggling ip_no_pmtu_disc has no effect. Sort of embarrassing that Linux networking has held this bug for so long.
cheers, -bp -- B. James Phillippe . bryan@terran.org Software Engineer, WGT Inc. . http://www.terran.org/~bryan
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