Date: Mon, 19 Mar 2007 17:21:56 -0700 From: Kevin Lahey <kml@patheticgeek.net> To: freebsd-net@freebsd.org Subject: Re: PMTU Discovery support Message-ID: <20070319172156.68cba0a9@yakko.patheticgeek.net> In-Reply-To: <20070319145422.39bfddcd@yakko.patheticgeek.net> References: <994cd1cf0703050842r5e54daa6y5fe6af3083e15cd@mail.gmail.com> <45EC6E88.3080101@tomjudge.com> <20070305115615.W38684@orthanc.ca> <994cd1cf0703052105y375679a4t482f4e35988f9daf@mail.gmail.com> <20070319145422.39bfddcd@yakko.patheticgeek.net>
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On Mon, 19 Mar 2007 14:54:22 -0700 Kevin Lahey <kml@patheticgeek.net> wrote: > Of course, the real test is to set up a few hosts and see what > happens, rather than speculating based on a quick perusal of the > code. :-) After my slap-dash read of the current FreeBSD code, I was a little concerned that I'd missed something. As penance, I set up a quick experiment with four hosts connected in a line, A <-> B <-> C <-> D, set the MTU on the links from B to C to 512, and ran ttcp from A to D. PMTUD worked correctly. Then I suspended the ttcp process, went away for an hour, and resumed it. Watching tcpdump, it appears that 512 octet packets continued to be sent, with no attempt at probing. That would seem to be a bug. The boxes were running FreeBSD-6.1, but I can't really vouch for the particular kernel configuration. It could well be that the problem is with the loose nut behind the wheel, rather than with FreeBSD. :-) Kevin kml@patheticgeek.net
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