From owner-freebsd-hackers Thu Oct 23 10:05:20 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.7/8.8.7) id KAA10706 for hackers-outgoing; Thu, 23 Oct 1997 10:05:20 -0700 (PDT) (envelope-from owner-freebsd-hackers) Received: from mole.mole.org (marmot.mole.org [204.216.57.191]) by hub.freebsd.org (8.8.7/8.8.7) with SMTP id KAA10691 for ; Thu, 23 Oct 1997 10:05:14 -0700 (PDT) (envelope-from mrm@mole.mole.org) Received: (from mail@localhost) by mole.mole.org (8.6.12/8.6.12) id RAA23067; Thu, 23 Oct 1997 17:04:27 GMT Received: from meerkat.mole.org(206.197.192.20) by mole.mole.org via smap (V1.3) id sma023065; Thu Oct 23 17:04:02 1997 Received: (from mrm@localhost) by meerkat.mole.org (8.6.11/8.6.9) id KAA06454; Thu, 23 Oct 1997 10:02:06 -0700 Date: Thu, 23 Oct 1997 10:02:06 -0700 From: "M.R.Murphy" Message-Id: <199710231702.KAA06454@meerkat.mole.org> To: darrenr@cyber.com.au Subject: Re: MTU Path discovery. Cc: freebsd-hackers@freebsd.org Sender: owner-freebsd-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk > > I'm want to add a sysctl knob to control this (default to on). > > At present, MTU path discovery only seems to be enabled for TCP, but > I'm reluctant to make it "net.inet.tcp.mtupathdiscovery" as I don't > want to limit its scope. However, I'm open for comments about > whether it should be ip or icmp. > > I don't think the current behaviour (is on and cannot be controlled) > is all that desirable. > >From experience: MTU path discovery isn't that all fired reliable. Better to just set the MTU to the highest guaranteed value on the last outgoing router under one's control and leave it at that. I can't remember if it's 296. I hate losing my memory :-( The number is in the RFC's. Better to take the performance hit than not have a reliable connection. The hitch is blackhole routers. -- Mike Murphy mrm@Mole.ORG +1 619 598 5874 Better is the enemy of Good