Date: Mon, 7 Dec 1998 18:43:12 +0200 From: Ruslan Ermilov <ru@ucb.crimea.ua> To: Thomas David Rivers <rivers@dignus.com> Cc: hackers@FreeBSD.ORG Subject: Re: TCP bug Message-ID: <19981207184312.A7011@ucb.crimea.ua> In-Reply-To: <199812071611.LAA01157@lakes.dignus.com>; from Thomas David Rivers on Mon, Dec 07, 1998 at 11:11:16AM -0500 References: <19981207175804.A1183@ucb.crimea.ua> <199812071611.LAA01157@lakes.dignus.com>
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On Mon, Dec 07, 1998 at 11:11:16AM -0500, Thomas David Rivers wrote: > > Umm. Have you tried to disable PMTU on your FreeBSD box? > > > > Nope.. do you mean on the interior nodes or the gateway - or both? > (Some of my interior nodes aren't FreeBSD... so I may not have that option.) > I mean the FreeBSD box you are sitting on and from which you can't access www.aol.com. > And, I thought I would find something about that in the sysctls - say, > net.inet.XXX - but nothing jumps out at me... which sysctl would disable > MTU-D? MTU can be disabled on per-route basis. It is neither clear, nor documented. This can be done by locking MTU on a route. For example, if you want to disable PMTU-D on default, you should say: # route change default -lock -mtu 1500 (or whatever you have it set to) ! Note, that if you specify -mtu without parameter (this is what came to my ! mind first), route command will coredump. Now, you should be able to check that PMTU-D is disabled by: a) ``route get default'' will show mtu as 1500L, i.e. 1500 and locked; b) ``route get www.aol.com'' will show the same mtu, because this route is cloned from the default (or maybe you have direct route to AOL?); c) ``tcpdump'' won't show DF bit in outgoing packets (this is for sure). BR, -- Ruslan Ermilov Sysadmin and DBA of the ru@ucb.crimea.ua United Commercial Bank +380.652.247.647 Simferopol, Ukraine http://www.FreeBSD.org The Power To Serve http://www.oracle.com Enabling The Information Age To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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