Date: Thu, 8 Jun 2000 00:13:17 -0600 From: "Kenneth D. Merry" <ken@kdm.org> To: Dave Preece <dave.preece@kbgroup.co.nz> Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: Path MTU discovery. Message-ID: <20000608001317.A62030@panzer.kdm.org> In-Reply-To: <67B808B0DD93D211ABEE0000B498356B02BC70@internet.kbgroup.co.nz>; from dave.preece@kbgroup.co.nz on Thu, Jun 08, 2000 at 06:03:45PM %2B1200 References: <67B808B0DD93D211ABEE0000B498356B02BC70@internet.kbgroup.co.nz>
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On Thu, Jun 08, 2000 at 18:03:45 +1200, Dave Preece wrote: > Just learning about this: I can see the advantages but does anything use it? Sure, TCP uses it. TCP (at least in FreeBSD) sets the "don't frag" bit on all its outgoing packets. If the packet gets to a router with an outgoing MTU that is too small to hold the packet without fragmentation, the router is supposed to send back and ICMP message telling the source machine to use a smaller packet size. When the source machine receives the ICMP message, it will update the MTU for that route, and try sending packets out again with the lower MTU. Ken -- Kenneth Merry ken@kdm.org To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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