Date: Fri, 19 Jun 1998 22:17:09 -0400 (EDT) From: spork <spork@super-g.com> To: Joel Ray Holveck <joelh@gnu.org> Cc: opsys@mail.webspan.net, root@bmccane.maxbaud.net, hackers@FreeBSD.ORG Subject: Re: TweakDUN Message-ID: <Pine.BSF.3.96.980619220851.25847A-100000@super-g.inch.com> In-Reply-To: <199806200006.TAA10769@detlev.UUCP>
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On Fri, 19 Jun 1998, Joel Ray Holveck wrote: > > Okay, I'm a bit confused here. How does the broken stack affect this > issue? I thought it was a network design issue, since (if I > understand correctly) many ISPs' uplinks use an MTU of 576, so any > system using an MTU of 1500 (which includes the FreeBSD default) is > going to have their packets broken into three packets of 576, 576, and > 348 bytes. So, to reduce overhead, the MTU is set to 576 originally > (why not 1152 I don't know) and life goes on. I can't think of anywhere this is true. I'll use our dialup pools as an example: modem-> dialup PPP 1500 -> term server -> ethernet 1500 -> router -> T1(s) HDLC 1500 -> core router -> fast ethernet 1500 -> upstream's border router -> FDDI 40?? -> upstream core router -> ATM/SONET/whatever ? Generally, one avoids small MTUs on big links, I beleive. ATM's small cell size makes *every* packet get fragmented at layer 2, but I'm not sure that's even relevant. Anyone else? I've never heard of the oft quoted "Internet standard MTU of 576"... Charles > > Am I mistaken? > > Best, > joelh > > -- > Joel Ray Holveck - joelh@gnu.org - http://www.wp.com/piquan > Fourth law of programming: > Anything that can go wrong wi > sendmail: segmentation violation - core dumped > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-hackers" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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