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To: "Gary Palmer" <gpalmer@freebsd.org>
cc: rohit@cs.UMD.EDU, freebsd-hackers@freebsd.org
From: "Louis A. Mamakos" <louie@TransSys.COM>
Subject: Re: Giant Sized Ethernet Packets 
References: <27177.843124507@orion.webspan.net> 
In-reply-to: Your message of "Thu, 19 Sep 1996 05:15:07 EDT."
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Date: Thu, 19 Sep 1996 08:50:02 -0400
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> rohit@cs.UMD.EDU wrote in message ID
> <199609190233.WAA18658@darling.cs.UMD.EDU>:
> > I was wondering if it is possible to send giant sized ethernet packets (>1500
> > bytes say 1550) using the current 'de' driver for the SMC 10/100 DEC 21140 
> > cards.
> 
> > If not, would somebody know if this is possible with the above h/w
> > at all? 
> 
> > Any pointers to other h/w over which giant packets are possible would
> > be appreciated.
> 
> You can't without violating the IEE 802.3 specs for Ethernet, from
> what I remember. To go to larger packet sizes use FDDI.

Yeah, but if you're in an environment where the links are running
full duplex and are connected to a Fast Ethernet switch, then you
don't have to worry about the collision domain not working "correctly".

Being able to support FDDI MTUs would eliminate needless fragmentation
which is very time consuming to perform in routers.   I'd love to have
FDDI (or larger!) size MTU support in Fast Ethernet VLSI.  I think that
this is likely going to be part of Gigabit ethernet as it develops, and

I think we'll eventually see something for Fast Ethernet too, based on
converstations with router vendors.  Heck, compare the cost of a small
Fast Ethernet switch (like the Bay Networks 58000) with an equivilently
sized DEC Gigaswitch.  And you can't easily find FDDI that runs full 
duplex, either.

Louis Mamakos