From owner-freebsd-questions Wed Sep 18 23:08:12 1996 Return-Path: owner-questions Received: (from root@localhost) by freefall.freebsd.org (8.7.5/8.7.3) id XAA09268 for questions-outgoing; Wed, 18 Sep 1996 23:08:12 -0700 (PDT) Received: from mail.crl.com (mail.crl.com [165.113.1.22]) by freefall.freebsd.org (8.7.5/8.7.3) with SMTP id XAA09247 for ; Wed, 18 Sep 1996 23:08:09 -0700 (PDT) Received: from root.com (implode.root.com) by mail.crl.com with SMTP id AA28503 (5.65c/IDA-1.5 for ); Wed, 18 Sep 1996 23:08:43 -0700 Received: from localhost (localhost [127.0.0.1]) by root.com (8.7.5/8.6.5) with SMTP id XAA01531; Wed, 18 Sep 1996 23:07:02 -0700 (PDT) Message-Id: <199609190607.XAA01531@root.com> X-Authentication-Warning: implode.root.com: Host localhost [127.0.0.1] didn't use HELO protocol To: Julian Elischer Cc: questions@freebsd.org Subject: Re: Giant Sized Ethernet Packets In-Reply-To: Your message of "Wed, 18 Sep 1996 22:47:11 PDT." From: David Greenman Reply-To: dg@root.com Date: Wed, 18 Sep 1996 23:07:02 -0700 Sender: owner-questions@freebsd.org X-Loop: FreeBSD.org Precedence: bulk > > >On Wed, 18 Sep 1996, David Greenman wrote: > >> >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. >> >> No. >Bzzzzt! >Sorry, but thanks for playing.. >don't forget to collect your tie-pin on the way out.. >The chip it trivially programeed to do this.. we do it all teh time with Again, read the question and what I replied. The current de driver does NOT support this! >15500 byte packets.. (10 x normal) > >It's to support legacy systems that date from the dawn of ethernet when >the >packet size was not so 'fixed' as it is now.. Are you sure that this works in 100BASE-TX mode? The question was about the DC21140... >> >If not, would somebody know if this is possible with the above h/w >> >at all? >> >> The answer to this is complicated, but it basically ends up being "no". >> I just spent about 15 minutes looking over the DC21140 hardware reference >> manual. It appears that the chip can except larger frames, but it signals >> an error condition when this occurs, so I don't think you could do this >> as a normal mode of operation. It also appears that it is possible to >> generate larger than 1500 byte packets, but the frames wouldn't be ethernet >> (the type/length field would not be IEEE 802.3) and you'd have to invent your >> own encapsulation. ...that's how I read it, anyway. Perhaps Matt Thomas will >> correct me on this. -DG David Greenman Core-team/Principal Architect, The FreeBSD Project