From owner-freebsd-questions Wed Sep 18 22:50:07 1996 Return-Path: owner-questions Received: (from root@localhost) by freefall.freebsd.org (8.7.5/8.7.3) id WAA29664 for questions-outgoing; Wed, 18 Sep 1996 22:50:07 -0700 (PDT) Received: from whistle.com (s205m131.whistle.com [207.76.205.131]) by freefall.freebsd.org (8.7.5/8.7.3) with ESMTP id WAA29625 for ; Wed, 18 Sep 1996 22:50:02 -0700 (PDT) Received: (from smap@localhost) by whistle.com (8.7.5/8.6.12) id WAA11858; Wed, 18 Sep 1996 22:49:00 -0700 (PDT) Received: from current1.whistle.com(207.76.205.22) by whistle.com via smap (V1.3) id sma011856; Wed Sep 18 22:48:44 1996 Date: Wed, 18 Sep 1996 22:47:11 -0700 (PDT) From: Julian Elischer To: David Greenman cc: questions@freebsd.org Subject: Re: Giant Sized Ethernet Packets In-Reply-To: <199609190350.UAA01225@root.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII 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 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.. > > >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 >