Date: Wed, 18 Sep 1996 22:47:11 -0700 (PDT) From: Julian Elischer <julian@current1.whistle.com> To: David Greenman <dg@Root.COM> Cc: questions@freebsd.org Subject: Re: Giant Sized Ethernet Packets Message-ID: <Pine.BSF.3.95.960918224427.3098C-100000@current1.whistle.com> In-Reply-To: <199609190350.UAA01225@root.com>
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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 >
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