From owner-freebsd-hackers Fri Mar 1 3:56:33 2002 Delivered-To: freebsd-hackers@freebsd.org Received: from iguana.icir.org (iguana.icir.org [192.150.187.36]) by hub.freebsd.org (Postfix) with ESMTP id 8978737B417 for ; Fri, 1 Mar 2002 03:56:29 -0800 (PST) Received: (from rizzo@localhost) by iguana.icir.org (8.11.6/8.11.3) id g21BuN233060; Fri, 1 Mar 2002 03:56:23 -0800 (PST) (envelope-from rizzo) Date: Fri, 1 Mar 2002 03:56:23 -0800 From: Luigi Rizzo To: Bob Bishop Cc: "George V. Neville-Neil" , Doug Ambrisko , hackers@FreeBSD.ORG Subject: Re: Multicast problem with sis interface? Message-ID: <20020301035623.A32974@iguana.icir.org> References: <200203010557.VAA1802420@meer.meer.net> <4.3.2.7.2.20020222165515.00c14850@gid.co.uk> <200203010557.VAA1802420@meer.meer.net> <4.3.2.7.2.20020301112956.00c5b550@gid.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4.3.2.7.2.20020301112956.00c5b550@gid.co.uk> User-Agent: Mutt/1.3.23i Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On Fri, Mar 01, 2002 at 11:37:03AM +0000, Bob Bishop wrote: > Hi, > > At 01:10 01/03/02 -0800, Luigi Rizzo wrote: > >I do not agree with the explaination. Padding is padding, the actual > >value is irrelevant. Plus, in the tcpdump below, the are actually > >46 bytes of data, which together with the 14 of the MAC header and > >the 4bytes of CRC make a perfectly legal packet. > > Correct, but the trailing 1's were supplied by the switch between the box > with the sis and the box running tcpdump. I find this hard to believe. The "sis" driver does the padding itself, using ones for the padding. I have verified this locally. And a switch which receives a short packet (runt packet) is not supposed to pass it through. > >What kind of protocol are we talking about ? > > Appletalk NBP, for instance. can you try and instruments the calls in the protocol stack which are issued to generate the packet ? > >Which are the other drivers that "work" ? > > ed, vr, rl ok, these three drivers behave as follows: "ed" pads with whatever is left in the transmit buffer from earlier transmissions; "vr" pads with whatever is available in the mbuf after the actual data; "rl" pads with zeroes (in the driver) and of course "sis" pads in hardware (with ones) The beauty of diversity... cheers luigi To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message