From mboxrd@z Thu Jan 1 00:00:00 1970 From: jamal Subject: Re: change the way e1000 is handling short VLAN frames Date: Fri, 21 Sep 2007 09:37:21 -0400 Message-ID: <1190381841.4231.10.camel@localhost> References: <1190359905.3551.28.camel@magi.nadr> <1190375946.4261.42.camel@localhost> <1190379015.3551.57.camel@magi.nadr> Reply-To: hadi@cyberus.ca Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: "auke-jan.h.kok@intel.com" , netdev mailing list , Ben Greear To: Emil Micek Return-path: Received: from an-out-0708.google.com ([209.85.132.241]:33381 "EHLO an-out-0708.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759601AbXIUNh0 (ORCPT ); Fri, 21 Sep 2007 09:37:26 -0400 Received: by an-out-0708.google.com with SMTP id d31so130184and for ; Fri, 21 Sep 2007 06:37:26 -0700 (PDT) In-Reply-To: <1190379015.3551.57.camel@magi.nadr> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Fri, 2007-21-09 at 14:50 +0200, Emil Micek wrote: > On Fri, 2007-09-21 at 07:59 -0400, jamal wrote: > > Which would make it a bug. AFAIK, the minimum VLAN tagged packet going > > out is 68 bytes. > Are you sure about this? This is what i have always seen. Double checked with google and she gave me many a url, example: http://www.cisco.com/warp/public/473/741_4.html I think you can pretty much trust cisco on something as basic as this. Also: http://www.techfest.com/networking/lan/ethernet2.htm > We did some extensive testing capturing VLAN > frames going out of our Intel PRO/1000 MT Dual Port Server Adapter > (82571EB chipset) and we definitely captured VLAN frames shorter then 68 > bytes. Here is text dump of such frame: > http://www.tkrjasek.cz/mie/cmts_tests/between_linux_and_cmts.txt Do you have access to another NIC? a tg3 based one will be good to test for hardware level tagging. > (note that wireshark captures the frames without 4 bytes FCS (frame > check sequence) so the above packet is in fact 66 bytes long). > > What is the right behaviour according to specification? In iee802.3, > minFrameSize is 64bytes. I've never seen any document which'd say that > VLAN frames should be 68 bytes minimum. Refer to above. > Now i'm little confused by your reply, becaouse you write, that VLAN > frames generated by e1000 should be 68 bytes minimum, which contradicts > witch our observations. Miscommunication ;-> I said the packets going out should be 68B otherwise it is a bug. if e1000 is sending 64B out, it is a bug. I think any other NIC that doesnt do hardware based vlan tags would be good to try as well because it uses the software stack to do the tagging. cheers, jamal