From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: VLAN and ARP failure on tg3 drivers Date: Mon, 26 Oct 2009 09:54:31 +0100 Message-ID: <4AE563C7.5070702@gmail.com> References: <477963.52849.qm@web32605.mail.mud.yahoo.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Gertjan Hofman , Matt Carlson , "netdev@vger.kernel.org" To: Benny Amorsen Return-path: Received: from gw1.cosmosbay.com ([212.99.114.194]:48850 "EHLO gw1.cosmosbay.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755256AbZJZIye (ORCPT ); Mon, 26 Oct 2009 04:54:34 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: Benny Amorsen a =C3=A9crit : > Gertjan Hofman writes: >=20 >> Dear Matt, Eric, Benny, >> >> Sorry about the slow response to your fast replies. I think Benny is >> correct, the 'problem' lies in the fact that we were using a VLAN ID >> of 0, without knowing its special significance. User error. >> >> I tested it with other VLAN id's (>0) and it appears to work fine. W= e >> are not entirely sure we understand why it used to work with VLAN I= D >> 0 on the Broadcom chips and still does with a number of different >> cards (with >2.6.27 kernels). What is the 'correct' behaviour for >> this incorrect usage ? >=20 > VLAN 0 isn't incorrect, it's just surprising. When you send a packet > tagged with VLAN 0, it means that the packet should be interpreted as > being the same VLAN as a completely untagged packet. >=20 > So in theory, if both ends are using VLAN 0 and you aren't using eth0 > for anything, traffic should flow, at least if both ends are on the s= ame > kernel version. Feel free to debug why that isn't the case for you, o= f > course... >=20 VLAN id 0 is not usable on current kernel because we use 16 bits in skb= to store vlan_tci, and vlan_tci =3D 0 means there is no VLAN tagging. We could use high order bit (0x8000) to tell if vlan tagging is set or = not.