From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tom Brown Subject: Use of 802.3ad bonding for increasing link throughput Date: Wed, 10 Aug 2011 13:07:53 +0100 Message-ID: <4E427499.8060108@cyconix.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit To: netdev Return-path: Received: from queue02.mail.zen.net.uk ([212.23.3.27]:37231 "EHLO queue02.mail.zen.net.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750800Ab1HJNSF (ORCPT ); Wed, 10 Aug 2011 09:18:05 -0400 Received: from [212.23.3.142] (helo=smarthost03.mail.zen.net.uk) by queue02.mail.zen.net.uk with esmtp (Exim 4.72) (envelope-from ) id 1Qr7Zw-0006IN-JL for netdev@vger.kernel.org; Wed, 10 Aug 2011 12:08:08 +0000 Received: from 82-70-243-134.dsl.in-addr.zen.co.uk ([82.70.243.134] helo=[127.0.0.1]) by smarthost03.mail.zen.net.uk with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.63) (envelope-from ) id 1Qr7Zp-0001YZ-FD for netdev@vger.kernel.org; Wed, 10 Aug 2011 12:08:01 +0000 Sender: netdev-owner@vger.kernel.org List-ID: [couldn't thread with '802.3ad bonding brain damaged', as I've just signed up] So, under what circumstances would a user actually use 802.3ad mode to "increase" link throughput, rather than just for redundancy? Are there any circumstances in which a single file, for example, could be transferred at multiple-NIC speed? The 3 hashing options are: - layer 2: presumably this always puts traffic on the same NIC, even in a LAG with multiple NICs? Should layer 2 ever be used? - layer2+3: can't be used for a single file, since it still hashes to the same NIC, and can't be used for load-balancing, since different IP endpoints go unintelligently to different NICs - layer3+4: seems to have exactly the same issue as layer2+3, as well as being non-compliant I guess my problem is in understanding whether the 802.3/802.1AX spec has any use at all beyond redundancy. Given the requirement to maintain frame order at the distributor, I can't immediately see how having a bonded group of, say, 3 NICs is any better than having 3 separate NICs. Have I missed something obvious? And, having said that, the redundancy features seem limited. For hot standby, when the main link fails, you have to wait for both ends to timeout, and re-negotiate via LACP, and hopefully pick up the same lower-priority NIC, and then rely on a higher layer to request retransmission of the missing frame. Do any of you have any experience of using 802.1AX for anything useful and non-trivial? So, to get multiple-NIC speed, are we stuck with balance-rr? But presumably this only works if the other end of the link is also running the bonding driver? Thanks - Tom