From mboxrd@z Thu Jan 1 00:00:00 1970 From: Martin Casado Subject: Re: [ovs-dev] [GIT PULL v2] Open vSwitch Date: Mon, 28 Nov 2011 07:50:36 -0800 Message-ID: <4ED3ADCC.604@nicira.com> References: <20111123075433.GA7928@gondor.apana.org.au> <1322050976.2039.125.camel@mojatatu> <20111128130409.GB16828@gondor.apana.org.au> <1322488954.7338.66.camel@mojatatu> <4ED3A85A.1030003@nicira.com> <1322494356.7338.75.camel@mojatatu> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Herbert Xu , dev@openvswitch.org, netdev@vger.kernel.org, David Miller To: Jamal Hadi Salim Return-path: Received: from smtp-roam1.Stanford.EDU ([171.67.219.88]:60173 "EHLO smtp-roam.stanford.edu" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753228Ab1K1Puk (ORCPT ); Mon, 28 Nov 2011 10:50:40 -0500 In-Reply-To: <1322494356.7338.75.camel@mojatatu> Sender: netdev-owner@vger.kernel.org List-ID: >> This is a common misunderstanding about OpenFlow. It does not require >> the first packet of each flow to go to the controller. > I am reading this to mean that the switch CPU will resolve things? > Typically those tend to be tiny cpus. > No, no datapath traffic leaves the switching chip. Generally controllers calculate full forwarding tables using wildcarded rules and use low priority rules to handle exception traffic (still keeping it on the datapath). > >> In fact, no >> production system I'm aware of does this. Generally OpenFlow-based >> solutions targeted at large environments (e.g. data center, or WAN) >> send only traditional control traffic to the controller (e.g. BGP or >> OSPF), or none at all. > Even OSPF or BGP would be problematic imo if the architecture doesnt > allow prioritization of some form towards the controller. Indeed. Controllers generally implement such prioritization by using OpenFlow forwarding rules that match on control traffic and explicitly set the controller as the destination. This allows the application of any QoS primitives within OpenFlow to control traffic. best, .martin > > cheers, > jamal > > -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~ Martin Casado Nicira Networks, Inc. www.nicira.com cell: 650-776-1457 ~~~~~~~~~~~~~~~~~~~~~~~~~~~