From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Philip A. Prindeville" Subject: Re: [PATCH] ipv4: add DiffServ priority based routing Date: Thu, 11 Mar 2010 12:25:24 -0700 Message-ID: <4B9943A4.8040606@redfish-solutions.com> References: <201001121432.43301.schmto@hrz.tu-chemnitz.de> <20100112.121607.39835310.davem@davemloft.net> <4B4CE2B8.1040702@redfish-solutions.com> <20100112.130355.144803575.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: torsten.schmidt@s2006.tu-chemnitz.de, netdev@vger.kernel.org To: David Miller Return-path: Received: from mail.redfish-solutions.com ([66.232.79.143]:32888 "EHLO mail.redfish-solutions.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756338Ab0CKTZb (ORCPT ); Thu, 11 Mar 2010 14:25:31 -0500 In-Reply-To: <20100112.130355.144803575.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On 01/12/2010 02:03 PM, David Miller wrote: > From: "Philip A. Prindeville" > Date: Tue, 12 Jan 2010 12:59:36 -0800 > >> What has changed is how network equipment is required to interpret >> the meaning of those bits. >> >> Even if we pass the bits "as is" to the network, if the network is >> applying entirely new semantics (and when I say "entirely new", I >> mean those mandated since 1998), then compatibility in the host >> kernel API doesn't matter a hoot since the packets will still be >> handled by every transited router according to the modern semantics. > > People really don't assign global meaning to bits set by applications > in the TOS field. > > What they do is they have a set of semantics inside of their cloud of > routers and switch points for diffserv, and when packets come in the > TOS field is rewritten to whatever scheme is being used inside of that > cloud. > > And the diffserv bits only have meaning and effect within that cloud. > > So really, having a syscall that sets the TOS bits exactly by > applications is just fine. > > People are doing diffserv right now with Linux and have done so > for years. Sorry about coming back to this weeks later... but I hadn't seen RFC 4594 previously. What if boxes (i.e. the OS) and applications can preconfigured to use RFC-4594 guidelines by default, and varying from that required the administrator to make specific changes? I agree with the notion that certain values should be set side-wide (or at least system-wide) to prevent malicious users from exploiting QoS... that's why I've been advocating for QoS settings to be specified in a system configuration file, and not a per-user configuration file. -Philip