From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Smith Subject: Re: [net-next-2.6 PATCH] net: fast consecutive name allocation Date: Sun, 15 Nov 2009 09:06:04 +1030 Message-ID: <20091115090604.331d75c2@opy.nosense.org> References: <20091113233504.GQ19478@kvack.org> <20091113153924.6130135f@nehalam> <20091113235210.GR19478@kvack.org> <20091113.185937.251557071.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: bcrl@lhnet.ca, shemminger@vyatta.com, opurdila@ixiacom.com, eric.dumazet@gmail.com, netdev@vger.kernel.org To: David Miller Return-path: Received: from smtp4.adam.net.au ([202.136.110.247]:43186 "EHLO smtp4.adam.net.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751109AbZKNWgM (ORCPT ); Sat, 14 Nov 2009 17:36:12 -0500 In-Reply-To: <20091113.185937.251557071.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On Fri, 13 Nov 2009 18:59:37 -0800 (PST) David Miller wrote: > From: Benjamin LaHaise > Date: Fri, 13 Nov 2009 18:52:10 -0500 > > > If you don't want the overhead from this kind of scaling, stick it under a > > config option, but please don't stop other people from pushing Linux into > > new uses which have these scaling requirements. > > This 'scaling requirement' only exists in environments where people > undersubsribe their networks, right? > > I'm not saying we won't put scaling into these areas, I'm just trying > to make a point to show that this "need" only exists because people > have purposefully created these situations where they feel the need to > massively control their users usage in order to generate revenue. I'm don't understand that comment, and I work for (and designed most of the infrastructure for) an ISP that usually has well over 40 000 concurrent PPPoE sesssions at any one time. The fundamental purpose of PPPoE is nothing to do with any scaling or architecture, it is purely to make a more modern shared networking technology like Ethernet look like high speed dial up. This has occurred mainly because when broadband came along it allowed ISPs to introduce it quickly, without having to also upgrade their dial up oriented backend systems i.e. customer authentication/accounting and customer support systems. It wasn't ideal then and it isn't ideal now. PPPoE adds an overhead of 8 bytes per packet, yet the only thing it is doing is changing ethernet from multipoint to point-to-point so PPP can run over it and providing ISPs with an ability to identify the subscriber. There are other methods to solve customer identity problem without the PPPoE overheads. Moving to them however can be a long drawn out process because it also means changes to customer's CPE settings, or running the old and new methods in parallel for the foreseeable future. On the occasions I've looked at whether a Linux box would be an alternative to the Cisco BRAS platform we use, the last time I looked the number of sessions people were saying they were running was 500. I don't consider Linux to be feasible in that role until you're able to run at least 5000 sessions on a single box. I'm a bit unusual in that regard, as I prefer the "lots of smaller, increase chances of failure, but consequences of failure" model - you manage the larger number of them via configuration templating / scripted change deployment. You need to chose your subscriber per device level, and if 500 is the current limit for Linux, then in my opinion it is currently too low for my application. Others in the industry might consider 5000 too low, as they are running devices that can handle 32 000 or 64 000 PPPoE sessions. > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html