Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S275083AbTHGCOr (ORCPT ); Wed, 6 Aug 2003 22:14:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S275084AbTHGCOr (ORCPT ); Wed, 6 Aug 2003 22:14:47 -0400 Received: from sj-iport-3-in.cisco.com ([171.71.176.72]:2576 "EHLO sj-iport-3.cisco.com") by vger.kernel.org with ESMTP id S275083AbTHGCOn (ORCPT ); Wed, 6 Aug 2003 22:14:43 -0400 Message-Id: <5.1.0.14.2.20030807121131.03f21e90@mira-sjcm-3.cisco.com> X-Mailer: QUALCOMM Windows Eudora Version 5.1 Date: Thu, 07 Aug 2003 12:14:34 +1000 To: Andy Isaacson From: Lincoln Dale Subject: Re: TOE brain dump Cc: Chris Friesen , linux-kernel@vger.kernel.org In-Reply-To: <20030806120145.A15543@hexapodia.org> References: <3F312C65.9000201@nortelnetworks.com> <3F2C0C44.6020002@pobox.com> <20030802184901.G5798@almesberger.net> <20030804162433.L5798@almesberger.net> <20030806021304.E5798@almesberger.net> <20030806103758.H5798@almesberger.net> <20030806105830.B26920@hexapodia.org> <3F312C65.9000201@nortelnetworks.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1185 Lines: 31 At 03:01 AM 7/08/2003, Andy Isaacson wrote: > > > Just to be clear, I am asking for an example of a Gigabit Ethernet > > > switch that supports cut-through switching. I contend that there is no > > > such beast commercially available today. i concur. "cut-through" is generally marketing these days. there are some switches in the marketplace today which do cut-through switching, but fall back to store-&-forward when: - there is congestion in a port (i.e. output port is busy; queue frame) - the sender & receiver are of mismatched speeds - the receiver initiates gig-e flowcontrol note that "cut-through switching" means that you lose the ability of the switch to drop corrupted frames. i.e. how can it check the ethernet crc32 and validate it until its all been sent? in short, it cannot. in real-world traffic scenarios, there is very little real-world scenarios where cut-through actually occurs. cheers, lincoln. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/