From owner-freebsd-net@FreeBSD.ORG Fri Oct 19 22:35:15 2007 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 3FE0216A421 for ; Fri, 19 Oct 2007 22:35:15 +0000 (UTC) (envelope-from netslists@gmail.com) Received: from ug-out-1314.google.com (ug-out-1314.google.com [66.249.92.173]) by mx1.freebsd.org (Postfix) with ESMTP id 9A55B13C46B for ; Fri, 19 Oct 2007 22:35:12 +0000 (UTC) (envelope-from netslists@gmail.com) Received: by ug-out-1314.google.com with SMTP id y2so854279uge for ; Fri, 19 Oct 2007 15:35:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:user-agent:mime-version:to:cc:subject:references:in-reply-to:content-type:content-transfer-encoding; bh=5LEWMyoag7dBduDxmFdlVg7J39uUaHWzoR1Fxv/3H4M=; b=E8mJS+CfyvJqFy2dHoh1yse+QMwS1gWZjy5RytROR+6hVVfFRGfMn3AoUhwTXoCIxQ4MUDp6tB6cvg4sZ3mZBHFoJursfykCglWeBivvlOJxr0/YY7PedDke6+ij480eR3FpylqOhZLzSUeT8iHr2l9Dz9kGI5k4SzEjzzhX0EY= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:user-agent:mime-version:to:cc:subject:references:in-reply-to:content-type:content-transfer-encoding; b=pRo59PcHV8djMuXelEeMgdgdzJweEBYRLGJA92kPZmUM6GLLOzUy6qGEIgV/z4ZNWdlP+X496/REcH9BP2jJh8AKoJFS5qDcE8jUdxMshBVUfq/crHMH1Ug7U+pArmekMzG1wpZSs5j+0WJ7EN93W/UAvyrVsmBBDLJP0kw3W0w= Received: by 10.78.181.13 with SMTP id d13mr1771032huf.1192833305390; Fri, 19 Oct 2007 15:35:05 -0700 (PDT) Received: from ?192.168.9.8? ( [91.135.49.10]) by mx.google.com with ESMTPS id f8sm3188360nfh.2007.10.19.15.35.04 (version=SSLv3 cipher=RC4-MD5); Fri, 19 Oct 2007 15:35:04 -0700 (PDT) Message-ID: <47193112.4030701@gmail.com> Date: Sat, 20 Oct 2007 00:34:58 +0200 From: Sten Daniel Soersdal User-Agent: Thunderbird 2.0.0.6 (Windows/20070728) MIME-Version: 1.0 To: Len Gross References: <27cb3ada0710172051t536a4d11pfdfdb079ebd98932@mail.gmail.com> <20071018082056.GW39759@funkthat.com> <27cb3ada0710181842x4d214d31ob4f474ff790355b8@mail.gmail.com> In-Reply-To: <27cb3ada0710181842x4d214d31ob4f474ff790355b8@mail.gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: freebsd-net@freebsd.org, John-Mark Gurney Subject: Re: Disable Exponential Backoff (retry) on Ethernet? X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 19 Oct 2007 22:35:15 -0000 Len Gross wrote: > Thanks so much for the response. Here is some additional information. > > I'm trying to emulate an RF network where there are colisions (e.g. "Aloha" > type protocol) so I actually need collisions! I had forgotten that modern > hardware > essentially eliminated them. So, lets say I can find/use an "old hub", > can I control the number of retries? Maybe I have to find some old NICs and > old drivers? That would be very NIC specific. Retries are done in NIC hardware as far as i know. All you need to do to get some collisions is to set the rates to half-duplex on both sides (hubs were half-duplex). Hubs with lot's of traffic between other hosts would definitely produce more collisions. Modern hardware didn't eliminate them. Full-Duplex medium did. There is a broad range of full-duplex RF systems too :) -- Sten Daniel Soersdal