From owner-freebsd-arch@FreeBSD.ORG Mon Nov 7 23:18:16 2005 Return-Path: X-Original-To: arch@freebsd.org Delivered-To: freebsd-arch@FreeBSD.ORG Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id E3FA816A421 for ; Mon, 7 Nov 2005 23:18:16 +0000 (GMT) (envelope-from cswiger@mac.com) Received: from pi.codefab.com (pi.codefab.com [199.103.21.227]) by mx1.FreeBSD.org (Postfix) with ESMTP id 7313143DA3 for ; Mon, 7 Nov 2005 23:17:53 +0000 (GMT) (envelope-from cswiger@mac.com) Received: from localhost (localhost [127.0.0.1]) by pi.codefab.com (Postfix) with ESMTP id 0C3135F8B; Mon, 7 Nov 2005 18:17:53 -0500 (EST) Received: from pi.codefab.com ([127.0.0.1]) by localhost (pi.codefab.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 32906-08; Mon, 7 Nov 2005 18:17:52 -0500 (EST) Received: from [199.103.21.238] (pan.codefab.com [199.103.21.238]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (No client certificate requested) by pi.codefab.com (Postfix) with ESMTP id 21B5B5D40; Mon, 7 Nov 2005 18:17:52 -0500 (EST) In-Reply-To: <20051107224338.GE775@funkthat.com> References: <20051107140451.GU91530@cell.sick.ru> <436F7DDB.40703@mac.com> <20051107224338.GE775@funkthat.com> Mime-Version: 1.0 (Apple Message framework v746.2) Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Message-Id: Content-Transfer-Encoding: 7bit From: Charles Swiger Date: Mon, 7 Nov 2005 18:17:51 -0500 To: John-Mark Gurney X-Mailer: Apple Mail (2.746.2) X-Virus-Scanned: amavisd-new at codefab.com Cc: arch@freebsd.org, Garance A Drosihn Subject: Re: ARP request retransmitting X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 07 Nov 2005 23:18:17 -0000 On Nov 7, 2005, at 5:43 PM, John-Mark Gurney wrote: >> While that "other hand" is true, here at RPI we deal with some of >> those other-hand issues by simply turning them off. We turn off >> multi-cast by default on some of our networks, for instance. But >> there's no way we can turn off ARP, so I think more care needs to >> be taken to make sure ARP remains network-friendly. > > And most places that have VERY large number of hosts in a broadcast > domain (a partially populated class b), have smart switches that cache > arp requests, and prevent the arp traffic from killing the network... Really? You're saying that "tcpdump -nt arp" never shows any requests except those made by the local host? Which vendor and which switch model? Smart switches will generally keep track of 1000 or 4000 or so MAC addresses and the ports those MACs are associated with, but I am not aware of anything in them which blocks ARP traffic or anything else which uses the all-ones broadcast MAC address. I can see ARP requests going out from any/all of the other machines on the network I'm using right now (using several 3com SuperStack 3300's), and I've seen the same thing on networks using the HP Procurve or Cisco 29xx switches. -- -Chuck