From owner-freebsd-arch@FreeBSD.ORG Fri Nov 11 14:09:37 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 AD24716A41F; Fri, 11 Nov 2005 14:09:37 +0000 (GMT) (envelope-from bms@spc.org) Received: from arginine.spc.org (arginine.spc.org [83.167.185.2]) by mx1.FreeBSD.org (Postfix) with ESMTP id 4647D43D69; Fri, 11 Nov 2005 14:09:37 +0000 (GMT) (envelope-from bms@spc.org) Received: from localhost (localhost [127.0.0.1]) by arginine.spc.org (Postfix) with ESMTP id 80C8C6541D; Fri, 11 Nov 2005 14:09:36 +0000 (GMT) Received: from arginine.spc.org ([127.0.0.1]) by localhost (arginine.spc.org [127.0.0.1]) (amavisd-new, port 10024) with LMTP id 10042-01-15; Fri, 11 Nov 2005 14:09:36 +0000 (GMT) Received: from empiric.dek.spc.org (unknown [62.53.14.79]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by arginine.spc.org (Postfix) with ESMTP id D90AF65410; Fri, 11 Nov 2005 14:09:35 +0000 (GMT) Received: by empiric.dek.spc.org (Postfix, from userid 1001) id AB0196B39; Fri, 11 Nov 2005 14:09:26 +0000 (GMT) Date: Fri, 11 Nov 2005 14:09:26 +0000 From: Bruce M Simpson To: Gleb Smirnoff Message-ID: <20051111140926.GC733@empiric.icir.org> References: <20051107140451.GU91530@cell.sick.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20051107140451.GU91530@cell.sick.ru> Cc: arch@FreeBSD.org 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: Fri, 11 Nov 2005 14:09:37 -0000 On Mon, Nov 07, 2005 at 05:04:51PM +0300, Gleb Smirnoff wrote: > I suggest to keep sending ARP requests while there is a demand for > this (we are trying to transmit packets to this particular IP), > ratelimiting these requests to one per second. This will help in a > quite common case, when some host on net is rebooting, and we are > waiting for him to come up, and notice this only after 1 - 20 seconds > since the time it is reachable. > Any objections? In response to the other replies to this thread citing broadcast pollution on Ethernet-based networks: Please add this functionality under a sysctl where it is turned off by default. It is desirable in situations where ARP entries cached further upstream are stale, but it may cause flooding in an environment where the layer 2 backbone hasn't been split or has not been segregated well. Other people cited examples where vendor switch implementations were retransmitting across VLANs -- this week I've been offering moral support to a friend who is dealing with similar VLAN brokenness at his $DAYJOB (there was an extension to 802.1d to support multiple spanning tree instances across VLANs which I think not everyone supports correctly). Regards, BMS