From owner-freebsd-stable@FreeBSD.ORG Mon Sep 19 17:31:29 2005 Return-Path: X-Original-To: freebsd-stable@freebsd.org Delivered-To: freebsd-stable@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 8545F16A41F for ; Mon, 19 Sep 2005 17:31:29 +0000 (GMT) (envelope-from Colin.Farley@ecarecenters.com) Received: from ranger.electric.net (ranger.electric.net [216.129.90.29]) by mx1.FreeBSD.org (Postfix) with ESMTP id DDFE843D46 for ; Mon, 19 Sep 2005 17:31:28 +0000 (GMT) (envelope-from Colin.Farley@ecarecenters.com) Received: from root by ranger.electric.net with emc1-ok (Exim 4.24) id 1EHPUC-0000y4-Ua for freebsd-stable@freebsd.org; Mon, 19 Sep 2005 10:31:24 -0700 Received: by emcmailer; Mon, Sep 19 2005 10:31:24 -0700 Received: from [64.4.68.42] (helo=wpg1-notesmail.PRLOANS.LAN) by ranger.electric.net with esmtp (Exim 4.24) id 1EHPU9-0000v6-UQ for freebsd-stable@freebsd.org; Mon, 19 Sep 2005 10:31:21 -0700 Importance: Normal X-Priority: 3 (Normal) From: Colin Farley To: freebsd-stable@freebsd.org Date: Mon, 19 Sep 2005 12:31:17 -0500 Message-ID: X-Mailer: Lotus Domino Web Server Release 6.5.4 March 27, 2005 X-MIMETrack: Serialize by Notes Server on WebMail/COMPUBank(Release 6.5.4|March 27, 2005) at 09/19/2005 12:31:17 PM, Serialize complete at 09/19/2005 12:31:17 PM, Itemize by Notes Server on WebMail/COMPUBank(Release 6.5.4|March 27, 2005) at 09/19/2005 12:31:17 PM, Serialize by Router on PRLUSA-NOTESMAIL/COMPUBank(Release 6.5.3|September 14, 2004) at 09/19/2005 12:31:20 PM, Serialize complete at 09/19/2005 12:31:20 PM Content-Transfer-Encoding: quoted-printable X-Virus-Status: Scanned by VirusSMART (s) MIME-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Subject: Gratuitous ARP X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 19 Sep 2005 17:31:29 -0000 Hi all, I am using UCARP on two FreeBS= D 4.10-RELEASE-p16 nodes to offer highly available apache virtual hosts.&nb= sp; Everything seems to work very well except that occasionally one webserv= er will become inaccessable from outside it's subnet. I have narrowed= this down to an arp issue. When a UCARP IP becomes unavailable. = ; I normally start a constant ping to it from my machine which lives on a d= ifferent subnet, all requests timeout. I log into the cisco router th= at has an interfaces living on the webserver's subnet. I then view th= e arp table of the cisco router an see that the MAC that is listed for that= UCARP IP is the MAC of the inactive node. I then clear the arp cache= on the cisco router, this makes the routers arp table update correctly aft= er that my ping requests get replied and the webserver is again accessible = from the outside. So, I have come up with a few = solutions to this problem, which include: 1.&nbs= p; Set the arp cache timeout of the cisco router very low so that outages a= re minimal. I would rather not do this as it will problably stress th= e router too much. Unfortunately I know little about cisco devices so= I really cant figure this one out, does anyone think that this is a bad th= ing? Can you tell a cisco device not to cache arp entries on just the= internal interface? The subnet currently consists of about 25 hosts = so this may not be so bad after all? 2. Run an ANT task to = clear the cache on the cisco device, this task can become part of the UCARP= scripts. This may be a good solution but security is a concern. 3. Find a way to make the FreeBSD nodes produce more than usual= gratuitous arp packets or add a line to do only that in the UCARP scripts.= Anyone have any thoughts on this or suggestions on how I may be able= to do this? I have tried by re adding the alias but this sometimes d= oesn't work until I again remove and readd the alias. Could it be a p= roblem with the alias addition not functioning properly? &= nbsp; Any input at all is greatly appreciated. Thanks, Colin =