Date: Sun, 25 Mar 2007 19:23:50 +0100 (BST) From: "Ross Draper" <ross@virtualgeek.net> To: freebsd-cluster@freebsd.org Subject: Vrrp/CARP/UCarp Problems Message-ID: <48279.83.104.128.109.1174847030.squirrel@virtualgeek.net>
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Hi guys I was wondering if I could get some advice from those of you who have successfully implemented ip address failover systems such as carp and freevrrpd. I am trying to set up a high availability web loadbalancer using a pair of freebsd 6.2 boxes. I have tried a number of ways to perform failover but always seem to be hitting a problem. UCARP - Pro's:This would be my ideal solution as the startup/shutdown scripts enable me to stop and start my applications and add aliases to adaptors easily. Cons: When the backup box is rebooted it always comes up advertising itself as the master then after a few seconds revers to backup, although I was under the impression it was supposed to wait and listen for advertisements(it doesnt seem to). Its initial gratuitous arp as a master is sufficient to poison any traffic from the local router to the shared ip address. Only solution was to use arp-sk to send gratuitous arps every few secs, however, arp-sk was a bit flakey and it was a bodge. CARP - Pro's: stable and built into the kernel. Could enable acive/active arp load sharing at a later point. Cons: There is a Freebsd bug (I've seen it discussed on the lists where the creation and destroyal of a carp interface causes a kernel panic. Also, there is no support for start/stop scripts. Freevrrpd - Pros: Mac address changing removes some of the arp timeout issues/gratuitus arp problems and it supports start/stop scripts Cons: I'm finding that upon rebooting the backup unit it correctly starts as a backup, then three seconds later syslogs that it is the master and changes its mac address accordingly. although a sniff of the network traffic indicates it is sending the right advertisements, it never goes into backup mode again. So, what am I doing wrong? are these the experiences others have had or are there more suitable options? the loadbalancers are all single homed and I have tried a mixture of xl, bge and fxp cards. Also, any links to a perl based gratuitous arp utils would be great Any help/suggestions much appreciated. Ross
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