Re: [load balancing] SI Foundry L4-Check / vip flapping

From: Bjørn Mork <bjornIZZATmork.no>
Date: Thu Apr 21 2005 - 03:04:44 EDT

"Youri Pasquier" <ypasquier@ile-des-medias.com> writes:

> I am triing to understand theses L4-Check logs on a foundry XL (old Version
> 07.1.08T12 from 2000)
>
> The real servers are running but the L4-check seems to often see them down
> (never longer than 5 seconds) :
>
> Apr 20 18:41:47:N:L4 server 10.0.120.142 idm6c-1 port 80 is down
> Apr 20 17:31:50:N:L4 server 10.0.120.142 idm6c-1 port 80 is up
> Apr 20 17:31:43:N:L4 server 10.0.120.142 idm6c-1 port 80 is down
> Apr 20 17:21:44:N:L4 server 10.0.120.142 idm6c-1 port 80 is up
> Apr 20 17:21:44:N:L4 server 10.0.120.142 idm6c-1 port 80 is down
> Apr 20 17:01:42:N:L4 server 10.0.120.148 idm6c-3 port 80 is up
> Apr 20 17:01:42:N:L4 server 10.0.120.142 idm6c-1 port 80 is up
> Apr 20 17:01:38:N:L4 server 10.0.120.142 idm6c-1 port 80 is down
> Apr 20 17:01:34:N:L4 server 10.0.120.148 idm6c-3 port 80 is down
> Apr 20 16:51:47:N:L4 server 10.0.120.151 idm6b-4 port 80 is up
> Apr 20 16:51:46:N:L4 server 10.0.120.146 idm6a-3 port 80 is up
> Apr 20 16:51:46:N:L4 server 10.0.120.141 idm6b-1 port 80 is up
>
>
> (there are no L7 check in the configuration, only l4)

The ServerIron defaults to doing L7 check for http. See
http://www.foundrynet.com/services/documentation/sixl/health-checks.html

It will send a "HEAD / HTTP/1.0" request unless you configure it
otherwise, and expect a status code in the range 200-299 or 401 in
return. Which means that many web server configurations will fail
because they respond to / requests with a 302 redirect.

Bjørn

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Received on Thu Apr 21 04:16:49 2005

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