Re: [lvs-users] Connection count mismatch between client and LVS

To: lvs-users@xxxxxxxxxxxxxxxxxxxxxx
Subject: Re: [lvs-users] Connection count mismatch between client and LVS
From: Khosrow Ebrahimpour <khosrow.ebrahimpour@xxxxxxxxxxxxx>
Date: Tue, 11 Dec 2012 09:20:43 -0500
Quick update: we found the issue thanks to David's hint and solved the 

On November 28, 2012 01:01:34 PM David Coulson wrote:
> How long do these TCP connections live for? Perhaps they are sitting there
> with no packets for 15mins (or whatever the TCP timeout is on LVS in your
> configuration). Based on the timers of the 3 you were able to see, they
> stick around a while without any activity.
> You could configure TCP keepalives on the server side so the connections
> have periodic traffic to update the LVS timers and avoid the LVS
> connections expiring before the connections are really closed on the
> server/client side.

That was exactly our problem. The real servers were using the default value 
for net.ipv4.tcp_keepalive_time which is 7200 seconds. And the LVS was using 
the default tcp timeout value of 15 seconds (seen using: ipvsadm -L --timeout)

I think our problem was made more complex due to the fact that our setup is 
using direct routing (LVS-DR), and so the connection from RIP -> CIP was 
staying open despite the fact that the LVS had timedout that particular 

Currently we've made the LVS TCP timeout value 7200 seconds, but I think as 
per the recommendation above, we'll make the tcp_keepalive_timeout on the real 
server shorter so that it will start to send keepalive packets before the LVS 


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