Re: Fwd: inconsistent behaviour with failover on 2 combo router-server nodes?

Are you using conntrackd?


On Wed, Jan 22, 2014 at 3:09 PM, Alexander Ufimtsev <[email protected]> wrote:
> Hello All,
>
> I'm running keepalived on two nodes that work both as routers and servers,
> using lo:0 interface for virtual ip and iptables to mark packets for real
> servers. Server 1 has priority over server 2 and thus control the virtual
> ip. The workload consists of clients establishing a long-running tcp
> connections to the servers.
>
> I've noticed an interesting behavour during failover: when server 1 fails
> over, all existing tcp connections to server 1 are gone and clients
> reconnect to server 2, which is 100% correct and expected behaviour.
> However, when server 1 comes back and takes over virtual ip, some clients on
> server 2 get disconnected and then have to dial back to server 1. This seems
> to happen only for clients that connected to server 2 when server 1 was
> offline. The clients that were connected to server 2 before server 1 went
> down remain connected to server 2.
>
> Is this due to the fact that before server 2 takes over virtual ip on eth0,
> clients bind to lo:0 and after virtual ip takeover they bind to virtual ip
> on eth0? If so, is there any way to teach them to bind to lo:0 instead so
> they do not disconnect the moment another server takes over the virtual ip?
>
> Many thanks,
> Alexander
>
> --
> Alexander Ufimtsev
> School of Computer Science and Informatics
> University College Dublin, Belfield, D4, Ireland
> Phone: +353 1 716 2926  Fax: +353 1 269 7262
>
>
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