RE: [load balancing] Simultaneous sessions with BIGIP simple persistence

From: Winter, R. Stephen <SWinter [izzat]>
Date: Mon Feb 27 2006 - 14:21:07 EST

As I understand it:

With simple persistense, the user will be forwarded to the same server
as long as the timeout hasn't expired. I don't know if that timer
resets everytime it see's a packet, or only when a new connection is
established, or it doesn't' reset it at all. Just from first overall

We have a web application that keeps "credentials" on the first server
you visit, so we have set the timeout for 8 hours, so they will always
stay on the same server for the entire day. We haven't had any problems
with users switching...

Without Persistence, every new connection would get balanced to a
potentially different server.

If the large file transfer is all one tcp connection, then it will not
get "reblanced" in the middle. The F5 only balances on TCP connections.
If the transfer is a number of files that each have a separate TCP
connection (ftp:mget), then they will get re-balanced once the timer is


> -----Original Message-----
> From: on behalf of Oleksandr Darchuk
> Sent: Mon 2/27/2006 7:04 AM
> To:
> Subject: [load balancing] Simultaneous sessions with BIGIP
> simple persistence
> Hello, all.
> Would you like to give me some advises for best understanding
> of persistence on load balancing...
> I my environment I have 5 proxy servers behind the BIGIP LB,
> round robin method and simple persistence.
> In log files I see, that when user start connection (retrieve
> first URL), all other URL's he retrieves from the same
> server. But sometimes (especially during big file downloads)
> user simultaneously start another connection and go through
> another proxy.
> So, as I understand, as usual requests go sequential (in
> terms of TCP connection), and because of simple persistence
> go through only one (the same) proxy. But during "long"
> request another simultaneous connection start and it goes
> through another proxy according to LB schema. Am I right?
> And another question: if I'll remove persistence at all, does
> it means that all another request will be passed through
> another proxy server?
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Received on Mon Feb 27 16:27:25 2006

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