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List:       loadbalancing-l
Subject:    RE: [load balancing] F5 BigIP Duplicated sessions?
From:       Brad Knotwell <b.knotwell () f5 ! com>
Date:       2003-02-05 20:41:13
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What are you using to identify a session?  Are you using cookies, the
SSL session id, ip address (AKA simple persistence), or something
identifiable via the Universal Inspection Engine?

Or do I still misunderstand the trouble you're having?

--Brad

On Wed, 2003-02-05 at 09:07, Massar, Marc wrote:
> I have received many requests for more information and some good tidbits
> to check out.  Here is a more detailed explanation.  
> We have a web layer pool built out on 3 separate physical web servers.
> I have 5 separate "web servers" spread out across these 3 physical
> servers.  Behind the web layer is my processing engine layer.  What
> should happen is my web layer sends a "session" to my processing engine.
> Each web server is supposed to send 1 session containing the transaction
> details to the VIP of the pool for the processing engine.  
> I gather logs from my processing engine that show all the details from
> the transaction...but duplicated.  1 instance of my transaction session
> on one server and another duplicate session on a separate server.  This
> can't happen because of the way web application layer is coded.  The
> BigIP is balancing all traffic into my web layer and balancing the
> traffic coming out of the web layer and into the processing engine
> layer.  The web layer can't double up the trans, so the only piece in
> front of my processing engine layer that can even move sessions is my
> F5.  
> Hence, I have two separate transaction threads with identical data but
> spread out on 2 separate real servers inside 1 VIP.  But the transaction
> data is for 1 unique order.
> 
> We are running least conns on the pool for processing engines.  I'm
> wondering if the BigIP checks for availability and possibly does not
> immediately send a session down a pipe to a VIP, but waits a fraction of
> a second and sends one connection down to one real server and because it
> paused for something then forgets about the first session it throws out
> and sends the second one.  The time frames I'm seeing are at most one
> second apart for the separate threads.
> 
> Some have asked how I figured out the sessions are duplicated...this is
> just logging.  The processing engine application dumps all the details
> for every thread that runs through the engine.  The order details are
> laid out and I can match up the transactions item by item.  
> 
> I appreciate the help...
> -Marc 
> 
> -----Original Message-----
> From: Brad Knotwell [mailto:b.knotwell@f5.com]
> Sent: Tuesday, February 04, 2003 1:44 PM
> To: Massar, Marc
> Subject: Re: [load balancing] F5 BigIP Duplicated sessions?
> 
> 
> Hi Marc--
> 
> You'll need to be more specific.  With the current level of information,
> I'm unable to understand what your problem is.
> 
> Good luck!
> 
> --Brad
> 
> On Tue, 2003-02-04 at 13:26, Massar, Marc wrote:
> > I know this sounds weird, but has anyone ever seen the BigIP build a
> second, duplicate session and send both sessions to different servers?
> > I am running 4.2 I think (I don't have direct access right now), it's
> a bit of an older box, but hasn't been too troublesome.  We have the
> Rainbow SSL cards in the box, but don't ever push over about 100 SSL
> connections per second.
> > I don't have a lot of detail because my problem is pretty sporadic
> (does not follow heavy load either).  Any help would be appreciated.
> > -Marc
> > 
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