Stateless session persistence

Hi,

 

 

I'm trying to set up session persistence in such a way that it doesn't depend on a state table in LTM. This is so that persistence will work when a client moves to a different LTM, when the LTMs aren't in a cluster. (This is for OSPF failover, but this is irrelevant.)

 

 

What I basically want to do is to insert (an obscured version of) the backend server's IP into a cookie and then persist just by going to whatever server is specified in the cookie (with some logic to handle the server going down).

 

 

Before I go on, maybe I should just ask at this point: how would I do this? I'm new to F5, and in some cases, I can make something work, but it just feels wrong, so I'd rather not share my code at this stage.

 

 

I've tried creating a universal persistence profile with a rule that looks at the cookie and says "pool [ LB::server pool ] member $foo". However, I also have a rule which selects a pool based on the URL. With this set-up, the persistence rule runs first and the result is that it's messed up when the pool selection rule says "pool foo".

 

 

The way I got it to work is by having no persistence profile and just attaching the persistence rule to the vserver, and making it run after the pool selection rule.

 

 

However, this just feels Wrong. It also won't be very transparent when someone else comes to look at the config (this is something we were really hoping to achieve by replacing our old load balancers with F5).

 

 

Another related question: what is the difference between "pool $pool member $member" and "LB::reselect pool $pool $member"?

 

 

I'd be very grateful for any suggestions.

 

 

 

Alex