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Persistence conflict


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Hello everyone,

Could someone please let me know how the ADC will address this Persistence case:

 

--> different persistence types set, example:

Front-End Content Switch VS that Persistence is set to COOKIE-INSERT have a lot of applications configured as policies

In some of those applications, I may have a VSLoad Balance that Persistence is set to SOURCE-IP.

 

What is the "real" persistence that will be applied? May that persistence conflict in some situations?

 

Thank you!

 

 

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Persistence at the CS-level affects CS decisions (and overrides future cs policy evaluation); LB persistence affects LB decisions (and overrides future lb decisions).

CS is evaulated before lb.  But they both work at different levels. See if the below clarifies.

 

Example 1:

If there was no persistence at the CS-vserver level, then a request that comes to the CS vserver is evaluated based on a CS policy and directed to the appropriate lb vserver.

That LB vserver makes a load balancing decision to its service (svc_a or svc_b), and the retaines that lb decision based on the lb persistence (source ip above).  Future requests from this client, will be load balanced to svc_a (for example) until persistence expires. Other clients will be load balanced separately on THIS lb vserver.

 

Example 2:

Persistence at the CS-vserver overrides additional cs policy evaluation.

So if client A makes a connection to the cs-vserver, and the first policy evaluates and sends traffic to LB vserver 1.  That cs decision is tracked in the cs cookie insert persistence cookie. The next request from client A, will then use the SAME CS decision as the previous cs policy evaluation, instead of being compared to the CS policies.

So additional transactions from client A are sent to lb vserver 1, regardless of what the cs policies say.  (LB persistence then affects the service decisions for traffic on this lb vserver).

 

Usually, you wouldn't want persistence on the CS vserver if your cs policies are sorting between lb vservers that act as separate applications.

It might be useful if the requests are all part of the same application but being "sorted" to different lb vservers, but get to the same backends (one app, with separate content).

Otherwise, you may not want to use cs persistence at all.

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One other follow up to your above post.  LB persistence is still set per lb vserver and is specific to the load balancing situation.

Usually persistence on cs vserver is not used; so only the lb persistence applies to transactions sent to that lb vserver. Separate destinations (lb vservers) track persistence separately.

 

CS vserver and LB vserver persistence don't conflict, but they work at different levels. And your cs persistence may mean traffic does not hit the lb vserver you expect.  The cs persistence is separate from lb persistence. (I think these last two points wrap up some loose ends from your original post; but I hope my first response clarified most of the considerations.)

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17 hours ago, Rhonda Rowland1709152125 said:

One other follow up to your above post.  LB persistence is still set per lb vserver and is specific to the load balancing situation.

Usually persistence on cs vserver is not used; so only the lb persistence applies to transactions sent to that lb vserver. Separate destinations (lb vservers) track persistence separately.

 

CS vserver and LB vserver persistence don't conflict, but they work at different levels. And your cs persistence may mean traffic does not hit the lb vserver you expect.  The cs persistence is separate from lb persistence. (I think these last two points wrap up some loose ends from your original post; but I hope my first response clarified most of the considerations.)

Thanks @Rhonda Rowland, that was extremely helpful.

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