HASH Carp Persistence

Just Found this http://support.f5.com/kb/en-us/solutions/public/12000/000/sol12078.html FastL4 virtual servers stop processing traffic after a hash persistence profile is applied.

Does the above also apply when using CARP?

Thanks for your help

Is there any other persistence method i can use for a long lived application using ssl (SSL offloading is not an option.) also taking into account even distribution of load to all pool members in a pool.

without ssl offloading, persistence method is limited. i do not think you have much choice.

Is there any other persistence method i can use for a long lived application using ssl (SSL offloading is not an option.) also taking into account even distribution of load to all pool members in a pool.

there would be chances of uneven load balancing, correct?

yes

So if it bypasses load balancing method, there would be chances of uneven load balancing, correct?

But this will work if the LTM gives us the same pool member based on the Load balancing algorithim like Round Robin, Least Connections, which is not the case as it may select any pool member.

i understand load balancing algorithm won't be taken into account when using carp except ratio based with carp which is introduced in 11.3.0.

Ratio based load balancing with CARP persistence

Cache Array Routing Protocol (CARP) Persistence now leverages pool member ratio to enhance traffic distribution to heterogeneous server pools. Administrators can direct more traffic to more capable servers. The pool member's ratio is considered when calculating the hash value in the CARP mode of hash persistence.

Release Note: BIG-IP LTM and TMOS 11.3.0

Ok. I got it Once a hash of the pool member and Source Ip is calculated it will remain constant and map to the same pool member, until it goes down. But this will work if the LTM gives us the same pool member based on the Load balancing algorithim like Round Robin, Least Connections, which is not the case as it may select any pool member.

so how does it consistently map to the same pool member based on source ip? The hash value needs to be stored, correct?

key and pool member both are included in hash algorithm. the highest score will be chosen. so, the same pool member will always be picked as long as it is up.

3. Routing Function

  Once an agent has a Proxy Array Membership Table.  It uses a 
  mathematical hash function to determine which of the members of 
  the array should be the receptacle of a particular URL request.

  This routing function involves constructing n "scores" using a hash
  of the request URL plus a hash of each of the k proxies in the Proxy
  Array Membership Table.  

  Both the URL and the proxy names are hashed in order to minimize the
  disruption of target routes if a member of the target array can't
  be contacted.

  Hashes of the URL and proxy name are constructed using the algorithm
  described in 3.1 and combined using the algorithm described in 3.2.

3.4. Route Selection

  The "score" for a particular combination of URL plus proxy is its
  resultant value. Once the agent determines the scores of the 
  K proxies, it routes the URL query to the proxy with the highest 
  score.

Cache Array Routing Protocol v1.0

so how does it consistently map to the same pool member based on source ip? The hash value needs to be stored, correct?