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Michael_Whidden's avatar
Michael_Whidden
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Aug 07, 2014

F5 GTM Persistence TTL - Is it an Idle Timeout?

When a persistence TTL is configured for GTM, is the TTL computed from the first time a customer visits, or is it computed from the most recent time the customer has visited? I'm concerned about a 3600s TTL timing out on a source IP that is actively making HTTP connections over a 1 hour time period, and GTM flipping the customer over to another pool.

 

  • The expires time on the persistence record does not appear to increment with subsequent DNS requests, so I would say it is computed from the first time, not the most recent time.

     

    Generally the larger problem than this is what happens when the client's LDNS changes in the middle of their session? Using Topology or Geo rules would seem a safer method to try and make sure they stay on the same LTM.

     

9 Replies

  • Persitence will kep the user till the timeout set . First time user tries to access the f5 will set a entry for persistence . I think the request will be coming from Ldns on behalf of client . so the next time user tries to access then it will resolve to same ip .

     

  • The expires time on the persistence record does not appear to increment with subsequent DNS requests, so I would say it is computed from the first time, not the most recent time.

     

    Generally the larger problem than this is what happens when the client's LDNS changes in the middle of their session? Using Topology or Geo rules would seem a safer method to try and make sure they stay on the same LTM.

     

    • Michael_Whidden's avatar
      Michael_Whidden
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      Thank you for your answer, but it seems to be exactly the opposite of the answer posted by user 'raj' a little after you. Can you clarify?
    • mimlo_61970's avatar
      mimlo_61970
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      My answer is based on observation on my GTM running 11.2.1 I created a WideIP and querried it. I then checked the persistence record on the GTM and noted its experation, which was 1 hour in the future. I made additional queries to the GTM and the experation did NOT increment. I did this for 10-15 minutes and the persistence experation never changed. I may very well be wrong, but based on observation I do not see the persistence record getting extended out with each subsequent dns query.
  • if persistence set on a wideip, when ever the first request from ldns or end workstation , it will add an entry in persistence table. and for all the request coming from same ldns or end workstation , it will give same record.if there is no request until timeout value the persistence record will expire.

     

    for example : if we have 3600 sec ttl and gtm given a resolution for wideip. It stores the record in persistence table. Again if the request came from same ldns or end workstation at 3599 sec, persistence timeout will be again start from 0 to 3600

     

    • Michael_Whidden's avatar
      Michael_Whidden
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      Thank you for your detailed answer, but as I commented to mimlo, your answer conflicts with theirs. Can you clarify?
  • Mauz's avatar
    Mauz
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    You can test it by setting a low ttl (60 seconds) and see if it times out completely or reset its counter