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Andy_304337's avatar
Andy_304337
Icon for Cirrus rankCirrus
Nov 09, 2018

Source address Affinity

Hey

 

I have a internal standard vip set up as gslb on gtm across dc A& B. I set source address affinity to 8 hours on both dc ltm. Now I added one pool member to each dc ltm.

 

So if a new client makes a connection request, how does source persistence behave new & existing conne tion requests ?

 

application delivery
BIG-IP
LTM
  • Philip_Jonsson's avatar
    Philip_Jonsson
    Icon for MVP rankMVP
    Nov 09, 2018

    Hey Andy

     

    Just so that I understand correctly, Source Address Persistence is configured on the LTM devices?

     

    The persistence table timeout value works using "Idle" timeout. So even though you have a timeout of 8 hours, as long as the same client source IP hits the VS, the timeout value will be reset to 0. Therefore, for the existing connections, they will continue to remain on pool member 1 until they have been idle for 8 hours.

     

    Once the persistence record has been deleted due to the timeout, when a new request hits the VS it will load-balance the traffic and choose either member 1 or member 2. In this case, traffic could end up at member 1 again. If you want to make sure that traffic ends up at member 2 you have to either Disable member 1 (active and persistent connections is still allowed) or set it to Forced Offline (only active connections is allowed).

     

    The problem with Source Address persistence, if your clients originate from a NAT device, they will come from the same source IP address and the it will be tougher for the timeout to occur.

     

    I hope this helps! :)