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Stickiness Doubt...

ahmed.gadi
Level 1
Level 1

serverfarm host W-1_SERVERFARM
  probe HTTP_PROBE
  rserver S-1
    inservice
  rserver S-2

    inservice

sticky ip-netmask 255.255.255.255 address both W-1_STICKY
  serverfarm W-1_SERVERFARM

policy-map type loadbalance first-match LB-1
  class class-default
    sticky-serverfarm W-1_STICKY

I have above config on my ACE module.

When both S1 and S2 are UP,ACE will do load balance in round robin fashion.

Lets say i have a open connection from client PC on S1 and at same time S1 SHUTDOWN, after  passdetect interval of HTTP_PROBE, ACE will automatically connects client to S2.

Now if i want to test another connection from same client pc without clearing cookies on client PC and S1 is UP, client request goes to S2 not S1.

In my understanding it is correct as client pc has still cookies pointing towards S2, it will always go to S2 because of stickiness untill and unless S2 is down..

PLEASE CORRECT ME IF I AM WRONG ... hope to hear from someone to justify myself over this logic.

Regards

Ahmed...

3 Replies 3

Surya ARBY
Level 4
Level 4

I guess you're right (even if  didn't test specifcally that). As the persistance cookie is set by the ACE on each response, when S1 comes up, the client still send the cookie leading to S2.

cpomeroy
Level 1
Level 1

The configuration you supplied is for IP sticky so cookies won't matter to the ACE.    Having said that, when client A connects to the VIP and is loadbalances to server A, a sticky entry for its IP address will be created.  Now if Server A is down and the client reconnects, it will be sent to Server B and a new entry will be added.  As long as the sticky timeout has not expired, the client will go to Server B even if Sever A is up.

many thanks christopher,

                   If i clear the cookies, it goes to Server A once Server A comes online. Please do you any show commands to clarify.

Thanks

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