Unanswered Question
Jul 20th, 2009


we have setup ACE 4710 in one-arm mode with redundancy.when the active LB fails,the standby takesover immediately.But again when the actve LB is online,it takes 3 mts to switch over.Is this due to any configuration issue?

The configurations are identical on both LB's.let me know if i need to provide more info.


I have this problem too.
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dario.didio Mon, 07/20/2009 - 05:08


did you configure any FT tracking?

If you did, than it is probably the timers of the probe used for the tracking that is causing the delay.

Can you post your config relevant to the FT?



dario.didio Mon, 07/20/2009 - 06:27


can you also post the config of the probe HA-TEST.

The default passdetect timers of a probe are 300 seconds and 3 counts.

Assume that your ace can't the device that is probed anymore. The probe goes down, and 200 is deducted from the priority from the active, making the standby having the higher priority and making it active.

From the moment the probe goes down, the passdetect interval starts. This means that every 300 seconds it tries to reach the probed device.

If it is reachable again (if the probe is successful again), it needs 3 consecutive successful probes to make the probe go from Failed to Success, raising the priority again and becoming again active ACE.

These are the default timers.

If you have a probe with a faildetect of 1 minute and a count of 3, it takes 3 minutes to become the active ACE again when the probe failed.



sarsamivel Mon, 07/20/2009 - 22:21

Hi,Thanks for tht info.Here is the probe config.

probe icmp HA-TEST

interval 60

passdetect interval 60


dario.didio Tue, 07/21/2009 - 22:51

Because you have confiogured a passdetect interval of 60 seconds, and the default passdetect count is 3, from the moment the tracked object becomes reachable again, it is going to take 3 minutes (3 times 1 minute) before the ACE will increment its priority again and claiming the active role again.

Please rate if this was helpful for you.



sarsamivel Wed, 07/22/2009 - 04:09

If i need to reduce the time,what will be the most appropriate config.?

It did helped me a lot,rated.


dario.didio Wed, 07/22/2009 - 05:04


it all depends on what you want. In your initial question you have stated that when the active ACE fails, the standby immediately takes over the active role, which is a good thing.

When it returns, it is a good thing to have it standby for a while. During this time, the C6500 which houses it can converge on STP, routing protocols etc, while client traffic is being served by the other ACE.

Compare it with HSRP preempt delay on a router.



sarsamivel Wed, 07/22/2009 - 06:09

hello dario,

We have cisco 4710 appliance and not module.

I tried disabling the preempt option but even after tht it's trying to take the active role.Anyidea what wil be the reason ?


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