Configuring Virtual Server in Active-Standby (or failover) mode

I have a similar situation and have previously configured the Active/Standby and it works properly except for one issue. I've got two LDAP servers, not using the iApp for LDAP, but a simple VS and monitor checking port 389.

My problem is that the primary server, if the LDAP service is disabled, takes too long to mark the server down before the Standby server becomes active. It's obviously the monitor taking too long to mark the server down. I don't want to set the timeout too low and get false positive failovers.

We have a similar setup on our ACE which we are migrating from and it works perfectly there using the same timeout settings. My end user has a script that is doing repeated LDAP queries where he ran it against the ACE and there was no interruption and then on the F5 where he clearly lost connection until the standby server comes up.

Any advice would be appreciated.

Steve