Take server out-of-service and route new HTTP requests to one of the other servers

[marc000011]

Hi

We have several server farms configured on our ACE. We have sticky sessions configured based on either Hash Address or Least Connections. We also have TCP reuse enabled. When we take one server out of service, we can still see new HTTP requests going to the out-of-service server. We can explain this by the persistent HTTP connections (HTTP Keep-Alive).

What we want is that the currently executing requests can finish on the out-of-service server, but new requests should be handled by one of the other servers. The other servers may not drop their existing connections/sessions.

How can we force that new HTTP requests will no longer be deliverd to the out-of-service server? Will clearing the sticky table solve our problem? Or are there any other ways of accomplishing this?

[Kanwaljeet Singh]

Hi Marc,

The default behavior of ACE is to take the rserver out of loadbalancing if it fails or is taken "out of service". Only existing connections are allowed to complete or connections matching the sticky entry. All new connections are loadbalanced.

You can tell the ACE to either remove the connections or reassign it to another server if you configure a backup server in serverfarm.You can find details here:

http://www.cisco.com/en/US/docs/app_ntwk_services/data_center_app_services/ace_appliances/vA3_1_0/configuration/slb/guide/rsfarms.html#wp1117375

failaction {purge | reassign [across-interface]

Please visit section: "Configuring the ACE Action when a Server Fails" in the above link.

Regards,

Kanwal