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Community Member

ACE sticky table and backup rserver

Hi All,

We have a ACE 4710 balancing traffic for servers. One of the use case is, two servers, server1 is the primary and server2 is its backup. We also use sticky table based on source IP.  Here is our configuration sample.

serverfarm host SF-farm1

  predictor leastconns

  probe PROBE-443

  rserver RS-server1

    backup-rserver RS-server2


  rserver RS-server2

    inservice standby

sticky ip-netmask address source STICKY-farm1

  serverfarm SF-farm1

  timeout 15

  replicate sticky

So, normally, server1 is in operational and server2 is in standby. When server1 is failed, server2 goes to operational state and connections go to server2. So far everything is running fine.

When server1 back to service,  Server1 is back to Operational state and server2 back to standby again. Now, here comes the question. when a new connection comes in, I am expecting it is being directed to server1. However, because in the sticky table it has entry to point to server2, the conn is still sent to server2.  I can see a new conn being establised to server2 from the show conn command.

Shouldn't the ACE check the server in operational state first, and then search sticky table according to the server status?  Is there any commond I missed?

Any comment is welcomed. Thanks for your help!

Cisco Employee

ACE sticky table and backup rserver

Hi Patty,

That is the expected behavior. New connection which don't match the sticky entries would be sent to the server1 but the connections which does match will stick to server 2. Otherwise it would break the persistence. Below is applying the command to primary server but behavior should remain same in your case as well.

The inservice standby command instructs the ACE to do the following:

•Tear down existing non-TCP connections to the server

•Allow current TCP connections to complete

•Allow new sticky connections for existing server connections that match entries in the sticky database

•Load balance all new connections (other than the matching sticky connections mentioned above) to the other servers in the server farm

•Eventually take the server out of service The inservice standby command instructs the ACE to do the following:



Community Member

ACE sticky table and backup rserver


   You can clear sticky database of that particular serverfarm using " clear sticky database " to remove the stickness from standby servers.


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