Hello Naren,
First and foremost, for you to base the loadbalancing decision of your ACE on SNMP Server load you need to configure the ACE predictor as
#predictor least-loaded probe
this is accomplished under serverfarm configuration mode.
Then the ACE will use SNMP probes to query the real servers for load parameter values (CPU utilization, memory utilization,...).
To use this predictor, you must associate an SNMP probe with it as ilustrated.
---------
probe snmp CPU_SERVERS
interval 15
passdetect interval 60
community Public
oid 1.3.6.1.2.1.25.3.3.1.2.x
threshold 40
serverfarm SF1
predictor least-loaded probe CPU_SERVERS
---------
The ACE uses the retrieved SNMP load value to determine the server with the lowest load.
If the retrieved value is within the configured threshold, the server is marked as passed. If the threshold is exceeded, the server is marked as failed.
Depending on the MIB support on the server you might need to use a percentage or an absolute value. For that you just need to check the MIB on the Server and decide what is supported and what would work best for you.
There are a few parameters you can tweak here, for instance you might want to query several OIDs and under such circumstances you would need to define the weight for each OID. The weight sum of all OIDs should always be 16000.
More details can be found here:
http://www.cisco.com/en/US/docs/interfaces_modules/services_modules/ace/vA4_1_0/configuration/slb/guide/rsfarms.html#wp1023940
http://www.cisco.com/en/US/docs/interfaces_modules/services_modules/ace/vA4_1_0/configuration/slb/guide/probe.html#wp1100334
Hope this helps!
Regards!
