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ACE - SNMP Server Load Probe

Naren naren
Level 1
Level 1

Hello Friends,

1) I have a concern on SNMP Server Load Probe, if i configure server CPU OID value ex:- 1.3.x.x.x.x, how the ACE will  recognise the the load vaule from server.

I know that we can configure the threshold value but how it will exactly recognise the CPU utlization.

2) what is the diffference between absolute value and percentile value.

Adavnce Thanks,

Naren

1 Reply 1

Telmo Pereira
Cisco Employee
Cisco Employee

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!

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