The environment consist of 2 IDGs devices and one Linux Red Hat server as a consumer. The current DataPower firmware is IDG.220.127.116.11.
The only page for SNMP is the one below. The most important part is the user configuration which I will show you right after:
See that the "Local IP Address" is my outbound interface. Port is the default one, 161, SNMP version is the v3 and security level is "Authentication, No privacy". Those are the values I used as an example, you can change it if needed. Attention, this is only to make sure DataPower is configured correctly. This is not a SNMP tutorial. :)
Now go to your server (Linux Red Hat with snmp-net) and run:
#snmpgetnext -v 3 -u snmp-pooling -a MD5 -A "snmppooling" -x DES -X "snmppooling" -l authNoPriv 10.136.51.214 .18.104.22.168.4.1.14622.214.171.124.1.2
#SNMPv2-SMI::enterprises.146126.96.36.199.1.2.1 = STRING: "admin"
See that the password: snmppooling was setup in the previous page of DataPower. Replace also the IP address from the command below by your DataPower IP address. The .188.8.131.52.4.1.146184.108.40.206.1.2 is the ObjectID value, you can get it opening the .txt files from SNMP Setting > Enterprise MIBs tab. See screenshot:
You can open such file in the MibBrowser, you can get more details about this tool here: http://integrationyay.blogspot.de/2014/04/datapower-testing-snmp-using.html, loading the file in this free tool, you will see the Object ID values in a more friendly way.
See an example screenshot: