Try just "interfaces" in your snmpwalk instead of the OID. If you don't have the standard MIBs installed in your SNMP server, you should find the interfaces here: 184.108.40.206.4.1.6220.127.116.11.1.3
I just wanted to check back in with you on this post. Were you able to find a way to walk the interfaces with SNMP? Typically just the standard MIBs will work for this.