Interfaces showing up without any 'ifName' and only with 'ifIndex'. Also, the speed shows up as 'Unknown'.
The cause for this issue is that there is a device limitation which does not produce the data necessary for the subinterfaces to populate the information in question.
The resolution for this issue is to prove that NFA is working as designed by using a third party tool as follows:
1. Download and install Paessler SNMP Tester.
2. Run a Walk test with if type 18.104.22.168.22.214.171.124.1.3 to list the if type of all the interfaces
3. Run a Walk test with if description 126.96.36.199.188.8.131.52.1.2 to list the if description of all the interfaces
The test should show whether or not the device itself is producing the information in question.