netflow v5 and pppoe interface number.

Hi!

In SNMP I see these interface numbers:
IF-MIB::ifName.15746085 = STRING: pppoe-and@server1
IF-MIB::ifName.15816524 = STRING:
IF-MIB::ifName.15844525 = STRING:
IF-MIB::ifName.15844556 = STRING: pppoe-dffg@dk

15746085, as example - its uint32.
netflow v5 format “SNMP index of input/output interface” should be uint16.

How to understand what the interface number is actually listed in the netflow packet?