You can use the show snmp mib ifmib ifindex to map or retreive the interface MIB in a Cisco router without performing an SNMP walk from a NMS.
4321#show snmp mib ifmib ifindex
GigabitEthernet0/0/1.40: Ifindex = 22
GigabitEthernet0/0/1.13: Ifindex = 21
Voice Over IP Peer: 22: Ifindex = 35
Voice Encapsulation (POTS) Peer: 1004: Ifindex = 30
Foreign Exchange Station 0/1/2: Ifindex = 10
Voice Over IP Peer: 20: Ifindex = 24
Voice Encapsulation (POTS) Peer: 1006: Ifindex = 32
Foreign Exchange Station 0/1/0: Ifindex = 8
GigabitEthernet0/0/0: Ifindex = 1
Service-Engine0/1/0: Ifindex = 3
GigabitEthernet0/0/0.4: Ifindex = 19
GigabitEthernet0/0/0.3: Ifindex = 16
VoIP-Null0: Ifindex = 6
Null0: Ifindex = 7
