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I'm not very familiar with routers, and my searches have proven a bit futile currently. I was tasked to create a monitor for our router. I've used the following OID's to obtain the relevant information on the different interfaces I wanted to monitor

1.3.6.1.2.1.2.2.1.10
1.3.6.1.2.1.2.2.1.16
1.3.6.1.2.1.2.2.1.2

I figured out that you have to add the interface index at the end of the OID to get a specific interface's information (eg. 1.3.6.1.2.1.2.2.1.10.2)

My problem that I'm having at this point is that the interface of the other router I have to monitor have subinterfaces configured on a physical interface. When I sh int I can see the subinterfaces on the interface. Here is the information

FastEthernet0/0/0 is up, line protocol is up
  Hardware is FastEthernet, address is
  MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec,
     reliability 255/255, txload 1/255, rxload 6/255
  Encapsulation 802.1Q Virtual LAN, Vlan ID  1., loopback not set
  Keepalive set (10 sec)
  Full-duplex, 100Mb/s, 100BaseTX/FX
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:01, output 00:00:00, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 2505000 bits/sec, 364 packets/sec
  5 minute output rate 631000 bits/sec, 282 packets/sec
     5907895 packets input, 630428948 bytes
     Received 8168 broadcasts (0 IP multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog
     0 input packets with dribble condition detected
     5162711 packets output, 1548903164 bytes, 0 underruns
     0 output errors, 0 collisions, 2 interface resets
     1135 unknown protocol drops
     0 babbles, 0 late collision, 0 deferred
     1 lost carrier, 0 no carrier
     0 output buffer failures, 0 output buffers swapped out
FastEthernet0/0/0.10 is up, line protocol is up
  Hardware is FastEthernet, address is 
  Description: VodacomPTP
  Internet address is 
  MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec,
     reliability 255/255, txload 1/255, rxload 6/255
  Encapsulation 802.1Q Virtual LAN, Vlan ID  10.
  ARP type: ARPA, ARP Timeout 04:00:00
  Keepalive set (10 sec)
  Last clearing of "show interface" counters never
FastEthernet0/0/0.20 is up, line protocol is up
  Hardware is FastEthernet, address is 
  Description: Vodacom2Mbps
  Internet address is 
  MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec,
     reliability 255/255, txload 1/255, rxload 6/255
  Encapsulation 802.1Q Virtual LAN, Vlan ID  20.
  ARP type: ARPA, ARP Timeout 04:00:00
  Keepalive set (10 sec)
  Last clearing of "show interface" counters never
FastEthernet0/0/0.30 is up, line protocol is up
  Hardware is FastEthernet, address is 
  Description: Vodacom4Mbps
  Internet address is 
  MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec,
     reliability 255/255, txload 1/255, rxload 6/255
  Encapsulation 802.1Q Virtual LAN, Vlan ID  30.
  ARP type: ARPA, ARP Timeout 04:00:00
  Keepalive set (10 sec)
  Last clearing of "show interface" counters never

I found in MIB on this forum for ifHCInOctets and ifHCOutOctets, but I'm not sure how I should interrogate this. Because to start the MIB is already longer than the normal ifInOctets MIB.

Do I have to enable SNMP for say FastEthernet0/0/0.20. What MIB do I have to use to get the InOctets information for instance. And lastly do I still have to add a .1 in the index for the 1.3.6.1.2.1.31.1.1.1.6 MIB.

  • I would recommend you get a tool to browse snmp on the device. On linux you could use snmp-walk. When you browse the device/mib you will find the interface names and there index's. – Pieter Jul 17 '15 at 21:19
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rtr1841#show snmp mib ifmib ifindex 
Loopback1: Ifindex = 10
Tunnel0: Ifindex = 5
Serial0/0/0: Ifindex = 7
FastEthernet0/1: Ifindex = 2
FastEthernet0/0.2: Ifindex = 8
Loopback0: Ifindex = 6
Null0: Ifindex = 3
NVI0: Ifindex = 4
FastEthernet0/0: Ifindex = 1
FastEthernet0/0.3: Ifindex = 9

That's the quickest way to find the correct ifIndex for an interface on an IOS router. (That information is also found in the IF-MIB tables.)

Note: make sure snmp-server ifindex persist is in your config, or the indexs could change after a reload.

| improve this answer | |
  • Thank you very much Ricky for this information. I was able to pick up the FastEthernet0/0/0.10, .20, and .30. I don't see any real data yet, but I was just told that we have a problem with the provider. Will monitor it, but It seems like this gave me the solution. – Jaques Jul 20 '15 at 6:38

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