How to get Interfaces’ ifIndex values via SNMP

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To obtain list of ifIndex values for all interfaces for given device SNMP polling agent has to send

SNMP GET BULK request for the following OID:  .1.3.6.1.2.1.2.2.1.1

Response Example:

‘.1.3.6.1.2.1.2.2.1.1.1’ => “1”
‘.1.3.6.1.2.1.2.2.1.1.2’ => “2”
‘.1.3.6.1.2.1.2.2.1.1.3’ => “3”
‘.1.3.6.1.2.1.2.2.1.1.4’ => “4”
‘.1.3.6.1.2.1.2.2.1.1.5’ => “5”
‘.1.3.6.1.2.1.2.2.1.1.6’ => “6”
‘.1.3.6.1.2.1.2.2.1.1.7’ => “7”
‘.1.3.6.1.2.1.2.2.1.1.8’ => “8”
‘.1.3.6.1.2.1.2.2.1.1.9’ => “9”
‘.1.3.6.1.2.1.2.2.1.1.10’ => “10”
‘.1.3.6.1.2.1.2.2.1.1.11’ => “11”
‘.1.3.6.1.2.1.2.2.1.1.12’ => “12”
‘.1.3.6.1.2.1.2.2.1.1.13’ => “13”
‘.1.3.6.1.2.1.2.2.1.1.14’ => “14”
‘.1.3.6.1.2.1.2.2.1.1.15’ => “15”
‘.1.3.6.1.2.1.2.2.1.1.17’ => “17”

Next Step is to get Interface names by sending SNMP GET BULK request for the following OID:  .1.3.6.1.2.1.2.2.1.2

Response Example:

‘.1.3.6.1.2.1.2.2.1.2.1’ => “TenGigabitEthernet0/0/0”
‘.1.3.6.1.2.1.2.2.1.2.2’ => “TenGigabitEthernet0/0/1”
‘.1.3.6.1.2.1.2.2.1.2.3’ => “GigabitEthernet0/0/0”
‘.1.3.6.1.2.1.2.2.1.2.4’ => “GigabitEthernet0/0/1”
‘.1.3.6.1.2.1.2.2.1.2.5’ => “GigabitEthernet0/0/2”
‘.1.3.6.1.2.1.2.2.1.2.6’ => “GigabitEthernet0/0/3”
‘.1.3.6.1.2.1.2.2.1.2.7’ => “GigabitEthernet0/0/4”
‘.1.3.6.1.2.1.2.2.1.2.8’ => “GigabitEthernet0/0/5”
‘.1.3.6.1.2.1.2.2.1.2.9’ => “Crypto-Engine0/0/8”
‘.1.3.6.1.2.1.2.2.1.2.10’ => “GigabitEthernet0”
‘.1.3.6.1.2.1.2.2.1.2.11’ => “Null0”
‘.1.3.6.1.2.1.2.2.1.2.12’ => “Port-channel1”
‘.1.3.6.1.2.1.2.2.1.2.13’ => “Port-channel2”
‘.1.3.6.1.2.1.2.2.1.2.14’ => “Port-channel2.599”
‘.1.3.6.1.2.1.2.2.1.2.15’ => “Port-channel2.11”
‘.1.3.6.1.2.1.2.2.1.2.17’ => “Port-channel2.3213”

Now we are able to match Interface name to an ifIndex value.

Please note unless ifIndex persistence is enabled router (or switch) may assign different ifIndex value to the same interface after reboot.

To enable consistent ifIndex-to-Interface mapping ifIndex persistence must be enabled.

Configuration example for Catalyst 6500

Router(config)# snmp-server ifindex persist

Globally enables SNMP ifIndex persistence.

 

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