check_catalyst_load.pl

This script monitors the load of a Cisco catalyst via SNMP.

It requests some data of a catalyst via SNMP to analyze them and notifies you via Nagios if the load is getting to high. To learn how to enable SNMP in your catalyst’s IOS scroll down.

This script should be called with -s [SWITCHIP] , -C [COMMUNITYSTRING] , -w [WARNLEVEL] and -c [CRITLEVEL] . For more information just run it with -h .

Tested with different IOS versions and SNMP protocol version 2c. If you want to use a different SNMP protocol version, just modify the Net::SNMP->session(...) call.

Here is the code.

How to enable SNMP in your catalyst's IOS

To allow an server to access the IOS via SNMP you have to create an access list with the IP of your server. Afterwards define the access to the IOS’s SNMP-server with an community string, similar like a passphrase. Here is an example configuration:

access-list 60 permit [IP-THAT-IS-ALLOWED-TO-REQUEST]
snmp-server community [COMMUNITY-STRING] RO 60

For more information just ask one of these search engines out there.

Dependencies

• Net::SNMP
• Getopt::Long

Please consider to take a look at my general setup notes.