Tech Tip: Monitoring network equipment hardware

This month Anders provides insight on monitoring network equipment hardware like switches and routers via SNMP.

In many organisations the availability of IT-services depend on network eqipment that happens to work well, but isn’t proactively monitored. The switches and routers in question are usually quite expensive hardware with well implemented SNMP interfaces, but two things seem to prevent most organisations from adding monitoring of these devices: 1 – They haven’t had any problems with the equipment (yet), and 2 – The software provided by the hardware manufacturer to monitor these devices is too expensive or too complex, when compared to the needs of the organization.

Monitoring the hardware of your network equipment doesn’t have to be either expensive or complex, since there are some very useful Nagios plugins out there:


Check_snmp_env has been around for a couple of years now and version 1.2 has proven very useful when monitoring (for example) a mix of Cisco switches. The plugin can monitor Cisco, Nokia Ipso, Bluecoat, Ironport and Foundry hardware.

In the case of Cisco hardware, it monitors fans, power supplies (including RPS-modules) and temperature. It has been successfully tested on the most commonly used models, ranging from cisco-1811 to cisco-4503.

The functionality has been futher extended by two other plugins;
This is based on the ‘check_snmp_env’ script with the addition to check Cisco and Extreme hardware blades/modules and all hardware components for Juniper equipment. When it comes to Cisco hardware, it monitors both the modules of the supervisor and the blades (for example, cisco-4500 and cisco-6500).
This plugin provides temperature logs combined with the SNMP-location (in performance data format),and hence is very useful when it comes to graphing and keeping an eye on the temperature in all the small dusty locations where you might have had to place your network equipment. The plugin has been successfully tested on cisco-2811 and beyond.
Plugin Downloads:,-Extreme-and-Juniper-hardware/details

About the Author:
Anders is the lead of the Nagios support team.  With years of professional Nagios experience behind him, there’s not much that can stump him with monitoring.  Look for more tech tips from Anders in the future!