If you are not fortunate enough to have equipment that supports Cisco NetFlow technology, but still need to know bandwidth utilization statistics across network links, then there may be no better solution than the combination of SNMP and MRTG.
MRTG (or Multi Router Traffic Grapher) is a free software tool, developed by Tobias Oetiker, that uses SNMP (Simple Network Management Protocol) to poll network devices. MRTG stores the retrieved data to a log file, where it then generates a graphical representation of the stored data.
There are several third party network monitoring tools, like Denika, that use MRTG and SNMP as the means to capture this valuable data. In Denika’s case, the functionality of MRTG is expanded on by incorporating a MySQL database, which provides long term data storage.
If you have ever used MRTG, then you know that it is not easy to configure. MRTG uses a system of templates to send the neccessary object identifiers (OIDs) to the device, which then must have a MIB (or management information base).
Plixer has gone a long way to simplifying this process by making its database of MRTG templates available on the web. In Plixer’s MRTG repository, one can browse a number of different vendors, hardware models and templates. So whether you want to gather port utilization information on your Adtran devices, or frame relay utilization on your Cisco Catalyst 6509, or maybe just CPU utilization on your Foundry BigIron switch, it’s much easier to configure MRTG using Plixer’s MRTG repository.