Si ton 3Com gère le SNMP, je te recommande Cacti. C'est simple et gratuit.
Regarde du côté de CactiEZ.
CactiEZ is a self installing Linux Distribution based off CentOS that sets up and configures a customized Cacti install. Everything is designed to be completely automated and working directly out of the box. This compact distro is loaded with extra features such as Syslog and Netflow data collection, Weathermaps, Reports, Auto Discovery, Router Config backup, Nagios, and much more! Both 32 Bit and 64 Bit installations are possible from the same CD.
This gives your system administrators more time to work on the real issues, and less time configuring and setting up your Monitoring System. Best of all, its absolutely FREE!