Not a perl solution (Tcl), but I thing worth a look, is Scotty / Tkinet. A quote from the Tkinet description:

Network maps can be maintained by using the editing features
provided by Tkined or using automated tools. The source 
distribution contains applications to discover IP networks, 
to support the network layout process, to troubleshoot IP 
networks using SNMP in combination with other standard tools
(e.g. traceroute) and to monitor network status using SNMP 
or selected SUN RPCs.
[download]

Might be interesting to use together with Tcl::Tk, if you want to do this in perl.