network topology software

[net_user]

i have a different models of switchs on my lan/wan , cisco,hp,nortel ect ect

is there any recommendations, (free) for some topology mapping software?

something like the Cisco Network Assistant software that can connect to cisco switches through the snmp commuities or something like that.

[tain]

nmap and the zenmap GUI are amazing and free.

http://nmap.org

http://nmap.org/book/zenmap-topology.html