Tip of the Trade: Netdisco
Admins of medium to large networks ought to try out Netdisco, which has nothing to do with dancing and everything to do with network discovery. Netdisco is an open source Web-based network management tool that uses SNMP, Cisco Discovery Protocol (CDP), and DNS polling to automatically map the network. Put away the bell bottoms and lava lamps, Netdisco has nothing to do with dancing and everything to do with network discovery.
Netdisco sees all and inventories all: device model, operating system, IP addresses, MAC addresses, wireless access point locator, and individual switch ports. Computers, printers, switches, routers, and hubs can't hide from Netdisco. SNMP-enabled devices will even report configuration information.
Netdisco stores all of the data it collects in a PostgreSQL database, which is searchable by almost any criteria to get information on a particular device: location, description, DNS name, IP address, vendor name, model number, OS version, and so forth. It's almost worth it just for its ability to find duplex mismatches and rogue wireless access points, two items that cause great vexation for network admins. You can see a demo in action at Netdisco.org/demo.
After it's installed and configured, Netdisco is a breeze. The Web interface is useful and easy to navigate. However, installing it can cause premature hair loss, as it is not an easy job. Hopefully, the next release will improve the installation, or your favorite Linux distribution will package it for you.
Downloads, documentation, and a large helpful user community are found at Netdisco.org.