Expanding on Visio's basic autodiscovery and layout feature, Fluke Networks' Network Inspector builds a detailed database of the devices in a MAC broadcast domain and then lets you slice and dice the data through reports and Visio diagrams. Most significantly, Network Inspector is the only product we've seen that not only discovers which devices are on your network but also reveals how they are interconnected. To do this Network Inspector queries the MAC address table in the Bridge MIB and uses that data to determine how switches are interconnected and how workstations are connected to switches. Anyone who's ever spent an afternoon in a wiring closet tracing cables to figure out which port on which hub the vice president with the flaky connection is plugged into will agree that this data can be incredibly valuable. We expect some admins will even discover a substantial number of unused switch ports, eliminating the need to buy an additional switch and helping Network Inspector pay for itself.

Once the data is collected, we could generate reports and Visio diagrams showing server and router connections, switch interconnections, and IP or IPX device inventory. Like its standard router equivalent, Fluke's unique switch traceroute feature shows the route packets take traveling from one device to another. This is the cool ultimate expression of deep Layer 2 knowledge.

Network Inspector divides the data-collection process into a separate agent program, letting us install multiple agents distributed throughout our network and manage them from a single console. Network Designer was built to store each broadcast domain's data in a separate ODBC database, so there isn't a mechanism to build reports of a whole enterprise network.

Network Inspector (screen view) Click here to enlarge

Network Inspector doesn't stop at creating network documentation. It can also generate reports and send alerts via e-mail on configuration errors like bad subnet masks, changes to addresses or services on stations, and interface collision and error rates. With the optional Switch Inspector we gained the ability to monitor a switch's RMON functions and graph port utilization and collision rates for a 24-hour period.

Unfortunately, Network Inspector's reliance on working at Layer 2 of the OSI model means it reaches its full potential only on networks that don't use features such as VLANs and vendor-specific switch stacking, in which you have a stack of switches with a single IP address for management. Our test network, which used multiple Cisco 3500XL switches, stacked with only the "mother" switch having an IP address in a dedicated management VLAN. As a result, several of Network Inspector's features, including switch traceroute, weren't fully functional until we reconfigured the switches in a more conventional mode. Also on the downside, Network Inspector is relatively expensive, and Fluke has joined the ranks of vendors that believe help files are a replacement for manuals. Still, Network Inspector is the only automated way we know of to collect deep-down Layer 1 and 2 details of your network.

Network Inspector Network Monitoring Software, starts at $995 for 250-node discovery and one console license; LAN MapShot Network Diagramming Software, $499. Available: Now. Fluke Networks, (800) 283-5853, (425) 446-4519; fax (425) 446-5116. www.flukenetworks.com