ISPPlanet Network Management System Series - SNMP ToolChest

Network Discovery

We started our evaluation with DiscoverPlus (right), a tool that finds SNMPv1-capable devices on class B or C subnets. DiscoverPlus uses subnet address(es) supplied by file or GUI to kick off a sequential three-phase scan of each subnet. In the first phase, every address in the subnet is pinged—and the GUI becomes largely unresponsive to user input (like Stop).During the second phase, an SNMP GET is sent to every device that responded to pings—only devices that supply all requested system objects are "found". An optional third phase collects MAC addresses from found devices. A progress bar and status window describe what's happening throughout this somewhat lengthy process—we found four minutes per class C subnet typical.

Discovery results are viewed through the GUI, stored in a "database" textfile, and recorded in per-subnet HTML reports. Subsequent discoveries on the same day overwrite prior results, but results from different days can be compared (left) to detect network changes. Search IP and Search MAC functions make it easy to locate a particular device in the latest results, handy for networks with many subnets. A Find MIB function can search results for devices that support a given management information base.

We bumped into a few bugs on during our initial Network Discovery test drive—in fact, we ran into at least one bug in every ToolChest application. But the SNMP ToolChest Company responded to all problems within a few hours, supplying a quick fix in nearly every case. Silver Edition apps are a recent port of selected Gold Edition apps, and it seems that we bumped into porting oversights easily remedied by Tcl script updates. We were highly impressed by this vendor's responsiveness, but disappointed by apparently inadequate pre-release testing. The longer-lived Gold Edition is presumably more mature, as we'd expect the Silver Edition to become with time.

With bug fixes applied, we had little trouble discovering our sparsely-populated three-subnet test network. There are many reasons why a device might not respond to SNMP queries (for example, invalid community string). We'd like an option to identify every ping-able device in discovery results, providing the information needed to track down offending devices. Since several other tools accept a device list as input, it would be nice for DiscoveryPlus to produce a suitably-formatted "all found devices" file.

Go to Part 3: Device Browse & Query / Device Control