Last time, we described an exciting new category of IP troubleshooting called "route analytics," which helps you quickly determine root causes of IP-layer routing faults. The two primary players, Packet Design and Ipsum Networks, seem to have hit on a biggee - making IP networks work better in a pretty simple fashion.

In fact, Ipsum's  vice president of marketing Frank Hayes calls his company's products "lobotomized routers that will establish an adjacency in an area."

What he means is that his company's products connect to routers but only in listening mode, tapping into routing protocol information exchanges to track packet flows across enterprise boundary routers. The products detect paths that application traffic would travel and alert network operators if anything should cause that data-path availability to change.

Products from both companies view the Layer 3 logical path topology, which is continually changing, on an ongoing, real-time basis. By contrast, network-layer analysis systems today tend to take baseline snapshots of Layer 3 topologies, at best, a few times a day, because of the huge network overhead that would be incurred by transferring huge routing tables any more often. Static snapshots are more useful for planning than real-time troubleshooting.

Let's compare the basics of the two route analytics products mentioned, which are functionally very similar:

* Packet Design, Route Explorer 1.5

Routing protocols supported: Open Shortest Path First (OSPF) and Intermediate System-to-Intermediate System now; BGP and Cisco Enhanced Interior Gateway Routing Protocol (EIGRP) scheduled for later this year.

Form factor: 2-rack-unit (RU) appliance listens across any number of domains.

List pricing: $35,000 for a 50-router network to $75,000 for a network of 250 or more routers

* Ipsum Networks, Route Dynamics Multi-Area Path (MAP)/IP Listener Appliances

Routing protocols supported: OSPF now. BGP scheduled for late 2003 or early 2004; IS-IS scheduled for first-half 2004.

Form factor: Linux-based 2RU MAP in core routed network communicates to a 1RU IP probe in each routed area. Each physical probe has six ports and can support multiple logical listeners, so one appliance can listen to six local routed areas. Additional physical probes are required in remote locations.

List pricing: $50,000 for one MAP and one probe with one logical listener. As you activate additional listeners, you pay a license fee.

Steve Taylor is president of Distributed Networking Associates and publisher/editor-in-chief of Webtorials. Jim Metzler is vice president of Ashton, Metzler & Associates.