Your company's transactions, queries, documents, intranet data and files are its lifeblood, and your network's connections are the arteries that carry that blood. Keeping those connections healthy is more than just prudent. It's critical. No company wants to see its network in intensive care - or the morgue.

Many vendors offer monitoring software, devices or combinations of both to help you maintain WAN links at the peak level. These vendors promise their tools will alert you when outages occur, pinpoint the root cause of the outage and help you reestablish communications immediately. They claim to produce useful reports showing utilization trends, outage statistics, service-level agreement (SLA) compliance and other information. Vendors say the tools are easy to use, scale well, integrate with network management systems, handle any and all protocols, and have lots of additional features, such as the ability to prioritize network data based on quality-of-service parameters you provide.

To find the best WAN monitoring tool for your network, we invited vendors to submit their products to our lab. We tested Network Instruments' Observer 8.3 software and rack-mountable WAN Probe with a pair of T-1/E-1 analyzer taps; Neon Software's CyberGauge 5.0 software; Adtran's IQ 710 with traffic shaping and N-Form 1.4 monitoring software; Visual Networks' Visual UpTime 7.1 and Analysis Service Elements (ASE - DSU/CSUs augmented with link monitoring capabilities); Concord's eHealth 5.6 software; and Allot's WiseWAN 401 Network Application Priority Switches (link monitoring, shaping and controlling devices) and WiseWAN Network Application 5.2 Enterprise software.

Visual UpTime was the best product for keeping WAN links up and running smoothly and wins our World Class award. Although it only works with Visual Networks' DSU/CSU devices, Visual UpTime's precise and accurate monitoring ability is unsurpassed. Its many reports are practical and well designed, the user interface is intuitive and responsive, and it scales well.

For heterogeneous networks, Concord's eHealth is a World Class winner for its superior reports and amazing breadth of recognized and supported devices.

All the products did well in our tests. They proved themselves worthy, reliable tools for monitoring critical WAN links.

Hardware vendors leverage their sales by bundling or offering software that works only with their devices. In contrast, software vendors work hard to support as many devices as possible. This can pose a dilemma for companies planning to expand or upgrade an existing network.

Not surprisingly, we saw the best and most-detailed monitoring of our WAN links from products that merged a vendor's software with its hardware devices. Visual UpTime gathered statistics from and sent control commands to Visual Networks' own DSU/CSUs; Adtran's N-Form software provided WAN monitoring for the company's IQ 710 DSU/CSUs; and the WiseWAN Network Application Enterprise software worked with the WiseWAN 401 monitoring and traffic-shaping devices. Similarly, Network Instruments' Observer WAN monitoring relied on the presence of a WAN Probe located at the other end of a monitored link.

On the other hand, Concord's eHealth and Neon Software's CyberGauge gave us support for a range of network devices, but didn't monitor as closely nor deliver the level of detail that, for example, Visual UpTime did.