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HP Takes The Lead In The Fast Ethernet Analyzer Race

By Peter Morrissey A network analyzer can be an invaluable tool given today's increasingly complex intranet and client-server environments. A good analyzer can help you sort out the most difficult problems involving the network infrastructure and the applications that it supports. We tested six Fast Ethernet analyzers in Network Computing's

Syracuse University lab and found that while their overall ratings were close (see Report Card, below), they each offer distinct benefits. Hewlett-Packard Co.'s HP Internet Advisor WAN-T1 and Fast Ethernet Undercradle, which took top honors, and Network General Corp.'s Fast Ethernet Sniffer Network Analyzer, a close second, were the only products with sophisticated diagnostic aids. Although the Fast Ethernet Sniffer was a little better in this area than th e Internet Advisor, it was hurt by its lack of full-duplex capabilities and its inability to decode or monitor virtual LANs (VLANs).

To view the Report card.
Shomiti Systems' Surveyor and Explorer combination was also a contender because of its ability to provide detailed network monitoring data and full-duplex connectivity at a high rate of performance. We also tested Wandel & Goltermann's DominoFastEthernet DA-350 and Cinco Networks' NetXRayPro/100S and NetXRay Pro/100D.

More Than Reading the Screen The HP and Network General products try to accelerate the process of solving network conundrums by automatically presenting diagnoses of possible problems. Both vendors use the word expert to describe this feature in the sense that a knowledge base of expertise is applied to the network traffic, examining frames up through the appli cation level for events that could signal problems. This information, particularly with retransmits and slow server diagnoses, involves keeping track of previously transmitted packets and can be useful in highlighting and determining the cause of poor performance.

However, neither HP nor Network General can give novice network engineers the ability to troubleshoot difficult network problems. In some cases, the diagnoses will be false alarms or misleading. In most other cases, the diagnoses require a fairly high level of knowledge and experience to interpret.

Most of the time, you just have to jump in and sort through packets one at a time. The ideal time to start doing this is before problems occur. Use an analyzer to help you understand how network protocols work and to determine what is "normal" for your particular network. Sifting through individual packets requires a fair amount of expertise and patience, but the presentation of the information can ease some of the pain and save time by making the decodes clear and readable. Network General's Sniffer excels in this area, and Wandel & Goltermann's Domino is even better because it can view multiple decodes.

Troubleshooting switched networks with full-duplex connections and VLANs presents a new set of challenges (see "Troubleshooting Next-Generation Architectures," September 1, page 126). One of the reasons Network General's Sniffer did not do better in our rankings was it could not tap directly into full-duplex connections. It was also the only one that could not decode Cisco Systems' Interswitch Link (ISL) VLAN protocol, which identifies frames from mixed VLANs that traverse a common trunk between switches. When we plugged Sniffer into one of the links between two Cisco 5000s, it was not able to decode any of the frames on the link.

The HP and Shomiti Systems products can decode and monitor the usage of each VLAN on a trunk. For example, they can summarize each VLAN by name along with the relative utilization of each VLAN on the link.

To download an Adobe Acrobat .pdf format version of the Fast Ethernet Analyzers features charts, click here.