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  Wandel & Goltermann's High-Speed Analyzers Tops in Tests February 8, 1999 | |
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By J. Scott Haugdahl When it comes to solving critical networking problems, protocol analyzers are the tools of choice for many networking professionals. As networks evolve to incorporate newer technologies, such as ATM and Gigabit Ethernet, it takes state-of-the-art analyzer technology to keep up. DOS- and Windows-based protocol analyzers that use off-the-shelf network adapters just won't cut it in these environments. For this review, we invited ATM and Gigabit Ethernet protocol analyzer vendors to submit their wares for testing. We ended up with ATM analyzers from GN Nettest, Hewlett-Packard Co., Network Associates, and Wandel & Goltermann Technologies. DominoATM from Wandel & Goltermann beat out the competition in the ATM category by a hair, due to the quality and sophistication of the decodes it provides for both the high-level and lower layers of the ATM stack.
Unfortunately, Wandel & Goltermann was the only vendor to submit its product for our Gigabit Ethernet analyzer tests. Although it is a bit pricey at $41,000, DominoGigabit is very stable with excellent performance in capturing packets at gigabit speeds. We had hoped to test Gigabit Ethernet protocol analyzers from both HP and Network Associates but things didn't work out. HP is grappling with some performance problems it says are related to the Intel Gigabit Ethernet MAC (Media Access Control) chip used in its Internet Advisor gigabit analyzer. Network Associates declined to participate, saying its Gigabit Sniffer is in the midst of a major software transition from DOS to Windows. Our tests for both the ATM analyzers and the sole Gigabit Ethernet analyzer entry focused on performance, ease of use, quality of decodes and monitoring capabilities. Common Lapses While our tests showed that each product has its strong points, in general all the products are missing several key features. For example, all of the ATM analyzers we tested lack expert systems support. For Gigabit Ethernet, you can buy the optional Mentor expert system for DominoGigabit to analyze captured data only. But real-time expert analysis is not available. To provide real-time expert analysis at speeds greater than 100 Mbps, you need an incredible amount of horsepower. Even when working with networks faster than 10 Mbps, expert systems often lag behind in their analysis. Now imagine having to analyze a worst-case burst in excess of 1 million packets in less than one second from a gigabit backbone. The array of options in ATM also makes it difficult to provide expert analysis. Unlike Ethernet, which has only a few simple frame formats depending on the DLC (Data Link Control)-layer encapsulation, ATM has several cell formats, adaptation layers and ways to use them. IP, for example, can be sent three or four different ways over AAL 5 (ATM Adaptation Layer 5). High-speed protocol analyzers only decode the various ATM layer types and cell information, and, where applicable, reassemble the cells into frames. Now the vendors need to develop tools that can provide expert analysis for ATM-specific events.
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