Network tools

Many tools are available to determine latency, jitter, and packet loss on IP networks. Tools fall into several categories: reactive and proactive, passive and active. Passive tools are reactive and "sniff" the network to display or capture existing (real) traffic. Active tools inject packets into the network to test network characteristics (proactive) or to stress test specific network elements. Modeling tools are also proactive because they model future "what-if" scenarios without inducing a load on the network. A partial list of these commercial tools follows.

These tools are available for purchase through their respective vendors and have been found to be very useful for diagnoses, analysis, modeling, and monitoring networks and VoIP conversations. None of these tools are specifically endorsed or explicitly warranted by Avaya Inc. They merely represents a starting list of tools that fit the active, passive, and modeling categories that are needed to properly assess networks and network products. Other tools exist that may be a better fit for your organization.

• Finisar-Systems THG (formerly Shomiti Systems Explorer). This hardware-based tool measures delay, cell loss and jitter at wire speeds from 10Mbps to 1000 Mbps and provides a seven-layer decoding of captured frames. Because it has a dedicated server for sensing traffic, results are more accurate than with software-based tools. It normally acts in passive mode by "sniffing" traffic. It can also be an active device by injecting packets into the network. Information is available at http://www.finisar.com.
• Ixia 100 QoS Performance Tester (also the 400 and 1600). This hardware-based tool is both a traffic generator and performance analyzer. It measures delay, jitter and cell loss from 10 to 1000 Mbps. It is scalable to higher speeds as it can use OC3 through OC192 for generating traffic. The results are available for pre- and post-processing by the user and the software code is open for users to customize. Information is available at http://www.ixiacom.com.
• NetIQ Chariot. This software tool allows customized traffic generation controlled from a server between two PC endpoints. Traffic is created by selecting pre-made scripts or writing your own and represents data from the application level. Lower level (OSI layers 4, 3 and 2) traffic is also available to configure and send. Information is available at http://www.NetIQ.com.
• Fluke� Enterprise LANmeter�. This all-purpose hardware instrument can be used as a traffic generator and diagnostic tool, or to check Category 3 and 5 cables, simulate an endpoint, etc. It will not test fiber (yet), but it is very portable and capable of troubleshooting a LAN. Results can be viewed from a Web browser and an online database option is available. Information is available at http://www.fluke.com.
• OPNET� IT DecisionGuru and Modeler. OPNET produces "Cadillac" software products that will discover network elements and model the behavior of a LAN. This predictive feature is a good way to test changes to the network before implementing the actual hardware. The accuracy of results to real world experience ranges from 80 to 95 percent, which is higher than most mathematical only models because each element performs like the physical unit it represents. The code is partially open and users can create new objects or modify existing ones. This is a good proactive tool for network analysis. Information is available at http://www.opnet.com.
• Network Associates� Sniffer� tools. These industry-standard frame-capturing tools are very handy for examining and verifying content of OSI model layers 2, 3 and 4. They cannot measure latency or cell loss. They are portable and also analyze long-term network trends. Information is found at http://www.nai.com.