Methods to Interrogate the Network

Just as the early explorers had compasses, sextants, and the stars to guide them and assist in mapping new worlds, network designers need to collect tools and develop methods for creating their own maps.The explorer's advantage is that the terrain of these new worlds does not change, while network maps are often obsolete within hours of being created. Because of the rapid pace of change in networking, updating network diagrams could very well be a frequent activity. Therefore, honing your tools and methods will make your job easier and save you valuable time.

Auto-discovery tools actively gather information on new and existing network nodes and the health of the network, and can produce diagrams and reports on the fly.These enterprise systems management tools are expensive, but on a large network their utility can quickly justify the costs, especially if they can reduce the number of people needed to manage the network or can be used to quickly diagnose and resolve costly outages. Diagramming software is also bundled in network-discovery tools to quickly generate diagrams.

Sniffers and protocol analyzers discover the protocols in use and the hosts that are using them. They can also isolate individual links and measure the bandwidth being used for individual services, such as DNS, HTTP, FTP, RTSP, and Quake2. Bandwidth consumption is especially important in a distributed network in which slow WAN links can become bottlenecks for replication.

You can also employ less scientific methods for gathering information. For information on the technical details of your WAN links, the first place you should check is with your telecommunications carrier(s). They should quickly be able to supply information on the links they are providing to you. Second, if you are one of those types who have to see it to believe it, then site inspections might be in order. Taking copious notes, capturing screenshots, and even taking pictures with a digital camera can ensure that information you received from others or through network discovery tools are complete and accurate. Finally, you can produce some rudimentary network performance statistics by capturing response times and other metrics through basic TCP/IP utilities such as tracert and ping. Enterprise systems management tools, if available, can be used to produce more sophisticated measurements.

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