Monitoring Errors

There are many tools you can use to monitor errors on the network. A network analyzerfor example, Network Sniffer from Network Generaldisplays information about frames that contain errors, including runts, CRC, and alignment errors. Some software-based applications, such as the Network Monitor tool included in Windows NT Server or Microsoft's System Management Server, enable you to view statistics about frames dropped, CRC errors, and broadcasts. Simpler handheld tools also might provide functionality that enables you to detect when these errors are occurring.

For a network that requires centralized management and control, an SNMP management console application, using RMON, can be used both to monitor the network for Ethernet errors and to set up alerts that trigger notifications so that you can become aware of problems immediately. The history group of RMON objects allows you to record error counts over a period of time and use them for later analysis to assist in troubleshooting.

You can find more information about SNMP, RMON, and network monitoring tools in Chapter 48, "Strategies for Troubleshooting Network Problems," and Chapter 49, "Network Testing and Analysis Tools." For more specific information on how to isolate Ethernet problems, see the chapters devoted to network cards, cables, hubs, switches, and routers.

Depending on the vendor, many internetworking devicessuch as routers and intelligent hubsare equipped with management software that can be tapped to display error statistics when you do not need a more extensive application (such as a management console). Checking statistical information on a regular basis and keeping a log of it is a good idea. When you keep track of error conditions on a regular basis, you can begin to solve problems more quickly because you can determine whether the current situation matches a previous problem.