A tool for identifying, analyzing, and diagnosing communications network problems. Analyzers enable technicians, engineers, and managers to test the performance of the network to ensure that the systems and the network function according to specifications. LAN managers, for example, use protocol analyzers to identify protocols in use, to identify protocol mismatches and other performance faults, to perform network maintenance and troubleshooting, and to plan network upgrades and expansions. See also LAN, network, and protocol.