All variety of the means applied to monitoring and analysis of computer networks, it is possible to divide into some large classes:

The centralized program systems which are collected by data about a condition of units and communication devices of a network, and also data about the traffic circulating in a network. These systems not only carry out monitoring and the analysis of a network, but also in an automatic or semi-automatic mode of a network management - inclusion and switching-off of device ports, change of address tables parameters of bridges, switches and routers can serve. As Examples of control systems - popular systems HPOpenView, SunNetManager, IBMNetView.

Control facilities system often carry out the functions similar to functions of control systems. But in relation to other objects. In the first case object of management is program and hardware maintenance of computer networks, and in the second - the communication equipment. At the same time, some functions of these kinds of control systems can be duplicated. For example, control facilities system can carry out the elementary analysis of the network traffic.

These systems are carried out in the form of the hardware-software modules established in the communication equipment. Also in the form of the program modules which have been built in operational systems. They carry out functions of diagnostics and management only one device, and in it their basic difference from the centralized control systems. An example of this class module means of management as concentrator Distributed 5000, realizing auto-functions can serve segmentation of malfunction ports at detection, attributings of ports to internal segments of the concentrator and some other. As a rule, the built in modules of management a role of the SNMP-agents, delivering data about a condition of the device for control systems "in combination" carry out.

Represent program or hardware-software systems which are limited unlike control systems only to functions of monitoring and the analysis of the traffic in networks. The good analyzer of protocols can grasp and decode packages of a protocols plenty applied in networks - some tens are usual. Analyzers of protocols allow to establish some logic conditions for capture of separate packages and carry out full decoding the grasped packages, that is show in the form convenient for the expert an enclosure of protocol packages of different levels each other with decoding the maintenance of separate fields of each package.

This kind of systems accumulates human knowledge of revealing the reasons of networks abnormal work and possible ways of a network reduction in an efficient condition. Expert systems are realized in the form of separate subsystems of various means of monitoring and the analysis of networks. For exemple - network control systems, protocol analyzers, network analyzers. The elementary variant of expert system is the context-dependent help-system. More complex expert systems represent the so-called knowledge bases possessing elements of an artificial intellect. An example of such system is the expert system which has been built in control system Spectrum of company Cabletron.

Last years there was a necessity of the inexpensive portable devices development, combining functions of several devices: protocol analyzers, cable scanners and, even, some opportunities ON network managements. As an example of such devices it is possible to result "Compas" by Microtest Inc. or "LANMeter" by Fluke Corp.