Network Monitoring

The Simple Network Management Protocol (SNMP) and Remote Monitoring (RMON) protocol are powerful tools that can be used to manage a medium to large network. In a small LAN, such as in a home office, these capabilities are not needed. If a device such as a cable/DSL modem or router is not working, you will probably be able to determine that quickly. This applies also to your printer (it has run out of toner or ink), and your computer(s) (it hangs or crashes). However, when a network is spread out over a large geographical area, or when a large number of network devices and computers are on the network, these two protocols can be used with management consoles to help you diagnose problems remotely and gather statistical information about your network. SNMP and RMON also can help you spot trouble before it becomes a real problem.

SNMP basically collects data about computers and other devices on the network, and is used with a management console application to provide a central reporting station. RMON is similar to SNMP but supports additional features, especially on the remote devices. By choosing a good management station application, you can set up thresholds for certain events (such as network traffic, errors, and other statistical information) so that automatic alerts are issued to warn you when something is amiss.

SNMP and RMON are covered in greater detail in Chapter 53, "Network Testing and Analysis Tools." If you manage a large network, the central network management application that you use (such as HP OpenView or IBM's Tivoli suite of products) uses these protocols to obtain information from networked devices or, in the case of RMON, to set variables in the Management Information Base (MIB) of these devices.