Monday, April 8, 2002		Article

During designing of either Local or Wide Area Network (LAN/WAN), one of the main issues that arise is to provide stable network system while keeping a tab on costs. Is it possible?

Definitely yes, if you have adopted Network Management System (NMS). NMS is based on Simple Network Management Protocol (SNMP) through which any type of network can be managed or controlled. SNMP, a part of Transmission Control Protocol/Internet Protocol (TCP/IP) suite, is management software that can control and manage devices on any connected network. The SNMP manages network performance, finds and solves network problems; monitors printers queues and install software on the network.

SNMP can manage all these using two main elements - agent and the manager. This is how it works:

SNMP manager is the software that runs in the monitoring station of the network and its role is to contact different agents running in the network. SNMP agent is a program running in each of the monitored or managed nodes of the network. In other words, agent is the device being managed. It provides an interface to all items of their configuration. These items are stored in a data structure called management information base (MIB). So MIB is information that can be accessed using SNMP. MIB is ASCII file that describes the device information that can be obtained from agent. Each item of information in MIB is called "object." Data is passed from such SNMP agents to the management workstation console used to oversee the network. .

Network devices can be monitored and controlled using four basic SNMP commands - read, write, trap, and traversal operations. Read command is used to monitor managed devices. Using this command, system running manager software i.e. management station examines different variables (database) that are maintained by managed devices (agent). However, write command is used to control managed devices. Using this, management station can change the values of variables stored within managed devices.

Trap command is a special command in SNMP command set used by managed devices i.e. agent. Using trap agent can interrupt management station in case of any event or error, shutdown occurs. While traversal operations are used by the management system to determine which variables managed device supports and to sequentially gather information in variable tables, such as a routing table etc.

Almost all manufacturers have already implemented versions of SNMP agents in their devices - routers, hubs, switches and operating systems. If a manufacturer wants to add some new commands to a device like router, he must add the appropriate variables to its database.