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SNMP-Simple Network Management Protocol

Many of my friends asked me to write on SNMP since they didn’t get much information about it from the Internet. So this post is for my friends who want to read about Simple Network Management Protocol (from now on SNMP) .

The SNMP is a framework for managing devices in an Internet using the TCP/IP protocol suite. It provides a set of fundamental operations for monitoring and maintaining the Internet.


SNMP uses the concept of manager and agent. That is, a manager. usually a host,controls and monitors a set of agents, usually routers.

SNMP is an application-level protocol in which a few manager stations control a set of agents. The protocol is designed at application level so that it can monitor devices made by different manufacturers and installed on different physical networks. In other words, SNMP frees management tasks from both the physical characteristics of managed devices and the underlying network technology. It can be used in heterogeneous internet made of different LANs & WANs connected by routers made by different manufacturers.

Managers and Agents

A management station, called a Manager, is a host that runs the SNMP client program. A managed station, called the Agent, is a router (or a host) that runs the SNMP server program. Management is achieved through simple interaction between manager and an agent.

The agent keeps performance information in a database. The manager has access to the values in the database. The manager can also make the router perform certain actions.

Agents can also contribute to management process. The server program running on the agent can check the environment and, if it notices something unusual, it can send a warning message (called a TRAP) to the manager.

In other words. management with SNMP is based on 3 basic ideas:

  1. A manager checks an agent by requesting information that reflects the behavior of the agent.
  2. A manager forces an agent to perform a task by resetting values in the agent database.
  3. An agent contributed to the management process by warning the manager of an unusual situation.

Management Components:

To do  management tasks, SNMP uses to other protocols

  • Structure of Management Information (SMI)
  • Management Information Base (MIB)

In other words, management of Internet is done through the cooperation of 3 protocols: SNMP, SMI, MIB

SMI & MIB discussed in above posts.

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