### TechNote

Number: 03201-04
Date: October 1994

### What is SNMP?

An internet is a set of connected networks that act as a co-ordinated whole. The chief advantage of an internet is that it provides universal interconnection while allowing individual groups to use whatever network hardware is best suited to their needs. Internet managers need some form of software to help them monitor and control the variety of hardware and software that is on the internet.

SNMP, which stands for Simple Network Monitoring Protocol, is an internet management protocol, by which communications devices are monitored and controlled by network management systems. It provides a protocol for sending and receiving management information that a management program can use as a basis for its functionality across the internet.

SNMP performs operations by manipulating the Management Information Base (MIB), which is a database of information about managed objects. All management-relevant data can be defined in object-oriented terms as a set of object, relations, and operations onto and between objects. The MIB is a collection of these objects.

All the managed objects are organized in a hierarchical structure called the 'Management Tree'. Each branch in the SNMP tree is assigned a specific number. When you concatenate all of the numbers of the branches leading to a particular object in the tree together, the decimal notation, known as the Object Identifier, represents a unique path in the tree. Each object defined in the MIB has a unique Object Identifier associated with it.

Only four operations are available to the protocol:

- Get retrieves specific management information
- Get next retrieve the next piece of management information by traversing the MIB
- Set manipulate management information
- Trap report extraordinary events

It is through the sending, receiving, and logging of many of these simple transactions that network management systems using SNMP accomplish their tasks.