SNMP is part of the TCP/IP protocol stack. It is an application-layer protocol (see section on OSI reference model). It uses the services of the UDP transport layer. UDP is the little brother of the TCP transport protocol, and is used to send simple messages across a TCP/IP network. Originally designed to use the IP network protocol, it is also commonly ported to IPX, for use with Novell networks. SNMP is a simple protocol that generates minimal traffic across the network. The rest of this section will concentrate on SNMP.

What does it do?
SNMP works in conjunction with a database on each managed device called a MIB. The MIB contains all the parameters that can be viewed, or altered for the device in question. The most common MIB specification in use today is MIB-II. This is a second generation specification, which improved on the original by adding support for more network devices, identification of media types, and standards for building proprietary extensions of the basic MIB.

SNMP inteacts with the MIB by a set of 5 messages. There are three commands that can be issued by the manager. These are a GetRequest, which queries the device about the status of a MIB variable, the GetNextRequest, which requests the status of multiple variables, and the SetRequest, which directs a change to a variable.

The device agent originates two types of messages. These are a GetResponse, which acknowledges any request from the manager, and a Trap, which is a non-solicited message to the manager in response to some event, such as a device failure or other problem.

How is it used?
SNMP and CMIP are the protocols used to exchange data and control information between the network management station and the managed devices. Of the two, SNMP is by far the most common. These protocols interact with the lower level protocols used to transmit data across the network. The standards for these protocols provide a common set of specifications that allows devices from different manufacturers to all speak a common language. This simplifies the network management process, and allows one network management system to interact with a wide range of network devices.

Where do I get more information?
Contact your local CBV Office.