Simple Network Management Protocol, SNMP - Part 1

Simple Network Management Protocol or shorter SNMP is protocol for managing devices on IP networks. Its predecessor was SGMP (Simple Gateway Management Protocol) and was intended to be replaced by a solution based on the CMIS/CMIP (Common Management Information Service/Protocol) architecture.

SNMP exposes management data in the form of variables on the managed systems, which describe the system configuration. These variables can then be queried (and sometimes set) by managing applications. SNMP is working on agent-manager model which consists of an SNMP agent, SNMP manager, database with management information and managed device.

The SNMP manager and agent use MIB and very few commands to exchange information. The SNMP MIB is organized in tree structure with branches and leaves. Every leaf  is variable such as description, status, etc... There is a long numeric representation tag or object identifier (OID) which distinguishes each variable in MIB.

There are five messages that SNMP uses for communication between manager and agent; GET, GET-NEXT, GET-RESPONSE, SET, and TRAP. SNMP manager can request information with GET and GET-NEXT messages. If agent receives one of this two messages, he answers with GET-RESPONSE message. SET message allows SNMP manager to set certain value for some variable, and in the end TRAP message proactively informs SNMP manager that important event has occurred and needs extra attention.

In next part of SNMP tutorial, we will talk about MIB...