Simple Network Management Protocol (SNMP) is an Internet-standard protocol for managing devices on IP networks. Devices that typically support SNMP include routers, switches, servers, workstations, printers, modem racks, and more. It is used mostly in network management systems to monitor network-attached devices for conditions that warrant administrative attention. SNMP is a component of the Internet Protocol Suite as defined by the Internet Engineering Task Force (IETF). It consists of a set of standards for network management, including an application layer protocol, a database schema, and a set of data objects. SNMP exposes management data in the form of variables on the managed systems, which describe the system configuration. These variables are usually called OIDs. They can then be queried (and sometimes set) by managing applications. The OIDs have a tree hirerchical structure and are described in Management Information Base (MIB) files. Each MIB file contains only a part of the tree.
Figure 1 SNMP OID tree
SNMP OID tree could be manipulated by a set of atomic queries.
- SNMP GET - allows us obtaining the value of s specific OID.
- SNMP WALK - use takes advantage of the hierarchical tree structure and allows the management application to obtain the value of a portion of the tree. If a WALK is executed against the system table it will obtain the values of sysDescr, sysObjectID, sysUpTime, sysContact, sysName, sysLocation and others.
SNMP SET. As the name suggests the set is used for changing the value of specific SNMP OID.
iTransformer supports SNMP version 1 and version 2c. Version 3 is still not supported.