Overview of Simple Network Management Protocol - SNMP

- The Simple Network Management Protocol (SNMP) is an application layer protocol that facilitates the exchange of management information between network devices.
- It is part of the Transmission Control Protocol/Internet Protocol (TCP/IP) protocol suite.
- SNMP enables network administrators to manage network performance, find and solve network problems, and plan for network growth.
- SNMP is a popular protocol for network management.
- SNMP can collect information such as a server’s CPU level, server chassis Temperature etc.
- SNMP is the protocol that allows an SNMP manager (the controller) to control an SNMP agent (the controlee) by exchanging SNMP messages.
- The SNMP protocol was designed to provide a "simple" method of centralizing the management of TCP/IP-based networks.

SNMP Basic Components

SNMP consists of three key components: managed devices, agents, and network-- management systems (NMSs).
- A managed device is a network node that contains an SNMP agent and that resides on a managed network.
- An agent is a network-management software module that resides in a managed device. An agent has local knowledge of management information and translates that information into a form compatible with SNMP.
- An NMS executes applications that monitor and control managed devices.

SNMP Commands

- The read command is used by an NMS to monitor managed devices. The NMS examines different variables that are maintained by managed devices.
- The write command is used by an NMS to control managed devices. The NMS changes the values of variables stored within managed devices.
- The trap command is used by managed devices to asynchronously report events to the NMS. When certain types of events occur, a managed device sends a trap to the NMS.

SNMP itself does not define which information (which variables) a managed system should offer. Rather, SNMP uses an extensible design, where the available information is defined by management information bases (MIBs). MIBs describe the structure of the management data of a device subsystem; they use a hierarchical namespace containing object identifiers (OID). Each OID identifies a variable that can be read or set via SNMP.