SNMP Protocol

SNMP Stands for Simple Network Management Protocol.

It is an Application Layer protocol (Layer 7 protocol) defined by the Internet Architecture Board (IAB) in RFC1157 for exchanging management information between network devices.

SNMP provides a common language for network devices to switch management information with single as well as multivendor environments in a local area network (LAN) or wide area network(WAN).

There are three basic versions of SNMP. 

SNMP v1
SNMP v2
SNMP v3

SNMP Flow between Manager and Devices with Agent configuration.

SNMP Components:

1. SNMP Manager.
2. Managed Devices
3. SNMP Agent
4. MIB.

SNMP MANAGER : The SNMP manager job is to acquire with SNMP requests, information about devices connected to the network. Gathered information are then processed and displayed in tables, graphs, gauges, histograms, for an easier interpretation by Monitoring User.

SNMP Manager’s key functions

• Queries agents
• Gets responses from agents
• Sets variables in agents
• Acknowledges asynchronous events from agents

MANAGED DEVICE AND AGENT : The agent is a mixture of software & hardware or only software and is located in the device.

SNMP Agent’s key functions :

• Collects management information about its local environment
• Stores and retrieves management information as defined in the MIB.
• Signals an event to the manager.
• Acts as a proxy for some non–SNMP manageable network node.

SNMP MIB Browser: SNMP MIB Browser is a complete tool for monitoring SNMP enabled devices and servers.

MIB Browser's Key functions :

To view, configure and parse SNMP traps.
User can view multiple MIB modules and perform GET, GETNEXT and SET SNMP operations.

Basic commands of SNMP:

GET: The GET operation is a request sent by the manager to the managed device. It is performed to retrieve one or more values from the managed device.

GET NEXT: This operation is similar to the GET. The significant difference is that the GET NEXT operation retrieves the value of the next OID in the MIB tree.

GET BULK: The GETBULK operation is used to retrieve voluminous data from large MIB table.

SET: This operation is used by the managers to modify or assign the value of the Managed device.

TRAPS: Unlike the above commands which are initiated from the SNMP Manager, TRAPS are initiated by the Agents. It is a signal to the SNMP Manager by the Agent on the occurrence of an event.

INFORM: This command is similar to the TRAP initiated by the Agent, additionally INFORM includes confirmation from the SNMP manager on receiving the message.

RESPONSE: It is the command used to carry back the value(s) or signal of actions directed by the SNMP Manager.