Simple Network Management Protocol (SNMP)
SNMP is one of the more common management protocols you will find on an enterprise network. It is the default protocol used for monitoring network (and other) infrastructure. SNMP relies on a database named a ‘management information base’ (MIB), which provides variables for system status and configuration.
SNMP has gone through a number of reiterations, SNMPv1, v2c, v3. Each release improves security, stability, performance.
SNMP uses one or more ‘managers’ which monitor the group of clients. Each client has an agent which is responsible for reporting information back to the manager via SNMP. The manager operates a “Network Management Station” which monitors and controls managed clients.
The client, also known as a managed device, provides the interface for SNMP communication. This could be in the form of read only, or read write access. Within the managed device operates an Agent. The agent translates the status or configuration of the device into a format understood by the SNMP protocol.
There are 7 different types of SNMP packets.
GetRequest: is initiated by the manager to retrieve information from the managed device.
SetRequest: is initiated by the manager to set information on the managed device.
GetNextRequest: Discovers available variables and their values on a managed device
GetBulkRequest: introduced in SNMPv2c, is multiple GetNextRequests send by the manager.
Response: The response returned by the client for requests sent by the manager.
Trap: An aysnchronous notification from the managed device to the manager. This is the only type of SNMP packet which is not actively requested from the manager.
InformRequest: Introduced in SNMPv2c, and is considered manager to manager communication.