Introduction to SNMP

SNMP – Simple Network Management Protocol
When using SNMP, typically one or more managers to monitor a group of manged devices.

SNMP network consists of 3 components:

  • Managed Device
  • Agent – software that runs on the managed devices, contains information of the managed device and translates it to and from SNMP forms
  • Network Management System (NMS) – software running on the managers that monitors and control managed devices on the network.

There are 3 Versions – SNMPv1, SNMPv2, SNMPv3


  • Initial implementation
  • Contains 5 core PDUs( protocol data units)
    • GetRequest – Sent from manager to agent to retrieve the value of a variable or set of variables
    • SetRequest – Sent from manager to agent to request to change the value of a variable or set of variables
    • GetNextRequest – Sent from manager to agent to discover any available variables and their values.
    • Response – Sent from agent to manager to return variable bindings and acknowledge GetRequest, SetRequest and GetNextRequest messages
    • Trap – Sent from agent to manager to notify the manager about something.


  • Revises v1 and improves performance, security, confidentiality and manager-to-manager communication.
  • Adds to more PDUs
    • GetBulkRequest – Sent from manager to agent to request multiple iterations of the GetNextRequest.
    • InformRequest – Sent from manager to manager, or from agent to manager. Receiver responds with an acknowledge.

SNMPv2 is incompatible with SNMPv1 with regards to message formats and protocol operations.


  • Adds security and remote configuration enhancements.
  • Provides security through confidentiality, integrity, and authentication.

SNMP implementations often support multiple versions: typically SNMPv1, SNMPv2c*, and SNMPv3

* SNMPv2c – Community-Based Simple Network Management Protocol version, uses same security model as SNMPv1.

For more information about SNMP please to some of the following links:

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Posted in SNMP