4-1-7 SNMP (Simple Network Management Protocol) Explained

Key Concepts

• SNMP Overview
• SNMP Components
• SNMP Operations
• SNMP Security

SNMP Overview

SNMP (Simple Network Management Protocol) is an Internet Standard protocol used for collecting and organizing information about managed devices on IP networks and for modifying that information to change device behavior. It is widely used for network management systems to monitor network-attached devices for conditions that warrant administrative attention.

SNMP Components

SNMP consists of several key components:

• Managed Devices: Network devices that contain an SNMP agent and are monitored and controlled by an NMS (Network Management System).
• SNMP Agent: A software module that resides on a managed device and provides access to local management information.
• NMS (Network Management System): A system that executes network management applications, which provide the network administrator with the ability to monitor and control network operations.
• MIB (Management Information Base): A virtual database used to manage the entities in a communications network.

SNMP Operations

SNMP defines several operations for communication between the NMS and managed devices:

• Get: Used by the NMS to retrieve the value of an object from the agent.
• Set: Used by the NMS to change the value of an object in the agent.
• Trap: Used by the agent to send unsolicited notifications to the NMS.
• GetBulk: Used to retrieve large blocks of data, such as multiple rows of a table, efficiently.
• Inform: Similar to a trap, but requires an acknowledgment from the NMS.

SNMP Security

SNMP security is crucial to protect the integrity and confidentiality of network management data. Key security measures include:

• Community Strings: Simple passwords used to authenticate SNMP messages in SNMPv1 and SNMPv2c.
• SNMPv3: Introduces security features such as authentication, privacy (encryption), and access control.
• Access Control: Defines which users or systems have permission to perform specific SNMP operations.

Examples and Analogies

Think of SNMP as a remote control system for a network. The NMS is like a central control room where an operator monitors and controls various devices (managed devices). The SNMP agent on each device is like a sensor that sends data back to the control room and responds to commands. The MIB is like a database that stores all the information about the devices.

Another analogy is a security system in a building. The NMS is like the security control center, the managed devices are like security cameras and sensors, the SNMP agent is like the communication module in each device, and the MIB is like the logbook that records all the events.