What is SNMP?

SNMP stands for Simple Network Management Protocol.

It is a standard protocol used to monitor and manage devices on a network — such as routers, switches, servers, printers, and more. SNMP allows administrators to collect information, modify settings, and detect problems across a network.

How SNMP works:

• Key components:
  
1. Managed Devices: Devices like routers, switches, or servers that support SNMP and have data to share.
2. Agents: Software running on managed devices that collects and stores management information (like CPU usage, network traffic) and communicates with the SNMP manager.
3. Network Management System (NMS): A centralized software that queries agents and displays the collected information for monitoring and management.
• Data format:
  
1. Each piece of information is stored in a structure called a Management Information Base (MIB) — basically a database of all the readable parameters on the device (like device name, uptime, traffic rates).
• Communication:
  
1. The NMS sends SNMP requests (like GET, SET, GETNEXT) to agents.
2. Agents respond with the requested information or acknowledge changes.
3. Devices can also send traps (unsolicited alerts) to the NMS when something important happens, like a link going down.
• Versions:
  There are different versions of SNMP:
  
1. SNMPv1: Original, very basic, little security.
2. SNMPv2c: Improved performance, but still uses “community strings” (simple passwords).
3. SNMPv3: Adds strong security features like authentication and encryption.

Example:

Imagine you are managing a big office network:

• You can use an SNMP-based monitoring tool to automatically check every device’s CPU load, network usage, temperature, and status without logging into each device manually.
• If a router crashes or a link fails, the agent immediately sends a trap to alert you.