Overview of SNMP

Definition

SNMP is a standard network management protocol that is widely used on TCP/IP networks. The SNMP framework manages network elements using a central computer, known as a network management station (NMS), on which network management software is installed. SNMP offers simplicity and power.

Simplicity: SNMP uses a polling mechanism and provides basic network management functions, making it applicable to small-scale networks that are sensitive to speed and cost. Moreover, SNMP messages are carried in UDP packets, which are supported by most network devices.
Power: SNMP allows management information exchange between any two devices on a network, allowing network administrators to query information and locate faults anywhere on the network.

Purpose

As networks rapidly grow in scale and applications become more diversified, network administrators face the following problems:

The rapid growth in the number of network devices increases the workload for network administrators. In addition, networks' coverage areas are constantly being expanded, making real-time monitoring and fault location of network devices difficult.
Networks have many types of devices, and the management interfaces on devices of different vendors conform to different standards. This makes network management complex.

SNMP was developed to address these problems. SNMP supports batch management of network devices and implements unified management of devices of different types and vendors.

Version Evolution

SNMPv1 is the initial version of the SNMP protocol. It is defined in RFC 1157 drafted in May 1990. RFC 1157 provides a systematic method for monitoring and managing networks. However, SNMPv1 cannot ensure the security of networks because it is implemented based on community names and provides only a few error codes.

In 1996, the Internet Engineering Task Force (IETF) defined SNMPv2c in RFC 1901. SNMPv2c uses GetBulk and Inform operations and provides more error codes and data types (including Counter64 and Counter32) than SNMPv1.

To provide improved security protection measures, IETF released SNMPv3. SNMPv3 provides encryption and authentication based on the user-based security model (USM) and access control based on the view-based access control model (VACM).

Benefits

Improved work efficiency: A network administrator can use SNMP to query information, modify information, and locate faults on any device.
Reduced management costs: SNMP provides a basic function set to manage devices that have different management tasks, physical attributes, and network types.
Reduced impact of feature configuration operations on devices: SNMP is simple in terms of hardware/software installation, packet type, and packet format.