ZyXEL ES-2024 Series User Manual download pdf (Page 198)

Chapter 27 Access Control

ES-2024 Series User’s Guide

198

27.3 About SNMP

Simple Network Management Protocol (SNMP) is an application layer protocol used to

manage and monitor TCP/IP-based devices. SNMP is used to exchange management

information between the network management system (NMS) and a network element (NE). A

manager station can manage and monitor the Switch through the network via SNMP version

one (SNMPv1), SNMP version 2c or SNMP version 3. The next figure illustrates an SNMP

management operation. SNMP is only available if TCP/IP is configured.

Figure 113 SNMP Management Model

An SNMP managed network consists of two main components: agents and a manager.

An agent is a management software module that resides in a managed Switch (the Switch). An

agent translates the local management information from the managed Switch into a form

compatible with SNMP. The manager is the console through which network administrators

perform network management functions. It executes applications that control and monitor

managed devices.

The managed devices contain object variables/managed objects that define each piece of

information to be collected about a Switch. Examples of variables include number of packets

received, node port status and so on. A Management Information Base (MIB) is a collection of

managed objects. SNMP allows a manager and agents to communicate for the purpose of

accessing these objects.

SNMP itself is a simple request/response protocol based on the manager/agent model. The

manager issues a request and the agent returns responses using the following protocol

operations:

Table 75 SNMP Commands

COMMAND DESCRIPTION

Get Allows the manager to retrieve an object variable from the agent.

GetNext Allows the manager to retrieve the next object variable from a table or list within an

agent. In SNMPv1, when a manager wants to retrieve all elements of a table from an

agent, it initiates a Get operation, followed by a series of GetNext operations.

Set Allows the manager to set values for object variables within an agent.

Trap Used by the agent to inform the manager of some events.

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ZyXEL ES-2024 Series User Manual Page 198