Chapter 34 Access Control

Figure 114 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 device (the IES-612- 51A). An agent translates the local management information from the managed device 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 device. Examples of variables include such as number of packets received, node port status etc. 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 74 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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IES-612-51A User’s Guide