Chapter 27 Access Control
27.3 About SNMP
Simple Network Management Protocol (SNMP) is an application layer protocol used to manage and monitor
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. |
|
|
198 |
| |
| ||
|
|
|