ZyXEL Communications MES3500 Series, User Manual

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Chapter 40 Access Control
MES3500 Series User’s Guide
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SNMP version 3. The next figure illustrates an SNMP management operation. SNMP is only available
if TCP/IP is configured.
Figure 195
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:
40.3.1 SNMP v3 and Security
SNMP v3 enhances security for SNMP management. SNMP managers can be required to
authenticate with agents before conducting SNMP management sessions.
Security can be further enhanced by encrypting the SNMP messages sent from the managers.
Encryption protects the contents of the SNMP messages. When the contents of the SNMP messages
are encrypted, only the intended recipients can read them.
Table 142
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.