About Snmp - ZyXEL Communications XMG1915 Series User Manual

26.6.1 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 through SNMP version 1 (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 116 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 or 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 or response protocol based on the manager or agent model. The
manager issues a request and the agent returns responses using the following protocol operations:
Table 75 SNMP Commands
LABEL
Get
GetNext
Set
Trap
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.
Chapter 26 SNMP
DESCRIPTION
Allows the manager to retrieve an object variable from the agent.
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.
Allows the manager to set values for object variables within an agent.
Used by the agent to inform the manager of some events.
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