Qtech QSW-2900-24T-AC [35/209] Snmp mechanism

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information, find and diagnose network problems, plan for network growth, and generate reports on network

nodes.

· SNMP shields the physical differences between various devices and thus realizes automatic management of

products from different manufacturers. Offering only the basic set of functions, SNMP makes the

management tasks independent of both the physical features of the managed devices and the underlying

networking technology. Thus, SNMP achieves effective management of devices from different manufactures,

especially so in small, fast and low cost network environments.

2.6 SNMP Mechanism

An SNMP enabled network is comprised of network management station (NMS) and Agent.

· NMS is a station that runs the SNMP client software. It offers a user friendly human computer interface,

making it easier for network administrators to perform most network management tasks. Currently, the most

commonly used NMSs include Quidview, Sun NetManager, and IBM NetView.

· Agent is a program on the device. It receives and handles requests sent from the NMS. Only under certain

circumstances, such as interface state change, will the Agent inform the NMS.

· NMS manages an SNMP enabled network, whereas Agent is the managed network device. They exchange

management information through the SNMP protocol.

SNMP provides the following four basic operations:

· Get operation: NMS gets the value of a certain variable of Agent through this operation.

· Set operation: NMS can reconfigure certain values in the Agent MIB (Management Information Base) to

make the Agent perform certain tasks by means of this operation.

· Trap operation: Agent sends Trap information to the NMS through this operation.

· Inform operation: NMS sends Trap information to other NMSs through this operation.

2.7 SNMP Protocol Version

Currently, SNMP agents support SNMPv3 and are compatible with SNMPv1 and SNMPv2c.

SNMPv1 and SNMPv2c authenticate by means of community name, which defines the relationship between

an SNMP NMS and an SNMP Agent. SNMP packets with community names that did not pass the authentication on

the device will simply be discarded. A community name performs a similar role as a key word and can be used to

regulate access from NMS to Agent.

SNMPv3 offers an authentication that is implemented with a User-Based Security Model (USM for short),

which could be authentication with privacy, authentication without privacy, or no authentication no privacy. USM

regulates the access from NMS to Agent in a more efficient way.

2.8 MIB Overview

Management Information Base (MIB) is a collection of all the objects managed by NMS. It defines the set of

characteristics associated with the managed objects, such as the object identifier (OID), access right and data type of

the objects.

MIB stores data using a tree structure. The node of the tree is the managed object and can be uniquely

identified by a path starting from the root node. As illustrated in the following figure, the managed object B can be

uniquely identified by a string of numbers {1.2.1.1}. This string of numbers is the OID of the managed object B.