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Prestige 2602HWNLI-D7A Support Notes
All contents copyright (c) 2007 ZyXEL Communications Corporation.
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Network Management Using SNMP
1. SNMP Overview
The
Simple Network Management Protocol
(SNMP) is an applications-layer protocol used to exchange the
management information between network devices (e.g., routers). By using SNMP, network administrators can
more easily manage network performance, find and solve network problems. The SNMP is a member of the
TCP/IP protocol suite, it uses the UDP to exchange messages between a management Client and an Agent,
residing in a network node.
There are two versions of SNMP: Version 1 and Version 2. ZyXEL supports SNMPv1. Most of the changes
introduced in Version 2 increase SNMP's security capabilities. SNMP encompasses three main areas:
1. A small set of management operations.
2. Definitions of management variables.
3. Data representation.
The operations allowed are: Get, GetNext, Set, and Trap. These functions operates on variables that exist in
network nodes. Examples of variables include statistic counters, node port status, and so on. All of the SNMP
management functions are carried out through these simple operations. No action operations are available, but
these can be simulated by the setting of flag variables. For example, to reset a node, a counter variable named
'time to reset' could be set to a value, causing the node to reset after the time had elapsed.
SNMP variables are defined using the OSI Abstract Syntax Notation One (ASN.1). ASN.1 specifies how a
variable is encoded in a transmitted data frame; it is very powerful because the encoded data is self-defining.
For example, the encoding of a text string includes an indication that the data unit is a string, along with its
length and value. ASN.1 is a flexible way of defining protocols, especially for network management protocols
where nodes may support different sets of manageable variables.
The net of variables that each node supports is called the
Management Information Base
(MIB). The MIB is
made up of several parts, including the Standard MIB, specified as part of SNMP, and Enterprise Specific MIB,
which are defined by different manufacturer for hardware specific management.