P-660 series Support Notes
ost 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.
3. Data representation.
The operations allowed are: Get, GetNext, Set, and Trap. These functions operates
on vari e statistic
counters, node port status, and so on. All of the SNMP management functions are
carr
these ca e, a
counter set
after th
SNMP variables are defined using the OSI Abstract Syntax Notation One (ASN.1).
ASN.1
powerf
text str its length and
valu ecially for network
manage anageable
variab
The net of variab Management Information
Bas , including the Standard MIB,
specified as part of SNMP, and Enterprise Specific MIB, which are defined by
The current Internet-standard MIB, MIB-II, is defined in RFC 1213 and contains 171
ouped by protocol (including TCP, IP, UDP, SNMP, and
other categories, including 'system' and 'interface.'
NMS and managed devices can be any of four different types of commands:
Reads
d to monitor the managed devices, NMSs read variables that are
maintained by the devices.
Writes
Write is used to control the managed devices, NMSs write variables that are
stored in the managed devices.
There are two versions of SNMP: Version 1 and Version 2. ZyXEL supports
SNMPv1. M
Definitions of management variables.
ables that exist in network nodes. Examples of variables includ
ied out through these simple operations. No action operations are available, but
n be simulated by the setting of flag variables. For example, to reset a nod
variable named 'time to reset' could be set to a value, causing the node to re
e time had elapsed.
specifies how a variable is encoded in a transmitted data frame; it is very
ul because the encoded data is self-defining. For example, the encoding of a
ing includes an indication that the data unit is a string, along with
e. ASN.1 is a flexible way of defining protocols, esp
ment protocols where nodes may support different sets of m
les.
les that each node supports is called the
e (MIB). The MIB is made up of several parts
different manufacturer for hardware specific management.
objects. These objects are gr
The Internet Management Model is as shown in figure 1. Interactions between the
Read is use
83
All contents copyright © 2005 ZyXEL Communications Corporation.
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