User`s manual

P-660 Series Support Notes

Password

Enter the password that the DDNS server gives to you.

Enable Wildcard

Enter the hostname for the wildcard function that the

WWW.DYNDNS.ORG supports. Note that Wildcard option is available

only when the provider is http://www.dyndns.org/

8. Network Management Using SNMP

• 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.