AAM1212 User’s Guide
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Chapter 8 ADSL Port Setup
8.11 ATM QoS
ATM Quality of Service (QoS) mechanisms provide the best service on a per-flow guarantee.
ATM network infrastructure was designed to provide QoS. It uses fixed cell sizes and built-in
traffic management (see the following section on traffic shaping). This allows you to fine-tune
the levels of services on the priority of the traffic flow.
8.12 Traffic Shaping
Traffic shaping is an agreement between the carrier and the subscriber to regulate the average
rate and fluctuations of data transmission over an ATM network. This agreement helps
eliminate congestion, which is important for transmission of real time data such as audio and
video connections.
8.12.1 ATM Traffic Classes
These are the basic ATM traffic classes defined by the ATM Forum Traffic Management 4.0
Specification.
8.12.1.1 Constant Bit Rate (CBR)
Constant Bit Rate (CBR) is an ATM traffic class that provides fixed bandwidth. CBR traffic is
generally time-sensitive (doesn't tolerate delay). CBR is used for connections that
continuously require a specific amount of bandwidth. Examples of connections that need CBR
would be high-resolution video and voice.
8.12.1.2 Variable Bit Rate (VBR)
The Variable Bit Rate (VBR) ATM traffic class is used with bursty connections. Connections
that use the Variable Bit Rate (VBR) traffic class can be grouped into real time (rt-VBR) or
non-real time (nrt-VBR) connections.
The rt-VBR (real-time Variable Bit Rate) type is used with bursty connections that require
closely controlled delay and delay variation. An example of an rt-VBR connection would be
video conferencing. Video conferencing requires real-time data transfers and the bandwidth
requirement varies in proportion to the video image's changing dynamics.
The nrt-VBR (non real-time Variable Bit Rate) type is used with bursty connections that do
not require closely controlled delay and delay variation. An example of an nrt-VBR
connection would be non-time sensitive data file transfers.
Summary of Contents for AAM1212
Page 1: ...AAM1212 ADSL2 Module over POTS in the IP DSLAM User s Guide Version 3 50 9 2005 ...
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Page 35: ...AAM1212 User s Guide 34 Chapter 1 Getting to Know Your AAM1212 ...
Page 49: ...AAM1212 User s Guide 48 Chapter 3 Hardware Connections ...
Page 55: ...AAM1212 User s Guide 54 Chapter 4 Web Configurator Introduction ...
Page 63: ...AAM1212 User s Guide 62 Chapter 5 Initial Configuration ...
Page 71: ...AAM1212 User s Guide 70 Chapter 6 Home and Port Statistics Screens ...
Page 83: ...AAM1212 User s Guide 82 Chapter 7 Basic Setting Screens ...
Page 111: ...AAM1212 User s Guide 110 Chapter 8 ADSL Port Setup ...
Page 143: ...AAM1212 User s Guide 142 Chapter 18 Syslog ...
Page 151: ...AAM1212 User s Guide 150 Chapter 19 Access Control ...
Page 163: ...AAM1212 User s Guide 162 Chapter 22 Diagnostic ...
Page 181: ...AAM1212 User s Guide 180 Chapter 25 Commands Overview ...
Page 249: ...AAM1212 User s Guide 248 Chapter 29 IP Commands ...
Page 261: ...AAM1212 User s Guide 260 Chapter 30 Statistics Commands ...
Page 277: ...AAM1212 User s Guide 276 Chapter 33 Troubleshooting ...
Page 283: ...AAM1212 User s Guide 282 Virtual Circuit Topology ...