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DSL-G624T Wireless A DSL Router User’s Guide
ATM Traffic Shaping
The ATM settings in the WAN configuration menus for the different connection types can be used to adjust QoS
parameters for ADSL clients. This may not be available to all ADSL accounts. Ask your ISP if ATM
ATM Settings for WAN connection (PPPoE/PPPoA menu)
Additional ATM settings for PPPoE or PPPoA connections:
ATM QoS Parameters Description
Service Category
The ATM settings allow the user to adjust ATM Quality of Service (QoS) or
traffic parameters to suit specific traffic requirements. For applications or
circumstances where packet loss or packet delay are a concern, ATM QoS
can be adjusted to minimize problems. For most accounts, it will not be
necessary to change these settings. Altering QoS settings can adversely
affect performance of some commonly used Internet applications.
If you plan to change QoS or traffic parameters, contact your ISP or network
services provider for information on what types of adjustment are available
or possible for your account. Your ISP may not support the class of service
you want to use.
To adjust ATM QoS parameters, select one of the Service Categories listed
here and type in the PCR value in the entry field below. For the VBR service
category, an additional parameter (SCR) must also be defined.
UBR – Unspecified Bit Rate, this is the default category used for
general-purpose Internet traffic where normal levels of packet loss and
delay are acceptable. For some applications or for multiple connection
accounts, it may be desirable to specify the PCR.
CBR – Constant Bit Rate, usually used in circumstances where very
low packet loss and very low Cell Delay Variable (CDV) are desirable.
VBR – Variable Bit Rate, usually used when network traffic is
characterized by bursts of packets at variable intervals, and some
moderate packet loss and delay is acceptable. This category is
typically used for audio and video applications such as
teleconferencing. The network must support QoS Class 2 to use VBR.
PCR
Peak Cell Rate – The PCR is inversely related to the time interval between
ATM cells. It is specified for all three service categories (UBR, CBR and
VBR) in Kbps.
SCR
Sustainable Cell Rate – The SCR is defined for the VBR service category.
This is the rate that can be sustained for “bursty”, on-off traffic sources. It is
a function of Maximum Burst Size (MBS) and the time interval (between
cells).
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