D-Link DSL-2540T User Manual page 33

WAN Setting
Connection Type
Service Category
PCR
SCR
CDVT
MBS
DSL-2540T ADSL Router User Guide
enable or disable the PVC you are currently configuring. By default, the
Enabled
Pvc0 is and the remaining PVCs are disabled.
Use the drop-down menu to select
Dynamic IP Address
are
This specifies the protocol (Bridge Mode) and the encapsulation method
(LLC or VC-Mux) used for your connection. The options available are
1483 Bridged IP LLC
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 is 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.
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.
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).
Cell Delay Variation Tolerance – CDVT is a measure of the cell clumping
phenomenon by which cells are delayed in the network and are
clumped together and arrive at a system at a faster rate than
negotiated.
Increasing the CDVT creates greater bucket depth.
Maximum Burst Size – The MBS is the maximum number of bytes that
can be sent continuously from the source to the destination dropping
any packets. Some ATM providers set the MBS and CDVT very low and
adjust up if problems occur.
26
Bridge Mode
Static IP Address
, , and
1483 Bridged IP VC-Mux
and
. The remaining options
PPPoE/PPPoA
.
.