ZyXEL Communications Prestige 861H-G1, User Manual

Page: 252 / 275

Prestige 861H User’s Guide
34-2 VDSL Commands
Table 34-1 VDSL Command Summary
MODULE COMMAND SUB-COMMAND ARGUMENTS DESCRIPTION
show Display all detailed attributes of the
current or default profile.
pvc list Display all detailed attributes of the
current or default profile.
version This command displays the driver
session.
34.3 VDSL Default Values
The default values for the following VDSL parameters are shown in the next table.
Table 34-2 VDSL Default Values
VDSL PARAMETER DEFAULT VALUE
VDSL Active on
VDSL Upstream Power Backoff(UPBO) Option disable
VDSL Channel Type (Latency Mode) interleave
Upstream Max interleave delay 10ms
Downstream Max interleave delay 10ms
VDSL Band Modifier 0x11 (The lowest DS frequency starts from 138KHz.)
34.3.1 Service Categories
Service categories ensure that high priority transmissions get the bandwidth they need.
CBR (Constant Bit Rate) provides a fixed amount of bandwidth that is always available even if
no data is being sent. A PCR is specified and if traffic exceeds this rate, cells may be dropped. An
example application is a T1 circuit.
rt-VBR (real-time Variable Bit Rate) also provides a fixed amount of bandwidth (a PCR is
specified) but is only available when data is being sent. An example application is real-time
videoconferencing.
nrt-VBR (non-real-time Variable Bit Rate) is commonly used for “bursty” traffic typical on
LANs. PCR and MBS define the burst levels, SCR defines the minimum level. An example
application is multimedia e-mail.
Unspecified Bit Rate (UBR) does not guarantee bandwidth or throughput. Cells are dropped if
there is not enough bandwidth. Only the PCR is set. An example application is background file
transfer.
Table 34-3 Service Characteristic
CHARACTERISTIC CBR RT-VBR NRT-VBR UBR
Guaranteed Bandwidth 3 3 3 2
Good for Real-Time Traffic 3 3 2 2
Suitable for Bursty Traffic 2 2 3 3