ZyXEL Communications VES1724-56 User Manual page 110

Chapter 9 VDSL Setup
Table 35 VDSL Rate Adaptive Setup (continued)
LABEL
Rate Adaptive
DynamicDepth
Up-Shift SNR Margin Enter the number of decibels (dB) for the line's up-shift SNR margin threshold. When
Up-Shift Time
Down-Shift SNR
Margin
Down-Shift Time
Modify
SOS Time
SOS CRC
SOS nTones
SOS Max
SOS Multi-Step
Tones
ROC enable
ROC SNR Margin
ROC min INP
110
DESCRIPTION
Select the rate adaptive modes for downstream and upstream transmissions.
Select Manual to fix the transmit rate as the minimum net data rate and disable
transmission rate adjustment. If the attainable speeds cannot match configured speeds,
then the VDSL link may go down or link communications may be sporadic due to line
errors and consequent retransmissions.
Select AdaptInit to keep the transmit rate negotiated between CO and CPE devices. It
ranges from the configured minimum to the maximum net data rate based on the initial
line condition.
Select Dynamic to dynamically change the transmission rate negotiated between the
Switch and CPE devices during initialization as well as during SHOWTIME status.
Select SOS to use the emergency rate adjustment system for immediate rate
adjustment to reduce crosstalk noise.
Select Enable to allow the Switch to dynamically change interleaving depth for
downstream or upstream traffic. In addition, this enables the Switch to change the
lower and upper boundaries of the net data rate and improve the ability of SRA
(Seamless Rate Adaptation). Alternatively, select Diable to have the Switch use a fixed
interleaving depth.
the line's signal-to-noise margin goes above this number, the Switch attempts to use a
higher transmission rate.
Enter the number of seconds the Switch has to wait before using a higher transmission
rate when the line's SNR margin is over the up-shift SNR margin threshold.
Enter the number of decibels (dB) for the line's down-shift SNR margin threshold. When
the line's signal-to-noise margin goes below this number, the Switch attempts to use a
lower transmission rate.
Enter the number of seconds the Switch waits before using a lower transmission rate
when the line's SNR margin is less the down-shift SNR margin threshold.
Click this to save the settings to the Switch and return to the previous screen.
Specify the time interval (from 64 to 16320) at which the Switch initiates an SOS
request.
Specify the maximum number of CRC errors which are allowed during the specified SOS
time interval before the Switch initiates an SOS request.
Specify the maximum percentage (from 0 to 100) of persistently degraded tones in the
MEDLEY set which are allowed during the specified SOS time interval before the Switch
initiates an SOS request.
Specify the maximum number (from 0 to 15) of successful SOS processes which are
allowed within 120 seconds before the Switch goes to the L3 link state. An SOS process
is considered successful when the Switch receives a synchronous signal (SyncFlag).
Select to adjust bits for all tones in an SOS request.
A ROC (robust overhead channel) is a latency path that carries only overhead data.
Select Enable to use a ROC to transmit SOS information to ensure that the message
can be received correctly. Otherwise, select Disable.
Specify the (Signal to Noise Ratio) margin allowed for a robust overhead channel. When
the actual SNR margin is going to reach this specified value, a robust overhead channel
is negotiated for reliable transmission.
Specify the level of impulse noise (burst) protection for a robust overhead channel.
Select a number between 0 and 16.
VES1724-56 User's Guide