Specifications

Management Guide CLI
TigerAccess™ EE
SMC7824M/VSW 89
with or less than the noise strength, stable communication cannot be done. Therefore,
SNT must not be minus or “0”. And, if there is this situation, you have to increase signal
strength or decrease noise strength.
Transmit rate of VDSL line depends of SNR. But, environment of line cannot be always
same. So you need to configure transmit rate of VDSL line can be decided according to
changing line environment. If noise is suddenly increased, SNR is decreased and com-
munication becomes unstable.
Therefore you should configure transmit rate for decreased SNR when noise is suddenly
increased. Then there will not be problem with communication although noise is suddenly
increased.
Fig. 5.3 Deciding Transmit Rate according to SNR Margin
When you configure estimate SNR, the difference between estimate SNR and current
SNR is call「SNR Margin」. The switch applies the SNR margin to transmit rate In other
word, if you configure SNR margin as “6”, the difference that subtracts 6 from current
SNR will be applied to transmit rate as the above picture
In you think there will be big change of noise, configure big SNR margin. However, if you
configure too big SNR margin, transmit rate will be slow down, whereas communication is
stable.
To configure SNR margin, use the following command.
Command Mode Description
lre PORTS snr-target-margin <0-
31> [up | down]
Configures SNR margin of Downstream or Upstream.
0-31: SNR margin value (default:6 dB)
lre PORTS snr-min-margin <0-
31> [up | down]
Bridge
Configures minimum SNR margin
0-31: minimum SNR margin value (default: 5 dB)