ZyXEL Communications P-873HNU-51B, User Manual

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Chapter 25 xDSL Statistics
P-873HNU(P)-51B User’s Guide
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The following table describes the labels in this screen.
Table 97
Status > xDSL Statistics
LABEL DESCRIPTION
Refresh Interval Select the time interval for refreshing statistics.
Line Select which DSL line’s statistics you want to display.
xDSL Training
Status This displays the current state of setting up the DSL connection.
Mode This displays the ITU standard used for this connection.
Traffic Type This displays the type of traffic the DSL port is sending and receiving. Inactive
displays if the DSL port is not currently sending or receiving traffic.
Link Uptime This displays how long the port has been running (or connected) since the last
time it was started.
xDSL Port Details
Upstream These are the statistics for the traffic direction going out from the port to the
service provider.
Downstream These are the statistics for the traffic direction coming into the port from the
service provider.
Line Rate These are the data transfer rates at which the port is sending and receiving data.
Actual Net Data
Rate These are the rates at which the port is sending and receiving the payload data
without transport layer protocol headers and traffic.
Trellis Coding This displays whether or not the port is using Trellis coding for traffic it is sending
and receiving. Trellis coding helps to reduce the noise in ADSL transmissions.
Trellis may reduce throughput but it makes the connection more stable.
SNR Margin This is the upstream and downstream Signal-to-Noise Ratio margin (in dB). A
DMT sub-carrier’s SNR is the ratio between the received signal power and the
received noise power. The signal-to-noise ratio margin is the maximum that the
received noise power could increase with the system still being able to meet its
transmission targets.
Actual Delay This is the upstream and downstream interleave delay. It is the wait (in
milliseconds) that determines the size of a single block of data to be interleaved
(assembled) and then transmitted. Interleave delay is used when transmission
error correction (Reed- Solomon) is necessary due to a less than ideal telephone
line. The bigger the delay, the bigger the data block size, allowing better error
correction to be performed.
Transmit Power This is the upstream and downstream far end actual aggregate transmit power (in
dBm).
Upstream is how much power the port is using to transmit to the service provider.
Downstream is how much port the service provider is using to transmit to the
port.
Receive Power Upstream is how much power the service provider is receiving from the port.
Downstream is how much power the port is receiving from the service provider.
Actual INP Sudden spikes in the line’s level of external noise (impulse noise) can cause errors
and result in lost packets. This could especially impact the quality of multimedia
traffic such as voice or video. Impulse noise protection (INP) provides a buffer to
allow for correction of errors caused by error correction to deal with this. The
number of DMT (Discrete Multi-Tone) symbols shows the level of impulse noise
protection for the upstream and downstream traffic. A higher symbol value
provides higher error correction capability, but it causes overhead and higher
delay which may increase error rates in received multimedia data.
Total Attenuation This is the upstream and downstream line attenuation, measured in decibels (dB).
This attenuation is the difference between the power transmitted at the near-end
and the power received at the far-end. Attenuation is affected by the channel
characteristics (wire gauge, quality, condition and length of the physical line).