ZyXEL VMG4380 User Guide - Page 252
Table 100, Label, Description
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Chapter 25 xDSL Statistics The following table describes the labels in this screen. Table 100 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 These are the rates at which the port is sending and receiving the payload data without Rate 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 subcarrier'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 MultiTone) 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). Attainable Net Data Rate These are the highest theoretically possible transfer rates at which the port could send and receive payload data without transport layer protocol headers and traffic. xDSL Counters 252 VMG4380-B10A / VMG4325-B10A User's Guide