ZyXEL VMG4927-B50A User Guide - Page 251

Chapter 27 xDSL Statistics Table 117 Status > xDSL Statistics (continued) LABEL DESCRIPTION xDSL Training Status Mode Traffic Type Link Uptime xDSL Port Details Upstream Downstream Line Rate Actual Net Data Rate Trellis Coding SNR Margin Actual Delay Transmit Power This displays the current state of setting up the DSL connection. This displays the ITU standard used for this connection. 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. This displays how long the port has been running (or connected) since the last time it was started. These are the statistics for the traffic direction going out from the port to the service provider. These are the statistics for the traffic direction coming into the port from the service provider. These are the data transfer rates at which the port is sending and receiving data. These are the rates at which the port is sending and receiving the payload data without transport layer protocol headers and traffic. 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. 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 signalto-noise ratio margin is the maximum that the received noise power could increase with the system still being able to meet its transmission targets. 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. This is the upstream and downstream far end actual aggregate transmit power (in dBm). Receive Power Actual INP Attainable Net Data Rate xDSL Counters Downstream Upstream FEC CRC ES SES UAS 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. 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. 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. 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. These are the statistics for the traffic direction coming into the port from the service provider. These are the statistics for the traffic direction going out from the port to the service provider. This is the number of Far End Corrected blocks. This is the number of Cyclic Redundancy Checks. This is the number of Errored Seconds meaning the number of seconds containing at least one errored block or at least one defect. This is the number of Severely Errored Seconds meaning the number of seconds containing 30% or more errored blocks or at least one defect. This is a subset of ES. This is the number of UnAvailable Seconds. VMG4927-B50A / VMG9827-B50A User's Guide 251