3M 965DPS instruction manual Adsl Alarms

DSLAM modem manufacturer information is displayed if available, but this feature is not supported by all service types or manufacturers. The 965DSP displays ‘unknown’ in this field if the DSLAM manufacturer information is unavailable.

FEC, CRC, and HEC counts in each direction are also displayed. FEC is the number of Forward Error Correction events in each direction. These are automatically corrected errors, and as such they do not require re-transmission of data. CRC is the number of Cyclic Redundancy Check errors detected in each direction. These numeric checks indicate that the ADSL data frame had one or more uncorrected errors, so the data must be re-transmitted reducing throughput. HEC is the number of Asynchronous Transfer Mode (ATM) cell Header Error Correction events detected in each direction. ADSL normally carries data in ATM format to remain synchronous with data on the network. For the modem in the 965DSP, dummy 53-byte ATM data cells are inserted to maintain proper timing with the DSLAM. The cell header field integrity is checked separately since it directs the data cell to its destination, and errors in the header can cause the loss of an entire data cell.

Press the Alarms key to display more ADSL modem connection information or the Status key to return to the previous screen.

ADSL Alarms

This screen displays any detected ADSL link alarm conditions. If a link alarm occurs at any time during the connection, the link alarm history is set to ‘Yes’ and remains in that state for the duration of the connection.

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