80
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.