ZyXEL Communications U-336R/RE User Manual page 137

T401 Timeouts and T402 Timeouts
These are for the manufacturer checking link layer operation. T401
and T402 are timers used in MNP4 or V.42. T402 will count when
the modem is connected in the idle state with no data to transmit or
receive.
FCS Errors
Frame CheckSum Errors/number of block errors. A lot of FCS
errors indicate a bad line.
Round Trip Delay
Round trip delay between modems in T (1/2400 sec) units.
Normally should be in the range of 0-100. A satellite link will
introduce a delay of about 1300 T.
Xmitter Underrun
Number of times the modem fails to provide data octet in time for
transmission.
Receiver Overrun
Number of times the modem fails to take data octet in time from
receiver.
Last speed/protocol
The speed and protocol of the link before hang-up. It may be
different from the initial speed because of retrain and speed fall-
back or fall-forward. Speed change is a clue to changing line
conditions.
Disconnect Reason
Local Hang-up
Remote Hang-up
Carrier Lost
On Line
Diagnostics & Troubleshooting 125