Configuring the T1 Physical Link
•Clock Source
•Facility Data Link
•Framing
•Inband Loopback Detection
•Linecoding
•Yellow Alarms
Alarms
The T1 standard, ANSI T1.403, Bellcore
A red alarm occurs when the T1 signal is lost or an out of frame error occurs. An out of frame error can be caused when the framing type configured for the local interface does not match the framing type of the incoming T1 signal or when the incoming signal does not contain a T1 framing pattern.
A yellow alarm is also called a Remote Alarm Indication (RAI). When the remote end of a link does not receive a signal, it will transmit a yellow alarm signal back to the local end.
A blue alarm is also called an Alarm Indication Signal (AIS). A blue alarm indicates that a device somewhere upstream has experienced a loss of signal.
The default value is on. To configure whether alarms are generated and detected, use the following command:
config ports <portlist> t1 alarms [on off]
Yellow alarms can be configured when T1 alarms are enabled. See “Yellow Alarms” on page
config ports <portlist> t1 yellow [detection generation both off]
Cable length
Longer cable lengths cause greater loss for the T1 signal, so the transmitter hardware must transmit at a higher level to transmit data successfully. However, too high a signal level can cause crosstalk from one cable to another. The config ports t1
