One tricolor per port:
OffNot enabled
GreenOnline with no alarms or failures
AmberOnline with alarms for remote failures
RedActive with a local alarm; router has detected a failure
LEDs
Alarm indication signal (AIS)
Frame error
Line code violation
Local and remote loopback
Loss of signal (LOS)
Out of frame (OOF)
Yellow alarm
Alarms, errors, and
events
16 ATM2 E3 IQ PIC
M20 Internet Router PIC Guide