Cisco 2600 Series Operation Manual page 52

Fast Ethernet PRI Module LEDs
Table 5-2
LED
REMOTE ALARM
LOCAL ALARM
LOOPBACK
CARRIER
DETECT
5-14 Cisco Network Modules Hardware Installation Guide
ISDN PRI LEDs
Color Meaning
Yellow A remote source is indicating an error at its end of the
connection.
Yellow Incoming signal shows loss of signal, loss of frame, or
excessive errors.
Yellow Line or local loopback state is set or detected.
Green DS-1 carrier to the network is detected.