ADTRAN Cable T1 ESF CSU ACE - Manual (Page 24)

Chapter 2. Physical Description
24 T1 ESF CSU Rackmount User Manual 61202066L1-1B
Table 2-1. Alarm Conditions
The alarm indication signal (AIS) is an all ones signal sent in place of the
received signal when the unit is in red alarm. The AIS signal is sent in the
same direction as the received alarm condition. If a red alarm condition
exists on the network side, AIS is transmitted toward the data terminal
equipment (DTE). If a red alarm exists on the DTE side, AIS is
transmitted toward the network. A yellow alarm is a fixed byte pattern
sent toward the origin of the red alarm. A red alarm is caused by out-of-
frame/loss-of-signal (OOF /LOS) conditions and involves an integration
process. Code violations (CVs) are cyclic redundancy check (CRC) errors
or bipolar violations (BPVs) in ESF mode or BPVs in SF mode.
Test Status (yellow)
The Test LED indicates that the Tl ESF CSU RM is in a test mode. The
test modes are local loopback, remote loopback, or test pattern generation.
During all of these test modes, the Test LED is On.
INDICATOR DEFINITION
LOS
AIS
OOF
YEL
CVs loss of signal
AIS received
out of frame
yellow alarm received
code violations received