XRT86L30
REV. 1.0.1
SINGLE T1/E1/J1 FRAMER/LIU COMBO
The CPE, upon detecting the incoming AIS16 signal, will generate a CAS Multi-frame Yellow Alarm to the
Repeater to indicate the loss of CAS Multi-frame synchronization. Figure 102 below illustrates the CPE
sending a CAS Multi-frame Yellow Alarm back to the Repeater
FIGURE 102. GENERATION OF CAS MULTI
-FRAME
YELLOW
A
LARM BY THE CPE UPON DETECTION OF “AIS16”
PATTERN SENT BY THE
REPEATER
CPE detects AIS16
and generates CAS
Multi-frame Yellow
Alarm to Repeater
Repeater generates
CAS Multi-frame
Yellow Alarm to CO
CO
Repeater
CPE
CAS Multi-
frame Yellow
Alarm
CAS Multi-
frame Yellow
Alarm
E1
Transmit
Section
E1
Receive
Section
E1 Receive
Framer Block
E1 Receive
Framer Block
AIS16
E1
Receive
Section
E1
Transmit
Section
E1 Transmit
Framer Block
E1 Transmit
Framer Block
The timeslot 16
of an E1 line is
iimpaired
Repeater
generates
AIS16 to CPE
In summary, AIS or Blue Alarm is sent by a piece of E1 equipment downstream indicating that the incoming
signal from upstream is lost. Yellow Alarm is sent by a piece of E1 equipment upstream upon detection of Loss
of Signal, Loss of Frame or when it is receiving AIS.
Similarly, an "AIS16" pattern is sent by a piece of E1 equipment downstream indicating that the incoming data
link channel from upstream is damaged. The CAS Multi-frame Yellow Alarm is sent by a piece of E1 equipment
upstream upon detection of Loss of CAS Multi-frame synchronization or when it is receiving an "AIS16"
pattern.
12.5.1
How to configure the framer to transmit AIS
As we discussed in the previous section, Alarm Indication Signal (AIS) or Blue Alarm is transmitted by the
intermediate node to indicate that the equipment is still functioning but unable to offer services. It is an all ones
(except for framing bits) pattern which can be used by the equipment further down the line to maintain clock
recovery and timing synchronization.
The XRT86L30 framer can generate three types of AIS when it is running in E1 format:
•
•
•
Framed AIS
Unframed AIS
AIS16
Unframed AIS is an all ones pattern. If unframed AIS is sent, the equipment further down the line will be able to
maintain timing synchronization and be able to recover clock from the received AIS signal. However, due to the
lack of framing bits, the equipment farther down the line will not be able to maintain frame synchronization and
will declare Loss of Frame (LOF).
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EXAR [ EXAR CORPORATION ]
