
XRT86L30
SINGLE T1/E1/J1 FRAMER/LIU COMBO
PRELIMINARY
The CPE, upon detecting the incoming AIS16 signal, will generate a CAS Multi-frame Yellow Alarm to the Re-
peater 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
REV. P1.0.1
240
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" pat-
tern.
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 in-
termediate 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 re-
covery 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).
F
IGURE
102. G
ENERATION
OF
CAS M
ULTI
-
FRAME
Y
ELLOW
A
LARM
BY
THE
CPE
UPON
DETECTION
OF
“AIS16”
PATTERN
SENT
BY
THE
R
EPEATER
E1 Receive
Framer Block
E1 Transmit
Framer Block
E1 Receive
Framer Block
E1 Transmit
Framer Block
E1
Transmit
Section
E1
Transmit
Section
E1
Receive
Section
E1
Receive
Section
CO
Repeater
CPE
The timeslot 16
of an E1 line is
iimpaired
Repeater generates
CAS Multi-frame
Yellow Alarm to CO
Repeater
generates
AIS16 to CPE
AIS16
CAS Multi-
frame Yellow
Alarm
CPE detects AIS16
and generates CAS
Multi-frame Yellow
Alarm to Repeater
CAS Multi-
frame Yellow
Alarm