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DS3171/DS3172/DS3173/DS3174
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10.6 DS3/E3 Framer / Formatter
10.6.1 General Description
The Receive DS3/E3 Framer receives a unipolar DS3/E3 signal, determines frame alignment and extracts the
DS3/E3 overhead in the receive direction. The Transmit DS3/E3 Formatter receives a DS3/E3 payload, generates
framing, inserts DS3/E3 overhead, and outputs a unipolar DS3/E3 signal in the transmit direction.
The Receive DS3/E3 Framer receives a DS3/E3 signal from the Receive LIU or RDATn (or RPOSn and RNEGn),
determines the frame alignment, extracts the DS3/E3 overhead, and outputs the payload with frame and overhead
The Transmit DS3/E3 Formatter receives a DS3/E3 payload on TSERn, generates a DS3/E3 frame, optionally
inserts DS3/E3 overhead, and transmits the DS3/E3 signal.
Refer to
for the location of the DS3/E3 Framer/Formatter blocks in the DS3174, 3, 2, 1 devices.
Figure 10-13. Framer Detailed Block Diagram
DS3/E3
Transmit
LIU
IEEE P1149.1
JTAG Test
Access Port
Microprocessor
Interface
HDLC
FEAC
LLB
DL
B
DS3 / E3
Transmit
Formatter
DS3 / E3
Receive
Framer
Trail
Trace
Buffer
DS3/E3
Receive
LIU
TAIS
TUA1
Clock Rate
Adapter
TX BERT
RX BERT
PLB
AL
B
UA1
GEN
B3ZS/
HDB3
Encoder
B3ZS/
HDB3
Decoder
10.6.2 Features
10.6.2.1 Transmit Formatter
•
Programmable DS3 or E3 formatter
– Accepts a DS3 (M23 or C-bit) or E3 (G.751 or G.832) signal and
performs DS3/E3 overhead generation.
•
Arbitrary framing format support
– Generates a signal with an arbitrary framing format. The line
overhead/stuff periods are added into the data stream using an overhead mask signal.
•
Generates alarms and errors
– DS3 alarm conditions (AIS, RDI, and Idle) and errors (framing, parity, and
FEBE), or E3 alarm conditions (AIS and RDI/RAI) and errors (framing, parity, and REI) can be inserted into the
outgoing data stream.
•
Externally controlled serial DS3/E3 overhead insertion port
– Can insert all DS3 or E3 overhead via a
serial interface. DS3/E3 overhead insertion is fully controlled via the serial overhead interface.
•
HDLC overhead insertion
– An HDLC channel can be inserted into the DS3 or E3 data stream.
•
FEAC insertion
– A FEAC channel can be inserted into the DS3 or E3 data stream.
•
Trail Trace insertion
– Inputs and inserts the G.832 E3 TR byte.