PM5380-BI PMC-Sierra, Inc., PM5380-BI Datasheet - Page 85

• Manufacturer Part Number: PM5380-BI
• Description: Network Interface, SATURN User Network Interface (8x155) Telecom Standard Product
• Manufacturer: PMC-Sierra, Inc.

Proprietary and Confidential to PMC-Sierra, Inc., and for its customers’ internal use.
Document No.: PMC- 2010299, Issue 2
10.13.3
10.13.4
10.13.5
Figure 9 CRC Generator
An error insertion mechanism is provided for system diagnosis purposes. Error insertion is
performed by inverting the resulting FCS value, before transmission. This should cause an FCS
Error at the far end.
Byte Stuffing
The POS Frame generator provides transparency by performing byte stuffing. This operation is
done after the FCS calculation. Two characters are being escaped, the Flag Sequence (0x7E)
and the Escape Character itself (0x7D). When a character is being escaped, it is XORed with
0x20 before transmission and preceded by the Control Escape (0x7D) character.
Table 4 HDLC Byte Sequences
Data Scrambling
The Scrambler will optionally scramble the whole packet data, including the FCS and the flags.
Scrambling is performed after the POS frame is formed using a parallel implementation of the
self-synchronous scrambler polynomial, x 43 +1. On reset, the scrambler is set to all ones to
ensure scrambling on start-up. The scrambler may optionally be completely disabled. Data
scrambling can provide for a more robust system preventing the injection of hostile patterns into
the data stream.
SONET/SDH Framer
The SONET/SDH Framer gaps the POS frames in order to insert the SONET/SDH framing and
overhead bytes (Section/Line Overhead and Path Overhead). The framer uses framing
alignment information provided by the TPOP TSB to perform its function. The TXFP does not
set any SONET/SDH overhead bytes.
Data Value
0x7E (Flag Sequence)
0x7D (Control Escape)
HDLC Abort Sequence
D
0
LSB
g
+
1
D
1
Parity Check Digits
Sequence
0x7D 0x5E
0x7D 0x5D
0x7D 0x7E
g
+
S/UNI®-8x155 ASSP Telecom Standard Product Data Sheet
2
. . .
g
+
n-1
D
n-1
MSB
+
Message
Released
85