
PM7346 S/UNI-QJET
DATASHEET
PMC-960835
ISSUE 6
SATURN QUAD USER NETWORK INTERFACE FOR J2, E3, T3
PMC-SIERRA, INC. PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA INC., AND ITS CUSTOMERS’ INTERNAL USE
310
12.4 DS3 Frame Format
The S/UNI-QJET supports both M23 and C-bit parity DS3 framing formats. This
format can be extended to support direct byte mapping or PLCP mapping of ATM
cells. An overview of the DS3 frame format is shown in Figure 16.
Figure 16
- DS3 Frame Structure
X1
Payload
F1
Payload
C1
Payload
F2
Payload
C2
Payload
F3
Payload
C3
Payload
F4
Payload
X2
Payload
F1
Payload
C1
Payload
F2
Payload
C2
Payload
F3
Payload
C3
Payload
F4
Payload
P1
Payload
F1
Payload
C1
Payload
F2
Payload
C2
Payload
F3
Payload
C3
Payload
F4
Payload
P2
Payload
F1
Payload
C1
Payload
F2
Payload
C2
Payload
F3
Payload
C3
Payload
F4
Payload
M1
Payload
F1
Payload
C1
Payload
F2
Payload
C2
Payload
F3
Payload
C3
Payload
F4
Payload
M2
Payload
F1
Payload
C1
Payload
F2
Payload
C2
Payload
F3
Payload
C3
Payload
F4
Payload
M3
Payload
F1
Payload
C1
Payload
F2
Payload
C2
Payload
F3
Payload
C3
Payload
F4
Payload
680 bits (8 blocks of 84+1 bits)
84 bits
1
M-subframe
2
3
4
5
6
7
The DS3 receiver decodes a B3ZS-encoded signal and provides indications of
line code violations (LCVs). The B3ZS decoding algorithm and the LCV
definition are software selectable.
While in-frame, the DS3 receiver continuously checks for line code violations, M-
bit or F-bit framing bit errors, and P-bit parity errors. When C-bit parity mode is
selected, both C-bit parity errors and far end block errors are accumulated.
When the C-bit parity framing format is detected, both the far end alarm and
control (FEAC) channel and the path maintenance data link are extracted. HDLC
messages in the Path Maintenance Data Link are received by an internal data
link receiver.
The DS3 transmitter allows for the insertion of the overhead bits into a DS3 bit
stream and produces a B3ZS-encoded signal. Status signals such as far end
receive failure (FERF), the alarm indication signal (AIS) and the idle signal can
be inserted when the transmission of these signals is enabled
The processing of the overhead bits in the DS3 frame is described in the
following table. In the transmit direction, the overhead bits can be inserted on a
bit-by-bit basis from a user supplied data stream using the TOH[x], TOHINS[x],