
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
316
12.7 J2 Frame Format
The S/UNI-QJET provides support for the G.704 and NTT J2 frame format. This
format can be extended to allow for direct byte mapping of ATM cells as specified
in G.804. The J2 frame format consists of 789 bits frames each 125 us long,
consisting of 96 bytes of payload, 2 reserved bytes, and 5 F-bits. The frames are
grouped into 4 frame multiframes as shown in Figure 19.
Figure 19
- J2 Frame Structure
TS1
TS2
TS3
TS4
TS95 TS96 TS97 TS98
1
1
0
0
m
TS1
TS2
TS3
TS4
TS95 TS96 TS97 TS98
1
0
1
0
0
TS1
TS2
TS3
TS4
TS95 TS96 TS97 TS98
x1
x2
x3
a
m
TS1
TS2
TS3
TS4
TS95 TS96 TS97 TS98
e1
e2
e3
e4
e5
125 uS
96 Octets of byte inter-
leaved payload
1-8
9-16
17-24
25-32
752-
760
761-
768
769-
776
777-
784
785
786
787
788
789
Bit #
Frame 1
Frame 2
Frame 3
Frame 4
The J2 framer decodes a unipolar or B8ZS encoded signal and frames to the
resulting 6,312 Kbit/s J2 bit stream. Once in frame, the J2 framer provides
indications of frame and multiframe boundaries and marks overhead bits, x-bits,
m-bits and reserved channels (TS97 and TS98). Indications of loss of signal,
bipolar violations, excessive zeroes, change of frame alignment, framing errors,
and CRC errors are provided and accumulated in internal counters.
The J2 transmitter inserts the overhead bits into a J2 bit stream and produces a
B8ZS-encoded signal. The J2 transmitter adheres to the framing format
specified in G.704 and NTT Technical Reference for High Speed Digital Leased
Circuit Services.
The processing of the overhead bits in the J2 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 using the TOH[x], TOHINS[x], TOHFP[x], and
TOHCLK[x] signals. In the receive direction, the overhead bits are brought out
serially on the ROH[x] data stream.