S/UNI®-JET Data Sheet
Released
Figure 38 Receive DS3 Overhead
DS3 M-frame Period
ROHFP
ROHCLK
ROHCLK
ROH
X1
Unused
C1 Unused
C2 Unused
C3
ROHFP
The Receive DS3 Overhead diagram (Figure 38) shows the extraction of the DS3 overhead bits
on the ROH output, along with overhead clock (ROHCLK), and
M-frame position indicator (ROHFP). The DS3 M-frame can be divided into seven M-subframes,
with each subframe containing eight overhead bits. The table below illustrates the overhead bit
order on ROH:
Table 44 DS3 Receive Overhead Bits
M-subframe
DS3 Overhead Bits
1
X
2
N/U
3
C
4
N/U
5
C
6
N/U
7
C
8
N/U
1
2
3
4
5
6
7
1
2
1
2
1
2
3
1
1
1
1
1
1
1
2
2
2
2
2
2
2
3
3
3
3
3
3
3
X
P
P
N/U
N/U
N/U
N/U
N/U
N/U
C
C
C
C
C
C
N/U
N/U
N/U
N/U
N/U
N/U
C
C
C
C
C
C
N/U
N/U
N/U
N/U
N/U
N/U
C
C
C
C
C
C
N/U
N/U
N/U
N/U
N/U
N/U
M
M
M
The DS3 framing bits (F-bits) are not extracted on the overhead port. The bit positions
corresponding to the F-bits in the extracted stream are marked N/U in the above table. The ROH
stream is invalid when the DS3 frame alignment is lost.
Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
Document ID: PMC-1990267, Issue 3
299
PMC [ PMC-SIERRA, INC ]
