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S/UNI-JET Data Sheet
Released
Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
Document ID: PMC-1990267, Issue 3
263
The DS1 PLCP frame provides the transmission of 10 ATM cells every 3 ms. The PLCP frame is
octet aligned to the framing bit in the DS1 frame; there is no relationship between the start of the
PLCP frame, and the start of the DS1 frame. A trailer is inserted at the end of each PLCP frame.
The number of octets inserted is always six, and cannot be varied.
Figure 10 G.751 E3 PLCP Frame Format
A1
A2
P8
Z3
A1
A2
P7
Z2
A1
A2
P6
Z1
A1
A2
P5
F1
A1
A2
P4
B1
A1
A2
P3
G1
A1
A2
P2
M2
A1
A2
P1
M1
A1
A2
P0
C1
Trailer
17,18,19,20, or 21
octets
ATM Cell
ATM Cell
ATM Cell
ATM Cell
ATM Cell
ATM Cell
ATM Cell
ATM Cell
ATM Cell
PLCP
Frame Rate
125 μs
53 octets
POH
Framing
(3 octets)
The G.751 E3 PLCP frame provides the transmission of 9 ATM cells every 125 μs. The PLCP
frame is octet aligned to the 16 overhead bits in the ITU-T Recommendation G.751 E3 frame;
there is no relationship between the start of the PLCP frame, and the start of the E3 frame. A
trailer is inserted at the end of each PLCP frame. The number of octets inserted is nominally 18,
19, or 20, and is based on the number of E3 overhead octets (4, 5, or 6) that have been inserted
during the PLCP frame period. The nominal octet stuffing can be varied by ±1 octet to allow the
E3 PLCP frame to be locked to an external 8 kHz reference. Thus the trailer can be 17, 18, 19, 20,
or 21 octets in length.