S/UNI®-JET Data Sheet
Released
Figure 51 Generic Transmit Stream
TICLK bit logic 0:
TIOHM
TICLK
TCLK
Overhead Placeholder Bits
TDATO
TOHM
Bit 4 Bit 5 Bit 6 Bit 7 Bit 8
Bit 5 Bit 6 Bit 7 Bit 8
Bit 1 Bit 2
Bit 3
ATM Cell
Octet n
ATM Cell
Octet n +1
TICLK bit logic 1:
TIOHM
TICLK
Overhead Placeholder Bits
TDATO
Bit 4 Bit 5
Bit 1 Bit 2 Bit 3
Bit 3 Bit 4 Bit 5 Bit 6
Bit 7
Bit 8
ATM Cell
ATM Cell
Octet n +1
Octet n
TOHM
The Generic Transmit Stream diagram (Figure 51) illustrates overhead indication positions when
interfacing to a non-PLCP based transmission system not supported by the SUNI-QJET. The
overhead bit placeholder positions are indicated using the TIOHM input. The ATM cells
presented in the TDATO transmit stream are held off to include the overhead placeholders. The
location of these placeholder positions is indicated by TOHM. A downstream framer inserts the
correct overhead information in the placeholder positions.
The delay between TIOHM and TOHM is dependent on the state of the TICLK bit of the S/UNI-
JET Transmit Configuration Register. If the TICLK bit is a logic zero, TOHM is updated on the
falling TCLK edge. TCLK is a flow-through version of TICLK and the propagation delay
between TICLK and TCLK may vary depending on specific configurations. If the TICLK bit is a
logic one, TOHM is presented on the fifth rising edge of TICLK after the rising edge which
samples TIOHM.
Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
Document ID: PMC-1990267, Issue 3
306
PMC [ PMC-SIERRA, INC ]
