PM5364 pmc-sierra, PM5364 Datasheet - Page 254

• Manufacturer Part Number: PM5364
• Description: Tupp 2488 Assp Telecom Standard
• Manufacturer: pmc-sierra

14.6
Proprietary and Confidential to PMC-Sierra, Inc., and for its customers’ internal use.
Document No.: PMC-2011334, Issue 7
Tributary Path Overhead and Serial Alarm Timing
This section describes Tributary Serial Path Overhead and Alarm Output Timing per STS-
12/STM-4 slice.
The Tributary Path Overhead and Alarm (TPOH) port outputs the entire path overhead and
alarm indications for all tributaries for external processing (to a maximum of 336 per STS-
12/SDH-4 data stream). The TPOH port includes device pin TPOH[4:1], TPOHEN[4:1],
TPOHFP[4:1] and TRAD[4:1].
All signals on the TPOH port are referenced to the 77.76 MHz reference clock (REFCLK), and
they are updated on the rising edge of REFCLK.
The TPOHFP signal provides synchronization between the TPOH port and the transport frame.
It asserts high for 1 REFCLK clock cycle for every 250 µs interval, and it identifies the most
significant bit of the V5 or J1 byte for the first tributary on TPOH. Two TPOHFP frame pulses
are asserted in a 500 µs multiframe to denote the overhead transmission of 2 entire tributaries
(up to 336 timeslots).
During the extraction, the tributary path overhead bytes (V5, J2, Z6/N2, and Z7/K4 or J1, B3,
C2, G1, F2, H4, F3, K3 and N1 for the TU3 tributary) are extracted serially from the most
significant to the least significant bit through the TPOH signal. Since the tributary path
overhead bytes are output 2 times per 500 µs multiframe, in order to distinguish the first
presentation of an overhead byte from subsequent repeated presentations, TPOHEN is used. If
TPOHEN is asserted high, the path overhead byte on TPOH is new, and if TPOHEN is asserted
low, the path overhead byte is repeated.
Timeslot assignment on TPOH is unrelated to the tributary group configuration. The timeslots
for 4 tributaries are always reserved for any TUG2 even if it is configured for TU12, TU2 or
VT3. Hence, 336 timeslots are always available on the TPOH. At timeslots devoted to non-
existent tributaries; for example, tributary 2, 3 and 4 of a TUG2 configured for TU2, TPOH and
TPOHEN will set low.
The tributary path overhead output sequence on TPOH is arranged in the same order as on the
incoming STS-12/STM-4 data stream. Each STS-12/STM-4 data stream can contain up to 336
tributaries. Table 47 summarizes the completed sequence. The first path overhead output on
TPOH is from tributary STM-1#1, TUG3#1,TUG2#1, TU#1. The second path overhead output
is from tributary STM-1#2, TUG3#1,TUG2#1, TU#1. The last path overhead output is from
tributary STM-1#4, TUG3#3, TUG2#7, TU#4. The completed sequence is repeatedly output on
TPOH every 250 µs.
TUPP™ 2488 ASSP Telecom Standard Product Data Sheet
Released
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