PM5362TUPP-PLUS
DATA SHEET
PMC-951010
ISSUE 6
SONET/SDH TRIBUTARY UNIT PAYLOAD PROCESSOR / PERFORMANCE MONITOR
incoming multiframe detector so that it can determine the incoming tributary
multiframe boundaries. The identification of specific tributaries allows the pointer
interpreter to be time-sliced across the mix of tributaries present in the incoming
data stream. The identification of the V1-V3 bytes of VTs, or TUs (or H1-H3 bytes
in the case of TU3s) allows the pointer interpreter to function.
8.3.3 Incoming Multiframe Detector
The multiframe alignment sequence in the path overhead H4 byte is monitored
for the bit patterns of 00, 01, 10, 11 in the two least significant bits. If an
unexpected value is detected, the primary multiframe will be kept, and a second
multiframe process will, in parallel, check for a phase shift. The primary process
will enter out of multiframe state (OOM). A new multiframe alignment is chosen,
and OOM state is exited when four consecutive correct multiframe patterns are
detected. Loss of multiframe (LOM) is declared after residing in the OOM state
at the ninth H4 byte without re-alignment. In counting to nine, the out of
sequence H4 byte that triggered the transition to the OOM state is counted as
the first. A new multiframe alignment is chosen, and LOM state is exited when
four consecutive correct multiframe patterns are detected. Changes in
multiframe alignments are detected and reported.
8.3.4 Pointer Interpreter
The pointer interpreter is a time-sliced state machine that can process up to 28
independent tributaries. The state vector is saved in RAM as directed by the
incoming timing generator. The pointer interpreter processes the incoming
tributary pointers such that all bytes within the tributary synchronous payload
envelope can be identified and written into the unique payload first-in first-out
buffer for the tributary in question. A marker that tags the V5 byte (or J1 byte in
the case of a TU3) is passed through the payload buffer. The incoming timing
generator directs the pointer interpreter to the correct payload buffer for the
tributary being processed.
The pointer interpreter processes the incoming pointers (V1/V2 or H1/H2 in TU3
mode) as specified in the references. The pointer value is used to determine the
location of the tributary path overhead byte (V5 or J1 in TU3) in the incoming
TUG3 or STS-1 (AU3) stream. The algorithm can be modeled by a finite state
machine. Within the pointer interpretation algorithm three states are defined (as
shown in Figure 1):
NORM_state (NORM)
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