
Multi-Service Access Device For Channelized Interfaces
Telecom Standard Product Data Sheet
Production
Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
Document ID: PMC-1990823, Issue 4
85
The pseudo-random or repetitive pattern can be inserted/extracted in the DS3 payload. It cannot
be inserted into the ATM cell or POS frame payload.
11.12 SONET/SDH PRBS Generator and Monitor (PRGM)
The SONET/SDH Pseudo-Random bit sequence Generator and Monitor (PRGM) block generates
and monitors an unframed 2
timeslots.
23
-1 payload test sequence on the ingress and egress TelecomBus bus
The PRGM can generate PRBS in an STS-1/3c/12c/48c (AU3/4/4—4c/4-16c) payload. The path
overhead column, the fixed stuff columns #2 to #4 in an STS-12c (AU-4-4c) payload, the fixed
stuff columns #2 to16 in an STS-48c (AU-4-16c) payload and the fixed stuff column #30 and #59
in an STS-1 (AU3) payload do not contain any PRBS data.
When processing a concatenated STS-48c (STM-16c) payload, 4 PRGMs are linked in a
master/slave configuration. The master PRGM co-ordinates the distributed PRBS generation
between itself and the slave PRGMs. Each PRGM generates one quarter of the complete PRBS
sequence. To ensure that the slave PRGMs are synchronized with the master PRGM, a signature
is continuously broadcasted by the master PRGM to allow the slave PRGMs to check their
relative states. A signature mis-match is flagged as an out-of-synch state by the slave PRGM. A
re-synchronization of the PRBS generation must be initiated by the master PRGM (under
software control).
The PRBS monitor of the PRGM block monitors the recovered payload data for the presence of
an unframed 2
random pattern. The PRGM declares synchronization when a sequence of 4 correct pseudo-
random patterns (bytes) are detected consecutively. Pattern errors are only counted when the
PRGM is in synchronization with the input sequence. When 3 consecutive pattern errors are
detected, the PRGM will fall out of synchronization and will continuously attempt to re-
synchronize to the input sequence until it is successful.
23
-1 test sequence and accumulates pattern errors detected based on this pseudo-
When processing a concatenated STS-48c (STM-16c) payload, the master PRGM and the slave
PRGMs independently monitor one quarter of the complete PRBS sequence. To ensure that the
slave PRGMs are synchronized with the master PRGM, the same signature matching will be
performed as described for the PRBS generation.
A maskable interrupt is activated to indicate any change in the synchronization status.
11.13 Receive Channel Assigner (RCAS-12)
The Receive Channel Assigner is used to group STS-1/STM-0 system timeslots into channels and
transform the internal DS3 serial streams into byte-wide format for processing by the RTDP
block. Channel numbers are associated with the Utopia/POS interface RADR[5:0] values.