S/UNI®-8x155 ASSP Telecom Standard Product Data Sheet
Released
Note:
Sꢀ XX, YY are equal to anything except 0x00 or 0x01 and are not equal to each other.
10.15 SONET/SDH Section Trace Buffer (SSTB)
The SONET/SDH Section Trace Buffer (SSTB) block can handle both 64-byte CLLI messages
in SONET and 16-byte E.164 messages in SDH. This block operates similarly to the
SONET/SDH Path Trace Buffer (SPTB).
10.15.1Receive Trace Message Receiver
When TIMODE is low, the Trace Message Receiver (TMR) captures the received section trace
identifier message (J0 byte) into microprocessor readable register. It contains three pages of
trace message memory. They are the capture page, the accepted page and the expected page.
Section trace identifier data bytes from the receive stream are written into the capture page. The
expected identifier message is written by the microprocessor into the expected page.
On receipt of a trace identifier byte, it is written into next location in the capture page. The
received byte is compared with the data from the previous message in the capture page. An
identifier message is accepted if it is received unchanged three times, or optionally, five times.
The accepted message is then compared with the expected message. If the current message
differs from the previous message for eight consecutive messages, the received message is
declared unstable. The received message is declared stable when the received message passes
the persistency criterion (three or five identical receptions) for being accepted. An interrupt
may be optionally generated on entry to and exit from the unstable state.
The length of the section trace identifier message is selectable between 16 bytes and 64 bytes.
When programmed for 16 byte messages, the section trace buffer synchronizes to the byte with
the most significant bit set to high and places the byte at the first location in the capture page.
When programmed for 64 byte messages, the section trace buffer synchronizes to the trailing
carriage return (CR = 0DH), line feed (LF = 0AH) sequence and places the next byte at the head
of the capture page. This enables the section trace message to be appropriately aligned for
interpretation by the microprocessor. Synchronization may be disabled, in which case, the
memory acts as a circular buffer.
When TIMODE is high, a stable message is declared when forty eight of the same section trace
identifier message (J0) bytes are received. Once in the stable state, an unstable state is declared
when one or more errors are detected in three consecutive sixteen byte windows.
10.15.2Transmit Trace Buffer (TTB)
The TTB sources the 16-byte or 64-byte trace identifier message. The TTB contains one page
of transmit trace identifier message memory. Identifier message data bytes are written by the
microprocessor into the message buffer and inserted in the transmit stream. When the
microprocessor is updating the transmit page buffer, the TTB may be programmed to transmit
null characters to prevent transmission of partial messages.
Proprietary and Confidential to PMC-Sierra, Inc., and for its customers’ internal use.
Document No.: PMC- 2010299, Issue 2
88
PMC [ PMC-SIERRA, INC ]
