PM7345 datasheet(73/306 Pages) PMC

73 / 306 page

PM7345 S/UNI-PDH

DATA SHEET

PMC-931011

ISSUE 6

SATURN USER-NETWORK INTERFACE

PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE

9.18 TTB Trail Trace Buffer

The Trail Trace Buffer (TTB) extracts and sources the trail trace message carried in

the TR byte of the G.832 E3 stream. The message is used by the OS to prevent

delivery of traffic from the wrong source and is 16 bytes in length. The 16-byte

message is framed by the PTI Multiframe Alignment Signal (TMFAS = 'b10000000

00000000). One bit of the TMFAS is placed in the most significant bit of each

message byte. In the receive direction, the trail trace message is extracted from the

serial overhead stream output by the E3-FRMR. The extracted message is stored in

the internal RAM for review by an external microprocessor. By default, the TTB will

write the byte of a 16-byte message with its most significant bit set high to the first

location in the RAM. The extracted trail trace message is checked for consistency

between consecutive multiframes. A message received unchanged three or five

times (programmable) is accepted for comparison with the copy previously written

into the internal RAM by the external microprocessor. Alarms are raised to indicate

reception of unstable and mismatched messages. In the transmit direction, the TTB

sources the trail trace message from the internal RAM for insertion into the TR byte

by the E3-TRAN.

The TTB also extracts the Payload Type label carried in the MA byte of the G.832 E3

stream. The label is used to ensure that the adaptation function at the trail

termination sink is compatible with the adaptation function at the trail termination

source. The Payload Type label is check for consistency between consecutive

multiframes. A Payload Type label received unchanged for five frames is accepted

for comparison with the copy previously written into the TTB by the external

microprocessor. Alarms are raised to indicate reception of unstable and

mismatched Payload Type label bits.

9.19 Microprocessor Interface

The Microprocessor Interface (MPIF) Block serves as the physical interface between

the microprocessor and the internal blocks. The MPIF Block provides functions such

as data bus buffering and address decoding. The MPIF Block allows for device level

configuration of each block of the S/UNI-PDH device.

PM7345 Datasheet(PDF) 73 Page - PMC-Sierra, Inc