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PRELIMINARY
DS3 UNI FOR ATM
XRT7245
REV. 1.03
267
7.3.2.6
The “Data Path Integrity” check is a test that is
continually run in order to verify that the connections
throughout the “ATM Layer” entity (e.g., from the
Receive UTOPIA Interface of the “source” UNI to the
Transmit UTOPIA Interface of the “destination” UNI)
are functioning properly.
The manner in which the “Data Path Integrity Check”
is employed is as follows. After an incoming cell has
passed through the cell delineation, HEC byte verifi-
cation, idle cell filtering and user cell filtering process,
it will be written to the Rx FIFO, within the Receive
UTOPIA Interface Block. However, prior to being writ-
ten into the Rx FIFO, the “Data Path Integrity Test”
pattern will be written into the 5th octet (overwriting
the HEC byte) of the “outbound” cell. This “Data Path
Integrity Test” pattern is typically of the value “55h”,
for each outbound cell. However, it can also be
configured to be an alternating pattern of “55h” and
AAh” (alternating values with each cell).
Data Path Integrity Check
The Transmit Cell Processor, within the “destination”
UNI will perform a check of the 5th byte of all cells
that it reads from the Tx FIFO; prior to computing and
overwriting this byte with the HEC byte. For more
information on how the Transmit Cell Processor
andles the “Data Path Integrity Check” test patterns,
please see section 6.2.2.6.
The Receive Cell Processor’s Handling of the
Data Path Integrity Test pattern
The user has a variety of options, when it comes to
configuring the Receive Cell Processor to support
the Data Path Integrity Test. First of all, the user can
decide whether or not he/she wishes to even transmit
a Data Path Integrity Test pattern, via the outbound
cell; or just allow the outbound cell with the HEC byte
to be written to the Rx FIFO. The user can configure
the Receive Cell Processor per his/her choice, by
writing the appropriate value into bit 5 (RDPChk
Pattern Enable) within the “Rx CP Configuration
Register (Address = 4Ch) as depicted below.
Writing a “1” to this bit-field configures the Receive
Cell Processor to write the “Data Path Integrity Test”
pattern into the 5th octet of each “outbound” cell,
prior to transmittal to the RxFIFO. Conversely, writing
a “0” to this bit-field configures the Receive Cell
Processor to write the cell, with the HEC byte, into
the RxFIFO.
Next, the Receive Cell Processor also allows the user
to choose between two possible Data Path Integrity
Test patterns. The user can configure his/her selection
by writing the appropriate value to Bit 6 (RDPChk
Pattern) within the “Rx CP Configuration” Register
(Address = 4Ch). Writing a “1” to this bit-field config-
ures the Receive Cell Processor to write a “55h” into
the 5th octet of each “outbound” cell, prior to it being
written into the Rx FIFO. Conversely, writing a “0” to
this bit-field configures the Receive Cell Processor to
write an alternating pattern of “55h” or “AAh”, into the
5th octet of each “outbound” cell, prior to it being writ-
ten into the RxFIFO. The Receive Cell Processor will
alternate between each of these two patterns with
each “outbound” cell.
Note:
The contents of Bit 6 of the Rx CP Configuration
Register, is ignored if Bit 5 is set to “0”.
RxCP Configuration Register (Address = 4Ch)
B
IT
7
B
IT
6
B
IT
5
B
IT
4
B
IT
3
B
IT
2
B
IT
1
B
IT
0
RxLCD
RDPChk
Pattern
RDPChk
Pattern
Enable
Idle Cell
Discard
OAM Check
Bit
De-Scramble
Enable
RxCoset
Enable
HEC Error
Ignore
RO
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
x
x
x
x
x
x
x
RxCP Configuration Register (Address = 4Ch)
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
RxLCD
RDPChk
Pattern
RDPChk
Pattern Enable
Idle Cell
Discard
OAM Check
Bit
De-Scramble
Enable
RxCoset
Enable
HEC Error
Ignore
RO
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
x
x
x
x
x
x
x