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Transport aspects 2

Table 11-23 – Diagnostic responses sent by the FTU

Length
Name Byte Content
(bytes)
Self-test acknowledgement 3 2 0116 (Note)
(FTU-R only)
3 One byte for the minimum time in seconds the FTU-O
shall wait before requesting the self-test result, encoded
as an unsigned integer.

ACK 2 2 8016 (Note)
(FTU-O and FTU-R)
NOTE – All other values for byte 2 are reserved by ITU-T.

A diagnostic command may be sent at any time during showtime, including immediately following the end
of the initialization procedure. In all cases, reception of a diagnostic command shall be acknowledged to the
initiator (by an ACK or by a self-test acknowledgement response).
NOTE – A negative acknowledgement (NACK) is not used for diagnostic commands.

11.2.2.6.1 Perform self-test
Upon reception of the perform self-test command, the FTU-R shall respond with a self-test
acknowledgement, which indicates the minimum amount of time that the FTU-O shall wait before
requesting the results of the self-test. Further, the FTU-R shall perform the self-test and generate the
self-test result. The self-test procedure is vendor discretionary, but it shall not interfere with the functions
of the FTU-R, shall not impact the status of the connection and its duration shall not exceed 255 s. The
FTU-R shall obtain and store result of the self-test within the number of seconds indicated in the self-test
acknowledgement response. The indicated amount of time shall be an integer between one and 255 s. A
coded value of zero is reserved for future use.
The self-test results may be accessed using the inventory command defined in clause 11.2.2.10. The length
of the self-test results shall be four bytes. The first byte (including the MSB) shall be 0016 if the self-test
passed and 0116 if it failed. The meaning of failure is vendor discretionary. The contents of the three other
bytes are vendor discretionary.

11.2.2.6.2 Update test parameters
Upon reception of the update test parameters command, the requested FTU shall send the ACK response
and update the test parameter set defined in clause 11.4.1. All test parameters that can be updated during
the showtime shall be updated and stored within 10 s after the request is received. Upon reception of the
ACK response, the requesting FTU shall wait at least 10 s before sending the PMD test parameter read
commands defined in clause 11.2.2.13 to access the test parameter values defined in clause 11.4.1.

After the update test parameters command has been received, the test parameter values relating to the
most recent initialization shall no longer be accessible. They may be discarded by the responding FTU
immediately upon reception of the update test parameter command.

11.2.2.6.3 Start/end RTX_TESTMODE
A special test mode is defined for accelerated testing of the MTBE (see clause 9.8.3.1.2). A diagnostic
command is defined to enter or leave the mode during the showtime. Upon reception of the enter
RTX_TESTMODE command, the FTU-R shall acknowledge it with an ACK response. Afterwards, the FTU-R
shall acknowledge all received DTUs in the downstream direction and shall stop retransmitting any DTU
upstream. Upon reception of the end RTX_TESTMODE command, the FTU-R shall resume the normal
behaviour of retransmission.

11.2.2.6.4 Start/end TPS_TESTMODE

A special test mode is defined for accelerated testing of the MTBE (see clause 9.8.3.1.2). A diagnostic
command is defined to enter or leave this mode during the showtime. Upon reception of the enter

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