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Transport aspects 2

The OPUk contains one instance of the 2 147 483 647-bit pseudo-random test sequence. The OPUCn
contains n instances of the 2 147 483 647-bit pseudo-random test sequence, numbered 1 to n.
NOTE – This PRBS test pattern is not intended to be deployed for stress testing of the physical interface.

17.6 Mapping of a non-specific client bit stream into OPUk

In addition to the mappings of specific client signals as specified in the other subclauses of this clause, a
non-specific client mapping into OPUk is specified. Any (set of) client signal(s), which after encapsulation
into a continuous bit stream with a bit rate of the OPUk payload, can be mapped into the OPUk payload
(see Figure 17-10). The bit stream must be synchronous with the OPUk signal. Any justification must be
included in the continuous bit stream creation process. The continuous bit stream must be scrambled
before mapping into the OPUk payload.

Figure 17-10  OPUk frame structure for the mapping of a synchronous constant bit stream

The OPUk overhead for the mapping consists of a payload structure identifier (PSI) including the payload
type (PT) and 255 bytes reserved for future international standardization (RES), and seven bytes for client-
specific (CS) purposes. The definition of these CS overhead bytes is performed within the encapsulation
process specification.
The OPUk payload for this non-specific mapping consists of 4  3808 bytes.

17.6.1 Mapping bit stream with octet timing into OPUk
If octet timing is available, each octet of the incoming data stream will be mapped into a data byte (octet)
of the OPUk payload.

17.6.2 Mapping bit stream without octet timing into OPUk
If octet timing is not available, groups of eight successive bits (not necessarily an octet) of the incoming
data stream will be mapped into a data byte (octet) of the OPUk payload.

17.7 Mapping of other constant bit-rate signals with justification into OPUk

Mapping of other CBR client signals (with up to 100 ppm bit-rate tolerance) into an OPUk (k = 0, 1, 2, 3, 4)
is performed by the generic mapping procedure as specified in Annex D.

During a signal fail condition of the incoming CBR client signal (e.g., in the case of a loss of input signal), this
failed incoming signal is replaced by the appropriate replacement signal as defined in the clauses hereafter.

During a signal fail condition of the incoming ODUk/OPUk signal (e.g., in the case of an ODUk-AIS, ODUk-
LCK, ODUk-OCI condition), the failed client signal is replaced by the appropriate replacement signal as
defined in the clauses hereafter.

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