Page 1230 - 5G Basics - Core Network Aspects

2 Transport aspects

NOTE – The PJO2 field will always carry an information byte.

Figure 19-26 – Mapping of ODU0 in OPU1 TS1

19.6 Mapping of ODUj into ODTUk.ts

The mapping of ODUj (j = 0, 1, 2, 2e, 3, flex) signals (with up to 100 ppm bit-rate tolerance) into the
ODTUk.ts (k = 2,3,4; ts = M) signal is performed by means of a generic mapping procedure as specified in
Annex D.
The OPUk and therefore the ODTUk.ts (k = 2,3,4) signals are created from a locally generated clock (within
the limits specified in Table 7-3), which is independent of the ODUj client signal.

The ODUj signal is extended with a frame alignment overhead as specified in clauses 15.6.2.1 and 15.6.2.2
and an all-0s pattern in the OTUj overhead field (see Figure 19-22).

The extended ODUj signal is adapted to the locally generated OPUk/ODTUk.ts clock by means of a generic
mapping procedure (GMP) as specified in Annex D. The value of n in cn and Cn(t) and CnD(t) is specified in
Annex D. The value of M is the number of tributary slots occupied by the ODUj; ODTUk.ts = ODTUk.M.
A group of 'M' successive extended ODUj bytes is mapped into a group of 'M' successive ODTUk.M bytes.

The generic mapping process generates for the case of ODUj (j = 0,1,2,2e,3,flex) signals once per ODTUk.M
multiframe the Cm(t) and CnD(t) information according to Annex D and encodes this information in the
ODTUk.ts justification control overhead JC1/JC2/JC3 and JC4/JC5/JC6. The de-mapping process decodes
Cm(t) and CnD(t) from JC1/JC2/JC3 and JC4/JC5/JC6 and interprets Cm(t) and CnD(t) according to Annex D.
CRC-8 shall be used to protect against an error in JC1,JC2,JC3 signals. CRC-5 shall be used to protect against
an error in JC4,JC5,JC6 signals.

During a signal fail condition of the incoming ODUj signal, this failed incoming signal will contain the ODUj-
AIS signal as specified in clause 16.5.1. This ODUj-AIS is then mapped into the ODTUk.M.

For the case where the ODUj is received from the output of a fabric (ODU connection function), the
incoming signal may contain (in the case of an open matrix connection) the ODUj-OCI signal as specified
in clause 16.5.2. This ODUj-OCI signal is then mapped into the ODTUk.M.
NOTE 1 – Not all equipment will have a real connection function (i.e., switch fabric) implemented; instead, the
presence/absence of tributary interface port units represents the presence/absence of a matrix connection. If such a
unit is intentionally absent (i.e., not installed), the associated ODTUk.M signals should carry an ODUj-OCI signal. If such
a unit is installed but temporarily removed as part of a repair action, the associated ODTUk.M signal should carry an
ODUj-AIS signal.

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