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Transport aspects 2

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PSI[2] ODTU type Tributary Port # TS1
PSI[3] ODTU type Tributary Port # TS2
PSI[4] ODTU type Tributary Port # TS3
PSI[5] ODTU type Tributary Port # TS4
PSI[6] ODTU type Tributary Port # TS5
: : : :
: : : :

PSI[33] ODTU type Tributary Port # TS32

Figure 19-20A – OPU3 MSI coding – Payload type 21

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PSI[1+ i] ODTU type Tributary Port # TS #i

00: ODTU13 00 0000: Tributary Port 1
01: ODTU23 00 0001: Tributary Port 2
10: ODTU3.ts 00 0010: Tributary Port 3
11: Unallocated 00 0011: Tributary Port 4
:
01 1111: Tributary Port 32

Figure 19-20B – OPU3 MSI coding – Payload type 21

19.4.2 OPUk payload structure identifier reserved overhead (RES)

253 (OPU1), 251 or 247 (OPU2), 239 or 223 (OPU3) and 175 (OPU4) bytes are reserved in the OPUk PSI for
future international standardization. These bytes are located in PSI[1] and PSI[4] (OPU1), PSI[6] or PSI[10]
(OPU2), PSI[18] or PSI[34] (OPU3), PSI[82] (OPU4) to PSI[255] of the OPUk overhead. These bytes are set to
all-0s.
19.4.3 OPUk multiplex justification overhead (JOH)

Two mapping procedures are used for the mapping of ODUj: either the asynchronous mapping procedure
(AMP) or generic mapping procedure (GMP) into ODTUjk or ODTUk.ts, respectively. AMP uses ODUj and
OPUk specific fixed stuff and justification opportunity definitions (ODTUjk). GMP uses ODUj and OPUk
independent stuff and justification opportunity definitions (ODTUk.ts). Stuff locations within an ODTUk.ts
are determined by means of a formula which is specified in clause 19.4.3.2.

19.4.3.1 Asynchronous mapping procedures (AMP)

The justification overhead (JOH) located in column 16 of the OPUk (k=1,2,3) as indicated in Figures 19-14A
and 19-14B consists of three justification control (JC) bytes and one negative justification opportunity
(NJO) byte. The three JC bytes are located in rows 1, 2 and 3. The NJO byte is located in row 4.

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