Page 1220 - 5G Basics - Core Network Aspects

2 Transport aspects

1 2 3 4 5 6 7 8
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[7] ODTU type Tributary Port # TS6
PSI[8] ODTU type Tributary Port # TS7
PSI[9] ODTU type Tributary Port # TS8

Figure 19-19A – OPU2 MSI coding – Payload type 21

1 2 3 4 5 6 7 8

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

00: ODTU12 00 0000: Tributary Port 1
01: Reserved 00 0001: Tributary Port 2
10: ODTU2.ts 00 0010: Tributary Port 3
11: Unallocated 00 0011: Tributary Port 4
:
00 0111: Tributary Port 8

Figure 19-19B – OPU2 MSI coding – Payload type 21

19.4.1.6 OPU3 with 1.25G tributary slots (payload type 21) multiplex structure identifier (MSI)
For the thirty-two OPU3 1.25G tributary slots 32 bytes of the PSI (PSI[2] to PSI[33]) are used as MSI bytes as
shown in Figures 19-14B, 19-20A and 19-20B. The MSI indicates the ODTU content of each tributary slot of
an OPU. One byte is used for each tributary slot.

– The ODTU type in bits 1 and 2 indicates if the OPU3 1.25G TS is carrying an ODTU13, ODTU23 or
ODTU3.ts. The default ODTU type is 11 (unallocated); it is present when a tributary slot is not
allocated to carry an ODTU.
– The tributary port # in bits 3 to 8 indicates the port number of the ODTU that is being transported
in this TS; a flexible assignment of tributary ports to tributary slots is possible, ODTU13 tributary
ports are numbered 1 to 16, ODTU23 tributary ports are numbered 1 to 4 and ODTU3.ts tributary
ports are numbered 1 to 32. The value is set to all-0s when the ODTU type has the value 11
(tributary slot is unallocated).

1210