Page 1172 - 5G Basics - Core Network Aspects

2 Transport aspects

NOTE – The NJO byte will always carry a stuff byte, the PJO byte will always carry a data (D) byte and the JC bytes will
always carry the all-0s pattern.

..... Column # .....
.....
15 16 17 1904 1905 1920 1921 3824
1 RES JC 118 16D 16FS 119 16D
Row # 2 RES JC 118 16D 16FS 119 16D
118 16D
119 16D
3 RES
16FS
JC
4 PSI NJO PJO 15D + 117 16D 16FS 119 16D
G.709-Y.1331(12)_F17-5
Figure 17-5  Mapping of a CBR10G3 signal into OPU2e

17.3 Blank clause
This clause is intentionally left blank.

17.4 Mapping of GFP frames into OPUk (k=0,1,2,3,4,flex)

The mapping of generic framing procedure (GFP) frames is performed by aligning the byte structure of
every GFP frame with the byte structure of the OPUk payload (see Figure 17-6). Since the GFP frames are of
variable length (the mapping does not impose any restrictions on the maximum frame length), a frame may
cross the OPUk (k=0,1,2,3,4,flex) frame boundary.

Figure 17-6  OPUk frame structure and mapping of GFP frames into OPUk

GFP frames arrive as a continuous bit stream with a capacity that is identical to the OPUk payload area, due
to the insertion of idle frames at the GFP encapsulation stage. The GFP frame stream is scrambled during
encapsulation.
NOTE 1 – There is no rate adaptation or scrambling required at the mapping stage; this is performed by the GFP
encapsulation process.
The OPUk overhead for the GFP mapping consists of a payload structure identifier (PSI) including the
payload type (PT), a client signal fail (CSF) indicator and 254 bytes plus 7 bits reserved for future
international standardization (RES), and seven bytes reserved for future international standardization (RES).
The CSF indicator should be used only for Ethernet private line type 1 services; for other packet clients the
CSF bit is fixed to 0.
The OPUk payload for the GFP mapping consists of 4 × 3808 bytes.
NOTE 2 – The OPUflex(GFP) bit rate may be any configured bit rate as specified in Tables 7-3 and 7-8.

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