Page 1163 - 5G Basics - Core Network Aspects

Transport aspects 2

Table 15-9  Payload type code points

MSB LSB Hex code Interpretation
1 2 3 4 5 6 7 8 (Note 1)
0 1 1 0 0 1 1 0 66 Not available (Note 2)

1 0 0 0 x x x x 80-8F Reserved codes for proprietary use (Note 4)
1 1 1 1 1 1 0 1 FD NULL test signal mapping, see clause 17.5.1
1 1 1 1 1 1 1 0 FE PRBS test signal mapping, see clause 17.5.2
1 1 1 1 1 1 1 1 FF Not available (Note 2)
NOTE 1 – There are 200 spare codes left for future international standardization. Refer to Annex A of [ITU-T G.806] for the
procedure to obtain one of these codes for a new payload type.
NOTE 2 – These values are excluded from the set of available code points. These bit patterns are present in ODUk maintenance
signals or were used to represent client types that are no longer supported.
NOTE 3 – Value "01" is only to be used for experimental activities in cases where a mapping code is not defined in this table.
Refer to Annex A of [ITU-T G.806] for more information on the use of this code.
NOTE 4 – These 16 code values will not be subject to further standardization. Refer to Annex A of [ITU-T G.806] for more
information on the use of these codes.
NOTE 5 – Supplement 43 (2008) to the ITU-T G-series of Recommendations indicated that this mapping recommended using
payload type 87.
NOTE 6 – Equipment supporting ODTUk.ts for OPU2 or OPU3 must be backward compatible with equipment which supports only
the ODTUjk. ODTUk.ts capable equipment transmitting PT=21 which receives PT=20 from the far end shall revert to PT=20 and
operate in ODTUjk only mode. Refer to [ITU-T G.798] for the specification.
15.9.2.2 OPU mapping specific overhead

Seven bytes are reserved in the OPUk overhead for the mapping, concatenation and hitless adjustment
specific overhead. These bytes are located in rows 1 to 3, columns 15 and 16 and column 16 row 4. In
addition, 255 bytes in the PSI #1 and 256 byte in PSI #2 to #n are reserved for mapping and concatenation
specific purposes.
The use of these bytes depends on the specific client signal mapping (defined in clauses 17, 19 and 20) and
use of hitless adjustment of ODUflex(GFP) (see [ITU-T G.7044]).

16 Maintenance signals
An alarm indication signal (AIS) is a signal sent downstream as an indication that an upstream defect has
been detected. An AIS signal is generated in an adaptation sink function. An AIS signal is detected in a trail
termination sink function to suppress defects or failures that would otherwise be detected as a
consequence of the interruption of the transport of the original signal at an upstream point.

A forward defect indication (FDI) is a signal sent downstream as an indication that an upstream defect has
been detected. An FDI signal is generated in an adaptation sink function. An FDI signal is detected in a trail
termination sink function to suppress defects or failures that would otherwise be detected as a
consequence of the interruption of the transport of the original signal at an upstream point.
NOTE – AIS and FDI are similar signals. AIS is used as the term when the signal is in the digital domain. FDI is used as
the term when the signal is in the optical domain; FDI is transported as a non-associated overhead.
An open connection indication (OCI) is a signal sent downstream as an indication that upstream the signal is
not connected to a trail termination source. An OCI signal is generated in a connection function and output
by this connection function on each of its output connection points, which are not connected to one of its
input connection points. An OCI signal is detected in a trail termination sink function.
A locked (LCK) is a signal sent downstream as an indication that upstream the connection is "locked", and
no signal has passed through.

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