3GPP 24.501 v20.0.0 — the document's own text

9.11.2.8 S-NSSAI

Taught in 4. Inside TS 24.501, the document at the centre (CT1 — the group that writes what your phone says, overview).

The purpose of the S-NSSAI information element is to identify a network slice.

The S-NSSAI information element is coded as shown in figure 9.11.2.8.1 and table 9.11.2.8.1.

The S-NSSAI is a type 4 information element with a minimum length of 3 octets and a maximum length of 10 octets.

8	7	6	5	4	3	2	1
S-NSSAI IEI	octet 1
Length of S-NSSAI contents	octet 2
SST	octet 3
SD	octet 4octet 6
Mapped HPLMN SST	octet 7*
Mapped HPLMN SD	octet 8octet 10

Figure 9.11.2.8.1: S-NSSAI information element

Table 9.11.2.8.1: S-NSSAI information element

Length of S-NSSAI contents (octet 2)

This field indicates the length of the included S-NSSAI contents, and it can have the following values. Depending on the value of the length field the following S-NSSAI contents are included:
Bits
8	7	6	5	4	3	2	1
0	0	0	0	0	0	0	1	SST
0	0	0	0	0	0	1	0	SST and mapped HPLMN SST
0	0	0	0	0	1	0	0	SST and SD
0	0	0	0	0	1	0	1	SST, SD and mapped HPLMN SST
0	0	0	0	1	0	0	0	SST, SD, mapped HPLMN SST and mapped HPLMN SD
All other values are reserved.
Slice/service type (SST) (octet 3)
This field contains the 8 bit SST value. The coding of the SST value part is defined in 3GPP TS 23.003 [4]. If this IE is included during the network slice-specific authentication and authorization procedure, this field contains the 8 bit SST value of an S-NSSAI in the S-NSSAI(s) of the HPLMN or the RSNPN.
Slice differentiator (SD) (octet 4 to octet 6)This field contains the 24 bit SD value. The coding of the SD value part is defined in 3GPP TS 23.003 [4]. If this IE is included during the network slice-specific authentication and authorization procedure, this field contains the 24 bit SD value of an S-NSSAI in the S-NSSAI(s) of the HPLMN or the RSNPN.
If the SST encoded in octet 3 is not associated with a valid SD value, and the sender needs to include a mapped HPLMN SST (octet 7) and a mapped HPLMN SD (octets 8 to 10), then the sender shall set the SD value (octets 4 to 6) to "no SD value associated with the SST".

mapped HPLMN Slice/service type (SST) (octet 7)
This field contains the 8 bit SST value of an S-NSSAI in the S-NSSAI(s) of the HPLMN to which the SST value is mapped. The coding of the SST value part is defined in 3GPP TS 23.003 [4].
mapped HPLMN Slice differentiator (SD) (octet 8 to octet 10)This field contains the 24 bit SD value of an S-NSSAI in the S-NSSAI(s) of the HPLMN to which the SD value is mapped. The coding of the SD value part is defined in 3GPP TS 23.003 [4].
NOTE 1: Octet 3 shall always be included.NOTE 2: If the octet 4 is included, then octet 5 and octet 6 shall be included.NOTE 3: If the octet 7 is included, then octets 8, 9, and 10 may be included.NOTE 4: If the octet 8 is included, then octet 9 and octet 10 shall be included.NOTE 5: If only HPLMN S-NSSAI or subscribed SNPN S-NSSAI is included, then octets 7 to 10 shall not be included.