Content for TS 23.003 Word version: 18.3.0

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28.3.2.2.6 FQDN for SNPN N3IWF 28.3.2.2.6.1 Visited Country and Direct Access FQDN for SNPN N3IWF 28.3.2.2.6.2 Visited Country FQDN for SNPN N3IWF supporting Onboarding 28.3.2.2.6.3 Visited Country Emergency SNPN FQDN 28.3.2.2.6.4 Replacement field used in DNS-based Discovery of regulatory requirements for emergency services in SNPN 28.3.2.2.7 Replacement field used in DNS-based Discovery of SNPN N3IWF for regulatory requirements 28.3.2.2.7.1 General 28.3.2.2.7.2 Replacement field used in DNS-based Discovery of SNPN N3IWF supporting Onboarding 28.3.2.2.8 Prefixed Operator Identifier based N3IWF FQDN 28.3.2.2.9 Prefixed Tracking Area Identity based N3IWF FQDN
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28.3.2.2.6 FQDN for SNPN N3IWF |R16| p. 114

28.3.2.2.6.1 Visited Country and Direct Access FQDN for SNPN N3IWF p. 114

SNPN N3IWF is the N3IWF selected by the UE to access this SNPN service via PLMN, or directly via an untrusted non-3GPP access, as specified in clause 6.3.6.2a of TS 23.501.

The Visited Country FQDN for SNPN N3IWF used by a UE in the visited country to determine whether the visited country mandates the selection of an N3IWF in this country for the SNPN identified by the SNPN Identifier provided by the UE, shall be constructed as described below.

The Visited Country FQDN for SNPN N3IWF shall contain a MCC that uniquely identifies the country in which the UE is located, and the SNPN Identifier.

The Visited Country FQDN for SNPN N3IWF is composed of eight labels. The last three labels shall be "pub.3gppnetwork.org". The fifth label shall be "visited-country". The fourth label shall uniquely identify the MCC of the visited country. The third label shall be the SNPN Identifier as specified in clause 12.7. The first and second labels shall be "n3iwf.5gc". The Visited Country FQDN for SNPN N3IWF shall be constructed as follows:

"n3iwf.5gc.snpnid<SNPNID>.mcc<MCC>.visited-country.pub.3gppnetwork.org"

The <MCC> coding used in this FQDN shall be:

<MCC> = 3 digits

The <SNPNID> coding used in this FQDN shall be:

<SNPNID> = MCC || MNC || NID

As an example, the Visited Country FQDN for SNPN N3IWF for MCC 345, SNPN MCC 999, MNC 123, and NID 456789ABCDE is coded in the DNS as:

"n3iwf.5gc.snpnid999123456789ABCDE.mcc345.visited-country.pub.3gppnetwork.org".

28.3.2.2.6.2 Visited Country FQDN for SNPN N3IWF supporting Onboarding p. 115

SNPN N3IWF supporting Onboarding is specified in clause 5.30.2.12 of TS 23.501. If an SNPN for onboarding has been selected, Visited Country FQDN for SNPN N3IWF supporting Onboarding encoding is constructed by adding a label "onboarding" to Visited Country FQDN for SNPN N3IWF FQDN (see clause 28.3.2.2.6.1), indicating that the SNPN identified by the SNPN in the DNS response shall supports onboarding.

Visited Country FQDN for SNPN N3IWF supporting Onboarding shall be constructed as follows:

"onboarding.n3iwf.snpn-5gc.mcc<MCC>.visited-country.pub.3gppnetwork.org"

As an example, the Visited Country FQDN for SNPN N3IWF, which also supports Onboarding for MCC 345 is coded in the DNS as:

"onboarding.n3iwf.snpn-5gc.mcc345.visited-country.pub.3gppnetwork.org".

28.3.2.2.6.3 Visited Country Emergency SNPN FQDN p. 115

The Visited Country Emergency SNPN FQDN, used by a UE to determine whether the visited country mandates the selection of an SNPN N3IWF for emergency service in this country, shall be constructed as described below.

The Visited Country Emergency SNPN FQDN shall contain a MCC that uniquely identifies the country in which the UE is located.

The Visited Country Emergency SNPN FQDN is composed of eight labels. The last three labels shall be "pub.3gppnetwork.org". The fifth label shall be "visited-country". The forth label shall uniquely identify the MCC of the visited country. The second and third labels shall be "n3iwf.snpn-5gc". The first label shall be "sos". The resulting Visited Country Emergency SNPN FQDN shall be constructed as follows:

"sos.n3iwf.snpn-5gc.mcc<MCC>.visited-country.pub.3gppnetwork.org".

As an example, the Visited Country Emergency SNPN FQDN for MCC 345 is coded in the DNS as:

"sos.n3iwf.snpn-5gc.mcc345.visited-country.pub.3gppnetwork.org".

28.3.2.2.6.4 Replacement field used in DNS-based Discovery of regulatory requirements for emergency services in SNPN p. 115

If the visited country mandates the selection of an SNPN N3IWF for emergency services in this country, the NAPTR record(s) associated to the Visited Country Emergency SNPN FQDN shall be provisioned with the replacement field containing the identity of the SNPN(s) in the visited country which may be used for N3IWF selection.

The replacement field shall take the form of an SNPN Identifier based N3IWF FQDN as specified in clause 28.3.2.2.6.1 with the addition of the label "sos" before the labels "n3iwf.5gc".

As an example, the NAPTR records associated to the Visited Country Emergency SNPN FQDN for MCC 345, and for

SNPN MCC 999, MNC 012, and NID 345678ABCDE;
SNPN MCC 345, MNC 013, and NID 345678BCDEF; and
SNPN MCC 999, MNC 014, and NID 234567CDEFG,

are provisioned in the DNS as:

sos.n3iwf.5gc.snpn.mcc345.visited-country.pub.3gppnetwork.org

; IN NAPTR order
;              pref.
;                  flag
;                     service
;                        regexp
;                          replacement

  IN NAPTR 100 999 "" ""   sos.n3iwf.5gc.snpnid999012345678ABCDE.mcc345.pub.3gppnetwork.org
  IN NAPTR 100 999 "" ""   sos.n3iwf.5gc.snpnid345013345678BCDEF.mcc345.pub.3gppnetwork.org
  IN NAPTR 100 999 "" ""   sos.n3iwf.5gc.snpnid999014234567CDEFG.mcc345.pub.3gppnetwork.org

28.3.2.2.7 Replacement field used in DNS-based Discovery of SNPN N3IWF for regulatory requirements |R16| p. 116

28.3.2.2.7.1 General p. 116

If the visited country mandates the selection of an N3IWF in this country, the NAPTR record(s) associated to the Visited Country FQDN shall be provisioned with the replacement field containing FQDNs of SNPN N3IWFs located in the visited country.

28.3.2.2.7.2 Replacement field used in DNS-based Discovery of SNPN N3IWF supporting Onboarding p. 116

If the visited country mandates the selection of an SNPN N3IWF supporting onboarding in this country, the NAPTR record(s) associated to the Visited Country FQDN for SNPN N3IWF supporting Onboarding shall be provisioned with the replacement field containing Operator Identifier based Onboarding FQDN for SNPN N3IWF located in the visited country.

When UE sends the DNS query to the DNS server containing the Visited Country Onboarding FQDN for SNPN N3IWF (see clause 28.3.2.2.6.2), the DNS response should contain the Operator Identifier based Onboarding FQDN for SNPN N3IWF with the identity of an SNPN in the visited country supporting Untrusted non-3GPP access for UE Onboarding via N3IWF.

If the UE has selected an SNPN for onboarding, the UE sends DNS query to the DNS server containing the Operator Identifier based Onboarding FQDN for SNPN N3IWF to query the identifier of the N3IWF supporting Onboarding, the DNS response should contain the identifier of the N3IWF supporting the onboarding in the SNPN identified by the SNPN ID.

The replacement field shall take the form of Operator Identifier based Onboarding FQDN for SNPN N3IWF as below:

"onboarding.n3iwf.5gc.snpnid<SNPNID>.mcc<MCC>.pub.3gppnetwork.org"

As an example, the NAPTR records associated to the Visited Country Emergency SNPN FQDN for MCC 345, and for

SNPN MCC 999, MNC 123, and NID 456789ABCDE;
SNPN MCC 999, MNC 013, and NID 345678BCDEF,

are provisioned in the DNS as:

onboarding.n3iwf.snpn-5gc.mcc345.visited-country.pub.3gppnetwork.org

; IN NAPTR order
;              pref.
;                  flag
;                     service
;                        regexp
;                          replacement

  IN NAPTR 100 999 "" ""   onboarding.n3iwf.5gc.snpnid999123456789ABCDE.mcc345.pub.3gppnetwork.org
  IN NAPTR 100 999 "" ""   onboarding.n3iwf.5gc.snpnid999013345678BCDEF.mcc345.pub.3gppnetwork.org

28.3.2.2.8 Prefixed Operator Identifier based N3IWF FQDN |R18| p. 116

The Prefixed Operator Identifier based N3IWF FQDN, used by a UE that is configured with Slice-specific N3IWF prefix configuration, shall be constructed as specified for the Operator Identifier based N3IWF FQDN in clause 28.3.2.2.2, with the addition of <Prefix> before the labels "n3iwf.5gc". The <Prefix> is provided in the Slice-specific N3IWF prefix configuration for the selected PLMN that contains S-NSSAIs that match all (or most, in case there is no full match) of the S-NSSAIs that the UE is going to include in the Requested NSSAI in the subsequent Registration procedure, and is specified in TS 24.526.

The Prefixed Operator Identifier based N3IWF FQDN shall be constructed as follows:

"<Prefix>.n3iwf.5gc.mnc<MNC>.mcc<MCC>.pub.3gppnetwork.org"

As an example, the Prefixed Operator Identifier based N3IWF FQDN for MNC 123, MCC 345 with an example <Prefix> value "ssn3iwfprefix-Y" is coded in the DNS as:

"ssn3iwfprefix-Y.n3iwf.5gc.mnc123.mcc345.pub.3gppnetwork.org".

28.3.2.2.9 Prefixed Tracking Area Identity based N3IWF FQDN |R18| p. 117

The Prefixed Tracking Area Identity based N3IWF FQDN, used by a UE that is configured with Slice-specific N3IWF prefix configuration, shall be constructed as specified for the Tracking Area Identity based N3IWF FQDN in clause 28.3.2.2.3, with the addition of <Prefix> before the TAC. The <Prefix> is provided in the Slice-specific N3IWF prefix configuration for the selected PLMN that contains S-NSSAIs that match all (or most, in case there is no full match) of the S-NSSAIs that the UE is going to include in the Requested NSSAI in the subsequent Registration procedure, and is specified in TS 24.526.

There are two Prefixed Tracking Area Identity based N3IWF FQDNs defined: one based on a TAI with a 2 octet TAC and a 5GS one based on a 3 octet TAC.

The Prefixed Tracking Area Identity based N3IWF FQDN using a 2 octet TAC shall be constructed respectively as:

"<Prefix>.tac-lb<TAC-low-byte>.tac-hb<TAC-high-byte>.tac.n3iwf.5gc.mnc<MNC>.mcc<MCC>.pub.3gppnetwork.org"

The syntax and semantics of <TAC-high-byte>, <TAC-low-byte>, <MNC>, and <MCC> are specified in clause 28.3.2.2.3.
As an example, the Prefixed Tracking Area Identity based N3IWF FQDN for the TAC H'0B21, MCC 345, MNC 12, and an example <Prefix> value "ssn3iwfprefix-Y" is coded in the DNS as:

"ssn3iwfprefix-Y.tac-lb21.tac-hb0b.tac.n3iwf.5gc.mnc012.mcc345.pub.3gppnetwork.org"
The 5GS Prefixed Tracking Area Identity based N3IWF FQDN using a 3 octet TAC shall be constructed respectively as:

"<Prefix>.tac-lb<TAC-low-byte>.tac-mb<TAC-middle-byte>.tac-hb<TAC-high-byte>.5gstac.n3iwf.5gc.mnc<MNC>.mcc<MCC>.pub.3gppnetwork.org"

The syntax and semantics of <TAC-high-byte>, <TAC-middle-byte>, <TAC-low-byte>, <MNC>, and <MCC> are specified in clause 28.3.2.2.3.
As an example, the 5GS Prefixed Tracking Area Identity based N3IWF FQDN for the 5GS TAC H'0B1A21, MCC 345, MNC 12, and an example <Prefix> value "ssn3iwfprefix-Y" is coded in the DNS as:

"ssn3iwfprefix-Y.tac-lb21.tac-mb1a.tac-hb0b.5gstac.n3iwf.5gc.mnc012.mcc345.pub.3gppnetwork.org"