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TECHNICAL SPECIFICATION
Universal Mobile Telecommunications System (UMTS);
LTE;
Domain Name System Procedures;
Stage 3
(3GPP TS 29.303 version 15.4.0 Release 15)
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3GPP TS 29.303 version 15.4.0 Release 15 1 ETSI TS 129 303 V15.4.0 (2019-04)
Reference
RTS/TSGC-0429303vf40
Keywords
LTE,UMTS
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3GPP TS 29.303 version 15.4.0 Release 15 2 ETSI TS 129 303 V15.4.0 (2019-04)
Intellectual Property Rights
Essential patents
IPRs essential or potentially essential to normative deliverables may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
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Foreword
This Technical Specification (TS) has been produced by ETSI 3rd Generation Partnership Project (3GPP).
The present document may refer to technical specifications or reports using their 3GPP identities, UMTS identities or
GSM identities. These should be interpreted as being references to the corresponding ETSI deliverables.
The cross reference between GSM, UMTS, 3GPP and ETSI identities can be found under
.
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of
provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
ETSI
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3GPP TS 29.303 version 15.4.0 Release 15 3 ETSI TS 129 303 V15.4.0 (2019-04)
Contents
Intellectual Property Rights . 2
Foreword . 2
Modal verbs terminology . 2
Foreword . 6
1 Scope . 7
2 References . 7
3 Definitions, symbols and abbreviations . 8
3.1 Definitions . 8
3.2 Abbreviations . 8
4 General DNS Based Node Selection Description . 9
4.1 Resource Records . 9
4.1.1 A and AAAA . 9
4.1.2 NAPTR . 9
4.1.3 SRV . 10
4.2 Selecting Domain Names . 10
4.3 Identifying Nodes, Services and Protocols . 10
4.3.1 IETF RFC 3958 Service and Protocol service names for 3GPP . 10
4.3.2 Identification of canonical node names . 10
4.3.3 Services from node names or other FQDN identifying a service. 11
4.3.3.1 General . 11
4.3.3.2 Procedure . 12
4.3.3.2.1 S-NAPTR Procedure - General . 12
4.3.3.2.2 S-NAPTR Procedure for a canonical node name . 12
4.3.3.3 Services of a PGW from PGW node name (or collocated PGW/GGSN) . 12
4.3.3.4 Services of a MME from MME node name (or GUTI or 5G-GUTI) . 14
4.3.3.5 Services of an SGSN from a P-TMSI . 15
4.3.3.6 Services of an SGW from SGW canonical node name . 16
4.3.3.7 Services of an MSC Server from MSC Server canonical node name . 17
4.3.3.8 Services of an AMF from AMF instance name (or 5G-GUTI) . 17
4A SGW/PGW selection using GTP-C load control . 18
4A.1 General . 18
4A.2 Node-level load control . 18
4A.3 APN-level load control . 19
5 Procedures for EPC Node Discovery and Selection . 20
5.1 Procedures for Discovering and Selecting a PGW . 20
5.1.1 Discovering a PGW for a 3GPP Access . 20
5.1.1.1 General . 20
5.1.1.2 Discovering a PGW or collocated PGW/GGSN for a 3GPP Access - S8/Gp roaming case
existing PDN . 21
5.1.1.3 Discovering a PGW or collocated PGW/GGSN for a 3GPP Access - S5/Gn intra-operator
existing PDN . 22
5.1.1.4 Discovering a PGW, collocated PGW/GGSN or GGSN for a 3GPP Access - S5/Gn intra-
operator initial attach. 23
5.1.2 Discovering a PGW for a non-3GPP Access with Network Based Mobility Management . 23
5.1.2.1 Discovering a PGW for a non-3GPP Access – S2a/S2b initial attach for roaming and non-
roaming . 23
5.1.2.2 Discovering a PGW for a non-3GPP Access – S2a/S2b initial attach and chained PMIP-based
S8-S2a/S2b . 24
5.1.3 Discovering a PGW for a non-3GPP Access with DSMIPv6 . 24
5.1.3.1 Discovering a PGW for a non-3GPP Access – S2c initial attach . 24
5.2 Procedures for Discovering and Selecting a SGW . 25
5.2.1 General . 25
5.2.2 SGW Selection during TAU or RAU with SGW change - 3GPP roaming case . 25
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5.2.3 SGW Selection during TAU or RAU with SGW change - non-roaming case . 26
5.2.4 SGW Selection during non-3GPP handover to 3GPP access . 27
5.3 Procedures for Discovering and Selecting a PGW and SGW . 27
5.4 Procedures for Discovering and Selecting an MME . 29
5.4A Procedures for Discovering and Selecting an AMF . 30
5.5 Procedures for Discovering and Selecting an SGSN . 31
5.5.1 General . 31
5.5.2 SGSN initial target selection based on RAI (UTRAN target/GERAN Iu mode target/GERAN Gb
mode target) . 31
5.5.3 SGSN initial target selection based on RNC-ID (UTRAN target/GERAN Iu mode target) . 33
5.5.4 Void . 34
5.6 GW Selection for SIPTO . 34
5.6.1 SIPTO above RAN . 34
5.6.2 SIPTO at the local network with LGW collocated with the (H)(e)NB . 34
5.6.3 SIPTO at the local network with stand-alone GW (LGW collocated with SGW) . 34
5.6.4 SIPTO for eHRPD . 35
5.7 Procedures for Discovering and Selecting an MSC Server . 35
5.7.1 General . 35
5.7.2 Selection of the MSC server enhanced for SRVCC based on target RAI (UTRAN / GERAN Iu &
A/Gb mode target) . 35
5.8 Procedures to support Dedicated Core Networks . 36
5.8.1 General . 36
5.8.2 SGW, PGW and GGSN Selection Procedure . 36
5.8.3 MMEGI and Null-NRI/SGSN Group ID Retrieval Procedure . 37
5.8.4 MME and SGSN Selection Procedure . 37
5.9 Procedures to support Cellular Internet of Things . 38
5.9.1 DCN based solution . 38
5.9.2 Alternative solution. 38
5.10 Procedures for Discovering and Selecting an SGW-U . 39
5.11 Procedures for Discovering and Selecting PGW-U . 39
5.12 Procedures to select a node supporting a particular network capability . 40
5.12.1 General principles . 40
5.12.1.1 General . 40
5.12.1.2 Selecting a node supporting a particular network capability within a Dedidated Core Network . 41
5.12.1.3 Selecting an SGW or PGW supporting a particular network capability . 41
5.12.2 Procedures to support Dual Connectivity with NR . 42
5.12.2.1 General . 42
5.12.3 Procedures to support interworking with 5GC. 42
5.12.3.1 General . 42
5.12.3.2 PGW-C/SMF selection. 42
5.12.3.3 PGW-U/UPF selection . 43
6 Procedures for OAM System Node Discovery . 43
6.1 Procedures for Relay Node OAM System Discovery . 43
6.1.1 General . 43
6.1.2 OAM System Selection based on Type Allocation Code . 43
7 Procedures for NF Discovery in 5G System . 43
7.1 General . 43
7.2 Procedure for AMF Discovery by 5G-AN . 43
Annex A (Informative): Examples . 45
A.1 Introduction . 45
A.2 Preconditions . 45
A.3 Collocated Simple LTE Example . 45
A.3.1 Network description . 45
A. 3.2 Master file for "Collocated Simple LTE Example" . 46
A. 3.3 SOA and NS records . 46
A. 3.4 MME file for "Collocated Simple LTE Example" . 47
A. 3.5 APN file for "Collocated Simple LTE Example" . 48
A. 3.6 PGW/SGW node file for "Collocated Simple LTE Example" . 49
A. 3.7 TAI/TAC file for "Collocated Simple LTE Example" . 51
A. 3.8 MME lookup based on GUTI for "Simple LTE Example" . 52
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3GPP TS 29.303 version 15.4.0 Release 15 5 ETSI TS 129 303 V15.4.0 (2019-04)
A. 3.9 APN lookup for "Simple LTE Example" (i.e. PGW candidate list) . 54
A. 3.10 TAI lookup for "Simple LTE Example" (i.e. SGW candidate list) . 56
A. 3.11 Finding the collocated SGW and PGW together . 58
A. 3.12 S11 lookup by SGW canonical node name . 59
A. 3.13 TAI lookup for "Colocation Simple LTE Example" (i.e. MME candidate list) . 60
A.4 LTE Example with Dedicated Core Network . 61
A.4.1 General . 61
A.4.2 APN file for DCN . 61
A.4.3 PGW/SGW node file for "Collocated Simple LTE Example" . 62
A.4.4 TAI/TAC file for DCN . 62
Annex B (Normative): DNS procedures clarifications . 64
B.1 DNS RFC procedures general clarifications . 64
B.2 DNS procedures 3GPP clarifications on S-NAPTR . 64
B.3 DNS procedures 3GPP clarifications for Dedicated Core Networks . 65
B.4 DNS procedures 3GPP clarifications for Network Capability . 65
Annex C (Informative): DNS Pseudo-Code . 66
C.1 S-NAPTR procedure base pseudo-code . 66
C.2 S-NAPTR procedure - no topon . 67
C.3 S-NAPTR procedure candidate list . 68
C.4 S-NAPTR procedure pseudo-code with topon . 69
Annex D (Informative): SGSN examples . 72
D.1 Introduction . 72
D.2 Preconditions . 72
D.3 SGSN file . 72
D.4 Null-NRI/SGSN Group ID file for DCN . 73
Annex E (Informative): SGW/PGW selection examples using GTP-C load control . 74
E.1 PGW selection using GTP-C load control at node level . 74
E.2 PGW selection using GTP-C load control at APN level . 74
E. 2.1 PGW selection when APN load control information is available for each candidate PGW . 74
E.2.2 PGW selection when APN load control information is not available for each candidate PGW . 75
Annex F (Informative): Examples for AMF Discovery by 5G AN . 76
F.1 Introduction . 76
F.2 Preconditions . 76
F.3 Example of an AMF Region with 2 AMF Sets . 76
F.3.1 Master file . 76
F.3.2 SOA and NS records . 76
F.3.3 AMF Set file . 76
Annex G (Informative): Change history . 77
History . 79
ETSI
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3GPP TS 29.303 version 15.4.0 Release 15 6 ETSI TS 129 303 V15.4.0 (2019-04)
Foreword
rd
This Technical Specification has been produced by the 3 Generation Partnership Project (3GPP).
The contents of the present document are subject to continuing work within the TSG and may change following formal
TSG approval. Should the TSG modify the contents of the present document, it will be re-released by the TSG with an
identifying change of release date and an increase in version number as follows:
Version x.y.z
where:
x the first digit:
1 presented to TSG for information;
2 presented to TSG for approval;
3 or greater indicates TSG approved document under change control.
y the second digit is incremented for all changes of substance, i.e. technical enhancements, corrections,
updates, etc.
z the third digit is incremented when editorial only changes have been incorporated in the document.
ETSI
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3GPP TS 29.303 version 15.4.0 Release 15 7 ETSI TS 129 303 V15.4.0 (2019-04)
1 Scope
The present document describes Domain Name System (DNS) Procedures for the Evolved Packet System. This
document covers the Evolved Packet Core gateway node selection using DNS (e.g. SGW and PGW nodes) excluding
all User Equipment (UE) initiated DNS-based discovery and selection procedures.
The present document specifies functions, procedures and information which apply to GERAN Iu mode. However,
functionality related to GERAN Iu mode is neither maintained nor enhanced.
The present document also describes the Domain Name System (DNS) Procedures for the Evolved Packet System
interworking with the 5G System, as specified in 3GPP TS 23.501 [28] and 3GPP TS 23.502 [29].
2 References
The following documents contain provisions which, through reference in this text, constitute provisions of the present
document.
- References are either specific (identified by date of publication, edition number, version number, etc.) or
non-specific.
- For a specific reference, subsequent revisions do not apply.
- For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including
a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same
Release as the present document.
[1] 3GPP TR 21.905: "Vocabulary for 3GPP Specifications".
[2] IETF R
...