5 NG Interface user plane protocol
38.4143GPPNG data transportNG-RANRelease 17TS
5.1 General
Both gNB and ng-eNB can be connected to the 5GC over the NG interface.
The transport layer for data streams over NG is an IP based Transport. The following figure shows the transport protocol stacks over NG.
Figure 5.1: Transport network layer for data streams over NG
The GTP-U (TS 29.281 [3]) protocol over UDP over IP shall be supported as the transport for data streams on the NG interface. The data link layer is as specified in clause 4.
The transport bearer is identified by the GTP-U TEID (TS 29.281 [3]) and the IP address (source TEID, destination TEID, source IP address, destination IP address).
5.2 GTP-U
The GTP-U (TS 29.281 [3]) protocol shall be used over the NG-U interface toward the 5GC.
5.3 UDP/IP
The path protocol used shall be UDP (IETF RFC 768 [4]).
The UDP port number for GTP-U shall be as defined in TS 29.281 [3].
The NG-RAN node and the 5GC shall support fragmentation and assembly of GTP packets at the IP layer.
The NG-RAN node and the 5GC shall support IPv6 (IETF RFC 8200 [5]) and/or IPv4 (IETF RFC 791 [6]).
There may be one or several IP addresses in the NG-RAN node and in the 5GC. The packet processing function in the 5GC shall send downstream packets of a given PDU Session to the NG-RAN node IP address (received in NGAP) associated to that particular PDU Session. The packet processing function in the NG-RAN node shall send upstream packets of a given PDU Session to the 5GC IP address (received in NGAP) associated to that particular PDU Session.
The Transport Layer Address signalled in NGAP messages is a bit string of
a) 32 bits in case of IPv4 address according to IETF RFC 791 [6]; or
b) 128 bits in case of IPv6 address according to IETF RFC 8200 [5]; or
c) 160 bits if both IPv4 and IPv6 addresses are signalled, in which case the IPv4 address is contained in the first 32 bits.
5.4 Diffserv code point marking
IP Differentiated Services code point marking (IETF RFC 2474 [7]) shall be supported. The mapping between traffic categories and Diffserv code points shall be configurable by O&M based on 5QI, the Priority Level (if explicitly signalled), and other NG-RAN traffic parameters (e.g. ARP). Traffic categories are implementation-specific and may be determined from the application parameters.
Annex A (informative):
Change history
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Change history |
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Date |
Meeting |
TDoc |
CR |
Rev |
Cat |
Subject/Comment |
New version |
|
May 2017 |
RAN3#96 |
R3-171514 |
Initial DraftTS endorsed |
0.0.2 |
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October 2017 |
RAN3#97bis |
R3-174240 |
Update some texts due to new 5G terminologies Add up "Diffserv code point marking" |
0.3.0 |
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January 2018 |
RAN3-adhoc1801 |
Incorporate agreed TPs from RAN3-adhoc1801 |
0.4.0 |
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May 2018 |
RAN3#100 |
R3-182642 |
Covering agreements of RAN3#100 |
0.5.0 |
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06-2018 |
RP-80 |
RP-180787 |
– |
– |
– |
Presentation to RAN for approval |
1.0.0 |
|
06-2018 |
RP-80 |
– |
– |
– |
Specification approved at TSG-RAN and placed under change control |
15.0.0 |
|
|
09-2018 |
RP-81 |
RP-181920 |
0001 |
– |
F |
Updated reference to IPv6 |
15.1.0 |
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2019-07 |
RP-84 |
RP-191396 |
0005 |
1 |
F |
Use of Priority Level and ARP for the DSCP Derivation at the gNB |
15.2.0 |
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2020-07 |
RP-88-e |
RP-201093 |
0006 |
1 |
D |
Rapporteur Clean-ups of TS38.414 |
15.3.0 |
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2020-07 |
SA-88-e |
– |
– |
– |
– |
Update to Rel-16 version (MCC) |
16.0.0 |
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2022-03 |
SA#95-e |
Promotion to Release 17 without technical change |
17.0.0 |
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