| Network Working Group | V. Padebettu |
| Internet-Draft | Juniper Networks Inc. |
| Intended status: Informational | August 30, 2020 |
| Expires: March 3, 2021 |
5G Wireline Transport over PPP
draft-padebettu-5g-wireline-transport-over-ppp-00
To support connecting 5G residential gateways(5G-RG) to 5G Core (5GC) over wireline access, the control packets and data packets of the 5G-RG should be transported over the wireline access network (W-AN) to Access Gateway Function(W-AGF).
The Point-to-Point Protocol (PPP) [RFC1661] provides a standard method for transporting multi-protocol datagrams over point-to-point links. PPP defines an extensible Link Control Protocol, and proposes a family of Network Control Protocols for establishing and configuring different network-layer protocols.
This document defines the 5G Wireline Control Protocol(5WCP) for establishing and configuring the 5G Wireline Data protocol(5W Data) over PPP for Wireline Access for 5G Networks. The method inherits multiplexing of traffic for multiple 5G-RGs per VLAN from PPPoE [RFC2516] and defines multiplexing multiple PDU Sessions per 5G-RG.
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Wireless Wireline convergence with 5G ("fifth generation") mobile network introduces 5G Access Gateway Function (W-AGF is defined in [TS.23.316-3GPP]) as Wireline Access Network (W-AN). W-AGF transports the Control Packets from the 5G capable Residential Gateway(5G-RG) to the 5G Control Plane(5GCP) and transports the Data Packets from the 5G-RG to the 5G User Plane Function(UPF). 5G-RG is connected to the W-AGF over the wireline access based on TR-101 [BBF.TR.101].
The wireline transport defined for the 5G-RG is based on existing wireline technologies for faster implementation and adaptation. 5G defines end-to-end QoS which requires the wireline transport to carry the 5G QoS information inline with the data.
5G NAS [TS.24.501-3GPP] is the control channel which registers, authenticates and authorizes the end-point, providing the information (IP Address, Gateway, DNS, etc. )for transporting the data from the 5G-RG over the link.
PPP has three main components:
In order to establish communications over a point-to-point link, each end of the PPP link must first send LCP packets to configure and test the data link. After the link has been established from negotiating optional facilities as needed by the LCP, PPP must send 5G NAS control packets to choose and configure the 5G NAS network-layer protocol. Once 5G NAS has reached the Opened state, 5G datagrams can be sent over the link.
The link will remain configured for communications until explicit LCP or 5G NAS packets close the link down, or until some external event occurs (an inactivity timer expires or network administrator intervention).
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.
This document uses the following acronyms:
3GPP 3rd Generation Partnership Project 5GC 5th Generation Core (network) 5GCP 5G Control Plane W-AGF Wireline Access Gateway Function NAS Non-Access Stratum PDU Protocol Data Unit QFI QoS Flow Identifier QoS Quality of Service RG Residential Gateway 5G-RG 5G capable Residential Gateway RQI Reflective QoS Indicator WWC Wireless Wireline Convergence
The 5G Wireline Control Protocol (5WCP) is responsible for configuring, enabling, and disabling the 5G Wireline protocol modules on both ends of the point-to-point link. 5WCP uses the same packet exchange mechanism as the Link Control Protocol (LCP) [RFC1661]. 5WCP packets may not be exchanged until PPP has reached the Network-Layer Protocol phase. 5WCP packets received before this phase is reached MUST be silently discarded.
5WCP is exactly same as the LCP [RFC1661] with the following exceptions:
The format of 5WCP packets is defined here.
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | CODE | IDENTIFIER | LENGTH | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | DATA ~ +-+-+-+-++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: 5G Wireline Control Protocol Packet Format.
The description of each field is as follows:
The format of 5WCP Payload is defined here.
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | VER | FLAGS | MSG TYPE | ATLV COUNT | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ATTRIBUTE TLV(s) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PAYLOAD (NAS PDU) ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: 5G Wireline Control Payload Format.
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TYPE | LENGTH | VALUE ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Attribute TLV Format.
The description of each field is as follows:
Before any 5G Wireline Data packets may be communicated, PPP must reach the Network-Layer Protocol phase, and the 5G Wireline Control Protocol must reach the Opened state.
Exactly one 5G Wireline Data packet is encapsulated in the PPP Data Link Layer frames where the Protocol field indicates type hex 00## / 0037 (5G Wireline Data).
The maximum length of an IP packet transmitted over a PPP link is same as the maximum length of the Information field of a PPP data link layer frame.
The format of 5G Wireline Data is defined here.
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | VER |U|R| FLAGS | PROTOCOL ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PDU SESSION ID| QFI | LENGTH | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PAYLOAD ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
Figure 4: 5G Wireline Data Packet Format.
The description of each field is as follows:
The following sections describe the detailed 5WCP procedures that map to 5G NAS Procedures as described in [TS.24.501-3GPP]
The 5WCP Registration Procedure is described below:
5G-RG W-AGF
+----------------------------------------------------------+
+----Configure-Request (Registration Request)---->
<----Configure-Ack (Registration Accept)---------+
<----Configure-Nack (Registration Reject)--------+
+----Configure-Ack(Registration Complete)--------->
The 5WCP De-registration Procedure is described below:
5G-RG W-AGF
+---------------------------------------------------------+
<--Terminate-Request (De-registration Request)--+
+---Terminate-Ack (De-registration Accept)------>
5G-RG W-AGF
+---------------------------------------------------------+
+--Terminate-Request (De-registration Request)-->
<------Terminate-Ack (De-registration Accept)---+
The 5WCP Authentication Procedure is described below:
5G-RG W-AGF
+----------------------------------------------------------+
<---Configure-Request (Authentication Request)---+
+-----Configure-Ack (Authentication Response)---->
<-----Configure-Ack (Authentication Result)------+
+-----Configure-Nack (Authentication Failure)---->
<-----Configure-Nack (Authentication Reject)-----+
The 5WCP Identity Procedure is described below:
5G-RG W-AGF
+--------------------------------------------------------+
<----Configure-Request (Identity Request)------+
+----Configure-Ack (Identity Response)--------->
The 5WCP Configuration Update Procedure is described below:
5G-RG W-AGF
+-----------------------------------------------------------+
<--Configure-Request (Configuration Update Command)--+
+--Configure-Ack (Configuration Update Complete)----->
The 5WCP Service Request Procedure is described below:
5G-RG W-AGF
+----------------------------------------------------------+
+------Configure-Request (Service Request)------>
<-------Configure-Ack (Service Accept)----------+
<------Configure-Nack (Service Reject)----------+
The 5WCP Notification Procedure is described below:
5G-RG W-AGF
+----------------------------------------------------------+
<-------Configure-Request (Notification)---------+
+----Configure-Ack (Notification Response)-------->
The 5WCP Security Mode Procedure is described below:
5G-RG W-AGF
+----------------------------------------------------------+
<---Configure-Request (Security Mode Command)---+
+---Configure-Ack (Security Mode Complete)------>
+---Configure-Nack (Security Mode Reject)------->
The 5WCP UL/DL Procedure is described below:
5G-RG W-AGF
+----------------------------------------------------------+
<-----Configure-Request (DL NAS Transport)-----+
+----------------Configure-Ack ---------------->
+-----Configure-Request (UL NAS Transport)----->
<----------------Configure-Ack ----------------+
The 5WCP 5GMM Status Procedure is described below:
5G-RG W-AGF
+----------------------------------------------------------+
<-------Configure-Request (5GMM Status)-------+
+----------------Configure-Ack ---------------->
+-------Configure-Request (5GMM Status)-------->
<----------------Configure-Ack ----------------+
The 5WCP PDU Session Establishment Procedure is described below:
5G-RG W-AGF
+------------------------------------------------------------+
+-Configure-Request(PDU Session Establishment Request)->
<---Configure-Ack(PDU Session Establishment Accept)----+
<---Configure-Nack(PDU Session Establishment Reject)---+
The 5WCP PDU Session Modification Procedure is described below:
5G-RG W-AGF
+------------------------------------------------------------+
+-Configure-Request(PDU Session Modification Request)->
<---Configure-Nack(PDU Session Modification Reject)---+
<-Configure-Request(PDU Session Modification Command)-+
+---Configure-Ack(PDU Session Modification Complete)-->
+-Configure-Nack(PDU Session Modification Cmd Reject)->
The 5WCP PDU Session Release Procedure is described below:
5G-RG W-AGF
+------------------------------------------------------------+
+---Configure-Request(PDU Session Release Request)--->
<-----Configure-Nack(PDU Session Release Reject)-----+
<---Configure-Request(PDU Session Release Command)---+
+-----Configure-Ack(PDU Session Release Complete)---->
The 5WCP 5GSM Status Procedure is described below:
5G-RG W-AGF
+----------------------------------------------------------+
<-------Configure-Request (5GSM Status)-------+
+----------------Configure-Ack ---------------->
+-------Configure-Request (5GSM Status)-------->
<----------------Configure-Ack ----------------+
5G NAS procedures used for session life cycle maintenance employ ciphering and integrity protection as defined in [TS.33.501-3GPP].
There is no impact on the security of a fixed access network and it will be equivalent to current practice.
IANA is requested to create a registry on the Point-to-Point (PPP) Protocol Field Assignments IANA Web page as follows:
Registry Name: PPP DLL Protocol Numbers
Registration Procedure:
0xxx-3xxx IETF Review Network Layer Protocols
8xxx-bxxx IETF Review Network Control Protocols
Code-Points
----------------------------------------------------------
Value (in hex) Protocol Name Reference
----------------------------------------------------------
0037 5G Wireline Data [This Document]
8037 5G Wireline Control [This Document]
-----------------------------------------------------------
Some of the text in this document is taken from previous documents produced by the Point-to-Point Protocol Working Group of the Internet Engineering Task Force (IETF).
The author would also like to thank Ron Bonica for all his help and John Gibbons for reviewing the document.
| [RFC2119] | Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997. |
| [RFC8174] | Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017. |
| [RFC1661] | Simpson, W., "The Point-to-Point Protocol (PPP)", STD 51, RFC 1661, DOI 10.17487/RFC1661, July 1994. |
| [TS.24.501-3GPP] | 3rd Generation Partnership Project (3GPP), "Non-Access-Stratum (NAS) protocol for 5G System (5GS); Stage 3, 3GPP TS 24.501 v16.5.1", July 2020. |
| [TS.24.007-3GPP] | 3rd Generation Partnership Project (3GPP), "Wireless and wireline convergence access support for the 5G System (5GS) v16.3.0", July 2020. |