• The ability to multiplex multiple logical connections (Protocol Data Unit (PDU) sessions as defined by 3GPP) within a VLAN-identified point-to-point logical circuit between a 5G-RG and a W-AGF.
• To allow unmodified legacy equipment in the data path to identify the encapsulation and inspect specific fields in the payload. Some access nodes in the data path between the 5G-RG and the W-AGF (such as digital subscriber loop access multiplexers (DSLAMs) and optical line terminations (OLTs)) currently inspect packets identified by specific Ethertypes to identify protocols such as the Point-to-Point Protocol over Ethernet (PPPoE), IP, ARP, and IGMP. This may be for the purpose of enhanced QoS, the policing of identifiers, and other applications. Some deployments are dependent upon this inspection. Such devices are able to do this for PPPoE or IP-over-Ethernet (IPoE) packet encodings but would be unable to do so if a completely new encapsulation, or an existing encapsulation using a new Ethertype, were used.
• To carry per-packet 5G QoS information.
• An encapsulation that minimizes processing since fixed access residential gateways are sensitive to the complexity of packet processing. While not a strict requirement, this is an important consideration.

• Identify that the mode of operation for packets encapsulated in such a fashion uses 5G WWC session establishment based on non-access stratum (NAS, a logical control interface between user equipment (UE) and a 5th Generation Core Network (5GC) as specified by 3GPP) and life-cycle maintenance procedures as documented in [TS23502] and [TS23316] instead of legacy PPP/PPPoE session establishment procedures [RFC 2516] (i.e., PADI discipline, LCP, NCP, etc.). In this scenario, "discovery" is performed by means outside the scope of this document.
• Permit the session ID field to be used to identify the 5G PDU session the encapsulated packet is part of.
• Communicate per-packet 5G QoS Flow Identifier (QFI) and Reflective QoS Indication (RQI) information from the 5GC to the 5G-RG.

• If the version number is 1 and PPPoE [RFC 2516] is supported, process the frame further; else, silently discard it.
• If the version number is 2 and 5WE is supported, process the frame further; else, silently discard it.

3GPP

3rd Generation Partnership Project

5WE

5G Wireless Wireline Convergence User Plane Encapsulation

5GC

5th Generation Core (network)

DSLAM

Digital Subscriber Loop Access Multiplexer

W-AGF

Wireline Access Gateway Function

IPoE

IP over Ethernet

NAS

Non-Access Stratum

OLT

Optical Line Termination

PDU

Protocol Data Unit

PPPoE

PPP over Ethernet

QFI

QoS Flow Identifier

QoS

Quality of Service

RG

Residential Gateway

RQI

Reflective QoS Indicator

WWC

Wireless Wireline Convergence

   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  |  TYPE |     QFI   |R|0|           SESSION_ID          |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |            LENGTH             |          PROTOCOL ID          |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                         DATA PAYLOAD         ~
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

VER:

The version. It MUST be set to 0x02.

TYPE:

The message type. It MUST be set to 0x01.

QFI:

Encodes the 3GPP 5G QoS Flow Identifier [TS38415] to be used for mapping 5G QoS to IP DSCP/802.1 P-bits [IEEE802].

R:

(Short for Reflective QoS Indication [TS38415]) Encodes the one-bit RQI. It is set by the network-side 5WEtermination for downstream traffic and ignored by the network for upstreamtraffic.

0:

Indicates the bit(s) that MUST be sent as zero and ignored onreceipt.

SESSION_ID:

A 16-bit unsigned integer in network byte order. It is used to distinguishdifferent PDU sessions that are in the VLAN-delineated multiplex. A value of0xffff is reserved for future use and MUST NOT be used.

LENGTH:

The length in bytes of the data payload, including the initial ProtocolID. It is 16 bits in network byte order.

PROTOCOL ID:

The 16-bit identifier of the data payload type encoded using values from the IANA "PPP DLL Protocol Numbers" registry <https://www.iana.org/assignments/ppp-numbers>.

The following values are valid in this field for 5G WWC use:

• 0x0021: IPv4
• 0x0031: Bridging PDU (Ethernet)
• 0x0057: IPv6

Packets received that do not contain one of the above protocol IDs are silently discarded.

DATA PAYLOAD:

Encoded as per the protocol ID.

Registry Name:

PPP Over Ethernet Versions

Registration Procedure:

Specification Required

References:

[RFC 2516] [RFC8822]

[RFC2119]

S. Bradner, "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.

[RFC2516]

L. Mamakos, K. Lidl, J. Evarts, D. Carrel, D. Simone, and R. Wheeler, "A Method for Transmitting PPP Over Ethernet (PPPoE)", RFC 2516, DOI 10.17487/RFC2516, February 1999,
<https://www.rfc-editor.org/info/rfc2516>.

[RFC8174]

B. Leiba, "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017,
<https://www.rfc-editor.org/info/rfc8174>.

[TS23316]

3GPP, "Wireless and wireline convergence access support for the 5G System (5GS)", TS 23.316, December 2018.

[TS23502]

3GPP, "Procedures for the 5G System (5GS)", TS 23.502, December 2016.

[TS38415]

3GPP, "NG-RAN; PDU session user plane protocol", TS 38.415, March 2018.

[IEEE802]

IEEE, "IEEE Standard for Local and Metropolitan Networks: Overview and Architecture", Std 802-2014, DOI 10.1109/IEEESTD.2014.6847097, June 2014,
<https://doi.org/10.1109/IEEESTD.2014.6847097>.

[TR101]

Broadband Forum, "Migration to Ethernet Based Broadband Aggregation", July 2011.

[TR178]

Broadband Forum, "Multi-service Broadband Network Architecture and Nodal Requirements", September 2014.

[TS33501]

3GPP, "Security architecture and procedures for 5G System", TS 33.501, December 2019.

Dave Allan

Donald E. Eastlake 3rd

David Woolley