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Checking references for intended status: Informational ---------------------------------------------------------------------------- No issues found here. Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 Internet Draft Dave Allan, Ericsson ed. 2 Intended status: Informational Donald Eastlake, Futurewei 3 Expires: April 2021 David Woolley, Telstra 4 October 2020 6 5G Wireless Wireline Convergence User Plane Encapsulation (5WE) 7 draft-allan-5g-fmc-encapsulation-07 9 Abstract 11 As part of providing wireline access to the 5G Core (5GC), deployed 12 wireline networks carry user data between 5G residential gateways 13 and the 5G Access Gateway Function (AGF). The encapsulation method 14 specified in this document supports the multiplexing of traffic for 15 multiple PDU sessions within a VLAN delineated access circuit, 16 permits legacy equipment in the data path to inspect certain packet 17 fields, carries 5G QoS information associated with the packet data, 18 and provides efficient encoding. It achieves this by specific points 19 of similarity with the RFC 2516 PPPoE data packet encapsulation. 21 Status of this Memo 23 This Internet-Draft is submitted to IETF in full conformance 24 with the provisions of BCP 78 and BCP 79. 26 Internet-Drafts are working documents of the Internet 27 Engineering Task Force (IETF), its areas, and its working 28 groups. Note that other groups may also distribute working 29 documents as Internet-Drafts. 31 Internet-Drafts are draft documents valid for a maximum of six 32 months and may be updated, replaced, or obsoleted by other 33 documents at any time. It is inappropriate to use Internet- 34 Drafts as reference material or to cite them other than as 35 "work in progress". 37 The list of current Internet-Drafts can be accessed at 38 http://www.ietf.org/ietf/1id-abstracts.txt. 40 The list of Internet-Draft Shadow Directories can be accessed 41 at http://www.ietf.org/shadow.html. 43 This Internet-Draft will expire on April 2021. 45 Copyright and License Notice 47 Copyright (c) 2020 IETF Trust and the persons identified as the 48 document authors. All rights reserved. 50 This document is subject to BCP 78 and the IETF Trust's Legal 51 Provisions Relating to IETF Documents 52 (http://trustee.ietf.org/license-info) in effect on the date of 53 publication of this document. Please review these documents 54 carefully, as they describe your rights and restrictions with 55 respect to this document. Code Components extracted from this 56 document must include Simplified BSD License text as described 57 in Section 4.e of the Trust Legal Provisions and are provided 58 without warranty as described in the Simplified BSD License. 60 Table of Contents 62 1. Introduction...................................................2 63 1.1. Requirements Language........................................4 64 1.2. Acronyms.....................................................4 65 2. Data Encapsulation Format......................................4 66 3. Acknowledgements...............................................6 67 4. Security Considerations........................................6 68 5. IANA Considerations............................................6 69 6. References.....................................................7 70 6.1. Normative References.........................................7 71 6.2. Informative References.......................................7 72 7. Authors' Addresses.............................................8 74 1. Introduction 76 Converged 5G ("fifth generation") wireline networks carry user data 77 between 5G residential gateways (5G-RG) and the 5G Access Gateway 78 Function (identified as a Wireline-AGF (W-AGF) by 3GPP in [TS23316]) 79 across deployed access networks based on Broadband Forum [TR101] and 80 [TR178]. 82 The transport encapsulation used needs to meet a variety of 83 requirements including the following: 85 - The ability to multiplex multiple logical connections (Protocol 86 Data Unit (PDU) Sessions as defined by 3GPP) within a VLAN 87 identified point to point logical circuit between a 5G-RG and a W- 88 AGF. 90 - To allow unmodified legacy equipment in the data path to identify 91 the encapsulation and inspect specific fields in the payload. 92 Some access nodes in the data path between the 5G-RG and the W- 93 AGF (Such as digital subscriber loop access multiplexers (DSLAMs) 94 and optical line terminations (OLTs)) currently inspect packets 95 identified by specific Ethertypes to identify protocols such as 96 the point to point protocol over ethernet (PPPoE), IP, ARP, and 97 IGMP. This may be for the purpose of enhanced QoS, policing of 98 identifiers and other applications. Some deployments are 99 dependent upon this inspection. Such devices are able to do this 100 for PPPoE or IP over ethernet (IPoE) packet encodings but would 101 be unable to do so if a completely new encapsulation, or an 102 existing encapsulation using a new Ethertype, were used. 104 - To carry per packet 5G QoS information. 106 - Fixed access residential gateways are sensitive to the complexity 107 of packet processing, therefore an encapsulation that minimizes 108 processing is an important consideration. 110 A data encapsulation that uses a common Ethertype and has certain 111 fields appearing at the same offset as the [RFC2516] PPPoE data 112 encapsulation can address these requirements. This data 113 encapsulation is referred to as the 5G WWC user plane Encapsulation 114 or 5WE. Currently deployed access nodes do not police the VER, TYPE 115 and CODE fields of an RFC 2516 header, and only perform limited 116 policing of stateful functions with respect to the procedures 117 documented in RFC 2516. Therefore, these fields have a different 118 definition for 5WE and are used to: 120 - Identify that the mode of operation for packets encapsulated in 121 such a fashion uses non-access stratum (NAS, a logical control 122 interface between user equipment (UE) and 5GC as specified by 123 3GPP) based 5G WWC session establishment and life cycle 124 maintenance procedures as documented in [TS23502][TS23316] instead 125 of legacy PPP/PPPoE session establishment procedures (i.e. PADI 126 discipline, LCP, NCP etc.). In this scenario "discovery" is 127 performed by means outside the scope of this document. 129 - Permit the session ID field to be used to identify the 5G PDU 130 session the encapsulated packet is part of. 132 - Communicate per-packet 5G QoS Flow Identifier (QFI) and 133 Reflective QoS Indication (RQI) information from the 5GC to the 134 5G-RG. 136 This 5G specific redesign of fields not inspected by deployed 137 equipment results in an encapsulation uniquely applicable to the 138 requirements for the communication of PDU session traffic between 139 the subscriber premises and the 5G system over wireline networks. 140 The 6 byte RFC 2516 data packet header followed by a 2 byte PPP 141 protocol ID is also the most frugal of the encapsulations that are 142 currently supported by legacy access equipment that could be adapted 143 to meet these requirements. 145 This encapsulation is expected to be used in environments where RFC 146 2516 is deployed. Therefore implementations are required to examine 147 the version number and react accordingly. 149 This encapsulation may have MTU issues when used for Ethernet 150 multiplexing in networks where the underlying Ethernet payload is 151 limited to 1500 bytes. 153 This encapsulation is not suitable for other network environments, 154 e.g., general use over the public Internet. 156 1.1. Requirements Language 158 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL 159 NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", 160 "MAY", and "OPTIONAL" in this document are to be interpreted as 161 described in BCP 14 [RFC2119] [RFC8174] when, and only when, they 162 appear in all capitals, as shown here. 164 1.2. Acronyms 166 This document uses the following acronyms: 168 3GPP 3rd Generation Partnership Project 169 5WE 5G WWC Encapsulation 170 5GC 5th Generation Core (network) 171 DSLAM Digital Subscriber Loop Access Multiplexer 172 W-AGF Wireline Access Gateway Function 173 IPoE IP over Ethernet 174 NAS Non-Access Stratum 175 OLT Optical Line Termination 176 PDU Protocol Data Unit 177 PPPoE PPP over Ethernet 178 QFI QoS Flow Identifier 179 QoS Quality of Service 180 RG Residential Gateway 181 RQI Reflective QoS Indicator 182 WWC Wireless Wireline Convergence 184 2. Data Encapsulation Format 186 The Ethernet payload [IEEE802] for PPPoE [RFC2516] is indicated by 187 an Ethertype of 0x8864. The information following that Ethertype 188 uses a value of 2 in the VER field for the repurposing of the PPPoE 189 data encapsulation as the 5G WWC user plane encapsulation (5WE). The 190 5G WWC User Plane encapsulation is structured as follows: 192 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 1 193 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 194 | VER | TYPE | QFI |R|0| SESSION_ID | 195 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 196 | LENGTH | PROTOCOL ID | 197 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 198 | DATA PAYLOAD ~ 199 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 201 The description of each field is as follows: 203 VER is the version. It MUST be set to 0x02. 205 TYPE is the message type. It MUST be set to 0x01. 207 QFI encodes the 3GPP 5G QoS Flow Identifier [TS38415] to be used 208 for mapping 5G QoS to IP DSCP/802.1 P-bits [IEEE802]. 210 R (short for Reflective QoS Indication [TS38415]) encodes the one 211 bit RQI. It is set by the network side 5WE termination for 212 downstream traffic and ignored by the network for upstream 213 traffic. 215 0 indicates the bit(s) MUST be sent as zero and ignored on 216 receipt. 218 SESSION_ID is a 16-bit unsigned integer in network byte order. It 219 is used to distinguish different PDU sessions that are in the 220 VLAN delineated multiplex. A value of 0xffff is reserved for 221 future use and MUST NOT be used. 223 LENGTH is the length in bytes of the data payload including 224 the initial Protocol ID. It is 16 bits in network byte order. 226 PROTOCOL ID is the 16 bit identifier of the data payload type 227 encoded using values from the IANA PPP DLL protocol numbers 228 registry. (https://www.iana.org/assignments/ppp-numbers/ppp- 229 numbers.xhtml#ppp-numbers-2) 231 The following values are valid in this field for 5G 232 WWC use: 234 0x0021: IPv4 236 0x0031: Ethernet (referred to in PPP as "bridging") 237 0x0057: IPv6 239 Packets received that do not contain one of the above 240 protocol IDs are silently discarded. 242 DATA PAYLOAD is encoded as per the protocol ID. 244 3. Acknowledgements 246 This memo is a result of comprehensive discussions by the Broadband 247 Forum's Wireline Wireless Convergence Work Area. 248 The authors would also like to thank Joel Halpern and Dirk Von Hugo 249 for their detailed review of this draft. 251 4. Security Considerations 253 5G NAS procedures used for session life cycle maintenance employ 254 ciphering and integrity protection [TS23502]. They can be considered 255 to be a more secure session establishment discipline than existing 256 RFC 2516 procedures, at least against on path attackers. 257 The design of the 5WE encapsulation will not circumvent existing 258 anti-spoofing and other security procedures in deployed equipment. 259 The existing access equipment will be able to identify fields that 260 they normally process and policed as per existing RFC 2516 traffic. 262 Therefore, the security of a fixed access network using 5WE will be 263 equivalent or superior to current practice. 265 5WE encapsulated traffic is used on what the 5GC considers to be 266 trusted non-3GPP interfaces, therefore is not ciphered. 5WE is not 267 suitable for use over an untrusted non-3GPP interface. 269 5. IANA Considerations 271 IANA is requested to create a registry on the Point-to-Point (PPP) 272 Protocol Field Assignments IANA Web page as follows: 274 Registry Name: PPP Over Ethernet Versions 275 Registration Procedure: Specification Required 276 References: [RFC2516] [this document] 278 VER Description Reference 279 ----- ----------------------------- ----------- 280 0 reserved [this document] 281 1 PPPoE [RFC2516] 282 2 5G WWC User Plane Encapsulation [this document] 284 3-15 unassigned [this document] 286 IANA is requested to add [this document] as an additional reference 287 for Ethertype 0x8864 in the Ethertypes table on the IANA "IEEE 802 288 Numbers" web page.(https://www.iana.org/assignments/ieee-802- 289 numbers/ieee-802-numbers.xhtml#ieee-802-numbers-1) 291 6. References 293 6.1. Normative References 294 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 295 Requirement Levels", BCP 14, RFC 2119, March 1997. 296 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 297 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 298 May 2017, . 299 [RFC2516] "A Method for Transmitting PPP Over Ethernet (PPPoE)", 300 IETF RFC 2516, February 1999 301 [TS38415] 3rd Generation Partnership Project; Technical 302 Specification Group Radio Access Network; NG-RAN; PDU 303 Session User Plane Protocol (Release 15), 3GPP TS38.415 304 [TS23502] 3rd Generation Partnership Project; Technical 305 Specification Group Services and System Aspects; 306 Procedures for the 5G System (Release 16), 3GPP TS23.502 307 [TS23316] 3rd Generation Partnership Project; Technical 308 Specification Group Services and System Aspects; 309 Wireless and wireline convergence access support 310 for the 5G System (5GS) (Release 16), 3GPP TR23.316, 311 November 2018 313 6.2. Informative References 314 [TR101] "Migration to Ethernet Based Broadband Aggregation", 315 Broadband Forum Technical Report: TR-101 issue 2, July 316 2011 317 [TR178] "Multi-service Broadband Network Architecture and Nodal 318 Requirements", Broadband Forum Technical Report: TR-178, 319 September 2014 320 [IEEE802] 802, IEEE, "IEEE Standard for Local and Metropolitan 321 Networks: Overview and Architecture", IEEE Std 802-2014. 323 7. Authors' Addresses 324 Dave Allan (editor) 325 Ericsson 326 2455 Augustine Drive 327 San Jose, CA 95054 USA 328 Email: david.i.allan@ericsson.com 330 Donald E. Eastlake 3rd 331 Futurewei Technologies 332 2386 Panoramic Circle 333 Apopka, FL 32703 USA 334 Phone: +1-508-333-2270 335 Email: d3e3e3@gmail.com 337 David Woolley 338 Telstra Corporation 339 242 Exhibition St 340 Melbourne, 3000 341 Australia 342 Email: david.woolley@team.telstra.com