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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: July 2021 David Woolley, Telstra 4 January 2020 6 5G Fixed Mobile Convergence User Plane Encapsulation 7 draft-allan-5g-fmc-encapsulation-01 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 used 14 needs to meet a variety of requirements including being able to 15 multiplex the traffic of multiple PDU sessions within a VLAN 16 delineated access circuit, to permit legacy equipment in the data 17 path to snoop certain packet fields, to carry 5G QoS information 18 associated with the data, and to be efficiently encoded. This memo 19 specifies an encapsulation that meets these requirements. 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 July 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........................................3 64 1.2. Acronyms.....................................................3 65 2. Data Encapsulation Format......................................4 66 3. Acknowledgements...............................................5 67 4. Security Considerations........................................5 68 5. IANA Considerations............................................5 69 6. References.....................................................5 70 6.1. Normative References.........................................6 71 6.2. Informative References.......................................6 72 7. Authors' Addresses.............................................7 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 an Fixed-AGF (FAGF) by 3GPP in [5]) across 79 deployed TR-101[6] and TR-178[7] access networks. 81 The transport encapsulation used needs to meet a variety of 82 requirements including the following: 84 - The ability to multiplex multiple logical connections (Protocol 85 Data Unit (PDU) Sessions as defined by 3GPP) within a VLAN 86 identified p2p logical circuit between a 5G-RG and an F-AGF. 88 - To allow unmodified legacy equipment in the datapath to identify 89 the encapsulation and snoop specific fields in the payload. Some 90 access nodes in the data path between the 5G-RG and the F-AGF 91 (Such as DSLAMs and OLTs) currently snoop into packets identified 92 by specific ethertypes to identify protocols such as PPPoE, IP, 93 ARP and IGMP. This may be for the purpose of enhanced QoS, 94 policing of identifiers and other applications. Some deployments 95 are depended upon this snooping. Such devices are currently able 96 to do so for PPPoE or IPoE packet encodings but would be unable 97 to do so if a new encapsulation, or an existing encapsulation 98 using a new ethertype, were used. 100 - To carry per packet 5G QoS information. 102 - Fixed access is very sensitive to the complexity of residential 103 gateways, therefore encapsulation overhead and efficiency is an 104 important consideration. 106 A modified RFC 2516[3] PPPoE data encapsulation can address these 107 requirements. Currently deployed access nodes do not police the VER, 108 TYPE and CODE fields of an RFC 2516 header, and only perform limited 109 policing of stateful functions with respect to the procedures 110 documented in RFC 2516. Therefore these fields may be repurposed to: 112 - Identify that the mode of operation for packets encapsulated in 113 such a fashion uses non-access stratum(NAS, a logical control 114 interface between UE and 5GC as specified by 3GPP) based 5G FMC 115 session establishment and life cycle maintenance procedures as 116 documented in [4][5] instead of legacy PPP/PPPoE session 117 establishment procedures (i.e. PADI discipline, LCP, NCP etc.). 119 - Permit the session ID field to be used to identify the 5G PDU 120 session the encapsulated packet is part of. 122 - Communicate per-packet 5G QoS Flow Identifier (QFI) and 123 Reflective QoS Indication (RQI) information from the 5GC to the 124 5G-RG. 126 The 8 byte RFC 2516 data packet header is the most frugal of the 127 encapsulations that are currently supported by legacy access 128 equipment that can also meet all the requirements. 130 1.1. Requirements Language 132 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 133 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 134 document are to be interpreted as described in RFC 2119 [RFC2119]. 136 1.2. Acronyms 138 This document uses the following acronyms: 140 DSLAM Digital Subscriber Loop Access Multiplexer 141 F-AGF Fixed Network Access Gateway Function 142 FMC Fixed Mobile Convergence 143 IPoE IP over Ethernet 144 NAS Non-Access Stratum 145 OLT Optical Line Termination 146 PPPoE PPP over Ethernet 147 QFI QoS Flow Identifier 148 RG Residential Gateway 149 RQI Reflective QoS Indicator 151 2. Data Encapsulation Format 153 PPPoE data packet encapsulation is indicated in an IEEE 802[8] 154 Ethernet frame by an ethertype of 0x8864. The information following 155 that ethertype for the repurposing of the PPPoE data encapsulation 156 as the 5G FMC user plane encapsulation uses a value of 2 in the VER 157 field. The 5G FMC User Plane encapsulation is structured as follows: 159 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 1 160 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 161 | VER | TYPE | QFI |R|0| SESSION_ID | 162 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 163 | LENGTH | PROTOCOL ID | 164 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 165 | DATA PAYLOAD ~ 166 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- 168 The description of each field is as follows: 169 VER is the version. It MUST be set to 2. 171 TYPE is the message type. It MUST be set to 1. 173 QFI encodes the 3GPP 5G QoS Flow Identifier to be used for 174 mapping 5G QoS to IP DSCP/802.1 P-bits[9]. 176 R (short for RQI) encodes the one bit Reflective QoS Indicator 178 0 indicates the bit(s) MUST be set to zero 180 SESSION_ID is a 16-bit unsigned integer. It is used to 181 distinguish different PDU sessions that are in the VLAN 182 delineated multiplex. 184 LENGTH is the length in bytes of the data payload including 185 the initial Protocol ID. 187 PROTOCOL ID is the 16 bit identifier of the data payload type 188 encoded as per RFC 2516. The following values are valid in 189 this field for 5G FMC use: 191 0x0021: IPv4 192 0x0031: Ethernet (referred to in PPP as "bridging") 194 0x0057: IPv6 196 DATA PAYLOAD is encoded as per the protocol ID. 198 3. Acknowledgements 200 This memo is a result of comprehensive discussions by the Broadband 201 Forum"s Wireline Wireless Convergence Work Area. 202 The authors would also like to thank Joel Halpern and Dirk Von Hugo 203 for their detailed review of this draft. 205 4. Security Considerations 207 5G NAS procedures used for session life cycle maintenance employ 208 ciphering and integrity protection therefore can be considered to be 209 a more secure session establishment discipline than existing RFC 210 2516 procedures, at least against man in the middle attacks. 211 The re-purposing of the RFC 2516 data encapsulation will not 212 circumvent existing anti-spoofing and other security procedures in 213 deployed equipment. The existing access equipment will be able to 214 identify fields that they normally process and police as per 215 existing RFC 2516 traffic. 216 Therefore the security of a fixed access network will be equivalent 217 or superior to current practice. 219 5. IANA Considerations 221 IANA is requested to create a registry on the Point-to-Point (PPP) 222 Protocol Field Assignments IANA Web page as follows: 223 Registry Name: PPP Over Ethernet Versions 224 Registration Procedure: Expert Review 225 References: [RFC2516] [this document] 227 VER Description Reference 228 ----- ----------------------------- ----------- 229 0 reserved [this document] 230 1 Classic PPPoE [RFC2516] 231 2 5G FMC User Plane Encapsulation [this document] 232 3-15 unassigned [this document] 233 IANA is requested to add [this document] as an additional reference 234 for Ethertype 0x8864 in the Ethertypes table on the IANA "IEEE 802 235 Numbers" web page. 237 6. References 238 6.1. Normative References 239 [1] Bradner, S., "Key words for use in RFCs to Indicate 240 Requirement Levels", BCP 14, RFC 2119, March 1997. 241 [2] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 242 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 243 May 2017, . 244 [3] "A Method for Transmitting PPP Over Ethernet (PPPoE)", 245 IETF RFC 2516, February 1999 247 6.2. Informative References 248 [4] 3rd Generation Partnership Project; Technical 249 Specification Group Services and System Aspects; 250 Procedures for the 5G System (Release 16), 3GPP TS23.502 251 [5] 3rd Generation Partnership Project; Technical 252 Specification Group Services and System Aspects; Study on 253 the Wireless and Wireline Convergence for the 5G system 254 architecture (Release 16), 3GPP TR23.716, November 2018 255 [6] "Migrating to Ethernet Based Broadband Aggregation", 256 Broadband Forum Technical Report: TR-101 issue 2, July 257 2011 258 [7] "Multi-service Broadband Network Architecture and Nodal 259 Requirements", Broadband Forum Technical Report: TR-178, 260 September 2014 261 [8] 802, IEEE, "IEEE Standard for Local and Metropolitan 262 Networks: Overview and Architecture", IEEE Std 802-2014. 263 [9] 3rd Generation Partnership Project; Technical 264 Specification Group Radio Access Network; NG-RAN; PDU 265 Session User Plane Protocol (Release 15), 3GPP TS38.415 266 [10] "IANA Considerations for PPPoE", IETF RFC 4937, June 2007 268 7. Authors' Addresses 269 Dave Allan (editor) 270 Ericsson 271 2455 Augustine Drive 272 San Jose, CA 95054 USA 273 Email: david.i.allan@ericsson.com 275 Donald E. Eastlake 3rd 276 Futurewei Technologies 277 1424 Pro Shop Court 278 Davenport, FL 33896 USA 279 Phone: +1-508-333-2270 280 Email: d3e3e3@gmail.com 282 David Woolley 283 Telstra Corporation 284 242 Exhibition St 285 Melbourne, 3000 286 Australia 287 Email: david.woolley@team.telstra.com