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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Service Function Chaining P. A. Aranda 3 INTERNET-DRAFT D. Lopez 4 Intended Status: Informational Telefonica I+D 5 W. Haeffner 6 Vodafone 8 Expires: April 7, 2016 October 5, 2015 10 Service Function Chaining Dataplane Elements in Mobile Networks 11 draft-aranda-sf-dp-mobile-00 13 Abstract 15 The evolution of the network towards 5G implies a challenge for the 16 infrastructure. The targeted services and the full deployment of 17 virtualization in all segments of the network will need service 18 function chains that previously resided in the(local and remote) 19 infrastructure of the Network operators to extend to the radio access 20 network (RAN). 22 The objective of this draft is to provide a non-exhaustive but 23 representative list of service functions in 4G and 5G networks. We 24 base on the problem statement [RFC 7498] and architecture framework 25 [SFC-Arch] of the working group, as well on the existing mobile 26 networks use cases [SFC-mobile-uc] and the requirement gathering 27 process of different initiatives around the world [5GPPP, IMT2020, 28 5G-FK, IMT2020-CN ] to anticipate network elements that will be 29 needed in 5G networks. 31 Status of this Memo 33 This Internet-Draft is submitted to IETF in full conformance with the 34 provisions of BCP 78 and BCP 79. 36 Internet-Drafts are working documents of the Internet Engineering 37 Task Force (IETF), its areas, and its working groups. Note that 38 other groups may also distribute working documents as 39 Internet-Drafts. 41 Internet-Drafts are draft documents valid for a maximum of six months 42 and may be updated, replaced, or obsoleted by other documents at any 43 time. It is inappropriate to use Internet-Drafts as reference 44 material or to cite them other than as "work in progress." 45 The list of current Internet-Drafts can be accessed at 46 http://www.ietf.org/1id-abstracts.html 48 The list of Internet-Draft Shadow Directories can be accessed at 49 http://www.ietf.org/shadow.html 51 Copyright and License Notice 53 Copyright (c) 2015 IETF Trust and the persons identified as the 54 document authors. All rights reserved. 56 This document is subject to BCP 78 and the IETF Trust's Legal 57 Provisions Relating to IETF Documents 58 (http://trustee.ietf.org/license-info) in effect on the date of 59 publication of this document. Please review these documents 60 carefully, as they describe your rights and restrictions with respect 61 to this document. Code Components extracted from this document must 62 include Simplified BSD License text as described in Section 4.e of 63 the Trust Legal Provisions and are provided without warranty as 64 described in the Simplified BSD License. 66 Table of Contents 68 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 69 1.1 Terminology and abbreviations . . . . . . . . . . . . . . . 3 70 1.2 General scope of mobile service chains . . . . . . . . . . 3 71 1.3 Requirements for 5G networks . . . . . . . . . . . . . . . 4 72 1.4 Evolution of the end-to-end carrier network . . . . . . . . 4 73 2. Mobile network overview . . . . . . . . . . . . . . . . . . . . 5 74 2.1. Building blocks of 4G and 5G networks . . . . . . . . . . . 5 75 2.2. Overview of mobile service chain elements in 4G networks 76 and their evolution in 5G . . . . . . . . . . . . . . . . . 6 77 2.3 Classification schemes for 5G networks . . . . . . . . . . . 7 78 3 Control plane considerations . . . . . . . . . . . . . . . . . . 7 79 4 Operator requirements . . . . . . . . . . . . . . . . . . . . . 7 80 5 Security Considerations . . . . . . . . . . . . . . . . . . . . 9 81 6 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 9 82 7 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 9 83 8 References . . . . . . . . . . . . . . . . . . . . . . . . . . 9 84 8.1 Normative References . . . . . . . . . . . . . . . . . . . 9 85 8.2 Informative References . . . . . . . . . . . . . . . . . . 9 86 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11 88 1 Introduction 90 92 1.1 Terminology and abbreviations 94 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 95 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 96 document are to be interpreted as described in RFC 2119 [RFC2119]. 98 Much of the terminology used in this document has been defined by 99 either the 3rd Generation Partnership Project (3GPP) or by activities 100 related to 5G networks like ITU-T's IMT2020. Some terms are defined 101 here for convenience, in addition to those found in [RFC6459]. 103 UE User equipment like tablets or smartphones 104 eNB enhanced NodeB, radio access part of the LTE system 105 S-GW Serving Gateway, primary function is user plane mobility 106 P-GW Packet Gateway, actual service creation point, terminates 3GPP 107 mobile network, interface to Packet Data Networks (PDN) 108 HSS Home Subscriber Server (control plane element) 109 MME Mobility Management Entity (control plane element) 110 GTP GPRS (General Packet Radio Service) Tunnel Protocol 111 S-IP Source IP address 112 D-IP Destination IP address 113 IMSI The International Mobile Subscriber Identity that identifies a 114 mobile subscriber 115 (S)Gi Egress termination point of the mobile network (SGi in case of 116 LTE, Gi in case of UMTS/HSPA). The internal data structure of 117 this interface is not standardized by 3GPP 118 PCRF 3GPP standardized Policy and Charging Rules Function 119 PCEF Policy and Charging Enforcement Function 120 TDF Traffic Detection Function 121 TSSF Traffic Steering Support Function 122 IDS Intrusion Detection System 123 FW Firewall 124 ACL Access Control List 125 PEP Performance Enhancement Proxy 126 IMS IP Multimedia Subsystem 127 LI Legal Intercept 129 1.2 General scope of mobile service chains 131 Current mobile access networks terminate at a mobile service creation 132 point (called Packet Gateway) typically located at the edge of an 133 operator IP backbone. Within the mobile network, the user payload is 134 encapsulated in 3GPP specific tunnels terminating eventually at the 135 P-GW. In many cases application-specific IP traffic is not directly 136 exchanged between the original mobile network, more specific the P- 137 GW, and an application platform, but will be forced to pass a set of 138 service functions. Network operators use these service functions to 139 differentiate their services. 141 In order to cope with the stringent requirements of 5G networks (cf. 142 Section 1.3), we expect a new architecture to appear. This 143 architecture will surely make extensive use of virtualisation up to 144 the RAN. We also expect that IP packets will need to be processed 145 much earlier that in the current 3GPP architecture. In this context, 146 it is foreseeable that Service Function Chaining will play a 147 substantial role when managing the chains network traffic will 148 traverse. We also expect new kinds of service functions specific to 149 the radio access part to appear and that these new service functions 150 will need to be managed by the SFC management infrastructure of the 151 operator. 153 1.3 Requirements for 5G networks 155 As set forth by the 5G-PPP [5GPPP], the evolution of the 156 infrastructure towards 5G should enable the following features in the 157 mobile environment: 158 o Providing 1000 times higher wireless area capacity 159 o Saving up to 90% of energy per service provided 160 o Reducing the average service creation time cycle from 90 hours to 161 90 minutes 162 o Facilitating very dense deployments of wireless communication links 163 to connect over 7 trillion wireless devices serving over 7 billion 164 people 166 1.4 Evolution of the end-to-end carrier network 168 [SFC-Mobile-UC] presents the structure of end-to-end carrier 169 networks and focused on the Service Function Chaining use cases for 170 mobile carrier networks, such as current 3GPP- based networks. We 171 recognise that other types of carrier networks that are currently 172 deployed share similarities in the structure of the access networks 173 and the service functions with mobile networks. The evolution towards 174 5G networks will make the distinction between these different types 175 of networks blur and eventually disappear. 177 5G networks are expected to massively deploy virtualisation 178 technologies from the radio elements to the core of the network. The 179 four building blocks of the RAN, i.e. i) spectrum allocation or 180 physical layer (PHY), i) Medium Access Control (MAC), iii) Radio Link 181 Control (RLC) and iv) Packet Data Convergence, are candidates for 182 virtualisation. 184 2. Mobile network overview 186 [SFC-Mobile-UC] provides an overview of mobile networks up to LTE 187 (Long Term Evolution) networks. As the specifications mature, we will 188 provide the updates to the LTE architecture. 190 2.1. Building blocks of 4G and 5G networks 192 The major functional components of an LTE network are shown in Figure 193 2 and include user equipment (UE) like smartphones or tablets, the 194 LTE radio unit named enhanced NodeB (eNB), the serving gateway (S-GW) 195 which together with the mobility management entity (MME) takes care 196 of mobility and the packet gateway (P-GW), which finally terminates 197 the actual mobile service. These elements are described in detail in 198 [TS.23.401]. Other important components are the home subscriber 199 system (HSS), the Policy and Charging Rule Function (PCRF) and the 200 optional components: the Traffic Detection Function (TDF) and the 201 Traffic Steering Support Function (TSSF), which are described in 202 [TS.23.203]. The P-GW interface towards the SGi-LAN is called the 203 SGi-interface, which is described in [TS.29.061]. The TDF resides on 204 this interface. Finally, the SGi-LAN is the home of service function 205 chains (SFC), which are not standardized by 3GPP. 207 +--------------------------------------------+ 208 | Control Plane (C) [HSS] | [OTT Appl. Platform] 209 | | | | 210 | +--------[MME] [PCRF]--+--------+ Internet 211 | | | | | | | 212 | [UE-C] -- [eNB-C] == [S-GW-C] == [P-GW-C] | | | 213 +=====|=========|==========|============|====+ +-----+----+-------+ 214 | | | | | | | | | | 215 | [UE-U] -- [eNB-U] == [S-GW-U] == [P-GW-U]-+--+----[SGi-LAN] | 216 | | | | | 217 | | | | | 218 | | | [Appl. Platform] | 219 | | | | 220 | User Plane (U) | | | 221 +--------------------------------------------+ +------------------+ 223 |<----------- 3GPP Mobile Network ---------->| |<-- IP Backbone ->| 225 Figure 2: End to end context including all major components of an LTE 226 network. Source [SFC-Mobile-UC] 228 The radio-based IP traffic between the UE and the eNB is encrypted 229 according to 3GPP standards. Between the eNB, S-GW and P-GW user 230 plane IP packets are encapsulated in 3GPP-specific tunnels. In some 231 mobile carrier networks the 3GPP-specific tunnels between eNB and S- 232 GW are even additionally IPSec-encrypted. More precisely, IPSec 233 originates/ terminates at the eNB and on the other side at an IPSec- 234 GW often placed just in front of the S-GW. For more details see 235 [TS.29.281], [TS.29.274] and [TS.33.210]. 237 In this context, service function chains will not only act on user 238 plane IP traffic, but also on the traffic in RAN. The way these will 239 act on user traffic may depend not only depend on subscriber, service 240 or network specific control plane metadata, but also on the state of 241 the network at the particular location of the user. 243 2.2. Overview of mobile service chain elements in 4G networks and their 244 evolution in 5G 246 [SFC-Mobile-UC] provides an overview of the service chain elements in 247 4G networks. Figure 3, extracted from it, shows the service chain 248 topology in such networks. 250 +------------------------------------------------------------------+ 251 | Control Plane Environment [HSS] [MME] [PCRF] [others] | 252 +------------------------------------------------|-----------------+ 253 +--------------------+ 254 +---------------------------|--------------------|-----------------+ 255 | User Plane Environment | | | 256 | | /------(S)Gi-LAN --+-----\ | 257 | | | | | 258 | | | +---[SF1]-[SF3]-[SF5]---[Appl. 1] | 259 | | | / | | 260 | [UE]---[eNB]===[S-GW]===[P-GW/TDF]--[SF2]-[SF4]-[SF6]-------+ | 261 | | \ | | | 262 | | +---[SF7]-[SF8]-[SF9]-----+ | | 263 | | | | | | 264 | \------------------------/ | | | 265 | | | | 266 +----------------------------------------------------------|--|----+ 267 | | 268 OTT Internet Applications 269 | | 270 [Appl. 2] [Appl. 3] 272 Figure 3: Typical service chain topology. 274 Service Functions handle session flows between mobile user equipment 275 and application platforms. Control plane metadata supporting policy 276 based traffic handling may be linked to individual service functions. 277 In 5G networks, we expect the packet gateway (P-GW) to loose its 278 central position and be integrated with functions in the RAN. Radio 279 Resource Control (RRC) in 5G network will be integrated into the 280 Control Plane environment. 282 2.3 Classification schemes for 5G networks 284 TBD: We expect classification schemes for 5G networks to evolve as 285 the standards appear. 287 3 Control plane considerations TBD: We except the RRC to be integrated 288 with the SFC Control plane in 5G. 290 4 Operator requirements 292 4G mobile operators use service function chains to enable and 293 optimize service delivery, offer network related customer services, 294 optimize network behavior or protect networks against attacks and 295 ensure privacy. Service function chains are essential to their 296 business. Without these, mobile operators are not able to deliver the 297 necessary and contracted Quality of Experience (QoE) or even certain 298 products to their customers. 300 As set forth by the 5G-PPP [5GPPP], the evolution of the 301 infrastructure towards 5G should enable the following features in the 302 mobile environment: 304 o Providing 1000 times higher wireless area capacity 306 o Saving up to 90% of energy per service provided 308 o Reducing the average service creation time cycle from 90 hours to 309 90 minutes 311 o Facilitating very dense deployments of wireless communication links 312 to connect over 7 trillion wireless devices serving over 7 billion 313 people 315 To meet these additional requirements, operators will need to make an 316 extensive use of service chains and to extend their scope to 317 functions in the Radio Access Network. 319 5 Security Considerations 321 Organizational security policies must apply to ensure the integrity 322 of the SFC environment. SFC will very likely handle user traffic and 323 user specific information in greater detail than the current service 324 environments do today. This is reflected in the considerations of 325 carrying more metadata through the service chains and the control 326 systems of the service chains. This metadata will contain sensitive 327 information about the user and the environment in which the user is 328 situated. This will require proper considerations in the design, 329 implementation and operations of such environments to preserve the 330 privacy of the user and also the integrity of the provided metadata. 332 6 IANA Considerations 334 This document has no actions for IANA. 336 7 Acknowledgements 338 This work has been partially performed in the scope of the 339 SUPERFLUIDITY project, which has received funding from the European 340 Union's Horizon 2020 research and innovation programme under grant 341 agreement No.671566 (Research and Innovation Action) 343 8 References 345 8.1 Normative References 347 [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate 348 Requirement Levels", BCP 14, RFC 2119, DOI 349 10.17487/RFC2119, March 1997, . 352 8.2 Informative References 354 [RFC6459] Korhonen, J., Ed., Soininen, J., Patil, B., Savolainen, 355 T., Bajko, G., and K. Iisakkila, "IPv6 in 3rd Generation 356 Partnership Project (3GPP) Evolved Packet System (EPS)", 357 RFC 6459, DOI 10.17487/RFC6459, January 2012, 358 . 360 [RFC6733] Fajardo, V., Ed., Arkko, J., Loughney, J., and G. Zorn, 361 Ed., "Diameter Base Protocol", RFC 6733, DOI 362 10.17487/RFC6733, October 2012, . 365 [RFC7498] Quinn, P., Ed., and T. Nadeau, Ed., "Problem Statement for 366 Service Function Chaining", RFC 7498, DOI 367 10.17487/RFC7498, April 2015, . 370 [TS.23.003] "Numbering, addressing and identification", 3GPP TS 371 23.003 13.2.0, July 2015. 373 [TS.23.203] "Policy and charging control architecture", 3GPP TS 374 23.203 13.4.0, July 2015. 376 [TS.23.401] "General Packet Radio Service (GPRS) enhancements for 377 Evolved Universal Terrestrial Radio Access Network (E- 378 UTRAN) access", 3GPP TS 23.401 13.3.0, July 2015. 380 [TS.29.061] "Interworking between the Public Land Mobile 381 Network(PLMN) supporting packet based services and Packet 382 Data Networks (PDN)", 3GPP TS 29.061 13.0.0, March 2015. 384 [TS.29.212] "3GPP Evolved Packet System (EPS); Evolved General Packet 385 Radio Service (GPRS) Tunneling Protocol for Control plane 386 (GTPv2-C); Stage 3", 3GPP TS 29.212 13.2.0, July 2015. 388 [TS.29.274] "3GPP Evolved Packet System (EPS); Evolved General Packet 389 Radio Service (GPRS) Tunneling Protocol for Control plane 390 (GTPv2-C); Stage 3", 3GPP TS 29.274 12.3.0, December 2013. 392 [TS.29.281] "General Packet Radio System (GPRS) Tunneling 393 ProtocolUser Plane (GTPv1-U)", 3GPP TS 29.281 12.1.0, 394 January 2015. 396 [TS.33.210] "3G security; Network Domain Security (NDS); IP network 397 layer security",3GPP TS 33.210 12.2.0, December 2012 399 [SFC-Arch] Halpern, J. and C. Pignataro, "Service Function Chaining 400 (SFC) Architecture", draft-ietf-sfc-architecture-09 (work 401 in progress), June 2015. 403 [SFC-DC-UC] Kumar, S., Tufail, M., Majee, S., Captari, C., and S. 404 Homma, "Service Function Chaining Use Cases In Data 405 Centers", draft-ietf-sfc-dc-use-cases-03 (work in 406 progress), July 2015. 408 [5GPPP] The 5G Infrastructure Public Private Partnership, 409 https://5g-ppp.eu 411 [IMT2020] ITU towards 'IMT for 2020and beyond', 412 http://www.itu.int/en/ITU-R/study-groups/rsg5/rwp5d/imt- 413 2020/Pages/default.aspx 415 [5G-FK] 5G Forum Korea home page, http://www.5gforum.org/#!eng/cvb1 417 [IMT2020-CN] IMT2020 (5G) Promotion Group China home page, 418 http://www.imt-2020.cn/en/introduction 420 Authors' Addresses 422 Pedro A. Aranda Gutierrez 423 Telefonica I+D 424 Zurbaran, 12 425 Madrid 28010 426 ES 428 Phone: +34 913 129 566 429 Email: pedroa.aranda@telefonica.com 431 Diego R. Lopez 432 Telefonica I+D 433 Zurbaran, 12 434 Madrid 28010 435 ES 437 Phone: +34 913 129 041 438 Email: diego@tid.es 440 Walter Haeffner 441 Vodafone 442 Vodafone D2 GmbH 443 Ferdinand-Braun-Platz 1 444 Duesseldorf 40549 445 DE 447 Phone: +49 (0)172 663 7184 448 Email: walter.haeffner@vodafone.com