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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 Distributed Mobility Management Kyoungjae Sun 2 Internet Draft Younghan Kim 3 Intended status: Informational Soongsil University 4 Expires: December 2017 Jaehwoon Lee 5 Dongguk University 6 June 28, 2017 8 Gap Analysis for Adapting the Distributed Mobility Management 9 Models in 4G/5G Mobile Networks 10 draft-kjsun-dmm-gap-analysis-3gpp-01.txt 12 Status of this Memo 14 This Internet-Draft is submitted in full conformance with the 15 provisions of BCP 78 and BCP 79. 17 Internet-Drafts are working documents of the Internet Engineering 18 Task Force (IETF). Note that other groups may also distribute 19 working documents as Internet-Drafts. The list of current Internet- 20 Drafts is at http://datatracker.ietf.org/drafts/current/. 22 Internet-Drafts are draft documents valid for a maximum of six 23 months and may be updated, replaced, or obsoleted by other documents 24 at any time. It is inappropriate to use Internet-Drafts as 25 reference material or to cite them other than as "work in progress." 27 This Internet-Draft will expire on December 27, 2017. 29 Copyright Notice 31 Copyright (c) 2017 IETF Trust and the persons identified as the 32 document authors. All rights reserved. 34 This document is subject to BCP 78 and the IETF Trust's Legal 35 Provisions Relating to IETF Documents 36 (http://trustee.ietf.org/license-info) in effect on the date of 37 publication of this document. Please review these documents 38 carefully, as they describe your rights and restrictions with 39 respect to this document. Code Components extracted from this 40 document must include Simplified BSD License text as described in 41 Section 4.e of the Trust Legal Provisions and are provided without 42 warranty as described in the Simplified BSD License. 44 Abstract 46 In this document, we provide a gap analysis to apply DMM deplyment 47 models to a 3GPP mobile core network. The DMM deployment models are 48 described into five models for separation control and data plane, 49 and the 3GPP mobile core network is a 4G-based extended architecture 50 and 5G core network study architecture. We conduct the gap analysis 51 to describe the technology that requires current standards-based 52 applicability and extension for technical interoperability between 53 two standardization organizations. 55 Table of Contents 57 1. Introduction ................................................ 2 58 2. 3GPP 4G/5G Studies Overview ................................. 3 59 3. Gap Analysis for Adapting DMM in 4G/5G Mobile Core Network .. 4 60 3.1. Split Home Anchor Model ................................ 4 61 3.2. Separated Control and User Plane ....................... 5 62 3.3. Centralized Control Plane .............................. 5 63 3.4. Data Plane Abstraction ................................. 6 64 3.5. On-demand Control Plane Orchestration .................. 6 65 3.6. Mapping DMM Deployment Model in to 4G/5G Core Network 66 Architecture ........................................... 7 67 4. Security Considerations...................................... 7 68 5. IANA Considerations ......................................... 7 69 6. References .................................................. 8 70 6.1. Normative References.................................... 8 71 6.2. Informative References.................................. 8 72 7. Acknowledgments ..............................................8 74 1. Introduction 76 The Distributed Mobility Management (DMM) solution has been 77 investigated to re-locate the current anchor functions in a 78 distributed manner and to provide different IP session management 79 characteristics for each mobile node session. For deploying DMM, 80 five different models are described in [dmm-deployment-models] based 81 on the network entities according to the location(access or home) 82 and functionality(control or data). 84 3GPP has the responsibility to standardize cellular mobile networks, 85 and the functional separation of the gateway in 4G Evolved Packet 86 Core(EPC) netowrk has also been studied to divide the gateway into 87 a control and data plane, defining an interface between them, and 88 configuring a data path from the control plane entities to the data 89 plane entities by exchanging signaling messages between the control 90 plane entities. Futhermore, future mobile core network architecture 91 called 5G NextGen has been also studied. For flexible service 92 continuity, 5G NextGen have integrated the current distributed 93 gateway entities (SGW and PGW) that are deployed in a hierarchical 94 manner into a combined gateway to separate the control and data 95 plane function. In addition, to provide on-demand session 96 management, they separate the attachment procedure of the mobile 97 node and the session establishment procedure so that different 98 sessions of the mobile node with different service characteristics 99 can connect through a network slice. However, mobility management 100 solution when the IP anchor function is changing is not decribed 101 clearly yet. 103 This document provides a gap analysis to adapt the DMM deployment 104 model into the 4G/5G mobile network architectures studied in 3GPP. 105 Based on studies of the network architecture evolution in 3GPP, we 106 analyze whether each scenario of the DMM deployment model can be 107 adapted to the 3GPP network architecture under study by showing the 108 corresponding mapping table. 110 2. 3GPP 4G/5G Studies Overview 112 The 4G EPC network includes several components that provide IP 113 connectivity to mobile subscribers and accommodate the use of 114 various network access technologies. In mobility management, many 115 different kinds of handover can occur in the EPC network 116 architecture. IP mobility is occurred in the Inter-MME handover, 117 which occurs between different SGWs, the traffic forwarding path 118 between the SGW and PGW should be changed, so the IP mobility scheme 119 should be needed. For this, the 3GPP standard can use the GTP or 120 PMIP protocol to update the location of the mobile node, establish 121 the tunnel between the SGW and PGW, and forward data traffic. 123 To improve the flexibility during deployment and operation of the 124 mobile core network, 3GPP provides several options to modify the 125 gateway deployment. First, the combined gateway entity is defined 126 by integrating the SGW and PGW function into a single component in 127 [3GPP TR 23.401]. Second, the control plane and the data plane are 128 separated for the gateway functions in [3GPP TR 23.714]. The 129 operation of the interface between control plane and data plane 130 includes managing the state of the data plane in the control plane, 131 configuring the session path between the GW-DPs according to the 132 service request of the mobile node, and reporting the measurement 133 information from the data plane to the control plane. 135 +-----+ +-----+ +-----+ +-----+ +----+ 136 | NEF | | NRF | | PCI | | UDM | | AF | 137 +-----+ +-----+ +-----+ +-----+ +----+ 138 | | | | | 139 ----------------------------------------------- 140 | | | 141 +-----+ +-----+ +-----+ 142 | AUF | | AMF | | SMF | 143 +-----+ +-----+ +-----+ 144 : : : control-plane 145 ==============:=====:=============:==================== 146 : : : user-plane 147 +----+ +-----+ +-----+ +----+ 148 | UE |----| RAN |---------| UPF |-------| DN | 149 +----+ +-----+ +-----+ +----+ 151 Fig 1. 5G Core Network Architecture 153 The 5G mobile core network architecture is designed in a service- 154 oriented manner described in Fig.1. 5G mobile core network design 155 separates control and user plane functions for allowing independent 156 scaling of both functions and it allows control plane dynamically 157 configures user-plane functions to provide the traffic handling 158 functionality. Unlike SGW/PGW in 4G network, user plane function of 159 5G is defined as a unified entitiy. All the control plane functions 160 are separated into different standlone entities to enable 161 independent scalability and flexibility. For example, unlike the 4G 162 mobile core network, authemtication and mobility management funtion 163 which were combined into the MME are separated and also mobility 164 management and session management function are separated. The 165 interfaces between control functions are defined as a service-based 166 interface which is independent on the communication protocol so that 167 the interoperation in the control plane is more flexible that the 4G 168 mobile core network. 170 For the mobility management, since that mobility managment and 171 session management functions are separated, they consider to support 172 different levels of data session continuity based on the mobility on 173 demand concept as similiar with DMM works. It allows selection of 174 anchor point to achieve efficient user plane path, as well as 175 enablement of reselection of anchor point to achieve efficient user 176 plane path with minimum service interruption. In the 5G mobile core 177 architecture, IP anchor function is separated into control and user 178 plane function. Control plane of anchor function which is allocation 179 of UE IP address is performed by the Session Management Function 180 (SMF) and user plane of anchor functions such as external PDU 181 session point, packet forwarding and anchor point for mobility are 182 assigned to user plane function. When the IP mobility of the mobile 183 nodes traffic occurs between the different access networks or by 184 changing the IP anchor in the core network, the SMF processes the 185 signaling to provide session mobility for the mobile node and 186 configures the forwarding policies to the data plane. There is more 187 than one data plane functions in the core network, and these are 188 included in the path of the mobile nodes traffic to the data network 189 but it may not perform the separate roles as with the SGW/PGW in the 190 existing 4G network. 192 3. Gap Analysis for Adapting DMM in 4G/5G Mobile Core Network 194 Following five deployment models in [dmm-deployment-model], we 195 provide a conformance and gap analysis to apply the IETF DMM 196 deployment model to 4G/5G mobile network architectures. Detailed 197 description of DMM deployment model is not provided in this 198 document. 200 3.1. Split Home Anchor Model 202 In the 4G EPC network, we can deploy the PGW as the home anchor with 203 CP/DP separation and the SGW as an Access Node with a legacy entity 204 without CP/DP separation. For that, terminology of Home-CPA is 205 mapped to PGW-CP, Home-DPA to PGW-DP, Access-CPN to SGW-CP, and 206 Access-CPN to SGW-DP. In this case, the current interface between 207 SGW and PGW is separated into two interfaces for the control and 208 data planes. However, since the SGW is implemented as an existing 209 CP/DP combined entity, the destinations of the control and data 210 packets must be set differently in the SGW. 212 In the 5G core network study architecture, the data plane functions 213 are not separated into Home and Access. Even though one or more data 214 plane functions may be included in the data traffic path of the 215 mobile node between the access network and the data network, it is 216 not clear whether this separates the roles of Access and Home. 218 3.2. Separated Control and User Plane 220 This model separates the control plane and the data plane from both 221 the Access and Home nodes, and it can be applied as a CP/DP 222 separation architecture between the SGW and the PGW when applied in 223 the 4G EPC network. The parameters for the tunnel configuration, 224 such as the TEID according to the bearer information generated 225 through the control plane and the QoS-related information, are 226 transmitted to the data plane by using the interface between the 227 control plane and the data plane, and traffic measurement 228 information is transmitted to the control plane for billing and 229 policy management. 231 Since there is no definition for an access node in the 5G core 232 architecture, we cannot find a clear adaptable scenario to apply 233 that model. By considering the network slice concept, the 5G 234 architecture separates the mobile node attachment and the service 235 request process for the authentication and connection state 236 management according to the attachment of the mobile node through 237 the Common CP function and selects an appropriate network slice when 238 the mobile node requests session connectivity to the network. In 239 this case, several control planes can exist in the core network, but 240 this is not related to mobility management and there is no data 241 plane function that is mapped with the Common CP. 243 3.3. Centralized Control Plane 245 In [3GPP TR 23.401], the 3GPP standard allows to 246 integrate the SGW and PGW into a single entity called Combined GW. 247 In the CP/DP separation architecture, each plane entity can be 248 deployed as a combined or separated entity, and the architecture 249 with a combined control plane and separate data plane entities can 250 be applied. For the combined GW-CP function, the interface between 251 control plane functions is no longer required because the SGW-CP and 252 PGW-CP functions are combined as a single physical entity. 254 With the 5G core architecture, there may be an architecture for a 255 single control plane entity to manage multiple data plane entities, 256 even without an access node definition. In particular, in a 258 multi-homed PDU scenario to manage multiple parallel PDU sessions, 259 [3GPP TR 23.799] defines a data plane branching a GW entity between 260 the access network and the different data plane functions. The 261 branching GW maintains the session between the respective anchor 262 data plane nodes and uses the tunnels for traffic forwarding. 264 3.4. Data Plane Abstraction 266 SDN-based EPC networks and forwarding configuration schemes between 267 the data plane entities can be possible. In several studies, all 268 EPC control plane functions, including the SGW-CP and the PGW-CP, 269 are implemented in the SDN controller as an SDN application, and the 270 data traffic path in the data plane network is set utilizing 271 southbound protocol such as the OpenFlow. The SDN-based EPC 272 architecture has an advantage in that the traffic path between the 273 data plane entities can be abstracted from the control plane while 274 maintaining each GW role, so a flexible forwarding path 275 configuration may be possible. 277 The 5G core network architecture document also considers SDN-based 278 data plane abstraction. Even though there is no definition for 279 Anchor and Access node, the data plane GW entities and the switches 280 in the core network are abstracted through the SDN controller to 281 manage the traffic path from the access network to the data network. 283 3.5. On-demand Control Plane Orchestration 285 This model can be deployed through an EPC network structure with an 286 NFV-based virtualization environment and Management & Orchestration 287 (MANO) function. In an NFV-based virtualized EPC (vEPC) environment, 288 all control plane functions can be installed on a general-purpose 289 cloud server using a Virtualized Network Function (VNF), and the 290 data plane entities can be physically located in the switch or 291 router. Regarding mobility, the Mobility Controller defined in the 292 DMM deployment model is an entity that provides mapping information 293 of the mobility control plane and data plane functions as needed. 294 This is a method to generate mobility services by including VNFs 295 according to the mobility in the network. 297 The 5G architecture research also discusses methods to provide 298 on-demand services in a virtualization-based environment. In 299 particular, different sets of core network functions by selecting 300 network slices according to the type of traffic for a given service, 301 even if they are from the same mobile node. A network slice has the 303 advantage of providing QoS to meet various service requirements. 304 Although the reference architecture for 5G networks has been 305 defined, a real deployment model and its details are still under 306 consideration. 308 3.6. Mapping DMM Deployment Model in to 4G/5G Core Network Architecture 310 Table 1 shows whether five DMM deployment models are applicable to 311 the 4G EPC network and 5G core network study architecture. 313 +==============+===================================================+ 314 | | DMM Deployment Models (Described Chapter) | 315 | 3GPP +---------------------------------------------------+ 316 | | 3.1 | 3.2 | 3.3 | 3.4 | 3.5 | 317 +========================+=========+=========+==========+==========+ 318 | 4G EPC Core | | | | YES | YES | 319 | with CP/DP | YES | YES | YES | with | with | 320 | Separation | | | | SDN | NFV | 321 +--------------+---------+---------+---------+----------+----------+ 322 | 5G Core | | | | YES | YES | 323 | Network Study| NO | NO | YES | with | with | 324 | Architecture | | | | SDN | NFV | 325 +==============+=========+=========+=========+==========+==========+ 326 Table 1: Mapping DMM Deployment Model in to 3GPP Mobile Core Network 328 4. Security Considerations 330 T.B.D 332 5. IANA Considerations 334 T.B.D 336 6. References 338 6.1. Normative References 340 [dmm-deployment-models] S. Gundavelli, and S. Jeon, "DMM Deployment 341 Models and Architectural Considerations", I.D. draft-ietf 342 -dmm-deployment-models-01, Feb. 2017. 344 [3GPP TR 23.401] 3GPP, "LTE: General Packet Radio Service(GPRS) 345 enhancements for Evolved Universal Terrestrial Radio 346 Access Network (E-UTRAN) access", 3GPP TR 23.401 347 (v.14.2.0), Dec. 2016. 349 [3GPP TR 23.714] 3GPP, "Study on Control and User Plane 350 Separation of EPC nodes", 3GPP TR 23.714 (v.14.0.0). 351 Jun.2016. 353 [3GPP TR 23.799] 3GPP, "Study on Architecture for Next Generation 354 System", 3GPP TR 23.799 (v.1.0.2), Sep. 2016. 356 6.2. Informative References 358 7. Acknowledgments 359 Authors' Addresses 361 Kyoungjae Sun 362 Soongsil University 363 369, Sangdo-ro, Dongjak-gu 364 Seoul 156-743, Korea 366 Email: gomjae@ssu.ac.kr 368 Jaehwoon Lee 369 Dongguk University 370 26, 3-ga Pil-dong, Chung-gu 371 Seoul 100-715, KOREA 373 Email: jaehwoon@dongguk.edu 375 Younghan Kim 376 Soongsil University 377 369, Sangdo-ro, Dongjak-gu 378 Seoul 156-743, Korea 380 Email: younghak@dcn.ssu.ac.kr