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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 ICN Research Group Prakash Suthar 3 Internet-Draft Milan Stolic 4 Intended status: Informational Anil Jangam, Ed. 5 Expires: April 25, 2019 Cisco Systems 6 Dirk Trossen 7 InterDigital Inc. 8 Ravishankar Ravindran 9 Huawei Technologies 10 October 22, 2018 12 Native Deployment of ICN in LTE, 4G Mobile Networks 13 draft-irtf-icnrg-icn-lte-4g-02 15 Abstract 17 LTE, 4G mobile networks use IP based transport for control plane to 18 establish the data session and user plane for actual data delivery. 19 In existing architecture, IP transport used in user plane is not 20 optimized for data transport, which leads to an inefficient data 21 delivery. IP unicast routing from server to clients is used for 22 delivery of multimedia content to User Equipment (UE), where each 23 user gets a separate stream. From bandwidth and routing perspective 24 this approach is inefficient. Multicast and broadcast technologies 25 have emerged recently for mobile networks, but their deployments are 26 very limited or at an experimental stage due to complex architecture 27 and radio spectrum issues. ICN is a rapidly emerging technology with 28 built-in features for efficient multimedia data delivery, however 29 majority of the work is focused on fixed networks. The main focus of 30 this draft is on native deployment of ICN in cellular mobile networks 31 by using ICN in 3GPP protocol stack. ICN has an inherent capability 32 for multicast, anchorless mobility, security and it is optimized for 33 data delivery using local caching at the edge. The proposed 34 approaches in this draft allow ICN to be enabled natively over the 35 current LTE stack comprising of PDCP/RLC/MAC/PHY or in a dual stack 36 mode (along with IP) help optimize the mobile networks by leveraging 37 the inherent benefits of ICN. 39 Status of This Memo 41 This Internet-Draft is submitted in full conformance with the 42 provisions of BCP 78 and BCP 79. 44 Internet-Drafts are working documents of the Internet Engineering 45 Task Force (IETF). Note that other groups may also distribute 46 working documents as Internet-Drafts. The list of current Internet- 47 Drafts is at https://datatracker.ietf.org/drafts/current/. 49 Internet-Drafts are draft documents valid for a maximum of six months 50 and may be updated, replaced, or obsoleted by other documents at any 51 time. It is inappropriate to use Internet-Drafts as reference 52 material or to cite them other than as "work in progress." 54 This Internet-Draft will expire on April 25, 2019. 56 Copyright Notice 58 Copyright (c) 2018 IETF Trust and the persons identified as the 59 document authors. All rights reserved. 61 This document is subject to BCP 78 and the IETF Trust's Legal 62 Provisions Relating to IETF Documents 63 (https://trustee.ietf.org/license-info) in effect on the date of 64 publication of this document. Please review these documents 65 carefully, as they describe your rights and restrictions with respect 66 to this document. Code Components extracted from this document must 67 include Simplified BSD License text as described in Section 4.e of 68 the Trust Legal Provisions and are provided without warranty as 69 described in the Simplified BSD License. 71 Table of Contents 73 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 74 1.1. Conventions and Terminology . . . . . . . . . . . . . . . 3 75 1.2. 3GPP Terminology and Concepts . . . . . . . . . . . . . . 3 76 2. LTE, 4G Mobile Network . . . . . . . . . . . . . . . . . . . 7 77 2.1. Network Overview . . . . . . . . . . . . . . . . . . . . 7 78 2.2. QoS Challenges . . . . . . . . . . . . . . . . . . . . . 9 79 2.3. Data Transport Using IP . . . . . . . . . . . . . . . . . 10 80 2.4. Virtualizing Mobile Networks . . . . . . . . . . . . . . 11 81 3. Data Transport Using ICN . . . . . . . . . . . . . . . . . . 11 82 4. ICN Deployment in 4G and LTE Networks . . . . . . . . . . . . 14 83 4.1. General ICN Deployment Considerations . . . . . . . . . . 14 84 4.2. ICN Deployment Scenarios . . . . . . . . . . . . . . . . 14 85 4.3. ICN Deployment in LTE Control Plane . . . . . . . . . . . 17 86 4.4. ICN Deployment in LTE User Plane . . . . . . . . . . . . 19 87 4.4.1. Dual stack ICN Deployments in UE . . . . . . . . . . 19 88 4.4.2. Native ICN Deployments in UE . . . . . . . . . . . . 22 89 4.5. ICN Deployment in eNodeB . . . . . . . . . . . . . . . . 23 90 4.6. ICN Deployment in Packet Core (SGW, PGW) Gateways . . . . 25 91 4.7. Lab Testing . . . . . . . . . . . . . . . . . . . . . . . 27 92 5. Security Considerations . . . . . . . . . . . . . . . . . . . 28 93 6. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 94 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 30 95 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 30 96 8.1. Normative References . . . . . . . . . . . . . . . . . . 30 97 8.2. Informative References . . . . . . . . . . . . . . . . . 31 98 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 35 100 1. Introduction 102 LTE mobile technology is built as all-IP network. It uses IP routing 103 protocols such as OSPF, ISIS, BGP etc. to establish network routes to 104 route the data traffic to end user's device. Stickiness of IP 105 address to a device is the key to get connected to a mobile network 106 and the same IP address is maintained through the session until the 107 device gets detached or moves to another network. 109 One of the key protocols used in 4G and LTE networks is GPRS 110 Tunneling protocol (GTP). GTP, DIAMETER and other protocols are 111 built on top of IP. One of the biggest challenges with IP based 112 routing is that it is not optimized for data transport although it is 113 the most efficient communication protocol. By native implementation 114 of Information Centric Networking (ICN) in 3GPP, we can re-architect 115 mobile network and optimize its design for efficient data transport 116 by leveraging the caching feature of ICN. ICN also offers an 117 opportunity to leverage inherent capabilities of multicast, 118 anchorless mobility management, and authentication. This draft 119 provides insight into different options for deploying ICN in mobile 120 networks and how they impact mobile providers and end-users. 122 1.1. Conventions and Terminology 124 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 125 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 126 document are to be interpreted as described in [RFC2119]. 128 1.2. 3GPP Terminology and Concepts 130 1. Access Point Name 132 The Access Point Name (APN) is a Fully Qualified Domain Name 133 (FQDN) and resolves to a set of gateways in an operator's 134 network. APN identifies the packet data network (PDN) that a 135 mobile data user wants to communicate with. In addition to 136 identifying a PDN, an APN may also be used to define the type of 137 service, QoS and other logical entities inside GGSN, PGW. 139 2. Control Plane 141 The control plane carries signaling traffic and is responsible 142 for routing between eNodeB and MME, MME and HSS, MME and SGW, 143 SGW and PGW etc. Control plane signaling is required to 144 authenticate and authorize UE and establish mobility session 145 with mobile gateways (SGW/PGW). Functions of the control plane 146 also include system configuration and management. 148 3. Dual Address PDN/PDP Type 150 The dual address Packet Data Network/Packet Data Protocol (PDN/ 151 PDP) Type (IPv4v6) is used in 3GPP context in many cases as a 152 synonym for dual-stack, i.e. a connection type capable of 153 serving both IPv4 and IPv6 simultaneously. 155 4. eNodeB 157 The eNodeB is a base station entity that supports the Long-Term 158 Evolution (LTE) air interface. 160 5. Evolved Packet Core 162 The Evolved Packet Core (EPC) is an evolution of the 3GPP GPRS 163 system characterized by a higher-data-rate, lower-latency, 164 packet-optimized system. The EPC comprises some of the sub 165 components of the EPS core such as Mobility Management Entity 166 (MME), Serving Gateway (SGW), Packet Data Network Gateway (PDN- 167 GW), and Home Subscriber Server (HSS). 169 6. Evolved Packet System 171 The Evolved Packet System (EPS) is an evolution of the 3GPP 172 GPRSsystem characterized by a higher-data-rate, lower-latency, 173 packet-optimized system that supports multiple Radio Access 174 Technologies (RATs). The EPS comprises the EPC together with 175 the Evolved Universal Terrestrial Radio Access (E-UTRA) and the 176 Evolved Universal Terrestrial Radio Access Network (E-UTRAN). 178 7. Evolved UTRAN 180 The Evolved UTRAN (E-UTRAN) is a communications network, 181 sometimes referred to as 4G, and consists of eNodeBs (4G base 182 stations). The E-UTRAN allows connectivity between the User 183 Equipment and the core network. 185 8. GPRS Tunnelling Protocol 187 The GPRS Tunnelling Protocol (GTP) [TS29.060] [TS29.274] 188 [TS29.281] is a tunnelling protocol defined by 3GPP. It is a 189 network-based mobility protocol and is similar to Proxy Mobile 190 IPv6 (PMIPv6). However, GTP also provides functionality beyond 191 mobility, such as in-band signaling related to Quality of 192 Service (QoS) and charging, among others. 194 9. Gateway GPRS Support Node 196 The Gateway GPRS Support Node (GGSN) is a gateway function in 197 the GPRS and 3G network that provides connectivity to the 198 Internet or other PDNs. The host attaches to a GGSN identified 199 by an APN assigned to it by an operator. The GGSN also serves 200 as the topological anchor for addresses/prefixes assigned to the 201 User Equipment. 203 10. General Packet Radio Service 205 The General Packet Radio Service (GPRS) is a packet-oriented 206 mobile data service available to users of the 2G and 3G cellular 207 communication systems -- the GSM -- specified by 3GPP. 209 11. Home Subscriber Server 211 The Home Subscriber Server (HSS) is a database for a given 212 subscriber and was introduced in 3GPP Release-5. It is the 213 entity containing the subscription-related information to 214 support the network entities actually handling calls/sessions. 216 12. Mobility Management Entity 218 The Mobility Management Entity (MME) is a network element that 219 is responsible for control-plane functionalities, including 220 authentication, authorization, bearer management, layer-2 221 mobility, etc. The MME is essentially the control-plane part of 222 the SGSN in the GPRS. The user-plane traffic bypasses the MME. 224 13. Public Land Mobile Network 226 The Public Land Mobile Network (PLMN) is a network that is 227 operated by a single administration. A PLMN (and therefore also 228 an operator) is identified by the Mobile Country Code (MCC) and 229 the Mobile Network Code (MNC). Each (telecommunications) 230 operator providing mobile services has its own PLMN. 232 14. Policy and Charging Control 234 The Policy and Charging Control (PCC) framework is used for QoS 235 policy and charging control. It has two main functions: flow- 236 based charging, including online credit control and policy 237 control (e.g., gating control, QoS control, and QoS signaling). 238 It is optional to 3GPP EPS but needed if dynamic policy and 239 charging control by means of PCC rules based on user and 240 services are desired. 242 15. Packet Data Network 244 The Packet Data Network (PDN) is a packet-based network that 245 either belongs to the operator or is an external network such as 246 the Internet or a corporate intranet. The user eventually 247 accesses services in one or more PDNs. The operator's packet 248 core networks are separated from packet data networks either by 249 GGSNs or PDN Gateways (PGWs). 251 16. Serving Gateway 253 The Serving Gateway (SGW) is a gateway function in the EPS, 254 which terminates the interface towards the E-UTRAN. The SGW is 255 the Mobility Anchor point for layer-2 mobility (inter-eNodeB 256 handovers). For each UE connected with the EPS, at any given 257 point in time, there is only one SGW. The SGW is essentially 258 the user-plane part of the GPRS's SGSN. 260 17. Packet Data Network Gateway 262 The Packet Data Network Gateway (PGW) is a gateway function in 263 the Evolved Packet System (EPS), which provides connectivity to 264 the Internet or other PDNs. The host attaches to a PGW 265 identified by an APN assigned to it by an operator. The PGW 266 also serves as the topological anchor for addresses/prefixes 267 assigned to the User Equipment. 269 18. Packet Data Protocol Context 271 A Packet Data Protocol (PDP) context is the equivalent of a 272 virtual connection between the User Equipment (UE) and a PDN 273 using a specific gateway. 275 19. Packet Data Protocol Type 277 A Packet Data Protocol Type (PDP Type) identifies the used/ 278 allowed protocols within the PDP context. Examples are IPv4, 279 IPv6, and IPv4v6 (dual-stack). 281 20. Serving GPRS Support Node 283 The Serving GPRS Support Node (SGSN) is a network element that 284 is located between the radio access network (RAN) and the 285 gateway (GGSN). A per-UE point-to-point (p2p) tunnel between 286 the GGSN and SGSN transports the packets between the UE and the 287 gateway. 289 21. Terminal Equipment 290 The Terminal Equipment (TE) is any device/host connected to the 291 Mobile Terminal (MT) offering services to the user. A TE may 292 communicate to an MT, for example, over the Point to Point 293 Protocol (PPP). 295 22. UE, MS, MN, and Mobile 297 The terms UE (User Equipment), MS (Mobile Station), MN (Mobile 298 Node), and mobile refer to the devices that are hosts with the 299 ability to obtain Internet connectivity via a 3GPP network. A 300 MS is comprised of the Terminal Equipment (TE) and a Mobile 301 Terminal (MT). The terms UE, MS, MN, and mobile are used 302 interchangeably within this document. 304 23. User Plane 306 The user plane refers to data traffic and the required bearers 307 for the data traffic. In practice, IP is the only data traffic 308 protocol used in the user plane. 310 2. LTE, 4G Mobile Network 312 2.1. Network Overview 314 With the introduction of LTE, mobile networks moved to all-IP 315 transport for all elements such as eNodeB, MME, SGW/PGW, HSS, PCRF, 316 routing and switching etc. Although LTE network is data-centric, it 317 has support for legacy Circuit Switch features like voice and SMS 318 through transitional CS fallback and flexible IMS deployment 319 [GRAYSON]. For each mobile device attached to the radio (eNodeB) 320 there is a separate overlay tunnel (GPRS Tunneling Protocol, GTP) 321 between eNodeB and Mobile gateways (i.e. SGW, PGW). 323 The GTP tunnel is used to carry user traffic between gateways and 324 mobile devices, this forces data to be only distributed using unicast 325 mechanism. It is also important to understand the overhead of a GTP 326 and IPSec protocols because it has impact on the carried user data 327 traffic. All mobile backhaul traffic is encapsulated using GTP 328 tunnel, which has overhead of 8 bytes on top of IP and UDP [NGMN]. 329 Additionally, if IPSec is used for security (which is often required 330 if the Service provider is using a shared backhaul), it adds overhead 331 based upon IPSec tunneling model (tunnel or transport), and 332 encryption and authentication header algorithm used. If we factor 333 Advanced Encryption Standard (AES) encryption with the packet size, 334 the overhead can be significant [OLTEANU], particularly for the 335 smaller payloads. 337 When any UE is powered up, it attaches to a mobile network based on 338 its configuration and subscription. After successful attach 339 procedure, UE registers with the mobile core network and IPv4 and/or 340 IPv6 address is assigned. A default bearer is created for each UE 341 and it is assigned to default Access Point Name (APN). 343 +-------+ Diameter +-------+ 344 | HSS |------------| SPR | 345 +-------+ +-------+ 346 | | 347 +------+ +------+ S4 | +-------+ 348 | 3G |---| SGSN |----------------|------+ +------| PCRF | 349 ^ |NodeB | | |---------+ +---+ | | +-------+ 350 +-+ | +------+ +------+ S3 | | S6a | |Gxc | 351 | | | +-------+ | | |Gx 352 +-+ | +------------------| MME |------+ | | | 353 UE v | S1MME +-------+ S11 | | | | 354 +----+-+ +-------+ +-------+ 355 |4G/LTE|------------------------------| SGW |-----| PGW | 356 |eNodeB| S1U +-------+ +--| | 357 +------+ | +-------+ 358 +---------------------+ | | 359 S1U GTP Tunnel traffic | +-------+ | | 360 S2a GRE Tunnel traffic |S2A | ePDG |-------+ | 361 S2b GRE Tunnel traffic | +-------+ S2B |SGi 362 SGi IP traffic | | | 363 +---------+ +---------+ +-----+ 364 | Trusted | |Untrusted| | CDN | 365 |non-3GPP | |non-3GPP | +-----+ 366 +---------+ +---------+ 367 | | 368 +-+ +-+ 369 | | | | 370 +-+ +-+ 371 UE UE 373 Figure 1: LTE, 4G Mobile Network Overview 375 The data delivered to mobile devices is unicast inside GTP tunnel. 376 If we consider combined impact of GTP, IPSec and unicast traffic, the 377 data delivery is not efficient. IETF has developed various header 378 compression algorithms to reduce the overhead associated with IP 379 packets. Some of techniques are robust header compression (ROHC) and 380 enhanced compression of the real-time transport protocol (ECRTP) so 381 that impact of overhead created by GTP, IPsec etc. is reduced to some 382 extent [BROWER]. For commercial mobile networks, 3GPP has adopted 383 different mechanisms for header compression to achieve efficiency in 384 data delivery [TS25.323], and can be adapted to ICN as well. 386 2.2. QoS Challenges 388 During attach procedure, default bearer is created for each UE and it 389 is assigned to the default Access Point Name (APN). The QoS values 390 uplink and downlink bandwidth assigned during initial attach are 391 minimal. Additional dedicated bearer(s) with enhanced QoS parameters 392 is established depending on the specific application needs. 394 While all traffic within a certain bearer gets the same treatment, 395 QoS parameters supporting these requirements can be very granular in 396 different bearers. These values vary for the control, management and 397 user traffic, and depending on the application key parameters, such 398 as latency, jitter (important for voice and other real-time 399 applications), packet loss and queuing mechanism (strict priority, 400 low-latency, fair etc.) can be very different. 402 Implementation of QoS for mobile networks is done at two stages: at 403 content prioritization/marking and transport marking, and congestion 404 management. From the transport perspective, QoS is defined at layer 405 2 as class of service (CoS) and at layer 3 either as DiffServ code 406 point (DSCP) or type of service (ToS). The mapping of CoS to DSCP 407 takes place at layer 2/3 switching and routing elements. 3GPP has 408 specified QoS Class Identifier (QCI) which represents different types 409 of content and equivalent mapping to DSCP at transport layer 410 [TS23.401]; however, this again requires manual configuration at 411 different elements and if there is misconfiguration at any place in 412 the path it will not work properly. 414 In summary QoS configuration for mobile network for user plane (for 415 user traffic) and transport in IP based mobile network is complex and 416 it requires synchronization of parameters among different platforms. 417 Normally QoS in IP is implemented using DiffServ, which uses hop-by- 418 hop QoS configuration at each router. Any inconsistency in IP QoS 419 configuration at routers in the forwarding path can result in poor 420 subscriber experience (e.g. packet classified as high-priority can go 421 to lower priority queue). By deploying ICN, we intend to enhance the 422 subscriber experience using policy based configuration, which can be 423 associated with the named contents [ICNQoS] at ICN forwarder. 424 Further investigation is needed to understand how QoS in ICN can be 425 implemented to meet the IP QoS requirements [RFC4594]. 427 Research papers published so far explore the possibility of 428 classifications based on name prefixes (thus addressing the problem 429 of IP QoS not being information-aware), or on popularity or placement 430 (basically looking at a distance of a content from a requester). 432 However, a common limitation of these research efforts is that they 433 focus on faster routing of Interest request towards the content 434 rather than the quality of experience based on actual content 435 delivery. For that to happen, QoS should be implemented and enforced 436 on the Data packet path. 438 2.3. Data Transport Using IP 440 The data delivered to mobile devices is unicast inside GTP tunnel 441 from a eNodeB to a PDN gateway (PGW), as described in 3GPP 442 specifications [TS23.401]. While the technology exists to address 443 the issue of possible multicast delivery, there are many difficulties 444 related to multicast protocol implementation on the RAN side of the 445 network. Transport networks in the backhaul and core have addressed 446 the multicast delivery long time ago and have implemented it in most 447 cases in their multi-purpose integrated transport, but the RAN part 448 of the network is still lagging behind due to complexities related to 449 mobility of the clients, handovers, and the fact that the potential 450 gain to the Service Providers may not justify the investment. With 451 that said, the data delivery in the mobility remains greatly unicast. 452 Techniques to handle multicast such as LTE-B or eMBMS have been 453 designed to handle pre-planned content delivery such as live content, 454 which contrasts user behavior today, largely based on content (or 455 video) on demand model. 457 To ease the burden on the bandwidth of the SGi interface, caching is 458 introduced in a similar manner as with many Enterprises. In the 459 mobile networks, whenever possible, a cached data is delivered. 460 Caching servers are placed at a centralized location, typically in 461 the Service Provider's Data Center, or in some cases lightly 462 distributed in the Packet Core locations with the PGW nodes close to 463 the Internet and IP services access (SGi interface). This is a very 464 inefficient concept because traffic has to traverse the entire 465 backhaul path for the data to be delivered to the end-user. Other 466 issues, such as out-of-order delivery contribute to this complexity 467 and inefficiency but they could be addressed at the IP transport 468 level. 470 The data delivered to mobile devices is unicast inside a GTP tunnel. 471 If we consider combined impact of GTP, IPSec and unicast traffic, the 472 end-to-end data delivery is not efficient. By deploying ICN, we 473 intend to either terminate GTP tunnel at the mobility anchoring point 474 by leveraging control and user plane separation or replace it with 475 the native ICN protocols. 477 2.4. Virtualizing Mobile Networks 479 The Mobile packet core deployed in a major service provider network 480 is either based on dedicated hardware or large capacity x86 platforms 481 in some cases. With adoption of Mobile Virtual Network Operators 482 (MVNO), public safety network, and enterprise mobility network, we 483 need elastic mobile core architecture. By deploying mobile packet 484 core on a commercially off the shelf (COTS) platform using 485 virtualized infrastructure (NFVI) framework and end-to-end 486 orchestration, we can simplify new deployments and provide optimized 487 total cost of ownership (TCO). 489 While virtualization is growing and many mobile providers use hybrid 490 architecture consisting of dedicated and virtualized infrastructures, 491 the control and data delivery planes are still the same. There is 492 also work underway to separate control plane and user plane so that 493 the network can scale better. Virtualized mobile networks and 494 network slicing with control and user plane separation provide 495 mechanism to evolve GTP-based architecture to open-flow SDN-based 496 signaling for LTE and proposed 5G core. Some of early architecture 497 work for 5G mobile technologies provides mechanism for control and 498 user plane separation and simplifies mobility call flow by 499 introduction of open- flow based signaling [ICN5G]. This has been 500 considered by 3GPP [EPCCUPS] and is also described in [SDN5G]. 502 3. Data Transport Using ICN 504 For mobile devices, the edge connectivity to the network is between 505 radio and a router or mobile edge computing (MEC) [MECSPEC] element. 506 MEC has the capability of processing client requests and segregating 507 control and user traffic at the edge of radio rather than sending all 508 requests to the mobile gateway. 510 +----------+ 511 | Content +----------------------------------------+ 512 | Publisher| | 513 +---+---+--+ | 514 | | +--+ +--+ +--+ | 515 | +--->|R1|------------>|R2|---------->|R4| | 516 | +--+ +--+ +--+ | 517 | | Cached | 518 | v content | 519 | +--+ at R3 | 520 | +========|R3|---+ | 521 | # +--+ | | 522 | # | | 523 | v v | 524 | +-+ +-+ | 525 +---------------| |-------------| |-------------+ 526 +-+ +-+ 527 Consumer-1 Consumer-2 528 UE UE 530 ===> Content flow from cache 531 ---> Content flow from publisher 533 Figure 2: ICN Architecture 535 MEC transforms radio into an intelligent service edge that is capable 536 of delivering services directly from the edge of the network, while 537 providing the best possible performance to the client. MEC can be an 538 ideal candidate for ICN forwarder in addition to its usual function 539 of managing mobile termination. In addition to MEC, other transport 540 elements, such as routers, can work as ICN forwarders. 542 Data transport using ICN is different compared to IP-based transport. 543 It evolves the Internet infrastructure by introducing uniquely named 544 data as a core Internet principle. Communication in ICN takes place 545 between content provider (producer) and end user (consumer) as 546 described in Figure 2. 548 Every node in a physical path between a client and a content provider 549 is called ICN forwarder or router, and it has the ability to route 550 the request intelligently and also cache the content so that it can 551 be delivered locally for subsequent request from any other client. 552 For mobile network, transport between a client and a content provider 553 consists of radio network + mobile backhaul and IP core transport + 554 Mobile Gateways + Internet + content data network (CDN). 556 In order to understand suitability of ICN for mobile networks, we 557 will discuss the ICN framework describing protocols architecture and 558 different types of messages, and then consider how we can use this in 559 a mobile network for delivering content more efficiently. ICN uses 560 two types of packets called "interest packet" and "data packet" as 561 described in Figure 3. 563 +------------------------------------+ 564 Interest | +------+ +------+ +------+ | +-----+ 565 +-+ ---->| CS |---->| PIT |---->| FIB |--------->| CDN | 566 | | | +------+ +------+ +------+ | +-----+ 567 +-+ | | Add | Drop | | Forward 568 UE <--------+ Intf v Nack v | 569 Data | | 570 +------------------------------------+ 572 +------------------------------------+ 573 +-+ | Forward +------+ | +-----+ 574 | | <-------------------------------------| PIT |<---------| CDN | 575 +-+ | | Cache +--+---+ | Data +-----+ 576 UE | +--v---+ | | 577 | | CS | v | 578 | +------+ Discard | 579 +------------------------------------+ 581 Figure 3: ICN Interest, Data Packet and Forwarder 583 In an LTE network, when a mobile device wants to get certain content, 584 it will send an Interest message to the closest eNodeB. Interest 585 packet follows the TLV format [CCNxTLV] and contains mandatory fields 586 such as name of the content and content matching restrictions 587 (KeyIdRestr and ContentObjectHashRestr) forming the tuple [CCNxSem]. 588 The content matching tuple uniquely identifies the correlation 589 between an Interest and data packet. Another attribute called 590 HopLimit is used to detect looping Interest messages. Interest 591 looping is not prevented and looped Interest packets are eventually 592 discarded at the expiry of HopLimit. 594 First ICN router will receive Interest packet and perform lookup if 595 request for such content has come earlier from any other client. If 596 yes, it is served from the local cache, otherwise request is 597 forwarded to the next-hop ICN router. Each ICN router maintains 598 three data structures, namely Pending Interest Table (PIT), 599 Forwarding Information Base (FIB), and Content Store (CS). The 600 Interest packet travels hop-by-hop towards content provider. Once 601 the Interest reaches the content provider it will return a Data 602 packet containing information such as content name, signature, signed 603 key and data. 605 Data packet travels in reverse direction following the same path 606 taken by the interest packet so routing symmetry is maintained. 607 Details about algorithms used in PIT, FIB, CS and security trust 608 models are described in various resources [CCN], here we explained 609 the concept and its applicability to the LTE network. 611 4. ICN Deployment in 4G and LTE Networks 613 4.1. General ICN Deployment Considerations 615 In LTE/4G mobile networks, both user and control plane traffic have 616 to be transported from the edge to the mobile packet core via IP 617 transport. The evolution of existing mobile packet core using CUPS 618 [TS23.714] enables flexible network deployment and operation, by 619 distributed deployment and the independent scaling between control 620 plane and user plane functions - while not affecting the 621 functionality of the existing nodes subject to this split. 623 In the CUPS architecture, there is an opportunity to shorten the path 624 for user plane traffic by deploying offload nodes closer to the edge 625 [OFFLOAD]. With this major architecture change, User Plane Function 626 (UPF) node is placed close to the edge so traffic no longer needs to 627 traverse the entire backhaul path to reach the EPC. In many cases, 628 where feasible, UPF can be collocated with the eNodeB, which is also 629 a business decision based on the user demand. Placing a Publisher 630 close to the offload site, or at the offload site, provides for a 631 significant improvement in user experience, especially with the 632 latency-sensitive applications. This optimization allows for the 633 introduction of ICN and amplifies its advantages. This section 634 analyzes the potential impact of ICN on control and user plane 635 traffic for centralized and disaggregate CUPS based mobile network 636 architecture. 638 4.2. ICN Deployment Scenarios 640 Deployment of ICN provides an opportunity to further optimize the 641 existing data transport in LTE/4G mobile networks. The various 642 deployment options that ICN and IP provide are somewhat analogous to 643 the deployment scenarios when IPv6 was introduced to inter operate 644 with IPv4, except with ICN the whole IP stack is being replaced. We 645 have reviewed [RFC6459] and analyzed the impact of ICN on control 646 plane signaling and user plane data delivery. In general ICN can be 647 deployed natively replacing IP transport (IPv4 and IPv6) or as an 648 overlay protocol. Figure 4 describes a modified protocol stack to 649 support ICN deployment scenarios. 651 +----------------+ +-----------------+ 652 | ICN App (new) | |IP App (existing)| 653 +---------+------+ +-------+---------+ 654 | | 655 +---------+----------------+---------+ 656 | Transport Convergence Layer (new) | 657 +------+---------------------+-------+ 658 | | 659 +------+------+ +------+-------+ 660 |ICN function | | IP function | 661 | (New) | | (Existing) | 662 +------+------+ +------+-------+ 663 | | 664 (```). (```). 665 ( ICN '`. ( IP '`. 666 ( Cloud ) ( Cloud ) 667 ` __..'+' ` __..'+' 669 Figure 4: IP/ICN Convergence and Deployment Scenarios 671 As shown in Figure 4, for applications running either in UE or in 672 content provider system to use the new transport option, we propose a 673 new transport convergence layer (TCL). This transport convergence 674 layer helps determine what type of transport (e.g. ICN or IP), as 675 well as type of radio interface (e.g. LTE or WiFi or both), is used 676 to send and receive the traffic based on preference e.g. content 677 location, content type, content publisher, congestion, cost, quality 678 of service etc. It helps to configure and decide the type of 679 connection as well as the overlay mode (ICNoIP or IPoICN) between 680 application and the protocol stack (IP or ICN) to be used. 682 The ICN function together with existing IP function provides the 683 support for either native ICN and/or the dual stack (ICN/IP) 684 transport functionality. More elaborate description on these 685 functional layers is provided in Section 4.4.1. 687 TCL can use a number of mechanisms for the selection of transport. 688 It can use a per application configuration through a management 689 interface, possibly even a user-facing setting realized through a 690 user interface, similar to those used today that select cellular over 691 WiFi being used for selected applications. In another option, it 692 might use a software API, which an adapted IP application could use 693 to specify e.g. an ICN transport for obtaining its benefits. 695 Another potential application of TCL is in implementation of network 696 slicing, where it can have a slice management capability locally or 697 it can interface to an external slice manager through an API [GALIS]. 698 This solution can enable network slicing for IP and ICN transport 699 selection from the UE itself. The TCL could apply slice settings to 700 direct certain traffic (or applications) over one slice and others 701 over another slice, determined by some form of 'slicing policy'. 702 Slicing policy can be obtained externally from slice manager or 703 configured locally on UE. 705 From the perspective of the applications either on UE or content 706 provider, following options are possible for the deployment of ICN 707 natively and/or with IP. 709 1. IP over IP 711 In this scenario UE uses applications tightly integrated with the 712 existing IP transport infrastructure. In this option, the TCL 713 has no additional function since the packets are directly 714 forwarded using IP protocol stack, which in turn sends the 715 packets over the IP transport. 717 2. ICN over ICN 719 Similar to case 1 above, ICN applications tightly integrate with 720 the ICN transport infrastructure. The TCL has no additional 721 responsibility since the packets are directly forwarded using ICN 722 protocol stack, which in turn sends the packets over the ICN 723 transport. 725 3. ICN over IP (ICNoIP) 727 In ICN over IP scenario, the underlying IP transport 728 infrastructure is not impacted (i.e. ICN is implemented, as an 729 IP overlay, between user equipment (UE) and content provider). 730 IP routing is used from Radio Access Network (eNodeB) to mobile 731 backhaul, IP core and Mobile Gateway (SGW/PGW). UE attaches to 732 Mobile Gateway (SGW/PGW) using IP address. Also, the data 733 transport between Mobile Gateway (SGW/PGW) and content publisher 734 uses IP. Content provider is capable of serving content either 735 using IP or ICN, based on UE request. 737 An alternative approach to implement ICN over IP is provided in 738 Hybrid ICN [HICN], which implements ICN over IP by mapping of ICN 739 names to the IPv4/IPv6 addresses. 741 Detailed deployment of use cases is described in section 4.4. 742 Application conveys the preference to the TCL, which in turn 743 sends the ICN data packets using the IP transport. 745 4. IP over ICN (IPoICN) 747 H2020 project [H2020] provides an architectural framework for 748 deployment of IP as an overlay over ICN protocol [IPoICN]. 749 Implementing IP services over ICN provides an opportunity 750 leveraging benefit of ICN in the transport infrastructure and 751 there is no impact on end devices (UE and access network) as they 752 continue to use IP. IPoICN however, will require an inter- 753 working function (IWF/Border Gateway) to translate various 754 transport primitives such as transport of tunnel mode. IWF 755 function will provide a mechanism for protocol translation 756 between IPoICN and native IP deployment for mobile network. 757 After reviewing [IPoICN], we understand and interpret that ICN is 758 implemented in the transport natively; however, IP is implemented 759 in UE, eNodeB, and Mobile gateway (SGW/PGW), which is also called 760 as network attach point (NAP). 762 4.3. ICN Deployment in LTE Control Plane 764 In this section we analyze signaling messages which are required for 765 different procedures, such as attach, handover, tracking area update 766 etc. The goal of analysis is to see if there is any benefit to 767 replace IP-based protocols with ICN for LTE signaling in the current 768 architecture. It is important to understand the concept of point of 769 attachment (POA). When UE connects to a network it has following 770 POAs: 772 1. eNodeb managing location or physical POA 774 2. Authentication and Authorization (MME, HSS) managing identity or 775 authentication POA 777 3. Mobile Gateways (SGW, PGW) managing logical or session management 778 POA 780 In current architecture IP transport is used for all the messages 781 associated with Control Plane for mobility and session management. 782 IP is embedded very deeply into these messages and TLV carrying 783 additional attributes as a layer 3 transport . Physical POA in eNodeB 784 handles both mobility and session management for any UE attached to 785 4G, LTE network. The number of mobility management messages between 786 different nodes in an LTE network per signaling procedure are shown 787 in Table 1. 789 Normally two types of UE devices attach to LTE network: SIM based 790 (need 3GPP mobility protocol for authentication) or non-SIM based 791 (which connect to WiFi network), and authentication is required for 792 both of these device types. For non-SIM based devices, AAA is used 793 for authentication. We do not propose to change UE authentication or 794 mobility management messaging for user data transport using ICN. A 795 separate study would be required to analyze impact of ICN on mobility 796 management messages structures and flows. We are merely analyzing 797 the viability of implementing ICN as a transport for Control plane 798 messages. 800 It is important to note that even if MME and HSS do not support ICN 801 transport, they still need to support UE capable of dual stack or 802 native ICN. When UE initiates attach request using the identity as 803 ICN, MME must be able to parse that message and create a session. 804 MME forwards UE authentication to HSS so HSS must be able to 805 authenticate an ICN capable UE and authorize create session 806 [TS23.401]. 808 +---------------------------+-----+-----+-----+-----+------+ 809 | LTE Signaling Procedures | MME | HSS | SGW | PGW | PCRF | 810 +---------------------------+-----+-----+-----+-----+------+ 811 | Attach | 10 | 2 | 3 | 2 | 1 | 812 | Additional default bearer | 4 | 0 | 3 | 2 | 1 | 813 | Dedicated bearer | 2 | 0 | 2 | 2 | 0 | 814 | Idle-to-connect | 3 | 0 | 1 | 0 | 0 | 815 | Connect-to-Idle | 3 | 0 | 1 | 0 | 0 | 816 | X2 handover | 2 | 0 | 1 | 0 | 0 | 817 | S1 handover | 8 | 0 | 3 | 0 | 0 | 818 | Tracking area update | 2 | 2 | 0 | 0 | 0 | 819 | Total | 34 | 2 | 14 | 6 | 3 | 820 +---------------------------+-----+-----+-----+-----+------+ 822 Table 1: Signaling Messages in LTE Gateways 824 Anchorless mobility [ALM] has made some important comments on how 825 mobility management is done in ICN. Author comments about handling 826 mobility without having a dependency on the core network function 827 e.g. MME. However, location update to the core network would still 828 be required to support some of the legal compliance requirements such 829 as lawful intercept and emergency services. 831 The main advantage of ICN is in caching and reusing the content, 832 which does not apply to the transactional signaling exchange. After 833 analyzing LTE signaling call flows [TS23.401] and messages inter- 834 dependencies Table 1, our recommendation is that it is not beneficial 835 to deploy ICN for control plane and mobility management functions. 837 4.4. ICN Deployment in LTE User Plane 839 We will consider Figure 1 to discuss different mechanisms to deploy 840 ICN in mobile networks. In section 4.2 we discussed generi 841 deployment scenarios of ICN. In this section, we shall see the 842 specific use cases of native ICN deployment in LTE user plane. We 843 consider the following options: 845 1. Dual stack ICN deployment in UE 847 2. Native ICN Deployments in UE 849 3. ICN Deployment in eNodeB 851 4. ICN Deployment in mobile gateways (SGW/PGW) 853 4.4.1. Dual stack ICN Deployments in UE 855 The control and user plane communications in LTE, 4G mobile networks 856 are specified in 3GPP documents [TS23.203] and [TS23.401]. It is 857 important to understand that UE can be either consumer (receiving 858 content) or publisher (pushing content for other clients). The 859 protocol stack inside mobile device (UE) is complex as it has to 860 support multiple radio connectivity access to eNodeB(s). 862 Figure 5 provides high level description of a protocol stack, where 863 IP is defined at two layers: (1) at user plane communication, (2) 864 Transport layer. User plane communication takes place between Packet 865 Data Convergence Protocol (PDCP) and Application layer, whereas 866 transport layer is at GTP protocol stack. 868 The protocol interactions and impact of supporting tunneling of ICN 869 packet into IP or to support ICN natively are described in Figure 5 870 and Figure 6 respectively. 872 +--------+ +--------+ 873 | App | | CDN | 874 +--------+ +--------+ 875 |Transp. | | | | |Transp. | 876 |Converg.|.|..............|...............|............|.|Converge| 877 +--------+ | | | +--------+ | +--------+ 878 | |.|..............|...............|.| |.|.| | 879 | ICN/IP | | | | | ICN/IP | | | ICN/IP| 880 | | | | | | | | | | 881 +--------+ | +----+-----+ | +-----+-----+ | +-----+--+ | +--------+ 882 | |.|.| | |.|.| | |.|.| | | | | | 883 | PDCP | | |PDCP|GTP-U| | |GTP-U|GTP-U| | |GTP-U| | | | L2 | 884 +--------+ | +----------+ | +-----------+ | +-----+ | | | | 885 | RLC |.|.|RLC | UDP |.|.| UDP | UDP |.|.|UDP |L2|.|.| | 886 +--------+ | +----------+ | +-----------+ | +-----+ | | | | 887 | MAC |.|.| MAC| L2 |.|.| L2 | L2 |.|.| L2 | | | | | 888 +--------+ | +----------+ | +-----------+ | +--------+ | +--------+ 889 | L1 |.|.| L1 | L1 |.|.| L1 | L1 |.|.| L1 |L1|.|.| L1 | 890 +--------+ | +----+-----+ | +-----+-----+ | +-----+--+ | +--------+ 891 UE | BS(enodeB) | SGW | PGW | 892 Uu S1U S5/S8 SGi 894 Figure 5: Dual stack ICN Deployment in UE 896 The protocols and software stack used inside LTE capable UE support 897 both 3G and LTE software interworking and handover. Latest 3GPP 898 Rel.13 onward specification describes the use of IP and non-IP 899 protocols to establish logical/session connectivity. We intend to 900 leverage the non-IP protocol based mechanism to deploy ICN protocol 901 stack in UE as well as in eNodeB and mobile gateways (SGW, PGW). 903 1. Existing application layer can be modified to provide options for 904 new ICN based application and existing IP based applications. UE 905 can continue to support existing IP based applications or host 906 new applications developed either to support native ICN as 907 transport, ICNoIP or IPoICN based transport. Application layer 908 has the option of selecting either ICN or IP transport layer as 909 well as radio interface to send and receive data traffic. 911 Our proposal is to provide a common Application Programming 912 Interface (API) to the application developers such that there is 913 no impact on the application development when they choose either 914 ICN or IP transport for exchanging the traffic with the network. 915 As mentioned in section 4.2, the transport convergence layer 916 (TCL) function handles the interaction of application with the 917 multiple transport options. 919 2. The transport convergence layer helps determine what type of 920 transport (e.g. ICN or IP) as well as type of radio interface 921 (e.g. LTE or WiFi or both), is used to send and receive the 922 traffic. Application layer can make the decision to select a 923 specific transport based on preference e.g. content location, 924 content type, content publisher, congestion, cost, quality of 925 service etc. There can be an Application Programming Interface 926 (API) to exchange parameters required for transport selection. 927 The southbound interactions of Transport Convergence Layer (TCL) 928 will be either to IP or ICN at the network layer. 930 +----------------+ +-----------------+ 931 | ICN App (new) | |IP App (existing)| 932 +---------+------+ +-------+---------+ 933 | | 934 +---------+----------------+---------+ 935 | Transport Convergence Layer (new) | 936 +------+---------------------+-------+ 937 | | 938 +------+------+ +------+-------+ 939 |ICN function | | IP function | 940 | (New) | | (Existing) | 941 +------+------+ +------+-------+ 942 | | 943 +------+---------------------+-------+ 944 | PDCP (updated to support ICN) | 945 +-----------------+------------------+ 946 | 947 +-----------------+------------------+ 948 | RLC (Existing) | 949 +-----------------+------------------+ 950 | 951 +-----------------+------------------+ 952 | MAC Layer (Existing) | 953 +-----------------+------------------+ 954 | 955 +-----------------+------------------+ 956 | Physical L1 (Existing) | 957 +------------------------------------+ 959 Figure 6: Dual stack ICN protocol interactions 961 3. ICN function (forwarder) is introduced in parallel to the 962 existing IP layer. ICN forwarder contains functional 963 capabilities to forward ICN packets, e.g. Interest packet to 964 eNodeB or response "data packet" from eNodeB to the application. 966 4. For dual stack scenario, when UE is not supporting ICN at 967 transport layer, we use IP underlay to transport ICN packets. 968 ICN function will use IP interface to send Interest and Data 969 packets for fetching or sending data using ICN protocol function. 970 This interface will use ICN overlay over IP using any overlay 971 tunneling mechanism. 973 5. To support ICN at network layer in UE, PDCP layer has to be aware 974 of ICN capabilities and parameters. PDCP is located in the Radio 975 Protocol Stack in the LTE Air interface, between IP (Network 976 layer) and Radio Link Control Layer (RLC). PDCP performs 977 following functions [TS36.323]: 979 1. Data transport by listening to upper layer, formatting and 980 pushing down to Radio Link Layer (RLC) 982 2. Header compression and decompression using ROHC (Robust 983 Header Compression) 985 3. Security protections such as ciphering, deciphering and 986 integrity protection 988 4. Radio layer messages associated with sequencing, packet drop 989 detection and re-transmission etc. 991 6. No changes are required for lower layer such as RLC, MAC and 992 Physical (L1) because they are not IP aware. 994 One key point to understand in this scenario is that ICN is deployed 995 as an overlay on top of IP. 997 4.4.2. Native ICN Deployments in UE 999 We propose to implement ICN natively in UE by modifying PDCP layer in 1000 3GPP protocols. Figure 7 provides a high-level protocol stack 1001 description where ICN is used at following different layers: 1003 1. at user plane communication 1005 2. at transport layer 1007 User plane communication takes place between PDCP and application 1008 layer, whereas transport layer is a substitute of GTP protocol. 1009 Removal of GTP protocol stack is significant change in mobile 1010 architecture because GTP is used not just for routing but for 1011 mobility management functions such as billing, mediation, policy 1012 enforcement etc. 1014 If we implement ICN natively in UE, communication between UE and 1015 eNodeB will change. Also, this will avoid tunneling the user plane 1016 traffic from eNodeB to mobile packet core (SGW, PGW) using GTP 1017 tunnel. 1019 For native ICN deployment, an application will be configured to use 1020 ICN forwarder so there is no need for Transport Convergence. Also to 1021 support ICN at network layer in UE, we need to modify existing PDCP 1022 layer. PDCP layer has to be aware of ICN capabilities and 1023 parameters. 1025 Native implementation will also provide opportunities to develop new 1026 use cases leveraging ICN capabilities such as seamless mobility, UE 1027 to UE content delivery using radio network without traversing the 1028 mobile gateways, etc. 1030 +--------+ +--------+ 1031 | App | | CDN | 1032 +--------+ +--------+ 1033 |Transp. | | | | | |Transp. | 1034 |Converge|.|..............|..............|..............|.|Converge| 1035 +--------+ | | | | +--------+ 1036 | |.|..............|..............|..............|.| | 1037 | ICN/IP | | | | | | | 1038 | | | | | | | | 1039 +--------+ | +----+-----+ | +----------+ | +----------+ | | ICN/IP | 1040 | |.|.| | | | | | | | | | | | 1041 | PDCP | | |PDCP| ICN |.|.| ICN |.|.| ICN |.|.| | 1042 +--------+ | +----+ | | | | | | | | | | 1043 | RLC |.|.|RLC | | | | | | | | | | | 1044 +--------+ | +----------+ | +----------+ | +----------+ | +--------+ 1045 | MAC |.|.| MAC| L2 |.|.| L2 |.|.| L2 |.|.| L2 | 1046 +--------+ | +----------+ | +----------+ | +----------+ | +--------+ 1047 | L1 |.|.| L1 | L1 |.|.| L1 |.|.| L1 |.|.| L1 | 1048 +--------+ | +----+-----+ | +----------+ | +----------+ | +--------+ 1049 UE | BS(enodeB) | SGW | PGW | 1050 Uu S1u S5/S8 SGi 1052 Figure 7: Native ICN Deployment in UE 1054 4.5. ICN Deployment in eNodeB 1056 eNodeB is physical point of attachment for UE, where radio protocols 1057 are converted into IP transport protocol as depicted in Figure 6 and 1058 Figure 7 for dual stack/overlay and native ICN respectively. When UE 1059 performs attach procedures, it is assigned an identity either as IP, 1060 dual stack (IP and ICN), or ICN. UE can initiate data traffic using 1061 any of the follwing options: 1063 1. Native IP (IPv4 or IPv6) 1065 2. Native ICN 1067 3. Dual stack IP (IPv4/IPv6) or ICN 1069 UE encapsulates user data transport request into PDCP layer and sends 1070 the information on air interface to eNodeB. eNodeB receives the 1071 information and using PDCP [TS36.323], de-encapsulates air-interface 1072 messages and converts them to forward to core mobile gateways (SGW, 1073 PGW). As shown in Figure 8, in order to support ICN natively in 1074 eNodeB, it is proposed to provide transport convergence layer (TCL) 1075 capabilities in eNodeB (similar to as provided in UE), which provides 1076 following functions: 1078 1. It decides the forwarding strategy for user data request coming 1079 from UE. The strategy can make decision based on preference 1080 indicated by the application such as congestion, cost, quality of 1081 service, etc. 1083 2. eNodeB to provide open Application Programming Interface (API) to 1084 external management systems, to provide capability to eNodeB to 1085 program the forwarding strategies. 1087 +---------------+ | 1088 | UE request | | ICN +---------+ 1089 +---> | content using |--+--- transport -->| | 1090 | |ICN protocol | | | | 1091 | +---------------+ | | | 1092 | | | | 1093 | +---------------+ | | | 1094 +-+ | | UE request | | IP |To mobile| 1095 | |---+---> | content using |--+--- transport -->| GW | 1096 +-+ | | IP protocol | | |(SGW,PGW)| 1097 UE | +---------------+ | | | 1098 | | | | 1099 | +---------------+ | | | 1100 | | UE request | | Dual stack | | 1101 +---> | content using |--+--- IP+ICN -->| | 1102 |IP/ICN protocol| | transport +---------+ 1103 +---------------+ | 1104 eNodeB S1u 1106 Figure 8: Native ICN Deployment in eNodeB 1108 3. eNodeB shall be upgraded to support three different types of 1109 transport: IP, ICN, and dual stack IP+ICN towards mobile 1110 gateways, as depicted in Figure 8. It is also recommended to 1111 deploy IP and/or ICN forwarding capabilities into eNodeB for 1112 efficient transfer of data between eNodeB and mobile gateways. 1113 There are following choices for forwarding data request towards 1114 mobile gateways: 1116 1. Assuming eNodeB is IP-enabled and UE requests IP transfer, 1117 eNodeB forwards data over IP. 1119 2. Assuming eNodeB is ICN-enabled and UE requests ICN transfer, 1120 eNodeB forwards data over ICN. 1122 3. Assuming eNodeB is IP-enabled and UE requests ICN, eNodeB 1123 overlays ICN on IP and forwards the user plane traffic over 1124 IP. 1126 4. Assuming eNodeB is ICN-enabled and UE requests IP, eNodeB 1127 overlays IP on ICN and forwards the user plane traffic over 1128 ICN [IPoICN]. 1130 4.6. ICN Deployment in Packet Core (SGW, PGW) Gateways 1132 Mobile gateways a.k.a. Evolved Packet Core (EPC) include SGW, PGW, 1133 which perform session management for UE from the initial attach to 1134 disconnection. When UE is powered on, it performs NAS signaling and 1135 after successful authentication it attaches to PGW. PGW is an 1136 anchoring point for UE and responsible for service creations, 1137 authorization, maintenance etc. Entire functionality is managed 1138 using IP address(es) for UE. 1140 In order to implement ICN in EPC, the following functions are needed. 1142 1. Insert ICN function at session management layer as additional 1143 functionality with IP stack. Session management layer is used 1144 for performing attach procedures and assigning logical identity 1145 to user. After successful authentication by HSS, MME sends 1146 create session request (CSR) to SGW and SGW to PGW. 1148 2. When MME sends Create Session Request message (step 12 in 1149 [TS23.401]) to SGW or PGW, it contains Protocol Configuration 1150 Option Information Element (PCO IE) containing UE capabilities. 1151 We can use PCO IE to carry ICN related capabilities information 1152 from UE to PGW. This information is received from UE during the 1153 initial attach request in MME. Details of available TLV, which 1154 can be used for ICN are given in subsequent sections. UE can 1155 support either native IP, or ICN+IP, or native ICN. IP is 1156 referred to as both IPv4 and IPv6 protocols. 1158 3. For ICN+IP capable UE, PGW assigns the UE both IP address and ICN 1159 identity. UE selects either of the identities during the initial 1160 attach procedures and registers with network for session 1161 management. For ICN-capable UE it will provide only ICN 1162 attachment. For native IP-capable UE there is no change. 1164 4. In order to support ICN-capable attach procedures and use ICN for 1165 user plane traffic, PGW needs to have full ICN protocol stack 1166 functionalities. Typical ICN capabilities include functions such 1167 as content store (CS), Pending Interest Table (PIT), Forwarding 1168 Information Base (FIB) capabilities etc. If UE requests ICN in 1169 PCO IE, then PGW registers UE with ICN names. For ICN 1170 forwarding, PGW caches content locally using CS functionality. 1172 5. Protocol configuration options information elements described in 1173 [TS24.008] (see Figure 10.5.136 on page 598) and [TS24.008] (see 1174 Table 10.5.154 on page 599) provide details for different fields. 1176 1. Octet 3 (configuration protocols defines PDN types) which 1177 contains details about IPv4, IPv6, both or ICN. 1179 2. Any combination of Octet 4 to Z can be used to provide 1180 additional information related to ICN capability. It is most 1181 important that PCO IE parameters are matched between UE and 1182 mobile gateways (SGW, PGW) so that they can be interpreted 1183 properly and UE can attach successfully. 1185 6. Deployment of ICN functionalities in SGW and PGW should be 1186 matched with UE and eNodeB because they will exchange ICN 1187 protocols and parameters. 1189 7. Mobile gateways SGW, PGW will also need ICN forwarding and 1190 caching capability. This is especially important if CUPS is 1191 implemented. User Plane Function (UPF), comprising the SGW and 1192 PGW user plane, will be located at the edge of the network and 1193 close to the end-user. ICN-enabled gateway means that this UPF 1194 would serve as a forwarder and should be capable of caching, as 1195 is the case with any other ICN-enabled node. 1197 8. The transport between PGW and CDN provider can be either IP or 1198 ICN. When UE is attached to PGW with ICN identity and 1199 communicates with an ICN-enabled CDN provider, it will use ICN 1200 primitives to fetch the data. On other hand, for an UE attached 1201 with an ICN identity, if PGW has to communicate with an IP- 1202 enabled CDN provider, it will have to use an ICN-IP interworking 1203 gateway to perform conversion between ICN and IP primitives for 1204 data retrieval. In the case of CUPS implementation with an 1205 offload close to the edge, this interworking gateway can be 1206 collocated with the UPF at the offload site to maximize the path 1207 optimization. Further study is required to understand how this 1208 ICN to IP (and vice versa) interworking gateway would function. 1210 4.7. Lab Testing 1212 To further test the modifications proposed above in different 1213 scenarios, a simple lab has been set up as shown in Figure 9. 1215 +------------------------------------------+ 1216 | +-----+ +------+ (```). +------+ | (````). +-----+ 1217 | | SUB |-->| EMU |--(x-haul'.-->| EPC |--->( PDN ).-->| CDN | 1218 | +-----+ +------+ `__..'' +------+ | `__...' +-----+ 1219 +------------------------------------------+ 1221 Figure 9: Native ICN deployment lab setup 1223 The following test scenarios can be set up with VM-based deployment: 1225 1. SUB: ICN simulated client (using ndnSIM), a client application on 1226 workstation requesting content. 1228 2. EMU: test unit emulating eNodeB and UE. This will be a test node 1229 allowing for UE attachment and routing the traffic subsequently 1230 from the Subscriber to the Publisher. 1232 3. EPC: Cisco evolved Packet Core in a single instance (vPC-SI). 1234 4. CDN: content delivery by a Publisher server. 1236 For the purpose of this testing, ICN emulating code (when available) 1237 can be inserted in the test code in EMU to emulate ICN-capable UE 1238 and/or eNodeB. An example of the code to be used is NS3 in its LTE 1239 model. Effect of such traffic on EPC and CDN can be observed and 1240 documented. In a subsequent phase, EPC code supporting ICN can be 1241 tested when available. 1243 Another option is to simulate the UE/eNodeB and EPC functions using 1244 NS3's LTE model [NS3LTE] and EPC model [NS3EPC] respectively. LTE 1245 model includes the LTE Radio Protocol stack, which resides entirely 1246 within the UE and the eNB nodes. This capability shall provide the 1247 for simulation of the UE and eNodeB deployment use cases. Similarly, 1248 EPC model includes core network interfaces, protocols and entities, 1249 which resides within the SGW, PGW and MME nodes, and partially within 1250 the eNB nodes. 1252 Even with its current limitations (i.e. IPv4 only, lack of 1253 integration with ndnSIM, no support for UE idle state etc.) LTE 1254 simulation may be a very useful tool. In any case, both control and 1255 user plane traffic should be tested independently according to the 1256 deployment model discussed in sections 4.4 through 4.6. 1258 5. Security Considerations 1260 To ensure only authenticated UEs are connected to the network, LTE 1261 mobile network implements various security mechanisms. From 1262 perspective of ICN deployment in user plane, it needs to take care of 1263 the following security aspects: 1265 1. UE authentication and authorization 1267 2. Radio or air interface security 1269 3. Denial of service attacks on mobile gateway, services 1271 4. Content positioning either in transport or servers 1273 5. Content cache pollution attacks 1275 6. Secure naming, routing, and forwarding 1277 7. Application security 1279 Security over the LTE air interface is provided through cryptographic 1280 technique. When UE is powered up, it performs key exchange between 1281 UE's USIM and HSS/Authentication Center using NAS messages including 1282 ciphering and integrity protections between UE and MME. Details of 1283 secure UE authentication, key exchange, ciphering and integrity 1284 protections messages are given in 3GPP call flow [TS23.401]. 1286 LTE is an all-IP network and uses IP transport in its mobile backhaul 1287 (e.g. between eNodeB and core network). In case of provider owned 1288 backhaul, it may not implement security mechanisms; however, they are 1289 necessary in case it uses shared or a leased network. The native IP 1290 transport continues to leverage security mechanism such as Internet 1291 key exchange (IKE) and the IP security protocol (IPsec). More 1292 details of mobile backhaul security are provided in 3GPP network 1293 security [TS33.310] and [TS33.320]. When mobile backhaul is upgraded 1294 to support dual stack (IP+ICN) or native ICN, it is required to 1295 implement security techniques which are deployed in mobile backhaul. 1297 When ICN forwarding is enabled on mobile transport routers, we need 1298 to deploy security practices based on [RFC7476] and [RFC7927]. 1300 Some of the key functions supported by LTE mobile gateway (SGW, PGW) 1301 are content based billing, deep packet inspection (DPI), and lawful 1302 intercept (LI). For ICN-based user plane traffic, it is required to 1303 integrate ICN security for session between UE and gateway; however, 1304 in ICN network, since only consumers who are in possession of 1305 decryption keys can access the content, some of the services provided 1306 by mobile gateways mentioned above may not work. Further research in 1307 this area is needed. 1309 6. Summary 1311 In this draft, we have discussed complexities of LTE network and key 1312 dependencies for deploying ICN in user plane data transport. 1313 Different deployment options described cover aspects such as inter- 1314 operability and multi-technology, which is a reality for any service 1315 provider. We are currently evaluating the ICN deployment options, 1316 described in section 4, using LTE gateway software and ICN simulator. 1317 One can deploy ICN for data transport in user plane either as an 1318 overlay, dual stack (IP + ICN) or natively (by integrating ICN with 1319 CDN, eNodeB, SGW, PGW and transport network etc.). It is important 1320 to understand that for above discussed deployment scenarios, 1321 additional study is required for lawful interception, billing/ 1322 mediation, network slicing, and provisioning APIs. 1324 Mobile Edge Computing (MEC) [CHENG] provides capabilities to deploy 1325 functionalities such as Content Delivery Network (CDN) caching and 1326 mobile user plane functions (UPF) [TS23.501]. Recent research for 1327 delivering real-time video content using ICN has also been proven to 1328 be efficient [NDNRTC] and can be used towards realizing the benefits 1329 of ICN deployment in eNodeB, MEC, mobile gateways (SGW, PGW) and CDN. 1330 The key aspect for ICN is in its seamless integration in LTE and 5G 1331 networks with tangible benefits so that we can optimize content 1332 delivery using simple and scalable architecture. Authors will 1333 continue to explore how ICN forwarding in MEC could be used in 1334 efficient data delivery from mobile edge. 1336 Based on our study of control plane signaling it is not beneficial to 1337 deploy ICN with existing protocols unless further changes are 1338 introduced in the control protocol stack itself. As mentioned in 1339 [TS23.501], 5G network architecture proposes simplification of 1340 control plane messages and can be a candidate for use of ICN. 1342 As a starting step towards ICN user plane deployment, it is 1343 recommended to incorporate protocol changes in UE, eNodeB, SGW/PGW 1344 for data transport. ICN has inherent capabilities for mobility and 1345 content caching, which can improve the efficiency of data transport 1346 for unicast and multicast delivery. Authors welcome the 1347 contributions and suggestions including those related to further 1348 validations of the principles by implementing prototype and/or proof 1349 of concept in the lab and in production environment. 1351 7. Acknowledgements 1353 We thank all contributors, reviewers and the chairs for their 1354 valuable time in providing the comments and feedback, which has 1355 helped to improve this draft. 1357 8. References 1359 8.1. Normative References 1361 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1362 Requirement Levels", BCP 14, RFC 2119, 1363 DOI 10.17487/RFC2119, March 1997, 1364 . 1366 [TS24.008] 1367 3GPP, "Mobile radio interface Layer 3 specification; Core 1368 network protocols; Stage 3", 3GPP TS 24.008 3.20.0, 1369 December 2005, 1370 . 1372 [TS25.323] 1373 3GPP, "Packet Data Convergence Protocol (PDCP) 1374 specification", 3GPP TS 25.323 3.10.0, September 2002, 1375 . 1377 [TS29.274] 1378 3GPP, "3GPP Evolved Packet System (EPS); Evolved General 1379 Packet Radio Service (GPRS) Tunnelling Protocol for 1380 Control plane (GTPv2-C); Stage 3", 3GPP TS 29.274 10.11.0, 1381 June 2013, 1382 . 1384 [TS29.281] 1385 3GPP, "General Packet Radio System (GPRS) Tunnelling 1386 Protocol User Plane (GTPv1-U)", 3GPP TS 29.281 10.3.0, 1387 September 2011, 1388 . 1390 [TS36.323] 1391 3GPP, "Evolved Universal Terrestrial Radio Access 1392 (E-UTRA); Packet Data Convergence Protocol (PDCP) 1393 specification", 3GPP TS 36.323 10.2.0, January 2013, 1394 . 1396 8.2. Informative References 1398 [ALM] Auge, J., Carofiglio, G., Grassi, G., Muscariello, L., 1399 Pau, G., and X. Zeng, "Anchor-Less Producer Mobility in 1400 ICN", Proceedings of the 2Nd ACM Conference on 1401 Information-Centric Networking, ACM-ICN'15, ACM DL, 1402 pp.189-190, September 2013, 1403 . 1405 [BROWER] Brower, E., Jeffress, L., Pezeshki, J., Jasani, R., and E. 1406 Ertekin, "Integrating Header Compression with IPsec", 1407 MILCOM 2006 - 2006 IEEE Military Communications 1408 conference IEEE Xplore DL, pp.1-6, October 2006, 1409 . 1411 [CCN] "Content Centric Networking", . 1413 [CCNxSem] Mosko, M., Solis, I., and C. Wood, "CCNx Semantics", 1414 draft-irtf-icnrg-ccnxsemantics-09 (work in progress), June 1415 2018. 1417 [CCNxTLV] Mosko, M., Solis, I., and C. Wood, "CCNx Messages in TLV 1418 Format", draft-irtf-icnrg-ccnxmessages-08 (work in 1419 progress), July 2018. 1421 [CHENG] Liang, C., Yu, R., and X. Zhang, "Information-centric 1422 network function virtualization over 5g mobile wireless 1423 networks", IEEE Network Journal vol. 29, number 3, pp. 1424 68-74, June 2015, 1425 . 1427 [EPCCUPS] Schmitt, P., Landais, B., and F. Yong Yang, "Control and 1428 User Plane Separation of EPC nodes (CUPS)", 3GPP The 1429 Mobile Broadband Standard, July 2017, 1430 . 1432 [GALIS] Galis, A., Makhijani, K., Yu, D., and B. Liu, "Autonomic 1433 Slice Networking", draft-galis-anima-autonomic-slice- 1434 networking-05 (work in progress), September 2018. 1436 [GRAYSON] Grayson, M., Shatzkamer, M., and S. Wainner, "Cisco Press 1437 book "IP Design for Mobile Networks"", Cisco 1438 Press Networking Technology series, June 2009, 1439 . 1442 [H2020] H2020, "The POINT Project", . 1444 [HICN] Muscariello, L., Carofiglio, G., Auge, J., and M. 1445 Papalini, "Hybrid Information-Centric Networking", draft- 1446 muscariello-intarea-hicn-00 (work in progress), June 2018. 1448 [ICN5G] Ravindran, R., suthar, P., Trossen, D., and G. White, 1449 "Enabling ICN in 3GPP's 5G NextGen Core Architecture", 1450 draft-ravi-icnrg-5gc-icn-02 (work in progress), July 2018. 1452 [ICNQoS] Al-Naday, M., Bontozoglou, A., Vassilakis, G., and M. 1453 Reed, "Quality of Service in an Information-Centric 1454 Network", 2014 IEEE Global Communications Conference IEEE 1455 Xplore DL, pp. 1861-1866, December 2014, 1456 . 1458 [IPoICN] Trossen, D., Read, M., Riihijarvi, J., Georgiades, M., 1459 Fotiou, N., and G. Xylomenos, "IP over ICN - The better 1460 IP?", 2015 European Conference on Networks and 1461 Communications (EuCNC) IEEE Xplore DL, pp. 413-417, June 1462 2015, . 1464 [MECSPEC] "Mobile Edge Computing (MEC); Framework and Reference 1465 Architecture", ETSI European Telecommunication Standards 1466 Institute (ETSI) MEC specification, March 2016, 1467 . 1470 [NDNRTC] Gusev, P., Wang, Z., Burke, J., Zhang, L., Yoneda, T., 1471 Ohnishi, R., and E. Muramoto, "Real-time Streaming Data 1472 Delivery over Named Data Networking,", IEICE Transactions 1473 on Communications vol. E99.B, pp. 974-991, May 2016, 1474 . 1476 [NGMN] Robson, J., "Data Offloading Techniques in Cellular 1477 Networks: A Survey", Next Generation Mobile Networks, LTE- 1478 Advanced Transport Provisioning, V0.0.14, October 2015, 1479 . 1482 [NS3EPC] Baldo, N., "The ns-3 EPC module", NS3 EPC Model, 1483 . 1486 [NS3LTE] Baldo, N., "The ns-3 LTE module", NS3 LTE Model, 1487 . 1490 [OFFLOAD] Rebecchi, F., Dias de Amorim, M., Conan, V., Passarella, 1491 A., Bruno, R., and M. Conti, "Data Offloading Techniques 1492 in Cellular Networks: A Survey", IEEE Communications 1493 Surveys and Tutorials, IEEE Xplore DL, vol:17, issue:2, 1494 pp.580-603, November 2014, 1495 . 1497 [OLTEANU] Olteanu, A. and P. Xiao, "Fragmentation and AES Encryption 1498 Overhead in Very High-speed Wireless LANs", Proceedings of 1499 the 2009 IEEE International Conference on Communications 1500 ICC'09, ACM DL, pp.575-579, June 2009, 1501 . 1503 [RFC4594] Babiarz, J., Chan, K., and F. Baker, "Configuration 1504 Guidelines for DiffServ Service Classes", RFC 4594, 1505 DOI 10.17487/RFC4594, August 2006, 1506 . 1508 [RFC6459] Korhonen, J., Ed., Soininen, J., Patil, B., Savolainen, 1509 T., Bajko, G., and K. Iisakkila, "IPv6 in 3rd Generation 1510 Partnership Project (3GPP) Evolved Packet System (EPS)", 1511 RFC 6459, DOI 10.17487/RFC6459, January 2012, 1512 . 1514 [RFC7476] Pentikousis, K., Ed., Ohlman, B., Corujo, D., Boggia, G., 1515 Tyson, G., Davies, E., Molinaro, A., and S. Eum, 1516 "Information-Centric Networking: Baseline Scenarios", 1517 RFC 7476, DOI 10.17487/RFC7476, March 2015, 1518 . 1520 [RFC7927] Kutscher, D., Ed., Eum, S., Pentikousis, K., Psaras, I., 1521 Corujo, D., Saucez, D., Schmidt, T., and M. Waehlisch, 1522 "Information-Centric Networking (ICN) Research 1523 Challenges", RFC 7927, DOI 10.17487/RFC7927, July 2016, 1524 . 1526 [SDN5G] Page, J. and J. Dricot, "Software-defined networking for 1527 low-latency 5G core network", 2016 International 1528 Conference on Military Communications and Information 1529 Systems (ICMCIS) IEEE Xplore DL, pp. 1-7, May 2016, 1530 . 1532 [TS23.203] 1533 3GPP, "Policy and charging control architecture", 3GPP 1534 TS 23.203 10.9.0, September 2013, 1535 . 1537 [TS23.401] 1538 3GPP, "General Packet Radio Service (GPRS) enhancements 1539 for Evolved Universal Terrestrial Radio Access Network 1540 (E-UTRAN) access", 3GPP TS 23.401 10.10.0, March 2013, 1541 . 1543 [TS23.501] 1544 3GPP, "System Architecture for the 5G System", 3GPP 1545 TS 23.501 15.2.0, June 2018, 1546 . 1548 [TS23.714] 1549 3GPP, "Technical Specification Group Services and System 1550 Aspects: Study on control and user plane separation of EPC 1551 nodes", 3GPP TS 23.714 0.2.2, June 2016, 1552 . 1554 [TS29.060] 1555 3GPP, "General Packet Radio Service (GPRS); GPRS 1556 Tunnelling Protocol (GTP) across the Gn and Gp interface", 1557 3GPP TS 29.060 3.19.0, March 2004, 1558 . 1560 [TS33.310] 1561 3GPP, "Network Domain Security (NDS); Authentication 1562 Framework (AF)", 3GPP TS 33.310 10.7.0, December 2012, 1563 . 1565 [TS33.320] 1566 3GPP, "Security of Home Node B (HNB) / Home evolved Node B 1567 (HeNB)", 3GPP TS 33.320 10.5.0, June 2012, 1568 . 1570 Authors' Addresses 1572 Prakash Suthar 1573 Cisco Systems 1574 9501 Technology Blvd 1575 Rosemont, Illinois 56018 1576 USA 1578 Email: psuthar@cisco.com 1580 Milan Stolic 1581 Cisco Systems 1582 9501 Technology Blvd 1583 Rosemont, Illinois 56018 1584 USA 1586 Email: mistolic@cisco.com 1588 Anil Jangam (editor) 1589 Cisco Systems 1590 3600 Cisco Way 1591 San Jose, California 95134 1592 USA 1594 Email: anjangam@cisco.com 1596 Dirk Trossen 1597 InterDigital Inc. 1598 64 Great Eastern Street, 1st Floor 1599 London EC2A 3QR 1600 United Kingdom 1602 Email: Dirk.Trossen@InterDigital.com 1604 Ravishankar Ravindran 1605 Huawei Technologies 1606 2330 Central Expressway 1607 Santa Clara, California 95050 1608 USA 1610 Email: ravi.ravindran@huawei.com