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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: November 8, 2020 Cisco Systems Inc. 6 Dirk Trossen 7 Huawei Technologies 8 Ravishankar Ravindran 9 Sterlite Technologies 10 May 07, 2020 12 Native Deployment of ICN in LTE, 4G Mobile Networks 13 draft-irtf-icnrg-icn-lte-4g-06 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 the 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 a bandwidth and routing 24 perspective, this approach is inefficient. Multicast and broadcast 25 technologies have emerged recently for mobile networks, but their 26 deployments are very limited or at an experimental stage due to 27 complex architecture and radio spectrum issues. ICN is a rapidly 28 emerging technology with built-in features for efficient multimedia 29 data delivery. However much of the work is focused on fixed 30 networks. The focus of this draft is on native deployment of ICN in 31 cellular mobile networks by using ICN in a 3GPP protocol stack. ICN 32 has an inherent capability for multicast, anchorless mobility and 33 security, and it is optimized for data delivery using local caching 34 at the edge. The proposed approaches in this draft allow ICN to be 35 enabled natively over the current LTE stack comprising PDCP/RLC/MAC/ 36 PHY, or in a dual stack mode (along with IP). These approaches can 37 help optimize the mobile networks by leveraging the inherent benefits 38 of ICN. This document is a product of the Information-Centric 39 Networking Research Group (ICNRG). 41 Status of This Memo 43 This Internet-Draft is submitted in full conformance with the 44 provisions of BCP 78 and BCP 79. 46 Internet-Drafts are working documents of the Internet Engineering 47 Task Force (IETF). Note that other groups may also distribute 48 working documents as Internet-Drafts. The list of current Internet- 49 Drafts is at https://datatracker.ietf.org/drafts/current/. 51 Internet-Drafts are draft documents valid for a maximum of six months 52 and may be updated, replaced, or obsoleted by other documents at any 53 time. It is inappropriate to use Internet-Drafts as reference 54 material or to cite them other than as "work in progress." 56 This Internet-Draft will expire on November 8, 2020. 58 Copyright Notice 60 Copyright (c) 2020 IETF Trust and the persons identified as the 61 document authors. All rights reserved. 63 This document is subject to BCP 78 and the IETF Trust's Legal 64 Provisions Relating to IETF Documents 65 (https://trustee.ietf.org/license-info) in effect on the date of 66 publication of this document. Please review these documents 67 carefully, as they describe your rights and restrictions with respect 68 to this document. Code Components extracted from this document must 69 include Simplified BSD License text as described in Section 4.e of 70 the Trust Legal Provisions and are provided without warranty as 71 described in the Simplified BSD License. 73 Table of Contents 75 1. 3GPP Terminology and Concepts . . . . . . . . . . . . . . . . 3 76 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 7 77 3. LTE, 4G Mobile Network . . . . . . . . . . . . . . . . . . . 7 78 3.1. Network Overview . . . . . . . . . . . . . . . . . . . . 7 79 3.2. QoS Challenges . . . . . . . . . . . . . . . . . . . . . 9 80 3.3. Data Transport Using IP . . . . . . . . . . . . . . . . . 10 81 3.4. Virtualizing Mobile Networks . . . . . . . . . . . . . . 11 82 4. Data Transport Using ICN . . . . . . . . . . . . . . . . . . 11 83 5. ICN Deployment in 4G and LTE Networks . . . . . . . . . . . . 14 84 5.1. General ICN Deployment Considerations . . . . . . . . . . 14 85 5.2. ICN Deployment Scenarios . . . . . . . . . . . . . . . . 14 86 5.3. ICN Deployment in LTE Control Plane . . . . . . . . . . . 18 87 5.4. ICN Deployment in LTE User Plane . . . . . . . . . . . . 19 88 5.4.1. Dual stack ICN deployments in UE . . . . . . . . . . 20 89 5.4.2. Native ICN Deployments in UE . . . . . . . . . . . . 24 90 5.5. ICN Deployment in eNodeB . . . . . . . . . . . . . . . . 25 91 5.6. ICN Deployment in Packet Core (SGW, PGW) Gateways . . . . 27 92 6. Security Considerations . . . . . . . . . . . . . . . . . . . 29 93 7. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 94 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 31 95 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 31 96 9.1. Normative References . . . . . . . . . . . . . . . . . . 31 97 9.2. Informative References . . . . . . . . . . . . . . . . . 32 98 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 36 100 1. 3GPP Terminology and Concepts 102 1. Access Point Name 104 The Access Point Name (APN) is a Fully Qualified Domain Name 105 (FQDN) and resolves to a set of gateways in an operator's 106 network. APN identifies the packet data network (PDN) with 107 which a mobile data user wants to communicate. In addition to 108 identifying a PDN, an APN may also be used to define the type of 109 service, QoS, and other logical entities inside GGSN, PGW. 111 2. Control Plane 113 The control plane carries signaling traffic and is responsible 114 for routing between eNodeB and MME, MME and HSS, MME and SGW, 115 SGW and PGW, etc. Control plane signaling is required to 116 authenticate and authorize UE and establish a mobility session 117 with mobile gateways (SGW/PGW). Control plane functions also 118 include system configuration and management. 120 3. Dual Address PDN/PDP Type 122 The dual address Packet Data Network/Packet Data Protocol (PDN/ 123 PDP) Type (IPv4v6) is used in 3GPP context, in many cases as a 124 synonym for dual stack; i.e., a connection type capable of 125 serving IPv4 and IPv6 simultaneously. 127 4. eNodeB 129 The eNodeB is a base station entity that supports the Long-Term 130 Evolution (LTE) air interface. 132 5. Evolved Packet Core 134 The Evolved Packet Core (EPC) is an evolution of the 3GPP GPRS 135 system characterized by a higher-data-rate, lower-latency, 136 packet-optimized system. The EPC comprises some sub components 137 of the EPS core such as Mobility Management Entity (MME), 138 Serving Gateway (SGW), Packet Data Network Gateway (PDN-GW), and 139 Home Subscriber Server (HSS). 141 6. Evolved Packet System 142 The Evolved Packet System (EPS) is an evolution of the 3GPP GPRS 143 system characterized by a higher-data-rate, lower-latency, 144 packet-optimized system that supports multiple Radio Access 145 Technologies (RATs). The EPS comprises the EPC together with 146 the Evolved Universal Terrestrial Radio Access (E-UTRA) and the 147 Evolved Universal Terrestrial Radio Access Network (E-UTRAN). 149 7. Evolved UTRAN 151 The E-UTRAN is a communications network sometimes referred to as 152 4G, and consists of eNodeB (4G base stations). The E-UTRAN 153 allows connectivity between the User Equipment and the core 154 network. 156 8. GPRS Tunneling Protocol 158 The GPRS Tunneling Protocol (GTP) [TS29.060] [TS29.274] 159 [TS29.281] is a tunneling protocol defined by 3GPP. It is a 160 network-based mobility protocol and is like Proxy Mobile IPv6 161 (PMIPv6). However, GTP also provides functionality beyond 162 mobility, such as in-band signaling related to QoS and charging, 163 among others. 165 9. Gateway GPRS Support Node 167 The Gateway GPRS Support Node (GGSN) is a gateway function in 168 the GPRS and 3G network that provides connectivity to the 169 Internet or other PDNs. The host attaches to a GGSN identified 170 by an APN assigned to it by an operator. The GGSN also serves 171 as the topological anchor for addresses/prefixes assigned to the 172 User Equipment. 174 10. General Packet Radio Service 176 The General Packet Radio Service (GPRS) is a packet-oriented 177 mobile data service available to users of the 2G and 3G cellular 178 communication systems--the GSM--specified by 3GPP. 180 11. Home Subscriber Server 182 The Home Subscriber Server (HSS) is a database for a given 183 subscriber and was introduced in 3GPP Release-5. It is the 184 entity containing subscription-related information to support 185 the network entities that handle calls/sessions. 187 12. Mobility Management Entity 188 The Mobility Management Entity (MME) is a network element 189 responsible for control-plane functionalities, including 190 authentication, authorization, bearer management, layer-2 191 mobility, and so on. The MME is essentially the control-plane 192 part of the SGSN in the GPRS. The user-plane traffic bypasses 193 the MME. 195 13. Public Land Mobile Network 197 The Public Land Mobile Network (PLMN) is a network operated by a 198 single administration. A PLMN (and, therefore, also an 199 operator) is identified by the Mobile Country Code (MCC) and the 200 Mobile Network Code (MNC). Each (telecommunications) operator 201 providing mobile services has its own PLMN. 203 14. Policy and Charging Control 205 The Policy and Charging Control (PCC) framework is used for QoS 206 policy and charging control. It has two main functions: flow- 207 based charging (including online credit control), and policy 208 control (for example, gating control, QoS control, and QoS 209 signaling). It is optional to 3GPP EPS but needed if dynamic 210 policy and charging control by means of PCC rules based on user 211 and services are desired. 213 15. Packet Data Network 215 The Packet Data Network (PDN) is a packet-based network that 216 either belongs to the operator or is an external network such as 217 the Internet or a corporate intranet. The user eventually 218 accesses services in one or more PDNs. The operator's packet 219 core networks are separated from packet data networks either by 220 GGSNs or PDN Gateways (PGWs). 222 16. Serving Gateway 224 The Serving Gateway (SGW) is a gateway function in the EPS, 225 which terminates the interface towards the E-UTRAN. The SGW is 226 the Mobility Anchor point for layer-2 mobility (inter-eNodeB 227 handovers). For each UE connected with the EPS, there is only 228 one SGW at any given point in time. The SGW is essentially the 229 user-plane part of the GPRS's SGSN. 231 17. Packet Data Network Gateway 233 The Packet Data Network Gateway (PGW) is a gateway function in 234 the Evolved Packet System (EPS), which provides connectivity to 235 the Internet or other PDNs. The host attaches to a PGW 236 identified by an APN assigned to it by an operator. The PGW 237 also serves as the topological anchor for addresses/prefixes 238 assigned to the User Equipment. 240 18. Packet Data Protocol Context 242 A Packet Data Protocol (PDP) context is the equivalent of a 243 virtual connection between the User Equipment (UE) and a PDN 244 using a specific gateway. 246 19. Packet Data Protocol Type 248 A Packet Data Protocol Type (PDP Type) identifies the used/ 249 allowed protocols within the PDP context. Examples are IPv4, 250 IPv6, and IPv4v6 (dual-stack). 252 20. Serving GPRS Support Node 254 The Serving GPRS Support Node (SGSN) is a network element 255 located between the radio access network (RAN) and the gateway 256 (GGSN). A per-UE point-to-point (p2p) tunnel between the GGSN 257 and SGSN transports the packets between the UE and the gateway. 259 21. Terminal Equipment 261 The Terminal Equipment (TE) is any device/host connected to the 262 Mobile Terminal (MT) offering services to the user. A TE may 263 communicate to an MT, for example, over the Point-to-Point 264 Protocol (PPP). 266 22. UE, MS, MN, and Mobile 268 The terms User Equipment (UE), Mobile Station (MS), Mobile Node 269 (MN), and mobile refer to the devices that are hosts with the 270 ability to obtain Internet connectivity via a 3GPP network. An 271 MS comprises the Terminal Equipment (TE) and a Mobile Terminal 272 (MT). The terms UE, MS, MN, and mobile are used interchangeably 273 within this document. 275 23. User Plane 277 The user plane refers to data traffic and the required bearers 278 for the data traffic. In practice, IP is the only data traffic 279 protocol used in the user plane. 281 2. Introduction 283 LTE mobile technology is built as an all-IP network. It uses IP 284 routing protocols (OSPF, ISIS, BGP, etc.) to establish network routes 285 to route data traffic to the end user's device. Stickiness of an IP 286 address to a device is the key to get connected to a mobile network. 287 The same IP address is maintained through the session until the 288 device gets detached or moves to another network. 290 One of the key protocols used in 4G and LTE networks is GPRS 291 Tunneling protocol (GTP). GTP, DIAMETER and other protocols are 292 built on top of IP. One of the biggest challenges with IP-based 293 routing is that it is not optimized for data transport, although it 294 is the most efficient communication protocol. By native 295 implementation of Information Centric Networking (ICN) in 3GPP, we 296 can re-architect a mobile network and optimize its design for 297 efficient data transport by leveraging ICN's caching feature. ICN 298 also offers an opportunity to leverage inherent capabilities of 299 multicast, anchorless mobility management, and authentication. This 300 draft proposes options for deploying ICN in mobile networks, and how 301 they affect mobile providers and end users. 303 This document represents the consensus of the Information-Centric 304 Networking Research Group (ICNRG). It has been reviewed extensively 305 by the Research Group (RG) members active in the specific areas of 306 work covered by the document. 308 3. LTE, 4G Mobile Network 310 3.1. Network Overview 312 With the introduction of LTE, mobile networks moved to all-IP 313 transport for all elements such as eNodeB, MME, SGW/PGW, HSS, PCRF, 314 routing and switching, etc. Although LTE network is data-centric, it 315 has support for legacy Circuit Switch features such as voice and SMS 316 through transitional CS fallback and flexible IMS deployment 317 [GRAYSON]. For each mobile device attached to the radio (eNodeB), 318 there is a separate overlay tunnel (GPRS Tunneling Protocol, GTP) 319 between eNodeB and Mobile gateways (i.e., SGW, PGW). 321 The GTP tunnel is used to carry user traffic between gateways and 322 mobile devices. This forces data to be distributed only by using 323 unicast mechanism. It is also important to understand the overhead 324 of a GTP and IPSec protocols because it has impact on the carried 325 user data traffic. All mobile backhaul traffic is encapsulated using 326 GTP tunnel, which has overhead of 8 bytes on top of IP and UDP 327 [NGMN]. Additionally, if IPSec is used for security (which is often 328 required if the Service Provider is using a shared backhaul), it adds 329 overhead based on the IPSec tunneling model (tunnel or transport), 330 and the encryption and authentication header algorithm used. If we 331 factor Advanced Encryption Standard (AES) encryption with the packet 332 size, the overhead can be significant [OLTEANU], particularly for the 333 smaller payloads. 335 When any UE is powered up, it attaches to a mobile network based on 336 its configuration and subscription. After a successful attach 337 procedure, UE registers with the mobile core network, and an IPv4 338 and/or IPv6 address is assigned. A default bearer is created for 339 each UE and it is assigned to default Access Point Name (APN). 341 +-------+ Diameter +-------+ 342 | HSS |------------| SPR | 343 +-------+ +-------+ 344 | | 345 +------+ +------+ S4 | +-------+ 346 | 3G |---| SGSN |----------------|------+ +------| PCRF | 347 ^ |NodeB | | |---------+ +---+ | | +-------+ 348 +-+ | +------+ +------+ S3 | | S6a | |Gxc | 349 | | | +-------+ | | |Gx 350 +-+ | +------------------| MME |------+ | | | 351 UE v | S1MME +-------+ S11 | | | | 352 +----+-+ +-------+ +-------+ 353 |4G/LTE|------------------------------| SGW |-----| PGW | 354 |eNodeB| S1U +-------+ +--| | 355 +------+ | +-------+ 356 +---------------------+ | | 357 S1U GTP Tunnel traffic | +-------+ | | 358 S2a GRE Tunnel traffic |S2A | ePDG |-------+ | 359 S2b GRE Tunnel traffic | +-------+ S2B |SGi 360 SGi IP traffic | | | 361 +---------+ +---------+ +-----+ 362 | Trusted | |Untrusted| | CDN | 363 |non-3GPP | |non-3GPP | +-----+ 364 +---------+ +---------+ 365 | | 366 +-+ +-+ 367 | | | | 368 +-+ +-+ 369 UE UE 371 Figure 1: LTE, 4G Mobile Network Overview 373 The data delivered to mobile devices is unicast inside the GTP 374 tunnel. If we consider the combined impact of GTP, IPSec and unicast 375 traffic, the data delivery is not efficient. IETF has developed 376 various header compression algorithms to reduce overhead associated 377 with IP packets. Some techniques are robust header compression 378 (ROHC) and enhanced compression of the real-time transport protocol 379 (ECRTP) so that impact of overhead created by GTP, IPsec, etc., is 380 reduced to some extent [BROWER]. For commercial mobile networks, 381 3GPP has adopted different mechanisms for header compression to 382 achieve efficiency in data delivery [TS25.323], and can be adapted to 383 ICN, as well [ICNLOWPAN] [TLVCOMP]. 385 3.2. QoS Challenges 387 During the attach procedure, a default bearer is created for each UE 388 and it is assigned to the default Access Point Name (APN). The QoS 389 values that uplink and downlink bandwidth assigned during the initial 390 attach are minimal. Additional dedicated bearer(s) with enhanced QoS 391 parameters are established depending on specific application needs. 393 While all traffic within a certain bearer gets the same treatment, 394 QoS parameters supporting these requirements can be very granular in 395 different bearers. These values vary for the control, management and 396 user traffic, and can be very different depending on application key 397 parameters such as latency, jitter (important for voice and other 398 real-time applications), packet loss, and queuing mechanism (strict 399 priority, low-latency, fair, and so on). 401 Implementation of QoS for mobile networks is done at two stages: at 402 content prioritization/marking and transport marking, and congestion 403 management. From the transport perspective, QoS is defined at layer 404 2 as class of service (CoS) and at layer 3 either as DiffServ code 405 point (DSCP) or type of service (ToS). The mapping of DSCP to CoS 406 takes place at layer 2/3 switching and routing elements. 3GPP has a 407 specified QoS Class Identifier (QCI), which represents different 408 types of content and equivalent mapping to DSCP at transport layer 409 [TS23.401]. However, this requires manual configuration at different 410 elements and, if there are misconfigurations at any place in the 411 path, it will not work properly. 413 In summary, QoS configuration for mobile networks for user plane (for 414 user traffic) and transport in an IP-based mobile network is complex 415 requires synchronization of parameters among different platforms. 416 Normally, QoS in IP is implemented using DiffServ, which uses hop-by- 417 hop QoS configuration at each router. Any inconsistency in IP QoS 418 configuration at routers in the forwarding path can result in a poor 419 subscriber experience (e.g., packet classified as high-priority can 420 go to a lower priority queue). By deploying ICN, we intend to 421 enhance the subscriber experience using policy-based configuration, 422 which can be associated with the named contents [ICNQoS] at the ICN 423 forwarder. Further investigation is needed to understand how QoS in 424 ICN can be implemented to meet the IP QoS requirements [RFC4594]. 426 Research papers published so far explore the possibility of 427 classifications based on name prefixes (thus addressing the problem 428 of IP QoS not being information aware), or on popularity or placement 429 (looking at a distance of a content from a requester). However, 430 focus of these research efforts is on faster routing of Interest 431 requests towards the content rather than content delivery. 433 3.3. Data Transport Using IP 435 The data delivered to mobile devices is unicast inside GTP tunnel 436 from an eNodeB to a PDN gateway (PGW), as described in 3GPP 437 specifications [TS23.401]. While the technology exists to address 438 the issue of possible multicast delivery, there are many difficulties 439 related to multicast protocol implementation on the RAN side of the 440 network. Transport networks in the backhaul and core addressed the 441 multicast delivery long ago and have implemented it in most cases in 442 their multi-purpose integrated transport. But the RAN part of the 443 network is still lagging behind due to complexities related to client 444 mobility, handovers, and the fact that the potential gain to Service 445 Providers may not justify the investment. With that said, the data 446 delivery in the mobility remains greatly unicast. Techniques to 447 handle multicast (such as LTE-B or eMBMS) have been designed to 448 handle pre-planned content delivery, such as live content, which 449 contrasts user behavior today, largely based on content (or video) on 450 demand model. 452 To ease the burden on the bandwidth of the SGi interface, caching is 453 introduced in a similar manner as with many Enterprises. In the 454 mobile networks, whenever possible, cached data is delivered. 455 Caching servers are placed at a centralized location, typically in 456 the Service Provider's Data Center, or in some cases lightly 457 distributed in Packet Core locations with the PGW nodes close to the 458 Internet and IP services access (SGi interface). This is a very 459 inefficient concept because traffic must traverse the entire backhaul 460 path for the data to be delivered to the end user. Other issues, 461 such as out-of-order delivery, contribute to this complexity and 462 inefficiency, which needs to be addressed at the application level. 464 Data delivered to mobile devices is unicast inside a GTP tunnel. If 465 we consider the combined impact of GTP, IPSec, and unicast traffic, 466 the end-to-end data delivery is not efficient. By deploying ICN, we 467 intend to either terminate the GTP tunnel at the mobility anchoring 468 point by leveraging control and user-plane separation, or replace it 469 with native ICN protocols. 471 3.4. Virtualizing Mobile Networks 473 The Mobile packet core deployed in a major Service Provider network 474 is either based on dedicated hardware or, in some cases, large 475 capacity x86 platforms. With adoption of Mobile Virtual Network 476 Operators (MVNO), public safety network, and enterprise mobility 477 network, we need elastic mobile core architecture. By deploying 478 mobile packet core on a commercially off-the-shelf (COTS) platform 479 using virtualized infrastructure (NFVI) framework and end-to-end 480 orchestration, we can simplify new deployments and provide optimized 481 TCO. 483 While virtualization is growing, and many mobile providers use hybrid 484 architecture consisting of dedicated and virtualized infrastructures, 485 the control and data delivery planes are still the same. There is 486 also work under way to separate the control plane and user plane so 487 the network can scale better. Virtualized mobile networks and 488 network slicing with control and user plane separation provide 489 mechanism to evolve GTP-based architecture to open-flow SDN-based 490 signaling for LTE and proposed 5G core. Some early architecture work 491 for 5G mobile technologies provides a mechanism for control and user 492 plane separation and simplifies mobility call flow by introduction of 493 open-flow-based signaling [ICN5G]. This has been considered by 3GPP 494 [EPCCUPS] and is also described in [SDN5G]. 496 4. Data Transport Using ICN 498 For mobile devices, the edge connectivity to the network is between 499 radio and a router or mobile edge computing (MEC) [MECSPEC] element. 500 MEC has the capability of processing client requests and segregating 501 control and user traffic at the edge of radio, rather than sending 502 all requests to the mobile gateway. 504 +----------+ 505 | Content +----------------------------------------+ 506 | Publisher| | 507 +---+---+--+ | 508 | | +--+ +--+ +--+ | 509 | +--->|R1|------------>|R2|---------->|R4| | 510 | +--+ +--+ +--+ | 511 | | Cached | 512 | v content | 513 | +--+ at R3 | 514 | +========|R3|---+ | 515 | # +--+ | | 516 | # | | 517 | v v | 518 | +-+ +-+ | 519 +---------------| |-------------| |-------------+ 520 +-+ +-+ 521 Consumer-1 Consumer-2 522 UE UE 524 ===> Content flow from cache 525 ---> Content flow from publisher 527 Figure 2: ICN Architecture 529 MEC transforms radio into an intelligent service edge capable of 530 delivering services directly from the edge of the network, while 531 providing the best possible performance to the client. MEC can be an 532 ideal candidate for ICN forwarder in addition to its usual function 533 of managing mobile termination. In addition to MEC, other transport 534 elements, such as routers, can work as ICN forwarders. 536 Data transport using ICN is different compared to IP-based transport. 537 It evolves the Internet infrastructure by introducing uniquely named 538 data as a core Internet principle. Communication in ICN takes place 539 between the content provider (producer) and the end user (consumer), 540 as described in Figure 2. 542 Every node in a physical path between a client and a content provider 543 is called the ICN forwarder or router. It can route the request 544 intelligently and to cache the content so it can be delivered locally 545 for subsequent request from any other client. For mobile network, 546 transport between a client and a content provider consists of radio 547 network + mobile backhaul and IP core transport + Mobile Gateways + 548 Internet + content data network (CDN). 550 To understand the suitability of ICN for mobile networks, we will 551 discuss the ICN framework describing protocols architecture and 552 different types of messages, and then consider how we can use this in 553 a mobile network for delivering content more efficiently. ICN uses 554 two types of packets called "interest packet" and "data packet" as 555 described in Figure 3. 557 +------------------------------------+ 558 Interest | +------+ +------+ +------+ | +-----+ 559 +-+ ---->| CS |---->| PIT |---->| FIB |--------->| CDN | 560 | | | +------+ +------+ +------+ | +-----+ 561 +-+ | | Add | Drop | | Forward 562 UE <--------+ Intf v Nack v | 563 Data | | 564 +------------------------------------+ 566 +------------------------------------+ 567 +-+ | Forward +------+ | +-----+ 568 | | <-------------------------------------| PIT |<---------| CDN | 569 +-+ | | Cache +--+---+ | Data +-----+ 570 UE | +--v---+ | | 571 | | CS | v | 572 | +------+ Discard | 573 +------------------------------------+ 575 Figure 3: ICN Interest, Data Packet and Forwarder 577 In an LTE network, when a mobile device wants to get certain content, 578 it will send an Interest message to the closest eNodeB. Interest 579 packet follows the TLV format [RFC8609] and contains mandatory fields 580 such as name of the content and content matching restrictions 581 (KeyIdRestr and ContentObjectHashRestr) forming the tuple [RFC8569]. 582 The content matching tuple uniquely identifies the matching data 583 packet for the given Interest packet. Another attribute called 584 HopLimit is used to detect looping Interest messages. 586 An ICN router will receive an Interest packet and perform lookup if a 587 request for such content has come earlier from another client. If 588 yes, it is served from the local cache; otherwise, the request is 589 forwarded to the next-hop ICN router. Each ICN router maintains 590 three data structures: Pending Interest Table (PIT), Forwarding 591 Information Base (FIB), and Content Store (CS). The Interest packet 592 travels hop-by-hop towards the content provider. Once the Interest 593 reaches the content provider, it will return a Data packet containing 594 information such as content name, signature, and data. 596 Data packet travels in reverse direction following the same path 597 taken by the Interest packet, which maintains routing symmetry. 598 Details about algorithms used in PIT, FIB, CS, and security trust 599 models are described in various resources [CCN]; here, we have 600 explained the concept and its applicability to the LTE network. 602 5. ICN Deployment in 4G and LTE Networks 604 5.1. General ICN Deployment Considerations 606 In LTE/4G mobile networks, both user and control plane traffic have 607 to be transported from the edge to the mobile packet core via IP 608 transport. The evolution of existing mobile packet core using 609 Control and User Plane Separation (CUPS) [TS23.714] enables flexible 610 network deployment and operation, by distributed deployment and the 611 independent scaling between control plane and user plane functions - 612 while not affecting the functionality of existing nodes subject to 613 this split. 615 In the CUPS architecture, there is an opportunity to shorten the path 616 for user plane traffic by deploying offload nodes closer to the edge 617 [OFFLOAD]. With this major architecture change, a User Plane 618 Function (UPF) node is placed close to the edge so traffic no longer 619 needs to traverse the entire backhaul path to reach the EPC. In many 620 cases, where feasible, UPF can be collocated with the eNodeB, which 621 is also a business decision based on user demand. Placing a 622 Publisher close to the offload site, or at the offload site, provides 623 for a significant improvement in user experience, especially with 624 latency-sensitive applications. This optimization allows for the 625 introduction of ICN and amplifies its advantages. This section 626 analyzes the potential impact of ICN on control and user plane 627 traffic for centralized and disaggregate CUPS-based mobile network 628 architecture. 630 5.2. ICN Deployment Scenarios 632 Deployment of ICN provides an opportunity to further optimize the 633 existing data transport in LTE/4G mobile networks. The various 634 deployment options that ICN and IP provide are somewhat analogous to 635 the deployment scenarios when IPv6 was introduced to interoperate 636 with IPv4 except, with ICN, the whole IP stack is being replaced. We 637 have reviewed [RFC6459] and analyzed the impact of ICN on control 638 plane signaling and user plane data delivery. In general, ICN can be 639 deployed by natively replacing IP transport (IPv4 and IPv6) or as an 640 overlay protocol. Figure 4 describes a modified protocol stack to 641 support ICN deployment scenarios. 643 +----------------+ +-----------------+ 644 | ICN App (new) | |IP App (existing)| 645 +---------+------+ +-------+---------+ 646 | | 647 +---------+----------------+---------+ 648 | Transport Convergence Layer (new) | 649 +------+---------------------+-------+ 650 | | 651 +------+------+ +------+-------+ 652 |ICN function | | IP function | 653 | (New) | | (Existing) | 654 +------+------+ +------+-------+ 655 | | 656 (```). (```). 657 ( ICN '`. ( IP '`. 658 ( Cloud ) ( Cloud ) 659 ` __..'+' ` __..'+' 661 Figure 4: IP/ICN Convergence and Deployment Scenarios 663 As shown in Figure 4, for applications running either in UE or in 664 content provider system to use the new transport option, we propose a 665 new transport convergence layer (TCL). This transport convergence 666 layer helps determine the type of transport (such as ICN or IP), as 667 well as the type of radio interface (LTE or WiFi or both) used to 668 send and receive traffic based on preference (e.g., content location, 669 content type, content publisher, congestion, cost, QoS). It helps 670 configure and determine the type of connection, as well as the 671 overlay mode (ICNoIP or IPoICN) between application and the protocol 672 stack (IP or ICN), to be used. 674 Combined with the existing IP function, the ICN function provides 675 support for either native ICN and/or the dual stack (ICN/IP) 676 transport functionality. See Section 5.4.1 for elaborate 677 descriptions of these functional layers. 679 The TCL can use several mechanisms for transport selection . It can 680 use a per-application configuration through a management interface, 681 possibly even a user-facing setting realized through a user 682 interface, like those used today that select cellular over WiFi being 683 used for selected applications. In another option, it might use a 684 software API, which an adapted IP application could use to specify 685 (such as an ICN transport) for obtaining its benefits. 687 Another potential application of TCL is in implementation of network 688 slicing, where it can have a slice management capability locally or 689 it can interface to an external slice manager through an API [GALIS]. 691 This solution can enable network slicing for IP and ICN transport 692 selection from the UE itself. The TCL could apply slice settings to 693 direct certain traffic (or applications) over one slice and others 694 over another slice, determined by some form of 'slicing policy'. 695 Slicing policy can be obtained externally from the slice manager or 696 configured locally on UE. 698 From the perspective of applications either on UE or a content 699 provider, the following options are possible for ICN deployment 700 natively and/or with IP. 702 1. IP over IP 704 In this scenario, UE uses applications tightly integrated with 705 the existing IP transport infrastructure. In this option, the 706 TCL has no additional function because packets are forwarded 707 directly using an IP protocol stack, which sends packets over the 708 IP transport. 710 2. ICN over ICN 712 Similar to case 1, ICN applications integrate tightly with the 713 ICN transport infrastructure. The TCL has no additional 714 responsibility because packets are forwarded directly using ICN 715 protocol stack, which sends packets over the ICN transport. 717 3. ICN over IP (ICNoIP) 719 In this scenario, the underlying IP transport infrastructure is 720 not impacted (that is, ICN is implemented as an IP overlay 721 between user equipment (UE) and content provider). IP routing is 722 used from Radio Access Network (eNodeB) to mobile backhaul, IP 723 core, and Mobile Gateway (SGW/PGW). UE attaches to Mobile 724 Gateway (SGW/PGW) using IP address. Also, the data transport 725 between Mobile Gateway (SGW/PGW) and content publisher uses IP. 726 Content provider can serve content either using IP or ICN, based 727 on the UE request. 729 An approach to implement ICN in mobile backhaul networks is 730 described in [MBICN]. It implements a GTP-U extension header 731 option to encapsulate ICN payload in GTP tunnel. However, as 732 this design runs ICN as an IP overlay, the mobile backhaul can be 733 deployed using native IP. The proposal describes a mechanism 734 where GTP-U tunnel can be terminated by hairpinning the packet 735 before it reaches SGW, if an ICN-enabled node is deployed in the 736 mobile backhaul (that is, between eNodeB and SGW). This could be 737 useful when an ICN data packet is stored in the ICN node (such as 738 repos, caches) in the tunnel path; it can reply right away 739 without going all the way through the mobile core. While GTP-U 740 extension header is used to carry UE specific ICN payload, they 741 are not visible to the transport, including SGW. On the other 742 hand, the PGW can use the UE-specific ICN header extension and 743 ICN payload to set up an uplink transport towards content 744 provider in the Internet. In addition, the design assumes a 745 proxy function at the edge, to perform ICN data retrieval on 746 behalf of a non-ICN end device. 748 4. IP over ICN (IPoICN) 750 H2020 project [H2020] provides an architectural framework for 751 deployment of IP as an overlay over ICN protocol [IPoICN]. 752 Implementing IP services over ICN provides an opportunity 753 leveraging benefit of ICN in the transport infrastructure and 754 there is no impact on end devices (UE and access network) as they 755 continue to use IP. IPoICN however, will require an inter- 756 working function (IWF/Border Gateway) to translate various 757 transport primitives. The IWF function will provide a mechanism 758 for protocol translation between IPoICN and native IP deployment 759 for mobile network. After reviewing [IPoICN], we understand and 760 interpret that ICN is implemented in the transport natively; 761 however, IP is implemented in UE, eNodeB, and Mobile gateway 762 (SGW/PGW), which is also called as a network attach point (NAP). 764 For this, said NAP receives an incoming IP or HTTP packet (the 765 latter through TCP connection termination) and publishes the 766 packet under a suitable ICN name (i.e., the hash over the 767 destination IP address for an IP packet or the hash over the FQDN 768 of the HTTP request for an HTTP packet) to the ICN network. In 769 the HTTP case, the NAP maintains a pending request mapping table 770 to map returning responses to the terminated TCP connection. 772 5. Hybrid ICN (hICN) 774 An alternative approach to implement ICN over IP is provided in 775 Hybrid ICN [HICN]. It describes a novel approach to integrate 776 ICN into IPv6 without creating overlays with a new packet format 777 as an encapsulation. hICN addresses the content by encoding a 778 location-independent name in an IPv6 address. It uses two name 779 components--name prefix and name suffix--that identify the source 780 of data and the data segment within the scope of the name prefix, 781 respectively. 783 At application layer, hICN maps the name into an IPv6 prefix and, 784 thus, uses IP as transport. As long as the name prefixes, which 785 are routable IP prefixes, point towards a mobile GW (PGW or local 786 breakout, such as CUPS), there are potentially no updates 787 required to any of the mobile core gateways (for example, SGW/ 788 PGW). The IPv6 backhaul routes the packets within the mobile 789 core. hICN can run in the UE, in the eNodeB, in the mobile 790 backhaul, or in the mobile core. Finally, as hICN itself uses 791 IPv6, it cannot be considered as an alternative transport layer. 793 5.3. ICN Deployment in LTE Control Plane 795 In this section, we analyze signaling messages that are required for 796 different procedures, such as attach, handover, tracking area update, 797 and so on. The goal of this analysis is to see if there are any 798 benefits to replacing IP-based protocols with ICN for LTE signaling 799 in the current architecture. It is important to understand the 800 concept of point of attachment (POA). When UE connects to a network, 801 it has the following POAs: 803 1. eNodeB managing location or physical POA 805 2. Authentication and Authorization (MME, HSS) managing identity or 806 authentication POA 808 3. Mobile Gateways (SGW, PGW) managing logical or session management 809 POA 811 In the current architecture, IP transport is used for all messages 812 associated with the control plane for mobility and session 813 management. IP is embedded very deeply into these messages and TLV, 814 carrying additional attributes such as a layer 3 transport. Physical 815 POA in eNodeB handles both mobility and session management for any UE 816 attached to 4G, LTE network. The number of mobility management 817 messages between different nodes in an LTE network per signaling 818 procedure are shown in Table 1. 820 Normally, two types of UE devices attach to the LTE network: SIM 821 based (need 3GPP mobility protocol for authentication) or non-SIM 822 based (which connect to WiFi network). Both device types require 823 authentication . For non-SIM based devices, AAA is used for 824 authentication. We do not propose to change UE authentication or 825 mobility management messaging for user data transport using ICN. A 826 separate study would be required to analyze the impact of ICN on 827 mobility management messages structures and flows. We are merely 828 analyzing the viability of implementing ICN as a transport for 829 control plane messages. 831 It is important to note that, if MME and HSS do not support ICN 832 transport, they still need to support UE capable of dual stack or 833 native ICN. When UE initiates an attach request using the identity 834 as ICN, MME must be able to parse that message and create a session. 836 MME forwards UE authentication to HSS, so HSS must be able to 837 authenticate an ICN-capable UE and authorize create session 838 [TS23.401]. 840 +---------------------------+-----+-----+-----+-----+------+ 841 | LTE Signaling Procedures | MME | HSS | SGW | PGW | PCRF | 842 +---------------------------+-----+-----+-----+-----+------+ 843 | Attach | 10 | 2 | 3 | 2 | 1 | 844 | Additional default bearer | 4 | 0 | 3 | 2 | 1 | 845 | Dedicated bearer | 2 | 0 | 2 | 2 | 0 | 846 | Idle-to-connect | 3 | 0 | 1 | 0 | 0 | 847 | Connect-to-Idle | 3 | 0 | 1 | 0 | 0 | 848 | X2 handover | 2 | 0 | 1 | 0 | 0 | 849 | S1 handover | 8 | 0 | 3 | 0 | 0 | 850 | Tracking area update | 2 | 2 | 0 | 0 | 0 | 851 | Total | 34 | 2 | 14 | 6 | 3 | 852 +---------------------------+-----+-----+-----+-----+------+ 854 Table 1: Signaling Messages in LTE Gateways 856 Anchorless mobility [ALM] provides a fully decentralized, control- 857 plane agnostic solution to handle producer mobility in ICN. Mobility 858 management at layer-3 level makes it access agnostic and transparent 859 to the end device or the application. The solution discusses 860 handling mobility without having to depend on core network functions 861 (e.g. MME); however, a location update to the core network may still 862 be required to support legal compliance requirements such as lawful 863 intercept and emergency services. These aspects are open for further 864 study. 866 One of the advantages of ICN is in the caching and reusing of the 867 content, which does not apply to the transactional signaling 868 exchange. After analyzing LTE signaling call flows [TS23.401] and 869 messages inter-dependencies (see Table 1), our recommendation is that 870 it is not beneficial to deploy ICN for control plane and mobility 871 management functions. Among the features of ICN design, Interest 872 aggregation and content caching are not applicable to control plane 873 signaling messages. Control plane messages are originated and 874 consumed by the applications and they cannot be shared. 876 5.4. ICN Deployment in LTE User Plane 878 We will consider Figure 1 to discuss different mechanisms to deploy 879 ICN in mobile networks. In Section 5.2, we discussed generic 880 deployment scenarios of ICN. In this section, we discuss the 881 specific use cases of native ICN deployment in LTE user plane. We 882 consider the following options: 884 1. Dual stack ICN deployment in UE 886 2. Native ICN deployments in UE 888 3. ICN deployment in eNodeB 890 4. ICN deployment in mobile gateways (SGW/PGW) 892 5.4.1. Dual stack ICN deployments in UE 894 The control and user plane communications in LTE, 4G mobile networks 895 are specified in 3GPP documents [TS23.203] and [TS23.401]. It is 896 important to understand that UE can be either consumer (receiving 897 content) or publisher (pushing content for other clients). The 898 protocol stack inside mobile device (UE) is complex because it has to 899 support multiple radio connectivity access to eNodeB(s). 901 Figure 5 provides a high-level description of a protocol stack, where 902 IP is defined at two layers: (1) user plane communication and (2) UDP 903 encapsulation. User plane communication takes place between Packet 904 Data Convergence Protocol (PDCP) and Application layer, whereas UDP 905 encapsulation is at GTP protocol stack. 907 The protocol interactions and impact of supporting tunneling of ICN 908 packet into IP or to support ICN natively are described in Figure 5 909 and Figure 6, respectively. 911 +--------+ +--------+ 912 | App | | CDN | 913 +--------+ +--------+ 914 |Transp. | | | | |Transp. | 915 |Converg.|.|..............|...............|............|.|Converge| 916 +--------+ | | | +--------+ | +--------+ 917 | |.|..............|...............|.| |.|.| | 918 | ICN/IP | | | | | ICN/IP | | | ICN/IP| 919 | | | | | | | | | | 920 +--------+ | +----+-----+ | +-----+-----+ | +-----+--+ | +--------+ 921 | |.|.| | |.|.| | |.|.| | | | | | 922 | PDCP | | |PDCP|GTP-U| | |GTP-U|GTP-U| | |GTP-U| | | | L2 | 923 +--------+ | +----------+ | +-----------+ | +-----+ | | | | 924 | RLC |.|.|RLC | UDP |.|.| UDP | UDP |.|.|UDP |L2|.|.| | 925 +--------+ | +----------+ | +-----------+ | +-----+ | | | | 926 | MAC |.|.| MAC| L2 |.|.| L2 | L2 |.|.| L2 | | | | | 927 +--------+ | +----------+ | +-----------+ | +--------+ | +--------+ 928 | L1 |.|.| L1 | L1 |.|.| L1 | L1 |.|.| L1 |L1|.|.| L1 | 929 +--------+ | +----+-----+ | +-----+-----+ | +-----+--+ | +--------+ 930 UE | BS(eNodeB) | SGW | PGW | 931 Uu S1U S5/S8 SGi 933 Figure 5: Dual Stack ICN Deployment in UE 935 The protocols and software stack used inside LTE capable UE support 936 both 3G and LTE software interworking and handover. Latest 3GPP 937 Rel.13 onward specification describes the use of IP and non-IP 938 protocols to establish logical/session connectivity. We intend to 939 leverage the non-IP protocol-based mechanism to deploy ICN protocol 940 stack in UE, as well as in eNodeB and mobile gateways (SGW, PGW). 942 1. Existing application layer can be modified to provide options for 943 a new ICN-based application and existing IP-based applications. 944 UE can continue to support existing IP-based applications or host 945 new applications developed to support native ICN as transport, 946 ICNoIP, or IPoICN-based transport. Application layer has the 947 option of selecting either ICN or IP transport, as well as radio 948 interface, to send and receive data traffic. 950 Our proposal is to provide an Application Programming Interface 951 (API) to the application developers so they can choose either ICN 952 or IP transport for exchanging the traffic with the network. As 953 mentioned in Section 5.2, the transport convergence layer (TCL) 954 function handles the interaction of applications with multiple 955 transport options. 957 2. The transport convergence layer helps determine the type of 958 transport (such as ICN, hICN, or IP) and type of radio interface 959 (LTE or WiFi, or both) used to send and receive traffic. 960 Application layer can make the decision to select a specific 961 transport based on preference, such as content location, content 962 type, content publisher, congestion, cost, QoS, and so on. There 963 can be an Application Programming Interface (API) to exchange 964 parameters required for transport selection. Southbound 965 interactions of Transport Convergence Layer (TCL) will be either 966 to IP or ICN at the network layer. 968 When selecting the IPoICN mode, the TCL is responsible for 969 receiving an incoming IP or HTTP packet and publishing the packet 970 to the ICN network under a suitable ICN name (that is, the hash 971 over the destination IP address for an IP packet, or the hash 972 over the FQDN of the HTTP request for an HTTP packet). In the 973 HTTP case, the TCL maintains a pending request mapping table to 974 map returning responses to the originating HTTP request. The 975 common API will provide a common 'connection' abstraction for 976 this HTTP mode of operation, returning the response over said 977 connection abstraction, akin to the TCP socket interface, while 978 implementing a reliable transport connection semantic over the 979 ICN from the UE to the receiving UE or the PGW. If the HTTP 980 protocol stack remains unchanged, therefore utilizing the TCP 981 protocol for transfer, the TCL operates in local TCP termination 982 mode, retrieving the HTTP packet through said local termination. 984 +----------------+ +-----------------+ 985 | ICN App (new) | |IP App (existing)| 986 +---------+------+ +-------+---------+ 987 | | 988 +---------+----------------+---------+ 989 | Transport Convergence Layer (new) | 990 +------+---------------------+-------+ 991 | | 992 +------+------+ +------+-------+ 993 |ICN function | | IP function | 994 | (New) | | (Existing) | 995 +------+------+ +------+-------+ 996 | | 997 +------+---------------------+-------+ 998 | PDCP (updated to support ICN) | 999 +-----------------+------------------+ 1000 | 1001 +-----------------+------------------+ 1002 | RLC (Existing) | 1003 +-----------------+------------------+ 1004 | 1005 +-----------------+------------------+ 1006 | MAC Layer (Existing) | 1007 +-----------------+------------------+ 1008 | 1009 +-----------------+------------------+ 1010 | Physical L1 (Existing) | 1011 +------------------------------------+ 1013 Figure 6: Dual Stack ICN Protocol Interactions 1015 3. ICN function (forwarder) is introduced in parallel to the 1016 existing IP layer. ICN forwarder contains functional 1017 capabilities to forward ICN packets, such as Interest packet to 1018 eNodeB or response "data packet" from eNodeB to the application. 1020 4. For the dual-stack scenario, when UE is not supporting ICN as 1021 transport, we use IP underlay to transport ICN packets. ICN 1022 function will use IP interface to send Interest and Data packets 1023 for fetching or sending data using ICN protocol function. This 1024 interface will use ICN overlay over IP using any overlay 1025 tunneling mechanism. 1027 5. To support ICN at network layer in UE, PDCP layer has to be aware 1028 of ICN capabilities and parameters. PDCP is located in the Radio 1029 Protocol Stack in the LTE Air interface, between IP (Network 1030 layer) and Radio Link Control Layer (RLC). PDCP performs the 1031 following functions [TS36.323]: 1033 1. Data transport by listening to upper layer, formatting and 1034 pushing down to Radio Link Layer (RLC) 1036 2. Header compression and decompression using Robust Header 1037 Compression (ROHC) 1039 3. Security protections such as ciphering, deciphering, and 1040 integrity protection 1042 4. Radio layer messages associated with sequencing, packet drop 1043 detection and re-transmission, and so on. 1045 6. No changes are required for lower layer such as RLC, MAC, and 1046 Physical (L1) because they are not IP aware. 1048 One key point to understand in this scenario is that ICN is deployed 1049 as an overlay on top of IP. 1051 5.4.2. Native ICN Deployments in UE 1053 We propose to implement ICN natively in UE by modifying the PDCP 1054 layer in 3GPP protocols. Figure 7 provides a high-level protocol 1055 stack description where ICN is used at the following different 1056 layers: 1058 1. User plane communication 1060 2. Transport layer 1062 User plane communication takes place between PDCP and application 1063 layer, whereas ICN transport is a substitute of GTP protocol. 1064 Removal of GTP protocol stack is a significant change in mobile 1065 architecture because GTP is used not just for routing but for 1066 mobility management functions, such as billing, mediation, and policy 1067 enforcement. 1069 If we implement ICN natively in UE, communication between UE and 1070 eNodeB will change. Also, this will avoid tunneling the user plane 1071 traffic from eNodeB to the mobile packet core (SGW, PGW) using GTP 1072 tunnel. 1074 For native ICN deployment, an application will be configured to use 1075 ICN forwarder so there is no need for Transport Convergence. Also, 1076 to support ICN at the network layer in UE, we need to modify the 1077 existing PDCP layer. PDCP layer must be aware of ICN capabilities 1078 and parameters. 1080 Native implementation will also provide opportunities to develop new 1081 use cases leveraging ICN capabilities, such as seamless mobility, UE 1082 to UE content delivery using radio network without traversing the 1083 mobile gateways, and more. 1085 +--------+ +--------+ 1086 | App | | CDN | 1087 +--------+ +--------+ 1088 |Transp. | | | | | |Transp. | 1089 |Converge|.|..............|..............|..............|.|Converge| 1090 +--------+ | | | | +--------+ 1091 | |.|..............|..............|..............|.| | 1092 | ICN/IP | | | | | | | 1093 | | | | | | | | 1094 +--------+ | +----+-----+ | +----------+ | +----------+ | | ICN/IP | 1095 | |.|.| | | | | | | | | | | | 1096 | PDCP | | |PDCP| ICN |.|.| ICN |.|.| ICN |.|.| | 1097 +--------+ | +----+ | | | | | | | | | | 1098 | RLC |.|.|RLC | | | | | | | | | | | 1099 +--------+ | +----------+ | +----------+ | +----------+ | +--------+ 1100 | MAC |.|.| MAC| L2 |.|.| L2 |.|.| L2 |.|.| L2 | 1101 +--------+ | +----------+ | +----------+ | +----------+ | +--------+ 1102 | L1 |.|.| L1 | L1 |.|.| L1 |.|.| L1 |.|.| L1 | 1103 +--------+ | +----+-----+ | +----------+ | +----------+ | +--------+ 1104 UE | BS(eNodeB) | SGW | PGW | 1105 Uu S1u S5/S8 SGi 1107 Figure 7: Native ICN Deployment in UE 1109 5.5. ICN Deployment in eNodeB 1111 eNodeB is a physical point of attachment for UE, where radio 1112 protocols are converted into IP transport protocol for dual stack/ 1113 overlay and native ICN, respectively (see Figure 6 and Figure 7). 1114 When UE performs attach procedures, it is assigned an identity either 1115 as IP or dual stack (IP and ICN), or ICN. UE can initiate data 1116 traffic using any of the following options: 1118 1. Native IP (IPv4 or IPv6) 1120 2. Native ICN 1122 3. Dual stack IP (IPv4/IPv6) or ICN 1123 UE encapsulates user data transport request into PDCP layer and sends 1124 the information on air interface to eNodeB. eNodeB receives the 1125 information and, using PDCP [TS36.323], de-encapsulates air-interface 1126 messages and converts them to forward to core mobile gateways (SGW, 1127 PGW). As shown in Figure 8, to support ICN natively in eNodeB, it is 1128 proposed to provide transport convergence layer (TCL) capabilities in 1129 eNodeB (similar to as provided in UE), which provides the following 1130 functions: 1132 1. It decides the forwarding strategy for a user data request coming 1133 from UE. The strategy can decide based on preference indicated 1134 by the application, such as congestion, cost, QoS, and so on. 1136 2. eNodeB to provide open Application Programming Interface (API) to 1137 external management systems, to provide capability to eNodeB to 1138 program the forwarding strategies. 1140 +---------------+ | 1141 | UE request | | ICN +---------+ 1142 +---> | content using |--+--- transport -->| | 1143 | |ICN protocol | | | | 1144 | +---------------+ | | | 1145 | | | | 1146 | +---------------+ | | | 1147 +-+ | | UE request | | IP |To mobile| 1148 | |---+---> | content using |--+--- transport -->| GW | 1149 +-+ | | IP protocol | | |(SGW,PGW)| 1150 UE | +---------------+ | | | 1151 | | | | 1152 | +---------------+ | | | 1153 | | UE request | | Dual stack | | 1154 +---> | content using |--+--- IP+ICN -->| | 1155 |IP/ICN protocol| | transport +---------+ 1156 +---------------+ | 1157 eNodeB S1u 1159 Figure 8: Native ICN Deployment in eNodeB 1161 3. eNodeB can be upgraded to support three different types of 1162 transport: IP, ICN, and dual stack IP+ICN towards mobile 1163 gateways, as depicted in Figure 8. It is also proposed to deploy 1164 IP and/or ICN forwarding capabilities into eNodeB, for efficient 1165 transfer of data between eNodeB and mobile gateways. Following 1166 are choices for forwarding a data request towards mobile 1167 gateways: 1169 1. Assuming eNodeB is IP enabled and UE requests IP transfer, 1170 eNodeB forwards data over IP. 1172 2. Assuming eNodeB is ICN enabled and UE requests ICN transfer, 1173 eNodeB forwards data over ICN. 1175 3. Assuming eNodeB is IP enabled and UE requests ICN, eNodeB 1176 overlays ICN on IP and forwards user plane traffic over IP. 1178 4. Assuming eNodeB is ICN enabled and UE requests IP, eNodeB 1179 overlays IP on ICN and forwards user plane traffic over ICN 1180 [IPoICN]. 1182 5.6. ICN Deployment in Packet Core (SGW, PGW) Gateways 1184 Mobile gateways---also known as Evolved Packet Core (EPC)--include 1185 SGW, PGW, which perform session management for UE from the initial 1186 attach to disconnection. When UE is powered on, it performs NAS 1187 signaling and attaches to PGW after successful authentication. PGW 1188 is an anchoring point for UE and responsible for service creations, 1189 authorization, maintenance, and so on. The Entire functionality is 1190 managed using IP address(es) for UE. 1192 To implement ICN in EPC, the following functions are proposed: 1194 1. Insert ICN attributes in session management layer as additional 1195 functionality with IP stack. Session management layer is used 1196 for performing attach procedures and assigning logical identity 1197 to user. After successful authentication by HSS, MME sends a 1198 create session request (CSR) to SGW and SGW to PGW. 1200 2. When MME sends Create Session Request message (Step 12 in 1201 [TS23.401]) to SGW or PGW, it includes a Protocol Configuration 1202 Option Information Element (PCO IE) containing UE capabilities. 1203 We can use PCO IE to carry ICN-related capabilities information 1204 from UE to PGW. This information is received from UE during the 1205 initial attach request in MME. Details of available TLV, which 1206 can be used for ICN, are given in subsequent sections. UE can 1207 support either native IP, ICN+IP, or native ICN. IP is referred 1208 to as both IPv4 and IPv6 protocols. 1210 3. For ICN+IP-capable UE, PGW assigns the UE both an IP address and 1211 ICN identity. UE selects either of the identities during the 1212 initial attach procedures and registers with the network for 1213 session management. For ICN-capable UE, it will provide only ICN 1214 attachment. For native IP-capable UE, there is no change. 1216 4. To support ICN-capable attach procedures and use ICN for user 1217 plane traffic, PGW needs to have full ICN protocol stack 1218 functionalities. Typical ICN capabilities include functions such 1219 as content store (CS), Pending Interest Table (PIT), Forwarding 1220 Information Base (FIB) capabilities, and so on. If UE requests 1221 ICN in PCO IE, then PGW registers UE with ICN names. For ICN 1222 forwarding, PGW caches content locally using CS functionality. 1224 5. PCO IE described in [TS24.008] (see Figure 10.5.136 on page 598) 1225 and [TS24.008] (see Table 10.5.154 on page 599) provide details 1226 for different fields. 1228 1. Octet 3 (configuration protocols define PDN types), which 1229 contains details about IPv4, IPv6, both or ICN. 1231 2. Any combination of Octet 4 to Z can be used to provide 1232 additional information related to ICN capability. It is most 1233 important that PCO IE parameters are matched between UE and 1234 mobile gateways (SGW, PGW) so they can be interpreted 1235 properly and the UE can attach successfully. 1237 6. Deployment of ICN functionalities in SGW and PGW should be 1238 matched with UE and eNodeB because they will exchange ICN 1239 protocols and parameters. 1241 7. Mobile gateways SGW, PGW will also need ICN forwarding and 1242 caching capability. This is especially important if CUPS is 1243 implemented. User Plane Function (UPF), comprising the SGW and 1244 PGW user plane, will be located at the edge of the network and 1245 close to the end user. ICN-enabled gateway means that this UPF 1246 would serve as a forwarder and should be capable of caching, as 1247 is the case with any other ICN-enabled node. 1249 8. The transport between PGW and CDN provider can be either IP or 1250 ICN. When UE is attached to PGW with ICN identity and 1251 communicates with an ICN-enabled CDN provider, it will use ICN 1252 primitives to fetch the data. On the other hand, for a UE 1253 attached with an ICN identity, if PGW has to communicate with an 1254 IP- enabled CDN provider, it will have to use an ICN-IP 1255 interworking gateway to perform conversion between ICN and IP 1256 primitives for data retrieval. In the case of CUPS 1257 implementation with an offload close to the edge, this 1258 interworking gateway can be collocated with the UPF at the 1259 offload site to maximize the path optimization. Further study is 1260 required to understand how this ICN-to-IP (and vice versa) 1261 interworking gateway would function. 1263 6. Security Considerations 1265 To ensure only authenticated UEs are connected to the network, LTE 1266 mobile network implements various security mechanisms. From the 1267 perspective of ICN deployment in the user plane, it needs to take 1268 care of the following security aspects: 1270 1. UE authentication and authorization 1272 2. Radio or air interface security 1274 3. Denial of service attacks on mobile gateway, services 1276 4. Content positioning either in transport or servers 1278 5. Content cache pollution attacks 1280 6. Secure naming, routing, and forwarding 1282 7. Application security 1284 Security over the LTE air interface is provided through cryptographic 1285 technique. When UE is powered up, it performs key exchange between 1286 UE's USIM and HSS/Authentication Center using NAS messages, including 1287 ciphering and integrity protections between UE and MME. Details of 1288 secure UE authentication, key exchange, ciphering, and integrity 1289 protections messages are given in the 3GPP call flow [TS23.401]. 1291 LTE is an all-IP network and uses IP transport in its mobile backhaul 1292 (between eNodeB and core network). In case of provider-owned 1293 backhaul, it may not implement security mechanisms; however, they are 1294 necessary in case it uses a shared or leased network. The native IP 1295 transport continues to leverage security mechanism such as Internet 1296 key exchange (IKE) and the IP security protocol (IPsec). More 1297 details of mobile backhaul security are provided in 3GPP network 1298 security [TS33.310] and [TS33.320]. When mobile backhaul is upgraded 1299 to support dual stack (IP+ICN) or native ICN, it is required to 1300 implement security techniques that are deployed in mobile backhaul. 1301 When ICN forwarding is enabled on mobile transport routers, we need 1302 to deploy security practices based on [RFC7476] and [RFC7927]. 1304 Some key functions supported by LTE mobile gateway (SGW, PGW) are 1305 content based billing, deep packet inspection (DPI), and lawful 1306 intercept (LI). For ICN-based user plane traffic, it is required to 1307 integrate ICN security for sessions between UE and gateway. However, 1308 in the ICN network, some of the services provided by mobile gateways 1309 mentioned above may not work because only consumers who have 1310 decryption keys can access the content. Further research in this 1311 area is needed. 1313 7. Summary 1315 In this draft, we have discussed complexities of LTE network and key 1316 dependencies for deploying ICN in user plane data transport. 1317 Different deployment options described cover aspects such as inter 1318 operability and multi-technology, which is a reality for any Service 1319 Provider. One can use LTE gateway software and ICN simulator and 1320 deploy ICN data transport in user plane as an overlay, dual stack (IP 1321 + ICN), hICN, or natively (by integrating ICN with CDN, eNodeB, SGW, 1322 PGW and transport network). Notice that, for deployment scenarios 1323 discussed above, additional study is required for lawful 1324 interception, billing/mediation, network slicing, and provisioning 1325 APIs. 1327 Mobile Edge Computing (MEC) [CHENG] provides capabilities to deploy 1328 functionalities such as Content Delivery Network (CDN) caching and 1329 mobile user plane functions (UPF) [TS23.501]. Recent research for 1330 delivering real-time video content [MPVCICN] using ICN has also been 1331 proven to be efficient [NDNRTC] and can be used towards realizing the 1332 benefits of ICN deployment in eNodeB, MEC, mobile gateways (SGW, PGW) 1333 and CDN. The key aspect for ICN is in its seamless integration in 1334 LTE and 5G networks with tangible benefits so we can optimize content 1335 delivery using simple and scalable architecture. Authors will 1336 continue to explore how ICN forwarding in MEC could be used in 1337 efficient data delivery from the mobile edge. 1339 Based on our study of control plane signaling, it is not beneficial 1340 to deploy ICN with existing protocols unless further changes are 1341 introduced in the control protocol stack itself. As mentioned in 1342 [TS23.501], 5G network architecture proposes simplification of 1343 control plane messages and can be a candidate for use of ICN. 1345 As a starting step towards ICN user plane deployment, it is proposed 1346 to incorporate protocol changes in UE, eNodeB, SGW/PGW for data 1347 transport. ICN has inherent capabilities for mobility and content 1348 caching, which can improve the efficiency of data transport for 1349 unicast and multicast delivery. Authors welcome contributions and 1350 suggestions, including those related to further validations of the 1351 principles by implementing prototype and/or proof of concept in the 1352 lab and in the production environment. 1354 8. Acknowledgements 1356 We thank all contributors, reviewers, and the chairs for the valuable 1357 time in providing comments and feedback that helped improve this 1358 draft. We specially want to mention the following members of the 1359 IRTF Information-Centric Networking Research Group (ICNRG), listed in 1360 alphabetical order: Thomas Jagodits, Luca Muscariello, David R. 1361 Oran, Akbar Rahman, Martin J. Reed, and Thomas C. Schmidt. 1363 The IRSG review was provided by Colin Perkins. 1365 9. References 1367 9.1. Normative References 1369 [TS24.008] 1370 3GPP, "Mobile radio interface Layer 3 specification; Core 1371 network protocols; Stage 3", 3GPP TS 24.008 3.20.0, 1372 December 2005, 1373 . 1375 [TS25.323] 1376 3GPP, "Packet Data Convergence Protocol (PDCP) 1377 specification", 3GPP TS 25.323 3.10.0, September 2002, 1378 . 1380 [TS29.274] 1381 3GPP, "3GPP Evolved Packet System (EPS); Evolved General 1382 Packet Radio Service (GPRS) Tunneling Protocol for Control 1383 plane (GTPv2-C); Stage 3", 3GPP TS 29.274 10.11.0, June 1384 2013, . 1386 [TS29.281] 1387 3GPP, "General Packet Radio System (GPRS) Tunneling 1388 Protocol User Plane (GTPv1-U)", 3GPP TS 29.281 10.3.0, 1389 September 2011, 1390 . 1392 [TS36.323] 1393 3GPP, "Evolved Universal Terrestrial Radio Access 1394 (E-UTRA); Packet Data Convergence Protocol (PDCP) 1395 specification", 3GPP TS 36.323 10.2.0, January 2013, 1396 . 1398 9.2. Informative References 1400 [ALM] Auge, J., Carofiglio, G., Grassi, G., Muscariello, L., 1401 Pau, G., and X. Zeng, "Anchor-Less Producer Mobility in 1402 ICN", Proceedings of the 2Nd ACM Conference on 1403 Information-Centric Networking, ACM-ICN'15, ACM DL, 1404 pp.189-190, September 2013, 1405 . 1407 [BROWER] Brower, E., Jeffress, L., Pezeshki, J., Jasani, R., and E. 1408 Ertekin, "Integrating Header Compression with IPsec", 1409 MILCOM 2006 - 2006 IEEE Military Communications 1410 conference IEEE Xplore DL, pp.1-6, October 2006, 1411 . 1413 [CCN] "Content Centric Networking", . 1415 [CHENG] Liang, C., Yu, R., and X. Zhang, "Information-centric 1416 network function virtualization over 5g mobile wireless 1417 networks", IEEE Network Journal vol. 29, number 3, pp. 1418 68-74, June 2015, 1419 . 1421 [EPCCUPS] Schmitt, P., Landais, B., and F. Yong Yang, "Control and 1422 User Plane Separation of EPC nodes (CUPS)", 3GPP The 1423 Mobile Broadband Standard, July 2017, 1424 . 1426 [GALIS] Galis, A., Makhijani, K., Yu, D., and B. Liu, "Autonomic 1427 Slice Networking", draft-galis-anima-autonomic-slice- 1428 networking-05 (work in progress), September 2018. 1430 [GRAYSON] Grayson, M., Shatzkamer, M., and S. Wainner, "Cisco Press 1431 book "IP Design for Mobile Networks"", Cisco 1432 Press Networking Technology series, June 2009, 1433 . 1436 [H2020] H2020, "The POINT Project", . 1438 [HICN] Muscariello, L., Carofiglio, G., Auge, J., and M. 1439 Papalini, "Hybrid Information-Centric Networking", draft- 1440 muscariello-intarea-hicn-01 (work in progress), December 1441 2018. 1443 [ICN5G] Ravindran, R., suthar, P., Trossen, D., and G. White, 1444 "Enabling ICN in 3GPP's 5G NextGen Core Architecture", 1445 draft-ravi-icnrg-5gc-icn-02 (work in progress), July 2018. 1447 [ICNLOWPAN] 1448 Gundogan, C., Schmidt, T., Waehlisch, M., Scherb, C., 1449 Marxer, C., and C. Tschudin, "ICN Adaptation to LowPAN 1450 Networks (ICN LoWPAN)", draft-irtf-icnrg-icnlowpan-02 1451 (work in progress), March 2019. 1453 [ICNQoS] Al-Naday, M., Bontozoglou, A., Vassilakis, G., and M. 1454 Reed, "Quality of Service in an Information-Centric 1455 Network", 2014 IEEE Global Communications Conference IEEE 1456 Xplore DL, pp. 1861-1866, December 2014, 1457 . 1459 [IPoICN] Trossen, D., Read, M., Riihijarvi, J., Georgiades, M., 1460 Fotiou, N., and G. Xylomenos, "IP over ICN - The better 1461 IP?", 2015 European Conference on Networks and 1462 Communications (EuCNC) IEEE Xplore DL, pp. 413-417, June 1463 2015, . 1465 [MBICN] Carofiglio, G., Gallo, M., Muscariello, L., and D. Perino, 1466 "Scalable mobile backhauling via information-centric 1467 networking", The 21st IEEE International Workshop on Local 1468 and Metropolitan Area Networks, Beijing, pp. 1-6, April 1469 2015, . 1471 [MECSPEC] "Mobile Edge Computing (MEC); Framework and Reference 1472 Architecture", ETSI European Telecommunication Standards 1473 Institute (ETSI) MEC specification, March 2016, 1474 . 1477 [MPVCICN] Jangam, A., Ravindran, R., Chakraborti, A., Wan, X., and 1478 G. Wang, "Realtime multi-party video conferencing service 1479 over information centric network", IEEE International 1480 Conference on Multimedia and Expo Workshops (ICMEW) Turin, 1481 Italy, pp. 1-6, June 2015, 1482 . 1484 [NDNRTC] Gusev, P., Wang, Z., Burke, J., Zhang, L., Yoneda, T., 1485 Ohnishi, R., and E. Muramoto, "Real-time Streaming Data 1486 Delivery over Named Data Networking,", IEICE Transactions 1487 on Communications vol. E99.B, pp. 974-991, May 2016, 1488 . 1490 [NGMN] Robson, J., "Data Offloading Techniques in Cellular 1491 Networks: A Survey", Next Generation Mobile Networks, LTE- 1492 Advanced Transport Provisioning, V0.0.14, October 2015, 1493 . 1496 [OFFLOAD] Rebecchi, F., Dias de Amorim, M., Conan, V., Passarella, 1497 A., Bruno, R., and M. Conti, "Data Offloading Techniques 1498 in Cellular Networks: A Survey", IEEE Communications 1499 Surveys and Tutorials, IEEE Xplore DL, vol:17, issue:2, 1500 pp.580-603, November 2014, 1501 . 1503 [OLTEANU] Olteanu, A. and P. Xiao, "Fragmentation and AES Encryption 1504 Overhead in Very High-speed Wireless LANs", Proceedings of 1505 the 2009 IEEE International Conference on Communications 1506 ICC'09, ACM DL, pp.575-579, June 2009, 1507 . 1509 [RFC4594] Babiarz, J., Chan, K., and F. Baker, "Configuration 1510 Guidelines for DiffServ Service Classes", RFC 4594, 1511 DOI 10.17487/RFC4594, August 2006, 1512 . 1514 [RFC6459] Korhonen, J., Ed., Soininen, J., Patil, B., Savolainen, 1515 T., Bajko, G., and K. Iisakkila, "IPv6 in 3rd Generation 1516 Partnership Project (3GPP) Evolved Packet System (EPS)", 1517 RFC 6459, DOI 10.17487/RFC6459, January 2012, 1518 . 1520 [RFC7476] Pentikousis, K., Ed., Ohlman, B., Corujo, D., Boggia, G., 1521 Tyson, G., Davies, E., Molinaro, A., and S. Eum, 1522 "Information-Centric Networking: Baseline Scenarios", 1523 RFC 7476, DOI 10.17487/RFC7476, March 2015, 1524 . 1526 [RFC7927] Kutscher, D., Ed., Eum, S., Pentikousis, K., Psaras, I., 1527 Corujo, D., Saucez, D., Schmidt, T., and M. Waehlisch, 1528 "Information-Centric Networking (ICN) Research 1529 Challenges", RFC 7927, DOI 10.17487/RFC7927, July 2016, 1530 . 1532 [RFC8569] Mosko, M., Solis, I., and C. Wood, "Content-Centric 1533 Networking (CCNx) Semantics", RFC 8569, 1534 DOI 10.17487/RFC8569, July 2019, 1535 . 1537 [RFC8609] Mosko, M., Solis, I., and C. Wood, "Content-Centric 1538 Networking (CCNx) Messages in TLV Format", RFC 8609, 1539 DOI 10.17487/RFC8609, July 2019, 1540 . 1542 [SDN5G] Page, J. and J. Dricot, "Software-defined networking for 1543 low-latency 5G core network", 2016 International 1544 Conference on Military Communications and Information 1545 Systems (ICMCIS) IEEE Xplore DL, pp. 1-7, May 2016, 1546 . 1548 [TLVCOMP] Mosko, M., "Header Compression for TLV-based Packets", 1549 ICNRG Buenos Aires IETF 95, April 2016, 1550 . 1553 [TS23.203] 1554 3GPP, "Policy and charging control architecture", 3GPP 1555 TS 23.203 10.9.0, September 2013, 1556 . 1558 [TS23.401] 1559 3GPP, "General Packet Radio Service (GPRS) enhancements 1560 for Evolved Universal Terrestrial Radio Access Network 1561 (E-UTRAN) access", 3GPP TS 23.401 10.10.0, March 2013, 1562 . 1564 [TS23.501] 1565 3GPP, "System Architecture for the 5G System", 3GPP 1566 TS 23.501 15.2.0, June 2018, 1567 . 1569 [TS23.714] 1570 3GPP, "Technical Specification Group Services and System 1571 Aspects: Study on control and user plane separation of EPC 1572 nodes", 3GPP TS 23.714 0.2.2, June 2016, 1573 . 1575 [TS29.060] 1576 3GPP, "General Packet Radio Service (GPRS); GPRS Tunneling 1577 Protocol (GTP) across the Gn and Gp interface", 3GPP 1578 TS 29.060 3.19.0, March 2004, 1579 . 1581 [TS33.310] 1582 3GPP, "Network Domain Security (NDS); Authentication 1583 Framework (AF)", 3GPP TS 33.310 10.7.0, December 2012, 1584 . 1586 [TS33.320] 1587 3GPP, "Security of Home Node B (HNB) / Home evolved Node B 1588 (HeNB)", 3GPP TS 33.320 10.5.0, June 2012, 1589 . 1591 Authors' Addresses 1593 Prakash Suthar 1594 Cisco Systems Inc. 1595 Rosemont, Illinois 60018 1596 USA 1598 Email: psuthar@cisco.com 1600 Milan Stolic 1601 Cisco Systems Inc. 1602 Rosemont, Illinois 60018 1603 USA 1605 Email: mistolic@cisco.com 1607 Anil Jangam (editor) 1608 Cisco Systems Inc. 1609 San Jose, California 95134 1610 USA 1612 Email: anjangam@cisco.com 1614 Dirk Trossen 1615 Huawei Technologies 1616 Riesstrasse 25 1617 Munich 80992 1618 Germany 1620 Email: dirk.trossen@huawei.com 1622 Ravishankar Ravindran 1623 Sterlite Technologies 1624 5201 Greatamerica Pkwy 1625 Santa Clara, California 95054 1626 USA 1628 Email: ravishankar.ravindran@sterlite.com