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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group D. Farinacci 3 Internet-Draft lispers.net 4 Intended status: Experimental P. Pillay-Esnault 5 Expires: March 12, 2021 Independent 6 U. Chunduri 7 Futurewei Technologies 8 September 8, 2020 10 LISP for the Mobile Network 11 draft-farinacci-lisp-mobile-network-09 13 Abstract 15 This specification describes how the LISP architecture and protocols 16 can be used in a LTE/5G mobile network to support session survivable 17 EID mobility. A recommendation is provided to SDOs on how to 18 integrate LISP into the mobile network. 20 Status of This Memo 22 This Internet-Draft is submitted in full conformance with the 23 provisions of BCP 78 and BCP 79. 25 Internet-Drafts are working documents of the Internet Engineering 26 Task Force (IETF). Note that other groups may also distribute 27 working documents as Internet-Drafts. The list of current Internet- 28 Drafts is at https://datatracker.ietf.org/drafts/current/. 30 Internet-Drafts are draft documents valid for a maximum of six months 31 and may be updated, replaced, or obsoleted by other documents at any 32 time. It is inappropriate to use Internet-Drafts as reference 33 material or to cite them other than as "work in progress." 35 This Internet-Draft will expire on March 12, 2021. 37 Copyright Notice 39 Copyright (c) 2020 IETF Trust and the persons identified as the 40 document authors. All rights reserved. 42 This document is subject to BCP 78 and the IETF Trust's Legal 43 Provisions Relating to IETF Documents 44 (https://trustee.ietf.org/license-info) in effect on the date of 45 publication of this document. Please review these documents 46 carefully, as they describe your rights and restrictions with respect 47 to this document. Code Components extracted from this document must 48 include Simplified BSD License text as described in Section 4.e of 49 the Trust Legal Provisions and are provided without warranty as 50 described in the Simplified BSD License. 52 Table of Contents 54 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 55 2. Definition of Terms . . . . . . . . . . . . . . . . . . . . . 4 56 3. Design Overview . . . . . . . . . . . . . . . . . . . . . . . 6 57 4. Addressing and Routing . . . . . . . . . . . . . . . . . . . 13 58 5. gNB/eNodeB LISP Functionality . . . . . . . . . . . . . . . . 13 59 6. UPF/pGW LISP Functionality . . . . . . . . . . . . . . . . . 14 60 7. Compatible Data-Plane using GTP . . . . . . . . . . . . . . . 14 61 8. Roaming and Packet Loss . . . . . . . . . . . . . . . . . . . 15 62 9. Mobile Network LISP Mapping System . . . . . . . . . . . . . 15 63 10. LISP Over the 5G N3/N6/N9 Interfaces . . . . . . . . . . . . 15 64 11. Multicast Considerations . . . . . . . . . . . . . . . . . . 17 65 12. Security Considerations . . . . . . . . . . . . . . . . . . . 18 66 13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 67 14. SDO Recommendations . . . . . . . . . . . . . . . . . . . . . 18 68 15. References . . . . . . . . . . . . . . . . . . . . . . . . . 18 69 15.1. Normative References . . . . . . . . . . . . . . . . . . 18 70 15.2. Informative References . . . . . . . . . . . . . . . . . 19 71 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 22 72 Appendix B. Document Change Log . . . . . . . . . . . . . . . . 23 73 B.1. Changes to draft-farinacci-lisp-mobile-network-09 . . . . 23 74 B.2. Changes to draft-farinacci-lisp-mobile-network-08 . . . . 23 75 B.3. Changes to draft-farinacci-lisp-mobile-network-07 . . . . 23 76 B.4. Changes to draft-farinacci-lisp-mobile-network-06 . . . . 23 77 B.5. Changes to draft-farinacci-lisp-mobile-network-05 . . . . 23 78 B.6. Changes to draft-farinacci-lisp-mobile-network-04 . . . . 23 79 B.7. Changes to draft-farinacci-lisp-mobile-network-03 . . . . 23 80 B.8. Changes to draft-farinacci-lisp-mobile-network-02 . . . . 24 81 B.9. Changes to draft-farinacci-lisp-mobile-network-01 . . . . 24 82 B.10. Changes to draft-farinacci-lisp-mobile-network-00 . . . . 24 83 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24 85 1. Introduction 87 The LISP architecture and protocols [RFC6830] introduces two new 88 numbering spaces, Endpoint Identifiers (EIDs) and Routing Locators 89 (RLOCs) which provide an architecture to build overlays on top of the 90 underlying Internet. Mapping EIDs to RLOC-sets is accomplished with 91 a Mapping Database System. By using a level of indirection for 92 routing and addressing, separating an address identifier from its 93 location can allow flexible and scalable mobility. By assigning EIDs 94 to mobile devices and RLOCs to the network nodes that support such 95 mobile devices, LISP can provide seamless mobility. 97 For a reading audience unfamiliar with LISP, a brief tutorial level 98 document is available at [I-D.ietf-lisp-introduction]. 100 This specification will describe how LISP can be used to provide 101 layer-3 mobility within and across an LTE [LTE401-3GPP] [LTE402-3GPP] 102 and 5G [ARCH5G-3GPP] [PROC5G-3GPP] mobile network. 104 The following are the design requirements: 106 1. Layer-3 address mobility is provided within a mobile network RAN 107 supported by a UPF/pGW region (intra-UPF/pGW) as well as across 108 UPF/pGW regions (inter-UPF/pGW). 110 2. UE nodes can get layer-3 address mobility when roaming off the 111 mobile network to support Fixed Mobile Convergence [FMC]. 113 3. Transport layer session survivability exists while roaming 114 within, across, and off of the mobile network. 116 4. No address management is required when UEs roam. EID addresses 117 are assigned to UEs at subscription time. EIDs can be reassigned 118 when UE ownership changes. 120 5. The design will make efficient use of radio resources thereby not 121 adding extra headers to packets that traverse the RAN. 123 6. The design can support IPv4 unicast and multicast packet delivery 124 and will support IPv6 unicast and multicast packet delivery. 126 7. The design will allow use of both the GTP [GTPv1-3GPP] 127 [GTPv2-3GPP] and LISP [I-D.ietf-lisp-rfc6830bis] data-planes 128 while using the LISP control-plane and mapping system. 130 8. The design can be used for either 4G/LTE and 5G mobile networks 131 and may be able to support interworking between the different 132 mobile networks. 134 9. The LISP architecture provides a level of indirection for routing 135 and addressing. From a mobile operator's perspective, these 136 mechanisms provide advantages and efficiencies for the URLLC, 137 FMC, and mMTC use cases. See Section 2 for definitions and 138 references of these use cases. 140 The goal of this specification is take advantage of LISP's non- 141 disruptive incremental deployment benefits. This can be achieved by 142 changing the fewest number of components in the mobile network. The 143 proposal suggests adding LISP functionality only to gNB/eNodeB and 144 UPF/pGW nodes. There are no hardware or software changes to the UE 145 devices or the RF-based RAN to realize this architecture. The LISP 146 mapping database system is deployed as an addition to the mobile 147 network and does not require any coordination with existing 148 management and provisioning systems. 150 Similar ID Oriented Networking (ION) mechanisms for the 5G 151 [ARCH5G-3GPP] [PROC5G-3GPP] mobile network are also being considered 152 in other standards organizations such as ETSI [ETSI-NGP] and ITU 153 [ITU-IMT2020]. The NGMN Alliance describes Locator/ID separation an 154 enabler to meet Key Performance Indicator Requirements [NGMN]. 156 2. Definition of Terms 158 xTR: Is a LISP node in the network that runs the LISP control-plane 159 and data-plane protocols according to [I-D.ietf-lisp-rfc6830bis] 160 and [I-D.ietf-lisp-rfc6833bis]. A formal definition of an xTR can 161 be found in [RFC6830]. In this specification, a LISP xTR is a 162 node that runs the LISP control-plane with the GTP data-plane. 164 EID: Is an Endpoint Identifier. EIDs are assigned to UEs and other 165 Internet nodes in LISP sites. A formal definition of an EID can 166 be found in [RFC6830]. 168 UE EID: A UE can be assigned an IPv4 and/or an IPv6 address either 169 statically, or dynamically as is the procedure in the mobile 170 network today. These IP addresses are known as LISP EIDs and are 171 registered to the LISP mapping system. These EIDs are used as the 172 source address in packets that the UE originates. 174 RLOC: Is an Routing Locator. RLOCs are assigned to gNB/eNodeBs and 175 UPF/pGWs and other LISP xTRs in LISP sites. A formal definition 176 of an RLOC can be found in [RFC6830]. 178 Mapping System: Is the LISP mapping database system that stores EID- 179 to-RLOC mappings. The mapping system is centralized for use and 180 distributed to scale and secure deployment. LISP Map-Register 181 messages are used to publish mappings and LISP Map-Requests 182 messages are used to lookup mappings. LISP Map-Reply messages are 183 used to return mappings. EID-records are used as lookup keys, and 184 RLOC-records are returned as a result of the lookup. Details can 185 be found in [RFC6833]. 187 LISP Control-Plane: In this specification, a LISP xTR runs the LISP 188 control-plane which originates, consumes, and processes Map- 189 Request, Map-Register, Map-Reply, and Map-Notify messages. 191 RAN: Radio Access Network where UE nodes connect to gNB/eNodeB nodes 192 via radios to get access to the Internet. 194 EPC: Evolved Packet Core [EPS-3GPP] system is the part of the mobile 195 network that allows the RAN to connect to a data packet network. 196 The EPC is a term used for the 4G/LTE mobile network. 198 NGC: Next Generation Core [EPS-3GPP] system is the part of the 5G 199 mobile network that allows the RAN to connect to a data packet 200 network. The NGC is roughly equivalent to the 4G EPC. 202 GTP: GTP [GTPv1-3GPP] [GTPv2-3GPP] is the UDP tunneling mechanism 203 used in the LTE/4G and 5G mobile network. 205 UE: User Equipment as defined by [GPRS-3GPP] which is typically a 206 mobile phone. The UE is connected to the network across the RAN 207 to gNB/eNodeB nodes. 209 eNodeB: Is the device defined by [GPRS-3GPP] which borders the RAN 210 and connects UEs to the EPC in a 4G/LTE mobile network. The 211 eNodeB nodes are termination point for a GTP tunnel and are LISP 212 xTRs. The equivalent term in the 5G mobile network is "(R)AN" and 213 "5G-NR", or simply "gNB". In this document, the two terms are 214 used interchangeably. 216 pGW: Is the PDN-Gateway as defined by [GPRS-3GPP] connects the EPC 217 in a 4G/LTE mobile network to the Internet. The pGW nodes are 218 termination point for a GTP tunnel and is a LISP xTR. The 219 equivalent user/data-plane term in the 5G mobile network is the 220 "UPF", which also has the capability to chain network functions. 221 In this document, the two terms are used interchangeably to mean 222 the border point from the EPC/NGC to the Internet. 224 URLLC: Ultra-Reliable and Low-Latency provided by the 5G mobile 225 network for the shortest path between UEs [NGMN]. 227 FMC: Fixed Mobile Convergence [FMC] is a term used that allows a UE 228 device to move to and from the mobile network. By assigning a 229 fixed EID to a UE device, LISP supports transport layer continuity 230 between the mobile network and a fixed infrastructure such as a 231 WiFi network. 233 mMTC: Massive Machine-Type Services [mMTC] is a term used to refer 234 to using the mobile network for large-scale deployment of Internet 235 of Things (IoT) applications. 237 3. Design Overview 239 LISP will provide layer-3 address mobility based on the procedures in 240 [I-D.ietf-lisp-eid-mobility] where the EID and RLOCs are not co- 241 located. In this design, the EID is assigned to the UE device and 242 the RLOC(s) are assigned to gNB/eNodeB nodes. So any packets going 243 to a UE are always encapsulated to the gNB/eNodeB that associates 244 with the UE. For data flow from the UE to any EIDs (or destinations 245 to non-LISP sites) that are outside of the NGC/EPC, use the RLOCs of 246 the UPF/pGW nodes so the UPF/pGW can send packets into the Internet 247 core (unencapsulated). 249 The following procedures are used to incorporate LISP in the NGC/EPC: 251 o UEs are assigned EIDs. They usually never change. They identify 252 the mobile device and are used for transport connections. If 253 privacy for EIDs is desired, refer to details in 254 [I-D.ietf-lisp-eid-anonymity]. 256 o gNB/eNodeB nodes are LISP xTRs. They have GTP, and optionally 257 LISP, tunnels to the UPF/pGW nodes. The gNB/eNodeB is the RLOC 258 for all EIDs assigned to UE devices that are attached to the gNB/ 259 eNodeB. 261 o UPF/pGW nodes are LISP xTRs. They have GTP, and optionally LISP, 262 tunnels to the gNB/eNodeB nodes. The UPF/pGW is the RLOC for all 263 traffic destined for the Internet. 265 o The LISP mapping system runs in the NGC/EPC. It maps EIDs to 266 RLOC-sets. 268 o Traffic from a UE to UE within a UPF/pGW region can be 269 encapsulated from gNB/eNodeB to another gNB/eNodeB or via the UPF/ 270 pGW, acting as an RTR [RFC6830], to provide data-plane policy. 272 o Traffic from a UE to UE across a UPF/pGW region have these options 273 for data flow: 275 1. Encapsulation by a gNB/eNodeB in one region to a gNB/eNodeB in 276 another region. 278 2. Encapsulation by a gNB/eNodeB in one region to a UPF/pGW in 279 the same region and then the UPF/pGW reencapsulates to a gNB/ 280 eNodeB in another region. 282 3. Encapsulation by a gNB/eNodeB in one region to a UPF/pGW in 283 another region and then the UPF/pGW reencapsulates to a gNB/ 284 eNodeB in its same region 286 4. Encapsulation by the gNB/eNodeB to a LISP xTR outside of the 287 mobile network. An xTR outside of the mobile network could be 288 a router in a data-center, a router at the edge of a WAN at a 289 remote branch, or a WiFi access-point, and even a gNB/eNodeB 290 in another carrier's mobile network. All these deployment 291 options are to be considered for future architectures. 293 o Note when encapsulation happens between a gNB/eNodeB and a UPF/ 294 pGW, GTP is used as the data-plane and when encapsulation between 295 two gNB/eNodeBs occur, LISP can be used as the data-plane when 296 there is no X2 interface [X2-3GPP] between the gNB/eNodeB nodes. 298 o The UPF/pGW nodes register their RLOCs for a default EID-prefix to 299 the LISP mapping system. This is done so gNB/eNodeB nodes can 300 find UPF/pGW nodes to encapsulate to. 302 o The gNB/eNodeB nodes register EIDs to the mapping system for the 303 UE nodes. The registration occurs when gNB/eNodeB nodes discover 304 the layer-3 addresses of the UEs that connect to them. The gNB/ 305 eNodeB nodes register multiple RLOCs associated with the EIDs to 306 get multi-homing and path diversity benefits from the NGC/EPC 307 network. 309 o When a UE moves off a gNB/eNodeB, the gNB/eNodeB node deregisters 310 itself as an RLOC for the EID associated with the UE. 312 o Optionally, and for further study for future architectures, the 313 gNB/eNodeB or UPF/pGW could encapsulate to an xTR that is outside 314 of the NGC/EPC network. They could encapsulate to a LISP CPE 315 router at a branch office, a LISP top-of-rack router in a data 316 center, a LISP wifi access-point, LISP border routers at a hub 317 site, and even a LISP router running in a VM or container on a 318 server. 320 The following diagram illustrates the LTE mobile network topology and 321 structure [LTE401-3GPP] [LTE402-3GPP]: 323 (--------------------------------------------) 324 ( ) 325 ( Internet ) 326 ( ) 327 (--------------------------------------------) 328 | | 329 | | 330 (---------|---------) (---------|---------) 331 ( UPF-pGW ) ( UPF-pGW ) 332 ( ) ( ) 333 ( NGC/EPC ) ( NGC/EPC ) 334 ( ) ( ) 335 ( gNB-eNB gNB-eNB ) ( gNB-eNB gNB-eNB ) 336 (---/--\-----/--\---) (---/--\-----/--\---) 337 / \ / \ / \ / \ 338 / \ / \ / \ / \ 339 / \ / \ 340 / RAN \ / RAN \ 341 / \ / \ 342 ( UE UE UE ) ( UE UE UE ) 344 LTE/5G Mobile Network Architecture 346 The following diagram illustrates how LISP is used on the mobile 347 network: 349 (1) IPv6 EIDs are assigned to UEs. 350 (2) RLOCs assigned to gNB/eNodeB nodes are [a1,a2], [b1,b2], [c1,c2], [d1,d2] 351 on their uplink interfaces. 352 (3) RLOCs assigned to UPF/pGW nodes are [p1,p2], [p3,p4]. 353 (4) RLOCs can be IPv4 or IPv6 addresses or mixed RLOC-sets. 355 (--------------------------------------------) 356 ( ) 357 ( Internet ) 358 ( ) 359 (--------------------------------------------) 360 | | 361 | | 362 (---------|---------) (---------|---------) 363 ( UPF-pGW ) ( UPF-pGW ) 364 ( p1 p2 ) ( p3 p4 ) 365 ( ) ( ) 366 ( NGC/EPC ) ( NGC/EPC ) 367 ( ) ( ) 368 ( a1 a2 b1 b2 ) ( c1 c2 d1 d2 ) 369 ( gNB-eNB gNB-eNB ) ( gNB-eNB gNB-eNB ) 370 (---/--\-----/--\---) (---/--\-----/--\---) 371 / \ / \ / \ / \ 372 / \ / \ / \ / \ 373 / \ / \ 374 / RAN \ / RAN \ 375 / \ / \ 376 ( UE UE UE ) ( UE UE UE ) 377 EIDs: a::1 b::1 c::1 x::1 y::1 z::1 379 Mobile Network with EID/RLOC Assignment 381 The following table lists the EID-to-RLOC entries that reside in the LISP 382 Mapping System when the above UEs are are attached to the 4 gNB/eNodeBs: 384 EID-Record RLOC-Record Commentary Footnote 385 0::/0 [p1,p2,p3 p4] gNB/eNodeBs encap to p1-p4 for Internet (1) 386 destinations which are non-EIDs 388 a::1/128 [a1,a2] UPF/pGWs load-split traffic to [a1,a2] for (2) 389 UE a::1 and it can move to [b1,b2] 391 b::1/128 [a1,a2] gNB/eNodeB tracks both UEs a::1 and b::1, (3) 392 it can do local routing between the UEs 394 c::1/128 [b1,b2] UE c::1 can roam to [c1,c2] or [d1,d2], (4) 395 may use UPF/pGW [p1,p2] after move 397 x::1/128 [c1,c2] UE x::1 can talk directly to UE y::1, (5) 398 gNB/eNodeBs encap to each other 400 y::1/128 [d1,d2] UE can talk to Internet when [d1,d2], (6) 401 encap to UPF/pGW [p3,p4] or use backup [p1,p2] 403 z::1/128 [d1,d2] UE z::1 can talk to a::1 directly (7) 404 where [d1,d2] encaps to [a1,a2] 406 (1) For packets that flow from UE nodes to destinations that are not 407 in LISP sites, the gNB/eNodeB node use one of the RLOCs p1, p2, p3, 408 or p4 as the destination address in the outer encapsulated header. 409 Encapsulated packets are then routed by the NGC/EPC core to the UPF/ 410 pGW nodes. In turn, the UPF/pGW nodes, then route packets into the 411 Internet core. 413 (2) Packets that arrive to UPF/pGW nodes from the Internet destined 414 to UE nodes are encapsulated to one of the gNB/eNodeB RLOCs a1, a2, 415 b1, b2. When UE, with EID a::1 is attached to the leftmost gNB/ 416 eNodeB, the EID a::1 is registered to the mapping system with RLOCs 417 a1 and a2. When UE with EID c::1 is attached to the rightmost gNB/ 418 eNodeB (in the left region), the EID c::1 is registered to the 419 mapping system with RLOCs b1 and b2. 421 (3) If UE with EID a::1 and UE with EID b::1 are attached to the same 422 gNB/eNodeB node, the gNB/eNodeB node tracks what radio interface to 423 use to route packets from one UE to the other. 425 (4) If UE with EID c::1 roams away from gNB/eNodeB with RLOCs b1 and 426 b2, to the gNB/eNodeB with RLOCs c1 and c2 (in the rightmost region), 427 packets destined toward the Internet, can use any UPF/pGW. Any 428 packets that flow back from the Internet can use any UPF/pGW. In 429 either case, the UPF/pGW is informed by the mapping system that the 430 UE with EID c::1 has new RLOCs and should now encapsulate to either 431 RLOC c1 or c2. 433 (5) When UE with EID x::1 is attached to gNB/eNodeB with RLOCs c1 and 434 c2 and UE with EID y::1 is attached to gNB/eNodeB with RLOCs d1 and 435 d2, they can talk directly, on the shortest path to each gNB/eNodeB, 436 when each encapsulate packets to each other's RLOCs. 438 (6) When packets from UE with EID y::1 are destined for the Internet, 439 the gNB/eNodeB with RLOCs d1 and d2 that the UE is attached to can 440 use any exit UPF/pGWs RLOCs p1, p2, p3, or p4. 442 (7) UE with EID z::1 can talk directory to UE with EID a::1 by each 443 gNB/eNodeB they are attached to encapsulsates to each other's RLOCs. 444 In case (5), the two gNB/eNodeB's were in the same region. In this 445 case, the gNB/eNodeBs are in different regions. 447 The following abbreviated diagram shows a topology that illustrates 448 how a UE roams with LISP across UPF/pGW regions: 450 (--------------------------------------------) 451 ( ) 452 ( Internet ) 453 ( ) 454 (--------------------------------------------) 455 | | 456 | | 457 (---------|---------) (---------|---------) 458 ( UPF-pGW ) ( UPF-pGW ) 459 ( p1 p2 ) ( p3 p4 ) 460 ( ) ( ) 461 ( NGC/EPC ) ( NGC/EPC ) 462 ( ) ( ) 463 ( a1 a2 b1 b2 ) ( c1 c2 d1 d2 ) 464 ( gNB-eNB gNB-eNB ) ( gNB-eNB gNB-eNB ) 465 (---/--\-----/--\---) (---/--\-----/--\---) 466 / \ / \ / \ / \ 467 / \ / \ / \ / \ 468 / \ / \ 469 / RAN \ / RAN \ 470 / \ / \ 471 ( UE ------------------------------> UE ) 472 a::1 a::1 474 UE EID Mobility 476 The contents of the LISP mapping database before UE moves: 478 EID-Record RLOC-Record Commentary 479 0::/0 [p1,p2,p3,p4] gNB/eNodeB [a1,a2] encaps to p1-p4 for Internet 480 destinations when a::1 on gNB/eNodeB [a1,a2] 482 a::1/128 [a1,a2] Before UE moves to other UPF/pGW region 484 The contents of the LISP mapping database after UE moves: 486 EID-Record RLOC-Record Commentary 487 0::/0 [p1,p2,p3,p4] gNB/eNodeB [d1,d2] encaps to p1-p4 for Internet 488 destinations when a::1 moves to gNB/eNodeB 489 [d1,d2] 491 a::1/128 [d1,d2] After UE moves to new UPF/pGW region 492 4. Addressing and Routing 494 UE based EID addresses will be IPv6 addresses. It will be determined 495 at a future time what length the IPv6 prefix will be to cover all UEs 496 in a mobile network. This coarse IPv6 prefix is called an EID-prefix 497 where more-specific EID-prefixes will be allocated out of it for each 498 UPF/pGW node. Each UPF/pGW node is responsible for advertising the 499 more-specific EID-prefix into the Internet routing system so they can 500 attract packets from non-EIDs nodes to UE EIDs. 502 An RLOC address will either be an IPv4 or IPv6 address depending on 503 the support for single or dual-stack address-family in the NGC/EPC 504 network. An RLOC-set in the mapping system can have a mixed address- 505 family locator set. There is no requirement for the NGC/EPC to 506 change to support one address-family or the other. And there is no 507 requirement for the NGC/EPC network to support IPv4 multicast or IPv6 508 multicast. The LISP overlay will support both. 510 The only requirement for RLOC addresses is that they are routable in 511 the NGC/EPC and the Internet core network. 513 The requirements of the LISP and GTP data-plane overlay is to support 514 a layer-3 overlay network only. There is no architectural 515 requirement to support layer-2 overlays. However, operators may want 516 to provide a layer-2 LAN service over their mobile network. Details 517 about how LISP supports layer-2 overlays can be found in 518 [I-D.ietf-lisp-eid-mobility]. 520 5. gNB/eNodeB LISP Functionality 522 The gNB/eNodeB node runs as a LISP xTR for control-plane 523 functionality and runs GTP for data-plane functionality. Optionally, 524 the LISP data-plane can be used to establish dynamic tunnels from one 525 gNB/eNodeB node to another gNB/eNodeB node. 527 The gNB/eNodeB LISP xTR will follow the procedures of 528 [I-D.ietf-lisp-eid-mobility] to discover UE based EIDs, track them by 529 monitoring liveness, registering them when appear, and deregistering 530 them when they move away. Since the gNB/eNodeB node is an xTR, it is 531 acting as a layer-3 router and the GTP tunnel from the gNB/eNodeB 532 node to the UPF/pGW node is realizing a layer-3 overlay. This will 533 provide scaling benefits since broadcast and link-local multicast 534 packets won't have to travel across the NGC/EPC to the UPF/pGW node. 536 A day in the life of a UE originated packet: 538 1. The UE node originates an IP packet over the RAN. 540 2. The gNB/eNodeB receives the packet, extracts the source address 541 from the packet, learns the UE based EID, stores its RAN location 542 locally and registers the EID to the mapping system. 544 3. The gNB/eNodeB extracts the destination address, looks up the 545 address in the mapping system. The lookup returns the RLOC of a 546 UPF/pGW node if the destination is not an EID or an RLOC gNB/ 547 eNodeB node if the destination is a UE based EID. 549 4. The gNB/eNodeB node encapsulates the packet to the RLOC using GTP 550 or optionally the LISP data-plane. 552 It is important to note that in [I-D.ietf-lisp-eid-mobility], EID 553 discovery occurs when a LISP xTR receives an IP or ARP/ND packet. 554 However, if there are other methods to discover the EID of a device, 555 like in UE call setup, the learning and registration referenced in 556 Paragraph 2 can happen before any packet is sent. 558 6. UPF/pGW LISP Functionality 560 The UPF/pGW node runs as a LISP xTR for control-plane functionality 561 and runs GTP for data-plane functionality. Optionally, the LISP 562 data-plane can be used to establish dynamic tunnels from one UPF/pGW 563 node to another UPF/pGW or gNB/eNodeB node. 565 The UPF/pGW LISP xTR does not follow the EID mobility procedures of 566 [I-D.ietf-lisp-eid-mobility] since it is not responsible for 567 discovering UE based EIDs. A UPF/pGW LISP xTR simply follows the 568 procedures of a PxTR in [RFC6830] and for interworking to non-EID 569 sites in [RFC6832]. 571 A day in the life of a UPF/pGW received packet: 573 1. The UPF/pGW node receives a IP packet from the Internet core. 575 2. The UPF/pGW node extracts the destination address from the packet 576 and looks it up in the LISP mapping system. The lookup returns 577 an RLOC of a gNB/eNodeB node. Optionally, the RLOC could be 578 another UPF/pGW node. 580 3. The UPF/pGW node encapsulates the packet to the RLOC using GTP or 581 optionally the LISP data-plane. 583 7. Compatible Data-Plane using GTP 585 Since GTP is a UDP based encapsulating tunnel protocol, it has the 586 same benefits as LISP encapsulation. At this time, there appears to 587 be no urgent need to not continue to use GTP for tunnels between a 588 gNB/eNodeB nodes and between a gNB/eNodeB node and a UPF/pGW node. 590 There are differences between GTP tunneling and LISP tunneling. GTP 591 tunnels are setup at call initiation time. LISP tunnels are 592 dynamically encapsulating, used on demand, and don't need setup or 593 teardown. The two tunneling mechanisms are a hard state versus soft 594 state tradeoff. 596 This specification recommends for early phases of deployment, to use 597 GTP as the data-plane so a transition for it to use the LISP control- 598 plane can be achieved more easily. At later phases, the LISP data- 599 plane may be considered so a more dynamic way of using tunnels can be 600 achieved to support URLLC. 602 This specification recommends the use of procedures from 603 [I-D.ietf-lisp-eid-mobility] and NOT the use of LISP-MN 604 [I-D.ietf-lisp-mn]. Using LISP-MN states that a LISP xTR reside on 605 the mobile UE. This is to be avoided so extra encapsulation header 606 overhead is NOT sent on the RAN. The LISP data-plane or control- 607 plane will not run on the UE. 609 8. Roaming and Packet Loss 611 Using LISP for the data-plane has some advantages in terms of 612 providing near-zero packet loss. In the current mobile network, 613 packets are queued on the gNB/eNodeB node the UE is roaming to or 614 rerouted on the gNB/eNodeB node the UE has left. In the LISP 615 architecture, packets can be sent to multiple "roamed-from" and 616 "roamed-to" nodes while the UE is moving or is off the RAN. See 617 mechanisms in [I-D.ietf-lisp-predictive-rlocs] for details. 619 9. Mobile Network LISP Mapping System 621 The LISP mapping system stores and maintains EID-to-RLOC mappings. 622 There are two mapping database transport systems that are available 623 for scale, LISP-ALT [RFC6836] and LISP-DDT [RFC8111]. The mapping 624 system will store EIDs assigned to UE nodes and the associated RLOCs 625 assigned to gNB/eNodeB nodes and UPF/pGW nodes. The RLOC addresses 626 are routable addresses by the NGC/EPC network. 628 This specification recommends the use of LISP-DDT. 630 10. LISP Over the 5G N3/N6/N9 Interfaces 632 So far in this specification we have described how LISP runs on the 633 gNB and UPF nodes in the mobile network. In the 5G architecture 634 [ARCH5G-3GPP] definition, some key components are Access and Mobility 635 Management Function (AMF) and the Session Management Function (SMF). 636 These two components provide control plane functionality to off-load 637 session anchoring by distributing state and packet flow among 638 multiple nodes in the NGC. These functions can be deployed in Branch 639 Point Uplink Classifier (BP/ULCL) in data-plane nodes. 641 Here is an illustration where a B/ULCL-UPF node would appear in the 642 mobile network: 644 (--------------------------------------------) 645 ( Internet ) 646 +-> (--------------------------------------------) 647 | | 648 N6 | 649 | (---------|---------) 650 +-> ( UPF ) <-+ 651 NGC ( [p1,p2] ) | 652 ( ) N9 653 +-> ( BP/ULCL ) | 654 | ( UPF [p3,p4] ) <-+ 655 N3 ( ) 656 | ( [a1] [a2] ) 657 +-> ( gNB gNB ) 658 (---/--\-----/--\---) 659 / \ / \ 660 / \ 661 / RAN \ 662 / \ 663 ( UE UE UE ) 664 a::1 a::2 a::3 666 The BP/ULCL-UPF node is configured as an LISP RTR and uses the 667 Traffic Engineering features of LISP specified in [I-D.ietf-lisp-te]. 668 In LISP-TE an Explicit Locator Path (ELP) can be stored in the RLOC- 669 record for any given EID thereby allowing packet flow from a UE to 670 the Internet to traverse through the BP/UCLC-UPF node. A UE 671 originated packet is encapsulated by the gNB to the BP/ULCL-UPF which 672 decapsulates and reencapsulates to the UPF at the Internet border. 673 This allows LISP to run over the 5G N3 and N9 interface with one 674 mapping entry. And if the ELP contained an xTR outside of the mobile 675 network, LISP could also run over the N6 interface. 677 The contents of the LISP mapping database: 679 EID-Record RLOC-Record Commentary 680 0::/0 [ELP{a1,p3,p1}, 4 RLOC-records, 2 with paths through the BP-UPF 681 ELP{a1,p4,p2}, and 2 directly to the border UPF from UEs 682 p1, p2] connected to gNB with RLOC a1 684 a::1/128 [a1,a2] The UPF or BP-UPF can encap directly for UE with 685 EID a::1 to either gNB with optimized latency 687 a::2/128 [ELP{p1,p3,a2}, The UPF can encap to either RLOC p3 or p4 to 688 ELP{p1,p4,a2}] forward traffic through the BP-UPF on its way 689 toward gNB with RLOC a1 691 a::3/128 [ELP{p1,p3,a2}, The UPF can encap to the BP-UPF or directly 692 a2] to gNB with RLOC a2 to reach UE with EID a::3 694 11. Multicast Considerations 696 Since the mobile network runs the LISP control-plane, and the mapping 697 system is available to support EIDs for unicast packet flow, it can 698 also support multicast packet flow. Support for multicast can be 699 provided by the LISP/GTP overlay with no changes to the NGC/EPC 700 network. 702 Multicast (S-EID,G) entries can be stored and maintained in the same 703 mapping database that is used to store UE based EIDs. Both Internet 704 connected nodes, as well as UE nodes, can source multicast packets. 705 The protocol procedures from [I-D.ietf-lisp-signal-free-multicast] 706 are followed to make multicast delivery available. Both multicast 707 packet flow and UE mobility can occur at the same time. 709 A day in the life of a 1-to-many multicast packet: 711 1. A UE node joins an (S,G) multicast flow by using IGMPv2 or 712 IGMPv3. 714 2. The gNB/eNodeB node records which UE on the RAN should get 715 packets sourced by S and destined for group G. 717 3. The gNB/eNodeB node registers the (S,G) entry to the mapping 718 system with its RLOC according to the receiver site procedures in 719 [I-D.ietf-lisp-signal-free-multicast]. The gNB/eNodeB does this 720 to show interest in joining the multicast flow. 722 4. When other UE nodes join the same (S,G), their associated gNB/ 723 eNodeB nodes will follow the procedures in steps 1 through 3. 725 5. The (S,G) entry stored in the mapping database has an RLOC-set 726 which contains a replication list of all the gNB/eNodeB RLOCs 727 that registered. 729 6. A multicast packet from source S to destination group G arrives 730 at the UPF/pGW. The UPF/pGW node looks up (S,G), gets returned 731 the replication list of all joined gNB/eNodeB nodes and 732 replicates the multicast packet by encapsulating the packet to 733 each of them. 735 7. Each gNB/eNodeB node decapsulates the packet and delivers the 736 multicast packet to one or more IGMP-joined UEs on the RAN. 738 12. Security Considerations 740 For control-plane authentication and authorization procedures, this 741 specification recommends the mechanisms in 742 [I-D.ietf-lisp-rfc6833bis], LISP-SEC [I-D.ietf-lisp-sec] AND LISP- 743 ECDSA [I-D.farinacci-lisp-ecdsa-auth]. 745 For data-plane privacy procedures, this specification recommends the 746 mechanisms in [RFC8061] When the LISP data-plane is used. otherwise, 747 the NGC/EPC must provide data-plane encryption support. 749 13. IANA Considerations 751 There are no specific requests for IANA. 753 14. SDO Recommendations 755 The authors request other Standards Development Organizations to 756 consider LISP as a technology for device mobility. It is recommended 757 to start with this specification as a basis for design and develop 758 more deployment details in the appropriate Standards Organizations. 759 The authors are willing to facilitate this activity. 761 15. References 763 15.1. Normative References 765 [RFC1700] Reynolds, J. and J. Postel, "Assigned Numbers", RFC 1700, 766 DOI 10.17487/RFC1700, October 1994, 767 . 769 [RFC6830] Farinacci, D., Fuller, V., Meyer, D., and D. Lewis, "The 770 Locator/ID Separation Protocol (LISP)", RFC 6830, 771 DOI 10.17487/RFC6830, January 2013, 772 . 774 [RFC6832] Lewis, D., Meyer, D., Farinacci, D., and V. Fuller, 775 "Interworking between Locator/ID Separation Protocol 776 (LISP) and Non-LISP Sites", RFC 6832, 777 DOI 10.17487/RFC6832, January 2013, 778 . 780 [RFC6833] Fuller, V. and D. Farinacci, "Locator/ID Separation 781 Protocol (LISP) Map-Server Interface", RFC 6833, 782 DOI 10.17487/RFC6833, January 2013, 783 . 785 [RFC6836] Fuller, V., Farinacci, D., Meyer, D., and D. Lewis, 786 "Locator/ID Separation Protocol Alternative Logical 787 Topology (LISP+ALT)", RFC 6836, DOI 10.17487/RFC6836, 788 January 2013, . 790 [RFC8060] Farinacci, D., Meyer, D., and J. Snijders, "LISP Canonical 791 Address Format (LCAF)", RFC 8060, DOI 10.17487/RFC8060, 792 February 2017, . 794 [RFC8061] Farinacci, D. and B. Weis, "Locator/ID Separation Protocol 795 (LISP) Data-Plane Confidentiality", RFC 8061, 796 DOI 10.17487/RFC8061, February 2017, 797 . 799 [RFC8111] Fuller, V., Lewis, D., Ermagan, V., Jain, A., and A. 800 Smirnov, "Locator/ID Separation Protocol Delegated 801 Database Tree (LISP-DDT)", RFC 8111, DOI 10.17487/RFC8111, 802 May 2017, . 804 15.2. Informative References 806 [ARCH5G-3GPP] 807 "System Architecture for the 5G System", TS.23.501 808 https://portal.3gpp.org/desktopmodules/Specifications/ 809 SpecificationDetails.aspx?specificationId=3144, December 810 2016. 812 [EPS-3GPP] 813 "Non-Access-Stratum (NAS) Protocol for Evolved Packet 814 System (EPS); Stage 3", TS.23.501 815 https://portal.3gpp.org/desktopmodules/specifications/ 816 specificationdetails.aspx?specificationid=1072, December 817 2017. 819 [ETSI-NGP] 820 "NGP Evolved Architecture for mobility using Identity 821 Oriented Networks", NGP-004, version 0.0.3 822 https://portal.etsi.org/webapp/WorkProgram/ 823 Report_WorkItem.asp?WKI_ID=50531, May 2017. 825 [FMC] "FIXED MOBILE CONVERGENCE", 826 https://www.ipv6.com/mobile/fixed-mobile-convergence/, 827 November 2006. 829 [GPRS-3GPP] 830 "General Packet Radio Service (GPRS) for Evolved Universal 831 Terrestrial Radio Access Network (E-UTRAN) Access", 832 TS23.401 Release 8 833 https://portal.3gpp.org/desktopmodules/specifications/ 834 specificationdetails.aspx?specificationid=849, January 835 2015. 837 [GTPv1-3GPP] 838 "General Packet Radio System (GPRS) Tunnelling Protocol 839 User Plane (GTPv1-U)", TS.29.281 840 https://portal.3gpp.org/desktopmodules/Specifications/ 841 SpecificationDetails.aspx?specificationId=1699, January 842 2015. 844 [GTPv2-3GPP] 845 "3GPP Evolved Packet System (EPS); Evolved General Packet 846 Radio Service (GPRS) Tunnelling Protocol for Control plane 847 (GTPv2-C); Stage 3", TS.29.274 848 https://portal.3gpp.org/desktopmodules/Specifications/ 849 SpecificationDetails.aspx?specificationId=1692, January 850 2015. 852 [I-D.farinacci-lisp-ecdsa-auth] 853 Farinacci, D. and E. Nordmark, "LISP Control-Plane ECDSA 854 Authentication and Authorization", draft-farinacci-lisp- 855 ecdsa-auth-03 (work in progress), September 2018. 857 [I-D.ietf-lisp-eid-anonymity] 858 Farinacci, D., Pillay-Esnault, P., and W. Haddad, "LISP 859 EID Anonymity", draft-ietf-lisp-eid-anonymity-08 (work in 860 progress), April 2020. 862 [I-D.ietf-lisp-eid-mobility] 863 Portoles-Comeras, M., Ashtaputre, V., Moreno, V., Maino, 864 F., and D. Farinacci, "LISP L2/L3 EID Mobility Using a 865 Unified Control Plane", draft-ietf-lisp-eid-mobility-06 866 (work in progress), May 2020. 868 [I-D.ietf-lisp-introduction] 869 Cabellos-Aparicio, A. and D. Saucez, "An Architectural 870 Introduction to the Locator/ID Separation Protocol 871 (LISP)", draft-ietf-lisp-introduction-13 (work in 872 progress), April 2015. 874 [I-D.ietf-lisp-mn] 875 Farinacci, D., Lewis, D., Meyer, D., and C. White, "LISP 876 Mobile Node", draft-ietf-lisp-mn-08 (work in progress), 877 August 2020. 879 [I-D.ietf-lisp-predictive-rlocs] 880 Farinacci, D. and P. Pillay-Esnault, "LISP Predictive 881 RLOCs", draft-ietf-lisp-predictive-rlocs-06 (work in 882 progress), May 2020. 884 [I-D.ietf-lisp-rfc6830bis] 885 Farinacci, D., Fuller, V., Meyer, D., Lewis, D., and A. 886 Cabellos-Aparicio, "The Locator/ID Separation Protocol 887 (LISP)", draft-ietf-lisp-rfc6830bis-33 (work in progress), 888 July 2020. 890 [I-D.ietf-lisp-rfc6833bis] 891 Farinacci, D., Maino, F., Fuller, V., and A. Cabellos- 892 Aparicio, "Locator/ID Separation Protocol (LISP) Control- 893 Plane", draft-ietf-lisp-rfc6833bis-28 (work in progress), 894 July 2020. 896 [I-D.ietf-lisp-sec] 897 Maino, F., Ermagan, V., Cabellos-Aparicio, A., and D. 898 Saucez, "LISP-Security (LISP-SEC)", draft-ietf-lisp-sec-21 899 (work in progress), July 2020. 901 [I-D.ietf-lisp-signal-free-multicast] 902 Moreno, V. and D. Farinacci, "Signal-Free LISP Multicast", 903 draft-ietf-lisp-signal-free-multicast-09 (work in 904 progress), March 2018. 906 [I-D.ietf-lisp-te] 907 Farinacci, D., Kowal, M., and P. Lahiri, "LISP Traffic 908 Engineering Use-Cases", draft-ietf-lisp-te-06 (work in 909 progress), April 2020. 911 [ITU-IMT2020] 912 "Focus Group on IMT-2020", 913 https://www.itu.int/dms_pubrec/itu-r/rec/m/R-REC- 914 M.687-2-199702-I!!PDF-E.pdf. 916 [LTE401-3GPP] 917 "General Packet Radio Service (GPRS) enhancements for 918 Evolved Universal Terrestrial Radio Access Network 919 (E-UTRAN) access", TS.23.401 920 https://portal.3gpp.org/desktopmodules/Specifications/ 921 SpecificationDetails.aspx?specificationId=849, January 922 2015. 924 [LTE402-3GPP] 925 "Architecture enhancements for non-3GPP accesses", 926 TS.23.402 927 https://portal.3gpp.org/desktopmodules/Specifications/ 928 SpecificationDetails.aspx?specificationId=850, January 929 2015. 931 [mMTC] "NGMN KPIs and Deployment Scenarios for Consideration for 932 IMT2020", https://www.ngmn.org/uploads/media/151204_NGMN_ 933 KPIs_and_Deployment_Scenarios_for_Consideration_for_IMT_20 934 20_-_LS_Annex_V1_approved.pdf, December 2015. 936 [NGMN] "5G End-to-End Architecture Framework", NGMN 937 https://www.ngmn.org/uploads/ 938 media/170511_NGMN_E2EArchFramework_v0.6.5.pdf, March 2016. 940 [PROC5G-3GPP] 941 "Procedures for the 5G System", TS.23.502 942 https://portal.3gpp.org/desktopmodules/Specifications/ 943 SpecificationDetails.aspx?specificationId=3145, December 944 2016. 946 [X2-3GPP] "Evolved Universal Terrestrial Radio Access Network 947 (E-UTRAN); X2 Application Protocol (X2AP)", TS.36.423 948 https://portal.3gpp.org/desktopmodules/Specifications/ 949 SpecificationDetails.aspx?specificationId=2452, June 2017. 951 Appendix A. Acknowledgments 953 The authors would like to thank Gerry Foster and Peter Ashwood Smith 954 for their expertise with 3GPP mobile networks and for their early 955 review and contributions. The authors would also like to thank Fabio 956 Maino, Malcolm Smith, and Marc Portoles for their expertise in both 957 5G and LISP as well as for their early review comments. 959 The authors would like to give a special thank you to Ryosuke 960 Kurebayashi from NTT Docomo and Kalyani Bogineni from Verizon for 961 their operational and practical commentary. 963 Appendix B. Document Change Log 965 B.1. Changes to draft-farinacci-lisp-mobile-network-09 967 o Posted September 2020. 969 o Update references and document timer. 971 B.2. Changes to draft-farinacci-lisp-mobile-network-08 973 o Posted March 2020. 975 o Change author affliations. 977 B.3. Changes to draft-farinacci-lisp-mobile-network-07 979 o Posted March 2020. 981 o Update references and document timer. 983 B.4. Changes to draft-farinacci-lisp-mobile-network-06 985 o Posted September 2019. 987 o Update references and document timer. 989 B.5. Changes to draft-farinacci-lisp-mobile-network-05 991 o Posted March 2019. 993 o Update references and document timer. 995 B.6. Changes to draft-farinacci-lisp-mobile-network-04 997 o Posted September 2018. 999 o Update document timer. 1001 B.7. Changes to draft-farinacci-lisp-mobile-network-03 1003 o Posted March 2018. 1005 o Make the spec more 5G user-friendly. That is, the design has 1006 always worked for either 4G or 5G but we make it more clear about 1007 5G by using some basic 5G node terminlogy. 1009 o Add a section how LISP can work on the N3, N6, and N9 5G spec 1010 interfaces. 1012 o Describe how LISP-TE can allow BP-UPF offload functionality. 1014 B.8. Changes to draft-farinacci-lisp-mobile-network-02 1016 o Posted mid September 2017. 1018 o Editorial fixes from draft -01. 1020 B.9. Changes to draft-farinacci-lisp-mobile-network-01 1022 o Posted September 2017. 1024 o Explain each EID case illustrated in the "Mobile Network with EID/ 1025 RLOC Assignment" diagram. 1027 o Make a reference to mMTC as a 3GPP use-case for 5G. 1029 o Add to the requirements section how mobile operators believe that 1030 using Locator/ID separation mechanisms provide for more efficient 1031 mobile netwowks. 1033 o Indicate that L2-overlays is not recommended by this specification 1034 as the LISP mobile network architeture but how operators may want 1035 to deploy a layer-2 overlay service. 1037 B.10. Changes to draft-farinacci-lisp-mobile-network-00 1039 o Initial draft posted August 2017. 1041 Authors' Addresses 1043 Dino Farinacci 1044 lispers.net 1045 San Jose, CA 1046 USA 1048 Email: farinacci@gmail.com 1050 Padma Pillay-Esnault 1051 Independent 1052 Santa Clara, CA 1053 USA 1055 Email: padma.ietf@gmail.com 1056 Uma Chunduri 1057 Futurewei Technologies 1058 Santa Clara, CA 1059 USA 1061 Email: umac.ietf@gmail.com