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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: September 13, 2020 Independent 6 U. Chunduri 7 Futurewei Technologies 8 March 12, 2020 10 LISP for the Mobile Network 11 draft-farinacci-lisp-mobile-network-08 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 September 13, 2020. 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-08 . . . . 23 74 B.2. Changes to draft-farinacci-lisp-mobile-network-07 . . . . 23 75 B.3. Changes to draft-farinacci-lisp-mobile-network-06 . . . . 23 76 B.4. Changes to draft-farinacci-lisp-mobile-network-05 . . . . 23 77 B.5. Changes to draft-farinacci-lisp-mobile-network-04 . . . . 23 78 B.6. Changes to draft-farinacci-lisp-mobile-network-03 . . . . 23 79 B.7. Changes to draft-farinacci-lisp-mobile-network-02 . . . . 24 80 B.8. Changes to draft-farinacci-lisp-mobile-network-01 . . . . 24 81 B.9. Changes to draft-farinacci-lisp-mobile-network-00 . . . . 24 82 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24 84 1. Introduction 86 The LISP architecture and protocols [RFC6830] introduces two new 87 numbering spaces, Endpoint Identifiers (EIDs) and Routing Locators 88 (RLOCs) which provide an architecture to build overlays on top of the 89 underlying Internet. Mapping EIDs to RLOC-sets is accomplished with 90 a Mapping Database System. By using a level of indirection for 91 routing and addressing, separating an address identifier from its 92 location can allow flexible and scalable mobility. By assigning EIDs 93 to mobile devices and RLOCs to the network nodes that support such 94 mobile devices, LISP can provide seamless mobility. 96 For a reading audience unfamiliar with LISP, a brief tutorial level 97 document is available at [I-D.ietf-lisp-introduction]. 99 This specification will describe how LISP can be used to provide 100 layer-3 mobility within and across an LTE [LTE401-3GPP] [LTE402-3GPP] 101 and 5G [ARCH5G-3GPP] [PROC5G-3GPP] mobile network. 103 The following are the design requirements: 105 1. Layer-3 address mobility is provided within a mobile network RAN 106 supported by a UPF/pGW region (intra-UPF/pGW) as well as across 107 UPF/pGW regions (inter-UPF/pGW). 109 2. UE nodes can get layer-3 address mobility when roaming off the 110 mobile network to support Fixed Mobile Convergence [FMC]. 112 3. Transport layer session survivability exists while roaming 113 within, across, and off of the mobile network. 115 4. No address management is required when UEs roam. EID addresses 116 are assigned to UEs at subscription time. EIDs can be reassigned 117 when UE ownership changes. 119 5. The design will make efficient use of radio resources thereby not 120 adding extra headers to packets that traverse the RAN. 122 6. The design can support IPv4 unicast and multicast packet delivery 123 and will support IPv6 unicast and multicast packet delivery. 125 7. The design will allow use of both the GTP [GTPv1-3GPP] 126 [GTPv2-3GPP] and LISP [I-D.ietf-lisp-rfc6830bis] data-planes 127 while using the LISP control-plane and mapping system. 129 8. The design can be used for either 4G/LTE and 5G mobile networks 130 and may be able to support interworking between the different 131 mobile networks. 133 9. The LISP architecture provides a level of indirection for routing 134 and addressing. From a mobile operator's perspective, these 135 mechanisms provide advantages and efficiencies for the URLLC, 136 FMC, and mMTC use cases. See Section 2 for definitions and 137 references of these use cases. 139 The goal of this specification is take advantage of LISP's non- 140 disruptive incremental deployment benefits. This can be achieved by 141 changing the fewest number of components in the mobile network. The 142 proposal suggests adding LISP functionality only to gNB/eNodeB and 143 UPF/pGW nodes. There are no hardware or software changes to the UE 144 devices or the RF-based RAN to realize this architecture. The LISP 145 mapping database system is deployed as an addition to the mobile 146 network and does not require any coordination with existing 147 management and provisioning systems. 149 Similar ID Oriented Networking (ION) mechanisms for the 5G 150 [ARCH5G-3GPP] [PROC5G-3GPP] mobile network are also being considered 151 in other standards organizations such as ETSI [ETSI-NGP] and ITU 152 [ITU-IMT2020]. The NGMN Alliance describes Locator/ID separation an 153 enabler to meet Key Performance Indicator Requirements [NGMN]. 155 2. Definition of Terms 157 xTR: Is a LISP node in the network that runs the LISP control-plane 158 and data-plane protocols according to [I-D.ietf-lisp-rfc6830bis] 159 and [I-D.ietf-lisp-rfc6833bis]. A formal definition of an xTR can 160 be found in [RFC6830]. In this specification, a LISP xTR is a 161 node that runs the LISP control-plane with the GTP data-plane. 163 EID: Is an Endpoint Identifier. EIDs are assigned to UEs and other 164 Internet nodes in LISP sites. A formal definition of an EID can 165 be found in [RFC6830]. 167 UE EID: A UE can be assigned an IPv4 and/or an IPv6 address either 168 statically, or dynamically as is the procedure in the mobile 169 network today. These IP addresses are known as LISP EIDs and are 170 registered to the LISP mapping system. These EIDs are used as the 171 source address in packets that the UE originates. 173 RLOC: Is an Routing Locator. RLOCs are assigned to gNB/eNodeBs and 174 UPF/pGWs and other LISP xTRs in LISP sites. A formal definition 175 of an RLOC can be found in [RFC6830]. 177 Mapping System: Is the LISP mapping database system that stores EID- 178 to-RLOC mappings. The mapping system is centralized for use and 179 distributed to scale and secure deployment. LISP Map-Register 180 messages are used to publish mappings and LISP Map-Requests 181 messages are used to lookup mappings. LISP Map-Reply messages are 182 used to return mappings. EID-records are used as lookup keys, and 183 RLOC-records are returned as a result of the lookup. Details can 184 be found in [RFC6833]. 186 LISP Control-Plane: In this specification, a LISP xTR runs the LISP 187 control-plane which originates, consumes, and processes Map- 188 Request, Map-Register, Map-Reply, and Map-Notify messages. 190 RAN: Radio Access Network where UE nodes connect to gNB/eNodeB nodes 191 via radios to get access to the Internet. 193 EPC: Evolved Packet Core [EPS-3GPP] system is the part of the mobile 194 network that allows the RAN to connect to a data packet network. 195 The EPC is a term used for the 4G/LTE mobile network. 197 NGC: Next Generation Core [EPS-3GPP] system is the part of the 5G 198 mobile network that allows the RAN to connect to a data packet 199 network. The NGC is roughly equivalent to the 4G EPC. 201 GTP: GTP [GTPv1-3GPP] [GTPv2-3GPP] is the UDP tunneling mechanism 202 used in the LTE/4G and 5G mobile network. 204 UE: User Equipment as defined by [GPRS-3GPP] which is typically a 205 mobile phone. The UE is connected to the network across the RAN 206 to gNB/eNodeB nodes. 208 eNodeB: Is the device defined by [GPRS-3GPP] which borders the RAN 209 and connects UEs to the EPC in a 4G/LTE mobile network. The 210 eNodeB nodes are termination point for a GTP tunnel and are LISP 211 xTRs. The equivalent term in the 5G mobile network is "(R)AN" and 212 "5G-NR", or simply "gNB". In this document, the two terms are 213 used interchangeably. 215 pGW: Is the PDN-Gateway as defined by [GPRS-3GPP] connects the EPC 216 in a 4G/LTE mobile network to the Internet. The pGW nodes are 217 termination point for a GTP tunnel and is a LISP xTR. The 218 equivalent user/data-plane term in the 5G mobile network is the 219 "UPF", which also has the capability to chain network functions. 220 In this document, the two terms are used interchangeably to mean 221 the border point from the EPC/NGC to the Internet. 223 URLLC: Ultra-Reliable and Low-Latency provided by the 5G mobile 224 network for the shortest path between UEs [NGMN]. 226 FMC: Fixed Mobile Convergence [FMC] is a term used that allows a UE 227 device to move to and from the mobile network. By assigning a 228 fixed EID to a UE device, LISP supports transport layer continuity 229 between the mobile network and a fixed infrastructure such as a 230 WiFi network. 232 mMTC: Massive Machine-Type Services [mMTC] is a term used to refer 233 to using the mobile network for large-scale deployment of Internet 234 of Things (IoT) applications. 236 3. Design Overview 238 LISP will provide layer-3 address mobility based on the procedures in 239 [I-D.ietf-lisp-eid-mobility] where the EID and RLOCs are not co- 240 located. In this design, the EID is assigned to the UE device and 241 the RLOC(s) are assigned to gNB/eNodeB nodes. So any packets going 242 to a UE are always encapsulated to the gNB/eNodeB that associates 243 with the UE. For data flow from the UE to any EIDs (or destinations 244 to non-LISP sites) that are outside of the NGC/EPC, use the RLOCs of 245 the UPF/pGW nodes so the UPF/pGW can send packets into the Internet 246 core (unencapsulated). 248 The following procedures are used to incorporate LISP in the NGC/EPC: 250 o UEs are assigned EIDs. They usually never change. They identify 251 the mobile device and are used for transport connections. If 252 privacy for EIDs is desired, refer to details in 253 [I-D.ietf-lisp-eid-anonymity]. 255 o gNB/eNodeB nodes are LISP xTRs. They have GTP, and optionally 256 LISP, tunnels to the UPF/pGW nodes. The gNB/eNodeB is the RLOC 257 for all EIDs assigned to UE devices that are attached to the gNB/ 258 eNodeB. 260 o UPF/pGW nodes are LISP xTRs. They have GTP, and optionally LISP, 261 tunnels to the gNB/eNodeB nodes. The UPF/pGW is the RLOC for all 262 traffic destined for the Internet. 264 o The LISP mapping system runs in the NGC/EPC. It maps EIDs to 265 RLOC-sets. 267 o Traffic from a UE to UE within a UPF/pGW region can be 268 encapsulated from gNB/eNodeB to another gNB/eNodeB or via the UPF/ 269 pGW, acting as an RTR [RFC6830], to provide data-plane policy. 271 o Traffic from a UE to UE across a UPF/pGW region have these options 272 for data flow: 274 1. Encapsulation by a gNB/eNodeB in one region to a gNB/eNodeB in 275 another region. 277 2. Encapsulation by a gNB/eNodeB in one region to a UPF/pGW in 278 the same region and then the UPF/pGW reencapsulates to a gNB/ 279 eNodeB in another region. 281 3. Encapsulation by a gNB/eNodeB in one region to a UPF/pGW in 282 another region and then the UPF/pGW reencapsulates to a gNB/ 283 eNodeB in its same region 285 4. Encapsulation by the gNB/eNodeB to a LISP xTR outside of the 286 mobile network. An xTR outside of the mobile network could be 287 a router in a data-center, a router at the edge of a WAN at a 288 remote branch, or a WiFi access-point, and even a gNB/eNodeB 289 in another carrier's mobile network. All these deployment 290 options are to be considered for future architectures. 292 o Note when encapsulation happens between a gNB/eNodeB and a UPF/ 293 pGW, GTP is used as the data-plane and when encapsulation between 294 two gNB/eNodeBs occur, LISP can be used as the data-plane when 295 there is no X2 interface [X2-3GPP] between the gNB/eNodeB nodes. 297 o The UPF/pGW nodes register their RLOCs for a default EID-prefix to 298 the LISP mapping system. This is done so gNB/eNodeB nodes can 299 find UPF/pGW nodes to encapsulate to. 301 o The gNB/eNodeB nodes register EIDs to the mapping system for the 302 UE nodes. The registration occurs when gNB/eNodeB nodes discover 303 the layer-3 addresses of the UEs that connect to them. The gNB/ 304 eNodeB nodes register multiple RLOCs associated with the EIDs to 305 get multi-homing and path diversity benefits from the NGC/EPC 306 network. 308 o When a UE moves off a gNB/eNodeB, the gNB/eNodeB node deregisters 309 itself as an RLOC for the EID associated with the UE. 311 o Optionally, and for further study for future architectures, the 312 gNB/eNodeB or UPF/pGW could encapsulate to an xTR that is outside 313 of the NGC/EPC network. They could encapsulate to a LISP CPE 314 router at a branch office, a LISP top-of-rack router in a data 315 center, a LISP wifi access-point, LISP border routers at a hub 316 site, and even a LISP router running in a VM or container on a 317 server. 319 The following diagram illustrates the LTE mobile network topology and 320 structure [LTE401-3GPP] [LTE402-3GPP]: 322 (--------------------------------------------) 323 ( ) 324 ( Internet ) 325 ( ) 326 (--------------------------------------------) 327 | | 328 | | 329 (---------|---------) (---------|---------) 330 ( UPF-pGW ) ( UPF-pGW ) 331 ( ) ( ) 332 ( NGC/EPC ) ( NGC/EPC ) 333 ( ) ( ) 334 ( gNB-eNB gNB-eNB ) ( gNB-eNB gNB-eNB ) 335 (---/--\-----/--\---) (---/--\-----/--\---) 336 / \ / \ / \ / \ 337 / \ / \ / \ / \ 338 / \ / \ 339 / RAN \ / RAN \ 340 / \ / \ 341 ( UE UE UE ) ( UE UE UE ) 343 LTE/5G Mobile Network Architecture 345 The following diagram illustrates how LISP is used on the mobile 346 network: 348 (1) IPv6 EIDs are assigned to UEs. 349 (2) RLOCs assigned to gNB/eNodeB nodes are [a1,a2], [b1,b2], [c1,c2], [d1,d2] 350 on their uplink interfaces. 351 (3) RLOCs assigned to UPF/pGW nodes are [p1,p2], [p3,p4]. 352 (4) RLOCs can be IPv4 or IPv6 addresses or mixed RLOC-sets. 354 (--------------------------------------------) 355 ( ) 356 ( Internet ) 357 ( ) 358 (--------------------------------------------) 359 | | 360 | | 361 (---------|---------) (---------|---------) 362 ( UPF-pGW ) ( UPF-pGW ) 363 ( p1 p2 ) ( p3 p4 ) 364 ( ) ( ) 365 ( NGC/EPC ) ( NGC/EPC ) 366 ( ) ( ) 367 ( a1 a2 b1 b2 ) ( c1 c2 d1 d2 ) 368 ( gNB-eNB gNB-eNB ) ( gNB-eNB gNB-eNB ) 369 (---/--\-----/--\---) (---/--\-----/--\---) 370 / \ / \ / \ / \ 371 / \ / \ / \ / \ 372 / \ / \ 373 / RAN \ / RAN \ 374 / \ / \ 375 ( UE UE UE ) ( UE UE UE ) 376 EIDs: a::1 b::1 c::1 x::1 y::1 z::1 378 Mobile Network with EID/RLOC Assignment 380 The following table lists the EID-to-RLOC entries that reside in the LISP 381 Mapping System when the above UEs are are attached to the 4 gNB/eNodeBs: 383 EID-Record RLOC-Record Commentary Footnote 384 0::/0 [p1,p2,p3 p4] gNB/eNodeBs encap to p1-p4 for Internet (1) 385 destinations which are non-EIDs 387 a::1/128 [a1,a2] UPF/pGWs load-split traffic to [a1,a2] for (2) 388 UE a::1 and it can move to [b1,b2] 390 b::1/128 [a1,a2] gNB/eNodeB tracks both UEs a::1 and b::1, (3) 391 it can do local routing between the UEs 393 c::1/128 [b1,b2] UE c::1 can roam to [c1,c2] or [d1,d2], (4) 394 may use UPF/pGW [p1,p2] after move 396 x::1/128 [c1,c2] UE x::1 can talk directly to UE y::1, (5) 397 gNB/eNodeBs encap to each other 399 y::1/128 [d1,d2] UE can talk to Internet when [d1,d2], (6) 400 encap to UPF/pGW [p3,p4] or use backup [p1,p2] 402 z::1/128 [d1,d2] UE z::1 can talk to a::1 directly (7) 403 where [d1,d2] encaps to [a1,a2] 405 (1) For packets that flow from UE nodes to destinations that are not 406 in LISP sites, the gNB/eNodeB node use one of the RLOCs p1, p2, p3, 407 or p4 as the destination address in the outer encapsulated header. 408 Encapsulated packets are then routed by the NGC/EPC core to the UPF/ 409 pGW nodes. In turn, the UPF/pGW nodes, then route packets into the 410 Internet core. 412 (2) Packets that arrive to UPF/pGW nodes from the Internet destined 413 to UE nodes are encapsulated to one of the gNB/eNodeB RLOCs a1, a2, 414 b1, b2. When UE, with EID a::1 is attached to the leftmost gNB/ 415 eNodeB, the EID a::1 is registered to the mapping system with RLOCs 416 a1 and a2. When UE with EID c::1 is attached to the rightmost gNB/ 417 eNodeB (in the left region), the EID c::1 is registered to the 418 mapping system with RLOCs b1 and b2. 420 (3) If UE with EID a::1 and UE with EID b::1 are attached to the same 421 gNB/eNodeB node, the gNB/eNodeB node tracks what radio interface to 422 use to route packets from one UE to the other. 424 (4) If UE with EID c::1 roams away from gNB/eNodeB with RLOCs b1 and 425 b2, to the gNB/eNodeB with RLOCs c1 and c2 (in the rightmost region), 426 packets destined toward the Internet, can use any UPF/pGW. Any 427 packets that flow back from the Internet can use any UPF/pGW. In 428 either case, the UPF/pGW is informed by the mapping system that the 429 UE with EID c::1 has new RLOCs and should now encapsulate to either 430 RLOC c1 or c2. 432 (5) When UE with EID x::1 is attached to gNB/eNodeB with RLOCs c1 and 433 c2 and UE with EID y::1 is attached to gNB/eNodeB with RLOCs d1 and 434 d2, they can talk directly, on the shortest path to each gNB/eNodeB, 435 when each encapsulate packets to each other's RLOCs. 437 (6) When packets from UE with EID y::1 are destined for the Internet, 438 the gNB/eNodeB with RLOCs d1 and d2 that the UE is attached to can 439 use any exit UPF/pGWs RLOCs p1, p2, p3, or p4. 441 (7) UE with EID z::1 can talk directory to UE with EID a::1 by each 442 gNB/eNodeB they are attached to encapsulsates to each other's RLOCs. 443 In case (5), the two gNB/eNodeB's were in the same region. In this 444 case, the gNB/eNodeBs are in different regions. 446 The following abbreviated diagram shows a topology that illustrates 447 how a UE roams with LISP across UPF/pGW regions: 449 (--------------------------------------------) 450 ( ) 451 ( Internet ) 452 ( ) 453 (--------------------------------------------) 454 | | 455 | | 456 (---------|---------) (---------|---------) 457 ( UPF-pGW ) ( UPF-pGW ) 458 ( p1 p2 ) ( p3 p4 ) 459 ( ) ( ) 460 ( NGC/EPC ) ( NGC/EPC ) 461 ( ) ( ) 462 ( a1 a2 b1 b2 ) ( c1 c2 d1 d2 ) 463 ( gNB-eNB gNB-eNB ) ( gNB-eNB gNB-eNB ) 464 (---/--\-----/--\---) (---/--\-----/--\---) 465 / \ / \ / \ / \ 466 / \ / \ / \ / \ 467 / \ / \ 468 / RAN \ / RAN \ 469 / \ / \ 470 ( UE ------------------------------> UE ) 471 a::1 a::1 473 UE EID Mobility 475 The contents of the LISP mapping database before UE moves: 477 EID-Record RLOC-Record Commentary 478 0::/0 [p1,p2,p3,p4] gNB/eNodeB [a1,a2] encaps to p1-p4 for Internet 479 destinations when a::1 on gNB/eNodeB [a1,a2] 481 a::1/128 [a1,a2] Before UE moves to other UPF/pGW region 483 The contents of the LISP mapping database after UE moves: 485 EID-Record RLOC-Record Commentary 486 0::/0 [p1,p2,p3,p4] gNB/eNodeB [d1,d2] encaps to p1-p4 for Internet 487 destinations when a::1 moves to gNB/eNodeB 488 [d1,d2] 490 a::1/128 [d1,d2] After UE moves to new UPF/pGW region 491 4. Addressing and Routing 493 UE based EID addresses will be IPv6 addresses. It will be determined 494 at a future time what length the IPv6 prefix will be to cover all UEs 495 in a mobile network. This coarse IPv6 prefix is called an EID-prefix 496 where more-specific EID-prefixes will be allocated out of it for each 497 UPF/pGW node. Each UPF/pGW node is responsible for advertising the 498 more-specific EID-prefix into the Internet routing system so they can 499 attract packets from non-EIDs nodes to UE EIDs. 501 An RLOC address will either be an IPv4 or IPv6 address depending on 502 the support for single or dual-stack address-family in the NGC/EPC 503 network. An RLOC-set in the mapping system can have a mixed address- 504 family locator set. There is no requirement for the NGC/EPC to 505 change to support one address-family or the other. And there is no 506 requirement for the NGC/EPC network to support IPv4 multicast or IPv6 507 multicast. The LISP overlay will support both. 509 The only requirement for RLOC addresses is that they are routable in 510 the NGC/EPC and the Internet core network. 512 The requirements of the LISP and GTP data-plane overlay is to support 513 a layer-3 overlay network only. There is no architectural 514 requirement to support layer-2 overlays. However, operators may want 515 to provide a layer-2 LAN service over their mobile network. Details 516 about how LISP supports layer-2 overlays can be found in 517 [I-D.ietf-lisp-eid-mobility]. 519 5. gNB/eNodeB LISP Functionality 521 The gNB/eNodeB node runs as a LISP xTR for control-plane 522 functionality and runs GTP for data-plane functionality. Optionally, 523 the LISP data-plane can be used to establish dynamic tunnels from one 524 gNB/eNodeB node to another gNB/eNodeB node. 526 The gNB/eNodeB LISP xTR will follow the procedures of 527 [I-D.ietf-lisp-eid-mobility] to discover UE based EIDs, track them by 528 monitoring liveness, registering them when appear, and deregistering 529 them when they move away. Since the gNB/eNodeB node is an xTR, it is 530 acting as a layer-3 router and the GTP tunnel from the gNB/eNodeB 531 node to the UPF/pGW node is realizing a layer-3 overlay. This will 532 provide scaling benefits since broadcast and link-local multicast 533 packets won't have to travel across the NGC/EPC to the UPF/pGW node. 535 A day in the life of a UE originated packet: 537 1. The UE node originates an IP packet over the RAN. 539 2. The gNB/eNodeB receives the packet, extracts the source address 540 from the packet, learns the UE based EID, stores its RAN location 541 locally and registers the EID to the mapping system. 543 3. The gNB/eNodeB extracts the destination address, looks up the 544 address in the mapping system. The lookup returns the RLOC of a 545 UPF/pGW node if the destination is not an EID or an RLOC gNB/ 546 eNodeB node if the destination is a UE based EID. 548 4. The gNB/eNodeB node encapsulates the packet to the RLOC using GTP 549 or optionally the LISP data-plane. 551 It is important to note that in [I-D.ietf-lisp-eid-mobility], EID 552 discovery occurs when a LISP xTR receives an IP or ARP/ND packet. 553 However, if there are other methods to discover the EID of a device, 554 like in UE call setup, the learning and registration referenced in 555 Paragraph 2 can happen before any packet is sent. 557 6. UPF/pGW LISP Functionality 559 The UPF/pGW node runs as a LISP xTR for control-plane functionality 560 and runs GTP for data-plane functionality. Optionally, the LISP 561 data-plane can be used to establish dynamic tunnels from one UPF/pGW 562 node to another UPF/pGW or gNB/eNodeB node. 564 The UPF/pGW LISP xTR does not follow the EID mobility procedures of 565 [I-D.ietf-lisp-eid-mobility] since it is not responsible for 566 discovering UE based EIDs. A UPF/pGW LISP xTR simply follows the 567 procedures of a PxTR in [RFC6830] and for interworking to non-EID 568 sites in [RFC6832]. 570 A day in the life of a UPF/pGW received packet: 572 1. The UPF/pGW node receives a IP packet from the Internet core. 574 2. The UPF/pGW node extracts the destination address from the packet 575 and looks it up in the LISP mapping system. The lookup returns 576 an RLOC of a gNB/eNodeB node. Optionally, the RLOC could be 577 another UPF/pGW node. 579 3. The UPF/pGW node encapsulates the packet to the RLOC using GTP or 580 optionally the LISP data-plane. 582 7. Compatible Data-Plane using GTP 584 Since GTP is a UDP based encapsulating tunnel protocol, it has the 585 same benefits as LISP encapsulation. At this time, there appears to 586 be no urgent need to not continue to use GTP for tunnels between a 587 gNB/eNodeB nodes and between a gNB/eNodeB node and a UPF/pGW node. 589 There are differences between GTP tunneling and LISP tunneling. GTP 590 tunnels are setup at call initiation time. LISP tunnels are 591 dynamically encapsulating, used on demand, and don't need setup or 592 teardown. The two tunneling mechanisms are a hard state versus soft 593 state tradeoff. 595 This specification recommends for early phases of deployment, to use 596 GTP as the data-plane so a transition for it to use the LISP control- 597 plane can be achieved more easily. At later phases, the LISP data- 598 plane may be considered so a more dynamic way of using tunnels can be 599 achieved to support URLLC. 601 This specification recommends the use of procedures from 602 [I-D.ietf-lisp-eid-mobility] and NOT the use of LISP-MN 603 [I-D.ietf-lisp-mn]. Using LISP-MN states that a LISP xTR reside on 604 the mobile UE. This is to be avoided so extra encapsulation header 605 overhead is NOT sent on the RAN. The LISP data-plane or control- 606 plane will not run on the UE. 608 8. Roaming and Packet Loss 610 Using LISP for the data-plane has some advantages in terms of 611 providing near-zero packet loss. In the current mobile network, 612 packets are queued on the gNB/eNodeB node the UE is roaming to or 613 rerouted on the gNB/eNodeB node the UE has left. In the LISP 614 architecture, packets can be sent to multiple "roamed-from" and 615 "roamed-to" nodes while the UE is moving or is off the RAN. See 616 mechanisms in [I-D.ietf-lisp-predictive-rlocs] for details. 618 9. Mobile Network LISP Mapping System 620 The LISP mapping system stores and maintains EID-to-RLOC mappings. 621 There are two mapping database transport systems that are available 622 for scale, LISP-ALT [RFC6836] and LISP-DDT [RFC8111]. The mapping 623 system will store EIDs assigned to UE nodes and the associated RLOCs 624 assigned to gNB/eNodeB nodes and UPF/pGW nodes. The RLOC addresses 625 are routable addresses by the NGC/EPC network. 627 This specification recommends the use of LISP-DDT. 629 10. LISP Over the 5G N3/N6/N9 Interfaces 631 So far in this specification we have described how LISP runs on the 632 gNB and UPF nodes in the mobile network. In the 5G architecture 633 [ARCH5G-3GPP] definition, some key components are Access and Mobility 634 Management Function (AMF) and the Session Management Function (SMF). 635 These two components provide control plane functionality to off-load 636 session anchoring by distributing state and packet flow among 637 multiple nodes in the NGC. These functions can be deployed in Branch 638 Point Uplink Classifier (BP/ULCL) in data-plane nodes. 640 Here is an illustration where a B/ULCL-UPF node would appear in the 641 mobile network: 643 (--------------------------------------------) 644 ( Internet ) 645 +-> (--------------------------------------------) 646 | | 647 N6 | 648 | (---------|---------) 649 +-> ( UPF ) <-+ 650 NGC ( [p1,p2] ) | 651 ( ) N9 652 +-> ( BP/ULCL ) | 653 | ( UPF [p3,p4] ) <-+ 654 N3 ( ) 655 | ( [a1] [a2] ) 656 +-> ( gNB gNB ) 657 (---/--\-----/--\---) 658 / \ / \ 659 / \ 660 / RAN \ 661 / \ 662 ( UE UE UE ) 663 a::1 a::2 a::3 665 The BP/ULCL-UPF node is configured as an LISP RTR and uses the 666 Traffic Engineering features of LISP specified in [I-D.ietf-lisp-te]. 667 In LISP-TE an Explicit Locator Path (ELP) can be stored in the RLOC- 668 record for any given EID thereby allowing packet flow from a UE to 669 the Internet to traverse through the BP/UCLC-UPF node. A UE 670 originated packet is encapsulated by the gNB to the BP/ULCL-UPF which 671 decapsulates and reencapsulates to the UPF at the Internet border. 672 This allows LISP to run over the 5G N3 and N9 interface with one 673 mapping entry. And if the ELP contained an xTR outside of the mobile 674 network, LISP could also run over the N6 interface. 676 The contents of the LISP mapping database: 678 EID-Record RLOC-Record Commentary 679 0::/0 [ELP{a1,p3,p1}, 4 RLOC-records, 2 with paths through the BP-UPF 680 ELP{a1,p4,p2}, and 2 directly to the border UPF from UEs 681 p1, p2] connected to gNB with RLOC a1 683 a::1/128 [a1,a2] The UPF or BP-UPF can encap directly for UE with 684 EID a::1 to either gNB with optimized latency 686 a::2/128 [ELP{p1,p3,a2}, The UPF can encap to either RLOC p3 or p4 to 687 ELP{p1,p4,a2}] forward traffic through the BP-UPF on its way 688 toward gNB with RLOC a1 690 a::3/128 [ELP{p1,p3,a2}, The UPF can encap to the BP-UPF or directly 691 a2] to gNB with RLOC a2 to reach UE with EID a::3 693 11. Multicast Considerations 695 Since the mobile network runs the LISP control-plane, and the mapping 696 system is available to support EIDs for unicast packet flow, it can 697 also support multicast packet flow. Support for multicast can be 698 provided by the LISP/GTP overlay with no changes to the NGC/EPC 699 network. 701 Multicast (S-EID,G) entries can be stored and maintained in the same 702 mapping database that is used to store UE based EIDs. Both Internet 703 connected nodes, as well as UE nodes, can source multicast packets. 704 The protocol procedures from [I-D.ietf-lisp-signal-free-multicast] 705 are followed to make multicast delivery available. Both multicast 706 packet flow and UE mobility can occur at the same time. 708 A day in the life of a 1-to-many multicast packet: 710 1. A UE node joins an (S,G) multicast flow by using IGMPv2 or 711 IGMPv3. 713 2. The gNB/eNodeB node records which UE on the RAN should get 714 packets sourced by S and destined for group G. 716 3. The gNB/eNodeB node registers the (S,G) entry to the mapping 717 system with its RLOC according to the receiver site procedures in 718 [I-D.ietf-lisp-signal-free-multicast]. The gNB/eNodeB does this 719 to show interest in joining the multicast flow. 721 4. When other UE nodes join the same (S,G), their associated gNB/ 722 eNodeB nodes will follow the procedures in steps 1 through 3. 724 5. The (S,G) entry stored in the mapping database has an RLOC-set 725 which contains a replication list of all the gNB/eNodeB RLOCs 726 that registered. 728 6. A multicast packet from source S to destination group G arrives 729 at the UPF/pGW. The UPF/pGW node looks up (S,G), gets returned 730 the replication list of all joined gNB/eNodeB nodes and 731 replicates the multicast packet by encapsulating the packet to 732 each of them. 734 7. Each gNB/eNodeB node decapsulates the packet and delivers the 735 multicast packet to one or more IGMP-joined UEs on the RAN. 737 12. Security Considerations 739 For control-plane authentication and authorization procedures, this 740 specification recommends the mechanisms in 741 [I-D.ietf-lisp-rfc6833bis], LISP-SEC [I-D.ietf-lisp-sec] AND LISP- 742 ECDSA [I-D.farinacci-lisp-ecdsa-auth]. 744 For data-plane privacy procedures, this specification recommends the 745 mechanisms in [RFC8061] When the LISP data-plane is used. otherwise, 746 the NGC/EPC must provide data-plane encryption support. 748 13. IANA Considerations 750 There are no specific requests for IANA. 752 14. SDO Recommendations 754 The authors request other Standards Development Organizations to 755 consider LISP as a technology for device mobility. It is recommended 756 to start with this specification as a basis for design and develop 757 more deployment details in the appropriate Standards Organizations. 758 The authors are willing to facilitate this activity. 760 15. References 762 15.1. Normative References 764 [RFC1700] Reynolds, J. and J. Postel, "Assigned Numbers", RFC 1700, 765 DOI 10.17487/RFC1700, October 1994, 766 . 768 [RFC6830] Farinacci, D., Fuller, V., Meyer, D., and D. Lewis, "The 769 Locator/ID Separation Protocol (LISP)", RFC 6830, 770 DOI 10.17487/RFC6830, January 2013, 771 . 773 [RFC6832] Lewis, D., Meyer, D., Farinacci, D., and V. Fuller, 774 "Interworking between Locator/ID Separation Protocol 775 (LISP) and Non-LISP Sites", RFC 6832, 776 DOI 10.17487/RFC6832, January 2013, 777 . 779 [RFC6833] Fuller, V. and D. Farinacci, "Locator/ID Separation 780 Protocol (LISP) Map-Server Interface", RFC 6833, 781 DOI 10.17487/RFC6833, January 2013, 782 . 784 [RFC6836] Fuller, V., Farinacci, D., Meyer, D., and D. Lewis, 785 "Locator/ID Separation Protocol Alternative Logical 786 Topology (LISP+ALT)", RFC 6836, DOI 10.17487/RFC6836, 787 January 2013, . 789 [RFC8060] Farinacci, D., Meyer, D., and J. Snijders, "LISP Canonical 790 Address Format (LCAF)", RFC 8060, DOI 10.17487/RFC8060, 791 February 2017, . 793 [RFC8061] Farinacci, D. and B. Weis, "Locator/ID Separation Protocol 794 (LISP) Data-Plane Confidentiality", RFC 8061, 795 DOI 10.17487/RFC8061, February 2017, 796 . 798 [RFC8111] Fuller, V., Lewis, D., Ermagan, V., Jain, A., and A. 799 Smirnov, "Locator/ID Separation Protocol Delegated 800 Database Tree (LISP-DDT)", RFC 8111, DOI 10.17487/RFC8111, 801 May 2017, . 803 15.2. Informative References 805 [ARCH5G-3GPP] 806 "System Architecture for the 5G System", TS.23.501 807 https://portal.3gpp.org/desktopmodules/Specifications/ 808 SpecificationDetails.aspx?specificationId=3144, December 809 2016. 811 [EPS-3GPP] 812 "Non-Access-Stratum (NAS) Protocol for Evolved Packet 813 System (EPS); Stage 3", TS.23.501 814 https://portal.3gpp.org/desktopmodules/specifications/ 815 specificationdetails.aspx?specificationid=1072, December 816 2017. 818 [ETSI-NGP] 819 "NGP Evolved Architecture for mobility using Identity 820 Oriented Networks", NGP-004, version 0.0.3 821 https://portal.etsi.org/webapp/WorkProgram/ 822 Report_WorkItem.asp?WKI_ID=50531, May 2017. 824 [FMC] "FIXED MOBILE CONVERGENCE", 825 https://www.ipv6.com/mobile/fixed-mobile-convergence/, 826 November 2006. 828 [GPRS-3GPP] 829 "General Packet Radio Service (GPRS) for Evolved Universal 830 Terrestrial Radio Access Network (E-UTRAN) Access", 831 TS23.401 Release 8 832 https://portal.3gpp.org/desktopmodules/specifications/ 833 specificationdetails.aspx?specificationid=849, January 834 2015. 836 [GTPv1-3GPP] 837 "General Packet Radio System (GPRS) Tunnelling Protocol 838 User Plane (GTPv1-U)", TS.29.281 839 https://portal.3gpp.org/desktopmodules/Specifications/ 840 SpecificationDetails.aspx?specificationId=1699, January 841 2015. 843 [GTPv2-3GPP] 844 "3GPP Evolved Packet System (EPS); Evolved General Packet 845 Radio Service (GPRS) Tunnelling Protocol for Control plane 846 (GTPv2-C); Stage 3", TS.29.274 847 https://portal.3gpp.org/desktopmodules/Specifications/ 848 SpecificationDetails.aspx?specificationId=1692, January 849 2015. 851 [I-D.farinacci-lisp-ecdsa-auth] 852 Farinacci, D. and E. Nordmark, "LISP Control-Plane ECDSA 853 Authentication and Authorization", draft-farinacci-lisp- 854 ecdsa-auth-03 (work in progress), September 2018. 856 [I-D.ietf-lisp-eid-anonymity] 857 Farinacci, D., Pillay-Esnault, P., and W. Haddad, "LISP 858 EID Anonymity", draft-ietf-lisp-eid-anonymity-07 (work in 859 progress), October 2019. 861 [I-D.ietf-lisp-eid-mobility] 862 Portoles-Comeras, M., Ashtaputre, V., Moreno, V., Maino, 863 F., and D. Farinacci, "LISP L2/L3 EID Mobility Using a 864 Unified Control Plane", draft-ietf-lisp-eid-mobility-05 865 (work in progress), November 2019. 867 [I-D.ietf-lisp-introduction] 868 Cabellos-Aparicio, A. and D. Saucez, "An Architectural 869 Introduction to the Locator/ID Separation Protocol 870 (LISP)", draft-ietf-lisp-introduction-13 (work in 871 progress), April 2015. 873 [I-D.ietf-lisp-mn] 874 Farinacci, D., Lewis, D., Meyer, D., and C. White, "LISP 875 Mobile Node", draft-ietf-lisp-mn-07 (work in progress), 876 March 2020. 878 [I-D.ietf-lisp-predictive-rlocs] 879 Farinacci, D. and P. Pillay-Esnault, "LISP Predictive 880 RLOCs", draft-ietf-lisp-predictive-rlocs-05 (work in 881 progress), November 2019. 883 [I-D.ietf-lisp-rfc6830bis] 884 Farinacci, D., Fuller, V., Meyer, D., Lewis, D., and A. 885 Cabellos-Aparicio, "The Locator/ID Separation Protocol 886 (LISP)", draft-ietf-lisp-rfc6830bis-32 (work in progress), 887 March 2020. 889 [I-D.ietf-lisp-rfc6833bis] 890 Farinacci, D., Maino, F., Fuller, V., and A. Cabellos- 891 Aparicio, "Locator/ID Separation Protocol (LISP) Control- 892 Plane", draft-ietf-lisp-rfc6833bis-27 (work in progress), 893 January 2020. 895 [I-D.ietf-lisp-sec] 896 Maino, F., Ermagan, V., Cabellos-Aparicio, A., and D. 897 Saucez, "LISP-Security (LISP-SEC)", draft-ietf-lisp-sec-20 898 (work in progress), January 2020. 900 [I-D.ietf-lisp-signal-free-multicast] 901 Moreno, V. and D. Farinacci, "Signal-Free LISP Multicast", 902 draft-ietf-lisp-signal-free-multicast-09 (work in 903 progress), March 2018. 905 [I-D.ietf-lisp-te] 906 Farinacci, D., Kowal, M., and P. Lahiri, "LISP Traffic 907 Engineering Use-Cases", draft-ietf-lisp-te-05 (work in 908 progress), October 2019. 910 [ITU-IMT2020] 911 "Focus Group on IMT-2020", 912 https://www.itu.int/dms_pubrec/itu-r/rec/m/R-REC- 913 M.687-2-199702-I!!PDF-E.pdf. 915 [LTE401-3GPP] 916 "General Packet Radio Service (GPRS) enhancements for 917 Evolved Universal Terrestrial Radio Access Network 918 (E-UTRAN) access", TS.23.401 919 https://portal.3gpp.org/desktopmodules/Specifications/ 920 SpecificationDetails.aspx?specificationId=849, January 921 2015. 923 [LTE402-3GPP] 924 "Architecture enhancements for non-3GPP accesses", 925 TS.23.402 926 https://portal.3gpp.org/desktopmodules/Specifications/ 927 SpecificationDetails.aspx?specificationId=850, January 928 2015. 930 [mMTC] "NGMN KPIs and Deployment Scenarios for Consideration for 931 IMT2020", https://www.ngmn.org/uploads/media/151204_NGMN_ 932 KPIs_and_Deployment_Scenarios_for_Consideration_for_IMT_20 933 20_-_LS_Annex_V1_approved.pdf, December 2015. 935 [NGMN] "5G End-to-End Architecture Framework", NGMN 936 https://www.ngmn.org/uploads/ 937 media/170511_NGMN_E2EArchFramework_v0.6.5.pdf, March 2016. 939 [PROC5G-3GPP] 940 "Procedures for the 5G System", TS.23.502 941 https://portal.3gpp.org/desktopmodules/Specifications/ 942 SpecificationDetails.aspx?specificationId=3145, December 943 2016. 945 [X2-3GPP] "Evolved Universal Terrestrial Radio Access Network 946 (E-UTRAN); X2 Application Protocol (X2AP)", TS.36.423 947 https://portal.3gpp.org/desktopmodules/Specifications/ 948 SpecificationDetails.aspx?specificationId=2452, June 2017. 950 Appendix A. Acknowledgments 952 The authors would like to thank Gerry Foster and Peter Ashwood Smith 953 for their expertise with 3GPP mobile networks and for their early 954 review and contributions. The authors would also like to thank Fabio 955 Maino, Malcolm Smith, and Marc Portoles for their expertise in both 956 5G and LISP as well as for their early review comments. 958 The authors would like to give a special thank you to Ryosuke 959 Kurebayashi from NTT Docomo and Kalyani Bogineni from Verizon for 960 their operational and practical commentary. 962 Appendix B. Document Change Log 964 B.1. Changes to draft-farinacci-lisp-mobile-network-08 966 o Posted March 2020. 968 o Change author affliations. 970 B.2. Changes to draft-farinacci-lisp-mobile-network-07 972 o Posted March 2020. 974 o Update references and document timer. 976 B.3. Changes to draft-farinacci-lisp-mobile-network-06 978 o Posted September 2019. 980 o Update references and document timer. 982 B.4. Changes to draft-farinacci-lisp-mobile-network-05 984 o Posted March 2019. 986 o Update references and document timer. 988 B.5. Changes to draft-farinacci-lisp-mobile-network-04 990 o Posted September 2018. 992 o Update document timer. 994 B.6. Changes to draft-farinacci-lisp-mobile-network-03 996 o Posted March 2018. 998 o Make the spec more 5G user-friendly. That is, the design has 999 always worked for either 4G or 5G but we make it more clear about 1000 5G by using some basic 5G node terminlogy. 1002 o Add a section how LISP can work on the N3, N6, and N9 5G spec 1003 interfaces. 1005 o Describe how LISP-TE can allow BP-UPF offload functionality. 1007 B.7. Changes to draft-farinacci-lisp-mobile-network-02 1009 o Posted mid September 2017. 1011 o Editorial fixes from draft -01. 1013 B.8. Changes to draft-farinacci-lisp-mobile-network-01 1015 o Posted September 2017. 1017 o Explain each EID case illustrated in the "Mobile Network with EID/ 1018 RLOC Assignment" diagram. 1020 o Make a reference to mMTC as a 3GPP use-case for 5G. 1022 o Add to the requirements section how mobile operators believe that 1023 using Locator/ID separation mechanisms provide for more efficient 1024 mobile netwowks. 1026 o Indicate that L2-overlays is not recommended by this specification 1027 as the LISP mobile network architeture but how operators may want 1028 to deploy a layer-2 overlay service. 1030 B.9. Changes to draft-farinacci-lisp-mobile-network-00 1032 o Initial draft posted August 2017. 1034 Authors' Addresses 1036 Dino Farinacci 1037 lispers.net 1038 San Jose, CA 1039 USA 1041 Email: farinacci@gmail.com 1043 Padma Pillay-Esnault 1044 Independent 1045 Santa Clara, CA 1046 USA 1048 Email: padma.ietf@gmail.com 1049 Uma Chunduri 1050 Futurewei Technologies 1051 Santa Clara, CA 1052 USA 1054 Email: umac.ietf@gmail.com