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Checking references for intended status: Experimental ---------------------------------------------------------------------------- == Unused Reference: 'I-D.ietf-lisp-eid-anonymity' is defined on line 575, but no explicit reference was found in the text ** Obsolete normative reference: RFC 6830 (Obsoleted by RFC 9300, RFC 9301) == Outdated reference: A later version (-15) exists of draft-farinacci-lisp-geo-06 == Outdated reference: A later version (-16) exists of draft-ietf-lisp-eid-anonymity-04 == Outdated reference: A later version (-13) exists of draft-ietf-lisp-eid-mobility-03 == Outdated reference: A later version (-29) exists of draft-ietf-lisp-sec-16 Summary: 1 error (**), 0 flaws (~~), 6 warnings (==), 1 comment (--). 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: May 23, 2019 Huawei Technologies 6 November 19, 2018 8 LISP Predictive RLOCs 9 draft-ietf-lisp-predictive-rlocs-03 11 Abstract 13 This specification describes a method to achieve near-zero packet 14 loss when an EID is roaming quickly across RLOCs. 16 Requirements Language 18 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 19 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 20 document are to be interpreted as described in [RFC2119]. 22 Status of This Memo 24 This Internet-Draft is submitted in full conformance with the 25 provisions of BCP 78 and BCP 79. 27 Internet-Drafts are working documents of the Internet Engineering 28 Task Force (IETF). Note that other groups may also distribute 29 working documents as Internet-Drafts. The list of current Internet- 30 Drafts is at https://datatracker.ietf.org/drafts/current/. 32 Internet-Drafts are draft documents valid for a maximum of six months 33 and may be updated, replaced, or obsoleted by other documents at any 34 time. It is inappropriate to use Internet-Drafts as reference 35 material or to cite them other than as "work in progress." 37 This Internet-Draft will expire on May 23, 2019. 39 Copyright Notice 41 Copyright (c) 2018 IETF Trust and the persons identified as the 42 document authors. All rights reserved. 44 This document is subject to BCP 78 and the IETF Trust's Legal 45 Provisions Relating to IETF Documents 46 (https://trustee.ietf.org/license-info) in effect on the date of 47 publication of this document. Please review these documents 48 carefully, as they describe your rights and restrictions with respect 49 to this document. Code Components extracted from this document must 50 include Simplified BSD License text as described in Section 4.e of 51 the Trust Legal Provisions and are provided without warranty as 52 described in the Simplified BSD License. 54 Table of Contents 56 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 57 2. Definition of Terms . . . . . . . . . . . . . . . . . . . . . 3 58 3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 3 59 4. Design Details . . . . . . . . . . . . . . . . . . . . . . . 5 60 4.1. RLE Encoding . . . . . . . . . . . . . . . . . . . . . . 6 61 4.2. Packet Delivery Optimizations . . . . . . . . . . . . . . 7 62 4.3. Trading Off Replication Cost . . . . . . . . . . . . . . 8 63 5. Directional Paths with Intersections . . . . . . . . . . . . 9 64 6. Multicast Considerations . . . . . . . . . . . . . . . . . . 10 65 7. Multiple Address-Family Considerations . . . . . . . . . . . 11 66 8. Scaling Considerations . . . . . . . . . . . . . . . . . . . 11 67 9. Security Considerations . . . . . . . . . . . . . . . . . . . 12 68 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 69 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 70 11.1. Normative References . . . . . . . . . . . . . . . . . . 12 71 11.2. Informative References . . . . . . . . . . . . . . . . . 13 72 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 14 73 Appendix B. Document Change Log . . . . . . . . . . . . . . . . 14 74 B.1. Changes to draft-ietf-lisp-predictive-rlocs-03 . . . . . 14 75 B.2. Changes to draft-ietf-lisp-predictive-rlocs-02 . . . . . 14 76 B.3. Changes to draft-ietf-lisp-predictive-rlocs-01 . . . . . 14 77 B.4. Changes to draft-ietf-lisp-predictive-rlocs-00 . . . . . 14 78 B.5. Changes to draft-farinacci-lisp-predictive-rlocs-02 . . . 14 79 B.6. Changes to draft-farinacci-lisp-predictive-rlocs-01 . . . 15 80 B.7. Changes to draft-farinacci-lisp-predictive-rlocs-00 . . . 15 81 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 83 1. Introduction 85 The LISP architecture [RFC6830] specifies two namespaces, End-Point 86 IDs (EIDs) and Routing Locators (RLOCs). An EID identifies a node in 87 the network and the RLOC indicates the EID's topological location. 88 When an node roams in the network, its EID remains fixed and 89 unchanged but the RLOCs associated with it change to reflect its new 90 topological attachment point. This specification will focus EIDs and 91 RLOCs residing in separate nodes. An EID is assigned to a host node 92 that roams while the RLOCs are assigned to network nodes that stay 93 stationary and are part of the network topology. For example, a set 94 of devices on an aircraft are assigned EIDs, and base stations on the 95 ground attached to the Internet infrastructure are configured as LISP 96 xTRs where their RLOCs are used for the bindings of the EIDs on the 97 aircraft up in the air. 99 The scope of this specification will not emphasize general physical 100 roaming as an aircraft would do in the sky but in a direction that is 101 more predictable such as a train traveling on a track or vehicle that 102 travels along a road. 104 2. Definition of Terms 106 Roaming-EID - is a network node that moves from one topological 107 location in the network to another. The network node uses the 108 same EID when it is roaming. That is, the EID address does not 109 change for reasons of mobility. A roaming-EID can also be a 110 roaming EID-prefix where a set of EIDs covered by the prefix are 111 all roaming and fate-sharing the same set of RLOCs at the same 112 time. 114 Predictive RLOCs - is a set of ordered RLOCs in a list each assigned 115 to LISP xTRs where the next RLOC in the list has high probability 116 it will be the next LISP xTR in a physical path going in a single 117 predictable direction. 119 Road-Side-Units (RSUs) - is a network node that acts as a router, 120 more specifically as a LISP xTR. The xTR automatically discovers 121 roaming-EIDs that come into network connectivity range and relays 122 packets to and from the roaming-EID. RSUs are typically deployed 123 along a directional path like a train track or road and are in 124 connectivity range of devices that travel along the directional 125 path. 127 3. Overview 129 The goal of this specification is to describe a make-before-break 130 EID-mobility mechanism that offers near-zero packet loss. Offering 131 minimal packet loss, not only allows transport layers to operate more 132 efficiently, but because an EID does not change while moving, 133 transport layer session continuity is maintained. To achieve these 134 requirements, a mechanism that reacts to the mobility event is 135 necessary but not sufficient. So the question is not that there 136 isn't a reaction but when it happens. By using some predictive 137 algorithms, we can guess with high probability where the EID will 138 roam to next. We can achieve this to a point where packet data will 139 be at the new location when the EID arrives. 141 First we should examine both the send and receive directions with 142 respect to the roaming-EID. Refer to Figure 1 for discussion. We 143 show a network node with a fixed EID address assigned to a roaming- 144 EID moving along a train track. And there are LISP xTRs deployed as 145 Road-Side-Units to support the connectivity between the roaming-EID 146 and the infrastructure or to another roaming-EID. 148 Roaming-EID ----> 150 ====//====//====//====//====//====//====//====//===//====//====//==== 151 // // // // // // // // // // // 152 ====//====//====//====//====//====//====//====//===//====//====//==== 154 xTR xTR xTR xTR xTR xTR 155 A B C D E F 157 Figure 1: Directional Mobility 159 For the send direction from roaming-EID to any destination can be 160 accomplish as a local decision. As long as the roaming-EID is in 161 signal range to any xTR along the path, it can use it to forward 162 packets. The LISP xTR, acting as an ITR, can forward packets to 163 destinations in non-LISP sites as well as to stationary and roaming 164 EIDs in LISP sites. This is accomplished by using the LISP overlay 165 via dynamic packet encapsulation. When the roaming-EID sends 166 packets, the LISP xTR must discover the EID and MAY register the EID 167 with a set of RLOCs to the mapping system 168 [I-D.ietf-lisp-eid-mobility]. The discovery process is important 169 because the LISP xTR, acting as an ETR for decapsulating packets that 170 arrive, needs to know what local ports or radios to send packets to 171 the roaming-EID. 173 Much of the focus of this design is on the packet direction to the 174 roaming-EID. And how remote LISP ITRs find the current location 175 (RLOCs) quickly when the roaming-EID is moving at high speed. This 176 specification solves the fast roaming with the introduction of the 177 Predictive-RLOCs algorithm. 179 Since a safe assumption is that the roaming-EID is going in one 180 direction and cannot deviate from it allows us to know a priori the 181 next set of RLOCs the roaming-EID will pass by. Referring to 182 Figure 1, if the roaming-EID is in range near xTR-A, then as it 183 moves, it will at some point pass by xTR-B and xTR-C, and so on. As 184 the roaming-EID moves, one could time when the EID is mapped to RLOC 185 A, and when it should change to RLOC B and so on. However, the speed 186 of movement of the roaming-EID won't be constant and the variables 187 involved in consistent timing cannot be relied on. Furthermore, 188 timing the move is not a make-before-break algorithm, meaning the 189 reaction of the binding happens at the time the roaming-EID is 190 discovered by an xTR. One cannot achieve fast hand-offs when message 191 signaling will be required to inform remote ITRs of the new binding. 193 The Predictive RLOCs algorithm allows a set of RLOCs, in an ordered 194 list, to be provided to remote ITRs so they have the information 195 available and local for when they need to use it. Therefore, no 196 control-plane message signaling occurs when the roaming-EID is 197 discovered by LISP xTRs. 199 4. Design Details 201 Predictive RLOCs accommodates for encapsulated packets to be 202 delivered to Road-Side-Unit LISP xTRs regardless where the roaming- 203 EID is currently positioned. 205 Referring to Figure 1, the following sequence is performed: 207 1. The Predictive RLOCs are registered to the mapping system as a 208 LCAF encoded Replication List Entry (RLE) Type [RFC8060]. The 209 registration can happen by one or more RSUs or by a third-party. 210 When registered by an RSU, and when no coordination is desired, 211 they each register their own RLOC with merge-semantics so the 212 list can be created and maintained in the LISP Map-Server. When 213 registered by a third-party, the complete list of RLOCs can be 214 included in the RLE. 216 2. There can be multiple RLEs present each as different RLOC- 217 records so a remote ITR can select one RLOC-record versus the 218 other based in priority and weight policy [RFC6830]. 220 3. When a remote ITR receives a packet destined for a roaming-EID, 221 it encapsulates and replicates to each RLOC in the RLE thereby 222 delivering the packet to the locations the roaming-EID is about 223 to appear. There are some cases where packets will go to 224 locations where the roaming-EID has already been, but see 225 Section 4.2 for packet delivery optimizations. 227 4. When the ETR resident RSU receives an encapsulated packet, it 228 decapsulates the packet and then determines if the roaming-EID 229 had been previously discovered. If the EID has not been 230 discovered, the ETR drops the packet. Otherwise, the ETR 231 delivers the decapsulated packet on the port interface the 232 roaming-EID was discovered on. 234 4.1. RLE Encoding 236 The LCAF [RFC8060] Replication List Entry (RLE) will be used to 237 encode the Predictive RLOCs in an RLOC-record for Map-Registers, Map- 238 Reply, and Map-Notify messages [RFC6830]. 240 0 1 2 3 241 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 242 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 243 | AFI = 16387 | Rsvd1 | Flags | 244 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 245 | Type = 13 | Rsvd2 | 4 + n | 246 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 247 | Rsvd3 | Rsvd4 | Level Value | 248 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 249 | AFI = x | RTR/ETR #1 ... | 250 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 251 | Rsvd3 | Rsvd4 | Level Value | 252 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 253 | AFI = x | RTR/ETR #n ... | 254 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 256 When the RLOC-record contains an RLE with RLOC entries all with the 257 same level value, it means the physical order listed is the 258 directional path of the RSUs. This will typically be the result of a 259 third-party doing the registration where it knows ahead of time the 260 RSU deployment. 262 When each RSU is registering with merge-semantics on their own, the 263 level number is used to place them in an ordered list. Since the 264 registrations come at different times and therefore arrive in 265 different order than the physical RSU path, the level number creates 266 the necessary sequencing. Each RSU needs to know its position in the 267 path relative to other RSUs. For example, in xTR-B, it would 268 register with level 1 since it is after xTR-A (and before xTR-C). So 269 if the registration order was xTR-B with level 1, xTR-C with level 2, 270 and xTR-A with level 0, the RLE list stored in the mapping system 271 would be (xTR-A, xTR-B, xTR-C). It is recommended that level numbers 272 be assigned in increments of 10 so latter insertion is possible. 274 The use of Geo-Prefixes and Geo-Points [I-D.farinacci-lisp-geo] can 275 be used to compare the physical presence of each RSU with respect to 276 each other, so they can choose level numbers to sequence themselves. 277 Also if the xTRs register with a Geo-Point in an RLOC-record, then 278 perhaps the Map-Server could sequence the RLE list. 280 4.2. Packet Delivery Optimizations 282 Since the remote ITR will replicate to all RLOCs in the RLE, a 283 situation is created where packets go to RLOCs that don't need to. 284 For instance, if the roaming-EID is along side of xTR-B and the RLE 285 is (xTR-A, xTR-B, xTR-C), there is no reason to replicate to xTR-A 286 since the roaming-EID has passed it and the the signal range is weak 287 or lost. However, replicating to xTR-B and xTR-C is important to 288 deliver packets to where the roaming-EID resides and where it is 289 about to go to. 291 A simple data-plane option, which converges fairly quickly is to have 292 the remote xTR, acting as an ETR, when packets are sent from the 293 roaming-EID, examine the source RLOC in the outer header of the 294 encapsulated packet. If the source RLOC is xTR-B, the remote xTR can 295 determine that the roaming-EID has moved past xTR-A and no longer 296 needs to encapsulate packets to xTR-A's RLOC. 298 In addition, the remote ITR can use RLOC-probing to determine if each 299 RLOC in the RLE is reachable. And if not reachable, exclude from the 300 list of RLOCs to replicate to. 302 This solution also handles the case where xTR-A and xTR-B may overlap 303 in radio signal range, but the signal is weak from the roaming-EID to 304 xTR-A but stronger to xTR-B. In this case, the roaming-EID selects 305 xTR-B to send packets that inform the remote xTR that return packets 306 should not be encapsulated to xTR-A. 308 There are also situations where the RSUs are in signal range of each 309 other in which case they could report reachability status of each 310 other. The use of the Locator-Status-Bits of the LISP encapsulation 311 header could be used to convey this information to the remote xTR. 312 This would only occur when the roaming-EID was discovered by both 313 xTR-A and xTR-B so it was possible for either xTR to reach the 314 roaming-EID. Either an IGP like routing protocol would be required 315 to allow each xTR to know the other could reach the roaming-EID or a 316 path trace tool (i.e. traceroute) could be originated by one xTR 317 targeted for the roaming-EID but MAC-forwarded through the other xTR. 318 These and other roaming-EID reachability mechanisms are work in 319 progress and for further study. 321 When a remote ITR is doing "Directional Mobility" and replicating to 322 the last RLOC in the RLE list, it has a decision to guess where the 323 roaming-EID will move to next. Conservatively, an ITR can replicate 324 to the entire set of RLOCs in the RLE list and wait to see if the 325 roaming-EID moves to one of the RLOCs in the RLE list. 327 Or more liberally, the remote ITR can assume the new roaming 328 direction. For example, with an RLE list of (xTR-A, xTR-B, xTR-C, 329 xTR-D) and the roaming-EID is at D, the remote ITR can replicate to 330 all of A, B, C and D to determine where the roaming-EID will move to 331 next. If the roaming-EID moves to C after it was at D, it is 332 possible that the EID is moving in the opposite direction from C to B 333 to A. This would be known as "Back-n-Forth Mobility". If an 334 implementation is configured to support this for a particluar EID, 335 the remote ITR could replicate in this sequence as the roaming-EID 336 moves from A to D and back to A: (A, B, C, D), (B, C, D), (C, D), (D, 337 C, B, A), (C, B, A), (B, A), and again (A, B, C, D). 339 The roaming-EID could be doing "Circular Mobility" where it moves 340 from A to D directionally, next from D-to-A, and then back to A to D 341 directionally again. This form of mobility is just as predicatable 342 as "Back-n-Forth Mobility" since a consistent pattern can be relied 343 on. Both of these mobility forms can be achieved with near-zero 344 packet loss. 346 On the other hand, the roaming-EID can be roaming arbitrarily using 347 "Random Mobility" where it could roam in the following combinations: 348 A-to-B, A-to-C, A-to-D, B-to-A, B-to-C, B-to-D, C-to-A, C-to-B, C-to- 349 D, D-to-A, D-to-B, or D-to-C. In this situation, when a return 350 packet arrives at the ITR, it could then just replicate to where the 351 roaming-EID is at rest and do so for a short period of time before it 352 replciates to the entire RLE list again. Using the wrong time period 353 could lead to packet loss. All these types of mobility can be 354 supported by the remote ITR in a local manner without consulting or 355 depending on any other LISP system. It is left for further study, if 356 any of the mobility types above should be encoded in the mapping 357 system. 359 4.3. Trading Off Replication Cost 361 If RLE lists are large, packet replication can occur to locations 362 well before the roaming-EID arrives. Making RLE lists small is 363 useful without sacrificing hand-off issues or incurring packet loss 364 to the application. By having overlapping RLEs in separate RLOC- 365 records we a simple mechanism to solve this problem. Here is an 366 example mapping entry to illustrate the point: 368 EID = , RLOC-records: 369 RLOC = (RLE: xTR-A, xTR-B) 370 RLOC = (RLE: xTR-B, xTR-C, xTR-D, xTR-E) 371 RLOC = (RLE: xTR-E, xTR-F) 373 When the remote ITR is encapsulating to xTR-B as a decision to use 374 the first RLOC-record, it can decide to move to use the second RLOC- 375 record because xTR-B is the last entry in the first RLOC-record and 376 the first entry in the second RLOC-record. When there are 377 overlapping RLEs, the remote ITR can decide when it is more efficient 378 to switch over. For example, when the roaming-EID is in range of 379 xTR-A, the remote ITR uses the first RLOC-record so the wasted 380 replication cost is to xTR-B only versus a worse cost when using the 381 second RLOC-record. But when the roaming-EID is in range of xTR-B, 382 then replicating to the other xTRs in the second RLOC-record may be 383 crucial if the roaming-EID has increased speed. And when the 384 roaming-EID may be at rest in a parked mode, then the remote ITR 385 encapsulates to only xTR-F using the third RLOC-record since the 386 roaming-EID has moved past xTR-E. 388 In addition, to eliminate unnecessary replication to xTRs further 389 down a directional path, GEO-prefixes [I-D.farinacci-lisp-geo] can be 390 used so only nearby xTRs that the roaming-EID is about to come in 391 contact with are the only ones to receive encapsulated packets. 393 Even when replication lists are not large, we can reduce the cost of 394 replication that the entire network bears by moving the replicator 395 away from the the source (i.e. the ITR) and closer to the RSUs (i.e. 396 the ETRs). See the use of RTRs for Replication Engineering 397 techniques in [RFC8378]. 399 5. Directional Paths with Intersections 401 A roaming-EID could be registered to the mapping system with the 402 following nested RLE mapping: 404 EID = , RLOC-records: 405 RLOC = (RLE: xTR-A, xTR-B, xTR-C, (RLE: xTR-X, xTR-Y, xTR-Z), 406 (RLE: xTR-I, xTR-J, xTR-K), xTR-D, xTR-E) 408 The mapping entry above describes 3 directional paths where the 409 ordered list has encoded one-level of two nested RLEs to denote 410 intersections in a horizontal path. Which is drawn as: 412 | | xTR-K 413 | | 414 | | 415 | | xTR-J 416 | | 417 | | 418 Roaming | | xTR-I 419 EID ----> | | 420 --------------------------------------- ------------------------------ 421 --------------------------------------- ------------------------------ 422 xTR-A xTR-B xTR-C | | xTR-D xTR-E 423 | | 424 | | xTR-X 425 | | 426 | | 427 | | xTR-Y 428 | | 429 | | 430 | | xTR-Z 432 When the roaming-EID is on the horizontal path, the remote-ITRs 433 typically replicate to the rest the of the xTRs in the ordered list. 434 When a list has nested RLEs, the replication should occur to at least 435 the first RLOC in a nested RLE list. So if the remote-ITR is 436 replicating to xTR-C, xTR-D, and xTR-E, it should also replicate to 437 xTR-X and xTR-I anticipating a possible turn at the intersection. 438 But when the roaming-EID is known to be at xTR-D (a left or right 439 hand turn was not taken), replication should only occur to xTR-D and 440 xTR-E. Once either xTR-I or xTR-X is determined to be where the 441 roaming-EID resides, then the replication occurs on the respective 442 directional path only. 444 When nested RLEs are used it may be difficult to get merge-semantics 445 to work when each xTR registers itself. So it is suggested a third- 446 party registers nested RLEs. It is left to further study to 447 understand better how to automate this. 449 6. Multicast Considerations 451 In this design, the remote ITR is receiving a unicast packet from an 452 EID and replicating and encapsulating to each RLOC in an RLE list. 453 This form of replication is no different than a traditional multicast 454 replication function. So replicating multicast packets in the same 455 fashion is a fallout from this design. 457 If there are multiple roaming-EIDs joined to the same multicast group 458 but reside at different RSUs, a merge has to be done of any pruned 459 RLEs used for forwarding. So if roaming-EID-1 resides at xTR-A and 460 roaming-EID-2 resides at xTR-B and the RLE list is (xTR-A, xTR-B, 461 xTR-C), and they are joined to the same multicast group, then 462 replication occurs to all of xTR-A, xTR-B, and xTR-C. Even since 463 roaming-EID-2 is past xTR-A, packets need to be delivered to xTR-A 464 for roaming-EID-1. In addition, packets need to be delivered to 465 xTR-C because roaming-EID-1 and roaming-EID-2 will get to xTR-C (and 466 roaming-EID-1 may get there sooner if it is traveling faster than 467 roaming-EID-2). 469 When a roaming-EID is a multicast source, procedures from [RFC8378] 470 are used to deliver packets to multicast group members anywhere in 471 the network. The solution requires no signaling to the RSUs. When 472 RSUs receive multicast packets from a roaming-EID, they do a 473 (roaming-EID,G) mapping database lookup to find the replication list 474 of ETRs to encapsulate to. 476 7. Multiple Address-Family Considerations 478 Note that roaming-EIDs can be assigned IPv6 EID addresses while the 479 RSU xTRs could be using IPv4 RLOC addresses. Any combination of 480 address-families can be supported as well as for multicast packet 481 forwarding, where (S,G) are IPv6 addresses entries and replication is 482 done with IPv4 RLOCs in the outer header. 484 8. Scaling Considerations 486 One can imagine there will be a large number of roaming-EIDs. So 487 there is a strong desire to efficiently store state in the mapping 488 database and the in remote ITRs map-caches. It is likely, that 489 roaming-EIDs may share the same path and move at the same speed (EID 490 devices on a train) and therefore share the same Predictive RLOCs. 491 And since EIDs are not reassigned for mobility purposes or may be 492 temporal , they will not be topologically aggregatable, so they 493 cannot compress into a single EID-prefix mapping entry that share the 494 same RLOC-set. 496 By using a level of indirection with the mapping system this problem 497 can be solved. The following mapping entries could exist in the 498 mapping database: 500 EID = , RLOC-records: 501 RLOC = (afi=: "am-train-to-paris") 502 EID = , RLOC-records: 503 RLOC = (afi=: "am-train-to-paris") 504 EID = , RLOC-records: 505 RLOC = (afi=: "am-train-to-paris") 507 EID = "am-train-to-paris", RLOC-records: 508 RLOC = (afi=lcaf/RLE-type: xTR-A, xTR-B, xTR-C) 510 EID = "am-train-to-paris-passengers", RLOC-records: 511 RLOC = (afi=lcaf/afi-list-type: , , ) 513 Each passenger that boards a train has their EID registered to point 514 to the name of the train "am-train-to-paris". And then the train 515 with EID "am-train-to-paris" stores the Predictive RLOC-set. When a 516 remote-ITR wants to encapsulate packets for an EID, it looks up the 517 EID in the mapping database gets the name "am-train-to-paris" 518 returned. Then the remote-ITR does another lookup for the name "am- 519 train-to-paris" to get the RLE list returned. 521 When new EIDs board the train, the RLE mapping entry does not need to 522 be modified. Only an EID-to-name mapping is registered for the 523 specific new EID. Optionally, another name "am-train-to-paris- 524 passengers" can be registered as an EID to allow mapping to all 525 specific EIDs which are on the train. This can be used for 526 inventory, billing, or security purposes. 528 This optimization comes at a cost of a 2-stage lookup. However, if 529 both sets of mapping entries are registered to the same Map-Server, a 530 combined RLOC-set could be returned. This idea is for further study. 532 9. Security Considerations 534 LISP has procedures for supporting both control-plane security 535 [I-D.ietf-lisp-sec] and data-plane security [RFC8061]. 537 10. IANA Considerations 539 At this time there are no requests for IANA. 541 11. References 543 11.1. Normative References 545 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 546 Requirement Levels", BCP 14, RFC 2119, 547 DOI 10.17487/RFC2119, March 1997, 548 . 550 [RFC6830] Farinacci, D., Fuller, V., Meyer, D., and D. Lewis, "The 551 Locator/ID Separation Protocol (LISP)", RFC 6830, 552 DOI 10.17487/RFC6830, January 2013, 553 . 555 [RFC8060] Farinacci, D., Meyer, D., and J. Snijders, "LISP Canonical 556 Address Format (LCAF)", RFC 8060, DOI 10.17487/RFC8060, 557 February 2017, . 559 [RFC8061] Farinacci, D. and B. Weis, "Locator/ID Separation Protocol 560 (LISP) Data-Plane Confidentiality", RFC 8061, 561 DOI 10.17487/RFC8061, February 2017, 562 . 564 [RFC8378] Moreno, V. and D. Farinacci, "Signal-Free Locator/ID 565 Separation Protocol (LISP) Multicast", RFC 8378, 566 DOI 10.17487/RFC8378, May 2018, 567 . 569 11.2. Informative References 571 [I-D.farinacci-lisp-geo] 572 Farinacci, D., "LISP Geo-Coordinate Use-Cases", draft- 573 farinacci-lisp-geo-06 (work in progress), October 2018. 575 [I-D.ietf-lisp-eid-anonymity] 576 Farinacci, D., Pillay-Esnault, P., and W. Haddad, "LISP 577 EID Anonymity", draft-ietf-lisp-eid-anonymity-04 (work in 578 progress), October 2018. 580 [I-D.ietf-lisp-eid-mobility] 581 Portoles-Comeras, M., Ashtaputre, V., Moreno, V., Maino, 582 F., and D. Farinacci, "LISP L2/L3 EID Mobility Using a 583 Unified Control Plane", draft-ietf-lisp-eid-mobility-03 584 (work in progress), November 2018. 586 [I-D.ietf-lisp-sec] 587 Maino, F., Ermagan, V., Cabellos-Aparicio, A., and D. 588 Saucez, "LISP-Security (LISP-SEC)", draft-ietf-lisp-sec-16 589 (work in progress), October 2018. 591 Appendix A. Acknowledgments 593 The author would like to thank the LISP WG for their review and 594 acceptance of this draft. 596 Appendix B. Document Change Log 598 [RFC Editor: Please delete this section on publication as RFC.] 600 B.1. Changes to draft-ietf-lisp-predictive-rlocs-03 602 o Posted November 2018. 604 o Update document timer and references. 606 B.2. Changes to draft-ietf-lisp-predictive-rlocs-02 608 o Posted May 2018. 610 o Update document timer and references. 612 B.3. Changes to draft-ietf-lisp-predictive-rlocs-01 614 o Posted November 2017. 616 o Update document timer and references. 618 o Reflect comments from Prague meeting presentation. There is no 619 need for "RLE Usage Types" as suggested. The ITR can treat what 620 RLOCs it replicates to as a local matter via implementation 621 configuration. RLE Directional is default. Circular rotation, 622 back-n-forth, and random selection of RLOCs is up to the ITR. 624 B.4. Changes to draft-ietf-lisp-predictive-rlocs-00 626 o Posted June 2017. 628 o Make this specification a working group document. It is a copy of 629 draft-farinacci-lisp-predictive-rlocs-02. 631 B.5. Changes to draft-farinacci-lisp-predictive-rlocs-02 633 o Posted May 2017 to update document timer. 635 B.6. Changes to draft-farinacci-lisp-predictive-rlocs-01 637 o Posted November 2016 to update document timer. 639 B.7. Changes to draft-farinacci-lisp-predictive-rlocs-00 641 o Initial post April 2016. 643 Authors' Addresses 645 Dino Farinacci 646 lispers.net 647 San Jose, CA 648 USA 650 Email: farinacci@gmail.com 652 Padma Pillay-Esnault 653 Huawei Technologies 654 San Clara, CA 655 USA 657 Email: padma@huawei.com