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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 6830 (Obsoleted by RFC 9300, RFC 9301) ** Obsolete normative reference: RFC 6833 (Obsoleted by RFC 9301) ** Obsolete normative reference: RFC 8113 (Obsoleted by RFC 9304) == Outdated reference: A later version (-07) exists of draft-boucadair-lisp-bulk-04 Summary: 3 errors (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group M. Boucadair 3 Internet-Draft C. Jacquenet 4 Intended status: Standards Track Orange 5 Expires: October 28, 2017 April 26, 2017 7 LISP Subscription 8 draft-boucadair-lisp-subscribe-05 10 Abstract 12 Mapping Services in Locator/ID Separation Protocol (LISP) networks 13 are key to proper LISP forwarding operation. When considering the 14 deployment of LISP at large scale, these Mapping Services are even 15 more crucial for the sake of the LISP forwarding efficiency. This 16 document introduces two additional LISP messages that are meant to 17 facilitate the dynamic discovery of Mapping Systems, improve Ingress 18 Tunnel Routers (ITR) recovery times and optimize the solicitation of 19 the LISP Mapping System as a function of the ITR location, in 20 particular. 22 Requirements Language 24 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 25 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 26 document are to be interpreted as described in RFC 2119 [RFC2119]. 28 Status of This Memo 30 This Internet-Draft is submitted in full conformance with the 31 provisions of BCP 78 and BCP 79. 33 Internet-Drafts are working documents of the Internet Engineering 34 Task Force (IETF). Note that other groups may also distribute 35 working documents as Internet-Drafts. The list of current Internet- 36 Drafts is at http://datatracker.ietf.org/drafts/current/. 38 Internet-Drafts are draft documents valid for a maximum of six months 39 and may be updated, replaced, or obsoleted by other documents at any 40 time. It is inappropriate to use Internet-Drafts as reference 41 material or to cite them other than as "work in progress." 43 This Internet-Draft will expire on October 28, 2017. 45 Copyright Notice 47 Copyright (c) 2017 IETF Trust and the persons identified as the 48 document authors. All rights reserved. 50 This document is subject to BCP 78 and the IETF Trust's Legal 51 Provisions Relating to IETF Documents 52 (http://trustee.ietf.org/license-info) in effect on the date of 53 publication of this document. Please review these documents 54 carefully, as they describe your rights and restrictions with respect 55 to this document. Code Components extracted from this document must 56 include Simplified BSD License text as described in Section 4.e of 57 the Trust Legal Provisions and are provided without warranty as 58 described in the Simplified BSD License. 60 Table of Contents 62 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 63 1.1. Issues . . . . . . . . . . . . . . . . . . . . . . . . . 3 64 1.2. Assumptions . . . . . . . . . . . . . . . . . . . . . . . 3 65 1.3. Improving LISP Mapping Services . . . . . . . . . . . . . 4 66 2. Map-Subscribe Message Format . . . . . . . . . . . . . . . . 5 67 3. Map-Subscribe-Ack Message Format . . . . . . . . . . . . . . 6 68 4. Generating a Map-Subscribe Message . . . . . . . . . . . . . 9 69 5. Processing a Map-Subscribe Message . . . . . . . . . . . . . 10 70 6. Processing a Map-Subscribe-Ack Message . . . . . . . . . . . 12 71 7. Subscription to Multiple Resolvers . . . . . . . . . . . . . 13 72 8. Sample Examples . . . . . . . . . . . . . . . . . . . . . . . 13 73 8.1. Map-Resolver Redirect . . . . . . . . . . . . . . . . . . 13 74 8.2. Mapping Cache Retrieval . . . . . . . . . . . . . . . . . 14 75 8.3. Unsolicited Map-Reply . . . . . . . . . . . . . . . . . . 16 76 9. Security Considerations . . . . . . . . . . . . . . . . . . . 17 77 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 78 11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17 79 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 17 80 12.1. Normative references . . . . . . . . . . . . . . . . . . 18 81 12.2. Informative references . . . . . . . . . . . . . . . . . 18 82 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18 84 1. Introduction 86 Locator/ID Separation Protocol (LISP, [RFC6830] ) operation relies 87 upon a mapping mechanism that is used by ingress/egress Tunnel 88 Routers (xTR) to forward traffic over the LISP network. The ability 89 of dynamically discovering the Map-Resolver and Map-Server entities 90 that provide such mapping services is meant to facilitate global LISP 91 operation. In particular, the ability to inform Ingress Tunnel 92 Routers (ITR) of a LISP network about the availability and the status 93 of several Mapping Services is likely to improve the overall LISP 94 forwarding serviceability. 96 1.1. Issues 98 This section lists a set of issues that need further investigation: 100 Discover ITRs: Current LISP design does not allow to automatically 101 discover active ITRs of a LISP domain (nor the mapping system of a 102 given domain is aware of ITRs of the same domain that can solicit 103 its services, let alone ITRs of other domains). The solution 104 proposed in this document allows to fill that gap. 106 Optimize EID-ROLC resolution time: Leaf LISP networks can be better 107 serviced, for example by avoiding the cascading of Map-Resolvers, 108 or by avoiding the solicitation of a Map-Resolver that is located 109 an ocean away, etc. Policies should be taken into account when 110 configuring Map-Resolver information on an ITR for improving EID- 111 to-RLOC resolution. These policies should be modified and 112 adjusted according to various events (e.g., installation of an 113 additional Map-Resolver). 115 Accomodate Map-Resolvers constraints: Allows for the protocol to 116 redirect a requesting ITR to another Map-Resolver when some events 117 occur, such as an overload of the initially targeted Map-Resolver 118 or when Map-Resolvers are optimized to service a set of 119 destination EIDs, etc. 121 Faster Recovery of mapping entries: Whenever an ITR fails for some 122 reason, the faulty ITR needs to recover at least the list of 123 mappings for the most popular prefixes in a timely manner, in 124 particular. Policies for mapping entries (to be recovered) are 125 deployment-specific. 127 Receive push notifications: For LISP leaf networks that would need 128 to maintain an up-to-date mapping table for a set of destination 129 EIDs (or even the global mapping table) to avoid issues such as 130 the loss of a first packet or to optimize LISP forwarding delay 131 (and therefore the overall forwarding efficiency), a dynamic push 132 mechanism would be helpful. 134 1.2. Assumptions 136 This document makes the following assumptions: 138 o Various LISP players (network operators, service providers, etc.) 139 are likely to deploy and operate different LISP Mapping Systems. 140 Multiple Mapping Systems will therefore coexist for various 141 reasons, e.g., avoid country-centric governance, allow for 142 distinct technologies to implement the mapping service, business 143 opportunities, service innovation, etc. 145 o Interconnection between these Mapping Systems is required for the 146 sake of global connectivity and also to minimize the risk of 147 fragmenting the Internet. 149 o Mapping Services are supposed to be dimensioned to maintain a 150 global mapping database for the entire LISP-enabled Internet. 152 o Mapping Service providers may offer advanced services to their 153 customers such as maintain local caches (a la CDN), or update ITR 154 mapping entries that match some criteria requested by a leaf LISP 155 network, redirect ITR requests to the closest Map-Resolvers, 156 structure the mapping resolution service so that the resolution 157 time is optimized, etc. 159 o The entries of the mapping tables are exchanged between these 160 Mapping systems so that Map-Request messages can be processed as 161 close to the LISP leaf networks as possible. 163 o A leaf LISP-enabled network subscribes to the Mapping Service 164 provided by one or several Mapping Service operators. 166 o The contribution of each player involved in the provisioning and 167 the operation of a LISP-based connectivity forwarding service 168 should be rationalized so that clear interfaces are defined and 169 adequate mechanisms for troubleshooting, diagnosis and repair 170 purposes can be easily implemented and adopted. The inability of 171 identifying what is at the origin of the degradation of a LISP 172 connectivity service is seen as one of the hurdles that are likely 173 to jeopardize LISP deployments at large scale. 175 1.3. Improving LISP Mapping Services 177 This document specifies a couple of additional LISP messages that are 178 meant to improve the subscription to Mapping Services, let alone 179 their serviceability. They are described in the following sections. 181 A simple method to redirect ITR-originated mapping requests towards 182 another Map-Resolver when some conditions are met (e.g., overload of 183 a Map-Resolver, enforcement of traffic engineering policies, etc.) is 184 defined in Section 2 and Section 3. 186 2. Map-Subscribe Message Format 188 The format of the Map-Subscribe message is shown in Figure 1. 190 0 1 2 3 191 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 1 192 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 193 |Type=15| Sub-type |A|U|B|I| Rsv | Filter Count | 194 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 195 | ITR Identifier | 196 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 197 | Nonce . . . | 198 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 199 | . . . Nonce | 200 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 201 | Key ID | Authentication Data Length | 202 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 203 ~ Authentication Data ~ 204 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 205 | Expiry Timer | 206 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 207 | Length | | 208 +-+-+-+-+-+-+-+-+ : 209 : Filter : 210 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 211 ... 212 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 213 | Length | | 214 +-+-+-+-+-+-+-+-+ : 215 : Filter : 216 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 218 Figure 1: Map-Subscribe Message Format 220 The description of the fields is as follows: 222 o Type MUST be set to 15 [RFC8113]. 224 o Sub-type: MUST be set to 1024. 226 o A (Ack-bit): this bit MUST be set to 0 for Map-Subscribe requests. 228 o U (unsolicited-map-reply bit): When set, this flag indicates that 229 the originating ITR is ready to receive implicit Map-Reply 230 messages. 232 o B (bulk-support bit): When set, this flag indicates that the 233 originating ITR supports mapping bulk retrieval method (e.g., 234 [I-D.boucadair-lisp-bulk]). 236 o I (immediate-retrieval bit): When set, this flag indicates that 237 the originating ITR requests immediate retrieval of the portion of 238 the mapping table that matches the filters included in the 239 request. 241 o Rsv: reserved bits, MUST be sent as 0 and MUST be ignored when 242 received. 244 o Filter Count: This field indicates the number of the filters 245 included in the message. 247 o Nonce, Key ID, Authentication Data Length, and Authentication Data 248 are similar to those of a LISP Map-Register message ([RFC6830]). 250 o Expiry Timer: This field indicates, in seconds, the validity timer 251 for the subscription. 253 o Length: This field indicates, in octets, the length of the filter 254 that is encoded in the "Filter" field. 256 o Filter: This field carries a destination EID (or a set thereof) 257 that is encoded as an UTF-8 string. This specification allows to 258 convey IP prefix literals, Names and/or AS numbers. One or 259 multiple filters may be present in a request. IPv4 prefixes are 260 encoded as IPv4-mapped IPv6 prefixes [RFC4291] (i.e., starting 261 with ::ffff:0:0/96). A mix of names, IP prefixes and AS numbers 262 may be enclosed in the same request. The value 0 is used to 263 delete existing filters. Filters MUST be applied in the order 264 they appear in the request. 266 3. Map-Subscribe-Ack Message Format 268 The format of the Map-Subscribe-Ack message is shown in Figure 2. 270 0 1 2 3 271 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 1 272 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 273 |Type=15| Sub-type |A|U|B|I|R| Rsv | Filter Count | 274 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 275 | ITR Identifier | 276 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 277 | Nonce . . . | 278 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 279 | . . . Nonce | 280 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 281 | Key ID | Authentication Data Length | 282 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 283 ~ Authentication Data ~ 284 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 285 | Expiry Timer | 286 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 287 | Length | | 288 +-+-+-+-+-+-+-+-+ : 289 : Filter : 290 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 291 ... 292 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 293 | Length | | 294 +-+-+-+-+-+-+-+-+ : 295 : Filter : 296 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 297 | | 298 | Redirect Map-Resolver | 299 | IP Address (128 bits) | 300 | | 301 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 303 Figure 2: Map-Subscribe-Ack Message Format 305 The description of the fields is as follows: 307 o Type: MUST be set to 15 [RFC8113]. 309 o Sub-type: MUST be set to 1024. 311 o A (Ack-bit): this bit MUST be set to 1 for Map-Subscribe-Ack 312 responses. 314 o U (unsolicited-map-reply bit): When set, this flag indicates that 315 the Map-Resolver can issue implicit Map-Reply messages. 317 o B (bulk-support bit): When set, this flag indicates that the Map- 318 Resolver supports mapping bulk retrieval method (e.g., 319 [I-D.boucadair-lisp-bulk]). 321 o I (immediate-retrieval bit): When set, this flag indicates that 322 the Map-Resolver will initiate an immediate push cycle of the 323 portion of the mapping table that matches the filters included in 324 the request. 326 o R (Redirect bit): When set, this flag indicates that a redirect 327 Map-Resolver is enclosed in the message. 329 o Rsv: reserved bits, MUST be set to 0 and MUST be ignored when 330 received. 332 o Result: indicates the result code of the processing of the Map- 333 Subscribe request. The following codes are defined: 335 0: SUCCESS. This code is used to indicate the request is 336 successfully processed. 338 1: PARTIAL-FILTERS-INSTALLED-LIMIT. This code is used to indicate 339 a request is successfully processed but some filters were not 340 installed because the number of filters carried in the initial 341 Map-Subscribe message exceeds the filter limit. 343 2: PARTIAL-FILTERS-INSTALLED-BAD. This code is used to indicate a 344 request is successfully processed but some filters were not 345 installed because they were malformed. 347 3: PARTIAL-FILTERS-INSTALLED-LOCAL. This code is used to indicate 348 a request is successfully processed but some filters were not 349 installed because of local reasons. The ITR SHOULD, after a 350 certain timer expires, send a Map-Subscribe request message for 351 the set of filters that are not included in the Map-Subscribe- 352 Ack message received by the ITR in response to its initial Map- 353 Subscribe request message. 355 4: FILTERS-PROHIBITED. This code is used to indicate a request is 356 successfully processed but the installation of filters is 357 prohibited. 359 o Filter Count: This field indicates the number of the filters 360 included in the message. 362 o Nonce, Key ID, Authentication Data Length, and Authentication Data 363 are similar to those of a LISP Map-Register message ([RFC6830]). 365 o Expiry Timer: This field indicates, in seconds, the validity timer 366 for the subscription. 368 o Length: This field indicates, in octets, the length of the filter 369 that is encoded in the "Filter" field. 371 o Filter: This field carries the set of filters that were 372 successfully installed. 374 o Redirect Map-Resolver IP Address (128 bits): When the R-bit is 375 set, this field carries the IP address of the Map-Resolver where 376 mapping requests should be redirected. An IPv4 address is encoded 377 as an IPv4-mapped IPv6 address. 379 4. Generating a Map-Subscribe Message 381 The A-bit of a Map-Subscribe message MUST be set to 0. 383 An ITR uses the U-bit to inform a Map-Resolver whether it is ready to 384 handle unsolicited Map-Reply messages or not. The ITR MUST set the 385 U-bit when it supports such capability. 387 An ITR uses the B-bit to inform a Map-Resolver whether it supports 388 the mapping bulk transfer method or not. The ITR MUST set to the 389 B-bit when it supports such method (e.g., [I-D.boucadair-lisp-bulk]). 391 An ITR that joins the LISP network is likely to delete all 392 notifications that are bound to its RLOCs. It does so by including a 393 Null filter prior to any filter that it wishes the Map-Resolver to 394 record. Note, an ITR can indicate a Null filter using one of these 395 methods: 397 1. Send a Map-Subscribe message with a "Filter Count" set to 0, or 399 2. Include a Filter with a 'Filter" field set to zeros. 401 An ITR that loses its mapping cache for some reason SHOULD generate a 402 Map-Subscribe message towards its Map-Resolver(s) with the I-bit set. 404 An ITR MAY generate several Map-Subscribe messages to make the Map- 405 Resolver install the required filters. Nevertheless, an ITR MUST 406 expect that the Map-Resolver may limit the number of filters that may 407 be installed. Filters that are not accepted or not processed by the 408 Map-Resolvers are not included in a Map-Subscribe-Ack message. 410 An ITR that wants to delete one or a set of filters MUST generate a 411 Map-Subscribe message which carries those filters with an Expiry 412 Timer set to 0. 414 5. Processing a Map-Subscribe Message 416 A Map-Resolver that does not support the Map-Subscribe message MUST 417 silently ignore any Map-Subscribe message it receives. 419 Map-Resolvers MUST support a configurable parameter to enable/disable 420 the processing of Map-Subscribe messages. The default value is set 421 to "enabled". 423 A Map-Resolver SHOULD support a configuration parameter to limit the 424 number of filters per leaf LISP network, per ITR, etc. 426 If a Map-Resolver receives a Map-Subscribe message and is enabled to 427 process it, a Map-Resolver MUST reply with a Map-Subscribe-Ack 428 message to acknowledge the receipt of the corresponding Map-Subscribe 429 message. 431 When building a Map-Subscribe-Ack message, the Map-Resolver MUST: 433 o Set the A-bit to indicate this is a response to a Map-Subscribe 434 request. 436 o Set the U-bit if it supports the unsolicited Map-Reply capability, 437 except if a redirect Map-Resolver is to be returned. 439 o Set the B-bit if it supports a method for mapping bulk transfer, 440 except if a redirect Map-Resolver is to be returned. 442 o Set the R-bit if it wants to inform the requesting ITR about 443 another Map-Resolver it should contact. The Map-Resolver MAY 444 return a set of filters that are to be applied by the ITR to 445 select the Map-Resolver (i.e., destination EID Map-Resolver 446 address selection). 448 o Echo the I-bit if the Map-Resolver accepts to initiate unsolicited 449 mapping retrievals, except if a redirect Map-Resolver is to be 450 returned. 452 o If no redirect is enabled and the request includes one or several 453 filters, the Map-Resolver MUST echo the filters it succeeds to 454 install, and in the same order of appearance, in the Map- 455 Subscribe-Ack message. 457 o If the Map-Resolver is configured with maximum and minimum values 458 for the expiry timer, the Map-Resolver MUST adjust the Expiry 459 Timer enclosed in the request so that it does not exceed these 460 boundary values. 462 If the I-bit is set in the Map-Subscribe request and the Map-Resolver 463 supports the unsolicited mapping retrieval capability, the Map- 464 Resolver SHOULD generate unsolicited Map-Reply messages or dedicated 465 bulk transfer messages that carry the EID-RLOC mapping entries that 466 match the filters already present in the Mapping System for that ITR 467 or that match those carried by the Map-Subscribe message. 469 If filters are included in the request, the Map-Resolver MUST extract 470 those filters and update its mapping system subscription for that ITR 471 accordingly. In particular, the Map-Resolver MUST delete all filters 472 that are active for that ITR if a Null filter is included in the Map- 473 Subscribe request or if the expiry timer is null. 475 If filters are not allowed for a given ITR, the 'Result' field MUST 476 be set to FILTERS-PROHIBITED. 478 If all filters are successfully installed, the 'Result' field MUST be 479 set to SUCCESS. 481 If the Map-Resolver fails to install some of the filters included in 482 a request because the filter limits for that ITR are exceeded, it 483 MUST NOT echo the corresponding filters in the Map-Subscribe-Ack 484 message. The 'Result' field MUST be set to PARTIAL-FILTERS- 485 INSTALLED-LIMIT. 487 If the Map-Resolver fails to install some of the filters included in 488 a request because these filters were malformed, it MUST NOT echo the 489 corresponding filters in the Map-Subscribe-Ack message; only 490 successfully installed filters MUST be included. The 'Result' field 491 MUST be set to PARTIAL-FILTERS-INSTALLED-BAD. 493 If, for some other reasons, the Map-Resolver fails to apply the 494 filters included in a request, it MUST NOT echo the said filters in 495 the Map-Subscribe-Ack message; only the successfully installed 496 filters MUST be included. The 'Result' field MUST be set to PARTIAL- 497 FILTERS-INSTALLED-LOCAL. 499 If a filter that is included in the request is more specific than a 500 filter that is already present in the mapping system for the same 501 ITR, the Map-Resolver MUST NOT add a new filter but MUST include the 502 old filter in the response to the requesting ITR. 504 If a more specific filter exists in the mapping system for the same 505 ITR, the Map-Resolver MUST replace the old filter (i.e., the one 506 already stored in the system) with the new filter (i.e., the one 507 included in the Map-Subscribe message). 509 An ITR can replace an existing filter by a more specific one by 510 deleting all filters and install the new ones. 512 A Map-Resolver that is overloaded or configured by means of a 513 specific policy to redirect requests sent by a set of ITRs to other 514 Map-Resolvers, the Map-Resolver MUST reply with a Map-Subscribe-Ack 515 message with the R-bit set and 'Redirect Map-Resolver IP Address' 516 field set to the redirect Map-Resolver'address. All other bit flags 517 MUST be returned unset. Moreover, the Expiry Timer MUST be set to 0. 518 No Filter MUST be included in the message. 520 If an event matches one of the filters that have been installed by an 521 ITR, the Map-Resolvers MUST generate the corresponding unsolicited 522 mapping update message (e.g., Map-Reply, mapping bulk method). 524 Upon expiry of the validity timer associated with a filter, the Map- 525 Resolver MUST delete that filter from its mapping subscription 526 system. 528 6. Processing a Map-Subscribe-Ack Message 530 Upon receipt of a Map-Subscribe-Ack message, the ITR MUST check 531 whether the message matches a Map-Subscribe message it sent to the 532 same Map-Resolver. If no matching state is found, the message MUST 533 be silently dropped. If a state is found, in addition to 534 authentication checks, the ITR MUST proceed as follows: 536 o If the U-bit is set, it should expect that unsolicited Map-Reply 537 messages will be received from this Map-Resolver. Appropriate 538 security mechanisms (e.g., Access Control Lists) SHOULD be 539 activated to allow the processing of these incoming unsolicited 540 Map-Reply messages. 542 o If the B-bit is set, it should expect that (unsolicited) mapping 543 bulk transfer messages are supported by this Map-Resolver. 544 Appropriate security mechanisms (e.g., Access Control Lists) 545 SHOULD be activated to allow the processing of these incoming 546 unsolicited bulk transfer messages. 548 o If the R-bit is set and the 'Redirect Map-Resolver IP Address' 549 field embeds a valid IP address, the ITR MUST update its Map- 550 Resolver contact information with the new Map-Resolver's IP 551 address. The ITR MUST use that IP address for subsequent 552 exchanges. Optionally, if filters were included in the reply sent 553 by the Map-Resolver, these filters are used for the destination 554 EID Map-Resolver address selection. 556 o If the message includes one or several filters, the ITR MUST check 557 whether the same set of filters as those included in the Map- 558 Subscribe request are carried in the Map-Subscribe-Ack message. 559 Filters that are not returned in the Map-Subscribe-Ack message may 560 not be valid or have exceeded a limit. The "Result" code 561 indicates the reason for not installing these filters. In 562 particular: 564 * An ITR that receives the result code set to PARTIAL-FILTERS- 565 INSTALLED-LIMIT MUST NOT try to install new filters unless it 566 clears all the filters maintained by the Map-Resolver or it 567 removes some of them. 569 * An ITR that receives the result code set to PARTIAL-FILTERS- 570 INSTALLED-BAD MUST NOT resend the same filters that were not 571 returned in the Map-Subscribe-Ack message, in subsequent Map- 572 Subscribe requests. 574 * An ITR that receives the result code set to FILTERS-PROHIBITED 575 MUST NOT include the filters that were not returned in the Map- 576 Subscribe-Ack message, in a Map-Subscribe message sent to that 577 Map-Resolver. 579 * An ITR that receives the result code set to PARTIAL-FILTERS- 580 INSTALLED-LOCAL SHOULD wait for at least 60 seconds before 581 issuing another Map-Subscribe message to install the filters 582 that were not returned in the Map-Subscribe-Ack message. 584 o The ITR MUST adjust the Expiry Timer carried in the Map-Subscribe- 585 Ack. Subscription should be renewed before the expiry of that 586 timer. 588 7. Subscription to Multiple Resolvers 590 In order to subscribe to multiple Map-Resolvers, an ITR sends Map- 591 Subscribe messages to a list of Map-Resolvers. Each of these 592 requests is handled as specified in Section 4. 594 8. Sample Examples 596 This section includes a set of examples to illustrate the usage of 597 the methods defined in Section 2. 599 8.1. Map-Resolver Redirect 601 The example shown in Figure 3, illustrates an example of an ITR 602 (ITR1) that is redirected to another Map-Resolver (MR2). 604 +--------+ +--------+ +--------+ 605 | ITR1 | | MR1 | | MR2 | 606 +--------+ +--------+ +--------+ 607 | | | 608 |Map-Subscribe | | 609 |-------------------------->| | 610 | Map-Subscribe-Ack (R, MR2)| | 611 |<--------------------------| | 612 |Map-Subscribe | | 613 |------------------------------------->| 614 | Map-Subscribe-Ack| 615 |<-------------------------------------| 616 | | 617 |Map-Request | 618 |------------------------------------->| 619 | Map-Reply| 620 |<-------------------------------------| 622 Figure 3: Example of Map-Resolver Redirection 624 8.2. Mapping Cache Retrieval 626 The examples shown in Figure 4 and Figure 5, illustrate examples of 627 an ITR (ITR1) that restores its mapping tables upon reboot according 628 to the filters already present in the mapping system. 630 The example in Figure 4, indicates how an ITR retrieves the mappings 631 that match the filters included in the Map-Subscribe request using 632 distinct Map-Reply messages. 634 The example in Figure 5, assumes that multiple records bound to 635 distinct EIDs are included in the same Map-Reply message. 637 This procedure applies to ITRs which do not store the mapping table 638 in a permanent memory storage facility. 640 Owing to this procedure, the ITR is ready-to-serve as soon as reboot 641 is completed or right after a mapping cache clear event. 643 +--------+ +--------+ 644 | ITR1 | | MR | 645 +--------+ +--------+ 646 | | 647 | | 648 |Map-Subscribe(d_EID, d_EID2,| 649 |..., d_EIDn) | 650 |--------------------------->| 651 | Map-Subscribe-Ack (d_EID,| 652 | d_EID2, ..., d_EIDn)| 653 |<---------------------------| 654 | | 655 <> 656 |Map-Subscribe(I) | 657 |--------------------------->| 658 | Map-Subscribe-Ack (I)| 659 |<---------------------------| 660 | Map-Reply (d_EID)| 661 |<---------------------------| 662 | Map-Reply (d_EID2)| 663 |<---------------------------| 664 .... 665 | Map-Reply (d_EIDn)| 666 |<---------------------------| 668 Figure 4: Example of Mapping Cache Retrieval: Matching the Filters 669 Installed in the Mapping System 671 +--------+ +--------+ 672 | ITR1 | | MR | 673 +--------+ +--------+ 674 | | 675 | | 676 |Map-Subscribe(d_EID, d_EID2,| 677 |..., d_EIDn) | 678 |--------------------------->| 679 | Map-Subscribe-Ack (d_EID,| 680 | d_EID2, ..., d_EIDn)| 681 |<---------------------------| 682 | | 683 <> 684 |Map-Subscribe(I) | 685 |--------------------------->| 686 | Map-Subscribe-Ack (I)| 687 |<---------------------------| 688 | Map-Reply (d_EID, d_EID2, 689 | ..., )| 690 |<---------------------------| 692 Figure 5: Example of Bulk Mapping Cache Retrieval: Matching the 693 Filters Installed in the Mapping System 695 8.3. Unsolicited Map-Reply 697 The example shown in Figure 6, illustrates an ITR (ITR1) that is 698 notified with the new EID-RLOC mapping that it subscribed to. 700 +--------+ +--------+ +--------+ 701 | ITR1 | | MR | | ETR | 702 +--------+ +--------+ +--------+ 703 | | | 704 | | | 705 |Map-Subscribe | | 706 |--------------------------->| | 707 | Map-Subscribe-Ack (d_EID)| | 708 |<---------------------------| | 709 | | | 710 | Map-Reply (d_EID)| | 711 |<---------------------------| | 712 .... 713 src=s_EID| | 714 -------->|src=RLOC_itr1 dst=RLOC_etr|src=s_EID 715 dst=d_EID|==============Encapsulated Packet==========>|--------> 716 | |dst=d_EID 717 .... 719 Figure 6: Example of Unsolicited Map-Reply 721 9. Security Considerations 723 This document does not introduce any additional security issues other 724 than those discussed in [RFC6830] and [RFC6833]. 726 10. IANA Considerations 728 This document requests IANA to assign a new code from the LISP Shared 729 Extension Message Type Sub-types ([RFC8113]): 731 Message Sub-type Reference 732 ================================= ======= =============== 733 Map-Subscribe/Map-Subscribe-Ack 1024 [This document] 735 11. Acknowledgments 737 This work is partly funded by ANR LISP-Lab project #ANR-13-INFR-009. 739 Many thanks to Stefano Secci and Chi-Dung Phung for their review. 741 12. References 742 12.1. Normative references 744 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 745 Requirement Levels", BCP 14, RFC 2119, 746 DOI 10.17487/RFC2119, March 1997, 747 . 749 [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing 750 Architecture", RFC 4291, DOI 10.17487/RFC4291, February 751 2006, . 753 [RFC6830] Farinacci, D., Fuller, V., Meyer, D., and D. Lewis, "The 754 Locator/ID Separation Protocol (LISP)", RFC 6830, 755 DOI 10.17487/RFC6830, January 2013, 756 . 758 [RFC6833] Fuller, V. and D. Farinacci, "Locator/ID Separation 759 Protocol (LISP) Map-Server Interface", RFC 6833, 760 DOI 10.17487/RFC6833, January 2013, 761 . 763 [RFC8113] Boucadair, M. and C. Jacquenet, "Locator/ID Separation 764 Protocol (LISP): Shared Extension Message & IANA Registry 765 for Packet Type Allocations", RFC 8113, 766 DOI 10.17487/RFC8113, March 2017, 767 . 769 12.2. Informative references 771 [I-D.boucadair-lisp-bulk] 772 Boucadair, M. and C. Jacquenet, "LISP Mapping Bulk 773 Retrieval", draft-boucadair-lisp-bulk-04 (work in 774 progress), February 2017. 776 Authors' Addresses 778 Mohamed Boucadair 779 Orange 780 Rennes 35000 781 France 783 EMail: mohamed.boucadair@orange.com 784 Christian Jacquenet 785 Orange 786 Rennes 35000 787 France 789 EMail: christian.jacquenet@orange.com