idnits 2.17.1 draft-kouvelas-lisp-map-server-reliable-transport-06.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (April 26, 2021) is 1096 days in the past. Is this intentional? Checking references for intended status: Experimental ---------------------------------------------------------------------------- == Missing Reference: 'RFC5925' is mentioned on line 771, but not defined == Missing Reference: 'RFC4895' is mentioned on line 772, but not defined == Unused Reference: 'RFC8060' is defined on line 826, but no explicit reference was found in the text == Outdated reference: A later version (-31) exists of draft-ietf-lisp-rfc6833bis-30 Summary: 0 errors (**), 0 flaws (~~), 5 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group J. Leong 3 Internet-Draft D. Lewis 4 Intended status: Experimental B. Pitta 5 Expires: October 28, 2021 Cisco Systems 6 C. Cassar 7 Tesla 8 I. Kouvelas 9 Arista Networks Inc. 10 J. Arango 11 Microsoft 12 April 26, 2021 14 LISP Map Server Reliable Transport 15 draft-kouvelas-lisp-map-server-reliable-transport-06 17 Abstract 19 The communication between LISP ETRs and Map-Servers is based on 20 unreliable UDP message exchange coupled with periodic message 21 transmission in order to maintain soft state. The drawback of 22 periodic messaging is the constant load imposed on both the ETR and 23 the Map-Server. New use cases for LISP have increased the amount of 24 state that needs to be communicated with requirements that are not 25 satisfied by the current mechanism. This document introduces the use 26 of a reliable transport for ETR to Map-Server communication in order 27 to eliminate the periodic messaging overhead, while providing 28 reliability, flow-control and endpoint liveness detection. 30 Status of This Memo 32 This Internet-Draft is submitted in full conformance with the 33 provisions of BCP 78 and BCP 79. 35 Internet-Drafts are working documents of the Internet Engineering 36 Task Force (IETF). Note that other groups may also distribute 37 working documents as Internet-Drafts. The list of current Internet- 38 Drafts is at https://datatracker.ietf.org/drafts/current/. 40 Internet-Drafts are draft documents valid for a maximum of six months 41 and may be updated, replaced, or obsoleted by other documents at any 42 time. It is inappropriate to use Internet-Drafts as reference 43 material or to cite them other than as "work in progress." 45 This Internet-Draft will expire on October 28, 2021. 47 Copyright Notice 49 Copyright (c) 2021 IETF Trust and the persons identified as the 50 document authors. All rights reserved. 52 This document is subject to BCP 78 and the IETF Trust's Legal 53 Provisions Relating to IETF Documents 54 (https://trustee.ietf.org/license-info) in effect on the date of 55 publication of this document. Please review these documents 56 carefully, as they describe your rights and restrictions with respect 57 to this document. Code Components extracted from this document must 58 include Simplified BSD License text as described in Section 4.e of 59 the Trust Legal Provisions and are provided without warranty as 60 described in the Simplified BSD License. 62 Table of Contents 64 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 65 2. Requirements Notation . . . . . . . . . . . . . . . . . . . . 3 66 3. Message Format . . . . . . . . . . . . . . . . . . . . . . . 4 67 4. Session Establishment . . . . . . . . . . . . . . . . . . . . 5 68 5. Error Notifications . . . . . . . . . . . . . . . . . . . . . 5 69 6. EID Prefix Registration . . . . . . . . . . . . . . . . . . . 7 70 6.1. Reliable Mapping Registration Messages . . . . . . . . . 7 71 6.1.1. Registration Message . . . . . . . . . . . . . . . . 8 72 6.1.2. Registration Acknowledgement Message . . . . . . . . 8 73 6.1.3. Registration Rejection Message . . . . . . . . . . . 9 74 6.1.4. Registration Refresh Message . . . . . . . . . . . . 10 75 6.1.5. Mapping Notification Message . . . . . . . . . . . . 12 76 6.2. ETR Behavior . . . . . . . . . . . . . . . . . . . . . . 13 77 6.3. Map-Server Behavior . . . . . . . . . . . . . . . . . . . 17 78 7. Security Considerations . . . . . . . . . . . . . . . . . . . 18 79 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 80 8.1. LISP Reliable Transport Message Types . . . . . . . . . . 18 81 8.2. Transport Protocol Port Numbers . . . . . . . . . . . . . 18 82 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 18 83 10. Normative References . . . . . . . . . . . . . . . . . . . . 19 84 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19 86 1. Introduction 88 The communication channel between LISP ETRs and Map-Servers is based 89 on unreliable UDP message exchange [I-D.ietf-lisp-rfc6833bis]. Where 90 required, reliability is pursued through periodic retransmissions 91 that maintain soft state on the peer. Map-Register messages are 92 retransmitted every minute by an ETR and the Map-Server times out its 93 state if the state is not refreshed for three successive periods. 94 When registering multiple EID-Prefixes, the ETR includes multiple 95 mapping records in the Map-Register message. Packet size limitations 96 provide an upper bound to the number of mapping records that can be 97 placed in each Map-Register message. When the ETR has more EID- 98 Prefixes to register than can be packed in a single Map-Register 99 message, the mapping records for the EID-Prefixes are split across 100 multiple Map-Register messages. 102 The drawback of the periodic registration is the constant load that 103 it introduces on both the ETR and the Map-Server. The ETR uses 104 resources to periodically build and transmit the Map-Register 105 messages, and to process the resulting Map-Notify messages issued by 106 the Map-Server. The Map-Server uses resources to process the 107 received Map-Register messages, update the corresponding registration 108 state, and build and transmit the matching Map-Notify messages. When 109 the number of EID-Prefixes to be registered by an ETR is small, the 110 resulting load imposed by periodic registrations may not be 111 significant. The ETR will only transmit a single Map-Register 112 message each period that contains a small number of mapping records. 114 In some LISP deployments, a large set of EID-Prefixes must be 115 registered by each ETR (e.g. mobility, database redistribution). Use 116 cases with a large set of EID-Prefixes behind an ETR will result in a 117 much higher load. An example is LISP mobility deployments where EID- 118 Prefixes are limited to host entries. ETRs may have thousands of 119 hosts to register resulting in hundreds of Map-Register and Map- 120 Notify messages per registration period. 122 A transport is required for the ETR to Map-Server communication that 123 provides reliability, flow-control and endpoint liveness 124 notifications. This document describes the use of TCP or SCTP as a 125 LISP reliable transport. The initial application for the LISP 126 reliable transport session is the support of scalable EID prefix 127 registration. The reliable session mechanism is defined to be 128 extensible so that it can support additional LISP communication 129 requirements as they arise using a single reliable transport session 130 between an ETR and a Map-Server. The use of the reliable transport 131 session for EID prefix registration is an alternative and does not 132 replace the existing UDP based mechanism. 134 2. Requirements Notation 136 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 137 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 138 document are to be interpreted as described in [RFC2119]. 140 3. Message Format 142 A single LISP reliable transport session may carry information for 143 multiple LISP applications. One such application is the registration 144 of EID to RLOC mappings that operates over a session between an ETR 145 and a Map-Server. Communication over a session is based on the 146 exchange of messages. This document defines a base set of messages 147 to support session establishment and management. It also defines the 148 messages for the EID to RLOC mapping registration application. 150 To support protocol extensibility when new applications, or 151 extensions to existing applications are introduced, the messages are 152 based on a TLV format. 154 0 1 2 3 155 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 1 156 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 157 | Type | Length | 158 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 159 | Message ID | 160 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 161 | Message Data ... 162 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 163 | Message End Marker | 164 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 166 Reliable transport message format 168 o Type: 16 bit type field identifying the message type. 170 o Length: 16 bit field that provides the total size of the message 171 in octets including the length, type and end marker fields. The 172 length allows the receiver to locate the next message in the TCP 173 stream. The minimum value of the length field is 8. 175 o ID: A 32-bit value that identifies the message. May be used by 176 the receiver to identify the message in replies or notification 177 messages. 179 o Data: Type specific message contents. 181 o End Marker: A 32-bit message end marker that must be set to 182 0x9FACADE9. The End Marker is used by the receiver to validate 183 that it has correctly parsed or skipped a message and provides a 184 method to detect formatting errors. Note that message data may 185 also contain this marker, and that the marker itself is not 186 sufficient for parsing the message. 188 The base message format does not indicate how the peer should deal 189 with the message in cases where the message type is not supported/ 190 understood. This is best dealt with by the application. For 191 example, in case an error notification is returned, or an expected 192 acknowledgement message is not received, the application might choose 193 various courses of action; from simply logging that the feature is 194 not supported, all the way to tearing the relationship with the peer 195 down for the feature, or for all LISP features. 197 4. Session Establishment 199 To ensure backwards compatibility, the map server and ETR MUST 200 communicate via unreliable UDP messages until a TCP session between 201 the two is successfully established. 203 The map server authenticates the ETR with the authentication data 204 contained in the first UDP map-register message it receives from the 205 ETR. Once the ETR is authenticated, the map server performs a 206 passive open by listening on TCP port 4342, and does not qualify the 207 remote port. As a security measure, the map server accepts TCP 208 connections only from those ETRs that have been authenticated via UDP 209 map-register messages. 211 The ETR assumes the active role of the TCP session establishment by 212 connecting to the map server once it has received a UDP map-notify 213 message. 215 When a TCP session goes down, UDP authentication must take place 216 before a new TCP session is established. The map-server will not 217 accept a connection from the ETR until a UDP map-register has been 218 received. Similarly, the ETR will not attempt to establish a session 219 with the map server until an UDP map-notify message has been 220 received. 222 A single reliable transport session is established between the map 223 server and the ETR to cover all communication needs. For example, an 224 ETR that has EID prefix registrations for multiple EID instances and 225 EID address families will only establish a single session with the 226 map server. 228 5. Error Notifications 230 The error notification message is used to communicate base reliable 231 transport session communication errors. LISP applications making use 232 of the reliable transport session and having to communicate 233 application specific errors must define their own messages to do so. 234 An error notification is issued when the receiver of a message does 235 not recognize the message type or cannot parse the message contents. 237 The notification includes the offending message type and ID and as 238 much of the offending message data as the notification sender wishes 239 to. 241 0 1 2 3 242 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 1 243 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 244 | Type = 16 | Length | 245 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 246 | Message ID | 247 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 248 | Error Code | Reserved | 249 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 250 | Offending Message Type | Offending Message Length | 251 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 252 | Offending Message ID | 253 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 254 | Offending Message Data ... 255 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 256 | Message End Marker | 257 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 259 Error Notification message format 261 o Error Code: An 8 bit field identifying the type of error that 262 occurred. Defined errors are: 264 * Unrecognized message type. 266 * Message format error. 268 o Reserved: Set to zero by the sender and ignored by the receiver. 270 o Offending Message Type: 16 bit type field identifying the message 271 type of the offending message that triggered this error 272 notification. This is copied from the Type field of the offending 273 message. 275 o Offending Message Length: 16 bit field that provides the total 276 size of the offending message in octets. This is copied from the 277 Length field of the offending message. 279 o Offending Message ID: A 32-bit field that is set to the Message ID 280 field of the offending message. 282 o Offending Message Data: The Data from the offending message that 283 triggered this error notification. The sender of the notification 284 may include as much of the original data as is deemed necessary. 286 The length of the Offending Message Data field is not provided by 287 the Offending Message Length field and is determined by 288 subtracting the size of the other fields in the message from the 289 Length field. It is valid to not include any of the offending 290 message data when sending an error notification. 292 o End Marker: A 32-bit message end marker that must be set to 293 0x9FACADE9. The End Marker is used by the receiver to validate 294 that it has correctly parsed or skipped a message and provides a 295 method to detect formatting errors. Note that message data may 296 also contain this marker, and that the marker itself is not 297 sufficient for parsing the message. 299 An error notification cannot be the offending message in another 300 error notification and MUST NOT trigger such a message. 302 6. EID Prefix Registration 304 EID prefix registration uses the reliable transport session between 305 an ETR and a Map-Server to communicate the ETR local EID database EID 306 to RLOC mappings to the Map-Server. In contrast to the UDP based 307 periodic registration, mapping information over the reliable 308 transport session is only sent when there is new information 309 available for the Map-Server. The Map-Server does not maintain a 310 timer to expire registrations communicated over the reliable 311 transport session. Instead an explicit de-registration (a 312 registration carrying a zero TTL) is needed to delete the state 313 maintained by the Map-Server. 315 The key used to identify registration mapping records in the ETR to 316 Map-Server communication is the EID prefix. The prefix may be 317 specified using an LCAF encoding that includes an EID instance ID. 319 When the reliable transport session goes down, registration mappings 320 learned by the Map-Server are treated as periodic UDP registrations 321 and a timer is used to expire them after 3 minutes. During this 322 period UDP based registrations or the re-establishment of the 323 reliable transport session and subsequent communication of a new 324 mapping can update the EID prefix mapping state. 326 6.1. Reliable Mapping Registration Messages 328 This section defines the LISP reliable transport session messages 329 used to communicate local EID database registrations between the ETR 330 and the Map-Server. 332 6.1.1. Registration Message 334 The reliable transport registration message is used to communicate 335 EID to RLOC mapping registrations from the ETR to the Map-Server. To 336 increase code reuse, the "Message Data" field uses the same format as 337 the UDP Map-Registers but without the IP and UDP headers. A reliable 338 registration message MUST contain a single mapping-record. The map 339 server MUST discard any reliable registration message that contains 340 more than one mapping record. 342 The reliable transport session is authenticated by means of the 343 session establishment procedure. Thus, although the Map-Register 344 MUST carry the authentication data, it is up to the map server to 345 determine if each individual reliable registration message should be 346 authenticated. 348 0 1 2 3 349 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 1 350 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 351 | Type = 17 | Length | 352 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 353 | Message ID | 354 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 355 | Map-Register message ... 356 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 357 ... Map-Register message | 358 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 359 | Message End Marker | 360 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 362 Registration message format 364 6.1.2. Registration Acknowledgement Message 366 The Acknowledgement message is sent from the Map-Server to the ETR to 367 confirm successful registration of an EID prefix previously 368 communicated by a reliable transport session Registration message. 369 The Registration Acknowledgement message does not carry a mapping 370 record (the map servers view of the mapping). This is accomplished 371 by the LISP reliable transport Map Notification message. 373 0 1 2 3 374 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 1 375 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 376 | Type = 18 | Length | 377 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 378 | Message ID | 379 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 380 | Prefix-Length | EID-Prefix-AFI | EID-Prefix ... 381 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 382 | Message End Marker | 383 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 385 Registration Acknowledgement message format 387 o Prefix-Length: Mask length for the EID prefix. 389 o EID-Prefix AFI: Address family identifier for the EID prefix in 390 the following field. 392 o EID-Prefix: The EID prefix from the received Registration. 394 6.1.3. Registration Rejection Message 396 The Registration Rejection Message is sent by the map server to the 397 ETR to indicate that the registration of a specific EID prefix is 398 being rejected or withdrawn. A rejection refers to a recently-sent 399 registration that is being immediately rejected. A withdrawal refers 400 to a previously accepted registration that is no longer acceptable, 401 perhaps due to a configuration change in the map-server. The ETR 402 must keep track of rejected EID prefixes and be prepared to re- 403 register their mappings when requested through a registration refresh 404 message. 406 0 1 2 3 407 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 1 408 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 409 | Type = 19 | Length | 410 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 411 | Message ID | 412 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 413 | Reason | Reserved | Prefix-Length | 414 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 415 | EID-Prefix-AFI | EID-Prefix ... 416 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 417 | Message End Marker | 418 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 420 Registration Rejection message format 422 o Reason: Code identifying the reason for which the Map-Server 423 rejected or withdrew the registration. 425 * 1 - Not a valid site EID prefix. 427 * 2 - Authentication failure. 429 * 3 - Locator set not allowed. 431 * 4 - Used to cover reason that's not defined. 433 o Reserved: This field is reserved for future use. Set to zero by 434 the sender and ignored by the receiver. 436 o Prefix-Length: Mask length for the EID prefix. 438 o EID-Prefix-AFI: Address family identifier for the EID prefix in 439 the following field. 441 o EID-Prefix: The EID prefix being rejected or withdrawn. 443 6.1.4. Registration Refresh Message 445 Sent by the Map-Server to the ETR to request the (re-)transmission of 446 EID prefix database mapping Registration messages. 448 0 1 2 3 449 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 1 450 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 451 | Type = 20 | Length | 452 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 453 | Message ID | 454 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 455 | Scope |R| Reserved | Prefix-Length | 456 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 457 | EID-Prefix-AFI | EID-Prefix ... 458 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 459 | Message End Marker | 460 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 462 Registration Refresh message format 464 o Scope: Determines the set of registrations being refreshed. 466 * 0 - All prefixes under all address families under all EID 467 instances are being refreshed. When using this scope the 468 Prefix-Length, EID-Prefix-AFI, and EID-Prefix fields MUST be 469 omitted. That is, the Message End Marker follows immediately 470 after the Reserved field. The total length of the message MUST 471 be 15 bytes. 473 * 1 - All prefixes under all address families under a single EID 474 instance are being refreshed. The Prefix-Length MUST be set to 475 zero, EID-Prefix-AFI MUST be set to LCAF type, the EID-Prefix 476 encodes the LCAF Instance ID, the LCAF address AFI MUST be set 477 to UNSPECIFIED. The total length of the message MUST be 30 478 bytes. 480 * 2 - All prefixes under a single address family under a single 481 EID instance are being refreshed. The Prefix-Length MUST be 482 set to zero, the EID-Prefix-AFI MUST be set to LCAF type and 483 the EID-Prefix MUST encode the Instance ID. The LCAF address 484 AFI MUST specify the address family to refresh, the actual 485 address SHOULD be set to zero. 487 * 3 - All prefixes covered by a specific EID prefix in a single 488 EID instance is being refreshed. The Prefix-Length, EID- 489 Prefix-AFI and EID prefix MUST be encoded accordingly. 491 * 4 - A specific EID prefix in a single EID instance is being 492 refreshed. The Prefix-Length, EID-Prefix-AFI and EID prefix 493 MUST be encoded accordingly. 495 The map-server has the flexibility to control the granularity of 496 the refresh by issuing refresh with different scopes. It can send 497 a single refresh with a coarse scope or send individual refreshes 498 with narrower scope. The ETR MUST be able to process all scopes 499 to ensure the map-server registration states are synchronized with 500 the ETR. 502 o R: Request from the ETR to only refresh registrations that have 503 been previously rejected by the Map-Server. If the R bit is set 504 then the scope cannot have a value of 3 and the EID-Prefix and 505 Prefix-Length fields must be omitted. 507 o Reserved: This field is reserved for future use. Set to zero by 508 the sender and ignored by the receiver. 510 o Prefix-Length: Mask length for the EID prefix. Refer to scope for 511 more details. 513 o EID-Prefix-AFI: Address family identifier for the EID prefix in 514 the following field. Refer to scope for more details. 516 o EID-Prefix: The EID prefix being refreshed. Refer to scope for 517 more details. 519 6.1.5. Mapping Notification Message 521 Mapping Notification messages communicate the Map-Server view of the 522 mapping for an EID prefix and no longer serve as a registration 523 acknowledgement. Mapping Notifications do not need message level 524 authentication as they are received over a reliable transport session 525 to a known Map-Server. Note that reliable transport Mapping 526 Notification messages do not reuse the UDP Map-Notify message format. 528 0 1 2 3 529 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 1 530 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 531 | Type = 21 | Length | 532 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 533 | Message ID | 534 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 535 | xTR-ID 128 bits ... 536 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 537 | xTR-ID 128 bits ... 538 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 539 | xTR-ID 128 bits ... 540 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 541 | xTR-ID 128 bits | 542 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 543 | site-ID 64 bits ... 544 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 545 | site-ID 64 bits | 546 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 547 | Mapping Record ... 548 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 549 ... Mapping Record | 550 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 551 | Message End Marker | 552 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 554 Mapping Notification message format 556 o xTR-ID: xTR-ID taken from the last valid registration the map- 557 server received for the EID-prefix conveyed in the mapping record. 559 o site-ID: site-ID taken from the last valid registration the map- 560 server received for the EID-prefix conveyed in the mapping record. 562 o Mapping Record: Mapping record of the EID-prefix the map-server is 563 conveying to the ETR. 565 6.2. ETR Behavior 567 The ETR operates the following per EID prefix, per MS state machine 568 that defines the reliable transport EID prefix registration behavior. 570 There are five states: 572 o No state: The local EID database prefix does not exist. 574 o Periodic: The local EID database prefix is being periodically 575 registered through UDP Map-Register messages as specified in []. 577 o Stable: From the ETR's perspective, no registrations are due to be 578 sent to the peer. The session to the peer is up, and the peer has 579 either acknowledged the registration, or is expected to request a 580 refresh in the future. 582 o AckWait: A Registration message for the prefix has been 583 transmitted to the Map-Server and the ETR is waiting for either a 584 Registration Acknowledge or Registration Rejected reply from the 585 Map-Server. 587 o Reject: The reliable transport registration for the local EID 588 database prefix was rejected by the Map-Server. From the ETR's 589 perspective, no registration is due to the peer AND the peer is 590 known to have rejected the registration. 592 The following events drive the state transitions: 594 o DB creation: The local EID database entry for the EID prefix is 595 created. 597 o DB deletion: The local EID database entry for the EID prefix is 598 deleted. 600 o DB change: The mapping contents or authentication information for 601 the local EID database entry changes. 603 o Session up: The reliable transport session to the Map-Server is 604 established. 606 o Session down: The reliable transport session the Map-Server goes 607 down. 609 o Recv Refresh: A Registration refresh message is received from the 610 Map-Server. 612 o Recv ACK: A Registration Acknowledge message is received from the 613 Map-Server. 615 o Recv Rejected: A Registration Rejected message is received from 616 the Map-Server. 618 o Periodic timer: The timer that drives generation of periodic UDP 619 Map-Register messages fires. 621 The state machine is: 623 +--------------------+--------------------------------------+ 624 | | Prev State | 625 | Event +-------------------+------------------+ 626 | | No state | Periodic | 627 +--------------------+-------------------+------------------+ 628 | DB creation | -> Periodic | N/A | 629 | [session down] | A1 | | 630 +--------------------+-------------------+------------------+ 631 | DB creation | -> AckWait | N/A | 632 | [session up] | A2 | | 633 +--------------------+-------------------+------------------+ 634 | DB deletion | N/A | -> No state | 635 | | | A3 | 636 +--------------------+-------------------+------------------+ 637 | DB change | N/A | - | 638 | | | A1 | 639 +--------------------+-------------------+------------------+ 640 | Session up | - | -> Stable | 641 | | | A4 | 642 +--------------------+-------------------+------------------+ 643 | Session down | - | N/A | 644 | | | | 645 +--------------------+-------------------+------------------+ 646 | Recv Refresh | - | N/A | 647 | | | | 648 +--------------------+-------------------+------------------+ 649 | Recv Refresh | - | N/A | 650 | [rejected] | | | 651 +--------------------+-------------------+------------------+ 652 | Recv ACK | - | N/A | 653 | | | | 654 +--------------------+-------------------+------------------+ 655 | Recv Rejection | - | N/A | 656 | | | | 657 +--------------------+-------------------+------------------+ 658 | Timer | N/A | - | 659 | | | A5 | 660 +--------------------+-------------------+------------------+ 662 xTR per EID prefix per MS state machine 664 +-----------------+-----------------------------------------------+ 665 | | Prev State | 666 | Event +---------------+---------------+---------------+ 667 | | Stable | AckWait | Rejected | 668 +-----------------+---------------+---------------+---------------+ 669 | DB creation | N/A | N/A | N/A | 670 | | | | | 671 +-----------------+---------------+---------------+---------------+ 672 | DB deletion | -> No state | -> No state | -> No state | 673 | | A6 | A6 | | 674 +-----------------+---------------+---------------+---------------+ 675 | DB change | -> AckWait | - | -> AckWait | 676 | | A2 | A2 | A2 | 677 +-----------------+---------------+---------------+---------------+ 678 | Session up | N/A | N/A | N/A | 679 | | | | | 680 +-----------------+---------------+---------------+---------------+ 681 | Session down | -> Periodic | -> Periodic | -> Periodic | 682 | | A7 | A7 | A7 | 683 +-----------------+---------------+---------------+---------------+ 684 | Recv Refresh | -> AckWait | - | -> AckWait | 685 | | A2 | A2 | A2 | 686 +-----------------+---------------+---------------+---------------+ 687 | Recv Refresh | - | - | -> AckWait | 688 | [rejected] | | A2 | A2 | 689 +-----------------+---------------+---------------+---------------+ 690 | Recv ACK | - | -> Stable | -> AckWait | 691 | | | | A2 | 692 +-----------------+---------------+---------------+---------------+ 693 | Recv Rejection | -> Rejected | -> Rejected | - | 694 | | | | | 695 +-----------------+---------------+---------------+---------------+ 696 | Timer | N/A | N/A | N/A | 697 | | | | | 698 +-----------------+---------------+---------------+---------------+ 700 xTR per EID prefix per MS state machine 702 Action descriptions: 704 o A1: Start periodic registration timer with zero delay. 706 o A2: Send Registration over reliable transport session. 708 o A3: Send UDP registration with zero TTL. 710 o A4: Stop periodic registration timer. 712 o A7: Send UDP registration and start periodic registration timer 713 with registration period. 715 o A6: Send Registration with TTL zero over reliable transport 716 session. 718 o A7: Start periodic registration timer with registration period. 720 All timer start actions must be jittered. 722 When the reliable transport session is established the ETR moves the 723 state machine into the Stable state without first registering the EID 724 prefix over the reliable transport session. The map server will send 725 a refresh message with a scope of 0 that will trigger the 726 registration message to be sent. Because other applications may be 727 using the reliable session, the refresh message signals the ETR that 728 the map server supports reliable map registration messages. This 729 model will also allow future optimizations where the Map-Server may 730 retain registration state from a previous instantiation of the 731 reliable transport session with the ETR and only request the refresh 732 of EID prefix state beyond some negotiated session progress marker. 734 Aa Map-Server authentication key change is treated as a DB change 735 event and will result in triggering a new Registration message to be 736 transmitted. 738 6.3. Map-Server Behavior 740 Received registrations create/update or delete mapping state. 742 A refresh with global scope is sent when a session between the ETR 743 and map-server is first established so the map-server can obtain the 744 complete database contents from the ETR. This refresh is also 745 serving as a capability signaling from the map-server to the ETR that 746 it can support reliable registration. 748 Refresh for rejected registrations sent (R bit set) when a new EID 749 prefix is configured on the Map-Server. 751 Refresh is sent whenever authentication key is changed or EID prefix 752 is deconfigured. Upon reception of the registration map-server can 753 decide whether to acknowledge the registration or issue rejection. 755 Mapping Notification message sent whenever the mapping for a 756 registered or more specific prefix for which notifications are 757 requested changes. ETR acknowledgement or rejection messaging for 758 Mapping Notification is not required because the ETR decides how to 759 process the message based on the registered mapping information. If 760 the mapping information changes the resulting registration will 761 trigger a new Mapping Notification message from the Map-Server. 763 7. Security Considerations 765 The LISP reliable transport session SHOULD be authenticated. On 766 controlled RLOC networks that can guarantee that the source RLOC 767 address of data packets cannot be spoofed, the authentication check 768 can be a source address validation on the reliable transport packets. 769 When the RLOC network does not provide such guarantees, reliable 770 transport authentication SHOULD be used. Implementations SHOULD 771 support the TCP Authentication Option (TCP-AO) [RFC5925] and SCTP 772 Authenticated Chunks [RFC4895]. 774 8. IANA Considerations 776 8.1. LISP Reliable Transport Message Types 778 Assignment of new LISP reliable transport message types is done 779 according to the "IETF Review" model defined in [RFC5266]. 781 The initial content of the registry should be as follows. 783 Type Name Reference 784 ----------- ---------------------------------------- -------------- 785 0-15 Reserved This document 786 16 Error Notification This document 787 17 Registration Message This document 788 18 Registration Acknowledgement Message This document 789 19 Registration Rejected Message This document 790 20 Registration Refresh Message This document 791 21 Mapping Notification Message This document 792 22-30 Reserved for EID membership distribution TBD 793 31-64999 Unassigned 794 65000-65535 Reserved for Experimental Use 796 8.2. Transport Protocol Port Numbers 798 TCP port 4342 already reserved for LISP CONS that is now obsolete. 799 Repurpose for reliable transport over TCP. Reserve an SCTP port. 801 9. Acknowledgments 803 The authors would like to thank Noel Chiappa, Dino Farinacci, Jesper 804 Skriver, Andre Pelletier and Les Ginsberg for their contributions to 805 this document. 807 10. Normative References 809 [I-D.ietf-lisp-rfc6833bis] 810 Farinacci, D., Maino, F., Fuller, V., and A. Cabellos- 811 Aparicio, "Locator/ID Separation Protocol (LISP) Control- 812 Plane", draft-ietf-lisp-rfc6833bis-30 (work in progress), 813 November 2020. 815 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 816 Requirement Levels", BCP 14, RFC 2119, 817 DOI 10.17487/RFC2119, March 1997, 818 . 820 [RFC5266] Devarapalli, V. and P. Eronen, "Secure Connectivity and 821 Mobility Using Mobile IPv4 and IKEv2 Mobility and 822 Multihoming (MOBIKE)", BCP 136, RFC 5266, 823 DOI 10.17487/RFC5266, June 2008, 824 . 826 [RFC8060] Farinacci, D., Meyer, D., and J. Snijders, "LISP Canonical 827 Address Format (LCAF)", RFC 8060, DOI 10.17487/RFC8060, 828 February 2017, . 830 Authors' Addresses 832 Johnson Leong 833 Cisco Systems 834 Tasman Drive 835 San Jose, CA 95134 836 USA 838 Email: joleong@cisco.com 840 Darrel Lewis 841 Cisco Systems 842 Tasman Drive 843 San Jose, CA 95134 844 USA 846 Email: darlewis@cisco.com 847 Balaji Pitta 848 Cisco Systems 849 Tasman Drive 850 San Jose, CA 95134 851 USA 853 Email: bvenkata@cisco.com 855 Chris Cassar 856 Tesla 857 10 New Square Park 858 Bedfont Lakes, Feltham TW14 8HA 859 United Kingdom 861 Email: christiancassar@acm.org 863 Isidor Kouvelas 864 Arista Networks Inc. 865 5453 Great America Parkway 866 Santa Clara, CA 95054 867 USA 869 Email: isidor@kouvelas.net 871 Jesus Arango 872 Microsoft 874 Email: jearango@microsoft.com