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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group D. Farinacci 3 Internet-Draft lispers.net 4 Obsoletes: 6830 (if approved) V. Fuller 5 Intended status: Standards Track vaf.net Internet Consulting 6 Expires: November 3, 2022 D. Meyer 7 1-4-5.net 8 D. Lewis 9 Cisco Systems 10 A. Cabellos (Ed.) 11 UPC/BarcelonaTech 12 May 2, 2022 14 The Locator/ID Separation Protocol (LISP) 15 draft-ietf-lisp-rfc6830bis-37 17 Abstract 19 This document describes the Data-Plane protocol for the Locator/ID 20 Separation Protocol (LISP). LISP defines two namespaces, End-point 21 Identifiers (EIDs) that identify end-hosts and Routing Locators 22 (RLOCs) that identify network attachment points. With this, LISP 23 effectively separates control from data, and allows routers to create 24 overlay networks. LISP-capable routers exchange encapsulated packets 25 according to EID-to-RLOC mappings stored in a local Map-Cache. 27 LISP requires no change to either host protocol stacks or to underlay 28 routers and offers Traffic Engineering, multihoming and mobility, 29 among other features. 31 This document obsoletes RFC 6830. 33 Status of This Memo 35 This Internet-Draft is submitted in full conformance with the 36 provisions of BCP 78 and BCP 79. 38 Internet-Drafts are working documents of the Internet Engineering 39 Task Force (IETF). Note that other groups may also distribute 40 working documents as Internet-Drafts. The list of current Internet- 41 Drafts is at https://datatracker.ietf.org/drafts/current/. 43 Internet-Drafts are draft documents valid for a maximum of six months 44 and may be updated, replaced, or obsoleted by other documents at any 45 time. It is inappropriate to use Internet-Drafts as reference 46 material or to cite them other than as "work in progress." 48 This Internet-Draft will expire on November 3, 2022. 50 Copyright Notice 52 Copyright (c) 2022 IETF Trust and the persons identified as the 53 document authors. All rights reserved. 55 This document is subject to BCP 78 and the IETF Trust's Legal 56 Provisions Relating to IETF Documents 57 (https://trustee.ietf.org/license-info) in effect on the date of 58 publication of this document. Please review these documents 59 carefully, as they describe your rights and restrictions with respect 60 to this document. Code Components extracted from this document must 61 include Simplified BSD License text as described in Section 4.e of 62 the Trust Legal Provisions and are provided without warranty as 63 described in the Simplified BSD License. 65 Table of Contents 67 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 68 1.1. Scope of Applicability . . . . . . . . . . . . . . . . . 4 69 2. Requirements Notation . . . . . . . . . . . . . . . . . . . . 5 70 3. Definition of Terms . . . . . . . . . . . . . . . . . . . . . 5 71 4. Basic Overview . . . . . . . . . . . . . . . . . . . . . . . 8 72 4.1. Deployment on the Public Internet . . . . . . . . . . . . 10 73 4.2. Packet Flow Sequence . . . . . . . . . . . . . . . . . . 11 74 5. LISP Encapsulation Details . . . . . . . . . . . . . . . . . 13 75 5.1. LISP IPv4-in-IPv4 Header Format . . . . . . . . . . . . . 13 76 5.2. LISP IPv6-in-IPv6 Header Format . . . . . . . . . . . . . 14 77 5.3. Tunnel Header Field Descriptions . . . . . . . . . . . . 15 78 6. LISP EID-to-RLOC Map-Cache . . . . . . . . . . . . . . . . . 20 79 7. Dealing with Large Encapsulated Packets . . . . . . . . . . . 20 80 7.1. A Stateless Solution to MTU Handling . . . . . . . . . . 21 81 7.2. A Stateful Solution to MTU Handling . . . . . . . . . . . 22 82 8. Using Virtualization and Segmentation with LISP . . . . . . . 23 83 9. Routing Locator Selection . . . . . . . . . . . . . . . . . . 23 84 10. Routing Locator Reachability . . . . . . . . . . . . . . . . 25 85 10.1. Echo Nonce Algorithm . . . . . . . . . . . . . . . . . . 27 86 11. EID Reachability within a LISP Site . . . . . . . . . . . . . 28 87 12. Routing Locator Hashing . . . . . . . . . . . . . . . . . . . 28 88 13. Changing the Contents of EID-to-RLOC Mappings . . . . . . . . 30 89 13.1. Locator-Status-Bits . . . . . . . . . . . . . . . . . . 30 90 13.2. Database Map-Versioning . . . . . . . . . . . . . . . . 30 91 14. Multicast Considerations . . . . . . . . . . . . . . . . . . 31 92 15. Router Performance Considerations . . . . . . . . . . . . . . 32 93 16. Security Considerations . . . . . . . . . . . . . . . . . . . 33 94 17. Network Management Considerations . . . . . . . . . . . . . . 34 95 18. Changes since RFC 6830 . . . . . . . . . . . . . . . . . . . 34 96 19. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 35 97 19.1. LISP UDP Port Numbers . . . . . . . . . . . . . . . . . 35 99 20. References . . . . . . . . . . . . . . . . . . . . . . . . . 35 100 20.1. Normative References . . . . . . . . . . . . . . . . . . 35 101 20.2. Informative References . . . . . . . . . . . . . . . . . 37 102 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 40 103 Appendix B. Document Change Log . . . . . . . . . . . . . . . . 41 104 B.1. Changes to draft-ietf-lisp-rfc6830bis-37 . . . . . . . . 41 105 B.2. Changes to draft-ietf-lisp-rfc6830bis-28 . . . . . . . . 41 106 B.3. Changes to draft-ietf-lisp-rfc6830bis-27 . . . . . . . . 41 107 B.4. Changes to draft-ietf-lisp-rfc6830bis-26 . . . . . . . . 42 108 B.5. Changes to draft-ietf-lisp-rfc6830bis-25 . . . . . . . . 42 109 B.6. Changes to draft-ietf-lisp-rfc6830bis-24 . . . . . . . . 42 110 B.7. Changes to draft-ietf-lisp-rfc6830bis-23 . . . . . . . . 42 111 B.8. Changes to draft-ietf-lisp-rfc6830bis-22 . . . . . . . . 42 112 B.9. Changes to draft-ietf-lisp-rfc6830bis-21 . . . . . . . . 42 113 B.10. Changes to draft-ietf-lisp-rfc6830bis-20 . . . . . . . . 42 114 B.11. Changes to draft-ietf-lisp-rfc6830bis-19 . . . . . . . . 43 115 B.12. Changes to draft-ietf-lisp-rfc6830bis-18 . . . . . . . . 43 116 B.13. Changes to draft-ietf-lisp-rfc6830bis-17 . . . . . . . . 43 117 B.14. Changes to draft-ietf-lisp-rfc6830bis-16 . . . . . . . . 43 118 B.15. Changes to draft-ietf-lisp-rfc6830bis-15 . . . . . . . . 43 119 B.16. Changes to draft-ietf-lisp-rfc6830bis-14 . . . . . . . . 43 120 B.17. Changes to draft-ietf-lisp-rfc6830bis-13 . . . . . . . . 44 121 B.18. Changes to draft-ietf-lisp-rfc6830bis-12 . . . . . . . . 44 122 B.19. Changes to draft-ietf-lisp-rfc6830bis-11 . . . . . . . . 44 123 B.20. Changes to draft-ietf-lisp-rfc6830bis-10 . . . . . . . . 44 124 B.21. Changes to draft-ietf-lisp-rfc6830bis-09 . . . . . . . . 44 125 B.22. Changes to draft-ietf-lisp-rfc6830bis-08 . . . . . . . . 45 126 B.23. Changes to draft-ietf-lisp-rfc6830bis-07 . . . . . . . . 45 127 B.24. Changes to draft-ietf-lisp-rfc6830bis-06 . . . . . . . . 45 128 B.25. Changes to draft-ietf-lisp-rfc6830bis-05 . . . . . . . . 46 129 B.26. Changes to draft-ietf-lisp-rfc6830bis-04 . . . . . . . . 46 130 B.27. Changes to draft-ietf-lisp-rfc6830bis-03 . . . . . . . . 46 131 B.28. Changes to draft-ietf-lisp-rfc6830bis-02 . . . . . . . . 46 132 B.29. Changes to draft-ietf-lisp-rfc6830bis-01 . . . . . . . . 46 133 B.30. Changes to draft-ietf-lisp-rfc6830bis-00 . . . . . . . . 47 134 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 47 136 1. Introduction 138 This document describes the Locator/Identifier Separation Protocol 139 (LISP). LISP is an encapsulation protocol built around the 140 fundamental idea of separating the topological location of a network 141 attachment point from the node's identity [CHIAPPA]. As a result 142 LISP creates two namespaces: Endpoint Identifiers (EIDs), that are 143 used to identify end-hosts (e.g., nodes or Virtual Machines) and 144 routable Routing Locators (RLOCs), used to identify network 145 attachment points. LISP then defines functions for mapping between 146 the two namespaces and for encapsulating traffic originated by 147 devices using non-routable EIDs for transport across a network 148 infrastructure that routes and forwards using RLOCs. LISP 149 encapsulation uses a dynamic form of tunneling where no static 150 provisioning is required or necessary. 152 LISP is an overlay protocol that separates control from Data-Plane, 153 this document specifies the Data-Plane as well as how LISP-capable 154 routers (Tunnel Routers) exchange packets by encapsulating them to 155 the appropriate location. Tunnel routers are equipped with a cache, 156 called Map-Cache, that contains EID-to-RLOC mappings. The Map-Cache 157 is populated using the LISP Control-Plane protocol 158 [I-D.ietf-lisp-rfc6833bis]. 160 LISP does not require changes to either the host protocol stack or to 161 underlay routers. By separating the EID from the RLOC space, LISP 162 offers native Traffic Engineering, multihoming and mobility, among 163 other features. 165 Creation of LISP was initially motivated by discussions during the 166 IAB-sponsored Routing and Addressing Workshop held in Amsterdam in 167 October 2006 (see [RFC4984]). 169 This document specifies the LISP Data-Plane encapsulation and other 170 LISP forwarding node functionality while [I-D.ietf-lisp-rfc6833bis] 171 specifies the LISP control plane. LISP deployment guidelines can be 172 found in [RFC7215] and [RFC6835] describes considerations for network 173 operational management. Finally, [I-D.ietf-lisp-introduction] 174 describes the LISP architecture. 176 This document obsoletes RFC 6830. 178 1.1. Scope of Applicability 180 LISP was originally developed to address the Internet-wide route 181 scaling problem [RFC4984]. While there are a number of approaches of 182 interest for that problem, as LISP as been developed and refined, a 183 large number of other LISP uses have been found and are being used. 184 As such, the design and development of LISP has changed so as to 185 focus on these use cases. The common property of these uses is a 186 large set of cooperating entities seeking to communicate over the 187 public Internet or other large underlay IP infrastructures, while 188 keeping the addressing and topology of the cooperating entities 189 separate from the underlay and Internet topology, routing, and 190 addressing. 192 2. Requirements Notation 194 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 195 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 196 "OPTIONAL" in this document are to be interpreted as described in BCP 197 14 [RFC2119] [RFC8174] when, and only when, they appear in all 198 capitals, as shown here. 200 3. Definition of Terms 202 Address Family Identifier (AFI): AFI is a term used to describe an 203 address encoding in a packet. An address family that pertains to 204 addresses found in Data-Plane headers. See [AFN] and [RFC3232] 205 for details. An AFI value of 0 used in this specification 206 indicates an unspecified encoded address where the length of the 207 address is 0 octets following the 16-bit AFI value of 0. 209 Anycast Address: Anycast Address refers to the same IPv4 or IPv6 210 address configured and used on multiple systems at the same time. 211 An EID or RLOC can be an anycast address in each of their own 212 address spaces. 214 Client-side: Client-side is a term used in this document to indicate 215 a connection initiation attempt by an end-system represented by an 216 EID. 218 Egress Tunnel Router (ETR): An ETR is a router that accepts an IP 219 packet where the destination address in the "outer" IP header is 220 one of its own RLOCs. The router strips the "outer" header and 221 forwards the packet based on the next IP header found. In 222 general, an ETR receives LISP-encapsulated IP packets from the 223 Internet on one side and sends decapsulated IP packets to site 224 end-systems on the other side. ETR functionality does not have to 225 be limited to a router device. A server host can be the endpoint 226 of a LISP tunnel as well. 228 EID-to-RLOC Database: The EID-to-RLOC Database is a distributed 229 database that contains all known EID-Prefix-to-RLOC mappings. 230 Each potential ETR typically contains a small piece of the 231 database: the EID-to-RLOC mappings for the EID-Prefixes "behind" 232 the router. These map to one of the router's own IP addresses 233 that are routable on the underlay. Note that there MAY be 234 transient conditions when the EID-Prefix for the LISP site and 235 Locator-Set for each EID-Prefix may not be the same on all ETRs. 236 This has no negative implications, since a partial set of Locators 237 can be used. 239 EID-to-RLOC Map-Cache: The EID-to-RLOC Map-Cache is generally 240 short-lived, on-demand table in an ITR that stores, tracks, and is 241 responsible for timing out and otherwise validating EID-to-RLOC 242 mappings. This cache is distinct from the full "database" of EID- 243 to-RLOC mappings; it is dynamic, local to the ITR(s), and 244 relatively small, while the database is distributed, relatively 245 static, and much more widely scoped to LISP nodes. 247 EID-Prefix: An EID-Prefix is a power-of-two block of EIDs that are 248 allocated to a site by an address allocation authority. EID- 249 Prefixes are associated with a set of RLOC addresses. EID-Prefix 250 allocations can be broken up into smaller blocks when an RLOC set 251 is to be associated with the larger EID-Prefix block. 253 End-System: An end-system is an IPv4 or IPv6 device that originates 254 packets with a single IPv4 or IPv6 header. The end-system 255 supplies an EID value for the destination address field of the IP 256 header when communicating outside of its routing domain. An end- 257 system can be a host computer, a switch or router device, or any 258 network appliance. 260 Endpoint ID (EID): An EID is a 32-bit (for IPv4) or 128-bit (for 261 IPv6) value that identifies a host. EIDs are generally only found 262 in the source and destination address fields of the first (most 263 inner) LISP header of a packet. The host obtains a destination 264 EID the same way it obtains a destination address today, for 265 example, through a Domain Name System (DNS) [RFC1034] lookup or 266 Session Initiation Protocol (SIP) [RFC3261] exchange. The source 267 EID is obtained via existing mechanisms used to set a host's 268 "local" IP address. An EID used on the public Internet MUST have 269 the same properties as any other IP address used in that manner; 270 this means, among other things, that it MUST be unique. An EID is 271 allocated to a host from an EID-Prefix block associated with the 272 site where the host is located. An EID can be used by a host to 273 refer to other hosts. Note that EID blocks MAY be assigned in a 274 hierarchical manner, independent of the network topology, to 275 facilitate scaling of the mapping database. In addition, an EID 276 block assigned to a site MAY have site-local structure 277 (subnetting) for routing within the site; this structure is not 278 visible to the underlay routing system. In theory, the bit string 279 that represents an EID for one device can represent an RLOC for a 280 different device. When used in discussions with other Locator/ID 281 separation proposals, a LISP EID will be called an "LEID". 282 Throughout this document, any references to "EID" refer to an 283 LEID. 285 Ingress Tunnel Router (ITR): An ITR is a router that resides in a 286 LISP site. Packets sent by sources inside of the LISP site to 287 destinations outside of the site are candidates for encapsulation 288 by the ITR. The ITR treats the IP destination address as an EID 289 and performs an EID-to-RLOC mapping lookup. The router then 290 prepends an "outer" IP header with one of its routable RLOCs (in 291 the RLOC space) in the source address field and the result of the 292 mapping lookup in the destination address field. Note that this 293 destination RLOC may be an intermediate, proxy device that has 294 better knowledge of the EID-to-RLOC mapping closer to the 295 destination EID. In general, an ITR receives IP packets from site 296 end-systems on one side and sends LISP-encapsulated IP packets 297 toward the Internet on the other side. 299 LISP Header: LISP header is a term used in this document to refer 300 to the outer IPv4 or IPv6 header, a UDP header, and a LISP- 301 specific 8-octet header that follow the UDP header and that an ITR 302 prepends or an ETR strips. 304 LISP Router: A LISP router is a router that performs the functions 305 of any or all of the following: ITR, ETR, RTR, Proxy-ITR (PITR), 306 or Proxy-ETR (PETR). 308 LISP Site: LISP site is a set of routers in an edge network that are 309 under a single technical administration. LISP routers that reside 310 in the edge network are the demarcation points to separate the 311 edge network from the core network. 313 Locator-Status-Bits (LSBs): Locator-Status-Bits are present in the 314 LISP header. They are used by ITRs to inform ETRs about the up/ 315 down status of all ETRs at the local site. These bits are used as 316 a hint to convey up/down router status and not path reachability 317 status. The LSBs can be verified by use of one of the Locator 318 reachability algorithms described in Section 10. An ETR MUST 319 rate-limit the action it takes when it detects changes in the 320 Locator-Status-Bits. 322 Proxy-ETR (PETR): A PETR is defined and described in [RFC6832]. A 323 PETR acts like an ETR but does so on behalf of LISP sites that 324 send packets to destinations at non-LISP sites. 326 Proxy-ITR (PITR): A PITR is defined and described in [RFC6832]. A 327 PITR acts like an ITR but does so on behalf of non-LISP sites that 328 send packets to destinations at LISP sites. 330 Recursive Tunneling: Recursive Tunneling occurs when a packet has 331 more than one LISP IP header. Additional layers of tunneling MAY 332 be employed to implement Traffic Engineering or other re-routing 333 as needed. When this is done, an additional "outer" LISP header 334 is added, and the original RLOCs are preserved in the "inner" 335 header. 337 Re-Encapsulating Tunneling Router (RTR): An RTR acts like an ETR to 338 remove a LISP header, then acts as an ITR to prepend a new LISP 339 header. This is known as Re-encapsulating Tunneling. Doing this 340 allows a packet to be re-routed by the RTR without adding the 341 overhead of additional tunnel headers. When using multiple 342 mapping database systems, care must be taken to not create re- 343 encapsulation loops through misconfiguration. 345 Route-Returnability: Route-returnability is an assumption that the 346 underlying routing system will deliver packets to the destination. 347 When combined with a nonce that is provided by a sender and 348 returned by a receiver, this limits off-path data insertion. A 349 route-returnability check is verified when a message is sent with 350 a nonce, another message is returned with the same nonce, and the 351 destination of the original message appears as the source of the 352 returned message. 354 Routing Locator (RLOC): An RLOC is an IPv4 [RFC0791] or IPv6 355 [RFC8200] address of an Egress Tunnel Router (ETR). An RLOC is 356 the output of an EID-to-RLOC mapping lookup. An EID maps to zero 357 or more RLOCs. Typically, RLOCs are numbered from blocks that are 358 assigned to a site at each point to which it attaches to the 359 underlay network; where the topology is defined by the 360 connectivity of provider networks. Multiple RLOCs can be assigned 361 to the same ETR device or to multiple ETR devices at a site. 363 Server-side: Server-side is a term used in this document to indicate 364 that a connection initiation attempt is being accepted for a 365 destination EID. 367 xTR: An xTR is a reference to an ITR or ETR when direction of data 368 flow is not part of the context description. "xTR" refers to the 369 router that is the tunnel endpoint and is used synonymously with 370 the term "Tunnel Router". For example, "An xTR can be located at 371 the Customer Edge (CE) router" indicates both ITR and ETR 372 functionality at the CE router. 374 4. Basic Overview 376 One key concept of LISP is that end-systems operate the same way they 377 do today. The IP addresses that hosts use for tracking sockets and 378 connections, and for sending and receiving packets, do not change. 379 In LISP terminology, these IP addresses are called Endpoint 380 Identifiers (EIDs). 382 Routers continue to forward packets based on IP destination 383 addresses. When a packet is LISP encapsulated, these addresses are 384 referred to as Routing Locators (RLOCs). Most routers along a path 385 between two hosts will not change; they continue to perform routing/ 386 forwarding lookups on the destination addresses. For routers between 387 the source host and the ITR as well as routers from the ETR to the 388 destination host, the destination address is an EID. For the routers 389 between the ITR and the ETR, the destination address is an RLOC. 391 Another key LISP concept is the "Tunnel Router". A Tunnel Router 392 prepends LISP headers on host-originated packets and strips them 393 prior to final delivery to their destination. The IP addresses in 394 this "outer header" are RLOCs. During end-to-end packet exchange 395 between two Internet hosts, an ITR prepends a new LISP header to each 396 packet, and an ETR strips the new header. The ITR performs EID-to- 397 RLOC lookups to determine the routing path to the ETR, which has the 398 RLOC as one of its IP addresses. 400 Some basic rules governing LISP are: 402 o End-systems only send to addresses that are EIDs. EIDs are 403 typically IP addresses assigned to hosts (other types of EID are 404 supported by LISP, see [RFC8060] for further information). End- 405 systems don't know that addresses are EIDs versus RLOCs but assume 406 that packets get to their intended destinations. In a system 407 where LISP is deployed, LISP routers intercept EID-addressed 408 packets and assist in delivering them across the network core 409 where EIDs cannot be routed. The procedure a host uses to send IP 410 packets does not change. 412 o LISP routers mostly deal with Routing Locator addresses. See 413 details in Section 4.2 to clarify what is meant by "mostly". 415 o RLOCs are always IP addresses assigned to routers, preferably 416 topologically oriented addresses from provider CIDR (Classless 417 Inter-Domain Routing) blocks. 419 o When a router originates packets, it MAY use as a source address 420 either an EID or RLOC. When acting as a host (e.g., when 421 terminating a transport session such as Secure SHell (SSH), 422 TELNET, or the Simple Network Management Protocol (SNMP)), it MAY 423 use an EID that is explicitly assigned for that purpose. An EID 424 that identifies the router as a host MUST NOT be used as an RLOC; 425 an EID is only routable within the scope of a site. A typical BGP 426 configuration might demonstrate this "hybrid" EID/RLOC usage where 427 a router could use its "host-like" EID to terminate iBGP sessions 428 to other routers in a site while at the same time using RLOCs to 429 terminate eBGP sessions to routers outside the site. 431 o Packets with EIDs in them are not expected to be delivered end-to- 432 end in the absence of an EID-to-RLOC mapping operation. They are 433 expected to be used locally for intra-site communication or to be 434 encapsulated for inter-site communication. 436 o EIDs MAY also be structured (subnetted) in a manner suitable for 437 local routing within an Autonomous System (AS). 439 An additional LISP header MAY be prepended to packets by a TE-ITR 440 when re-routing of the path for a packet is desired. A potential 441 use-case for this would be an ISP router that needs to perform 442 Traffic Engineering for packets flowing through its network. In such 443 a situation, termed "Recursive Tunneling", an ISP transit acts as an 444 additional ITR, and the destination RLOC it uses for the new 445 prepended header would be either a TE-ETR within the ISP (along an 446 intra-ISP traffic engineered path) or a TE-ETR within another ISP (an 447 inter-ISP traffic engineered path, where an agreement to build such a 448 path exists). 450 In order to avoid excessive packet overhead as well as possible 451 encapsulation loops, this document RECOMMENDS that a maximum of two 452 LISP headers can be prepended to a packet. For initial LISP 453 deployments, it is assumed that two headers is sufficient, where the 454 first prepended header is used at a site for Location/Identity 455 separation and the second prepended header is used inside a service 456 provider for Traffic Engineering purposes. 458 Tunnel Routers can be placed fairly flexibly in a multi-AS topology. 459 For example, the ITR for a particular end-to-end packet exchange 460 might be the first-hop or default router within a site for the source 461 host. Similarly, the ETR might be the last-hop router directly 462 connected to the destination host. Another example, perhaps for a 463 VPN service outsourced to an ISP by a site, the ITR could be the 464 site's border router at the service provider attachment point. 465 Mixing and matching of site-operated, ISP-operated, and other Tunnel 466 Routers is allowed for maximum flexibility. 468 4.1. Deployment on the Public Internet 470 Several of the mechanisms in this document are intended for 471 deployment in controlled, trusted environments, and are insecure for 472 use over the public Internet. In particular, on the public internet 473 xTRs: 475 o MUST set the N, L, E, and V bits in the LISP header (Section 5.1) 476 to zero. 478 o MUST NOT use Locator-Status-Bits and echo-nonce, as described in 479 Section 10 for Routing Locator Reachability. Instead MUST rely 480 solely on control-plane methods. 482 o MUST NOT use Gleaning or Locator-Status-Bits and Map-Versioning, 483 as described in Section 13 to update the EID-to-RLOC Mappings. 484 Instead relying solely on control-plane methods. 486 4.2. Packet Flow Sequence 488 This section provides an example of the unicast packet flow, 489 including also Control-Plane information as specified in 490 [I-D.ietf-lisp-rfc6833bis]. The example also assumes the following 491 conditions: 493 o Source host "host1.abc.example.com" is sending a packet to 494 "host2.xyz.example.com", exactly as it would if the site was not 495 not using LISP. 497 o Each site is multihomed, so each Tunnel Router has an address 498 (RLOC) assigned from the service provider address block for each 499 provider to which that particular Tunnel Router is attached. 501 o The ITR(s) and ETR(s) are directly connected to the source and 502 destination, respectively, but the source and destination can be 503 located anywhere in the LISP site. 505 o A Map-Request is sent for an external destination when the 506 destination is not found in the forwarding table or matches a 507 default route. Map-Requests are sent to the mapping database 508 system by using the LISP Control-Plane protocol documented in 509 [I-D.ietf-lisp-rfc6833bis]. 511 o Map-Replies are sent on the underlying routing system topology 512 using the [I-D.ietf-lisp-rfc6833bis] Control-Plane protocol. 514 Client host1.abc.example.com wants to communicate with server 515 host2.xyz.example.com: 517 1. host1.abc.example.com wants to open a TCP connection to 518 host2.xyz.example.com. It does a DNS lookup on 519 host2.xyz.example.com. An A/AAAA record is returned. This 520 address is the destination EID. The locally assigned address of 521 host1.abc.example.com is used as the source EID. An IPv4 or IPv6 522 packet is built and forwarded through the LISP site as a normal 523 IP packet until it reaches a LISP ITR. 525 2. The LISP ITR must be able to map the destination EID to an RLOC 526 of one of the ETRs at the destination site. A method to do this 527 is to send a LISP Map-Request, as specified in 528 [I-D.ietf-lisp-rfc6833bis]. 530 3. The mapping system helps forwarding the Map-Request to the 531 corresponding ETR. When the Map-Request arrives at one of the 532 ETRs at the destination site, it will process the packet as a 533 control message. 535 4. The ETR looks at the destination EID of the Map-Request and 536 matches it against the prefixes in the ETR's configured EID-to- 537 RLOC mapping database. This is the list of EID-Prefixes the ETR 538 is supporting for the site it resides in. If there is no match, 539 the Map-Request is dropped. Otherwise, a LISP Map-Reply is 540 returned to the ITR. 542 5. The ITR receives the Map-Reply message, parses the message, and 543 stores the mapping information from the packet. This information 544 is stored in the ITR's EID-to-RLOC Map-Cache. Note that the Map- 545 Cache is an on-demand cache. An ITR will manage its Map-Cache in 546 such a way that optimizes for its resource constraints. 548 6. Subsequent packets from host1.abc.example.com to 549 host2.xyz.example.com will have a LISP header prepended by the 550 ITR using the appropriate RLOC as the LISP header destination 551 address learned from the ETR. Note that the packet MAY be sent 552 to a different ETR than the one that returned the Map-Reply due 553 to the source site's hashing policy or the destination site's 554 Locator-Set policy. 556 7. The ETR receives these packets directly (since the destination 557 address is one of its assigned IP addresses), checks the validity 558 of the addresses, strips the LISP header, and forwards packets to 559 the attached destination host. 561 8. In order to defer the need for a mapping lookup in the reverse 562 direction, an ETR can OPTIONALLY create a cache entry that maps 563 the source EID (inner-header source IP address) to the source 564 RLOC (outer-header source IP address) in a received LISP packet. 565 Such a cache entry is termed a "glean mapping" and only contains 566 a single RLOC for the EID in question. More complete information 567 about additional RLOCs SHOULD be verified by sending a LISP Map- 568 Request for that EID. Both the ITR and the ETR MAY also 569 influence the decision the other makes in selecting an RLOC. 571 5. LISP Encapsulation Details 573 Since additional tunnel headers are prepended, the packet becomes 574 larger and can exceed the MTU of any link traversed from the ITR to 575 the ETR. It is RECOMMENDED in IPv4 that packets do not get 576 fragmented as they are encapsulated by the ITR. Instead, the packet 577 is dropped and an ICMP Unreachable/Fragmentation-Needed message is 578 returned to the source. 580 In the case when fragmentation is needed, this specification 581 RECOMMENDS that implementations provide support for one of the 582 proposed fragmentation and reassembly schemes. Two existing schemes 583 are detailed in Section 7. 585 Since IPv4 or IPv6 addresses can be either EIDs or RLOCs, the LISP 586 architecture supports IPv4 EIDs with IPv6 RLOCs (where the inner 587 header is in IPv4 packet format and the outer header is in IPv6 588 packet format) or IPv6 EIDs with IPv4 RLOCs (where the inner header 589 is in IPv6 packet format and the outer header is in IPv4 packet 590 format). The next sub-sections illustrate packet formats for the 591 homogeneous case (IPv4-in-IPv4 and IPv6-in-IPv6), but all 4 592 combinations MUST be supported. Additional types of EIDs are defined 593 in [RFC8060]. 595 As LISP uses UDP encapsulation to carry traffic between xTRs across 596 the Internet, implementors should be aware of the provisions of 597 [RFC8085], especially those given in section 3.1.11 on congestion 598 control for UDP tunneling. 600 Implementors are encouraged to consider UDP checksum usage guidelines 601 in section 3.4 of [RFC8085] when it is desirable to protect UDP and 602 LISP headers against corruption. 604 5.1. LISP IPv4-in-IPv4 Header Format 605 0 1 2 3 606 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 1 607 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 608 / |Version| IHL | DSCP |ECN| Total Length | 609 / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 610 | | Identification |Flags| Fragment Offset | 611 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 612 OH | Time to Live | Protocol = 17 | Header Checksum | 613 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 614 | | Source Routing Locator | 615 \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 616 \ | Destination Routing Locator | 617 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 618 / | Source Port = xxxx | Dest Port = 4341 | 619 UDP +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 620 \ | UDP Length | UDP Checksum | 621 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 622 L |N|L|E|V|I|R|K|K| Nonce/Map-Version | 623 I \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 624 S / | Instance ID/Locator-Status-Bits | 625 P +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 626 / |Version| IHL | DSCP |ECN| Total Length | 627 / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 628 | | Identification |Flags| Fragment Offset | 629 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 630 IH | Time to Live | Protocol | Header Checksum | 631 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 632 | | Source EID | 633 \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 634 \ | Destination EID | 635 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 637 IHL = IP-Header-Length 639 5.2. LISP IPv6-in-IPv6 Header Format 641 0 1 2 3 642 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 1 643 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 644 / |Version| DSCP |ECN| Flow Label | 645 / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 646 | | Payload Length | Next Header=17| Hop Limit | 647 v +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 648 | | 649 O + + 650 u | | 651 t + Source Routing Locator + 652 e | | 653 r + + 654 | | 655 H +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 656 d | | 657 r + + 658 | | 659 ^ + Destination Routing Locator + 660 | | | 661 \ + + 662 \ | | 663 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 664 / | Source Port = xxxx | Dest Port = 4341 | 665 UDP +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 666 \ | UDP Length | UDP Checksum | 667 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 668 L |N|L|E|V|I|R|K|K| Nonce/Map-Version | 669 I \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 670 S / | Instance ID/Locator-Status-Bits | 671 P +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 672 / |Version| DSCP |ECN| Flow Label | 673 / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 674 / | Payload Length | Next Header | Hop Limit | 675 v +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 676 | | 677 I + + 678 n | | 679 n + Source EID + 680 e | | 681 r + + 682 | | 683 H +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 684 d | | 685 r + + 686 | | 687 ^ + Destination EID + 688 \ | | 689 \ + + 690 \ | | 691 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 693 5.3. Tunnel Header Field Descriptions 695 Inner Header (IH): The inner header is the header on the 696 datagram received from the originating host [RFC0791] [RFC8200] 697 [RFC2474]. The source and destination IP addresses are EIDs. 699 Outer Header: (OH) The outer header is a new header prepended by an 700 ITR. The address fields contain RLOCs obtained from the ingress 701 router's EID-to-RLOC Cache. The IP protocol number is "UDP (17)" 702 from [RFC0768]. The setting of the Don't Fragment (DF) bit 703 'Flags' field is according to rules listed in Sections 7.1 and 704 7.2. 706 UDP Header: The UDP header contains an ITR selected source port when 707 encapsulating a packet. See Section 12 for details on the hash 708 algorithm used to select a source port based on the 5-tuple of the 709 inner header. The destination port MUST be set to the well-known 710 IANA-assigned port value 4341. 712 UDP Checksum: The 'UDP Checksum' field SHOULD be transmitted as zero 713 by an ITR for either IPv4 [RFC0768] and IPv6 encapsulation 714 [RFC6935] [RFC6936]. When a packet with a zero UDP checksum is 715 received by an ETR, the ETR MUST accept the packet for 716 decapsulation. When an ITR transmits a non-zero value for the UDP 717 checksum, it MUST send a correctly computed value in this field. 718 When an ETR receives a packet with a non-zero UDP checksum, it MAY 719 choose to verify the checksum value. If it chooses to perform 720 such verification, and the verification fails, the packet MUST be 721 silently dropped. If the ETR chooses not to perform the 722 verification, or performs the verification successfully, the 723 packet MUST be accepted for decapsulation. The handling of UDP 724 zero checksums over IPv6 for all tunneling protocols, including 725 LISP, is subject to the applicability statement in [RFC6936]. 727 UDP Length: The 'UDP Length' field is set for an IPv4-encapsulated 728 packet to be the sum of the inner-header IPv4 Total Length plus 729 the UDP and LISP header lengths. For an IPv6-encapsulated packet, 730 the 'UDP Length' field is the sum of the inner-header IPv6 Payload 731 Length, the size of the IPv6 header (40 octets), and the size of 732 the UDP and LISP headers. 734 N: The N-bit is the nonce-present bit. When this bit is set to 1, 735 the low-order 24 bits of the first 32 bits of the LISP header 736 contain a Nonce. See Section 10.1 for details. Both N- and 737 V-bits MUST NOT be set in the same packet. If they are, a 738 decapsulating ETR MUST treat the 'Nonce/Map-Version' field as 739 having a Nonce value present. 741 L: The L-bit is the 'Locator-Status-Bits' field enabled bit. When 742 this bit is set to 1, the Locator-Status-Bits in the second 743 32 bits of the LISP header are in use. 745 x 1 x x 0 x x x 746 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 747 |N|L|E|V|I|R|K|K| Nonce/Map-Version | 748 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 749 | Locator-Status-Bits | 750 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 752 E: The E-bit is the echo-nonce-request bit. This bit MUST be ignored 753 and has no meaning when the N-bit is set to 0. When the N-bit is 754 set to 1 and this bit is set to 1, an ITR is requesting that the 755 nonce value in the 'Nonce' field be echoed back in LISP- 756 encapsulated packets when the ITR is also an ETR. See 757 Section 10.1 for details. 759 V: The V-bit is the Map-Version present bit. When this bit is set to 760 1, the N-bit MUST be 0. Refer to the [I-D.ietf-lisp-6834bis] 761 specification for more details on Database Map-Versioning. This 762 bit indicates that the LISP header is encoded in this case as: 764 0 x 0 1 x x x x 765 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 766 |N|L|E|V|I|R|K|K| Source Map-Version | Dest Map-Version | 767 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 768 | Instance ID/Locator-Status-Bits | 769 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 771 I: The I-bit is the Instance ID bit. See Section 8 for more details. 772 When this bit is set to 1, the 'Locator-Status-Bits' field is 773 reduced to 8 bits and the high-order 24 bits are used as an 774 Instance ID. If the L-bit is set to 0, then the low-order 8 bits 775 are transmitted as zero and ignored on receipt. The format of the 776 LISP header would look like this: 778 x x x x 1 x x x 779 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 780 |N|L|E|V|I|R|K|K| Nonce/Map-Version | 781 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 782 | Instance ID | LSBs | 783 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 785 R: The R-bit is a Reserved and unassigned bit for future use. It 786 MUST be set to 0 on transmit and MUST be ignored on receipt. 788 KK: The KK-bits are a 2-bit field used when encapsulated packets are 789 encrypted. The field is set to 00 when the packet is not 790 encrypted. See [RFC8061] for further information. 792 LISP Nonce: The LISP 'Nonce' field is a 24-bit value that is 793 randomly generated by an ITR when the N-bit is set to 1. Nonce 794 generation algorithms are an implementation matter but are 795 required to generate different nonces when sending to different 796 RLOCs. The nonce is also used when the E-bit is set to request 797 the nonce value to be echoed by the other side when packets are 798 returned. When the E-bit is clear but the N-bit is set, a remote 799 ITR is either echoing a previously requested echo-nonce or 800 providing a random nonce. See Section 10.1 for more details. 801 Finally, when both the N and V-bit are not set (N=0, V=0), then 802 both the Nonce and Map-Version fields are set to 0 and ignored on 803 receipt. 805 LISP Locator-Status-Bits (LSBs): When the L-bit is also set, the 806 'Locator-Status-Bits' field in the LISP header is set by an ITR to 807 indicate to an ETR the up/down status of the Locators in the 808 source site. Each RLOC in a Map-Reply is assigned an ordinal 809 value from 0 to n-1 (when there are n RLOCs in a mapping entry). 810 The Locator-Status-Bits are numbered from 0 to n-1 from the least 811 significant bit of the field. The field is 32 bits when the I-bit 812 is set to 0 and is 8 bits when the I-bit is set to 1. When a 813 Locator-Status-Bit is set to 1, the ITR is indicating to the ETR 814 that the RLOC associated with the bit ordinal has up status. See 815 Section 10 for details on how an ITR can determine the status of 816 the ETRs at the same site. When a site has multiple EID-Prefixes 817 that result in multiple mappings (where each could have a 818 different Locator-Set), the Locator-Status-Bits setting in an 819 encapsulated packet MUST reflect the mapping for the EID-Prefix 820 that the inner-header source EID address matches (longest-match). 821 If the LSB for an anycast Locator is set to 1, then there is at 822 least one RLOC with that address, and the ETR is considered 'up'. 824 When doing ITR/PITR encapsulation: 826 o The outer-header 'Time to Live' field (or 'Hop Limit' field, in 827 the case of IPv6) SHOULD be copied from the inner-header 'Time to 828 Live' field. 830 o The outer-header IPv4 'Differentiated Services Code Point' (DSCP) 831 field or the 'Traffic Class' field, in the case of IPv6, SHOULD be 832 copied from the inner-header IPv4 DSCP field or 'Traffic Class' 833 field in the case of IPv6, to the outer-header. Guidelines for 834 this can be found at [RFC2983]. 836 o The IPv4 'Explicit Congestion Notification' (ECN) field and bits 6 837 and 7 of the IPv6 'Traffic Class' field requires special treatment 838 in order to avoid discarding indications of congestion as 839 specified in [RFC6040]. 841 When doing ETR/PETR decapsulation: 843 o The inner-header IPv4 'Time to Live' field or 'Hop Limit' field in 844 the case of IPv6, MUST be copied from the outer-header 'Time to 845 Live'/'Hop Limit' field, when the 'Time to Live'/'Hop Limit' value 846 of the outer header is less than the 'Time to Live'/'Hop Limit' 847 value of the inner header. Failing to perform this check can 848 cause the 'Time to Live'/'Hop Limit' of the inner header to 849 increment across encapsulation/decapsulation cycles. This check 850 is also performed when doing initial encapsulation, when a packet 851 comes to an ITR or PITR destined for a LISP site. 853 o The outer-header IPv4 'Differentiated Services Code Point' (DSCP) 854 field or the 'Traffic Class' field in the case of IPv6, SHOULD be 855 copied from the outer-header IPv4 DSCP field or 'Traffic Class' 856 field in the case of IPv6, to the inner-header. Guidelines for 857 this can be found at [RFC2983]. 859 o The IPv4 'Explicit Congestion Notification' (ECN) field and bits 6 860 and 7 of the IPv6 'Traffic Class' field, requires special 861 treatment in order to avoid discarding indications of congestion 862 as specified in [RFC6040]. Note that implementations exist that 863 copy the 'ECN' field from the outer header to the inner header 864 even though [RFC6040] does not recommend this behavior. It is 865 RECOMMENDED that implementations change to support the behavior in 866 [RFC6040]. 868 Note that if an ETR/PETR is also an ITR/PITR and chooses to re- 869 encapsulate after decapsulating, the net effect of this is that the 870 new outer header will carry the same Time to Live as the old outer 871 header minus 1. 873 Copying the Time to Live (TTL) serves two purposes: first, it 874 preserves the distance the host intended the packet to travel; 875 second, and more importantly, it provides for suppression of looping 876 packets in the event there is a loop of concatenated tunnels due to 877 misconfiguration. 879 Some xTRs and PxTRs performs re-encapsulation operations and need to 880 treat the 'Explicit Congestion Notification' (ECN) in a special way. 881 Because the re-encapsulation operation is a sequence of two 882 operations, namely a decapsulation followed by an encapsulation, the 883 ECN bits MUST be treated as described above for these two operations. 885 The LISP dataplane protocol is not backwards compatible with 886 [RFC6830] and does not have explicit support for introducing future 887 protocol changes (e.g. an explicit version field). However, the LISP 888 control plane [I-D.ietf-lisp-rfc6833bis] allows an ETR to register 889 dataplane capabilities by means of new LCAF types [RFC8060]. In this 890 way an ITR can be made aware of the dataplane capabilities of an ETR, 891 and encapsulate accordingly. The specification of the new LCAF 892 types, new LCAF mechanisms, and their use, is out of the scope of 893 this document. 895 6. LISP EID-to-RLOC Map-Cache 897 ITRs and PITRs maintain an on-demand cache, referred as LISP EID-to- 898 RLOC Map-Cache, that contains mappings from EID-prefixes to locator 899 sets. The cache is used to encapsulate packets from the EID space to 900 the corresponding RLOC network attachment point. 902 When an ITR/PITR receives a packet from inside of the LISP site to 903 destinations outside of the site a longest-prefix match lookup of the 904 EID is done to the Map-Cache. 906 When the lookup succeeds, the Locator-Set retrieved from the Map- 907 Cache is used to send the packet to the EID's topological location. 909 If the lookup fails, the ITR/PITR needs to retrieve the mapping using 910 the LISP Control-Plane protocol [I-D.ietf-lisp-rfc6833bis]. While 911 the mapping is being retrieved, the ITR/PITR can either drop or 912 buffer the packets. This document does not have specific 913 recommendations about the action to be taken. It is up to the 914 deployer to consider whether or not it is desirable to buffer packets 915 and deploy a LISP implementation that offers the desired behaviour. 916 Once the mapping is resolved it is then stored in the local Map-Cache 917 to forward subsequent packets addressed to the same EID-prefix. 919 The Map-Cache is a local cache of mappings, entries are expired based 920 on the associated Time to live. In addition, entries can be updated 921 with more current information, see Section 13 for further information 922 on this. Finally, the Map-Cache also contains reachability 923 information about EIDs and RLOCs, and uses LISP reachability 924 information mechanisms to determine the reachability of RLOCs, see 925 Section 10 for the specific mechanisms. 927 7. Dealing with Large Encapsulated Packets 929 This section proposes two mechanisms to deal with packets that exceed 930 the path MTU between the ITR and ETR. 932 It is left to the implementor to decide if the stateless or stateful 933 mechanism SHOULD be implemented. Both or neither can be used, since 934 it is a local decision in the ITR regarding how to deal with MTU 935 issues, and sites can interoperate with differing mechanisms. 937 Both stateless and stateful mechanisms also apply to Re-encapsulating 938 and Recursive Tunneling, so any actions below referring to an ITR 939 also apply to a TE-ITR. 941 7.1. A Stateless Solution to MTU Handling 943 An ITR stateless solution to handle MTU issues is described as 944 follows: 946 1. Define H to be the size, in octets, of the outer header an ITR 947 prepends to a packet. This includes the UDP and LISP header 948 lengths. 950 2. Define L to be the size, in octets, of the maximum-sized packet 951 an ITR can send to an ETR without the need for the ITR or any 952 intermediate routers to fragment the packet. The network 953 administrator of the LISP deployment has to determine what is the 954 suitable value of L so to make sure that no MTU issues arise. 956 3. Define an architectural constant S for the maximum size of a 957 packet, in octets, an ITR MUST receive from the source so the 958 effective MTU can be met. That is, L = S + H. 960 When an ITR receives a packet from a site-facing interface and adds H 961 octets worth of encapsulation to yield a packet size greater than L 962 octets (meaning the received packet size was greater than S octets 963 from the source), it resolves the MTU issue by first splitting the 964 original packet into 2 equal-sized fragments. A LISP header is then 965 prepended to each fragment. The size of the encapsulated fragments 966 is then (S/2 + H), which is less than the ITR's estimate of the path 967 MTU between the ITR and its correspondent ETR. 969 When an ETR receives encapsulated fragments, it treats them as two 970 individually encapsulated packets. It strips the LISP headers and 971 then forwards each fragment to the destination host of the 972 destination site. The two fragments are reassembled at the 973 destination host into the single IP datagram that was originated by 974 the source host. Note that reassembly can happen at the ETR if the 975 encapsulated packet was fragmented at or after the ITR. 977 This behavior MUST be performed by the ITR only when the source host 978 originates a packet with the 'DF' field of the IP header set to 0. 979 When the 'DF' field of the IP header is set to 1, or the packet is an 980 IPv6 packet originated by the source host, the ITR will drop the 981 packet when the size (adding in the size of the encapsulation header) 982 is greater than L and send an ICMPv4 ICMP Unreachable/Fragmentation- 983 Needed or ICMPv6 "Packet Too Big" message to the source with a value 984 of S, where S is (L - H). 986 When the outer-header encapsulation uses an IPv4 header, an 987 implementation SHOULD set the DF bit to 1 so ETR fragment reassembly 988 can be avoided. An implementation MAY set the DF bit in such headers 989 to 0 if it has good reason to believe there are unresolvable path MTU 990 issues between the sending ITR and the receiving ETR. 992 This specification RECOMMENDS that L be defined as 1500. Additional 993 information about in-network MTU and fragmentation issues can be 994 found at [RFC4459]. 996 7.2. A Stateful Solution to MTU Handling 998 An ITR stateful solution to handle MTU issues is described as 999 follows: 1001 1. The ITR will keep state of the effective MTU for each Locator per 1002 Map-Cache entry. The effective MTU is what the core network can 1003 deliver along the path between the ITR and ETR. 1005 2. When an IPv4-encapsulated packet with the DF bit set to 1, 1006 exceeds what the core network can deliver, one of the 1007 intermediate routers on the path will send an an ICMPv4 1008 Unreachable/Fragmentation-Needed to the ITR, respectively. The 1009 ITR will parse the ICMP message to determine which Locator is 1010 affected by the effective MTU change and then record the new 1011 effective MTU value in the Map-Cache entry. 1013 3. When a packet is received by the ITR from a source inside of the 1014 site and the size of the packet is greater than the effective MTU 1015 stored with the Map-Cache entry associated with the destination 1016 EID the packet is for, the ITR will send an ICMPv4 ICMP 1017 Unreachable/Fragmentation-Needed message back to the source. The 1018 packet size advertised by the ITR in the ICMP message is the 1019 effective MTU minus the LISP encapsulation length. 1021 Even though this mechanism is stateful, it has advantages over the 1022 stateless IP fragmentation mechanism, by not involving the 1023 destination host with reassembly of ITR fragmented packets. 1025 Please note that [RFC1191] and [RFC1981], which describe the use of 1026 ICMP packets for PMTU discovery, can behave suboptimally in the 1027 presence of ICMP black holes or off-path attackers that spoof ICMP. 1028 Possible mitigations include ITRs and ETRs cooperating on MTU probe 1029 packets ([RFC4821], [I-D.ietf-tsvwg-datagram-plpmtud]), or ITRs 1030 storing the beginning of large packets to verify that they match the 1031 echoed packet in ICMP Frag Needed/PTB. 1033 8. Using Virtualization and Segmentation with LISP 1035 There are several cases where segregation is needed at the EID level. 1036 For instance, this is the case for deployments containing overlapping 1037 addresses, traffic isolation policies or multi-tenant virtualization. 1038 For these and other scenarios where segregation is needed, Instance 1039 IDs are used. 1041 An Instance ID can be carried in a LISP-encapsulated packet. An ITR 1042 that prepends a LISP header will copy a 24-bit value used by the LISP 1043 router to uniquely identify the address space. The value is copied 1044 to the 'Instance ID' field of the LISP header, and the I-bit is set 1045 to 1. 1047 When an ETR decapsulates a packet, the Instance ID from the LISP 1048 header is used as a table identifier to locate the forwarding table 1049 to use for the inner destination EID lookup. 1051 For example, an 802.1Q VLAN tag or VPN identifier could be used as a 1052 24-bit Instance ID. See [I-D.ietf-lisp-vpn] for LISP VPN use-case 1053 details. Please note that the Instance ID is not protected, an on- 1054 path attacker can modify the tags and for instance, allow 1055 communicatons between logically isolated VLANs. 1057 Participants within a LISP deployment must agree on the meaning of 1058 Instance ID values. The source and destination EIDs MUST belong to 1059 the same Instance ID. 1061 Instance ID SHOULD NOT be used with overlapping IPv6 EID addresses. 1063 9. Routing Locator Selection 1065 The Map-Cache contains the state used by ITRs and PITRs to 1066 encapsulate packets. When an ITR/PITR receives a packet from inside 1067 the LISP site to a destination outside of the site a longest-prefix 1068 match lookup of the EID is done to the Map-Cache (see Section 6). 1069 The lookup returns a single Locator-Set containing a list of RLOCs 1070 corresponding to the EID's topological location. Each RLOC in the 1071 Locator-Set is associated with a 'Priority' and 'Weight', this 1072 information is used to select the RLOC to encapsulate. 1074 The RLOC with the lowest 'Priority' is selected. An RLOC with 1075 'Priority' 255 means that MUST NOT be used for forwarding. When 1076 multiple RLOCs have the same 'Priority' then the 'Weight' states how 1077 to load balance traffic among them. The value of the 'Weight' 1078 represents the relative weight of the total packets that match the 1079 mapping entry. 1081 The following are different scenarios for choosing RLOCs and the 1082 controls that are available: 1084 o The server-side returns one RLOC. The client-side can only use 1085 one RLOC. The server-side has complete control of the selection. 1087 o The server-side returns a list of RLOCs where a subset of the list 1088 has the same best Priority. The client can only use the subset 1089 list according to the weighting assigned by the server-side. In 1090 this case, the server-side controls both the subset list and load- 1091 splitting across its members. The client-side can use RLOCs 1092 outside of the subset list if it determines that the subset list 1093 is unreachable (unless RLOCs are set to a Priority of 255). Some 1094 sharing of control exists: the server-side determines the 1095 destination RLOC list and load distribution while the client-side 1096 has the option of using alternatives to this list if RLOCs in the 1097 list are unreachable. 1099 o The server-side sets a Weight of zero for the RLOC subset list. 1100 In this case, the client-side can choose how the traffic load is 1101 spread across the subset list. See Section 12 for details on 1102 load-sharing mechanisms. Control is shared by the server-side 1103 determining the list and the client-side determining load 1104 distribution. Again, the client can use alternative RLOCs if the 1105 server-provided list of RLOCs is unreachable. 1107 o Either side (more likely the server-side ETR) decides to "glean" 1108 the RLOCs. For example, if the server-side ETR gleans RLOCs, then 1109 the client-side ITR gives the client-side ITR responsibility for 1110 bidirectional RLOC reachability and preferability. Server-side 1111 ETR gleaning of the client-side ITR RLOC is done by caching the 1112 inner-header source EID and the outer-header source RLOC of 1113 received packets. The client-side ITR controls how traffic is 1114 returned and can alternate using an outer-header source RLOC, 1115 which then can be added to the list the server-side ETR uses to 1116 return traffic. Since no Priority or Weights are provided using 1117 this method, the server-side ETR MUST assume that each client-side 1118 ITR RLOC uses the same best Priority with a Weight of zero. In 1119 addition, since EID-Prefix encoding cannot be conveyed in data 1120 packets, the EID-to-RLOC Cache on Tunnel Routers can grow to be 1121 very large. Gleaning has several important considerations. A 1122 "gleaned" Map-Cache entry is only stored and used for a 1123 RECOMMENDED period of 3 seconds, pending verification. 1124 Verification MUST be performed by sending a Map-Request to the 1125 source EID (the inner-header IP source address) of the received 1126 encapsulated packet. A reply to this "verifying Map-Request" is 1127 used to fully populate the Map-Cache entry for the "gleaned" EID 1128 and is stored and used for the time indicated from the 'TTL' field 1129 of a received Map-Reply. When a verified Map- Cache entry is 1130 stored, data gleaning no longer occurs for subsequent packets that 1131 have a source EID that matches the EID-Prefix of the verified 1132 entry. This "gleaning" mechanism MUST NOT be used over the public 1133 Internet and SHOULD only be used in trusted and closed 1134 deployments. Refer to Section 16 for security issues regarding 1135 this mechanism. 1137 RLOCs that appear in EID-to-RLOC Map-Reply messages are assumed to be 1138 reachable when the R-bit [I-D.ietf-lisp-rfc6833bis] for the Locator 1139 record is set to 1. When the R-bit is set to 0, an ITR or PITR MUST 1140 NOT encapsulate to the RLOC. Neither the information contained in a 1141 Map-Reply nor that stored in the mapping database system provides 1142 reachability information for RLOCs. Note that reachability is not 1143 part of the mapping system and is determined using one or more of the 1144 Routing Locator reachability algorithms described in the next 1145 section. 1147 10. Routing Locator Reachability 1149 Several Data-Plane mechanisms for determining RLOC reachability are 1150 currently defined. Please note that additional Control-Plane based 1151 reachability mechanisms are defined in [I-D.ietf-lisp-rfc6833bis]. 1153 1. An ETR MAY examine the Locator-Status-Bits in the LISP header of 1154 an encapsulated data packet received from an ITR. If the ETR is 1155 also acting as an ITR and has traffic to return to the original 1156 ITR site, it can use this status information to help select an 1157 RLOC. 1159 2. When an ETR receives an encapsulated packet from an ITR, the 1160 source RLOC from the outer header of the packet is likely to be 1161 reachable. Please note that in some scenarios the RLOC from the 1162 outer header can be an spoofable field. 1164 3. An ITR/ETR pair can use the 'Echo-Noncing' Locator reachability 1165 algorithms described in this section. 1167 When determining Locator up/down reachability by examining the 1168 Locator-Status-Bits from the LISP-encapsulated data packet, an ETR 1169 will receive up-to-date status from an encapsulating ITR about 1170 reachability for all ETRs at the site. CE-based ITRs at the source 1171 site can determine reachability relative to each other using the site 1172 IGP as follows: 1174 o Under normal circumstances, each ITR will advertise a default 1175 route into the site IGP. 1177 o If an ITR fails or if the upstream link to its PE fails, its 1178 default route will either time out or be withdrawn. 1180 Each ITR can thus observe the presence or lack of a default route 1181 originated by the others to determine the Locator-Status-Bits it sets 1182 for them. 1184 When ITRs at the site are not deployed in CE routers, the IGP can 1185 still be used to determine the reachability of Locators, provided 1186 they are injected into the IGP. This is typically done when a /32 1187 address is configured on a loopback interface. 1189 RLOCs listed in a Map-Reply are numbered with ordinals 0 to n-1. The 1190 Locator-Status-Bits in a LISP-encapsulated packet are numbered from 0 1191 to n-1 starting with the least significant bit. For example, if an 1192 RLOC listed in the 3rd position of the Map-Reply goes down (ordinal 1193 value 2), then all ITRs at the site will clear the 3rd least 1194 significant bit (xxxx x0xx) of the 'Locator-Status-Bits' field for 1195 the packets they encapsulate. 1197 When an xTR decides to use 'Locator-Status-Bits' to affect 1198 reachability information, it acts as follows: ETRs decapsulating a 1199 packet will check for any change in the 'Locator-Status-Bits' field. 1200 When a bit goes from 1 to 0, the ETR, if acting also as an ITR, will 1201 refrain from encapsulating packets to an RLOC that is indicated as 1202 down. It will only resume using that RLOC if the corresponding 1203 Locator-Status-Bit returns to a value of 1. Locator-Status-Bits are 1204 associated with a Locator-Set per EID-Prefix. Therefore, when a 1205 Locator becomes unreachable, the Locator-Status-Bit that corresponds 1206 to that Locator's position in the list returned by the last Map-Reply 1207 will be set to zero for that particular EID-Prefix. 1209 Locator-Status-Bits MUST NOT be used over the public Internet and 1210 SHOULD only be used in trusted and closed deployments. In addition 1211 Locator-Status-Bits SHOULD be coupled with Map-Versioning 1212 [I-D.ietf-lisp-6834bis] to prevent race conditions where Locator- 1213 Status-Bits are interpreted as referring to different RLOCs than 1214 intended. Refer to Section 16 for security issues regarding this 1215 mechanism. 1217 If an ITR encapsulates a packet to an ETR and the packet is received 1218 and decapsulated by the ETR, it is implied but not confirmed by the 1219 ITR that the ETR's RLOC is reachable. In most cases, the ETR can 1220 also reach the ITR but cannot assume this to be true, due to the 1221 possibility of path asymmetry. In the presence of unidirectional 1222 traffic flow from an ITR to an ETR, the ITR SHOULD NOT use the lack 1223 of return traffic as an indication that the ETR is unreachable. 1225 Instead, it MUST use an alternate mechanism to determine 1226 reachability. 1228 The security considerations of Section 16 related to data-plane 1229 reachability applies to the data-plane RLOC reachability mechanisms 1230 described in this section. 1232 10.1. Echo Nonce Algorithm 1234 When data flows bidirectionally between Locators from different 1235 sites, a Data-Plane mechanism called "nonce echoing" can be used to 1236 determine reachability between an ITR and ETR. When an ITR wants to 1237 solicit a nonce echo, it sets the N- and E-bits and places a 24-bit 1238 nonce [RFC4086] in the LISP header of the next encapsulated data 1239 packet. 1241 When this packet is received by the ETR, the encapsulated packet is 1242 forwarded as normal. When the ETR is an xTR (co-located as an ITR), 1243 it then sends a data packet to the ITR (when it is an xTR co-located 1244 as an ETR), it includes the nonce received earlier with the N-bit set 1245 and E-bit cleared. The ITR sees this "echoed nonce" and knows that 1246 the path to and from the ETR is up. 1248 The ITR will set the E-bit and N-bit for every packet it sends while 1249 in the echo-nonce-request state. The time the ITR waits to process 1250 the echoed nonce before it determines the path is unreachable is 1251 variable and is a choice left for the implementation. 1253 If the ITR is receiving packets from the ETR but does not see the 1254 nonce echoed while being in the echo-nonce-request state, then the 1255 path to the ETR is unreachable. This decision MAY be overridden by 1256 other Locator reachability algorithms. Once the ITR determines that 1257 the path to the ETR is down, it can switch to another Locator for 1258 that EID-Prefix. 1260 Note that "ITR" and "ETR" are relative terms here. Both devices MUST 1261 be implementing both ITR and ETR functionality for the echo nonce 1262 mechanism to operate. 1264 The ITR and ETR MAY both go into the echo-nonce-request state at the 1265 same time. The number of packets sent or the time during which echo 1266 nonce requests are sent is an implementation-specific setting. In 1267 this case, an xTR receiving the echo-nonce-request packets will 1268 suspend the echo-nonce-request state and setup a 'echo-nonce-request- 1269 state' timer. After the 'echo-nonce-request-state' timer expires it 1270 will resume the echo-nonce-request state. 1272 This mechanism does not completely solve the forward path 1273 reachability problem, as traffic may be unidirectional. That is, the 1274 ETR receiving traffic at a site MAY not be the same device as an ITR 1275 that transmits traffic from that site, or the site-to-site traffic is 1276 unidirectional so there is no ITR returning traffic. 1278 The echo-nonce algorithm is bilateral. That is, if one side sets the 1279 E-bit and the other side is not enabled for echo-noncing, then the 1280 echoing of the nonce does not occur and the requesting side may 1281 erroneously consider the Locator unreachable. An ITR SHOULD set the 1282 E-bit in an encapsulated data packet when it knows the ETR is enabled 1283 for echo-noncing. This is conveyed by the E-bit in the Map-Reply 1284 message. 1286 Many implementations default to not advertising they are echo-nonce 1287 capable in Map-Reply messages and so RLOC-probing tends to be used 1288 for RLOC reachability. 1290 The echo-nonce mechanism MUST NOT be used over the public Internet 1291 and MUST only be used in trusted and closed deployments. Refer to 1292 Section 16 for security issues regarding this mechanism. 1294 11. EID Reachability within a LISP Site 1296 A site MAY be multihomed using two or more ETRs. The hosts and 1297 infrastructure within a site will be addressed using one or more EID- 1298 Prefixes that are mapped to the RLOCs of the relevant ETRs in the 1299 mapping system. One possible failure mode is for an ETR to lose 1300 reachability to one or more of the EID-Prefixes within its own site. 1301 When this occurs when the ETR sends Map-Replies, it can clear the 1302 R-bit associated with its own Locator. And when the ETR is also an 1303 ITR, it can clear its Locator-Status-Bit in the encapsulation data 1304 header. 1306 It is recognized that there are no simple solutions to the site 1307 partitioning problem because it is hard to know which part of the 1308 EID-Prefix range is partitioned and which Locators can reach any sub- 1309 ranges of the EID-Prefixes. Note that this is not a new problem 1310 introduced by the LISP architecture. The problem exists today when a 1311 multihomed site uses BGP to advertise its reachability upstream. 1313 12. Routing Locator Hashing 1315 When an ETR provides an EID-to-RLOC mapping in a Map-Reply message 1316 that is stored in the Map-Cache of a requesting ITR, the Locator-Set 1317 for the EID-Prefix MAY contain different Priority and Weight values 1318 for each locator address. When more than one best Priority Locator 1319 exists, the ITR can decide how to load-share traffic against the 1320 corresponding Locators. 1322 The following hash algorithm MAY be used by an ITR to select a 1323 Locator for a packet destined to an EID for the EID-to-RLOC mapping: 1325 1. Either a source and destination address hash or the traditional 1326 5-tuple hash can be used. The traditional 5-tuple hash includes 1327 the source and destination addresses; source and destination TCP, 1328 UDP, or Stream Control Transmission Protocol (SCTP) port numbers; 1329 and the IP protocol number field or IPv6 next-protocol fields of 1330 a packet that a host originates from within a LISP site. When a 1331 packet is not a TCP, UDP, or SCTP packet, the source and 1332 destination addresses only from the header are used to compute 1333 the hash. 1335 2. Take the hash value and divide it by the number of Locators 1336 stored in the Locator-Set for the EID-to-RLOC mapping. 1338 3. The remainder will yield a value of 0 to "number of Locators 1339 minus 1". Use the remainder to select the Locator in the 1340 Locator-Set. 1342 The specific hash algorithm the ITR uses for load-sharing is out of 1343 scope for this document and does not prevent interoperability. 1345 The Source port SHOULD be the same for all packets belonging to the 1346 same flow. Also note that when a packet is LISP encapsulated, the 1347 source port number in the outer UDP header needs to be set. 1348 Selecting a hashed value allows core routers that are attached to 1349 Link Aggregation Groups (LAGs) to load-split the encapsulated packets 1350 across member links of such LAGs. Otherwise, core routers would see 1351 a single flow, since packets have a source address of the ITR, for 1352 packets that are originated by different EIDs at the source site. A 1353 suggested setting for the source port number computed by an ITR is a 1354 5-tuple hash function on the inner header, as described above. The 1355 source port SHOULD be the same for all packets belonging to the same 1356 flow. 1358 Many core router implementations use a 5-tuple hash to decide how to 1359 balance packet load across members of a LAG. The 5-tuple hash 1360 includes the source and destination addresses of the packet and the 1361 source and destination ports when the protocol number in the packet 1362 is TCP or UDP. For this reason, UDP encoding is used for LISP 1363 encapsulation. In this scenario, when the outer header is IPv6, the 1364 flow label MAY also be set following the procedures specified in 1365 [RFC6438]. When the inner header is IPv6 then the flow label is not 1366 zero, it MAY be used to compute the hash. 1368 13. Changing the Contents of EID-to-RLOC Mappings 1370 Since the LISP architecture uses a caching scheme to retrieve and 1371 store EID-to-RLOC mappings, the only way an ITR can get a more up-to- 1372 date mapping is to re-request the mapping. However, the ITRs do not 1373 know when the mappings change, and the ETRs do not keep track of 1374 which ITRs requested its mappings. For scalability reasons, it is 1375 desirable to maintain this approach but need to provide a way for 1376 ETRs to change their mappings and inform the sites that are currently 1377 communicating with the ETR site using such mappings. 1379 This section defines two Data-Plane mechanism for updating EID-to- 1380 RLOC mappings. Additionally, the Solicit-Map Request (SMR) Control- 1381 Plane updating mechanism is specified in [I-D.ietf-lisp-rfc6833bis]. 1383 13.1. Locator-Status-Bits 1385 Locator-Status-Bits (LSB) can also be used to keep track of the 1386 Locator status (up or down) when EID-to-RLOC mappings are changing. 1387 When LSB are used in a LISP deployment, all LISP tunnel routers MUST 1388 implement both ITR and ETR capabilities (therefore all tunnel routers 1389 are effectively xTRs). In this section the term "source xTR" is used 1390 to refer to the xTR setting the LSB and "destination xTR" is used to 1391 refer to the xTR receiving the LSB. The procedure is as follows: 1393 First, when a Locator record is added or removed from the Locator- 1394 Set, the source xTR will signal this by sending a Solicit-Map Request 1395 (SMR) Control-Plane message [I-D.ietf-lisp-rfc6833bis] to the 1396 destination xTR. At this point the source xTR MUST NOT use LSB 1397 (L-bit = 0) since the destination xTR site has outdated information. 1398 The source xTR will setup a 'use-LSB' timer. 1400 Second and as defined in [I-D.ietf-lisp-rfc6833bis], upon reception 1401 of the SMR message the destination xTR will retrieve the updated EID- 1402 to-RLOC mappings by sending a Map-Request. 1404 And third, when the 'use-LSB' timer expires, the source xTR can use 1405 again LSB with the destination xTR to signal the Locator status (up 1406 or down). The specific value for the 'use-LSB' timer depends on the 1407 LISP deployment, the 'use-LSB' timer needs to be large enough for the 1408 destination xTR to retreive the updated EID-to-RLOC mappings. A 1409 RECOMMENDED value for the 'use-LSB' timer is 5 minutes. 1411 13.2. Database Map-Versioning 1413 When there is unidirectional packet flow between an ITR and ETR, and 1414 the EID-to-RLOC mappings change on the ETR, it needs to inform the 1415 ITR so encapsulation to a removed Locator can stop and can instead be 1416 started to a new Locator in the Locator-Set. 1418 An ETR, when it sends Map-Reply messages, conveys its own Map-Version 1419 Number. This is known as the Destination Map-Version Number. ITRs 1420 include the Destination Map-Version Number in packets they 1421 encapsulate to the site. When an ETR decapsulates a packet and 1422 detects that the Destination Map-Version Number is less than the 1423 current version for its mapping, the SMR procedure described in 1424 [I-D.ietf-lisp-rfc6833bis] occurs. 1426 An ITR, when it encapsulates packets to ETRs, can convey its own Map- 1427 Version Number. This is known as the Source Map-Version Number. 1428 When an ETR decapsulates a packet and detects that the Source Map- 1429 Version Number is greater than the last Map-Version Number sent in a 1430 Map-Reply from the ITR's site, the ETR will send a Map-Request to one 1431 of the ETRs for the source site. 1433 A Map-Version Number is used as a sequence number per EID-Prefix, so 1434 values that are greater are considered to be more recent. A value of 1435 0 for the Source Map-Version Number or the Destination Map-Version 1436 Number conveys no versioning information, and an ITR does no 1437 comparison with previously received Map-Version Numbers. 1439 A Map-Version Number can be included in Map-Register messages as 1440 well. This is a good way for the Map-Server to assure that all ETRs 1441 for a site registering to it will be synchronized according to Map- 1442 Version Number. 1444 Map-Version requires that ETRs within the LISP site are synchronized 1445 with respect to the Map-Version Number, EID-prefix and the set and 1446 status (up/down) of the RLOCs. The use of Map-Versioning without 1447 proper synchronization may cause traffic disruption. The 1448 synchronization protocol is out-of-the-scope of this document, but 1449 MUST keep ETRs synchronized within a 1 minute window. 1451 Map-Versioning MUST NOT be used over the public Internet and SHOULD 1452 only be used in trusted and closed deployments. Refer to Section 16 1453 for security issues regarding this mechanism. 1455 See [I-D.ietf-lisp-6834bis] for a more detailed analysis and 1456 description of Database Map-Versioning. 1458 14. Multicast Considerations 1460 A multicast group address, as defined in the original Internet 1461 architecture, is an identifier of a grouping of topologically 1462 independent receiver host locations. The address encoding itself 1463 does not determine the location of the receiver(s). The multicast 1464 routing protocol, and the network-based state the protocol creates, 1465 determine where the receivers are located. 1467 In the context of LISP, a multicast group address is both an EID and 1468 a Routing Locator. Therefore, no specific semantic or action needs 1469 to be taken for a destination address, as it would appear in an IP 1470 header. Therefore, a group address that appears in an inner IP 1471 header built by a source host will be used as the destination EID. 1472 The outer IP header (the destination Routing Locator address), 1473 prepended by a LISP router, can use the same group address as the 1474 destination Routing Locator, use a multicast or unicast Routing 1475 Locator obtained from a Mapping System lookup, or use other means to 1476 determine the group address mapping. 1478 With respect to the source Routing Locator address, the ITR prepends 1479 its own IP address as the source address of the outer IP header, just 1480 like it would if the destination EID was a unicast address. This 1481 source Routing Locator address, like any other Routing Locator 1482 address, MUST be routable on the underlay. 1484 There are two approaches for LISP-Multicast, one that uses native 1485 multicast routing in the underlay with no support from the Mapping 1486 System and the other that uses only unicast routing in the underlay 1487 with support from the Mapping System. See [RFC6831] and [RFC8378], 1488 respectively, for details. Details for LISP-Multicast and 1489 interworking with non-LISP sites are described in [RFC6831] and 1490 [RFC6832]. 1492 15. Router Performance Considerations 1494 LISP is designed to be very "hardware-based forwarding friendly". A 1495 few implementation techniques can be used to incrementally implement 1496 LISP: 1498 o When a tunnel-encapsulated packet is received by an ETR, the outer 1499 destination address may not be the address of the router. This 1500 makes it challenging for the control plane to get packets from the 1501 hardware. This may be mitigated by creating special Forwarding 1502 Information Base (FIB) entries for the EID-Prefixes of EIDs served 1503 by the ETR (those for which the router provides an RLOC 1504 translation). These FIB entries are marked with a flag indicating 1505 that Control-Plane processing SHOULD be performed. The forwarding 1506 logic of testing for particular IP protocol number values is not 1507 necessary. There are a few proven cases where no changes to 1508 existing deployed hardware were needed to support the LISP Data- 1509 Plane. 1511 o On an ITR, prepending a new IP header consists of adding more 1512 octets to a MAC rewrite string and prepending the string as part 1513 of the outgoing encapsulation procedure. Routers that support 1514 Generic Routing Encapsulation (GRE) tunneling [RFC2784] or 6to4 1515 tunneling [RFC3056] may already support this action. 1517 o A packet's source address or interface the packet was received on 1518 can be used to select VRF (Virtual Routing/Forwarding). The VRF's 1519 routing table can be used to find EID-to-RLOC mappings. 1521 For performance issues related to Map-Cache management, see 1522 Section 16. 1524 16. Security Considerations 1526 In what follows we highlight security considerations that apply when 1527 LISP is deployed in environments such as those specified in 1528 Section 1.1. 1530 The optional mechanisms of gleaning is offered to directly obtain a 1531 mapping from the LISP encapsulated packets. Specifically, an xTR can 1532 learn the EID-to-RLOC mapping by inspecting the source RLOC and 1533 source EID of an encapsulated packet, and insert this new mapping 1534 into its Map-Cache. An off-path attacker can spoof the source EID 1535 address to divert the traffic sent to the victim's spoofed EID. If 1536 the attacker spoofs the source RLOC, it can mount a DoS attack by 1537 redirecting traffic to the spoofed victim's RLOC, potentially 1538 overloading it. 1540 The LISP Data-Plane defines several mechanisms to monitor RLOC Data- 1541 Plane reachability, in this context Locator-Status Bits, Nonce- 1542 Present and Echo-Nonce bits of the LISP encapsulation header can be 1543 manipulated by an attacker to mount a DoS attack. An off-path 1544 attacker able to spoof the RLOC and/or nonce of a victim's xTR can 1545 manipulate such mechanisms to declare false information about the 1546 RLOC's reachability status. 1548 For example of such attacks, an off-path attacker can exploit the 1549 echo-nonce mechanism by sending data packets to an ITR with a random 1550 nonce from an ETR's spoofed RLOC. Note the attacker must guess a 1551 valid nonce the ITR is requesting to be echoed within a small window 1552 of time. The goal is to convince the ITR that the ETR's RLOC is 1553 reachable even when it may not be reachable. If the attack is 1554 successful, the ITR believes the wrong reachability status of the 1555 ETR's RLOC until RLOC-probing detects the correct status. This time 1556 frame is on the order of 10s of seconds. This specific attack can be 1557 mitigated by preventing RLOC spoofing in the network by deploying 1558 uRPF BCP 38 [RFC2827]. In addition and in order to exploit this 1559 vulnerability, the off-path attacker must send echo-nonce packets at 1560 high rate. If the nonces have never been requested by the ITR, it 1561 can protect itself from erroneous reachability attacks. 1563 A LISP-specific uRPF check is also possible. When decapsulating, an 1564 ETR can check that the source EID and RLOC are valid EID-to-RLOC 1565 mappings by checking the Mapping System. 1567 Map-Versioning is a Data-Plane mechanism used to signal a peering xTR 1568 that a local EID-to-RLOC mapping has been updated, so that the 1569 peering xTR uses LISP Control-Plane signaling message to retrieve a 1570 fresh mapping. This can be used by an attacker to forge the map- 1571 versioning field of a LISP encapsulated header and force an excessive 1572 amount of signaling between xTRs that may overload them. Further 1573 security considerations on Map-Versioning can be found in 1574 [I-D.ietf-lisp-6834bis]. 1576 Locator-Status-Bits, echo-nonce and map-versioning MUST NOT be used 1577 over the public Internet and SHOULD only be used in trusted and 1578 closed deployments. In addition Locator-Status-Bits SHOULD be 1579 coupled with map-versioning to prevent race conditions where Locator- 1580 Status-Bits are interpreted as referring to different RLOCs than 1581 intended. 1583 LISP implementations and deployments which permit outer header 1584 fragments of IPv6 LISP encapsulated packets as a means of dealing 1585 with MTU issues should also use implementation techniques in ETRs to 1586 prevent this from being a DoS attack vector. Limits on the number of 1587 fragments awaiting reassembly at an ETR, RTR, or PETR, and the rate 1588 of admitting such fragments may be used. 1590 17. Network Management Considerations 1592 Considerations for network management tools exist so the LISP 1593 protocol suite can be operationally managed. These mechanisms can be 1594 found in [RFC7052] and [RFC6835]. 1596 18. Changes since RFC 6830 1598 For implementation considerations, the following changes have been 1599 made to this document since RFC 6830 was published: 1601 o It is no longer mandated that a maximum number of 2 LISP headers 1602 be prepended to a packet. If there is a application need for more 1603 than 2 LISP headers, an implementation can support more. However, 1604 it is RECOMMENDED that a maximum of two LISP headers can be 1605 prepended to a packet. 1607 o The 3 reserved flag bits in the LISP header have been allocated 1608 for [RFC8061]. The low-order 2 bits of the 3-bit field (now named 1609 the KK bits) are used as a key identifier. The 1 remaining bit is 1610 still documented as reserved and unassigned. 1612 o Data-Plane gleaning for creating map-cache entries has been made 1613 optional. Any ITR implementations that depend on or assume the 1614 remote ETR is gleaning should not do so. This does not create any 1615 interoperability problems since the control-plane map-cache 1616 population procedures are unilateral and are the typical method 1617 for map-cache population. 1619 o The bulk of the changes to this document which reduces its length 1620 are due to moving the LISP control-plane messaging and procedures 1621 to [I-D.ietf-lisp-rfc6833bis]. 1623 19. IANA Considerations 1625 This section provides guidance to the Internet Assigned Numbers 1626 Authority (IANA) regarding registration of values related to this 1627 Data-Plane LISP specification, in accordance with BCP 26 [RFC8126]. 1629 19.1. LISP UDP Port Numbers 1631 The IANA registry has allocated UDP port number 4341 for the LISP 1632 Data-Plane. IANA has updated the description for UDP port 4341 as 1633 follows: 1635 lisp-data 4341 udp LISP Data Packets 1637 20. References 1639 20.1. Normative References 1641 [I-D.ietf-lisp-6834bis] 1642 Iannone, L., Saucez, D., and O. Bonaventure, "Locator/ID 1643 Separation Protocol (LISP) Map-Versioning", draft-ietf- 1644 lisp-6834bis-09 (work in progress), August 2021. 1646 [I-D.ietf-lisp-rfc6833bis] 1647 Farinacci, D., Maino, F., Fuller, V., and A. Cabellos, 1648 "Locator/ID Separation Protocol (LISP) Control-Plane", 1649 draft-ietf-lisp-rfc6833bis-30 (work in progress), November 1650 2020. 1652 [RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768, 1653 DOI 10.17487/RFC0768, August 1980, 1654 . 1656 [RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, 1657 DOI 10.17487/RFC0791, September 1981, 1658 . 1660 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1661 Requirement Levels", BCP 14, RFC 2119, 1662 DOI 10.17487/RFC2119, March 1997, 1663 . 1665 [RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, 1666 "Definition of the Differentiated Services Field (DS 1667 Field) in the IPv4 and IPv6 Headers", RFC 2474, 1668 DOI 10.17487/RFC2474, December 1998, 1669 . 1671 [RFC2827] Ferguson, P. and D. Senie, "Network Ingress Filtering: 1672 Defeating Denial of Service Attacks which employ IP Source 1673 Address Spoofing", BCP 38, RFC 2827, DOI 10.17487/RFC2827, 1674 May 2000, . 1676 [RFC2983] Black, D., "Differentiated Services and Tunnels", 1677 RFC 2983, DOI 10.17487/RFC2983, October 2000, 1678 . 1680 [RFC6040] Briscoe, B., "Tunnelling of Explicit Congestion 1681 Notification", RFC 6040, DOI 10.17487/RFC6040, November 1682 2010, . 1684 [RFC6438] Carpenter, B. and S. Amante, "Using the IPv6 Flow Label 1685 for Equal Cost Multipath Routing and Link Aggregation in 1686 Tunnels", RFC 6438, DOI 10.17487/RFC6438, November 2011, 1687 . 1689 [RFC6830] Farinacci, D., Fuller, V., Meyer, D., and D. Lewis, "The 1690 Locator/ID Separation Protocol (LISP)", RFC 6830, 1691 DOI 10.17487/RFC6830, January 2013, 1692 . 1694 [RFC6831] Farinacci, D., Meyer, D., Zwiebel, J., and S. Venaas, "The 1695 Locator/ID Separation Protocol (LISP) for Multicast 1696 Environments", RFC 6831, DOI 10.17487/RFC6831, January 1697 2013, . 1699 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 1700 Writing an IANA Considerations Section in RFCs", BCP 26, 1701 RFC 8126, DOI 10.17487/RFC8126, June 2017, 1702 . 1704 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1705 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1706 May 2017, . 1708 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 1709 (IPv6) Specification", STD 86, RFC 8200, 1710 DOI 10.17487/RFC8200, July 2017, 1711 . 1713 [RFC8378] Moreno, V. and D. Farinacci, "Signal-Free Locator/ID 1714 Separation Protocol (LISP) Multicast", RFC 8378, 1715 DOI 10.17487/RFC8378, May 2018, 1716 . 1718 20.2. Informative References 1720 [AFN] IANA, "Address Family Numbers", August 2016, 1721 . 1723 [CHIAPPA] Chiappa, J., "Endpoints and Endpoint names: A Proposed", 1724 1999, 1725 . 1727 [I-D.ietf-lisp-introduction] 1728 Cabellos, A. and D. S. (Ed.), "An Architectural 1729 Introduction to the Locator/ID Separation Protocol 1730 (LISP)", draft-ietf-lisp-introduction-15 (work in 1731 progress), September 2021. 1733 [I-D.ietf-lisp-vpn] 1734 Moreno, V. and D. Farinacci, "LISP Virtual Private 1735 Networks (VPNs)", draft-ietf-lisp-vpn-08 (work in 1736 progress), January 2022. 1738 [I-D.ietf-tsvwg-datagram-plpmtud] 1739 Fairhurst, G., Jones, T., Tuexen, M., Ruengeler, I., and 1740 T. Voelker, "Packetization Layer Path MTU Discovery for 1741 Datagram Transports", draft-ietf-tsvwg-datagram-plpmtud-22 1742 (work in progress), June 2020. 1744 [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", 1745 STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987, 1746 . 1748 [RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191, 1749 DOI 10.17487/RFC1191, November 1990, 1750 . 1752 [RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G., 1753 and E. Lear, "Address Allocation for Private Internets", 1754 BCP 5, RFC 1918, DOI 10.17487/RFC1918, February 1996, 1755 . 1757 [RFC1981] McCann, J., Deering, S., and J. Mogul, "Path MTU Discovery 1758 for IP version 6", RFC 1981, DOI 10.17487/RFC1981, August 1759 1996, . 1761 [RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P. 1762 Traina, "Generic Routing Encapsulation (GRE)", RFC 2784, 1763 DOI 10.17487/RFC2784, March 2000, 1764 . 1766 [RFC3056] Carpenter, B. and K. Moore, "Connection of IPv6 Domains 1767 via IPv4 Clouds", RFC 3056, DOI 10.17487/RFC3056, February 1768 2001, . 1770 [RFC3232] Reynolds, J., Ed., "Assigned Numbers: RFC 1700 is Replaced 1771 by an On-line Database", RFC 3232, DOI 10.17487/RFC3232, 1772 January 2002, . 1774 [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, 1775 A., Peterson, J., Sparks, R., Handley, M., and E. 1776 Schooler, "SIP: Session Initiation Protocol", RFC 3261, 1777 DOI 10.17487/RFC3261, June 2002, 1778 . 1780 [RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker, 1781 "Randomness Requirements for Security", BCP 106, RFC 4086, 1782 DOI 10.17487/RFC4086, June 2005, 1783 . 1785 [RFC4459] Savola, P., "MTU and Fragmentation Issues with In-the- 1786 Network Tunneling", RFC 4459, DOI 10.17487/RFC4459, April 1787 2006, . 1789 [RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU 1790 Discovery", RFC 4821, DOI 10.17487/RFC4821, March 2007, 1791 . 1793 [RFC4984] Meyer, D., Ed., Zhang, L., Ed., and K. Fall, Ed., "Report 1794 from the IAB Workshop on Routing and Addressing", 1795 RFC 4984, DOI 10.17487/RFC4984, September 2007, 1796 . 1798 [RFC6832] Lewis, D., Meyer, D., Farinacci, D., and V. Fuller, 1799 "Interworking between Locator/ID Separation Protocol 1800 (LISP) and Non-LISP Sites", RFC 6832, 1801 DOI 10.17487/RFC6832, January 2013, 1802 . 1804 [RFC6835] Farinacci, D. and D. Meyer, "The Locator/ID Separation 1805 Protocol Internet Groper (LIG)", RFC 6835, 1806 DOI 10.17487/RFC6835, January 2013, 1807 . 1809 [RFC6935] Eubanks, M., Chimento, P., and M. Westerlund, "IPv6 and 1810 UDP Checksums for Tunneled Packets", RFC 6935, 1811 DOI 10.17487/RFC6935, April 2013, 1812 . 1814 [RFC6936] Fairhurst, G. and M. Westerlund, "Applicability Statement 1815 for the Use of IPv6 UDP Datagrams with Zero Checksums", 1816 RFC 6936, DOI 10.17487/RFC6936, April 2013, 1817 . 1819 [RFC7052] Schudel, G., Jain, A., and V. Moreno, "Locator/ID 1820 Separation Protocol (LISP) MIB", RFC 7052, 1821 DOI 10.17487/RFC7052, October 2013, 1822 . 1824 [RFC7215] Jakab, L., Cabellos-Aparicio, A., Coras, F., Domingo- 1825 Pascual, J., and D. Lewis, "Locator/Identifier Separation 1826 Protocol (LISP) Network Element Deployment 1827 Considerations", RFC 7215, DOI 10.17487/RFC7215, April 1828 2014, . 1830 [RFC8060] Farinacci, D., Meyer, D., and J. Snijders, "LISP Canonical 1831 Address Format (LCAF)", RFC 8060, DOI 10.17487/RFC8060, 1832 February 2017, . 1834 [RFC8061] Farinacci, D. and B. Weis, "Locator/ID Separation Protocol 1835 (LISP) Data-Plane Confidentiality", RFC 8061, 1836 DOI 10.17487/RFC8061, February 2017, 1837 . 1839 [RFC8085] Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage 1840 Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085, 1841 March 2017, . 1843 Appendix A. Acknowledgments 1845 An initial thank you goes to Dave Oran for planting the seeds for the 1846 initial ideas for LISP. His consultation continues to provide value 1847 to the LISP authors. 1849 A special and appreciative thank you goes to Noel Chiappa for 1850 providing architectural impetus over the past decades on separation 1851 of location and identity, as well as detailed reviews of the LISP 1852 architecture and documents, coupled with enthusiasm for making LISP a 1853 practical and incremental transition for the Internet. 1855 The original authors would like to gratefully acknowledge many people 1856 who have contributed discussions and ideas to the making of this 1857 proposal. They include Scott Brim, Andrew Partan, John Zwiebel, 1858 Jason Schiller, Lixia Zhang, Dorian Kim, Peter Schoenmaker, Vijay 1859 Gill, Geoff Huston, David Conrad, Mark Handley, Ron Bonica, Ted 1860 Seely, Mark Townsley, Chris Morrow, Brian Weis, Dave McGrew, Peter 1861 Lothberg, Dave Thaler, Eliot Lear, Shane Amante, Ved Kafle, Olivier 1862 Bonaventure, Luigi Iannone, Robin Whittle, Brian Carpenter, Joel 1863 Halpern, Terry Manderson, Roger Jorgensen, Ran Atkinson, Stig Venaas, 1864 Iljitsch van Beijnum, Roland Bless, Dana Blair, Bill Lynch, Marc 1865 Woolward, Damien Saucez, Damian Lezama, Attilla De Groot, Parantap 1866 Lahiri, David Black, Roque Gagliano, Isidor Kouvelas, Jesper Skriver, 1867 Fred Templin, Margaret Wasserman, Sam Hartman, Michael Hofling, Pedro 1868 Marques, Jari Arkko, Gregg Schudel, Srinivas Subramanian, Amit Jain, 1869 Xu Xiaohu, Dhirendra Trivedi, Yakov Rekhter, John Scudder, John 1870 Drake, Dimitri Papadimitriou, Ross Callon, Selina Heimlich, Job 1871 Snijders, Vina Ermagan, Fabio Maino, Victor Moreno, Chris White, 1872 Clarence Filsfils, Alia Atlas, Florin Coras and Alberto Rodriguez. 1874 This work originated in the Routing Research Group (RRG) of the IRTF. 1875 An individual submission was converted into the IETF LISP working 1876 group document that became this RFC. 1878 The LISP working group would like to give a special thanks to Jari 1879 Arkko, the Internet Area AD at the time that the set of LISP 1880 documents were being prepared for IESG last call, and for his 1881 meticulous reviews and detailed commentaries on the 7 working group 1882 last call documents progressing toward standards-track RFCs. 1884 The current authors would like to give a sincere thank you to the 1885 people who help put LISP on standards track in the IETF. They 1886 include Joel Halpern, Luigi Iannone, Deborah Brungard, Fabio Maino, 1887 Scott Bradner, Kyle Rose, Takeshi Takahashi, Sarah Banks, Pete 1888 Resnick, Colin Perkins, Mirja Kuhlewind, Francis Dupont, Benjamin 1889 Kaduk, Eric Rescorla, Alvaro Retana, Alexey Melnikov, Alissa Cooper, 1890 Suresh Krishnan, Alberto Rodriguez-Natal, Vina Ermagen, Mohamed 1891 Boucadair, Brian Trammell, Sabrina Tanamal, and John Drake. The 1892 contributions they offered greatly added to the security, scale, and 1893 robustness of the LISP architecture and protocols. 1895 Appendix B. Document Change Log 1897 [RFC Editor: Please delete this section on publication as RFC.] 1899 B.1. Changes to draft-ietf-lisp-rfc6830bis-37 1901 o Posted May 2022. 1903 o Added references to 6834bis instead of pointing text to 1904 Section 13.2. This is so we can advance the Map-Versioning draft 1905 rfc6834bis to proposed standard. 1907 B.2. Changes to draft-ietf-lisp-rfc6830bis-28 1909 o Posted November 2019. 1911 o Fixed how LSB behave in the presence of new/removed locators. 1913 o Added ETR synchronization requirements when using Map-Versioning. 1915 o Fixed a large set of minor comments and edits. 1917 B.3. Changes to draft-ietf-lisp-rfc6830bis-27 1919 o Posted April 2019 post telechat. 1921 o Made editorial corrections per Warren's suggestions. 1923 o Put in suggested text from Luigi that Mirja agreed with. 1925 o LSB, Echo-Nonce and Map-Versioning SHOULD be only used in closed 1926 environments. 1928 o Removed paragraph stating that Instance-ID can be 32-bit in the 1929 control-plane. 1931 o 6831/8378 are now normative. 1933 o Rewritten Security Considerations according to the changes. 1935 o Stated that LSB SHOULD be coupled with Map-Versioning. 1937 B.4. Changes to draft-ietf-lisp-rfc6830bis-26 1939 o Posted late October 2018. 1941 o Changed description about "reserved" bits to state "reserved and 1942 unassigned". 1944 B.5. Changes to draft-ietf-lisp-rfc6830bis-25 1946 o Posted mid October 2018. 1948 o Added more to the Security Considerations section with discussion 1949 about echo-nonce attacks. 1951 B.6. Changes to draft-ietf-lisp-rfc6830bis-24 1953 o Posted mid October 2018. 1955 o Final editorial changes for Eric and Ben. 1957 B.7. Changes to draft-ietf-lisp-rfc6830bis-23 1959 o Posted early October 2018. 1961 o Added an applicability statement in section 1 to address security 1962 concerns from Telechat. 1964 B.8. Changes to draft-ietf-lisp-rfc6830bis-22 1966 o Posted early October 2018. 1968 o Changes to reflect comments post Telechat. 1970 B.9. Changes to draft-ietf-lisp-rfc6830bis-21 1972 o Posted late-September 2018. 1974 o Changes to reflect comments from Sep 27th Telechat. 1976 B.10. Changes to draft-ietf-lisp-rfc6830bis-20 1978 o Posted late-September 2018. 1980 o Fix old reference to RFC3168, changed to RFC6040. 1982 B.11. Changes to draft-ietf-lisp-rfc6830bis-19 1984 o Posted late-September 2018. 1986 o More editorial changes. 1988 B.12. Changes to draft-ietf-lisp-rfc6830bis-18 1990 o Posted mid-September 2018. 1992 o Changes to reflect comments from Secdir review (Mirja). 1994 B.13. Changes to draft-ietf-lisp-rfc6830bis-17 1996 o Posted September 2018. 1998 o Indicate in the "Changes since RFC 6830" section why the document 1999 has been shortened in length. 2001 o Make reference to RFC 8085 about UDP congestion control. 2003 o More editorial changes from multiple IESG reviews. 2005 B.14. Changes to draft-ietf-lisp-rfc6830bis-16 2007 o Posted late August 2018. 2009 o Distinguish the message type names between ICMP for IPv4 and ICMP 2010 for IPv6 for handling MTU issues. 2012 B.15. Changes to draft-ietf-lisp-rfc6830bis-15 2014 o Posted August 2018. 2016 o Final editorial changes before RFC submission for Proposed 2017 Standard. 2019 o Added section "Changes since RFC 6830" so implementers are 2020 informed of any changes since the last RFC publication. 2022 B.16. Changes to draft-ietf-lisp-rfc6830bis-14 2024 o Posted July 2018 IETF week. 2026 o Put obsolete of RFC 6830 in Intro section in addition to abstract. 2028 B.17. Changes to draft-ietf-lisp-rfc6830bis-13 2030 o Posted March IETF Week 2018. 2032 o Clarified that a new nonce is required per RLOC. 2034 o Removed 'Clock Sweep' section. This text must be placed in a new 2035 OAM document. 2037 o Some references changed from normative to informative 2039 B.18. Changes to draft-ietf-lisp-rfc6830bis-12 2041 o Posted July 2018. 2043 o Fixed Luigi editorial comments to ready draft for RFC status. 2045 B.19. Changes to draft-ietf-lisp-rfc6830bis-11 2047 o Posted March 2018. 2049 o Removed sections 16, 17 and 18 (Mobility, Deployment and 2050 Traceroute considerations). This text must be placed in a new OAM 2051 document. 2053 B.20. Changes to draft-ietf-lisp-rfc6830bis-10 2055 o Posted March 2018. 2057 o Updated section 'Router Locator Selection' stating that the Data- 2058 Plane MUST follow what's stored in the Map-Cache (priorities and 2059 weights). 2061 o Section 'Routing Locator Reachability': Removed bullet point 2 2062 (ICMP Network/Host Unreachable),3 (hints from BGP),4 (ICMP Port 2063 Unreachable),5 (receive a Map-Reply as a response) and RLOC 2064 probing 2066 o Removed 'Solicit-Map Request'. 2068 B.21. Changes to draft-ietf-lisp-rfc6830bis-09 2070 o Posted January 2018. 2072 o Add more details in section 5.3 about DSCP processing during 2073 encapsulation and decapsulation. 2075 o Added clarity to definitions in the Definition of Terms section 2076 from various commenters. 2078 o Removed PA and PI definitions from Definition of Terms section. 2080 o More editorial changes. 2082 o Removed 4342 from IANA section and move to RFC6833 IANA section. 2084 B.22. Changes to draft-ietf-lisp-rfc6830bis-08 2086 o Posted January 2018. 2088 o Remove references to research work for any protocol mechanisms. 2090 o Document scanned to make sure it is RFC 2119 compliant. 2092 o Made changes to reflect comments from document WG shepherd Luigi 2093 Iannone. 2095 o Ran IDNITs on the document. 2097 B.23. Changes to draft-ietf-lisp-rfc6830bis-07 2099 o Posted November 2017. 2101 o Rephrase how Instance-IDs are used and don't refer to [RFC1918] 2102 addresses. 2104 B.24. Changes to draft-ietf-lisp-rfc6830bis-06 2106 o Posted October 2017. 2108 o Put RTR definition before it is used. 2110 o Rename references that are now working group drafts. 2112 o Remove "EIDs MUST NOT be used as used by a host to refer to other 2113 hosts. Note that EID blocks MAY LISP RLOCs". 2115 o Indicate what address-family can appear in data packets. 2117 o ETRs may, rather than will, be the ones to send Map-Replies. 2119 o Recommend, rather than mandate, max encapsulation headers to 2. 2121 o Reference VPN draft when introducing Instance-ID. 2123 o Indicate that SMRs can be sent when ITR/ETR are in the same node. 2125 o Clarify when private addresses can be used. 2127 B.25. Changes to draft-ietf-lisp-rfc6830bis-05 2129 o Posted August 2017. 2131 o Make it clear that a Re-encapsulating Tunnel Router is an RTR. 2133 B.26. Changes to draft-ietf-lisp-rfc6830bis-04 2135 o Posted July 2017. 2137 o Changed reference of IPv6 RFC2460 to RFC8200. 2139 o Indicate that the applicability statement for UDP zero checksums 2140 over IPv6 adheres to RFC6936. 2142 B.27. Changes to draft-ietf-lisp-rfc6830bis-03 2144 o Posted May 2017. 2146 o Move the control-plane related codepoints in the IANA 2147 Considerations section to RFC6833bis. 2149 B.28. Changes to draft-ietf-lisp-rfc6830bis-02 2151 o Posted April 2017. 2153 o Reflect some editorial comments from Damien Sausez. 2155 B.29. Changes to draft-ietf-lisp-rfc6830bis-01 2157 o Posted March 2017. 2159 o Include references to new RFCs published. 2161 o Change references from RFC6833 to RFC6833bis. 2163 o Clarified LCAF text in the IANA section. 2165 o Remove references to "experimental". 2167 B.30. Changes to draft-ietf-lisp-rfc6830bis-00 2169 o Posted December 2016. 2171 o Created working group document from draft-farinacci-lisp 2172 -rfc6830-00 individual submission. No other changes made. 2174 Authors' Addresses 2176 Dino Farinacci 2177 lispers.net 2179 EMail: farinacci@gmail.com 2181 Vince Fuller 2182 vaf.net Internet Consulting 2184 EMail: vince.fuller@gmail.com 2186 Dave Meyer 2187 1-4-5.net 2189 EMail: dmm@1-4-5.net 2191 Darrel Lewis 2192 Cisco Systems 2193 170 Tasman Drive 2194 San Jose, CA 2195 USA 2197 EMail: darlewis@cisco.com 2199 Albert Cabellos 2200 UPC/BarcelonaTech 2201 Campus Nord, C. Jordi Girona 1-3 2202 Barcelona, Catalunya 2203 Spain 2205 EMail: acabello@ac.upc.edu