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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: May 22, 2021 D. Meyer 7 1-4-5.net 8 D. Lewis 9 Cisco Systems 10 A. Cabellos (Ed.) 11 UPC/BarcelonaTech 12 November 18, 2020 14 The Locator/ID Separation Protocol (LISP) 15 draft-ietf-lisp-rfc6830bis-36 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 May 22, 2021. 50 Copyright Notice 52 Copyright (c) 2020 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-27 . . . . . . . . 41 105 B.2. Changes to draft-ietf-lisp-rfc6830bis-27 . . . . . . . . 41 106 B.3. Changes to draft-ietf-lisp-rfc6830bis-26 . . . . . . . . 41 107 B.4. Changes to draft-ietf-lisp-rfc6830bis-25 . . . . . . . . 42 108 B.5. Changes to draft-ietf-lisp-rfc6830bis-24 . . . . . . . . 42 109 B.6. Changes to draft-ietf-lisp-rfc6830bis-23 . . . . . . . . 42 110 B.7. Changes to draft-ietf-lisp-rfc6830bis-22 . . . . . . . . 42 111 B.8. Changes to draft-ietf-lisp-rfc6830bis-21 . . . . . . . . 42 112 B.9. Changes to draft-ietf-lisp-rfc6830bis-20 . . . . . . . . 42 113 B.10. Changes to draft-ietf-lisp-rfc6830bis-19 . . . . . . . . 42 114 B.11. Changes to draft-ietf-lisp-rfc6830bis-18 . . . . . . . . 43 115 B.12. Changes to draft-ietf-lisp-rfc6830bis-17 . . . . . . . . 43 116 B.13. Changes to draft-ietf-lisp-rfc6830bis-16 . . . . . . . . 43 117 B.14. Changes to draft-ietf-lisp-rfc6830bis-15 . . . . . . . . 43 118 B.15. Changes to draft-ietf-lisp-rfc6830bis-14 . . . . . . . . 43 119 B.16. Changes to draft-ietf-lisp-rfc6830bis-13 . . . . . . . . 43 120 B.17. Changes to draft-ietf-lisp-rfc6830bis-12 . . . . . . . . 44 121 B.18. Changes to draft-ietf-lisp-rfc6830bis-11 . . . . . . . . 44 122 B.19. Changes to draft-ietf-lisp-rfc6830bis-10 . . . . . . . . 44 123 B.20. Changes to draft-ietf-lisp-rfc6830bis-09 . . . . . . . . 44 124 B.21. Changes to draft-ietf-lisp-rfc6830bis-08 . . . . . . . . 45 125 B.22. Changes to draft-ietf-lisp-rfc6830bis-07 . . . . . . . . 45 126 B.23. Changes to draft-ietf-lisp-rfc6830bis-06 . . . . . . . . 45 127 B.24. Changes to draft-ietf-lisp-rfc6830bis-05 . . . . . . . . 45 128 B.25. Changes to draft-ietf-lisp-rfc6830bis-04 . . . . . . . . 46 129 B.26. Changes to draft-ietf-lisp-rfc6830bis-03 . . . . . . . . 46 130 B.27. Changes to draft-ietf-lisp-rfc6830bis-02 . . . . . . . . 46 131 B.28. Changes to draft-ietf-lisp-rfc6830bis-01 . . . . . . . . 46 132 B.29. Changes to draft-ietf-lisp-rfc6830bis-00 . . . . . . . . 46 133 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 46 135 1. Introduction 137 This document describes the Locator/Identifier Separation Protocol 138 (LISP). LISP is an encapsulation protocol built around the 139 fundamental idea of separating the topological location of a network 140 attachment point from the node's identity [CHIAPPA]. As a result 141 LISP creates two namespaces: Endpoint Identifiers (EIDs), that are 142 used to identify end-hosts (e.g., nodes or Virtual Machines) and 143 routable Routing Locators (RLOCs), used to identify network 144 attachment points. LISP then defines functions for mapping between 145 the two namespaces and for encapsulating traffic originated by 146 devices using non-routable EIDs for transport across a network 147 infrastructure that routes and forwards using RLOCs. LISP 148 encapsulation uses a dynamic form of tunneling where no static 149 provisioning is required or necessary. 151 LISP is an overlay protocol that separates control from Data-Plane, 152 this document specifies the Data-Plane as well as how LISP-capable 153 routers (Tunnel Routers) exchange packets by encapsulating them to 154 the appropriate location. Tunnel routers are equipped with a cache, 155 called Map-Cache, that contains EID-to-RLOC mappings. The Map-Cache 156 is populated using the LISP Control-Plane protocol 157 [I-D.ietf-lisp-rfc6833bis]. 159 LISP does not require changes to either the host protocol stack or to 160 underlay routers. By separating the EID from the RLOC space, LISP 161 offers native Traffic Engineering, multihoming and mobility, among 162 other features. 164 Creation of LISP was initially motivated by discussions during the 165 IAB-sponsored Routing and Addressing Workshop held in Amsterdam in 166 October 2006 (see [RFC4984]). 168 This document specifies the LISP Data-Plane encapsulation and other 169 LISP forwarding node functionality while [I-D.ietf-lisp-rfc6833bis] 170 specifies the LISP control plane. LISP deployment guidelines can be 171 found in [RFC7215] and [RFC6835] describes considerations for network 172 operational management. Finally, [I-D.ietf-lisp-introduction] 173 describes the LISP architecture. 175 This document obsoletes RFC 6830. 177 1.1. Scope of Applicability 179 LISP was originally developed to address the Internet-wide route 180 scaling problem [RFC4984]. While there are a number of approaches of 181 interest for that problem, as LISP as been developed and refined, a 182 large number of other LISP uses have been found and are being used. 183 As such, the design and development of LISP has changed so as to 184 focus on these use cases. The common property of these uses is a 185 large set of cooperating entities seeking to communicate over the 186 public Internet or other large underlay IP infrastructures, while 187 keeping the addressing and topology of the cooperating entities 188 separate from the underlay and Internet topology, routing, and 189 addressing. 191 2. Requirements Notation 193 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 194 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 195 "OPTIONAL" in this document are to be interpreted as described in BCP 196 14 [RFC2119] [RFC8174] when, and only when, they appear in all 197 capitals, as shown here. 199 3. Definition of Terms 201 Address Family Identifier (AFI): AFI is a term used to describe an 202 address encoding in a packet. An address family that pertains to 203 addresses found in Data-Plane headers. See [AFN] and [RFC3232] 204 for details. An AFI value of 0 used in this specification 205 indicates an unspecified encoded address where the length of the 206 address is 0 octets following the 16-bit AFI value of 0. 208 Anycast Address: Anycast Address refers to the same IPv4 or IPv6 209 address configured and used on multiple systems at the same time. 210 An EID or RLOC can be an anycast address in each of their own 211 address spaces. 213 Client-side: Client-side is a term used in this document to indicate 214 a connection initiation attempt by an end-system represented by an 215 EID. 217 Egress Tunnel Router (ETR): An ETR is a router that accepts an IP 218 packet where the destination address in the "outer" IP header is 219 one of its own RLOCs. The router strips the "outer" header and 220 forwards the packet based on the next IP header found. In 221 general, an ETR receives LISP-encapsulated IP packets from the 222 Internet on one side and sends decapsulated IP packets to site 223 end-systems on the other side. ETR functionality does not have to 224 be limited to a router device. A server host can be the endpoint 225 of a LISP tunnel as well. 227 EID-to-RLOC Database: The EID-to-RLOC Database is a distributed 228 database that contains all known EID-Prefix-to-RLOC mappings. 229 Each potential ETR typically contains a small piece of the 230 database: the EID-to-RLOC mappings for the EID-Prefixes "behind" 231 the router. These map to one of the router's own IP addresses 232 that are routable on the underlay. Note that there MAY be 233 transient conditions when the EID-Prefix for the LISP site and 234 Locator-Set for each EID-Prefix may not be the same on all ETRs. 235 This has no negative implications, since a partial set of Locators 236 can be used. 238 EID-to-RLOC Map-Cache: The EID-to-RLOC Map-Cache is generally 239 short-lived, on-demand table in an ITR that stores, tracks, and is 240 responsible for timing out and otherwise validating EID-to-RLOC 241 mappings. This cache is distinct from the full "database" of EID- 242 to-RLOC mappings; it is dynamic, local to the ITR(s), and 243 relatively small, while the database is distributed, relatively 244 static, and much more widely scoped to LISP nodes. 246 EID-Prefix: An EID-Prefix is a power-of-two block of EIDs that are 247 allocated to a site by an address allocation authority. EID- 248 Prefixes are associated with a set of RLOC addresses. EID-Prefix 249 allocations can be broken up into smaller blocks when an RLOC set 250 is to be associated with the larger EID-Prefix block. 252 End-System: An end-system is an IPv4 or IPv6 device that originates 253 packets with a single IPv4 or IPv6 header. The end-system 254 supplies an EID value for the destination address field of the IP 255 header when communicating outside of its routing domain. An end- 256 system can be a host computer, a switch or router device, or any 257 network appliance. 259 Endpoint ID (EID): An EID is a 32-bit (for IPv4) or 128-bit (for 260 IPv6) value that identifies a host. EIDs are generally only found 261 in the source and destination address fields of the first (most 262 inner) LISP header of a packet. The host obtains a destination 263 EID the same way it obtains a destination address today, for 264 example, through a Domain Name System (DNS) [RFC1034] lookup or 265 Session Initiation Protocol (SIP) [RFC3261] exchange. The source 266 EID is obtained via existing mechanisms used to set a host's 267 "local" IP address. An EID used on the public Internet MUST have 268 the same properties as any other IP address used in that manner; 269 this means, among other things, that it MUST be unique. An EID is 270 allocated to a host from an EID-Prefix block associated with the 271 site where the host is located. An EID can be used by a host to 272 refer to other hosts. Note that EID blocks MAY be assigned in a 273 hierarchical manner, independent of the network topology, to 274 facilitate scaling of the mapping database. In addition, an EID 275 block assigned to a site MAY have site-local structure 276 (subnetting) for routing within the site; this structure is not 277 visible to the underlay routing system. In theory, the bit string 278 that represents an EID for one device can represent an RLOC for a 279 different device. When used in discussions with other Locator/ID 280 separation proposals, a LISP EID will be called an "LEID". 281 Throughout this document, any references to "EID" refer to an 282 LEID. 284 Ingress Tunnel Router (ITR): An ITR is a router that resides in a 285 LISP site. Packets sent by sources inside of the LISP site to 286 destinations outside of the site are candidates for encapsulation 287 by the ITR. The ITR treats the IP destination address as an EID 288 and performs an EID-to-RLOC mapping lookup. The router then 289 prepends an "outer" IP header with one of its routable RLOCs (in 290 the RLOC space) in the source address field and the result of the 291 mapping lookup in the destination address field. Note that this 292 destination RLOC may be an intermediate, proxy device that has 293 better knowledge of the EID-to-RLOC mapping closer to the 294 destination EID. In general, an ITR receives IP packets from site 295 end-systems on one side and sends LISP-encapsulated IP packets 296 toward the Internet on the other side. 298 LISP Header: LISP header is a term used in this document to refer 299 to the outer IPv4 or IPv6 header, a UDP header, and a LISP- 300 specific 8-octet header that follow the UDP header and that an ITR 301 prepends or an ETR strips. 303 LISP Router: A LISP router is a router that performs the functions 304 of any or all of the following: ITR, ETR, RTR, Proxy-ITR (PITR), 305 or Proxy-ETR (PETR). 307 LISP Site: LISP site is a set of routers in an edge network that are 308 under a single technical administration. LISP routers that reside 309 in the edge network are the demarcation points to separate the 310 edge network from the core network. 312 Locator-Status-Bits (LSBs): Locator-Status-Bits are present in the 313 LISP header. They are used by ITRs to inform ETRs about the up/ 314 down status of all ETRs at the local site. These bits are used as 315 a hint to convey up/down router status and not path reachability 316 status. The LSBs can be verified by use of one of the Locator 317 reachability algorithms described in Section 10. An ETR MUST 318 rate-limit the action it takes when it detects changes in the 319 Locator-Status-Bits. 321 Proxy-ETR (PETR): A PETR is defined and described in [RFC6832]. A 322 PETR acts like an ETR but does so on behalf of LISP sites that 323 send packets to destinations at non-LISP sites. 325 Proxy-ITR (PITR): A PITR is defined and described in [RFC6832]. A 326 PITR acts like an ITR but does so on behalf of non-LISP sites that 327 send packets to destinations at LISP sites. 329 Recursive Tunneling: Recursive Tunneling occurs when a packet has 330 more than one LISP IP header. Additional layers of tunneling MAY 331 be employed to implement Traffic Engineering or other re-routing 332 as needed. When this is done, an additional "outer" LISP header 333 is added, and the original RLOCs are preserved in the "inner" 334 header. 336 Re-Encapsulating Tunneling Router (RTR): An RTR acts like an ETR to 337 remove a LISP header, then acts as an ITR to prepend a new LISP 338 header. This is known as Re-encapsulating Tunneling. Doing this 339 allows a packet to be re-routed by the RTR without adding the 340 overhead of additional tunnel headers. When using multiple 341 mapping database systems, care must be taken to not create re- 342 encapsulation loops through misconfiguration. 344 Route-Returnability: Route-returnability is an assumption that the 345 underlying routing system will deliver packets to the destination. 346 When combined with a nonce that is provided by a sender and 347 returned by a receiver, this limits off-path data insertion. A 348 route-returnability check is verified when a message is sent with 349 a nonce, another message is returned with the same nonce, and the 350 destination of the original message appears as the source of the 351 returned message. 353 Routing Locator (RLOC): An RLOC is an IPv4 [RFC0791] or IPv6 354 [RFC8200] address of an Egress Tunnel Router (ETR). An RLOC is 355 the output of an EID-to-RLOC mapping lookup. An EID maps to zero 356 or more RLOCs. Typically, RLOCs are numbered from blocks that are 357 assigned to a site at each point to which it attaches to the 358 underlay network; where the topology is defined by the 359 connectivity of provider networks. Multiple RLOCs can be assigned 360 to the same ETR device or to multiple ETR devices at a site. 362 Server-side: Server-side is a term used in this document to indicate 363 that a connection initiation attempt is being accepted for a 364 destination EID. 366 xTR: An xTR is a reference to an ITR or ETR when direction of data 367 flow is not part of the context description. "xTR" refers to the 368 router that is the tunnel endpoint and is used synonymously with 369 the term "Tunnel Router". For example, "An xTR can be located at 370 the Customer Edge (CE) router" indicates both ITR and ETR 371 functionality at the CE router. 373 4. Basic Overview 375 One key concept of LISP is that end-systems operate the same way they 376 do today. The IP addresses that hosts use for tracking sockets and 377 connections, and for sending and receiving packets, do not change. 378 In LISP terminology, these IP addresses are called Endpoint 379 Identifiers (EIDs). 381 Routers continue to forward packets based on IP destination 382 addresses. When a packet is LISP encapsulated, these addresses are 383 referred to as Routing Locators (RLOCs). Most routers along a path 384 between two hosts will not change; they continue to perform routing/ 385 forwarding lookups on the destination addresses. For routers between 386 the source host and the ITR as well as routers from the ETR to the 387 destination host, the destination address is an EID. For the routers 388 between the ITR and the ETR, the destination address is an RLOC. 390 Another key LISP concept is the "Tunnel Router". A Tunnel Router 391 prepends LISP headers on host-originated packets and strips them 392 prior to final delivery to their destination. The IP addresses in 393 this "outer header" are RLOCs. During end-to-end packet exchange 394 between two Internet hosts, an ITR prepends a new LISP header to each 395 packet, and an ETR strips the new header. The ITR performs EID-to- 396 RLOC lookups to determine the routing path to the ETR, which has the 397 RLOC as one of its IP addresses. 399 Some basic rules governing LISP are: 401 o End-systems only send to addresses that are EIDs. EIDs are 402 typically IP addresses assigned to hosts (other types of EID are 403 supported by LISP, see [RFC8060] for further information). End- 404 systems don't know that addresses are EIDs versus RLOCs but assume 405 that packets get to their intended destinations. In a system 406 where LISP is deployed, LISP routers intercept EID-addressed 407 packets and assist in delivering them across the network core 408 where EIDs cannot be routed. The procedure a host uses to send IP 409 packets does not change. 411 o LISP routers mostly deal with Routing Locator addresses. See 412 details in Section 4.2 to clarify what is meant by "mostly". 414 o RLOCs are always IP addresses assigned to routers, preferably 415 topologically oriented addresses from provider CIDR (Classless 416 Inter-Domain Routing) blocks. 418 o When a router originates packets, it MAY use as a source address 419 either an EID or RLOC. When acting as a host (e.g., when 420 terminating a transport session such as Secure SHell (SSH), 421 TELNET, or the Simple Network Management Protocol (SNMP)), it MAY 422 use an EID that is explicitly assigned for that purpose. An EID 423 that identifies the router as a host MUST NOT be used as an RLOC; 424 an EID is only routable within the scope of a site. A typical BGP 425 configuration might demonstrate this "hybrid" EID/RLOC usage where 426 a router could use its "host-like" EID to terminate iBGP sessions 427 to other routers in a site while at the same time using RLOCs to 428 terminate eBGP sessions to routers outside the site. 430 o Packets with EIDs in them are not expected to be delivered end-to- 431 end in the absence of an EID-to-RLOC mapping operation. They are 432 expected to be used locally for intra-site communication or to be 433 encapsulated for inter-site communication. 435 o EIDs MAY also be structured (subnetted) in a manner suitable for 436 local routing within an Autonomous System (AS). 438 An additional LISP header MAY be prepended to packets by a TE-ITR 439 when re-routing of the path for a packet is desired. A potential 440 use-case for this would be an ISP router that needs to perform 441 Traffic Engineering for packets flowing through its network. In such 442 a situation, termed "Recursive Tunneling", an ISP transit acts as an 443 additional ITR, and the destination RLOC it uses for the new 444 prepended header would be either a TE-ETR within the ISP (along an 445 intra-ISP traffic engineered path) or a TE-ETR within another ISP (an 446 inter-ISP traffic engineered path, where an agreement to build such a 447 path exists). 449 In order to avoid excessive packet overhead as well as possible 450 encapsulation loops, this document RECOMMENDS that a maximum of two 451 LISP headers can be prepended to a packet. For initial LISP 452 deployments, it is assumed that two headers is sufficient, where the 453 first prepended header is used at a site for Location/Identity 454 separation and the second prepended header is used inside a service 455 provider for Traffic Engineering purposes. 457 Tunnel Routers can be placed fairly flexibly in a multi-AS topology. 458 For example, the ITR for a particular end-to-end packet exchange 459 might be the first-hop or default router within a site for the source 460 host. Similarly, the ETR might be the last-hop router directly 461 connected to the destination host. Another example, perhaps for a 462 VPN service outsourced to an ISP by a site, the ITR could be the 463 site's border router at the service provider attachment point. 464 Mixing and matching of site-operated, ISP-operated, and other Tunnel 465 Routers is allowed for maximum flexibility. 467 4.1. Deployment on the Public Internet 469 Several of the mechanisms in this document are intended for 470 deployment in controlled, trusted environments, and are insecure for 471 use over the public Internet. In particular, on the public internet 472 xTRs: 474 o MUST set the N, L, E, and V bits in the LISP header (Section 5.1) 475 to zero. 477 o MUST NOT use Locator-Status-Bits and echo-nonce, as described in 478 Section 10 for Routing Locator Reachability. Instead MUST rely 479 solely on control-plane methods. 481 o MUST NOT use Gleaning or Locator-Status-Bits and Map-Versioning, 482 as described in Section 13 to update the EID-to-RLOC Mappings. 483 Instead relying solely on control-plane methods. 485 4.2. Packet Flow Sequence 487 This section provides an example of the unicast packet flow, 488 including also Control-Plane information as specified in 489 [I-D.ietf-lisp-rfc6833bis]. The example also assumes the following 490 conditions: 492 o Source host "host1.abc.example.com" is sending a packet to 493 "host2.xyz.example.com", exactly as it would if the site was not 494 not using LISP. 496 o Each site is multihomed, so each Tunnel Router has an address 497 (RLOC) assigned from the service provider address block for each 498 provider to which that particular Tunnel Router is attached. 500 o The ITR(s) and ETR(s) are directly connected to the source and 501 destination, respectively, but the source and destination can be 502 located anywhere in the LISP site. 504 o A Map-Request is sent for an external destination when the 505 destination is not found in the forwarding table or matches a 506 default route. Map-Requests are sent to the mapping database 507 system by using the LISP Control-Plane protocol documented in 508 [I-D.ietf-lisp-rfc6833bis]. 510 o Map-Replies are sent on the underlying routing system topology 511 using the [I-D.ietf-lisp-rfc6833bis] Control-Plane protocol. 513 Client host1.abc.example.com wants to communicate with server 514 host2.xyz.example.com: 516 1. host1.abc.example.com wants to open a TCP connection to 517 host2.xyz.example.com. It does a DNS lookup on 518 host2.xyz.example.com. An A/AAAA record is returned. This 519 address is the destination EID. The locally assigned address of 520 host1.abc.example.com is used as the source EID. An IPv4 or IPv6 521 packet is built and forwarded through the LISP site as a normal 522 IP packet until it reaches a LISP ITR. 524 2. The LISP ITR must be able to map the destination EID to an RLOC 525 of one of the ETRs at the destination site. A method to do this 526 is to send a LISP Map-Request, as specified in 527 [I-D.ietf-lisp-rfc6833bis]. 529 3. The mapping system helps forwarding the Map-Request to the 530 corresponding ETR. When the Map-Request arrives at one of the 531 ETRs at the destination site, it will process the packet as a 532 control message. 534 4. The ETR looks at the destination EID of the Map-Request and 535 matches it against the prefixes in the ETR's configured EID-to- 536 RLOC mapping database. This is the list of EID-Prefixes the ETR 537 is supporting for the site it resides in. If there is no match, 538 the Map-Request is dropped. Otherwise, a LISP Map-Reply is 539 returned to the ITR. 541 5. The ITR receives the Map-Reply message, parses the message, and 542 stores the mapping information from the packet. This information 543 is stored in the ITR's EID-to-RLOC Map-Cache. Note that the Map- 544 Cache is an on-demand cache. An ITR will manage its Map-Cache in 545 such a way that optimizes for its resource constraints. 547 6. Subsequent packets from host1.abc.example.com to 548 host2.xyz.example.com will have a LISP header prepended by the 549 ITR using the appropriate RLOC as the LISP header destination 550 address learned from the ETR. Note that the packet MAY be sent 551 to a different ETR than the one that returned the Map-Reply due 552 to the source site's hashing policy or the destination site's 553 Locator-Set policy. 555 7. The ETR receives these packets directly (since the destination 556 address is one of its assigned IP addresses), checks the validity 557 of the addresses, strips the LISP header, and forwards packets to 558 the attached destination host. 560 8. In order to defer the need for a mapping lookup in the reverse 561 direction, an ETR can OPTIONALLY create a cache entry that maps 562 the source EID (inner-header source IP address) to the source 563 RLOC (outer-header source IP address) in a received LISP packet. 564 Such a cache entry is termed a "glean mapping" and only contains 565 a single RLOC for the EID in question. More complete information 566 about additional RLOCs SHOULD be verified by sending a LISP Map- 567 Request for that EID. Both the ITR and the ETR MAY also 568 influence the decision the other makes in selecting an RLOC. 570 5. LISP Encapsulation Details 572 Since additional tunnel headers are prepended, the packet becomes 573 larger and can exceed the MTU of any link traversed from the ITR to 574 the ETR. It is RECOMMENDED in IPv4 that packets do not get 575 fragmented as they are encapsulated by the ITR. Instead, the packet 576 is dropped and an ICMP Unreachable/Fragmentation-Needed message is 577 returned to the source. 579 In the case when fragmentation is needed, this specification 580 RECOMMENDS that implementations provide support for one of the 581 proposed fragmentation and reassembly schemes. Two existing schemes 582 are detailed in Section 7. 584 Since IPv4 or IPv6 addresses can be either EIDs or RLOCs, the LISP 585 architecture supports IPv4 EIDs with IPv6 RLOCs (where the inner 586 header is in IPv4 packet format and the outer header is in IPv6 587 packet format) or IPv6 EIDs with IPv4 RLOCs (where the inner header 588 is in IPv6 packet format and the outer header is in IPv4 packet 589 format). The next sub-sections illustrate packet formats for the 590 homogeneous case (IPv4-in-IPv4 and IPv6-in-IPv6), but all 4 591 combinations MUST be supported. Additional types of EIDs are defined 592 in [RFC8060]. 594 As LISP uses UDP encapsulation to carry traffic between xTRs across 595 the Internet, implementors should be aware of the provisions of 596 [RFC8085], especially those given in section 3.1.11 on congestion 597 control for UDP tunneling. 599 Implementors are encouraged to consider UDP checksum usage guidelines 600 in section 3.4 of [RFC8085] when it is desirable to protect UDP and 601 LISP headers against corruption. 603 5.1. LISP IPv4-in-IPv4 Header Format 604 0 1 2 3 605 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 1 606 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 607 / |Version| IHL | DSCP |ECN| Total Length | 608 / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 609 | | Identification |Flags| Fragment Offset | 610 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 611 OH | Time to Live | Protocol = 17 | Header Checksum | 612 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 613 | | Source Routing Locator | 614 \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 615 \ | Destination Routing Locator | 616 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 617 / | Source Port = xxxx | Dest Port = 4341 | 618 UDP +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 619 \ | UDP Length | UDP Checksum | 620 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 621 L |N|L|E|V|I|R|K|K| Nonce/Map-Version | 622 I \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 623 S / | Instance ID/Locator-Status-Bits | 624 P +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 625 / |Version| IHL | DSCP |ECN| Total Length | 626 / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 627 | | Identification |Flags| Fragment Offset | 628 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 629 IH | Time to Live | Protocol | Header Checksum | 630 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 631 | | Source EID | 632 \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 633 \ | Destination EID | 634 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 636 IHL = IP-Header-Length 638 5.2. LISP IPv6-in-IPv6 Header Format 640 0 1 2 3 641 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 1 642 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 643 / |Version| DSCP |ECN| Flow Label | 644 / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 645 | | Payload Length | Next Header=17| Hop Limit | 646 v +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 647 | | 648 O + + 649 u | | 650 t + Source Routing Locator + 651 e | | 652 r + + 653 | | 654 H +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 655 d | | 656 r + + 657 | | 658 ^ + Destination Routing Locator + 659 | | | 660 \ + + 661 \ | | 662 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 663 / | Source Port = xxxx | Dest Port = 4341 | 664 UDP +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 665 \ | UDP Length | UDP Checksum | 666 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 667 L |N|L|E|V|I|R|K|K| Nonce/Map-Version | 668 I \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 669 S / | Instance ID/Locator-Status-Bits | 670 P +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 671 / |Version| DSCP |ECN| Flow Label | 672 / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 673 / | Payload Length | Next Header | Hop Limit | 674 v +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 675 | | 676 I + + 677 n | | 678 n + Source EID + 679 e | | 680 r + + 681 | | 682 H +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 683 d | | 684 r + + 685 | | 686 ^ + Destination EID + 687 \ | | 688 \ + + 689 \ | | 690 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 692 5.3. Tunnel Header Field Descriptions 694 Inner Header (IH): The inner header is the header on the 695 datagram received from the originating host [RFC0791] [RFC8200] 696 [RFC2474]. The source and destination IP addresses are EIDs. 698 Outer Header: (OH) The outer header is a new header prepended by an 699 ITR. The address fields contain RLOCs obtained from the ingress 700 router's EID-to-RLOC Cache. The IP protocol number is "UDP (17)" 701 from [RFC0768]. The setting of the Don't Fragment (DF) bit 702 'Flags' field is according to rules listed in Sections 7.1 and 703 7.2. 705 UDP Header: The UDP header contains an ITR selected source port when 706 encapsulating a packet. See Section 12 for details on the hash 707 algorithm used to select a source port based on the 5-tuple of the 708 inner header. The destination port MUST be set to the well-known 709 IANA-assigned port value 4341. 711 UDP Checksum: The 'UDP Checksum' field SHOULD be transmitted as zero 712 by an ITR for either IPv4 [RFC0768] and IPv6 encapsulation 713 [RFC6935] [RFC6936]. When a packet with a zero UDP checksum is 714 received by an ETR, the ETR MUST accept the packet for 715 decapsulation. When an ITR transmits a non-zero value for the UDP 716 checksum, it MUST send a correctly computed value in this field. 717 When an ETR receives a packet with a non-zero UDP checksum, it MAY 718 choose to verify the checksum value. If it chooses to perform 719 such verification, and the verification fails, the packet MUST be 720 silently dropped. If the ETR chooses not to perform the 721 verification, or performs the verification successfully, the 722 packet MUST be accepted for decapsulation. The handling of UDP 723 zero checksums over IPv6 for all tunneling protocols, including 724 LISP, is subject to the applicability statement in [RFC6936]. 726 UDP Length: The 'UDP Length' field is set for an IPv4-encapsulated 727 packet to be the sum of the inner-header IPv4 Total Length plus 728 the UDP and LISP header lengths. For an IPv6-encapsulated packet, 729 the 'UDP Length' field is the sum of the inner-header IPv6 Payload 730 Length, the size of the IPv6 header (40 octets), and the size of 731 the UDP and LISP headers. 733 N: The N-bit is the nonce-present bit. When this bit is set to 1, 734 the low-order 24 bits of the first 32 bits of the LISP header 735 contain a Nonce. See Section 10.1 for details. Both N- and 736 V-bits MUST NOT be set in the same packet. If they are, a 737 decapsulating ETR MUST treat the 'Nonce/Map-Version' field as 738 having a Nonce value present. 740 L: The L-bit is the 'Locator-Status-Bits' field enabled bit. When 741 this bit is set to 1, the Locator-Status-Bits in the second 742 32 bits of the LISP header are in use. 744 x 1 x x 0 x x x 745 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 746 |N|L|E|V|I|R|K|K| Nonce/Map-Version | 747 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 748 | Locator-Status-Bits | 749 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 751 E: The E-bit is the echo-nonce-request bit. This bit MUST be ignored 752 and has no meaning when the N-bit is set to 0. When the N-bit is 753 set to 1 and this bit is set to 1, an ITR is requesting that the 754 nonce value in the 'Nonce' field be echoed back in LISP- 755 encapsulated packets when the ITR is also an ETR. See 756 Section 10.1 for details. 758 V: The V-bit is the Map-Version present bit. When this bit is set to 759 1, the N-bit MUST be 0. Refer to Section 13.2 for more details. 760 This bit indicates that the LISP header is encoded in this 761 case as: 763 0 x 0 1 x x x x 764 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 765 |N|L|E|V|I|R|K|K| Source Map-Version | Dest Map-Version | 766 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 767 | Instance ID/Locator-Status-Bits | 768 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 770 I: The I-bit is the Instance ID bit. See Section 8 for more details. 771 When this bit is set to 1, the 'Locator-Status-Bits' field is 772 reduced to 8 bits and the high-order 24 bits are used as an 773 Instance ID. If the L-bit is set to 0, then the low-order 8 bits 774 are transmitted as zero and ignored on receipt. The format of the 775 LISP header would look like this: 777 x x x x 1 x x x 778 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 779 |N|L|E|V|I|R|K|K| Nonce/Map-Version | 780 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 781 | Instance ID | LSBs | 782 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 784 R: The R-bit is a Reserved and unassigned bit for future use. It 785 MUST be set to 0 on transmit and MUST be ignored on receipt. 787 KK: The KK-bits are a 2-bit field used when encapsulated packets are 788 encrypted. The field is set to 00 when the packet is not 789 encrypted. See [RFC8061] for further information. 791 LISP Nonce: The LISP 'Nonce' field is a 24-bit value that is 792 randomly generated by an ITR when the N-bit is set to 1. Nonce 793 generation algorithms are an implementation matter but are 794 required to generate different nonces when sending to different 795 RLOCs. The nonce is also used when the E-bit is set to request 796 the nonce value to be echoed by the other side when packets are 797 returned. When the E-bit is clear but the N-bit is set, a remote 798 ITR is either echoing a previously requested echo-nonce or 799 providing a random nonce. See Section 10.1 for more details. 800 Finally, when both the N and V-bit are not set (N=0, V=0), then 801 both the Nonce and Map-Version fields are set to 0 and ignored on 802 receipt. 804 LISP Locator-Status-Bits (LSBs): When the L-bit is also set, the 805 'Locator-Status-Bits' field in the LISP header is set by an ITR to 806 indicate to an ETR the up/down status of the Locators in the 807 source site. Each RLOC in a Map-Reply is assigned an ordinal 808 value from 0 to n-1 (when there are n RLOCs in a mapping entry). 809 The Locator-Status-Bits are numbered from 0 to n-1 from the least 810 significant bit of the field. The field is 32 bits when the I-bit 811 is set to 0 and is 8 bits when the I-bit is set to 1. When a 812 Locator-Status-Bit is set to 1, the ITR is indicating to the ETR 813 that the RLOC associated with the bit ordinal has up status. See 814 Section 10 for details on how an ITR can determine the status of 815 the ETRs at the same site. When a site has multiple EID-Prefixes 816 that result in multiple mappings (where each could have a 817 different Locator-Set), the Locator-Status-Bits setting in an 818 encapsulated packet MUST reflect the mapping for the EID-Prefix 819 that the inner-header source EID address matches (longest-match). 820 If the LSB for an anycast Locator is set to 1, then there is at 821 least one RLOC with that address, and the ETR is considered 'up'. 823 When doing ITR/PITR encapsulation: 825 o The outer-header 'Time to Live' field (or 'Hop Limit' field, in 826 the case of IPv6) SHOULD be copied from the inner-header 'Time to 827 Live' field. 829 o The outer-header IPv4 'Differentiated Services Code Point' (DSCP) 830 field or the 'Traffic Class' field, in the case of IPv6, SHOULD be 831 copied from the inner-header IPv4 DSCP field or 'Traffic Class' 832 field in the case of IPv6, to the outer-header. Guidelines for 833 this can be found at [RFC2983]. 835 o The IPv4 'Explicit Congestion Notification' (ECN) field and bits 6 836 and 7 of the IPv6 'Traffic Class' field requires special treatment 837 in order to avoid discarding indications of congestion as 838 specified in [RFC6040]. 840 When doing ETR/PETR decapsulation: 842 o The inner-header IPv4 'Time to Live' field or 'Hop Limit' field in 843 the case of IPv6, MUST be copied from the outer-header 'Time to 844 Live'/'Hop Limit' field, when the 'Time to Live'/'Hop Limit' value 845 of the outer header is less than the 'Time to Live'/'Hop Limit' 846 value of the inner header. Failing to perform this check can 847 cause the 'Time to Live'/'Hop Limit' of the inner header to 848 increment across encapsulation/decapsulation cycles. This check 849 is also performed when doing initial encapsulation, when a packet 850 comes to an ITR or PITR destined for a LISP site. 852 o The outer-header IPv4 'Differentiated Services Code Point' (DSCP) 853 field or the 'Traffic Class' field in the case of IPv6, SHOULD be 854 copied from the outer-header IPv4 DSCP field or 'Traffic Class' 855 field in the case of IPv6, to the inner-header. Guidelines for 856 this can be found at [RFC2983]. 858 o The IPv4 'Explicit Congestion Notification' (ECN) field and bits 6 859 and 7 of the IPv6 'Traffic Class' field, requires special 860 treatment in order to avoid discarding indications of congestion 861 as specified in [RFC6040]. Note that implementations exist that 862 copy the 'ECN' field from the outer header to the inner header 863 even though [RFC6040] does not recommend this behavior. It is 864 RECOMMENDED that implementations change to support the behavior in 865 [RFC6040]. 867 Note that if an ETR/PETR is also an ITR/PITR and chooses to re- 868 encapsulate after decapsulating, the net effect of this is that the 869 new outer header will carry the same Time to Live as the old outer 870 header minus 1. 872 Copying the Time to Live (TTL) serves two purposes: first, it 873 preserves the distance the host intended the packet to travel; 874 second, and more importantly, it provides for suppression of looping 875 packets in the event there is a loop of concatenated tunnels due to 876 misconfiguration. 878 Some xTRs and PxTRs performs re-encapsulation operations and need to 879 treat the 'Explicit Congestion Notification' (ECN) in a special way. 880 Because the re-encapsulation operation is a sequence of two 881 operations, namely a decapsulation followed by an encapsulation, the 882 ECN bits MUST be treated as described above for these two operations. 884 The LISP dataplane protocol is not backwards compatible with 885 [RFC6830] and does not have explicit support for introducing future 886 protocol changes (e.g. an explicit version field). However, the LISP 887 control plane [I-D.ietf-lisp-rfc6833bis] allows an ETR to register 888 dataplane capabilities by means of new LCAF types [RFC8060]. In this 889 way an ITR can be made aware of the dataplane capabilities of an ETR, 890 and encapsulate accordingly. The specification of the new LCAF 891 types, new LCAF mechanisms, and their use, is out of the scope of 892 this document. 894 6. LISP EID-to-RLOC Map-Cache 896 ITRs and PITRs maintain an on-demand cache, referred as LISP EID-to- 897 RLOC Map-Cache, that contains mappings from EID-prefixes to locator 898 sets. The cache is used to encapsulate packets from the EID space to 899 the corresponding RLOC network attachment point. 901 When an ITR/PITR receives a packet from inside of the LISP site to 902 destinations outside of the site a longest-prefix match lookup of the 903 EID is done to the Map-Cache. 905 When the lookup succeeds, the Locator-Set retrieved from the Map- 906 Cache is used to send the packet to the EID's topological location. 908 If the lookup fails, the ITR/PITR needs to retrieve the mapping using 909 the LISP Control-Plane protocol [I-D.ietf-lisp-rfc6833bis]. While 910 the mapping is being retrieved, the ITR/PITR can either drop or 911 buffer the packets. This document does not have specific 912 recommendations about the action to be taken. It is up to the 913 deployer to consider whether or not it is desirable to buffer packets 914 and deploy a LISP implementation that offers the desired behaviour. 915 Once the mapping is resolved it is then stored in the local Map-Cache 916 to forward subsequent packets addressed to the same EID-prefix. 918 The Map-Cache is a local cache of mappings, entries are expired based 919 on the associated Time to live. In addition, entries can be updated 920 with more current information, see Section 13 for further information 921 on this. Finally, the Map-Cache also contains reachability 922 information about EIDs and RLOCs, and uses LISP reachability 923 information mechanisms to determine the reachability of RLOCs, see 924 Section 10 for the specific mechanisms. 926 7. Dealing with Large Encapsulated Packets 928 This section proposes two mechanisms to deal with packets that exceed 929 the path MTU between the ITR and ETR. 931 It is left to the implementor to decide if the stateless or stateful 932 mechanism SHOULD be implemented. Both or neither can be used, since 933 it is a local decision in the ITR regarding how to deal with MTU 934 issues, and sites can interoperate with differing mechanisms. 936 Both stateless and stateful mechanisms also apply to Re-encapsulating 937 and Recursive Tunneling, so any actions below referring to an ITR 938 also apply to a TE-ITR. 940 7.1. A Stateless Solution to MTU Handling 942 An ITR stateless solution to handle MTU issues is described as 943 follows: 945 1. Define H to be the size, in octets, of the outer header an ITR 946 prepends to a packet. This includes the UDP and LISP header 947 lengths. 949 2. Define L to be the size, in octets, of the maximum-sized packet 950 an ITR can send to an ETR without the need for the ITR or any 951 intermediate routers to fragment the packet. The network 952 administrator of the LISP deployment has to determine what is the 953 suitable value of L so to make sure that no MTU issues arise. 955 3. Define an architectural constant S for the maximum size of a 956 packet, in octets, an ITR MUST receive from the source so the 957 effective MTU can be met. That is, L = S + H. 959 When an ITR receives a packet from a site-facing interface and adds H 960 octets worth of encapsulation to yield a packet size greater than L 961 octets (meaning the received packet size was greater than S octets 962 from the source), it resolves the MTU issue by first splitting the 963 original packet into 2 equal-sized fragments. A LISP header is then 964 prepended to each fragment. The size of the encapsulated fragments 965 is then (S/2 + H), which is less than the ITR's estimate of the path 966 MTU between the ITR and its correspondent ETR. 968 When an ETR receives encapsulated fragments, it treats them as two 969 individually encapsulated packets. It strips the LISP headers and 970 then forwards each fragment to the destination host of the 971 destination site. The two fragments are reassembled at the 972 destination host into the single IP datagram that was originated by 973 the source host. Note that reassembly can happen at the ETR if the 974 encapsulated packet was fragmented at or after the ITR. 976 This behavior MUST be performed by the ITR only when the source host 977 originates a packet with the 'DF' field of the IP header set to 0. 978 When the 'DF' field of the IP header is set to 1, or the packet is an 979 IPv6 packet originated by the source host, the ITR will drop the 980 packet when the size (adding in the size of the encapsulation header) 981 is greater than L and send an ICMPv4 ICMP Unreachable/Fragmentation- 982 Needed or ICMPv6 "Packet Too Big" message to the source with a value 983 of S, where S is (L - H). 985 When the outer-header encapsulation uses an IPv4 header, an 986 implementation SHOULD set the DF bit to 1 so ETR fragment reassembly 987 can be avoided. An implementation MAY set the DF bit in such headers 988 to 0 if it has good reason to believe there are unresolvable path MTU 989 issues between the sending ITR and the receiving ETR. 991 This specification RECOMMENDS that L be defined as 1500. Additional 992 information about in-network MTU and fragmentation issues can be 993 found at [RFC4459]. 995 7.2. A Stateful Solution to MTU Handling 997 An ITR stateful solution to handle MTU issues is described as 998 follows: 1000 1. The ITR will keep state of the effective MTU for each Locator per 1001 Map-Cache entry. The effective MTU is what the core network can 1002 deliver along the path between the ITR and ETR. 1004 2. When an IPv4-encapsulated packet with the DF bit set to 1, 1005 exceeds what the core network can deliver, one of the 1006 intermediate routers on the path will send an an ICMPv4 1007 Unreachable/Fragmentation-Needed to the ITR, respectively. The 1008 ITR will parse the ICMP message to determine which Locator is 1009 affected by the effective MTU change and then record the new 1010 effective MTU value in the Map-Cache entry. 1012 3. When a packet is received by the ITR from a source inside of the 1013 site and the size of the packet is greater than the effective MTU 1014 stored with the Map-Cache entry associated with the destination 1015 EID the packet is for, the ITR will send an ICMPv4 ICMP 1016 Unreachable/Fragmentation-Needed message back to the source. The 1017 packet size advertised by the ITR in the ICMP message is the 1018 effective MTU minus the LISP encapsulation length. 1020 Even though this mechanism is stateful, it has advantages over the 1021 stateless IP fragmentation mechanism, by not involving the 1022 destination host with reassembly of ITR fragmented packets. 1024 Please note that [RFC1191] and [RFC1981], which describe the use of 1025 ICMP packets for PMTU discovery, can behave suboptimally in the 1026 presence of ICMP black holes or off-path attackers that spoof ICMP. 1027 Possible mitigations include ITRs and ETRs cooperating on MTU probe 1028 packets ([RFC4821], [I-D.ietf-tsvwg-datagram-plpmtud]), or ITRs 1029 storing the beginning of large packets to verify that they match the 1030 echoed packet in ICMP Frag Needed/PTB. 1032 8. Using Virtualization and Segmentation with LISP 1034 There are several cases where segregation is needed at the EID level. 1035 For instance, this is the case for deployments containing overlapping 1036 addresses, traffic isolation policies or multi-tenant virtualization. 1037 For these and other scenarios where segregation is needed, Instance 1038 IDs are used. 1040 An Instance ID can be carried in a LISP-encapsulated packet. An ITR 1041 that prepends a LISP header will copy a 24-bit value used by the LISP 1042 router to uniquely identify the address space. The value is copied 1043 to the 'Instance ID' field of the LISP header, and the I-bit is set 1044 to 1. 1046 When an ETR decapsulates a packet, the Instance ID from the LISP 1047 header is used as a table identifier to locate the forwarding table 1048 to use for the inner destination EID lookup. 1050 For example, an 802.1Q VLAN tag or VPN identifier could be used as a 1051 24-bit Instance ID. See [I-D.ietf-lisp-vpn] for LISP VPN use-case 1052 details. Please note that the Instance ID is not protected, an on- 1053 path attacker can modify the tags and for instance, allow 1054 communicatons between logically isolated VLANs. 1056 Participants within a LISP deployment must agree on the meaning of 1057 Instance ID values. The source and destination EIDs MUST belong to 1058 the same Instance ID. 1060 Instance ID SHOULD NOT be used with overlapping IPv6 EID addresses. 1062 9. Routing Locator Selection 1064 The Map-Cache contains the state used by ITRs and PITRs to 1065 encapsulate packets. When an ITR/PITR receives a packet from inside 1066 the LISP site to a destination outside of the site a longest-prefix 1067 match lookup of the EID is done to the Map-Cache (see Section 6). 1068 The lookup returns a single Locator-Set containing a list of RLOCs 1069 corresponding to the EID's topological location. Each RLOC in the 1070 Locator-Set is associated with a 'Priority' and 'Weight', this 1071 information is used to select the RLOC to encapsulate. 1073 The RLOC with the lowest 'Priority' is selected. An RLOC with 1074 'Priority' 255 means that MUST NOT be used for forwarding. When 1075 multiple RLOCs have the same 'Priority' then the 'Weight' states how 1076 to load balance traffic among them. The value of the 'Weight' 1077 represents the relative weight of the total packets that match the 1078 mapping entry. 1080 The following are different scenarios for choosing RLOCs and the 1081 controls that are available: 1083 o The server-side returns one RLOC. The client-side can only use 1084 one RLOC. The server-side has complete control of the selection. 1086 o The server-side returns a list of RLOCs where a subset of the list 1087 has the same best Priority. The client can only use the subset 1088 list according to the weighting assigned by the server-side. In 1089 this case, the server-side controls both the subset list and load- 1090 splitting across its members. The client-side can use RLOCs 1091 outside of the subset list if it determines that the subset list 1092 is unreachable (unless RLOCs are set to a Priority of 255). Some 1093 sharing of control exists: the server-side determines the 1094 destination RLOC list and load distribution while the client-side 1095 has the option of using alternatives to this list if RLOCs in the 1096 list are unreachable. 1098 o The server-side sets a Weight of zero for the RLOC subset list. 1099 In this case, the client-side can choose how the traffic load is 1100 spread across the subset list. See Section 12 for details on 1101 load-sharing mechanisms. Control is shared by the server-side 1102 determining the list and the client-side determining load 1103 distribution. Again, the client can use alternative RLOCs if the 1104 server-provided list of RLOCs is unreachable. 1106 o Either side (more likely the server-side ETR) decides to "glean" 1107 the RLOCs. For example, if the server-side ETR gleans RLOCs, then 1108 the client-side ITR gives the client-side ITR responsibility for 1109 bidirectional RLOC reachability and preferability. Server-side 1110 ETR gleaning of the client-side ITR RLOC is done by caching the 1111 inner-header source EID and the outer-header source RLOC of 1112 received packets. The client-side ITR controls how traffic is 1113 returned and can alternate using an outer-header source RLOC, 1114 which then can be added to the list the server-side ETR uses to 1115 return traffic. Since no Priority or Weights are provided using 1116 this method, the server-side ETR MUST assume that each client-side 1117 ITR RLOC uses the same best Priority with a Weight of zero. In 1118 addition, since EID-Prefix encoding cannot be conveyed in data 1119 packets, the EID-to-RLOC Cache on Tunnel Routers can grow to be 1120 very large. Gleaning has several important considerations. A 1121 "gleaned" Map-Cache entry is only stored and used for a 1122 RECOMMENDED period of 3 seconds, pending verification. 1123 Verification MUST be performed by sending a Map-Request to the 1124 source EID (the inner-header IP source address) of the received 1125 encapsulated packet. A reply to this "verifying Map-Request" is 1126 used to fully populate the Map-Cache entry for the "gleaned" EID 1127 and is stored and used for the time indicated from the 'TTL' field 1128 of a received Map-Reply. When a verified Map- Cache entry is 1129 stored, data gleaning no longer occurs for subsequent packets that 1130 have a source EID that matches the EID-Prefix of the verified 1131 entry. This "gleaning" mechanism MUST NOT be used over the public 1132 Internet and SHOULD only be used in trusted and closed 1133 deployments. Refer to Section 16 for security issues regarding 1134 this mechanism. 1136 RLOCs that appear in EID-to-RLOC Map-Reply messages are assumed to be 1137 reachable when the R-bit [I-D.ietf-lisp-rfc6833bis] for the Locator 1138 record is set to 1. When the R-bit is set to 0, an ITR or PITR MUST 1139 NOT encapsulate to the RLOC. Neither the information contained in a 1140 Map-Reply nor that stored in the mapping database system provides 1141 reachability information for RLOCs. Note that reachability is not 1142 part of the mapping system and is determined using one or more of the 1143 Routing Locator reachability algorithms described in the next 1144 section. 1146 10. Routing Locator Reachability 1148 Several Data-Plane mechanisms for determining RLOC reachability are 1149 currently defined. Please note that additional Control-Plane based 1150 reachability mechanisms are defined in [I-D.ietf-lisp-rfc6833bis]. 1152 1. An ETR MAY examine the Locator-Status-Bits in the LISP header of 1153 an encapsulated data packet received from an ITR. If the ETR is 1154 also acting as an ITR and has traffic to return to the original 1155 ITR site, it can use this status information to help select an 1156 RLOC. 1158 2. When an ETR receives an encapsulated packet from an ITR, the 1159 source RLOC from the outer header of the packet is likely to be 1160 reachable. Please note that in some scenarios the RLOC from the 1161 outer header can be an spoofable field. 1163 3. An ITR/ETR pair can use the 'Echo-Noncing' Locator reachability 1164 algorithms described in this section. 1166 When determining Locator up/down reachability by examining the 1167 Locator-Status-Bits from the LISP-encapsulated data packet, an ETR 1168 will receive up-to-date status from an encapsulating ITR about 1169 reachability for all ETRs at the site. CE-based ITRs at the source 1170 site can determine reachability relative to each other using the site 1171 IGP as follows: 1173 o Under normal circumstances, each ITR will advertise a default 1174 route into the site IGP. 1176 o If an ITR fails or if the upstream link to its PE fails, its 1177 default route will either time out or be withdrawn. 1179 Each ITR can thus observe the presence or lack of a default route 1180 originated by the others to determine the Locator-Status-Bits it sets 1181 for them. 1183 When ITRs at the site are not deployed in CE routers, the IGP can 1184 still be used to determine the reachability of Locators, provided 1185 they are injected into the IGP. This is typically done when a /32 1186 address is configured on a loopback interface. 1188 RLOCs listed in a Map-Reply are numbered with ordinals 0 to n-1. The 1189 Locator-Status-Bits in a LISP-encapsulated packet are numbered from 0 1190 to n-1 starting with the least significant bit. For example, if an 1191 RLOC listed in the 3rd position of the Map-Reply goes down (ordinal 1192 value 2), then all ITRs at the site will clear the 3rd least 1193 significant bit (xxxx x0xx) of the 'Locator-Status-Bits' field for 1194 the packets they encapsulate. 1196 When an xTR decides to use 'Locator-Status-Bits' to affect 1197 reachability information, it acts as follows: ETRs decapsulating a 1198 packet will check for any change in the 'Locator-Status-Bits' field. 1199 When a bit goes from 1 to 0, the ETR, if acting also as an ITR, will 1200 refrain from encapsulating packets to an RLOC that is indicated as 1201 down. It will only resume using that RLOC if the corresponding 1202 Locator-Status-Bit returns to a value of 1. Locator-Status-Bits are 1203 associated with a Locator-Set per EID-Prefix. Therefore, when a 1204 Locator becomes unreachable, the Locator-Status-Bit that corresponds 1205 to that Locator's position in the list returned by the last Map-Reply 1206 will be set to zero for that particular EID-Prefix. 1208 Locator-Status-Bits MUST NOT be used over the public Internet and 1209 SHOULD only be used in trusted and closed deployments. In addition 1210 Locator-Status-Bits SHOULD be coupled with Map-Versioning 1211 (Section 13.2) to prevent race conditions where Locator-Status-Bits 1212 are interpreted as referring to different RLOCs than intended. Refer 1213 to Section 16 for security issues regarding this mechanism. 1215 If an ITR encapsulates a packet to an ETR and the packet is received 1216 and decapsulated by the ETR, it is implied but not confirmed by the 1217 ITR that the ETR's RLOC is reachable. In most cases, the ETR can 1218 also reach the ITR but cannot assume this to be true, due to the 1219 possibility of path asymmetry. In the presence of unidirectional 1220 traffic flow from an ITR to an ETR, the ITR SHOULD NOT use the lack 1221 of return traffic as an indication that the ETR is unreachable. 1222 Instead, it MUST use an alternate mechanism to determine 1223 reachability. 1225 The security considerations of Section 16 related to data-plane 1226 reachability applies to the data-plane RLOC reachability mechanisms 1227 described in this section. 1229 10.1. Echo Nonce Algorithm 1231 When data flows bidirectionally between Locators from different 1232 sites, a Data-Plane mechanism called "nonce echoing" can be used to 1233 determine reachability between an ITR and ETR. When an ITR wants to 1234 solicit a nonce echo, it sets the N- and E-bits and places a 24-bit 1235 nonce [RFC4086] in the LISP header of the next encapsulated data 1236 packet. 1238 When this packet is received by the ETR, the encapsulated packet is 1239 forwarded as normal. When the ETR is an xTR (co-located as an ITR), 1240 it then sends a data packet to the ITR (when it is an xTR co-located 1241 as an ETR), it includes the nonce received earlier with the N-bit set 1242 and E-bit cleared. The ITR sees this "echoed nonce" and knows that 1243 the path to and from the ETR is up. 1245 The ITR will set the E-bit and N-bit for every packet it sends while 1246 in the echo-nonce-request state. The time the ITR waits to process 1247 the echoed nonce before it determines the path is unreachable is 1248 variable and is a choice left for the implementation. 1250 If the ITR is receiving packets from the ETR but does not see the 1251 nonce echoed while being in the echo-nonce-request state, then the 1252 path to the ETR is unreachable. This decision MAY be overridden by 1253 other Locator reachability algorithms. Once the ITR determines that 1254 the path to the ETR is down, it can switch to another Locator for 1255 that EID-Prefix. 1257 Note that "ITR" and "ETR" are relative terms here. Both devices MUST 1258 be implementing both ITR and ETR functionality for the echo nonce 1259 mechanism to operate. 1261 The ITR and ETR MAY both go into the echo-nonce-request state at the 1262 same time. The number of packets sent or the time during which echo 1263 nonce requests are sent is an implementation-specific setting. In 1264 this case, an xTR receiving the echo-nonce-request packets will 1265 suspend the echo-nonce-request state and setup a 'echo-nonce-request- 1266 state' timer. After the 'echo-nonce-request-state' timer expires it 1267 will resume the echo-nonce-request state. 1269 This mechanism does not completely solve the forward path 1270 reachability problem, as traffic may be unidirectional. That is, the 1271 ETR receiving traffic at a site MAY not be the same device as an ITR 1272 that transmits traffic from that site, or the site-to-site traffic is 1273 unidirectional so there is no ITR returning traffic. 1275 The echo-nonce algorithm is bilateral. That is, if one side sets the 1276 E-bit and the other side is not enabled for echo-noncing, then the 1277 echoing of the nonce does not occur and the requesting side may 1278 erroneously consider the Locator unreachable. An ITR SHOULD set the 1279 E-bit in an encapsulated data packet when it knows the ETR is enabled 1280 for echo-noncing. This is conveyed by the E-bit in the Map-Reply 1281 message. 1283 Many implementations default to not advertising they are echo-nonce 1284 capable in Map-Reply messages and so RLOC-probing tends to be used 1285 for RLOC reachability. 1287 The echo-nonce mechanism MUST NOT be used over the public Internet 1288 and MUST only be used in trusted and closed deployments. Refer to 1289 Section 16 for security issues regarding this mechanism. 1291 11. EID Reachability within a LISP Site 1293 A site MAY be multihomed using two or more ETRs. The hosts and 1294 infrastructure within a site will be addressed using one or more EID- 1295 Prefixes that are mapped to the RLOCs of the relevant ETRs in the 1296 mapping system. One possible failure mode is for an ETR to lose 1297 reachability to one or more of the EID-Prefixes within its own site. 1298 When this occurs when the ETR sends Map-Replies, it can clear the 1299 R-bit associated with its own Locator. And when the ETR is also an 1300 ITR, it can clear its Locator-Status-Bit in the encapsulation data 1301 header. 1303 It is recognized that there are no simple solutions to the site 1304 partitioning problem because it is hard to know which part of the 1305 EID-Prefix range is partitioned and which Locators can reach any sub- 1306 ranges of the EID-Prefixes. Note that this is not a new problem 1307 introduced by the LISP architecture. The problem exists today when a 1308 multihomed site uses BGP to advertise its reachability upstream. 1310 12. Routing Locator Hashing 1312 When an ETR provides an EID-to-RLOC mapping in a Map-Reply message 1313 that is stored in the Map-Cache of a requesting ITR, the Locator-Set 1314 for the EID-Prefix MAY contain different Priority and Weight values 1315 for each locator address. When more than one best Priority Locator 1316 exists, the ITR can decide how to load-share traffic against the 1317 corresponding Locators. 1319 The following hash algorithm MAY be used by an ITR to select a 1320 Locator for a packet destined to an EID for the EID-to-RLOC mapping: 1322 1. Either a source and destination address hash or the traditional 1323 5-tuple hash can be used. The traditional 5-tuple hash includes 1324 the source and destination addresses; source and destination TCP, 1325 UDP, or Stream Control Transmission Protocol (SCTP) port numbers; 1326 and the IP protocol number field or IPv6 next-protocol fields of 1327 a packet that a host originates from within a LISP site. When a 1328 packet is not a TCP, UDP, or SCTP packet, the source and 1329 destination addresses only from the header are used to compute 1330 the hash. 1332 2. Take the hash value and divide it by the number of Locators 1333 stored in the Locator-Set for the EID-to-RLOC mapping. 1335 3. The remainder will yield a value of 0 to "number of Locators 1336 minus 1". Use the remainder to select the Locator in the 1337 Locator-Set. 1339 The specific hash algorithm the ITR uses for load-sharing is out of 1340 scope for this document and does not prevent interoperability. 1342 The Source port SHOULD be the same for all packets belonging to the 1343 same flow. Also note that when a packet is LISP encapsulated, the 1344 source port number in the outer UDP header needs to be set. 1345 Selecting a hashed value allows core routers that are attached to 1346 Link Aggregation Groups (LAGs) to load-split the encapsulated packets 1347 across member links of such LAGs. Otherwise, core routers would see 1348 a single flow, since packets have a source address of the ITR, for 1349 packets that are originated by different EIDs at the source site. A 1350 suggested setting for the source port number computed by an ITR is a 1351 5-tuple hash function on the inner header, as described above. The 1352 source port SHOULD be the same for all packets belonging to the same 1353 flow. 1355 Many core router implementations use a 5-tuple hash to decide how to 1356 balance packet load across members of a LAG. The 5-tuple hash 1357 includes the source and destination addresses of the packet and the 1358 source and destination ports when the protocol number in the packet 1359 is TCP or UDP. For this reason, UDP encoding is used for LISP 1360 encapsulation. In this scenario, when the outer header is IPv6, the 1361 flow label MAY also be set following the procedures specified in 1362 [RFC6438]. When the inner header is IPv6 then the flow label is not 1363 zero, it MAY be used to compute the hash. 1365 13. Changing the Contents of EID-to-RLOC Mappings 1367 Since the LISP architecture uses a caching scheme to retrieve and 1368 store EID-to-RLOC mappings, the only way an ITR can get a more up-to- 1369 date mapping is to re-request the mapping. However, the ITRs do not 1370 know when the mappings change, and the ETRs do not keep track of 1371 which ITRs requested its mappings. For scalability reasons, it is 1372 desirable to maintain this approach but need to provide a way for 1373 ETRs to change their mappings and inform the sites that are currently 1374 communicating with the ETR site using such mappings. 1376 This section defines two Data-Plane mechanism for updating EID-to- 1377 RLOC mappings. Additionally, the Solicit-Map Request (SMR) Control- 1378 Plane updating mechanism is specified in [I-D.ietf-lisp-rfc6833bis]. 1380 13.1. Locator-Status-Bits 1382 Locator-Status-Bits (LSB) can also be used to keep track of the 1383 Locator status (up or down) when EID-to-RLOC mappings are changing. 1384 When LSB are used in a LISP deployment, all LISP tunnel routers MUST 1385 implement both ITR and ETR capabilities (therefore all tunnel routers 1386 are effectively xTRs). In this section the term "source xTR" is used 1387 to refer to the xTR setting the LSB and "destination xTR" is used to 1388 refer to the xTR receiving the LSB. The procedure is as follows: 1390 First, when a Locator record is added or removed from the Locator- 1391 Set, the source xTR will signal this by sending a Solicit-Map Request 1392 (SMR) Control-Plane message [I-D.ietf-lisp-rfc6833bis] to the 1393 destination xTR. At this point the source xTR MUST NOT use LSB 1394 (L-bit = 0) since the destination xTR site has outdated information. 1395 The source xTR will setup a 'use-LSB' timer. 1397 Second and as defined in [I-D.ietf-lisp-rfc6833bis], upon reception 1398 of the SMR message the destination xTR will retrieve the updated EID- 1399 to-RLOC mappings by sending a Map-Request. 1401 And third, when the 'use-LSB' timer expires, the source xTR can use 1402 again LSB with the destination xTR to signal the Locator status (up 1403 or down). The specific value for the 'use-LSB' timer depends on the 1404 LISP deployment, the 'use-LSB' timer needs to be large enough for the 1405 destination xTR to retreive the updated EID-to-RLOC mappings. A 1406 RECOMMENDED value for the 'use-LSB' timer is 5 minutes. 1408 13.2. Database Map-Versioning 1410 When there is unidirectional packet flow between an ITR and ETR, and 1411 the EID-to-RLOC mappings change on the ETR, it needs to inform the 1412 ITR so encapsulation to a removed Locator can stop and can instead be 1413 started to a new Locator in the Locator-Set. 1415 An ETR, when it sends Map-Reply messages, conveys its own Map-Version 1416 Number. This is known as the Destination Map-Version Number. ITRs 1417 include the Destination Map-Version Number in packets they 1418 encapsulate to the site. When an ETR decapsulates a packet and 1419 detects that the Destination Map-Version Number is less than the 1420 current version for its mapping, the SMR procedure described in 1421 [I-D.ietf-lisp-rfc6833bis] occurs. 1423 An ITR, when it encapsulates packets to ETRs, can convey its own Map- 1424 Version Number. This is known as the Source Map-Version Number. 1425 When an ETR decapsulates a packet and detects that the Source Map- 1426 Version Number is greater than the last Map-Version Number sent in a 1427 Map-Reply from the ITR's site, the ETR will send a Map-Request to one 1428 of the ETRs for the source site. 1430 A Map-Version Number is used as a sequence number per EID-Prefix, so 1431 values that are greater are considered to be more recent. A value of 1432 0 for the Source Map-Version Number or the Destination Map-Version 1433 Number conveys no versioning information, and an ITR does no 1434 comparison with previously received Map-Version Numbers. 1436 A Map-Version Number can be included in Map-Register messages as 1437 well. This is a good way for the Map-Server to assure that all ETRs 1438 for a site registering to it will be synchronized according to Map- 1439 Version Number. 1441 Map-Version requires that ETRs within the LISP site are synchronized 1442 with respect to the Map-Version Number, EID-prefix and the set and 1443 status (up/down) of the RLOCs. The use of Map-Versioning without 1444 proper synchronization may cause traffic disruption. The 1445 synchronization protocol is out-of-the-scope of this document, but 1446 MUST keep ETRs synchronized within a 1 minute window. 1448 Map-Versioning MUST NOT be used over the public Internet and SHOULD 1449 only be used in trusted and closed deployments. Refer to Section 16 1450 for security issues regarding this mechanism. 1452 See [I-D.ietf-lisp-6834bis] for a more detailed analysis and 1453 description of Database Map-Versioning. 1455 14. Multicast Considerations 1457 A multicast group address, as defined in the original Internet 1458 architecture, is an identifier of a grouping of topologically 1459 independent receiver host locations. The address encoding itself 1460 does not determine the location of the receiver(s). The multicast 1461 routing protocol, and the network-based state the protocol creates, 1462 determine where the receivers are located. 1464 In the context of LISP, a multicast group address is both an EID and 1465 a Routing Locator. Therefore, no specific semantic or action needs 1466 to be taken for a destination address, as it would appear in an IP 1467 header. Therefore, a group address that appears in an inner IP 1468 header built by a source host will be used as the destination EID. 1469 The outer IP header (the destination Routing Locator address), 1470 prepended by a LISP router, can use the same group address as the 1471 destination Routing Locator, use a multicast or unicast Routing 1472 Locator obtained from a Mapping System lookup, or use other means to 1473 determine the group address mapping. 1475 With respect to the source Routing Locator address, the ITR prepends 1476 its own IP address as the source address of the outer IP header, just 1477 like it would if the destination EID was a unicast address. This 1478 source Routing Locator address, like any other Routing Locator 1479 address, MUST be routable on the underlay. 1481 There are two approaches for LISP-Multicast, one that uses native 1482 multicast routing in the underlay with no support from the Mapping 1483 System and the other that uses only unicast routing in the underlay 1484 with support from the Mapping System. See [RFC6831] and [RFC8378], 1485 respectively, for details. Details for LISP-Multicast and 1486 interworking with non-LISP sites are described in [RFC6831] and 1487 [RFC6832]. 1489 15. Router Performance Considerations 1491 LISP is designed to be very "hardware-based forwarding friendly". A 1492 few implementation techniques can be used to incrementally implement 1493 LISP: 1495 o When a tunnel-encapsulated packet is received by an ETR, the outer 1496 destination address may not be the address of the router. This 1497 makes it challenging for the control plane to get packets from the 1498 hardware. This may be mitigated by creating special Forwarding 1499 Information Base (FIB) entries for the EID-Prefixes of EIDs served 1500 by the ETR (those for which the router provides an RLOC 1501 translation). These FIB entries are marked with a flag indicating 1502 that Control-Plane processing SHOULD be performed. The forwarding 1503 logic of testing for particular IP protocol number values is not 1504 necessary. There are a few proven cases where no changes to 1505 existing deployed hardware were needed to support the LISP Data- 1506 Plane. 1508 o On an ITR, prepending a new IP header consists of adding more 1509 octets to a MAC rewrite string and prepending the string as part 1510 of the outgoing encapsulation procedure. Routers that support 1511 Generic Routing Encapsulation (GRE) tunneling [RFC2784] or 6to4 1512 tunneling [RFC3056] may already support this action. 1514 o A packet's source address or interface the packet was received on 1515 can be used to select VRF (Virtual Routing/Forwarding). The VRF's 1516 routing table can be used to find EID-to-RLOC mappings. 1518 For performance issues related to Map-Cache management, see 1519 Section 16. 1521 16. Security Considerations 1523 In what follows we highlight security considerations that apply when 1524 LISP is deployed in environments such as those specified in 1525 Section 1.1. 1527 The optional mechanisms of gleaning is offered to directly obtain a 1528 mapping from the LISP encapsulated packets. Specifically, an xTR can 1529 learn the EID-to-RLOC mapping by inspecting the source RLOC and 1530 source EID of an encapsulated packet, and insert this new mapping 1531 into its Map-Cache. An off-path attacker can spoof the source EID 1532 address to divert the traffic sent to the victim's spoofed EID. If 1533 the attacker spoofs the source RLOC, it can mount a DoS attack by 1534 redirecting traffic to the spoofed victim's RLOC, potentially 1535 overloading it. 1537 The LISP Data-Plane defines several mechanisms to monitor RLOC Data- 1538 Plane reachability, in this context Locator-Status Bits, Nonce- 1539 Present and Echo-Nonce bits of the LISP encapsulation header can be 1540 manipulated by an attacker to mount a DoS attack. An off-path 1541 attacker able to spoof the RLOC and/or nonce of a victim's xTR can 1542 manipulate such mechanisms to declare false information about the 1543 RLOC's reachability status. 1545 For example of such attacks, an off-path attacker can exploit the 1546 echo-nonce mechanism by sending data packets to an ITR with a random 1547 nonce from an ETR's spoofed RLOC. Note the attacker must guess a 1548 valid nonce the ITR is requesting to be echoed within a small window 1549 of time. The goal is to convince the ITR that the ETR's RLOC is 1550 reachable even when it may not be reachable. If the attack is 1551 successful, the ITR believes the wrong reachability status of the 1552 ETR's RLOC until RLOC-probing detects the correct status. This time 1553 frame is on the order of 10s of seconds. This specific attack can be 1554 mitigated by preventing RLOC spoofing in the network by deploying 1555 uRPF BCP 38 [RFC2827]. In addition and in order to exploit this 1556 vulnerability, the off-path attacker must send echo-nonce packets at 1557 high rate. If the nonces have never been requested by the ITR, it 1558 can protect itself from erroneous reachability attacks. 1560 A LISP-specific uRPF check is also possible. When decapsulating, an 1561 ETR can check that the source EID and RLOC are valid EID-to-RLOC 1562 mappings by checking the Mapping System. 1564 Map-Versioning is a Data-Plane mechanism used to signal a peering xTR 1565 that a local EID-to-RLOC mapping has been updated, so that the 1566 peering xTR uses LISP Control-Plane signaling message to retrieve a 1567 fresh mapping. This can be used by an attacker to forge the map- 1568 versioning field of a LISP encapsulated header and force an excessive 1569 amount of signaling between xTRs that may overload them. 1571 Locator-Status-Bits, echo-nonce and map-versioning MUST NOT be used 1572 over the public Internet and SHOULD only be used in trusted and 1573 closed deployments. In addition Locator-Status-Bits SHOULD be 1574 coupled with map-versioning to prevent race conditions where Locator- 1575 Status-Bits are interpreted as referring to different RLOCs than 1576 intended. 1578 LISP implementations and deployments which permit outer header 1579 fragments of IPv6 LISP encapsulated packets as a means of dealing 1580 with MTU issues should also use implementation techniques in ETRs to 1581 prevent this from being a DoS attack vector. Limits on the number of 1582 fragments awaiting reassembly at an ETR, RTR, or PETR, and the rate 1583 of admitting such fragments may be used. 1585 17. Network Management Considerations 1587 Considerations for network management tools exist so the LISP 1588 protocol suite can be operationally managed. These mechanisms can be 1589 found in [RFC7052] and [RFC6835]. 1591 18. Changes since RFC 6830 1593 For implementation considerations, the following changes have been 1594 made to this document since RFC 6830 was published: 1596 o It is no longer mandated that a maximum number of 2 LISP headers 1597 be prepended to a packet. If there is a application need for more 1598 than 2 LISP headers, an implementation can support more. However, 1599 it is RECOMMENDED that a maximum of two LISP headers can be 1600 prepended to a packet. 1602 o The 3 reserved flag bits in the LISP header have been allocated 1603 for [RFC8061]. The low-order 2 bits of the 3-bit field (now named 1604 the KK bits) are used as a key identifier. The 1 remaining bit is 1605 still documented as reserved and unassigned. 1607 o Data-Plane gleaning for creating map-cache entries has been made 1608 optional. Any ITR implementations that depend on or assume the 1609 remote ETR is gleaning should not do so. This does not create any 1610 interoperability problems since the control-plane map-cache 1611 population procedures are unilateral and are the typical method 1612 for map-cache population. 1614 o The bulk of the changes to this document which reduces its length 1615 are due to moving the LISP control-plane messaging and procedures 1616 to [I-D.ietf-lisp-rfc6833bis]. 1618 19. IANA Considerations 1620 This section provides guidance to the Internet Assigned Numbers 1621 Authority (IANA) regarding registration of values related to this 1622 Data-Plane LISP specification, in accordance with BCP 26 [RFC8126]. 1624 19.1. LISP UDP Port Numbers 1626 The IANA registry has allocated UDP port number 4341 for the LISP 1627 Data-Plane. IANA has updated the description for UDP port 4341 as 1628 follows: 1630 lisp-data 4341 udp LISP Data Packets 1632 20. References 1634 20.1. Normative References 1636 [I-D.ietf-lisp-6834bis] 1637 Iannone, L., Saucez, D., and O. Bonaventure, "Locator/ID 1638 Separation Protocol (LISP) Map-Versioning", draft-ietf- 1639 lisp-6834bis-07 (work in progress), October 2020. 1641 [I-D.ietf-lisp-rfc6833bis] 1642 Farinacci, D., Maino, F., Fuller, V., and A. Cabellos- 1643 Aparicio, "Locator/ID Separation Protocol (LISP) Control- 1644 Plane", draft-ietf-lisp-rfc6833bis-29 (work in progress), 1645 September 2020. 1647 [RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768, 1648 DOI 10.17487/RFC0768, August 1980, 1649 . 1651 [RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, 1652 DOI 10.17487/RFC0791, September 1981, 1653 . 1655 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1656 Requirement Levels", BCP 14, RFC 2119, 1657 DOI 10.17487/RFC2119, March 1997, 1658 . 1660 [RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, 1661 "Definition of the Differentiated Services Field (DS 1662 Field) in the IPv4 and IPv6 Headers", RFC 2474, 1663 DOI 10.17487/RFC2474, December 1998, 1664 . 1666 [RFC2827] Ferguson, P. and D. Senie, "Network Ingress Filtering: 1667 Defeating Denial of Service Attacks which employ IP Source 1668 Address Spoofing", BCP 38, RFC 2827, DOI 10.17487/RFC2827, 1669 May 2000, . 1671 [RFC2983] Black, D., "Differentiated Services and Tunnels", 1672 RFC 2983, DOI 10.17487/RFC2983, October 2000, 1673 . 1675 [RFC6040] Briscoe, B., "Tunnelling of Explicit Congestion 1676 Notification", RFC 6040, DOI 10.17487/RFC6040, November 1677 2010, . 1679 [RFC6438] Carpenter, B. and S. Amante, "Using the IPv6 Flow Label 1680 for Equal Cost Multipath Routing and Link Aggregation in 1681 Tunnels", RFC 6438, DOI 10.17487/RFC6438, November 2011, 1682 . 1684 [RFC6830] Farinacci, D., Fuller, V., Meyer, D., and D. Lewis, "The 1685 Locator/ID Separation Protocol (LISP)", RFC 6830, 1686 DOI 10.17487/RFC6830, January 2013, 1687 . 1689 [RFC6831] Farinacci, D., Meyer, D., Zwiebel, J., and S. Venaas, "The 1690 Locator/ID Separation Protocol (LISP) for Multicast 1691 Environments", RFC 6831, DOI 10.17487/RFC6831, January 1692 2013, . 1694 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 1695 Writing an IANA Considerations Section in RFCs", BCP 26, 1696 RFC 8126, DOI 10.17487/RFC8126, June 2017, 1697 . 1699 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1700 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1701 May 2017, . 1703 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 1704 (IPv6) Specification", STD 86, RFC 8200, 1705 DOI 10.17487/RFC8200, July 2017, 1706 . 1708 [RFC8378] Moreno, V. and D. Farinacci, "Signal-Free Locator/ID 1709 Separation Protocol (LISP) Multicast", RFC 8378, 1710 DOI 10.17487/RFC8378, May 2018, 1711 . 1713 20.2. Informative References 1715 [AFN] IANA, "Address Family Numbers", August 2016, 1716 . 1718 [CHIAPPA] Chiappa, J., "Endpoints and Endpoint names: A Proposed", 1719 1999, 1720 . 1722 [I-D.ietf-lisp-introduction] 1723 Cabellos-Aparicio, A. and D. Saucez, "An Architectural 1724 Introduction to the Locator/ID Separation Protocol 1725 (LISP)", draft-ietf-lisp-introduction-13 (work in 1726 progress), April 2015. 1728 [I-D.ietf-lisp-vpn] 1729 Moreno, V. and D. Farinacci, "LISP Virtual Private 1730 Networks (VPNs)", draft-ietf-lisp-vpn-06 (work in 1731 progress), August 2020. 1733 [I-D.ietf-tsvwg-datagram-plpmtud] 1734 Fairhurst, G., Jones, T., Tuexen, M., Ruengeler, I., and 1735 T. Voelker, "Packetization Layer Path MTU Discovery for 1736 Datagram Transports", draft-ietf-tsvwg-datagram-plpmtud-22 1737 (work in progress), June 2020. 1739 [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", 1740 STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987, 1741 . 1743 [RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191, 1744 DOI 10.17487/RFC1191, November 1990, 1745 . 1747 [RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G., 1748 and E. Lear, "Address Allocation for Private Internets", 1749 BCP 5, RFC 1918, DOI 10.17487/RFC1918, February 1996, 1750 . 1752 [RFC1981] McCann, J., Deering, S., and J. Mogul, "Path MTU Discovery 1753 for IP version 6", RFC 1981, DOI 10.17487/RFC1981, August 1754 1996, . 1756 [RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P. 1757 Traina, "Generic Routing Encapsulation (GRE)", RFC 2784, 1758 DOI 10.17487/RFC2784, March 2000, 1759 . 1761 [RFC3056] Carpenter, B. and K. Moore, "Connection of IPv6 Domains 1762 via IPv4 Clouds", RFC 3056, DOI 10.17487/RFC3056, February 1763 2001, . 1765 [RFC3232] Reynolds, J., Ed., "Assigned Numbers: RFC 1700 is Replaced 1766 by an On-line Database", RFC 3232, DOI 10.17487/RFC3232, 1767 January 2002, . 1769 [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, 1770 A., Peterson, J., Sparks, R., Handley, M., and E. 1771 Schooler, "SIP: Session Initiation Protocol", RFC 3261, 1772 DOI 10.17487/RFC3261, June 2002, 1773 . 1775 [RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker, 1776 "Randomness Requirements for Security", BCP 106, RFC 4086, 1777 DOI 10.17487/RFC4086, June 2005, 1778 . 1780 [RFC4459] Savola, P., "MTU and Fragmentation Issues with In-the- 1781 Network Tunneling", RFC 4459, DOI 10.17487/RFC4459, April 1782 2006, . 1784 [RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU 1785 Discovery", RFC 4821, DOI 10.17487/RFC4821, March 2007, 1786 . 1788 [RFC4984] Meyer, D., Ed., Zhang, L., Ed., and K. Fall, Ed., "Report 1789 from the IAB Workshop on Routing and Addressing", 1790 RFC 4984, DOI 10.17487/RFC4984, September 2007, 1791 . 1793 [RFC6832] Lewis, D., Meyer, D., Farinacci, D., and V. Fuller, 1794 "Interworking between Locator/ID Separation Protocol 1795 (LISP) and Non-LISP Sites", RFC 6832, 1796 DOI 10.17487/RFC6832, January 2013, 1797 . 1799 [RFC6835] Farinacci, D. and D. Meyer, "The Locator/ID Separation 1800 Protocol Internet Groper (LIG)", RFC 6835, 1801 DOI 10.17487/RFC6835, January 2013, 1802 . 1804 [RFC6935] Eubanks, M., Chimento, P., and M. Westerlund, "IPv6 and 1805 UDP Checksums for Tunneled Packets", RFC 6935, 1806 DOI 10.17487/RFC6935, April 2013, 1807 . 1809 [RFC6936] Fairhurst, G. and M. Westerlund, "Applicability Statement 1810 for the Use of IPv6 UDP Datagrams with Zero Checksums", 1811 RFC 6936, DOI 10.17487/RFC6936, April 2013, 1812 . 1814 [RFC7052] Schudel, G., Jain, A., and V. Moreno, "Locator/ID 1815 Separation Protocol (LISP) MIB", RFC 7052, 1816 DOI 10.17487/RFC7052, October 2013, 1817 . 1819 [RFC7215] Jakab, L., Cabellos-Aparicio, A., Coras, F., Domingo- 1820 Pascual, J., and D. Lewis, "Locator/Identifier Separation 1821 Protocol (LISP) Network Element Deployment 1822 Considerations", RFC 7215, DOI 10.17487/RFC7215, April 1823 2014, . 1825 [RFC8060] Farinacci, D., Meyer, D., and J. Snijders, "LISP Canonical 1826 Address Format (LCAF)", RFC 8060, DOI 10.17487/RFC8060, 1827 February 2017, . 1829 [RFC8061] Farinacci, D. and B. Weis, "Locator/ID Separation Protocol 1830 (LISP) Data-Plane Confidentiality", RFC 8061, 1831 DOI 10.17487/RFC8061, February 2017, 1832 . 1834 [RFC8085] Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage 1835 Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085, 1836 March 2017, . 1838 Appendix A. Acknowledgments 1840 An initial thank you goes to Dave Oran for planting the seeds for the 1841 initial ideas for LISP. His consultation continues to provide value 1842 to the LISP authors. 1844 A special and appreciative thank you goes to Noel Chiappa for 1845 providing architectural impetus over the past decades on separation 1846 of location and identity, as well as detailed reviews of the LISP 1847 architecture and documents, coupled with enthusiasm for making LISP a 1848 practical and incremental transition for the Internet. 1850 The original authors would like to gratefully acknowledge many people 1851 who have contributed discussions and ideas to the making of this 1852 proposal. They include Scott Brim, Andrew Partan, John Zwiebel, 1853 Jason Schiller, Lixia Zhang, Dorian Kim, Peter Schoenmaker, Vijay 1854 Gill, Geoff Huston, David Conrad, Mark Handley, Ron Bonica, Ted 1855 Seely, Mark Townsley, Chris Morrow, Brian Weis, Dave McGrew, Peter 1856 Lothberg, Dave Thaler, Eliot Lear, Shane Amante, Ved Kafle, Olivier 1857 Bonaventure, Luigi Iannone, Robin Whittle, Brian Carpenter, Joel 1858 Halpern, Terry Manderson, Roger Jorgensen, Ran Atkinson, Stig Venaas, 1859 Iljitsch van Beijnum, Roland Bless, Dana Blair, Bill Lynch, Marc 1860 Woolward, Damien Saucez, Damian Lezama, Attilla De Groot, Parantap 1861 Lahiri, David Black, Roque Gagliano, Isidor Kouvelas, Jesper Skriver, 1862 Fred Templin, Margaret Wasserman, Sam Hartman, Michael Hofling, Pedro 1863 Marques, Jari Arkko, Gregg Schudel, Srinivas Subramanian, Amit Jain, 1864 Xu Xiaohu, Dhirendra Trivedi, Yakov Rekhter, John Scudder, John 1865 Drake, Dimitri Papadimitriou, Ross Callon, Selina Heimlich, Job 1866 Snijders, Vina Ermagan, Fabio Maino, Victor Moreno, Chris White, 1867 Clarence Filsfils, Alia Atlas, Florin Coras and Alberto Rodriguez. 1869 This work originated in the Routing Research Group (RRG) of the IRTF. 1870 An individual submission was converted into the IETF LISP working 1871 group document that became this RFC. 1873 The LISP working group would like to give a special thanks to Jari 1874 Arkko, the Internet Area AD at the time that the set of LISP 1875 documents were being prepared for IESG last call, and for his 1876 meticulous reviews and detailed commentaries on the 7 working group 1877 last call documents progressing toward standards-track RFCs. 1879 The current authors would like to give a sincere thank you to the 1880 people who help put LISP on standards track in the IETF. They 1881 include Joel Halpern, Luigi Iannone, Deborah Brungard, Fabio Maino, 1882 Scott Bradner, Kyle Rose, Takeshi Takahashi, Sarah Banks, Pete 1883 Resnick, Colin Perkins, Mirja Kuhlewind, Francis Dupont, Benjamin 1884 Kaduk, Eric Rescorla, Alvaro Retana, Alexey Melnikov, Alissa Cooper, 1885 Suresh Krishnan, Alberto Rodriguez-Natal, Vina Ermagen, Mohamed 1886 Boucadair, Brian Trammell, Sabrina Tanamal, and John Drake. The 1887 contributions they offered greatly added to the security, scale, and 1888 robustness of the LISP architecture and protocols. 1890 Appendix B. Document Change Log 1892 [RFC Editor: Please delete this section on publication as RFC.] 1894 B.1. Changes to draft-ietf-lisp-rfc6830bis-27 1896 o Posted November 2019. 1898 o Fixed how LSB behave in the presence of new/removed locators. 1900 o Added ETR synchronization requirements when using Map-Versioning. 1902 o Fixed a large set of minor comments and edits. 1904 B.2. Changes to draft-ietf-lisp-rfc6830bis-27 1906 o Posted April 2019 post telechat. 1908 o Made editorial corrections per Warren's suggestions. 1910 o Put in suggested text from Luigi that Mirja agreed with. 1912 o LSB, Echo-Nonce and Map-Versioning SHOULD be only used in closed 1913 environments. 1915 o Removed paragraph stating that Instance-ID can be 32-bit in the 1916 control-plane. 1918 o 6831/8378 are now normative. 1920 o Rewritten Security Considerations according to the changes. 1922 o Stated that LSB SHOULD be coupled with Map-Versioning. 1924 B.3. Changes to draft-ietf-lisp-rfc6830bis-26 1926 o Posted late October 2018. 1928 o Changed description about "reserved" bits to state "reserved and 1929 unassigned". 1931 B.4. Changes to draft-ietf-lisp-rfc6830bis-25 1933 o Posted mid October 2018. 1935 o Added more to the Security Considerations section with discussion 1936 about echo-nonce attacks. 1938 B.5. Changes to draft-ietf-lisp-rfc6830bis-24 1940 o Posted mid October 2018. 1942 o Final editorial changes for Eric and Ben. 1944 B.6. Changes to draft-ietf-lisp-rfc6830bis-23 1946 o Posted early October 2018. 1948 o Added an applicability statement in section 1 to address security 1949 concerns from Telechat. 1951 B.7. Changes to draft-ietf-lisp-rfc6830bis-22 1953 o Posted early October 2018. 1955 o Changes to reflect comments post Telechat. 1957 B.8. Changes to draft-ietf-lisp-rfc6830bis-21 1959 o Posted late-September 2018. 1961 o Changes to reflect comments from Sep 27th Telechat. 1963 B.9. Changes to draft-ietf-lisp-rfc6830bis-20 1965 o Posted late-September 2018. 1967 o Fix old reference to RFC3168, changed to RFC6040. 1969 B.10. Changes to draft-ietf-lisp-rfc6830bis-19 1971 o Posted late-September 2018. 1973 o More editorial changes. 1975 B.11. Changes to draft-ietf-lisp-rfc6830bis-18 1977 o Posted mid-September 2018. 1979 o Changes to reflect comments from Secdir review (Mirja). 1981 B.12. Changes to draft-ietf-lisp-rfc6830bis-17 1983 o Posted September 2018. 1985 o Indicate in the "Changes since RFC 6830" section why the document 1986 has been shortened in length. 1988 o Make reference to RFC 8085 about UDP congestion control. 1990 o More editorial changes from multiple IESG reviews. 1992 B.13. Changes to draft-ietf-lisp-rfc6830bis-16 1994 o Posted late August 2018. 1996 o Distinguish the message type names between ICMP for IPv4 and ICMP 1997 for IPv6 for handling MTU issues. 1999 B.14. Changes to draft-ietf-lisp-rfc6830bis-15 2001 o Posted August 2018. 2003 o Final editorial changes before RFC submission for Proposed 2004 Standard. 2006 o Added section "Changes since RFC 6830" so implementers are 2007 informed of any changes since the last RFC publication. 2009 B.15. Changes to draft-ietf-lisp-rfc6830bis-14 2011 o Posted July 2018 IETF week. 2013 o Put obsolete of RFC 6830 in Intro section in addition to abstract. 2015 B.16. Changes to draft-ietf-lisp-rfc6830bis-13 2017 o Posted March IETF Week 2018. 2019 o Clarified that a new nonce is required per RLOC. 2021 o Removed 'Clock Sweep' section. This text must be placed in a new 2022 OAM document. 2024 o Some references changed from normative to informative 2026 B.17. Changes to draft-ietf-lisp-rfc6830bis-12 2028 o Posted July 2018. 2030 o Fixed Luigi editorial comments to ready draft for RFC status. 2032 B.18. Changes to draft-ietf-lisp-rfc6830bis-11 2034 o Posted March 2018. 2036 o Removed sections 16, 17 and 18 (Mobility, Deployment and 2037 Traceroute considerations). This text must be placed in a new OAM 2038 document. 2040 B.19. Changes to draft-ietf-lisp-rfc6830bis-10 2042 o Posted March 2018. 2044 o Updated section 'Router Locator Selection' stating that the Data- 2045 Plane MUST follow what's stored in the Map-Cache (priorities and 2046 weights). 2048 o Section 'Routing Locator Reachability': Removed bullet point 2 2049 (ICMP Network/Host Unreachable),3 (hints from BGP),4 (ICMP Port 2050 Unreachable),5 (receive a Map-Reply as a response) and RLOC 2051 probing 2053 o Removed 'Solicit-Map Request'. 2055 B.20. Changes to draft-ietf-lisp-rfc6830bis-09 2057 o Posted January 2018. 2059 o Add more details in section 5.3 about DSCP processing during 2060 encapsulation and decapsulation. 2062 o Added clarity to definitions in the Definition of Terms section 2063 from various commenters. 2065 o Removed PA and PI definitions from Definition of Terms section. 2067 o More editorial changes. 2069 o Removed 4342 from IANA section and move to RFC6833 IANA section. 2071 B.21. Changes to draft-ietf-lisp-rfc6830bis-08 2073 o Posted January 2018. 2075 o Remove references to research work for any protocol mechanisms. 2077 o Document scanned to make sure it is RFC 2119 compliant. 2079 o Made changes to reflect comments from document WG shepherd Luigi 2080 Iannone. 2082 o Ran IDNITs on the document. 2084 B.22. Changes to draft-ietf-lisp-rfc6830bis-07 2086 o Posted November 2017. 2088 o Rephrase how Instance-IDs are used and don't refer to [RFC1918] 2089 addresses. 2091 B.23. Changes to draft-ietf-lisp-rfc6830bis-06 2093 o Posted October 2017. 2095 o Put RTR definition before it is used. 2097 o Rename references that are now working group drafts. 2099 o Remove "EIDs MUST NOT be used as used by a host to refer to other 2100 hosts. Note that EID blocks MAY LISP RLOCs". 2102 o Indicate what address-family can appear in data packets. 2104 o ETRs may, rather than will, be the ones to send Map-Replies. 2106 o Recommend, rather than mandate, max encapsulation headers to 2. 2108 o Reference VPN draft when introducing Instance-ID. 2110 o Indicate that SMRs can be sent when ITR/ETR are in the same node. 2112 o Clarify when private addresses can be used. 2114 B.24. Changes to draft-ietf-lisp-rfc6830bis-05 2116 o Posted August 2017. 2118 o Make it clear that a Re-encapsulating Tunnel Router is an RTR. 2120 B.25. Changes to draft-ietf-lisp-rfc6830bis-04 2122 o Posted July 2017. 2124 o Changed reference of IPv6 RFC2460 to RFC8200. 2126 o Indicate that the applicability statement for UDP zero checksums 2127 over IPv6 adheres to RFC6936. 2129 B.26. Changes to draft-ietf-lisp-rfc6830bis-03 2131 o Posted May 2017. 2133 o Move the control-plane related codepoints in the IANA 2134 Considerations section to RFC6833bis. 2136 B.27. Changes to draft-ietf-lisp-rfc6830bis-02 2138 o Posted April 2017. 2140 o Reflect some editorial comments from Damien Sausez. 2142 B.28. Changes to draft-ietf-lisp-rfc6830bis-01 2144 o Posted March 2017. 2146 o Include references to new RFCs published. 2148 o Change references from RFC6833 to RFC6833bis. 2150 o Clarified LCAF text in the IANA section. 2152 o Remove references to "experimental". 2154 B.29. Changes to draft-ietf-lisp-rfc6830bis-00 2156 o Posted December 2016. 2158 o Created working group document from draft-farinacci-lisp 2159 -rfc6830-00 individual submission. No other changes made. 2161 Authors' Addresses 2163 Dino Farinacci 2164 lispers.net 2166 EMail: farinacci@gmail.com 2167 Vince Fuller 2168 vaf.net Internet Consulting 2170 EMail: vince.fuller@gmail.com 2172 Dave Meyer 2173 1-4-5.net 2175 EMail: dmm@1-4-5.net 2177 Darrel Lewis 2178 Cisco Systems 2179 170 Tasman Drive 2180 San Jose, CA 2181 USA 2183 EMail: darlewis@cisco.com 2185 Albert Cabellos 2186 UPC/BarcelonaTech 2187 Campus Nord, C. Jordi Girona 1-3 2188 Barcelona, Catalunya 2189 Spain 2191 EMail: acabello@ac.upc.edu