idnits 2.17.1 draft-ietf-lisp-rfc6830bis-25.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (October 21, 2018) is 2014 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Unused Reference: 'RFC7833' is defined on line 1753, but no explicit reference was found in the text == Outdated reference: A later version (-14) exists of draft-ietf-lisp-6834bis-02 == Outdated reference: A later version (-31) exists of draft-ietf-lisp-rfc6833bis-18 == Outdated reference: A later version (-15) exists of draft-ietf-lisp-introduction-13 == Outdated reference: A later version (-12) exists of draft-ietf-lisp-vpn-02 Summary: 0 errors (**), 0 flaws (~~), 6 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group D. Farinacci 3 Internet-Draft V. Fuller 4 Obsoletes: 6830 (if approved) D. Meyer 5 Intended status: Standards Track D. Lewis 6 Expires: April 24, 2019 Cisco Systems 7 A. Cabellos (Ed.) 8 UPC/BarcelonaTech 9 October 21, 2018 11 The Locator/ID Separation Protocol (LISP) 12 draft-ietf-lisp-rfc6830bis-25 14 Abstract 16 This document describes the Data-Plane protocol for the Locator/ID 17 Separation Protocol (LISP). LISP defines two namespaces, End-point 18 Identifiers (EIDs) that identify end-hosts and Routing Locators 19 (RLOCs) that identify network attachment points. With this, LISP 20 effectively separates control from data, and allows routers to create 21 overlay networks. LISP-capable routers exchange encapsulated packets 22 according to EID-to-RLOC mappings stored in a local Map-Cache. 24 LISP requires no change to either host protocol stacks or to underlay 25 routers and offers Traffic Engineering, multihoming and mobility, 26 among other features. 28 This document obsoletes RFC 6830. 30 Status of This Memo 32 This Internet-Draft is submitted in full conformance with the 33 provisions of BCP 78 and BCP 79. 35 Internet-Drafts are working documents of the Internet Engineering 36 Task Force (IETF). Note that other groups may also distribute 37 working documents as Internet-Drafts. The list of current Internet- 38 Drafts is at https://datatracker.ietf.org/drafts/current/. 40 Internet-Drafts are draft documents valid for a maximum of six months 41 and may be updated, replaced, or obsoleted by other documents at any 42 time. It is inappropriate to use Internet-Drafts as reference 43 material or to cite them other than as "work in progress." 45 This Internet-Draft will expire on April 24, 2019. 47 Copyright Notice 49 Copyright (c) 2018 IETF Trust and the persons identified as the 50 document authors. All rights reserved. 52 This document is subject to BCP 78 and the IETF Trust's Legal 53 Provisions Relating to IETF Documents 54 (https://trustee.ietf.org/license-info) in effect on the date of 55 publication of this document. Please review these documents 56 carefully, as they describe your rights and restrictions with respect 57 to this document. Code Components extracted from this document must 58 include Simplified BSD License text as described in Section 4.e of 59 the Trust Legal Provisions and are provided without warranty as 60 described in the Simplified BSD License. 62 Table of Contents 64 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 65 1.1. Scope of Applicability . . . . . . . . . . . . . . . . . 4 66 2. Requirements Notation . . . . . . . . . . . . . . . . . . . . 4 67 3. Definition of Terms . . . . . . . . . . . . . . . . . . . . . 5 68 4. Basic Overview . . . . . . . . . . . . . . . . . . . . . . . 9 69 4.1. Packet Flow Sequence . . . . . . . . . . . . . . . . . . 11 70 5. LISP Encapsulation Details . . . . . . . . . . . . . . . . . 13 71 5.1. LISP IPv4-in-IPv4 Header Format . . . . . . . . . . . . . 13 72 5.2. LISP IPv6-in-IPv6 Header Format . . . . . . . . . . . . . 14 73 5.3. Tunnel Header Field Descriptions . . . . . . . . . . . . 15 74 6. LISP EID-to-RLOC Map-Cache . . . . . . . . . . . . . . . . . 20 75 7. Dealing with Large Encapsulated Packets . . . . . . . . . . . 20 76 7.1. A Stateless Solution to MTU Handling . . . . . . . . . . 21 77 7.2. A Stateful Solution to MTU Handling . . . . . . . . . . . 22 78 8. Using Virtualization and Segmentation with LISP . . . . . . . 22 79 9. Routing Locator Selection . . . . . . . . . . . . . . . . . . 23 80 10. Routing Locator Reachability . . . . . . . . . . . . . . . . 25 81 10.1. Echo Nonce Algorithm . . . . . . . . . . . . . . . . . . 26 82 11. EID Reachability within a LISP Site . . . . . . . . . . . . . 27 83 12. Routing Locator Hashing . . . . . . . . . . . . . . . . . . . 28 84 13. Changing the Contents of EID-to-RLOC Mappings . . . . . . . . 29 85 13.1. Database Map-Versioning . . . . . . . . . . . . . . . . 30 86 14. Multicast Considerations . . . . . . . . . . . . . . . . . . 31 87 15. Router Performance Considerations . . . . . . . . . . . . . . 31 88 16. Security Considerations . . . . . . . . . . . . . . . . . . . 32 89 17. Network Management Considerations . . . . . . . . . . . . . . 33 90 18. Changes since RFC 6830 . . . . . . . . . . . . . . . . . . . 33 91 19. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 34 92 19.1. LISP UDP Port Numbers . . . . . . . . . . . . . . . . . 34 93 20. References . . . . . . . . . . . . . . . . . . . . . . . . . 34 94 20.1. Normative References . . . . . . . . . . . . . . . . . . 34 95 20.2. Informative References . . . . . . . . . . . . . . . . . 35 96 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 39 97 Appendix B. Document Change Log . . . . . . . . . . . . . . . . 40 98 B.1. Changes to draft-ietf-lisp-rfc6830bis-24 . . . . . . . . 40 99 B.2. Changes to draft-ietf-lisp-rfc6830bis-24 . . . . . . . . 40 100 B.3. Changes to draft-ietf-lisp-rfc6830bis-23 . . . . . . . . 40 101 B.4. Changes to draft-ietf-lisp-rfc6830bis-22 . . . . . . . . 40 102 B.5. Changes to draft-ietf-lisp-rfc6830bis-21 . . . . . . . . 40 103 B.6. Changes to draft-ietf-lisp-rfc6830bis-20 . . . . . . . . 40 104 B.7. Changes to draft-ietf-lisp-rfc6830bis-19 . . . . . . . . 41 105 B.8. Changes to draft-ietf-lisp-rfc6830bis-18 . . . . . . . . 41 106 B.9. Changes to draft-ietf-lisp-rfc6830bis-17 . . . . . . . . 41 107 B.10. Changes to draft-ietf-lisp-rfc6830bis-16 . . . . . . . . 41 108 B.11. Changes to draft-ietf-lisp-rfc6830bis-15 . . . . . . . . 41 109 B.12. Changes to draft-ietf-lisp-rfc6830bis-14 . . . . . . . . 41 110 B.13. Changes to draft-ietf-lisp-rfc6830bis-13 . . . . . . . . 42 111 B.14. Changes to draft-ietf-lisp-rfc6830bis-12 . . . . . . . . 42 112 B.15. Changes to draft-ietf-lisp-rfc6830bis-11 . . . . . . . . 42 113 B.16. Changes to draft-ietf-lisp-rfc6830bis-10 . . . . . . . . 42 114 B.17. Changes to draft-ietf-lisp-rfc6830bis-09 . . . . . . . . 42 115 B.18. Changes to draft-ietf-lisp-rfc6830bis-08 . . . . . . . . 43 116 B.19. Changes to draft-ietf-lisp-rfc6830bis-07 . . . . . . . . 43 117 B.20. Changes to draft-ietf-lisp-rfc6830bis-06 . . . . . . . . 43 118 B.21. Changes to draft-ietf-lisp-rfc6830bis-05 . . . . . . . . 44 119 B.22. Changes to draft-ietf-lisp-rfc6830bis-04 . . . . . . . . 44 120 B.23. Changes to draft-ietf-lisp-rfc6830bis-03 . . . . . . . . 44 121 B.24. Changes to draft-ietf-lisp-rfc6830bis-02 . . . . . . . . 44 122 B.25. Changes to draft-ietf-lisp-rfc6830bis-01 . . . . . . . . 44 123 B.26. Changes to draft-ietf-lisp-rfc6830bis-00 . . . . . . . . 45 124 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 45 126 1. Introduction 128 This document describes the Locator/Identifier Separation Protocol 129 (LISP). LISP is an encapsulation protocol built around the 130 fundamental idea of separating the topological location of a network 131 attachment point from the node's identity [CHIAPPA]. As a result 132 LISP creates two namespaces: Endpoint Identifiers (EIDs), that are 133 used to identify end-hosts (e.g., nodes or Virtual Machines) and 134 routable Routing Locators (RLOCs), used to identify network 135 attachment points. LISP then defines functions for mapping between 136 the two namespaces and for encapsulating traffic originated by 137 devices using non-routable EIDs for transport across a network 138 infrastructure that routes and forwards using RLOCs. LISP 139 encapsulation uses a dynamic form of tunneling where no static 140 provisioning is required or necessary. 142 LISP is an overlay protocol that separates control from Data-Plane, 143 this document specifies the Data-Plane, how LISP-capable routers 144 (Tunnel Routers) exchange packets by encapsulating them to the 145 appropriate location. Tunnel routers are equipped with a cache, 146 called Map-Cache, that contains EID-to-RLOC mappings. The Map-Cache 147 is populated using the LISP Control-Plane protocol 148 [I-D.ietf-lisp-rfc6833bis]. 150 LISP does not require changes to either host protocol stack or to 151 underlay routers. By separating the EID from the RLOC space, LISP 152 offers native Traffic Engineering, multihoming and mobility, among 153 other features. 155 Creation of LISP was initially motivated by discussions during the 156 IAB-sponsored Routing and Addressing Workshop held in Amsterdam in 157 October 2006 (see [RFC4984]). 159 This document specifies the LISP Data-Plane encapsulation and other 160 LISP forwarding node functionality while [I-D.ietf-lisp-rfc6833bis] 161 specifies the LISP control plane. LISP deployment guidelines can be 162 found in [RFC7215] and [RFC6835] describes considerations for network 163 operational management. Finally, [I-D.ietf-lisp-introduction] 164 describes the LISP architecture. 166 This document obsoletes RFC 6830. 168 1.1. Scope of Applicability 170 LISP was originally developed to address the Internet-wide route 171 scaling problem [RFC4984]. While there are a number of approaches of 172 interest for that problem, as LISP as been developed and refined, a 173 large number of other LISP uses have been found and are being used. 174 As such, the design and development of LISP has changed so as to 175 focus on these use cases. The common property of these uses is a 176 large set of cooperating entities seeking to communicate over the 177 public Internet or other large underlay IP infrastructures, while 178 keeping the addressing and topology of the cooperating entities 179 separate from the underlay and Internet topology, routing, and 180 addressing. 182 2. Requirements Notation 184 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 185 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 186 "OPTIONAL" in this document are to be interpreted as described in BCP 187 14 [RFC2119] [RFC8174] when, and only when, they appear in all 188 capitals, as shown here. 190 3. Definition of Terms 192 Address Family Identifier (AFI): AFI is a term used to describe an 193 address encoding in a packet. An address family that pertains to 194 addresses found in Data-Plane headers. See [AFN] and [RFC3232] 195 for details. An AFI value of 0 used in this specification 196 indicates an unspecified encoded address where the length of the 197 address is 0 octets following the 16-bit AFI value of 0. 199 Anycast Address: Anycast Address is a term used in this document to 200 refer to the same IPv4 or IPv6 address configured and used on 201 multiple systems at the same time. An EID or RLOC can be an 202 anycast address in each of their own address spaces. 204 Client-side: Client-side is a term used in this document to indicate 205 a connection initiation attempt by an end-system represented by an 206 EID. 208 Data-Probe: A Data-Probe is a LISP-encapsulated data packet where 209 the inner-header destination address equals the outer-header 210 destination address used to trigger a Map-Reply by a decapsulating 211 ETR. In addition, the original packet is decapsulated and 212 delivered to the destination host if the destination EID is in the 213 EID-Prefix range configured on the ETR. Otherwise, the packet is 214 discarded. A Data-Probe is used in some of the mapping database 215 designs to "probe" or request a Map-Reply from an ETR; in other 216 cases, Map-Requests are used. See each mapping database design 217 for details. When using Data-Probes, by sending Map-Requests on 218 the underlying routing system, EID-Prefixes must be advertised. 220 Egress Tunnel Router (ETR): An ETR is a router that accepts an IP 221 packet where the destination address in the "outer" IP header is 222 one of its own RLOCs. The router strips the "outer" header and 223 forwards the packet based on the next IP header found. In 224 general, an ETR receives LISP-encapsulated IP packets from the 225 Internet on one side and sends decapsulated IP packets to site 226 end-systems on the other side. ETR functionality does not have to 227 be limited to a router device. A server host can be the endpoint 228 of a LISP tunnel as well. 230 EID-to-RLOC Database: The EID-to-RLOC Database is a global 231 distributed database that contains all known EID-Prefix-to-RLOC 232 mappings. Each potential ETR typically contains a small piece of 233 the database: the EID-to-RLOC mappings for the EID-Prefixes 234 "behind" the router. These map to one of the router's own IP 235 addresses that are routable on the underlay. Note that there MAY 236 be transient conditions when the EID-Prefix for the site and 237 Locator-Set for each EID-Prefix may not be the same on all ETRs. 239 This has no negative implications, since a partial set of Locators 240 can be used. 242 EID-to-RLOC Map-Cache: The EID-to-RLOC Map-Cache is generally 243 short-lived, on-demand table in an ITR that stores, tracks, and is 244 responsible for timing out and otherwise validating EID-to-RLOC 245 mappings. This cache is distinct from the full "database" of EID- 246 to-RLOC mappings; it is dynamic, local to the ITR(s), and 247 relatively small, while the database is distributed, relatively 248 static, and much more global in scope to LISP nodes. 250 EID-Prefix: An EID-Prefix is a power-of-two block of EIDs that are 251 allocated to a site by an address allocation authority. EID- 252 Prefixes are associated with a set of RLOC addresses. EID-Prefix 253 allocations can be broken up into smaller blocks when an RLOC set 254 is to be associated with the larger EID-Prefix block. 256 End-System: An end-system is an IPv4 or IPv6 device that originates 257 packets with a single IPv4 or IPv6 header. The end-system 258 supplies an EID value for the destination address field of the IP 259 header when communicating outside of its routing domain. An end- 260 system can be a host computer, a switch or router device, or any 261 network appliance. 263 Endpoint ID (EID): An EID is a 32-bit (for IPv4) or 128-bit (for 264 IPv6) value used in the source and destination address fields of 265 the first (most inner) LISP header of a packet. The host obtains 266 a destination EID the same way it obtains a destination address 267 today, for example, through a Domain Name System (DNS) [RFC1034] 268 lookup or Session Initiation Protocol (SIP) [RFC3261] exchange. 269 The source EID is obtained via existing mechanisms used to set a 270 host's "local" IP address. An EID used on the public Internet 271 MUST have the same properties as any other IP address used in that 272 manner; this means, among other things, that it MUST be globally 273 unique. An EID is allocated to a host from an EID-Prefix block 274 associated with the site where the host is located. An EID can be 275 used by a host to refer to other hosts. Note that EID blocks MAY 276 be assigned in a hierarchical manner, independent of the network 277 topology, to facilitate scaling of the mapping database. In 278 addition, an EID block assigned to a site MAY have site-local 279 structure (subnetting) for routing within the site; this structure 280 is not visible to the underlay routing system. In theory, the bit 281 string that represents an EID for one device can represent an RLOC 282 for a different device. When used in discussions with other 283 Locator/ID separation proposals, a LISP EID will be called an 284 "LEID". Throughout this document, any references to "EID" refer 285 to an LEID. 287 Ingress Tunnel Router (ITR): An ITR is a router that resides in a 288 LISP site. Packets sent by sources inside of the LISP site to 289 destinations outside of the site are candidates for encapsulation 290 by the ITR. The ITR treats the IP destination address as an EID 291 and performs an EID-to-RLOC mapping lookup. The router then 292 prepends an "outer" IP header with one of its routable RLOCs (in 293 the RLOC space) in the source address field and the result of the 294 mapping lookup in the destination address field. Note that this 295 destination RLOC may be an intermediate, proxy device that has 296 better knowledge of the EID-to-RLOC mapping closer to the 297 destination EID. In general, an ITR receives IP packets from site 298 end-systems on one side and sends LISP-encapsulated IP packets 299 toward the Internet on the other side. 301 Specifically, when a service provider prepends a LISP header for 302 Traffic Engineering purposes, the router that does this is also 303 regarded as an ITR. The outer RLOC the ISP ITR uses can be based 304 on the outer destination address (the originating ITR's supplied 305 RLOC) or the inner destination address (the originating host's 306 supplied EID). 308 LISP Header: LISP header is a term used in this document to refer 309 to the outer IPv4 or IPv6 header, a UDP header, and a LISP- 310 specific 8-octet header that follow the UDP header and that an ITR 311 prepends or an ETR strips. 313 LISP Router: A LISP router is a router that performs the functions 314 of any or all of the following: ITR, ETR, RTR, Proxy-ITR (PITR), 315 or Proxy-ETR (PETR). 317 LISP Site: LISP site is a set of routers in an edge network that are 318 under a single technical administration. LISP routers that reside 319 in the edge network are the demarcation points to separate the 320 edge network from the core network. 322 Locator-Status-Bits (LSBs): Locator-Status-Bits are present in the 323 LISP header. They are used by ITRs to inform ETRs about the up/ 324 down status of all ETRs at the local site. These bits are used as 325 a hint to convey up/down router status and not path reachability 326 status. The LSBs can be verified by use of one of the Locator 327 reachability algorithms described in Section 10. An ETR MUST 328 rate-limit the action it takes when it detects changes in the 329 Locator-Status-Bits. 331 Negative Mapping Entry: A negative mapping entry, also known as a 332 negative cache entry, is an EID-to-RLOC entry where an EID-Prefix 333 is advertised or stored with no RLOCs. That is, the Locator-Set 334 for the EID-to-RLOC entry is empty, one with an encoded Locator 335 count of 0. This type of entry could be used to describe a prefix 336 from a non-LISP site, which is explicitly not in the mapping 337 database. There are a set of well-defined actions that are 338 encoded in a Negative Map-Reply. 340 Proxy-ETR (PETR): A PETR is defined and described in [RFC6832]. A 341 PETR acts like an ETR but does so on behalf of LISP sites that 342 send packets to destinations at non-LISP sites. 344 Proxy-ITR (PITR): A PITR is defined and described in [RFC6832]. A 345 PITR acts like an ITR but does so on behalf of non-LISP sites that 346 send packets to destinations at LISP sites. 348 Recursive Tunneling: Recursive Tunneling occurs when a packet has 349 more than one LISP IP header. Additional layers of tunneling MAY 350 be employed to implement Traffic Engineering or other re-routing 351 as needed. When this is done, an additional "outer" LISP header 352 is added, and the original RLOCs are preserved in the "inner" 353 header. 355 Re-Encapsulating Tunneling Router (RTR): An RTR acts like an ETR to 356 remove a LISP header, then acts as an ITR to prepend a new LISP 357 header. This is known as Re-encapsulating Tunneling. Doing this 358 allows a packet to be re-routed by the RTR without adding the 359 overhead of additional tunnel headers. When using multiple 360 mapping database systems, care must be taken to not create re- 361 encapsulation loops through misconfiguration. 363 Route-Returnability: Route-returnability is an assumption that the 364 underlying routing system will deliver packets to the destination. 365 When combined with a nonce that is provided by a sender and 366 returned by a receiver, this limits off-path data insertion. A 367 route-returnability check is verified when a message is sent with 368 a nonce, another message is returned with the same nonce, and the 369 destination of the original message appears as the source of the 370 returned message. 372 Routing Locator (RLOC): An RLOC is an IPv4 [RFC0791] or IPv6 373 [RFC8200] address of an Egress Tunnel Router (ETR). An RLOC is 374 the output of an EID-to-RLOC mapping lookup. An EID maps to zero 375 or more RLOCs. Typically, RLOCs are numbered from blocks that are 376 assigned to a site at each point to which it attaches to the 377 underlay network; where the topology is defined by the 378 connectivity of provider networks. Multiple RLOCs can be assigned 379 to the same ETR device or to multiple ETR devices at a site. 381 Server-side: Server-side is a term used in this document to indicate 382 that a connection initiation attempt is being accepted for a 383 destination EID. 385 TE-ETR: A TE-ETR is an ETR that is deployed in a service provider 386 network that strips an outer LISP header for Traffic Engineering 387 purposes. 389 TE-ITR: A TE-ITR is an ITR that is deployed in a service provider 390 network that prepends an additional LISP header for Traffic 391 Engineering purposes. 393 xTR: An xTR is a reference to an ITR or ETR when direction of data 394 flow is not part of the context description. "xTR" refers to the 395 router that is the tunnel endpoint and is used synonymously with 396 the term "Tunnel Router". For example, "An xTR can be located at 397 the Customer Edge (CE) router" indicates both ITR and ETR 398 functionality at the CE router. 400 4. Basic Overview 402 One key concept of LISP is that end-systems operate the same way they 403 do today. The IP addresses that hosts use for tracking sockets and 404 connections, and for sending and receiving packets, do not change. 405 In LISP terminology, these IP addresses are called Endpoint 406 Identifiers (EIDs). 408 Routers continue to forward packets based on IP destination 409 addresses. When a packet is LISP encapsulated, these addresses are 410 referred to as Routing Locators (RLOCs). Most routers along a path 411 between two hosts will not change; they continue to perform routing/ 412 forwarding lookups on the destination addresses. For routers between 413 the source host and the ITR as well as routers from the ETR to the 414 destination host, the destination address is an EID. For the routers 415 between the ITR and the ETR, the destination address is an RLOC. 417 Another key LISP concept is the "Tunnel Router". A Tunnel Router 418 prepends LISP headers on host-originated packets and strips them 419 prior to final delivery to their destination. The IP addresses in 420 this "outer header" are RLOCs. During end-to-end packet exchange 421 between two Internet hosts, an ITR prepends a new LISP header to each 422 packet, and an ETR strips the new header. The ITR performs EID-to- 423 RLOC lookups to determine the routing path to the ETR, which has the 424 RLOC as one of its IP addresses. 426 Some basic rules governing LISP are: 428 o End-systems only send to addresses that are EIDs. EIDs are 429 typically IP addresses assigned to hosts (other types of EID are 430 supported by LISP, see [RFC8060] for further information). End- 431 systems don't know that addresses are EIDs versus RLOCs but assume 432 that packets get to their intended destinations. In a system 433 where LISP is deployed, LISP routers intercept EID-addressed 434 packets and assist in delivering them across the network core 435 where EIDs cannot be routed. The procedure a host uses to send IP 436 packets does not change. 438 o LISP routers mostly deal with Routing Locator addresses. See 439 details in Section 4.1 to clarify what is meant by "mostly". 441 o RLOCs are always IP addresses assigned to routers, preferably 442 topologically oriented addresses from provider CIDR (Classless 443 Inter-Domain Routing) blocks. 445 o When a router originates packets, it MAY use as a source address 446 either an EID or RLOC. When acting as a host (e.g., when 447 terminating a transport session such as Secure SHell (SSH), 448 TELNET, or the Simple Network Management Protocol (SNMP)), it MAY 449 use an EID that is explicitly assigned for that purpose. An EID 450 that identifies the router as a host MUST NOT be used as an RLOC; 451 an EID is only routable within the scope of a site. A typical BGP 452 configuration might demonstrate this "hybrid" EID/RLOC usage where 453 a router could use its "host-like" EID to terminate iBGP sessions 454 to other routers in a site while at the same time using RLOCs to 455 terminate eBGP sessions to routers outside the site. 457 o Packets with EIDs in them are not expected to be delivered end-to- 458 end in the absence of an EID-to-RLOC mapping operation. They are 459 expected to be used locally for intra-site communication or to be 460 encapsulated for inter-site communication. 462 o EIDs MAY also be structured (subnetted) in a manner suitable for 463 local routing within an Autonomous System (AS). 465 An additional LISP header MAY be prepended to packets by a TE-ITR 466 when re-routing of the path for a packet is desired. A potential 467 use-case for this would be an ISP router that needs to perform 468 Traffic Engineering for packets flowing through its network. In such 469 a situation, termed "Recursive Tunneling", an ISP transit acts as an 470 additional ITR, and the destination RLOC it uses for the new 471 prepended header would be either a TE-ETR within the ISP (along an 472 intra-ISP traffic engineered path) or a TE-ETR within another ISP (an 473 inter-ISP traffic engineered path, where an agreement to build such a 474 path exists). 476 In order to avoid excessive packet overhead as well as possible 477 encapsulation loops, this document recommends that a maximum of two 478 LISP headers can be prepended to a packet. For initial LISP 479 deployments, it is assumed that two headers is sufficient, where the 480 first prepended header is used at a site for Location/Identity 481 separation and the second prepended header is used inside a service 482 provider for Traffic Engineering purposes. 484 Tunnel Routers can be placed fairly flexibly in a multi-AS topology. 485 For example, the ITR for a particular end-to-end packet exchange 486 might be the first-hop or default router within a site for the source 487 host. Similarly, the ETR might be the last-hop router directly 488 connected to the destination host. Another example, perhaps for a 489 VPN service outsourced to an ISP by a site, the ITR could be the 490 site's border router at the service provider attachment point. 491 Mixing and matching of site-operated, ISP-operated, and other Tunnel 492 Routers is allowed for maximum flexibility. 494 4.1. Packet Flow Sequence 496 This section provides an example of the unicast packet flow, 497 including also Control-Plane information as specified in 498 [I-D.ietf-lisp-rfc6833bis]. The example also assumes the following 499 conditions: 501 o Source host "host1.abc.example.com" is sending a packet to 502 "host2.xyz.example.com", exactly what host1 would do if the site 503 was not using LISP. 505 o Each site is multihomed, so each Tunnel Router has an address 506 (RLOC) assigned from the service provider address block for each 507 provider to which that particular Tunnel Router is attached. 509 o The ITR(s) and ETR(s) are directly connected to the source and 510 destination, respectively, but the source and destination can be 511 located anywhere in the LISP site. 513 o A Map-Request is sent for an external destination when the 514 destination is not found in the forwarding table or matches a 515 default route. Map-Requests are sent to the mapping database 516 system by using the LISP Control-Plane protocol documented in 517 [I-D.ietf-lisp-rfc6833bis]. 519 o Map-Replies are sent on the underlying routing system topology 520 using the [I-D.ietf-lisp-rfc6833bis] Control-Plane protocol. 522 Client host1.abc.example.com wants to communicate with server 523 host2.xyz.example.com: 525 1. host1.abc.example.com wants to open a TCP connection to 526 host2.xyz.example.com. It does a DNS lookup on 527 host2.xyz.example.com. An A/AAAA record is returned. This 528 address is the destination EID. The locally assigned address of 529 host1.abc.example.com is used as the source EID. An IPv4 or IPv6 530 packet is built and forwarded through the LISP site as a normal 531 IP packet until it reaches a LISP ITR. 533 2. The LISP ITR must be able to map the destination EID to an RLOC 534 of one of the ETRs at the destination site. The specific method 535 used to do this is not described in this example. See 536 [I-D.ietf-lisp-rfc6833bis] for further information. 538 3. The ITR sends a LISP Map-Request as specified in 539 [I-D.ietf-lisp-rfc6833bis]. Map-Requests SHOULD be rate-limited. 541 4. The mapping system helps forwarding the Map-Request to the 542 corresponding ETR. When the Map-Request arrives at one of the 543 ETRs at the destination site, it will process the packet as a 544 control message. 546 5. The ETR looks at the destination EID of the Map-Request and 547 matches it against the prefixes in the ETR's configured EID-to- 548 RLOC mapping database. This is the list of EID-Prefixes the ETR 549 is supporting for the site it resides in. If there is no match, 550 the Map-Request is dropped. Otherwise, a LISP Map-Reply is 551 returned to the ITR. 553 6. The ITR receives the Map-Reply message, parses the message (to 554 check for format validity), and stores the mapping information 555 from the packet. This information is stored in the ITR's EID-to- 556 RLOC Map-Cache. Note that the Map-Cache is an on-demand cache. 557 An ITR will manage its Map-Cache in such a way that optimizes for 558 its resource constraints. 560 7. Subsequent packets from host1.abc.example.com to 561 host2.xyz.example.com will have a LISP header prepended by the 562 ITR using the appropriate RLOC as the LISP header destination 563 address learned from the ETR. Note that the packet MAY be sent 564 to a different ETR than the one that returned the Map-Reply due 565 to the source site's hashing policy or the destination site's 566 Locator-Set policy. 568 8. The ETR receives these packets directly (since the destination 569 address is one of its assigned IP addresses), checks the validity 570 of the addresses, strips the LISP header, and forwards packets to 571 the attached destination host. 573 9. In order to defer the need for a mapping lookup in the reverse 574 direction, an ETR can OPTIONALLY create a cache entry that maps 575 the source EID (inner-header source IP address) to the source 576 RLOC (outer-header source IP address) in a received LISP packet. 577 Such a cache entry is termed a "glean mapping" and only contains 578 a single RLOC for the EID in question. More complete information 579 about additional RLOCs SHOULD be verified by sending a LISP Map- 580 Request for that EID. Both the ITR and the ETR MAY also 581 influence the decision the other makes in selecting an RLOC. 583 5. LISP Encapsulation Details 585 Since additional tunnel headers are prepended, the packet becomes 586 larger and can exceed the MTU of any link traversed from the ITR to 587 the ETR. It is RECOMMENDED in IPv4 that packets do not get 588 fragmented as they are encapsulated by the ITR. Instead, the packet 589 is dropped and an ICMP Unreachable/Fragmentation-Needed message is 590 returned to the source. 592 In the case when fragmentation is needed, this specification 593 RECOMMENDS that implementations provide support for one of the 594 proposed fragmentation and reassembly schemes. Two existing schemes 595 are detailed in Section 7. 597 Since IPv4 or IPv6 addresses can be either EIDs or RLOCs, the LISP 598 architecture supports IPv4 EIDs with IPv6 RLOCs (where the inner 599 header is in IPv4 packet format and the outer header is in IPv6 600 packet format) or IPv6 EIDs with IPv4 RLOCs (where the inner header 601 is in IPv6 packet format and the outer header is in IPv4 packet 602 format). The next sub-sections illustrate packet formats for the 603 homogeneous case (IPv4-in-IPv4 and IPv6-in-IPv6), but all 4 604 combinations MUST be supported. Additional types of EIDs are defined 605 in [RFC8060]. 607 As LISP uses UDP encapsulation to carry traffic between xTRs across 608 the Internet, implementors should be aware of the provisions of 609 [RFC8085], especially those given in section 3.1.11 on congestion 610 control for UDP tunneling. 612 Implementors are encouraged to consider UDP checksum usage guidelines 613 in section 3.4 of [RFC8085] when it is desirable to protect UDP and 614 LISP headers against corruption. 616 5.1. LISP IPv4-in-IPv4 Header Format 617 0 1 2 3 618 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 1 619 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 620 / |Version| IHL | DSCP |ECN| Total Length | 621 / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 622 | | Identification |Flags| Fragment Offset | 623 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 624 OH | Time to Live | Protocol = 17 | Header Checksum | 625 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 626 | | Source Routing Locator | 627 \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 628 \ | Destination Routing Locator | 629 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 630 / | Source Port = xxxx | Dest Port = 4341 | 631 UDP +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 632 \ | UDP Length | UDP Checksum | 633 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 634 L |N|L|E|V|I|R|K|K| Nonce/Map-Version | 635 I \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 636 S / | Instance ID/Locator-Status-Bits | 637 P +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 638 / |Version| IHL | DSCP |ECN| Total Length | 639 / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 640 | | Identification |Flags| Fragment Offset | 641 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 642 IH | Time to Live | Protocol | Header Checksum | 643 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 644 | | Source EID | 645 \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 646 \ | Destination EID | 647 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 649 IHL = IP-Header-Length 651 5.2. LISP IPv6-in-IPv6 Header Format 653 0 1 2 3 654 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 1 655 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 656 / |Version| DSCP |ECN| Flow Label | 657 / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 658 | | Payload Length | Next Header=17| Hop Limit | 659 v +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 660 | | 661 O + + 662 u | | 663 t + Source Routing Locator + 664 e | | 665 r + + 666 | | 667 H +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 668 d | | 669 r + + 670 | | 671 ^ + Destination Routing Locator + 672 | | | 673 \ + + 674 \ | | 675 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 676 / | Source Port = xxxx | Dest Port = 4341 | 677 UDP +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 678 \ | UDP Length | UDP Checksum | 679 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 680 L |N|L|E|V|I|R|K|K| Nonce/Map-Version | 681 I \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 682 S / | Instance ID/Locator-Status-Bits | 683 P +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 684 / |Version| DSCP |ECN| Flow Label | 685 / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 686 / | Payload Length | Next Header | Hop Limit | 687 v +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 688 | | 689 I + + 690 n | | 691 n + Source EID + 692 e | | 693 r + + 694 | | 695 H +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 696 d | | 697 r + + 698 | | 699 ^ + Destination EID + 700 \ | | 701 \ + + 702 \ | | 703 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 705 5.3. Tunnel Header Field Descriptions 707 Inner Header (IH): The inner header is the header on the 708 datagram received from the originating host [RFC0791] [RFC8200] 709 [RFC2474]. The source and destination IP addresses are EIDs. 711 Outer Header: (OH) The outer header is a new header prepended by an 712 ITR. The address fields contain RLOCs obtained from the ingress 713 router's EID-to-RLOC Cache. The IP protocol number is "UDP (17)" 714 from [RFC0768]. The setting of the Don't Fragment (DF) bit 715 'Flags' field is according to rules listed in Sections 7.1 and 716 7.2. 718 UDP Header: The UDP header contains an ITR selected source port when 719 encapsulating a packet. See Section 12 for details on the hash 720 algorithm used to select a source port based on the 5-tuple of the 721 inner header. The destination port MUST be set to the well-known 722 IANA-assigned port value 4341. 724 UDP Checksum: The 'UDP Checksum' field SHOULD be transmitted as zero 725 by an ITR for either IPv4 [RFC0768] and IPv6 encapsulation 726 [RFC6935] [RFC6936]. When a packet with a zero UDP checksum is 727 received by an ETR, the ETR MUST accept the packet for 728 decapsulation. When an ITR transmits a non-zero value for the UDP 729 checksum, it MUST send a correctly computed value in this field. 730 When an ETR receives a packet with a non-zero UDP checksum, it MAY 731 choose to verify the checksum value. If it chooses to perform 732 such verification, and the verification fails, the packet MUST be 733 silently dropped. If the ETR chooses not to perform the 734 verification, or performs the verification successfully, the 735 packet MUST be accepted for decapsulation. The handling of UDP 736 zero checksums over IPv6 for all tunneling protocols, including 737 LISP, is subject to the applicability statement in [RFC6936]. 739 UDP Length: The 'UDP Length' field is set for an IPv4-encapsulated 740 packet to be the sum of the inner-header IPv4 Total Length plus 741 the UDP and LISP header lengths. For an IPv6-encapsulated packet, 742 the 'UDP Length' field is the sum of the inner-header IPv6 Payload 743 Length, the size of the IPv6 header (40 octets), and the size of 744 the UDP and LISP headers. 746 N: The N-bit is the nonce-present bit. When this bit is set to 1, 747 the low-order 24 bits of the first 32 bits of the LISP header 748 contain a Nonce. See Section 10.1 for details. Both N- and 749 V-bits MUST NOT be set in the same packet. If they are, a 750 decapsulating ETR MUST treat the 'Nonce/Map-Version' field as 751 having a Nonce value present. 753 L: The L-bit is the 'Locator-Status-Bits' field enabled bit. When 754 this bit is set to 1, the Locator-Status-Bits in the second 755 32 bits of the LISP header are in use. 757 x 1 x x 0 x x x 758 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 759 |N|L|E|V|I|R|K|K| Nonce/Map-Version | 760 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 761 | Locator-Status-Bits | 762 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 764 E: The E-bit is the echo-nonce-request bit. This bit MUST be ignored 765 and has no meaning when the N-bit is set to 0. When the N-bit is 766 set to 1 and this bit is set to 1, an ITR is requesting that the 767 nonce value in the 'Nonce' field be echoed back in LISP- 768 encapsulated packets when the ITR is also an ETR. See 769 Section 10.1 for details. 771 V: The V-bit is the Map-Version present bit. When this bit is set to 772 1, the N-bit MUST be 0. Refer to Section 13.1 for more details. 773 This bit indicates that the LISP header is encoded in this 774 case as: 776 0 x 0 1 x x x x 777 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 778 |N|L|E|V|I|R|K|K| Source Map-Version | Dest Map-Version | 779 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 780 | Instance ID/Locator-Status-Bits | 781 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 783 I: The I-bit is the Instance ID bit. See Section 8 for more details. 784 When this bit is set to 1, the 'Locator-Status-Bits' field is 785 reduced to 8 bits and the high-order 24 bits are used as an 786 Instance ID. If the L-bit is set to 0, then the low-order 8 bits 787 are transmitted as zero and ignored on receipt. The format of the 788 LISP header would look like this: 790 x x x x 1 x x x 791 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 792 |N|L|E|V|I|R|K|K| Nonce/Map-Version | 793 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 794 | Instance ID | LSBs | 795 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 797 R: The R-bit is a Reserved bit for future use. It MUST be set to 0 798 on transmit and MUST be ignored on receipt. 800 KK: The KK-bits are a 2-bit field used when encapsulated packets are 801 encrypted. The field is set to 00 when the packet is not 802 encrypted. See [RFC8061] for further information. 804 LISP Nonce: The LISP 'Nonce' field is a 24-bit value that is 805 randomly generated by an ITR when the N-bit is set to 1. Nonce 806 generation algorithms are an implementation matter but are 807 required to generate different nonces when sending to different 808 RLOCs. However, the same nonce can be used for a period of time 809 when encapsulating to the same ETR. The nonce is also used when 810 the E-bit is set to request the nonce value to be echoed by the 811 other side when packets are returned. When the E-bit is clear but 812 the N-bit is set, a remote ITR is either echoing a previously 813 requested echo-nonce or providing a random nonce. See 814 Section 10.1 for more details. 816 LISP Locator-Status-Bits (LSBs): When the L-bit is also set, the 817 'Locator-Status-Bits' field in the LISP header is set by an ITR to 818 indicate to an ETR the up/down status of the Locators in the 819 source site. Each RLOC in a Map-Reply is assigned an ordinal 820 value from 0 to n-1 (when there are n RLOCs in a mapping entry). 821 The Locator-Status-Bits are numbered from 0 to n-1 from the least 822 significant bit of the field. The field is 32 bits when the I-bit 823 is set to 0 and is 8 bits when the I-bit is set to 1. When a 824 Locator-Status-Bit is set to 1, the ITR is indicating to the ETR 825 that the RLOC associated with the bit ordinal has up status. See 826 Section 10 for details on how an ITR can determine the status of 827 the ETRs at the same site. When a site has multiple EID-Prefixes 828 that result in multiple mappings (where each could have a 829 different Locator-Set), the Locator-Status-Bits setting in an 830 encapsulated packet MUST reflect the mapping for the EID-Prefix 831 that the inner-header source EID address matches. If the LSB for 832 an anycast Locator is set to 1, then there is at least one RLOC 833 with that address, and the ETR is considered 'up'. 835 When doing ITR/PITR encapsulation: 837 o The outer-header 'Time to Live' field (or 'Hop Limit' field, in 838 the case of IPv6) SHOULD be copied from the inner-header 'Time to 839 Live' field. 841 o The outer-header 'Differentiated Services Code Point' (DSCP) field 842 (or the 'Traffic Class' field, in the case of IPv6) SHOULD be 843 copied from the inner-header DSCP field ('Traffic Class' field, in 844 the case of IPv6) to the outer-header. 846 o The 'Explicit Congestion Notification' (ECN) field (bits 6 and 7 847 of the IPv6 'Traffic Class' field) requires special treatment in 848 order to avoid discarding indications of congestion [RFC6040]. 849 ITR encapsulation MUST copy the 2-bit 'ECN' field from the inner 850 header to the outer header. Re-encapsulation MUST copy the 2-bit 851 'ECN' field from the stripped outer header to the new outer 852 header. 854 When doing ETR/PETR decapsulation: 856 o The inner-header 'Time to Live' field (or 'Hop Limit' field, in 857 the case of IPv6) MUST be copied from the outer-header 'Time to 858 Live' field, when the Time to Live value of the outer header is 859 less than the Time to Live value of the inner header. Failing to 860 perform this check can cause the Time to Live of the inner header 861 to increment across encapsulation/decapsulation cycles. This 862 check is also performed when doing initial encapsulation, when a 863 packet comes to an ITR or PITR destined for a LISP site. 865 o The outer-header 'Differentiated Services Code Point' (DSCP) field 866 (or the 'Traffic Class' field, in the case of IPv6) SHOULD be 867 copied from the outer-header DSCP field ('Traffic Class' field, in 868 the case of IPv6) to the inner-header. 870 o The 'Explicit Congestion Notification' (ECN) field (bits 6 and 7 871 of the IPv6 'Traffic Class' field) requires special treatment in 872 order to avoid discarding indications of congestion [RFC6040]. If 873 the 'ECN' field contains a congestion indication codepoint (the 874 value is '11', the Congestion Experienced (CE) codepoint), then 875 ETR decapsulation MUST copy the 2-bit 'ECN' field from the 876 stripped outer header to the surviving inner header that is used 877 to forward the packet beyond the ETR. These requirements preserve 878 CE indications when a packet that uses ECN traverses a LISP tunnel 879 and becomes marked with a CE indication due to congestion between 880 the tunnel endpoints. Implementations exist that copy the 'ECN' 881 field from the outer header to the inner header even though 882 [RFC6040] does not recommend this behavior. It is RECOMMENDED 883 that implementations change to support the behavior in [RFC6040]. 885 Note that if an ETR/PETR is also an ITR/PITR and chooses to re- 886 encapsulate after decapsulating, the net effect of this is that the 887 new outer header will carry the same Time to Live as the old outer 888 header minus 1. 890 Copying the Time to Live (TTL) serves two purposes: first, it 891 preserves the distance the host intended the packet to travel; 892 second, and more importantly, it provides for suppression of looping 893 packets in the event there is a loop of concatenated tunnels due to 894 misconfiguration. 896 The Explicit Congestion Notification ('ECN') field occupies bits 6 897 and 7 of both the IPv4 'Type of Service' field and the IPv6 'Traffic 898 Class' field [RFC6040]. The 'ECN' field requires special treatment 899 in order to avoid discarding indications of congestion [RFC6040]. An 900 ITR/PITR encapsulation MUST copy the 2-bit 'ECN' field from the inner 901 header to the outer header. Re-encapsulation MUST copy the 2-bit 902 'ECN' field from the stripped outer header to the new outer header. 903 If the 'ECN' field contains a congestion indication codepoint (the 904 value is '11', the Congestion Experienced (CE) codepoint), then ETR/ 905 PETR decapsulation MUST copy the 2-bit 'ECN' field from the stripped 906 outer header to the surviving inner header that is used to forward 907 the packet beyond the ETR. These requirements preserve CE 908 indications when a packet that uses ECN traverses a LISP tunnel and 909 becomes marked with a CE indication due to congestion between the 910 tunnel endpoints. 912 6. LISP EID-to-RLOC Map-Cache 914 ITRs and PITRs maintain an on-demand cache, referred as LISP EID-to- 915 RLOC Map-Cache, that contains mappings from EID-prefixes to locator 916 sets. The cache is used to encapsulate packets from the EID space to 917 the corresponding RLOC network attachment point. 919 When an ITR/PITR receives a packet from inside of the LISP site to 920 destinations outside of the site a longest-prefix match lookup of the 921 EID is done to the Map-Cache. 923 When the lookup succeeds, the Locator-Set retrieved from the Map- 924 Cache is used to send the packet to the EID's topological location. 926 If the lookup fails, the ITR/PITR needs to retrieve the mapping using 927 the LISP Control-Plane protocol [I-D.ietf-lisp-rfc6833bis]. The 928 mapping is then stored in the local Map-Cache to forward subsequent 929 packets addressed to the same EID-prefix. 931 The Map-Cache is a local cache of mappings, entries are expired based 932 on the associated Time to live. In addition, entries can be updated 933 with more current information, see Section 13 for further information 934 on this. Finally, the Map-Cache also contains reachability 935 information about EIDs and RLOCs, and uses LISP reachability 936 information mechanisms to determine the reachability of RLOCs, see 937 Section 10 for the specific mechanisms. 939 7. Dealing with Large Encapsulated Packets 941 This section proposes two mechanisms to deal with packets that exceed 942 the path MTU between the ITR and ETR. 944 It is left to the implementor to decide if the stateless or stateful 945 mechanism SHOULD be implemented. Both or neither can be used, since 946 it is a local decision in the ITR regarding how to deal with MTU 947 issues, and sites can interoperate with differing mechanisms. 949 Both stateless and stateful mechanisms also apply to Re-encapsulating 950 and Recursive Tunneling, so any actions below referring to an ITR 951 also apply to a TE-ITR. 953 7.1. A Stateless Solution to MTU Handling 955 An ITR stateless solution to handle MTU issues is described as 956 follows: 958 1. Define H to be the size, in octets, of the outer header an ITR 959 prepends to a packet. This includes the UDP and LISP header 960 lengths. 962 2. Define L to be the size, in octets, of the maximum-sized packet 963 an ITR can send to an ETR without the need for the ITR or any 964 intermediate routers to fragment the packet. 966 3. Define an architectural constant S for the maximum size of a 967 packet, in octets, an ITR MUST receive from the source so the 968 effective MTU can be met. That is, L = S + H. 970 When an ITR receives a packet from a site-facing interface and adds H 971 octets worth of encapsulation to yield a packet size greater than L 972 octets (meaning the received packet size was greater than S octets 973 from the source), it resolves the MTU issue by first splitting the 974 original packet into 2 equal-sized fragments. A LISP header is then 975 prepended to each fragment. The size of the encapsulated fragments 976 is then (S/2 + H), which is less than the ITR's estimate of the path 977 MTU between the ITR and its correspondent ETR. 979 When an ETR receives encapsulated fragments, it treats them as two 980 individually encapsulated packets. It strips the LISP headers and 981 then forwards each fragment to the destination host of the 982 destination site. The two fragments are reassembled at the 983 destination host into the single IP datagram that was originated by 984 the source host. Note that reassembly can happen at the ETR if the 985 encapsulated packet was fragmented at or after the ITR. 987 This behavior MUST be performed by the ITR only when the source host 988 originates a packet with the 'DF' field of the IP header set to 0. 989 When the 'DF' field of the IP header is set to 1, or the packet is an 990 IPv6 packet originated by the source host, the ITR will drop the 991 packet when the size is greater than L and send an ICMPv4 ICMP 992 Unreachable/Fragmentation-Needed or ICMPv6 "Packet Too Big" message 993 to the source with a value of S, where S is (L - H). 995 When the outer-header encapsulation uses an IPv4 header, an 996 implementation SHOULD set the DF bit to 1 so ETR fragment reassembly 997 can be avoided. An implementation MAY set the DF bit in such headers 998 to 0 if it has good reason to believe there are unresolvable path MTU 999 issues between the sending ITR and the receiving ETR. 1001 This specification RECOMMENDS that L be defined as 1500. 1003 7.2. A Stateful Solution to MTU Handling 1005 An ITR stateful solution to handle MTU issues is described as follows 1006 and was first introduced in [OPENLISP]: 1008 1. The ITR will keep state of the effective MTU for each Locator per 1009 Map-Cache entry. The effective MTU is what the core network can 1010 deliver along the path between the ITR and ETR. 1012 2. When an IPv6-encapsulated packet, or an IPv4-encapsulated packet 1013 with the DF bit set to 1, exceeds what the core network can 1014 deliver, one of the intermediate routers on the path will send an 1015 ICMPv6 "Packet Too Big" message or an ICMPv4 Unreachable/ 1016 Fragmentation-Needed to the ITR, respectively. The ITR will 1017 parse the ICMP message to determine which Locator is affected by 1018 the effective MTU change and then record the new effective MTU 1019 value in the Map-Cache entry. 1021 3. When a packet is received by the ITR from a source inside of the 1022 site and the size of the packet is greater than the effective MTU 1023 stored with the Map-Cache entry associated with the destination 1024 EID the packet is for, the ITR will send an ICMPv4 ICMP 1025 Unreachable/Fragmentation-Needed or ICMPv6 "Packet Too Big" 1026 message back to the source. The packet size advertised by the 1027 ITR in the ICMP message is the effective MTU minus the LISP 1028 encapsulation length. 1030 Even though this mechanism is stateful, it has advantages over the 1031 stateless IP fragmentation mechanism, by not involving the 1032 destination host with reassembly of ITR fragmented packets. 1034 8. Using Virtualization and Segmentation with LISP 1036 There are several cases where segregation is needed at the EID level. 1037 For instance, this is the case for deployments containing overlapping 1038 addresses, traffic isolation policies or multi-tenant virtualization. 1039 For these and other scenarios where segregation is needed, Instance 1040 IDs are used. 1042 An Instance ID can be carried in a LISP-encapsulated packet. An ITR 1043 that prepends a LISP header will copy a 24-bit value used by the LISP 1044 router to uniquely identify the address space. The value is copied 1045 to the 'Instance ID' field of the LISP header, and the I-bit is set 1046 to 1. 1048 When an ETR decapsulates a packet, the Instance ID from the LISP 1049 header is used as a table identifier to locate the forwarding table 1050 to use for the inner destination EID lookup. 1052 For example, an 802.1Q VLAN tag or VPN identifier could be used as a 1053 24-bit Instance ID. See [I-D.ietf-lisp-vpn] for LISP VPN use-case 1054 details. 1056 The Instance ID that is stored in the mapping database when LISP-DDT 1057 [RFC8111] is used is 32 bits in length. That means the Control-Plane 1058 can store more instances than a given Data-Plane can use. Multiple 1059 Data-Planes can use the same 32-bit space as long as the low-order 24 1060 bits don't overlap among xTRs. 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 RLOC 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 maping 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. Control is shared by the server- 1101 side determining the list and the client-side determining load 1102 distribution. Again, the client can use alternative RLOCs if the 1103 server-provided list of RLOCs is unreachable. 1105 o Either side (more likely the server-side ETR) decides not to send 1106 a Map-Request. For example, if the server-side ETR does not send 1107 Map-Requests, it gleans RLOCs from the client-side ITR, giving the 1108 client-side ITR responsibility for bidirectional RLOC reachability 1109 and preferability. Server-side ETR gleaning of the client-side 1110 ITR RLOC is done by caching the inner-header source EID and the 1111 outer-header source RLOC of received packets. The client-side ITR 1112 controls how traffic is returned and can alternate using an outer- 1113 header source RLOC, which then can be added to the list the 1114 server-side ETR uses to return traffic. Since no Priority or 1115 Weights are provided using this method, the server-side ETR MUST 1116 assume that each client-side ITR RLOC uses the same best Priority 1117 with a Weight of zero. In addition, since EID-Prefix encoding 1118 cannot be conveyed in data packets, the EID-to-RLOC Cache on 1119 Tunnel Routers can grow to be very large. 1121 Instead of using the Map-Cache or mapping system, RLOC information 1122 MAY be gleaned from received tunneled packets or Map-Request 1123 messages. A "gleaned" Map-Cache entry, one learned from the source 1124 RLOC of a received encapsulated packet, is only stored and used for a 1125 few seconds, pending verification. Verification is performed by 1126 sending a Map-Request to the source EID (the inner-header IP source 1127 address) of the received encapsulated packet. A reply to this 1128 "verifying Map-Request" is used to fully populate the Map-Cache entry 1129 for the "gleaned" EID and is stored and used for the time indicated 1130 from the 'TTL' field of a received Map-Reply. When a verified Map- 1131 Cache entry is stored, data gleaning no longer occurs for subsequent 1132 packets that have a source EID that matches the EID-Prefix of the 1133 verified entry. This "gleaning" mechanism is OPTIONAL, refer to 1134 Section 16 for security issues regarding 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. 1162 3. An ITR/ETR pair can use the 'Echo-Noncing' Locator reachability 1163 algorithms described in this section. 1165 When determining Locator up/down reachability by examining the 1166 Locator-Status-Bits from the LISP-encapsulated data packet, an ETR 1167 will receive up-to-date status from an encapsulating ITR about 1168 reachability for all ETRs at the site. CE-based ITRs at the source 1169 site can determine reachability relative to each other using the site 1170 IGP as follows: 1172 o Under normal circumstances, each ITR will advertise a default 1173 route into the site IGP. 1175 o If an ITR fails or if the upstream link to its PE fails, its 1176 default route will either time out or be withdrawn. 1178 Each ITR can thus observe the presence or lack of a default route 1179 originated by the others to determine the Locator-Status-Bits it sets 1180 for them. 1182 When ITRs at the site are not deployed in CE routers, the IGP can 1183 still be used to determine the reachability of Locators, provided 1184 they are injected into the IGP. This is typically done when a /32 1185 address is configured on a loopback interface. 1187 RLOCs listed in a Map-Reply are numbered with ordinals 0 to n-1. The 1188 Locator-Status-Bits in a LISP-encapsulated packet are numbered from 0 1189 to n-1 starting with the least significant bit. For example, if an 1190 RLOC listed in the 3rd position of the Map-Reply goes down (ordinal 1191 value 2), then all ITRs at the site will clear the 3rd least 1192 significant bit (xxxx x0xx) of the 'Locator-Status-Bits' field for 1193 the packets they encapsulate. 1195 When an ETR decapsulates a packet, it will check for any change in 1196 the 'Locator-Status-Bits' field. When a bit goes from 1 to 0, the 1197 ETR, if acting also as an ITR, will refrain from encapsulating 1198 packets to an RLOC that is indicated as down. It will only resume 1199 using that RLOC if the corresponding Locator-Status-Bit returns to a 1200 value of 1. Locator-Status-Bits are associated with a Locator-Set 1201 per EID-Prefix. Therefore, when a Locator becomes unreachable, the 1202 Locator-Status-Bit that corresponds to that Locator's position in the 1203 list returned by the last Map-Reply will be set to zero for that 1204 particular EID-Prefix. Refer to Section 16 for security related 1205 issues regarding Locator-Status-Bits. 1207 If an ITR encapsulates a packet to an ETR and the packet is received 1208 and decapsulated by the ETR, it is implied but not confirmed by the 1209 ITR that the ETR's RLOC is reachable. In most cases, the ETR can 1210 also reach the ITR but cannot assume this to be true, due to the 1211 possibility of path asymmetry. In the presence of unidirectional 1212 traffic flow from an ITR to an ETR, the ITR SHOULD NOT use the lack 1213 of return traffic as an indication that the ETR is unreachable. 1214 Instead, it MUST use an alternate mechanism to determine 1215 reachability. 1217 The security considerations of Section 16 related with data-plane 1218 reachability applies to the data-plane RLOC reachability mechanisms 1219 described in this section. 1221 10.1. Echo Nonce Algorithm 1223 When data flows bidirectionally between Locators from different 1224 sites, a Data-Plane mechanism called "nonce echoing" can be used to 1225 determine reachability between an ITR and ETR. When an ITR wants to 1226 solicit a nonce echo, it sets the N- and E-bits and places a 24-bit 1227 nonce [RFC4086] in the LISP header of the next encapsulated data 1228 packet. 1230 When this packet is received by the ETR, the encapsulated packet is 1231 forwarded as normal. When the ETR is an xTR (co-located as an ITR), 1232 it next sends a data packet to the ITR (when it is an xTR co-located 1233 as an ETR), it includes the nonce received earlier with the N-bit set 1234 and E-bit cleared. The ITR sees this "echoed nonce" and knows that 1235 the path to and from the ETR is up. 1237 The ITR will set the E-bit and N-bit for every packet it sends while 1238 in the echo-nonce-request state. The time the ITR waits to process 1239 the echoed nonce before it determines the path is unreachable is 1240 variable and is a choice left for the implementation. 1242 If the ITR is receiving packets from the ETR but does not see the 1243 nonce echoed while being in the echo-nonce-request state, then the 1244 path to the ETR is unreachable. This decision MAY be overridden by 1245 other Locator reachability algorithms. Once the ITR determines that 1246 the path to the ETR is down, it can switch to another Locator for 1247 that EID-Prefix. 1249 Note that "ITR" and "ETR" are relative terms here. Both devices MUST 1250 be implementing both ITR and ETR functionality for the echo nonce 1251 mechanism to operate. 1253 The ITR and ETR MAY both go into the echo-nonce-request state at the 1254 same time. The number of packets sent or the time during which echo 1255 nonce requests are sent is an implementation-specific setting. 1256 However, when an ITR is in the echo-nonce-request state, it can echo 1257 the ETR's nonce in the next set of packets that it encapsulates and 1258 subsequently continue sending echo-nonce-request packets. 1260 This mechanism does not completely solve the forward path 1261 reachability problem, as traffic may be unidirectional. That is, the 1262 ETR receiving traffic at a site MAY not be the same device as an ITR 1263 that transmits traffic from that site, or the site-to-site traffic is 1264 unidirectional so there is no ITR returning traffic. 1266 The echo-nonce algorithm is bilateral. That is, if one side sets the 1267 E-bit and the other side is not enabled for echo-noncing, then the 1268 echoing of the nonce does not occur and the requesting side may 1269 erroneously consider the Locator unreachable. An ITR SHOULD only set 1270 the E-bit in an encapsulated data packet when it knows the ETR is 1271 enabled for echo-noncing. This is conveyed by the E-bit in the RLOC- 1272 probe Map-Reply message. 1274 11. EID Reachability within a LISP Site 1276 A site MAY be multihomed using two or more ETRs. The hosts and 1277 infrastructure within a site will be addressed using one or more EID- 1278 Prefixes that are mapped to the RLOCs of the relevant ETRs in the 1279 mapping system. One possible failure mode is for an ETR to lose 1280 reachability to one or more of the EID-Prefixes within its own site. 1281 When this occurs when the ETR sends Map-Replies, it can clear the 1282 R-bit associated with its own Locator. And when the ETR is also an 1283 ITR, it can clear its Locator-Status-Bit in the encapsulation data 1284 header. 1286 It is recognized that there are no simple solutions to the site 1287 partitioning problem because it is hard to know which part of the 1288 EID-Prefix range is partitioned and which Locators can reach any sub- 1289 ranges of the EID-Prefixes. Note that this is not a new problem 1290 introduced by the LISP architecture. The problem exists today when a 1291 multihomed site uses BGP to advertise its reachability upstream. 1293 12. Routing Locator Hashing 1295 When an ETR provides an EID-to-RLOC mapping in a Map-Reply message 1296 that is stored in the Map-Cache of a requesting ITR, the Locator-Set 1297 for the EID-Prefix MAY contain different Priority and Weight values 1298 for each locator address. When more than one best Priority Locator 1299 exists, the ITR can decide how to load-share traffic against the 1300 corresponding Locators. 1302 The following hash algorithm MAY be used by an ITR to select a 1303 Locator for a packet destined to an EID for the EID-to-RLOC mapping: 1305 1. Either a source and destination address hash or the traditional 1306 5-tuple hash can be used. The traditional 5-tuple hash includes 1307 the source and destination addresses; source and destination TCP, 1308 UDP, or Stream Control Transmission Protocol (SCTP) port numbers; 1309 and the IP protocol number field or IPv6 next-protocol fields of 1310 a packet that a host originates from within a LISP site. When a 1311 packet is not a TCP, UDP, or SCTP packet, the source and 1312 destination addresses only from the header are used to compute 1313 the hash. 1315 2. Take the hash value and divide it by the number of Locators 1316 stored in the Locator-Set for the EID-to-RLOC mapping. 1318 3. The remainder will yield a value of 0 to "number of Locators 1319 minus 1". Use the remainder to select the Locator in the 1320 Locator-Set. 1322 The specific hash algorithm the ITR uses for load-sharing is out of 1323 scope for this document and does not prevent interoperability. 1325 Note that when a packet is LISP encapsulated, the source port number 1326 in the outer UDP header needs to be set. Selecting a hashed value 1327 allows core routers that are attached to Link Aggregation Groups 1328 (LAGs) to load-split the encapsulated packets across member links of 1329 such LAGs. Otherwise, core routers would see a single flow, since 1330 packets have a source address of the ITR, for packets that are 1331 originated by different EIDs at the source site. A suggested setting 1332 for the source port number computed by an ITR is a 5-tuple hash 1333 function on the inner header, as described above. The source port 1334 SHOULD be the same for all packets belonging to the same flow. 1336 Many core router implementations use a 5-tuple hash to decide how to 1337 balance packet load across members of a LAG. The 5-tuple hash 1338 includes the source and destination addresses of the packet and the 1339 source and destination ports when the protocol number in the packet 1340 is TCP or UDP. For this reason, UDP encoding is used for LISP 1341 encapsulation. 1343 13. Changing the Contents of EID-to-RLOC Mappings 1345 Since the LISP architecture uses a caching scheme to retrieve and 1346 store EID-to-RLOC mappings, the only way an ITR can get a more up-to- 1347 date mapping is to re-request the mapping. However, the ITRs do not 1348 know when the mappings change, and the ETRs do not keep track of 1349 which ITRs requested its mappings. For scalability reasons, it is 1350 desirable to maintain this approach but need to provide a way for 1351 ETRs to change their mappings and inform the sites that are currently 1352 communicating with the ETR site using such mappings. 1354 This section defines a Data-Plane mechanism for updating EID-to-RLOC 1355 mappings. Additionally, the Solicit-Map Request (SMR) Control-Plane 1356 updating mechanism is specified in [I-D.ietf-lisp-rfc6833bis]. 1358 When adding a new Locator record in lexicographic order to the end of 1359 a Locator-Set, it is easy to update mappings. We assume that new 1360 mappings will maintain the same Locator ordering as the old mapping 1361 but will just have new Locators appended to the end of the list. So, 1362 some ITRs can have a new mapping while other ITRs have only an old 1363 mapping that is used until they time out. When an ITR has only an 1364 old mapping but detects bits set in the Locator-Status-Bits that 1365 correspond to Locators beyond the list it has cached, it simply 1366 ignores them. However, this can only happen for locator addresses 1367 that are lexicographically greater than the locator addresses in the 1368 existing Locator-Set. 1370 When a Locator record is inserted in the middle of a Locator-Set, to 1371 maintain lexicographic order, SMR procedure 1372 [I-D.ietf-lisp-rfc6833bis] is used to inform ITRs and PITRs of the 1373 new Locator-Status-Bit mappings. 1375 When a Locator record is removed from a Locator-Set, ITRs that have 1376 the mapping cached will not use the removed Locator because the xTRs 1377 will set the Locator-Status-Bit to 0. So, even if the Locator is in 1378 the list, it will not be used. For new mapping requests, the xTRs 1379 can set the Locator AFI to 0 (indicating an unspecified address), as 1380 well as setting the corresponding Locator-Status-Bit to 0. This 1381 forces ITRs with old or new mappings to avoid using the removed 1382 Locator. 1384 If many changes occur to a mapping over a long period of time, one 1385 will find empty record slots in the middle of the Locator-Set and new 1386 records appended to the Locator-Set. At some point, it would be 1387 useful to compact the Locator-Set so the Locator-Status-Bit settings 1388 can be efficiently packed. 1390 We propose here a Data-Plane mechanism (Map-Versioning specified in 1391 [I-D.ietf-lisp-6834bis]) to update the contents of EID-to-RLOC 1392 mappings. Please note that in addition the Solicit-Map Request 1393 (specified in [I-D.ietf-lisp-rfc6833bis]) is a Control-Plane 1394 mechanisms that can be used to update EID-to-RLOC mappings. 1396 13.1. Database Map-Versioning 1398 When there is unidirectional packet flow between an ITR and ETR, and 1399 the EID-to-RLOC mappings change on the ETR, it needs to inform the 1400 ITR so encapsulation to a removed Locator can stop and can instead be 1401 started to a new Locator in the Locator-Set. 1403 An ETR, when it sends Map-Reply messages, conveys its own Map-Version 1404 Number. This is known as the Destination Map-Version Number. ITRs 1405 include the Destination Map-Version Number in packets they 1406 encapsulate to the site. When an ETR decapsulates a packet and 1407 detects that the Destination Map-Version Number is less than the 1408 current version for its mapping, the SMR procedure described in 1409 [I-D.ietf-lisp-rfc6833bis] occurs. 1411 An ITR, when it encapsulates packets to ETRs, can convey its own Map- 1412 Version Number. This is known as the Source Map-Version Number. 1413 When an ETR decapsulates a packet and detects that the Source Map- 1414 Version Number is greater than the last Map-Version Number sent in a 1415 Map-Reply from the ITR's site, the ETR will send a Map-Request to one 1416 of the ETRs for the source site. 1418 A Map-Version Number is used as a sequence number per EID-Prefix, so 1419 values that are greater are considered to be more recent. A value of 1420 0 for the Source Map-Version Number or the Destination Map-Version 1421 Number conveys no versioning information, and an ITR does no 1422 comparison with previously received Map-Version Numbers. 1424 A Map-Version Number can be included in Map-Register messages as 1425 well. This is a good way for the Map-Server to assure that all ETRs 1426 for a site registering to it will be synchronized according to Map- 1427 Version Number. 1429 See [I-D.ietf-lisp-6834bis] for a more detailed analysis and 1430 description of Database Map-Versioning. 1432 14. Multicast Considerations 1434 A multicast group address, as defined in the original Internet 1435 architecture, is an identifier of a grouping of topologically 1436 independent receiver host locations. The address encoding itself 1437 does not determine the location of the receiver(s). The multicast 1438 routing protocol, and the network-based state the protocol creates, 1439 determine where the receivers are located. 1441 In the context of LISP, a multicast group address is both an EID and 1442 a Routing Locator. Therefore, no specific semantic or action needs 1443 to be taken for a destination address, as it would appear in an IP 1444 header. Therefore, a group address that appears in an inner IP 1445 header built by a source host will be used as the destination EID. 1446 The outer IP header (the destination Routing Locator address), 1447 prepended by a LISP router, can use the same group address as the 1448 destination Routing Locator, use a multicast or unicast Routing 1449 Locator obtained from a Mapping System lookup, or use other means to 1450 determine the group address mapping. 1452 With respect to the source Routing Locator address, the ITR prepends 1453 its own IP address as the source address of the outer IP header. 1454 Just like it would if the destination EID was a unicast address. 1455 This source Routing Locator address, like any other Routing Locator 1456 address, MUST be routable on the underlay. 1458 There are two approaches for LISP-Multicast, one that uses native 1459 multicast routing in the underlay with no support from the Mapping 1460 System and the other that uses only unicast routing in the underlay 1461 with support from the Mapping System. See [RFC6831] and [RFC8378], 1462 respectively, for details. Details for LISP-Multicast and 1463 interworking with non-LISP sites are described in [RFC6831] and 1464 [RFC6832]. 1466 15. Router Performance Considerations 1468 LISP is designed to be very "hardware-based forwarding friendly". A 1469 few implementation techniques can be used to incrementally implement 1470 LISP: 1472 o When a tunnel-encapsulated packet is received by an ETR, the outer 1473 destination address may not be the address of the router. This 1474 makes it challenging for the control plane to get packets from the 1475 hardware. This may be mitigated by creating special Forwarding 1476 Information Base (FIB) entries for the EID-Prefixes of EIDs served 1477 by the ETR (those for which the router provides an RLOC 1478 translation). These FIB entries are marked with a flag indicating 1479 that Control-Plane processing SHOULD be performed. The forwarding 1480 logic of testing for particular IP protocol number values is not 1481 necessary. There are a few proven cases where no changes to 1482 existing deployed hardware were needed to support the LISP Data- 1483 Plane. 1485 o On an ITR, prepending a new IP header consists of adding more 1486 octets to a MAC rewrite string and prepending the string as part 1487 of the outgoing encapsulation procedure. Routers that support 1488 Generic Routing Encapsulation (GRE) tunneling [RFC2784] or 6to4 1489 tunneling [RFC3056] may already support this action. 1491 o A packet's source address or interface the packet was received on 1492 can be used to select VRF (Virtual Routing/Forwarding). The VRF's 1493 routing table can be used to find EID-to-RLOC mappings. 1495 For performance issues related to Map-Cache management, see 1496 Section 16. 1498 16. Security Considerations 1500 A complete LISP threat analysis can be found in [RFC7835]. In what 1501 follows we highlight security considerations that apply when LISP is 1502 deployed in environments such as those specified in Section 1.1. 1504 The optional mechanisms of gleaning is offered to directly obtain a 1505 mapping from the LISP encapsulated packets. Specifically, an xTR can 1506 learn the EID-to-RLOC mapping by inspecting the source RLOC and 1507 source EID of an encapsulated packet, and insert this new mapping 1508 into its Map-Cache. An off-path attacker can spoof the source EID 1509 address to divert the traffic sent to the victim's spoofed EID. If 1510 the attacker spoofs the source RLOC, it can mount a DoS attack by 1511 redirecting traffic to the spoofed victim's RLOC, potentially 1512 overloading it. 1514 The LISP Data-Plane defines several mechanisms to monitor RLOC Data- 1515 Plane reachability, in this context Locator-Status Bits, Nonce- 1516 Present and Echo-Nonce bits of the LISP encapsulation header can be 1517 manipulated by an attacker to mount a DoS attack. An off-path 1518 attacker able to spoof the RLOC and/or nonce of a victim's xTR can 1519 manipulate such mechanisms to declare false information about the 1520 RLOC's reachability status. 1522 As an exmple of such attacks an off-path attacker can exploit the 1523 echo-nonce mechanism by sending data packets to an ITR with a random 1524 nonce from an ETR's spoofed RLOC. Note the attacker must guess a 1525 valid nonce the ITR is requesting to be echoed within a small window 1526 of time. The goal is to convince the ITR that the ETR's RLOC is 1527 reachable even when it may not be reachable. If the attack is 1528 successful, the ITR believes the wrong reachability status of the 1529 ETR's RLOC until RLOC-probing detects the correct status. This time 1530 frame is on the order of 10s of seconds. This specific attack can be 1531 mitigated by preventing RLOC spoofing in the network by deploying 1532 uRPF BCP 38 [RFC2827]. In addition and in order to exploit this 1533 vulnerability, the off-path attacker must send echo-nonce packets at 1534 high rate. If the nonces have never been requested by the ITR, it 1535 can protect itself from erroneious reachability attacks. 1537 Map-Versioning is a Data-Plane mechanism used to signal a peering xTR 1538 that a local EID-to-RLOC mapping has been updated, so that the 1539 peering xTR uses LISP Control-Plane signaling message to retrieve a 1540 fresh mapping. This can be used by an attacker to forge the map- 1541 versioning field of a LISP encapsulated header and force an excessive 1542 amount of signaling between xTRs that may overload them. 1544 Most of the attack vectors can be mitigated with careful deployment 1545 and configuration, information learned opportunistically (such as LSB 1546 or gleaning) SHOULD be verified with other reachability mechanisms. 1547 In addition, systematic rate-limitation and filtering is an effective 1548 technique to mitigate attacks that aim to overload the Control-Plane. 1550 17. Network Management Considerations 1552 Considerations for network management tools exist so the LISP 1553 protocol suite can be operationally managed. These mechanisms can be 1554 found in [RFC7052] and [RFC6835]. 1556 18. Changes since RFC 6830 1558 For implementation considerations, the following changes have been 1559 made to this document since RFC 6830 was published: 1561 o It is no longer mandated that a maximum number of 2 LISP headers 1562 be prepended to a packet. If there is a application need for more 1563 than 2 LISP headers, an implementation can support more. However, 1564 it is RECOMMENDED that a maximum of two LISP headers can be 1565 prepended to a packet. 1567 o The 3 reserved flag bits in the LISP header have been allocated 1568 for [RFC8061]. The low-order 2 bits of the 3-bit field (now named 1569 the KK bits) are used as a key identifier. The 1 remaining bit is 1570 still documented as reserved. 1572 o Data-Plane gleaning for creating map-cache entries has been made 1573 optional. Any ITR implementations that depend on or assume the 1574 remote ETR is gleaning should not do so. This does not create any 1575 interoperability problems since the control-plane map-cache 1576 population procedures are unilateral and are the typical method 1577 for map-cache population. 1579 o The bulk of the changes to this document which reduces its length 1580 are due to moving the LISP control-plane messaging and procedures 1581 to [I-D.ietf-lisp-rfc6833bis]. 1583 19. IANA Considerations 1585 This section provides guidance to the Internet Assigned Numbers 1586 Authority (IANA) regarding registration of values related to this 1587 Data-Plane LISP specification, in accordance with BCP 26 [RFC8126]. 1589 19.1. LISP UDP Port Numbers 1591 The IANA registry has allocated UDP port number 4341 for the LISP 1592 Data-Plane. IANA has updated the description for UDP port 4341 as 1593 follows: 1595 lisp-data 4341 udp LISP Data Packets 1597 20. References 1599 20.1. Normative References 1601 [I-D.ietf-lisp-6834bis] 1602 Iannone, L., Saucez, D., and O. Bonaventure, "Locator/ID 1603 Separation Protocol (LISP) Map-Versioning", draft-ietf- 1604 lisp-6834bis-02 (work in progress), September 2018. 1606 [I-D.ietf-lisp-rfc6833bis] 1607 Fuller, V., Farinacci, D., and A. Cabellos-Aparicio, 1608 "Locator/ID Separation Protocol (LISP) Control-Plane", 1609 draft-ietf-lisp-rfc6833bis-18 (work in progress), October 1610 2018. 1612 [RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768, 1613 DOI 10.17487/RFC0768, August 1980, 1614 . 1616 [RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, 1617 DOI 10.17487/RFC0791, September 1981, 1618 . 1620 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1621 Requirement Levels", BCP 14, RFC 2119, 1622 DOI 10.17487/RFC2119, March 1997, 1623 . 1625 [RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, 1626 "Definition of the Differentiated Services Field (DS 1627 Field) in the IPv4 and IPv6 Headers", RFC 2474, 1628 DOI 10.17487/RFC2474, December 1998, 1629 . 1631 [RFC2827] Ferguson, P. and D. Senie, "Network Ingress Filtering: 1632 Defeating Denial of Service Attacks which employ IP Source 1633 Address Spoofing", BCP 38, RFC 2827, DOI 10.17487/RFC2827, 1634 May 2000, . 1636 [RFC6040] Briscoe, B., "Tunnelling of Explicit Congestion 1637 Notification", RFC 6040, DOI 10.17487/RFC6040, November 1638 2010, . 1640 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 1641 Writing an IANA Considerations Section in RFCs", BCP 26, 1642 RFC 8126, DOI 10.17487/RFC8126, June 2017, 1643 . 1645 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1646 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1647 May 2017, . 1649 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 1650 (IPv6) Specification", STD 86, RFC 8200, 1651 DOI 10.17487/RFC8200, July 2017, 1652 . 1654 20.2. Informative References 1656 [AFN] IANA, "Address Family Numbers", August 2016, 1657 . 1659 [CHIAPPA] Chiappa, J., "Endpoints and Endpoint names: A Proposed", 1660 1999, 1661 . 1663 [I-D.ietf-lisp-introduction] 1664 Cabellos-Aparicio, A. and D. Saucez, "An Architectural 1665 Introduction to the Locator/ID Separation Protocol 1666 (LISP)", draft-ietf-lisp-introduction-13 (work in 1667 progress), April 2015. 1669 [I-D.ietf-lisp-vpn] 1670 Moreno, V. and D. Farinacci, "LISP Virtual Private 1671 Networks (VPNs)", draft-ietf-lisp-vpn-02 (work in 1672 progress), May 2018. 1674 [OPENLISP] 1675 Iannone, L., Saucez, D., and O. Bonaventure, "OpenLISP 1676 Implementation Report", Work in Progress, July 2008. 1678 [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", 1679 STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987, 1680 . 1682 [RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G., 1683 and E. Lear, "Address Allocation for Private Internets", 1684 BCP 5, RFC 1918, DOI 10.17487/RFC1918, February 1996, 1685 . 1687 [RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P. 1688 Traina, "Generic Routing Encapsulation (GRE)", RFC 2784, 1689 DOI 10.17487/RFC2784, March 2000, 1690 . 1692 [RFC3056] Carpenter, B. and K. Moore, "Connection of IPv6 Domains 1693 via IPv4 Clouds", RFC 3056, DOI 10.17487/RFC3056, February 1694 2001, . 1696 [RFC3232] Reynolds, J., Ed., "Assigned Numbers: RFC 1700 is Replaced 1697 by an On-line Database", RFC 3232, DOI 10.17487/RFC3232, 1698 January 2002, . 1700 [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, 1701 A., Peterson, J., Sparks, R., Handley, M., and E. 1702 Schooler, "SIP: Session Initiation Protocol", RFC 3261, 1703 DOI 10.17487/RFC3261, June 2002, 1704 . 1706 [RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker, 1707 "Randomness Requirements for Security", BCP 106, RFC 4086, 1708 DOI 10.17487/RFC4086, June 2005, 1709 . 1711 [RFC4984] Meyer, D., Ed., Zhang, L., Ed., and K. Fall, Ed., "Report 1712 from the IAB Workshop on Routing and Addressing", 1713 RFC 4984, DOI 10.17487/RFC4984, September 2007, 1714 . 1716 [RFC6831] Farinacci, D., Meyer, D., Zwiebel, J., and S. Venaas, "The 1717 Locator/ID Separation Protocol (LISP) for Multicast 1718 Environments", RFC 6831, DOI 10.17487/RFC6831, January 1719 2013, . 1721 [RFC6832] Lewis, D., Meyer, D., Farinacci, D., and V. Fuller, 1722 "Interworking between Locator/ID Separation Protocol 1723 (LISP) and Non-LISP Sites", RFC 6832, 1724 DOI 10.17487/RFC6832, January 2013, 1725 . 1727 [RFC6835] Farinacci, D. and D. Meyer, "The Locator/ID Separation 1728 Protocol Internet Groper (LIG)", RFC 6835, 1729 DOI 10.17487/RFC6835, January 2013, 1730 . 1732 [RFC6935] Eubanks, M., Chimento, P., and M. Westerlund, "IPv6 and 1733 UDP Checksums for Tunneled Packets", RFC 6935, 1734 DOI 10.17487/RFC6935, April 2013, 1735 . 1737 [RFC6936] Fairhurst, G. and M. Westerlund, "Applicability Statement 1738 for the Use of IPv6 UDP Datagrams with Zero Checksums", 1739 RFC 6936, DOI 10.17487/RFC6936, April 2013, 1740 . 1742 [RFC7052] Schudel, G., Jain, A., and V. Moreno, "Locator/ID 1743 Separation Protocol (LISP) MIB", RFC 7052, 1744 DOI 10.17487/RFC7052, October 2013, 1745 . 1747 [RFC7215] Jakab, L., Cabellos-Aparicio, A., Coras, F., Domingo- 1748 Pascual, J., and D. Lewis, "Locator/Identifier Separation 1749 Protocol (LISP) Network Element Deployment 1750 Considerations", RFC 7215, DOI 10.17487/RFC7215, April 1751 2014, . 1753 [RFC7833] Howlett, J., Hartman, S., and A. Perez-Mendez, Ed., "A 1754 RADIUS Attribute, Binding, Profiles, Name Identifier 1755 Format, and Confirmation Methods for the Security 1756 Assertion Markup Language (SAML)", RFC 7833, 1757 DOI 10.17487/RFC7833, May 2016, 1758 . 1760 [RFC7835] Saucez, D., Iannone, L., and O. Bonaventure, "Locator/ID 1761 Separation Protocol (LISP) Threat Analysis", RFC 7835, 1762 DOI 10.17487/RFC7835, April 2016, 1763 . 1765 [RFC8060] Farinacci, D., Meyer, D., and J. Snijders, "LISP Canonical 1766 Address Format (LCAF)", RFC 8060, DOI 10.17487/RFC8060, 1767 February 2017, . 1769 [RFC8061] Farinacci, D. and B. Weis, "Locator/ID Separation Protocol 1770 (LISP) Data-Plane Confidentiality", RFC 8061, 1771 DOI 10.17487/RFC8061, February 2017, 1772 . 1774 [RFC8085] Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage 1775 Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085, 1776 March 2017, . 1778 [RFC8111] Fuller, V., Lewis, D., Ermagan, V., Jain, A., and A. 1779 Smirnov, "Locator/ID Separation Protocol Delegated 1780 Database Tree (LISP-DDT)", RFC 8111, DOI 10.17487/RFC8111, 1781 May 2017, . 1783 [RFC8378] Moreno, V. and D. Farinacci, "Signal-Free Locator/ID 1784 Separation Protocol (LISP) Multicast", RFC 8378, 1785 DOI 10.17487/RFC8378, May 2018, 1786 . 1788 Appendix A. Acknowledgments 1790 An initial thank you goes to Dave Oran for planting the seeds for the 1791 initial ideas for LISP. His consultation continues to provide value 1792 to the LISP authors. 1794 A special and appreciative thank you goes to Noel Chiappa for 1795 providing architectural impetus over the past decades on separation 1796 of location and identity, as well as detailed reviews of the LISP 1797 architecture and documents, coupled with enthusiasm for making LISP a 1798 practical and incremental transition for the Internet. 1800 The original authors would like to gratefully acknowledge many people 1801 who have contributed discussions and ideas to the making of this 1802 proposal. They include Scott Brim, Andrew Partan, John Zwiebel, 1803 Jason Schiller, Lixia Zhang, Dorian Kim, Peter Schoenmaker, Vijay 1804 Gill, Geoff Huston, David Conrad, Mark Handley, Ron Bonica, Ted 1805 Seely, Mark Townsley, Chris Morrow, Brian Weis, Dave McGrew, Peter 1806 Lothberg, Dave Thaler, Eliot Lear, Shane Amante, Ved Kafle, Olivier 1807 Bonaventure, Luigi Iannone, Robin Whittle, Brian Carpenter, Joel 1808 Halpern, Terry Manderson, Roger Jorgensen, Ran Atkinson, Stig Venaas, 1809 Iljitsch van Beijnum, Roland Bless, Dana Blair, Bill Lynch, Marc 1810 Woolward, Damien Saucez, Damian Lezama, Attilla De Groot, Parantap 1811 Lahiri, David Black, Roque Gagliano, Isidor Kouvelas, Jesper Skriver, 1812 Fred Templin, Margaret Wasserman, Sam Hartman, Michael Hofling, Pedro 1813 Marques, Jari Arkko, Gregg Schudel, Srinivas Subramanian, Amit Jain, 1814 Xu Xiaohu, Dhirendra Trivedi, Yakov Rekhter, John Scudder, John 1815 Drake, Dimitri Papadimitriou, Ross Callon, Selina Heimlich, Job 1816 Snijders, Vina Ermagan, Fabio Maino, Victor Moreno, Chris White, 1817 Clarence Filsfils, Alia Atlas, Florin Coras and Alberto Rodriguez. 1819 This work originated in the Routing Research Group (RRG) of the IRTF. 1820 An individual submission was converted into the IETF LISP working 1821 group document that became this RFC. 1823 The LISP working group would like to give a special thanks to Jari 1824 Arkko, the Internet Area AD at the time that the set of LISP 1825 documents were being prepared for IESG last call, and for his 1826 meticulous reviews and detailed commentaries on the 7 working group 1827 last call documents progressing toward standards-track RFCs. 1829 The current authors would like to give a sincere thank you to the 1830 people who help put LISP on standards track in the IETF. They 1831 include Joel Halpern, Luigi Iannone, Deborah Brungard, Fabio Maino, 1832 Scott Bradner, Kyle Rose, Takeshi Takahashi, Sarah Banks, Pete 1833 Resnick, Colin Perkins, Mirja Kuhlewind, Francis Dupont, Benjamin 1834 Kaduk, Eric Rescorla, Alvaro Retana, Alexey Melnikov, Alissa Cooper, 1835 Suresh Krishnan, Alberto Rodriguez-Natal, Vina Ermagen, Mohamed 1836 Boucadair, Brian Trammell, Sabrina Tanamal, and John Drake. The 1837 contributions they offered greatly added to the security, scale, and 1838 robustness of the LISP architecture and protocols. 1840 Appendix B. Document Change Log 1842 [RFC Editor: Please delete this section on publication as RFC.] 1844 B.1. Changes to draft-ietf-lisp-rfc6830bis-24 1846 o Posted mid October 2018. 1848 o Added more to the Security Considerations section with discussion 1849 about echo-nonce attacks. 1851 B.2. Changes to draft-ietf-lisp-rfc6830bis-24 1853 o Posted mid October 2018. 1855 o Final editorial changes for Eric and Ben. 1857 B.3. Changes to draft-ietf-lisp-rfc6830bis-23 1859 o Posted early October 2018. 1861 o Added an applicability statement in section 1 to address security 1862 concerns from Telechat. 1864 B.4. Changes to draft-ietf-lisp-rfc6830bis-22 1866 o Posted early October 2018. 1868 o Changes to reflect comments post Telechat. 1870 B.5. Changes to draft-ietf-lisp-rfc6830bis-21 1872 o Posted late-September 2018. 1874 o Changes to reflect comments from Sep 27th Telechat. 1876 B.6. Changes to draft-ietf-lisp-rfc6830bis-20 1878 o Posted late-September 2018. 1880 o Fix old reference to RFC3168, changed to RFC6040. 1882 B.7. Changes to draft-ietf-lisp-rfc6830bis-19 1884 o Posted late-September 2018. 1886 o More editorial changes. 1888 B.8. Changes to draft-ietf-lisp-rfc6830bis-18 1890 o Posted mid-September 2018. 1892 o Changes to reflect comments from Secdir review (Mirja). 1894 B.9. Changes to draft-ietf-lisp-rfc6830bis-17 1896 o Posted September 2018. 1898 o Indicate in the "Changes since RFC 6830" section why the document 1899 has been shortened in length. 1901 o Make reference to RFC 8085 about UDP congestion control. 1903 o More editorial changes from multiple IESG reviews. 1905 B.10. Changes to draft-ietf-lisp-rfc6830bis-16 1907 o Posted late August 2018. 1909 o Distinguish the message type names between ICMP for IPv4 and ICMP 1910 for IPv6 for handling MTU issues. 1912 B.11. Changes to draft-ietf-lisp-rfc6830bis-15 1914 o Posted August 2018. 1916 o Final editorial changes before RFC submission for Proposed 1917 Standard. 1919 o Added section "Changes since RFC 6830" so implementers are 1920 informed of any changes since the last RFC publication. 1922 B.12. Changes to draft-ietf-lisp-rfc6830bis-14 1924 o Posted July 2018 IETF week. 1926 o Put obsolete of RFC 6830 in Intro section in addition to abstract. 1928 B.13. Changes to draft-ietf-lisp-rfc6830bis-13 1930 o Posted March IETF Week 2018. 1932 o Clarified that a new nonce is required per RLOC. 1934 o Removed 'Clock Sweep' section. This text must be placed in a new 1935 OAM document. 1937 o Some references changed from normative to informative 1939 B.14. Changes to draft-ietf-lisp-rfc6830bis-12 1941 o Posted July 2018. 1943 o Fixed Luigi editorial comments to ready draft for RFC status. 1945 B.15. Changes to draft-ietf-lisp-rfc6830bis-11 1947 o Posted March 2018. 1949 o Removed sections 16, 17 and 18 (Mobility, Deployment and 1950 Traceroute considerations). This text must be placed in a new OAM 1951 document. 1953 B.16. Changes to draft-ietf-lisp-rfc6830bis-10 1955 o Posted March 2018. 1957 o Updated section 'Router Locator Selection' stating that the Data- 1958 Plane MUST follow what's stored in the Map-Cache (priorities and 1959 weights). 1961 o Section 'Routing Locator Reachability': Removed bullet point 2 1962 (ICMP Network/Host Unreachable),3 (hints from BGP),4 (ICMP Port 1963 Unreachable),5 (receive a Map-Reply as a response) and RLOC 1964 probing 1966 o Removed 'Solicit-Map Request'. 1968 B.17. Changes to draft-ietf-lisp-rfc6830bis-09 1970 o Posted January 2018. 1972 o Add more details in section 5.3 about DSCP processing during 1973 encapsulation and decapsulation. 1975 o Added clarity to definitions in the Definition of Terms section 1976 from various commenters. 1978 o Removed PA and PI definitions from Definition of Terms section. 1980 o More editorial changes. 1982 o Removed 4342 from IANA section and move to RFC6833 IANA section. 1984 B.18. Changes to draft-ietf-lisp-rfc6830bis-08 1986 o Posted January 2018. 1988 o Remove references to research work for any protocol mechanisms. 1990 o Document scanned to make sure it is RFC 2119 compliant. 1992 o Made changes to reflect comments from document WG shepherd Luigi 1993 Iannone. 1995 o Ran IDNITs on the document. 1997 B.19. Changes to draft-ietf-lisp-rfc6830bis-07 1999 o Posted November 2017. 2001 o Rephrase how Instance-IDs are used and don't refer to [RFC1918] 2002 addresses. 2004 B.20. Changes to draft-ietf-lisp-rfc6830bis-06 2006 o Posted October 2017. 2008 o Put RTR definition before it is used. 2010 o Rename references that are now working group drafts. 2012 o Remove "EIDs MUST NOT be used as used by a host to refer to other 2013 hosts. Note that EID blocks MAY LISP RLOCs". 2015 o Indicate what address-family can appear in data packets. 2017 o ETRs may, rather than will, be the ones to send Map-Replies. 2019 o Recommend, rather than mandate, max encapsulation headers to 2. 2021 o Reference VPN draft when introducing Instance-ID. 2023 o Indicate that SMRs can be sent when ITR/ETR are in the same node. 2025 o Clarify when private addresses can be used. 2027 B.21. Changes to draft-ietf-lisp-rfc6830bis-05 2029 o Posted August 2017. 2031 o Make it clear that a Re-encapsulating Tunnel Router is an RTR. 2033 B.22. Changes to draft-ietf-lisp-rfc6830bis-04 2035 o Posted July 2017. 2037 o Changed reference of IPv6 RFC2460 to RFC8200. 2039 o Indicate that the applicability statement for UDP zero checksums 2040 over IPv6 adheres to RFC6936. 2042 B.23. Changes to draft-ietf-lisp-rfc6830bis-03 2044 o Posted May 2017. 2046 o Move the control-plane related codepoints in the IANA 2047 Considerations section to RFC6833bis. 2049 B.24. Changes to draft-ietf-lisp-rfc6830bis-02 2051 o Posted April 2017. 2053 o Reflect some editorial comments from Damien Sausez. 2055 B.25. Changes to draft-ietf-lisp-rfc6830bis-01 2057 o Posted March 2017. 2059 o Include references to new RFCs published. 2061 o Change references from RFC6833 to RFC6833bis. 2063 o Clarified LCAF text in the IANA section. 2065 o Remove references to "experimental". 2067 B.26. Changes to draft-ietf-lisp-rfc6830bis-00 2069 o Posted December 2016. 2071 o Created working group document from draft-farinacci-lisp 2072 -rfc6830-00 individual submission. No other changes made. 2074 Authors' Addresses 2076 Dino Farinacci 2077 Cisco Systems 2078 Tasman Drive 2079 San Jose, CA 95134 2080 USA 2082 EMail: farinacci@gmail.com 2084 Vince Fuller 2085 Cisco Systems 2086 Tasman Drive 2087 San Jose, CA 95134 2088 USA 2090 EMail: vince.fuller@gmail.com 2092 Dave Meyer 2093 Cisco Systems 2094 170 Tasman Drive 2095 San Jose, CA 2096 USA 2098 EMail: dmm@1-4-5.net 2100 Darrel Lewis 2101 Cisco Systems 2102 170 Tasman Drive 2103 San Jose, CA 2104 USA 2106 EMail: darlewis@cisco.com 2107 Albert Cabellos 2108 UPC/BarcelonaTech 2109 Campus Nord, C. Jordi Girona 1-3 2110 Barcelona, Catalunya 2111 Spain 2113 EMail: acabello@ac.upc.edu