idnits 2.17.1 draft-ietf-lisp-rfc6830bis-24.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 12, 2018) is 2021 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in RFCs) == Unused Reference: 'RFC7833' is defined on line 1728, but no explicit reference was found in the text == Outdated reference: A later version (-14) exists of draft-ietf-lisp-6834bis-02 == Outdated reference: A later version (-31) exists of draft-ietf-lisp-rfc6833bis-17 == Outdated reference: A later version (-15) exists of draft-ietf-lisp-introduction-13 == Outdated reference: A later version (-12) exists of draft-ietf-lisp-vpn-02 Summary: 0 errors (**), 0 flaws (~~), 6 warnings (==), 1 comment (--).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 15, 2019 Cisco Systems 7 A. Cabellos (Ed.) 8 UPC/BarcelonaTech 9 October 12, 2018 11 The Locator/ID Separation Protocol (LISP) 12 draft-ietf-lisp-rfc6830bis-24 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 15, 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-23 . . . . . . . . 40 100 B.3. Changes to draft-ietf-lisp-rfc6830bis-22 . . . . . . . . 40 101 B.4. Changes to draft-ietf-lisp-rfc6830bis-21 . . . . . . . . 40 102 B.5. Changes to draft-ietf-lisp-rfc6830bis-20 . . . . . . . . 40 103 B.6. Changes to draft-ietf-lisp-rfc6830bis-19 . . . . . . . . 40 104 B.7. Changes to draft-ietf-lisp-rfc6830bis-18 . . . . . . . . 41 105 B.8. Changes to draft-ietf-lisp-rfc6830bis-17 . . . . . . . . 41 106 B.9. Changes to draft-ietf-lisp-rfc6830bis-16 . . . . . . . . 41 107 B.10. Changes to draft-ietf-lisp-rfc6830bis-15 . . . . . . . . 41 108 B.11. Changes to draft-ietf-lisp-rfc6830bis-14 . . . . . . . . 41 109 B.12. Changes to draft-ietf-lisp-rfc6830bis-13 . . . . . . . . 41 110 B.13. Changes to draft-ietf-lisp-rfc6830bis-12 . . . . . . . . 42 111 B.14. Changes to draft-ietf-lisp-rfc6830bis-11 . . . . . . . . 42 112 B.15. Changes to draft-ietf-lisp-rfc6830bis-10 . . . . . . . . 42 113 B.16. Changes to draft-ietf-lisp-rfc6830bis-09 . . . . . . . . 42 114 B.17. Changes to draft-ietf-lisp-rfc6830bis-08 . . . . . . . . 43 115 B.18. Changes to draft-ietf-lisp-rfc6830bis-07 . . . . . . . . 43 116 B.19. Changes to draft-ietf-lisp-rfc6830bis-06 . . . . . . . . 43 117 B.20. Changes to draft-ietf-lisp-rfc6830bis-05 . . . . . . . . 43 118 B.21. Changes to draft-ietf-lisp-rfc6830bis-04 . . . . . . . . 44 119 B.22. Changes to draft-ietf-lisp-rfc6830bis-03 . . . . . . . . 44 120 B.23. Changes to draft-ietf-lisp-rfc6830bis-02 . . . . . . . . 44 121 B.24. Changes to draft-ietf-lisp-rfc6830bis-01 . . . . . . . . 44 122 B.25. Changes to draft-ietf-lisp-rfc6830bis-00 . . . . . . . . 44 123 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 44 125 1. Introduction 127 This document describes the Locator/Identifier Separation Protocol 128 (LISP). LISP is an encapsulation protocol built around the 129 fundamental idea of separating the topological location of a network 130 attachment point from the node's identity [CHIAPPA]. As a result 131 LISP creates two namespaces: Endpoint Identifiers (EIDs), that are 132 used to identify end-hosts (e.g., nodes or Virtual Machines) and 133 routable Routing Locators (RLOCs), used to identify network 134 attachment points. LISP then defines functions for mapping between 135 the two namespaces and for encapsulating traffic originated by 136 devices using non-routable EIDs for transport across a network 137 infrastructure that routes and forwards using RLOCs. LISP 138 encapsulation uses a dynamic form of tunneling where no static 139 provisioning is required or necessary. 141 LISP is an overlay protocol that separates control from Data-Plane, 142 this document specifies the Data-Plane, how LISP-capable routers 143 (Tunnel Routers) exchange packets by encapsulating them to the 144 appropriate location. Tunnel routers are equipped with a cache, 145 called Map-Cache, that contains EID-to-RLOC mappings. The Map-Cache 146 is populated using the LISP Control-Plane protocol 147 [I-D.ietf-lisp-rfc6833bis]. 149 LISP does not require changes to either host protocol stack or to 150 underlay routers. By separating the EID from the RLOC space, LISP 151 offers native Traffic Engineering, multihoming and mobility, among 152 other features. 154 Creation of LISP was initially motivated by discussions during the 155 IAB-sponsored Routing and Addressing Workshop held in Amsterdam in 156 October 2006 (see [RFC4984]). 158 This document specifies the LISP Data-Plane encapsulation and other 159 LISP forwarding node functionality while [I-D.ietf-lisp-rfc6833bis] 160 specifies the LISP control plane. LISP deployment guidelines can be 161 found in [RFC7215] and [RFC6835] describes considerations for network 162 operational management. Finally, [I-D.ietf-lisp-introduction] 163 describes the LISP architecture. 165 This document obsoletes RFC 6830. 167 1.1. Scope of Applicability 169 LISP was originally developed to address the Internet-wide route 170 scaling problem [RFC4984]. While there are a number of approaches of 171 interest for that problem, as LISP as been developed and refined, a 172 large number of other LISP uses have been found and are being used. 173 As such, the design and development of LISP has changed so as to 174 focus on these use cases. The common property of these uses is a 175 large set of cooperating entities seeking to communicate over the 176 public Internet or other large underlay IP infrastructures, while 177 keeping the addressing and topology of the cooperating entities 178 separate from the underlay and Internet topology, routing, and 179 addressing. 181 2. Requirements Notation 183 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 184 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 185 "OPTIONAL" in this document are to be interpreted as described in BCP 186 14 [RFC2119] [RFC8174] when, and only when, they appear in all 187 capitals, as shown here. 189 3. Definition of Terms 191 Address Family Identifier (AFI): AFI is a term used to describe an 192 address encoding in a packet. An address family that pertains to 193 addresses found in Data-Plane headers. See [AFN] and [RFC3232] 194 for details. An AFI value of 0 used in this specification 195 indicates an unspecified encoded address where the length of the 196 address is 0 octets following the 16-bit AFI value of 0. 198 Anycast Address: Anycast Address is a term used in this document to 199 refer to the same IPv4 or IPv6 address configured and used on 200 multiple systems at the same time. An EID or RLOC can be an 201 anycast address in each of their own address spaces. 203 Client-side: Client-side is a term used in this document to indicate 204 a connection initiation attempt by an end-system represented by an 205 EID. 207 Data-Probe: A Data-Probe is a LISP-encapsulated data packet where 208 the inner-header destination address equals the outer-header 209 destination address used to trigger a Map-Reply by a decapsulating 210 ETR. In addition, the original packet is decapsulated and 211 delivered to the destination host if the destination EID is in the 212 EID-Prefix range configured on the ETR. Otherwise, the packet is 213 discarded. A Data-Probe is used in some of the mapping database 214 designs to "probe" or request a Map-Reply from an ETR; in other 215 cases, Map-Requests are used. See each mapping database design 216 for details. When using Data-Probes, by sending Map-Requests on 217 the underlying routing system, EID-Prefixes must be advertised. 219 Egress Tunnel Router (ETR): An ETR is a router that accepts an IP 220 packet where the destination address in the "outer" IP header is 221 one of its own RLOCs. The router strips the "outer" header and 222 forwards the packet based on the next IP header found. In 223 general, an ETR receives LISP-encapsulated IP packets from the 224 Internet on one side and sends decapsulated IP packets to site 225 end-systems on the other side. ETR functionality does not have to 226 be limited to a router device. A server host can be the endpoint 227 of a LISP tunnel as well. 229 EID-to-RLOC Database: The EID-to-RLOC Database is a global 230 distributed database that contains all known EID-Prefix-to-RLOC 231 mappings. Each potential ETR typically contains a small piece of 232 the database: the EID-to-RLOC mappings for the EID-Prefixes 233 "behind" the router. These map to one of the router's own IP 234 addresses that are routable on the underlay. Note that there MAY 235 be transient conditions when the EID-Prefix for the site and 236 Locator-Set for each EID-Prefix may not be the same on all ETRs. 238 This has no negative implications, since a partial set of Locators 239 can be used. 241 EID-to-RLOC Map-Cache: The EID-to-RLOC Map-Cache is generally 242 short-lived, on-demand table in an ITR that stores, tracks, and is 243 responsible for timing out and otherwise validating EID-to-RLOC 244 mappings. This cache is distinct from the full "database" of EID- 245 to-RLOC mappings; it is dynamic, local to the ITR(s), and 246 relatively small, while the database is distributed, relatively 247 static, and much more global in scope to LISP nodes. 249 EID-Prefix: An EID-Prefix is a power-of-two block of EIDs that are 250 allocated to a site by an address allocation authority. EID- 251 Prefixes are associated with a set of RLOC addresses. EID-Prefix 252 allocations can be broken up into smaller blocks when an RLOC set 253 is to be associated with the larger EID-Prefix block. 255 End-System: An end-system is an IPv4 or IPv6 device that originates 256 packets with a single IPv4 or IPv6 header. The end-system 257 supplies an EID value for the destination address field of the IP 258 header when communicating outside of its routing domain. An end- 259 system can be a host computer, a switch or router device, or any 260 network appliance. 262 Endpoint ID (EID): An EID is a 32-bit (for IPv4) or 128-bit (for 263 IPv6) value used in the source and destination address fields of 264 the first (most inner) LISP header of a packet. The host obtains 265 a destination EID the same way it obtains a destination address 266 today, for example, through a Domain Name System (DNS) [RFC1034] 267 lookup or Session Initiation Protocol (SIP) [RFC3261] exchange. 268 The source EID is obtained via existing mechanisms used to set a 269 host's "local" IP address. An EID used on the public Internet 270 MUST have the same properties as any other IP address used in that 271 manner; this means, among other things, that it MUST be globally 272 unique. An EID is allocated to a host from an EID-Prefix block 273 associated with the site where the host is located. An EID can be 274 used by a host to refer to other hosts. Note that EID blocks MAY 275 be assigned in a hierarchical manner, independent of the network 276 topology, to facilitate scaling of the mapping database. In 277 addition, an EID block assigned to a site MAY have site-local 278 structure (subnetting) for routing within the site; this structure 279 is not visible to the underlay routing system. In theory, the bit 280 string that represents an EID for one device can represent an RLOC 281 for a different device. When used in discussions with other 282 Locator/ID separation proposals, a LISP EID will be called an 283 "LEID". Throughout this document, any references to "EID" refer 284 to an LEID. 286 Ingress Tunnel Router (ITR): An ITR is a router that resides in a 287 LISP site. Packets sent by sources inside of the LISP site to 288 destinations outside of the site are candidates for encapsulation 289 by the ITR. The ITR treats the IP destination address as an EID 290 and performs an EID-to-RLOC mapping lookup. The router then 291 prepends an "outer" IP header with one of its routable RLOCs (in 292 the RLOC space) in the source address field and the result of the 293 mapping lookup in the destination address field. Note that this 294 destination RLOC may be an intermediate, proxy device that has 295 better knowledge of the EID-to-RLOC mapping closer to the 296 destination EID. In general, an ITR receives IP packets from site 297 end-systems on one side and sends LISP-encapsulated IP packets 298 toward the Internet on the other side. 300 Specifically, when a service provider prepends a LISP header for 301 Traffic Engineering purposes, the router that does this is also 302 regarded as an ITR. The outer RLOC the ISP ITR uses can be based 303 on the outer destination address (the originating ITR's supplied 304 RLOC) or the inner destination address (the originating host's 305 supplied EID). 307 LISP Header: LISP header is a term used in this document to refer 308 to the outer IPv4 or IPv6 header, a UDP header, and a LISP- 309 specific 8-octet header that follow the UDP header and that an ITR 310 prepends or an ETR strips. 312 LISP Router: A LISP router is a router that performs the functions 313 of any or all of the following: ITR, ETR, RTR, Proxy-ITR (PITR), 314 or Proxy-ETR (PETR). 316 LISP Site: LISP site is a set of routers in an edge network that are 317 under a single technical administration. LISP routers that reside 318 in the edge network are the demarcation points to separate the 319 edge network from the core network. 321 Locator-Status-Bits (LSBs): Locator-Status-Bits are present in the 322 LISP header. They are used by ITRs to inform ETRs about the up/ 323 down status of all ETRs at the local site. These bits are used as 324 a hint to convey up/down router status and not path reachability 325 status. The LSBs can be verified by use of one of the Locator 326 reachability algorithms described in Section 10. An ETR MUST 327 rate-limit the action it takes when it detects changes in the 328 Locator-Status-Bits. 330 Negative Mapping Entry: A negative mapping entry, also known as a 331 negative cache entry, is an EID-to-RLOC entry where an EID-Prefix 332 is advertised or stored with no RLOCs. That is, the Locator-Set 333 for the EID-to-RLOC entry is empty, one with an encoded Locator 334 count of 0. This type of entry could be used to describe a prefix 335 from a non-LISP site, which is explicitly not in the mapping 336 database. There are a set of well-defined actions that are 337 encoded in a Negative Map-Reply. 339 Proxy-ETR (PETR): A PETR is defined and described in [RFC6832]. A 340 PETR acts like an ETR but does so on behalf of LISP sites that 341 send packets to destinations at non-LISP sites. 343 Proxy-ITR (PITR): A PITR is defined and described in [RFC6832]. A 344 PITR acts like an ITR but does so on behalf of non-LISP sites that 345 send packets to destinations at LISP sites. 347 Recursive Tunneling: Recursive Tunneling occurs when a packet has 348 more than one LISP IP header. Additional layers of tunneling MAY 349 be employed to implement Traffic Engineering or other re-routing 350 as needed. When this is done, an additional "outer" LISP header 351 is added, and the original RLOCs are preserved in the "inner" 352 header. 354 Re-Encapsulating Tunneling Router (RTR): An RTR acts like an ETR to 355 remove a LISP header, then acts as an ITR to prepend a new LISP 356 header. This is known as Re-encapsulating Tunneling. Doing this 357 allows a packet to be re-routed by the RTR without adding the 358 overhead of additional tunnel headers. When using multiple 359 mapping database systems, care must be taken to not create re- 360 encapsulation loops through misconfiguration. 362 Route-Returnability: Route-returnability is an assumption that the 363 underlying routing system will deliver packets to the destination. 364 When combined with a nonce that is provided by a sender and 365 returned by a receiver, this limits off-path data insertion. A 366 route-returnability check is verified when a message is sent with 367 a nonce, another message is returned with the same nonce, and the 368 destination of the original message appears as the source of the 369 returned message. 371 Routing Locator (RLOC): An RLOC is an IPv4 [RFC0791] or IPv6 372 [RFC8200] address of an Egress Tunnel Router (ETR). An RLOC is 373 the output of an EID-to-RLOC mapping lookup. An EID maps to zero 374 or more RLOCs. Typically, RLOCs are numbered from blocks that are 375 assigned to a site at each point to which it attaches to the 376 underlay network; where the topology is defined by the 377 connectivity of provider networks. Multiple RLOCs can be assigned 378 to the same ETR device or to multiple ETR devices at a site. 380 Server-side: Server-side is a term used in this document to indicate 381 that a connection initiation attempt is being accepted for a 382 destination EID. 384 TE-ETR: A TE-ETR is an ETR that is deployed in a service provider 385 network that strips an outer LISP header for Traffic Engineering 386 purposes. 388 TE-ITR: A TE-ITR is an ITR that is deployed in a service provider 389 network that prepends an additional LISP header for Traffic 390 Engineering purposes. 392 xTR: An xTR is a reference to an ITR or ETR when direction of data 393 flow is not part of the context description. "xTR" refers to the 394 router that is the tunnel endpoint and is used synonymously with 395 the term "Tunnel Router". For example, "An xTR can be located at 396 the Customer Edge (CE) router" indicates both ITR and ETR 397 functionality at the CE router. 399 4. Basic Overview 401 One key concept of LISP is that end-systems operate the same way they 402 do today. The IP addresses that hosts use for tracking sockets and 403 connections, and for sending and receiving packets, do not change. 404 In LISP terminology, these IP addresses are called Endpoint 405 Identifiers (EIDs). 407 Routers continue to forward packets based on IP destination 408 addresses. When a packet is LISP encapsulated, these addresses are 409 referred to as Routing Locators (RLOCs). Most routers along a path 410 between two hosts will not change; they continue to perform routing/ 411 forwarding lookups on the destination addresses. For routers between 412 the source host and the ITR as well as routers from the ETR to the 413 destination host, the destination address is an EID. For the routers 414 between the ITR and the ETR, the destination address is an RLOC. 416 Another key LISP concept is the "Tunnel Router". A Tunnel Router 417 prepends LISP headers on host-originated packets and strips them 418 prior to final delivery to their destination. The IP addresses in 419 this "outer header" are RLOCs. During end-to-end packet exchange 420 between two Internet hosts, an ITR prepends a new LISP header to each 421 packet, and an ETR strips the new header. The ITR performs EID-to- 422 RLOC lookups to determine the routing path to the ETR, which has the 423 RLOC as one of its IP addresses. 425 Some basic rules governing LISP are: 427 o End-systems only send to addresses that are EIDs. EIDs are 428 typically IP addresses assigned to hosts (other types of EID are 429 supported by LISP, see [RFC8060] for further information). End- 430 systems don't know that addresses are EIDs versus RLOCs but assume 431 that packets get to their intended destinations. In a system 432 where LISP is deployed, LISP routers intercept EID-addressed 433 packets and assist in delivering them across the network core 434 where EIDs cannot be routed. The procedure a host uses to send IP 435 packets does not change. 437 o LISP routers mostly deal with Routing Locator addresses. See 438 details in Section 4.1 to clarify what is meant by "mostly". 440 o RLOCs are always IP addresses assigned to routers, preferably 441 topologically oriented addresses from provider CIDR (Classless 442 Inter-Domain Routing) blocks. 444 o When a router originates packets, it MAY use as a source address 445 either an EID or RLOC. When acting as a host (e.g., when 446 terminating a transport session such as Secure SHell (SSH), 447 TELNET, or the Simple Network Management Protocol (SNMP)), it MAY 448 use an EID that is explicitly assigned for that purpose. An EID 449 that identifies the router as a host MUST NOT be used as an RLOC; 450 an EID is only routable within the scope of a site. A typical BGP 451 configuration might demonstrate this "hybrid" EID/RLOC usage where 452 a router could use its "host-like" EID to terminate iBGP sessions 453 to other routers in a site while at the same time using RLOCs to 454 terminate eBGP sessions to routers outside the site. 456 o Packets with EIDs in them are not expected to be delivered end-to- 457 end in the absence of an EID-to-RLOC mapping operation. They are 458 expected to be used locally for intra-site communication or to be 459 encapsulated for inter-site communication. 461 o EIDs MAY also be structured (subnetted) in a manner suitable for 462 local routing within an Autonomous System (AS). 464 An additional LISP header MAY be prepended to packets by a TE-ITR 465 when re-routing of the path for a packet is desired. A potential 466 use-case for this would be an ISP router that needs to perform 467 Traffic Engineering for packets flowing through its network. In such 468 a situation, termed "Recursive Tunneling", an ISP transit acts as an 469 additional ITR, and the destination RLOC it uses for the new 470 prepended header would be either a TE-ETR within the ISP (along an 471 intra-ISP traffic engineered path) or a TE-ETR within another ISP (an 472 inter-ISP traffic engineered path, where an agreement to build such a 473 path exists). 475 In order to avoid excessive packet overhead as well as possible 476 encapsulation loops, this document recommends that a maximum of two 477 LISP headers can be prepended to a packet. For initial LISP 478 deployments, it is assumed that two headers is sufficient, where the 479 first prepended header is used at a site for Location/Identity 480 separation and the second prepended header is used inside a service 481 provider for Traffic Engineering purposes. 483 Tunnel Routers can be placed fairly flexibly in a multi-AS topology. 484 For example, the ITR for a particular end-to-end packet exchange 485 might be the first-hop or default router within a site for the source 486 host. Similarly, the ETR might be the last-hop router directly 487 connected to the destination host. Another example, perhaps for a 488 VPN service outsourced to an ISP by a site, the ITR could be the 489 site's border router at the service provider attachment point. 490 Mixing and matching of site-operated, ISP-operated, and other Tunnel 491 Routers is allowed for maximum flexibility. 493 4.1. Packet Flow Sequence 495 This section provides an example of the unicast packet flow, 496 including also Control-Plane information as specified in 497 [I-D.ietf-lisp-rfc6833bis]. The example also assumes the following 498 conditions: 500 o Source host "host1.abc.example.com" is sending a packet to 501 "host2.xyz.example.com", exactly what host1 would do if the site 502 was not using LISP. 504 o Each site is multihomed, so each Tunnel Router has an address 505 (RLOC) assigned from the service provider address block for each 506 provider to which that particular Tunnel Router is attached. 508 o The ITR(s) and ETR(s) are directly connected to the source and 509 destination, respectively, but the source and destination can be 510 located anywhere in the LISP site. 512 o A Map-Request is sent for an external destination when the 513 destination is not found in the forwarding table or matches a 514 default route. Map-Requests are sent to the mapping database 515 system by using the LISP Control-Plane protocol documented in 516 [I-D.ietf-lisp-rfc6833bis]. 518 o Map-Replies are sent on the underlying routing system topology 519 using the [I-D.ietf-lisp-rfc6833bis] Control-Plane protocol. 521 Client host1.abc.example.com wants to communicate with server 522 host2.xyz.example.com: 524 1. host1.abc.example.com wants to open a TCP connection to 525 host2.xyz.example.com. It does a DNS lookup on 526 host2.xyz.example.com. An A/AAAA record is returned. This 527 address is the destination EID. The locally assigned address of 528 host1.abc.example.com is used as the source EID. An IPv4 or IPv6 529 packet is built and forwarded through the LISP site as a normal 530 IP packet until it reaches a LISP ITR. 532 2. The LISP ITR must be able to map the destination EID to an RLOC 533 of one of the ETRs at the destination site. The specific method 534 used to do this is not described in this example. See 535 [I-D.ietf-lisp-rfc6833bis] for further information. 537 3. The ITR sends a LISP Map-Request as specified in 538 [I-D.ietf-lisp-rfc6833bis]. Map-Requests SHOULD be rate-limited. 540 4. The mapping system helps forwarding the Map-Request to the 541 corresponding ETR. When the Map-Request arrives at one of the 542 ETRs at the destination site, it will process the packet as a 543 control message. 545 5. The ETR looks at the destination EID of the Map-Request and 546 matches it against the prefixes in the ETR's configured EID-to- 547 RLOC mapping database. This is the list of EID-Prefixes the ETR 548 is supporting for the site it resides in. If there is no match, 549 the Map-Request is dropped. Otherwise, a LISP Map-Reply is 550 returned to the ITR. 552 6. The ITR receives the Map-Reply message, parses the message (to 553 check for format validity), and stores the mapping information 554 from the packet. This information is stored in the ITR's EID-to- 555 RLOC Map-Cache. Note that the Map-Cache is an on-demand cache. 556 An ITR will manage its Map-Cache in such a way that optimizes for 557 its resource constraints. 559 7. Subsequent packets from host1.abc.example.com to 560 host2.xyz.example.com will have a LISP header prepended by the 561 ITR using the appropriate RLOC as the LISP header destination 562 address learned from the ETR. Note that the packet MAY be sent 563 to a different ETR than the one that returned the Map-Reply due 564 to the source site's hashing policy or the destination site's 565 Locator-Set policy. 567 8. The ETR receives these packets directly (since the destination 568 address is one of its assigned IP addresses), checks the validity 569 of the addresses, strips the LISP header, and forwards packets to 570 the attached destination host. 572 9. In order to defer the need for a mapping lookup in the reverse 573 direction, an ETR can OPTIONALLY create a cache entry that maps 574 the source EID (inner-header source IP address) to the source 575 RLOC (outer-header source IP address) in a received LISP packet. 576 Such a cache entry is termed a "glean mapping" and only contains 577 a single RLOC for the EID in question. More complete information 578 about additional RLOCs SHOULD be verified by sending a LISP Map- 579 Request for that EID. Both the ITR and the ETR MAY also 580 influence the decision the other makes in selecting an RLOC. 582 5. LISP Encapsulation Details 584 Since additional tunnel headers are prepended, the packet becomes 585 larger and can exceed the MTU of any link traversed from the ITR to 586 the ETR. It is RECOMMENDED in IPv4 that packets do not get 587 fragmented as they are encapsulated by the ITR. Instead, the packet 588 is dropped and an ICMP Unreachable/Fragmentation-Needed message is 589 returned to the source. 591 In the case when fragmentation is needed, this specification 592 RECOMMENDS that implementations provide support for one of the 593 proposed fragmentation and reassembly schemes. Two existing schemes 594 are detailed in Section 7. 596 Since IPv4 or IPv6 addresses can be either EIDs or RLOCs, the LISP 597 architecture supports IPv4 EIDs with IPv6 RLOCs (where the inner 598 header is in IPv4 packet format and the outer header is in IPv6 599 packet format) or IPv6 EIDs with IPv4 RLOCs (where the inner header 600 is in IPv6 packet format and the outer header is in IPv4 packet 601 format). The next sub-sections illustrate packet formats for the 602 homogeneous case (IPv4-in-IPv4 and IPv6-in-IPv6), but all 4 603 combinations MUST be supported. Additional types of EIDs are defined 604 in [RFC8060]. 606 As LISP uses UDP encapsulation to carry traffic between xTRs across 607 the Internet, implementors should be aware of the provisions of 608 [RFC8085], especially those given in section 3.1.11 on congestion 609 control for UDP tunneling. 611 Implementors are encouraged to consider UDP checksum usage guidelines 612 in section 3.4 of [RFC8085] when it is desirable to protect UDP and 613 LISP headers against corruption. 615 5.1. LISP IPv4-in-IPv4 Header Format 616 0 1 2 3 617 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 1 618 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 619 / |Version| IHL | DSCP |ECN| Total Length | 620 / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 621 | | Identification |Flags| Fragment Offset | 622 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 623 OH | Time to Live | Protocol = 17 | Header Checksum | 624 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 625 | | Source Routing Locator | 626 \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 627 \ | Destination Routing Locator | 628 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 629 / | Source Port = xxxx | Dest Port = 4341 | 630 UDP +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 631 \ | UDP Length | UDP Checksum | 632 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 633 L |N|L|E|V|I|R|K|K| Nonce/Map-Version | 634 I \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 635 S / | Instance ID/Locator-Status-Bits | 636 P +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 637 / |Version| IHL | DSCP |ECN| Total Length | 638 / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 639 | | Identification |Flags| Fragment Offset | 640 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 641 IH | Time to Live | Protocol | Header Checksum | 642 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 643 | | Source EID | 644 \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 645 \ | Destination EID | 646 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 648 IHL = IP-Header-Length 650 5.2. LISP IPv6-in-IPv6 Header Format 652 0 1 2 3 653 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 1 654 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 655 / |Version| DSCP |ECN| Flow Label | 656 / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 657 | | Payload Length | Next Header=17| Hop Limit | 658 v +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 659 | | 660 O + + 661 u | | 662 t + Source Routing Locator + 663 e | | 664 r + + 665 | | 666 H +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 667 d | | 668 r + + 669 | | 670 ^ + Destination Routing Locator + 671 | | | 672 \ + + 673 \ | | 674 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 675 / | Source Port = xxxx | Dest Port = 4341 | 676 UDP +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 677 \ | UDP Length | UDP Checksum | 678 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 679 L |N|L|E|V|I|R|K|K| Nonce/Map-Version | 680 I \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 681 S / | Instance ID/Locator-Status-Bits | 682 P +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 683 / |Version| DSCP |ECN| Flow Label | 684 / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 685 / | Payload Length | Next Header | Hop Limit | 686 v +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 687 | | 688 I + + 689 n | | 690 n + Source EID + 691 e | | 692 r + + 693 | | 694 H +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 695 d | | 696 r + + 697 | | 698 ^ + Destination EID + 699 \ | | 700 \ + + 701 \ | | 702 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 704 5.3. Tunnel Header Field Descriptions 706 Inner Header (IH): The inner header is the header on the 707 datagram received from the originating host [RFC0791] [RFC8200] 708 [RFC2474]. The source and destination IP addresses are EIDs. 710 Outer Header: (OH) The outer header is a new header prepended by an 711 ITR. The address fields contain RLOCs obtained from the ingress 712 router's EID-to-RLOC Cache. The IP protocol number is "UDP (17)" 713 from [RFC0768]. The setting of the Don't Fragment (DF) bit 714 'Flags' field is according to rules listed in Sections 7.1 and 715 7.2. 717 UDP Header: The UDP header contains an ITR selected source port when 718 encapsulating a packet. See Section 12 for details on the hash 719 algorithm used to select a source port based on the 5-tuple of the 720 inner header. The destination port MUST be set to the well-known 721 IANA-assigned port value 4341. 723 UDP Checksum: The 'UDP Checksum' field SHOULD be transmitted as zero 724 by an ITR for either IPv4 [RFC0768] and IPv6 encapsulation 725 [RFC6935] [RFC6936]. When a packet with a zero UDP checksum is 726 received by an ETR, the ETR MUST accept the packet for 727 decapsulation. When an ITR transmits a non-zero value for the UDP 728 checksum, it MUST send a correctly computed value in this field. 729 When an ETR receives a packet with a non-zero UDP checksum, it MAY 730 choose to verify the checksum value. If it chooses to perform 731 such verification, and the verification fails, the packet MUST be 732 silently dropped. If the ETR chooses not to perform the 733 verification, or performs the verification successfully, the 734 packet MUST be accepted for decapsulation. The handling of UDP 735 zero checksums over IPv6 for all tunneling protocols, including 736 LISP, is subject to the applicability statement in [RFC6936]. 738 UDP Length: The 'UDP Length' field is set for an IPv4-encapsulated 739 packet to be the sum of the inner-header IPv4 Total Length plus 740 the UDP and LISP header lengths. For an IPv6-encapsulated packet, 741 the 'UDP Length' field is the sum of the inner-header IPv6 Payload 742 Length, the size of the IPv6 header (40 octets), and the size of 743 the UDP and LISP headers. 745 N: The N-bit is the nonce-present bit. When this bit is set to 1, 746 the low-order 24 bits of the first 32 bits of the LISP header 747 contain a Nonce. See Section 10.1 for details. Both N- and 748 V-bits MUST NOT be set in the same packet. If they are, a 749 decapsulating ETR MUST treat the 'Nonce/Map-Version' field as 750 having a Nonce value present. 752 L: The L-bit is the 'Locator-Status-Bits' field enabled bit. When 753 this bit is set to 1, the Locator-Status-Bits in the second 754 32 bits of the LISP header are in use. 756 x 1 x x 0 x x x 757 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 758 |N|L|E|V|I|R|K|K| Nonce/Map-Version | 759 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 760 | Locator-Status-Bits | 761 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 763 E: The E-bit is the echo-nonce-request bit. This bit MUST be ignored 764 and has no meaning when the N-bit is set to 0. When the N-bit is 765 set to 1 and this bit is set to 1, an ITR is requesting that the 766 nonce value in the 'Nonce' field be echoed back in LISP- 767 encapsulated packets when the ITR is also an ETR. See 768 Section 10.1 for details. 770 V: The V-bit is the Map-Version present bit. When this bit is set to 771 1, the N-bit MUST be 0. Refer to Section 13.1 for more details. 772 This bit indicates that the LISP header is encoded in this 773 case as: 775 0 x 0 1 x x x x 776 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 777 |N|L|E|V|I|R|K|K| Source Map-Version | Dest Map-Version | 778 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 779 | Instance ID/Locator-Status-Bits | 780 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 782 I: The I-bit is the Instance ID bit. See Section 8 for more details. 783 When this bit is set to 1, the 'Locator-Status-Bits' field is 784 reduced to 8 bits and the high-order 24 bits are used as an 785 Instance ID. If the L-bit is set to 0, then the low-order 8 bits 786 are transmitted as zero and ignored on receipt. The format of the 787 LISP header would look like this: 789 x x x x 1 x x x 790 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 791 |N|L|E|V|I|R|K|K| Nonce/Map-Version | 792 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 793 | Instance ID | LSBs | 794 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 796 R: The R-bit is a Reserved bit for future use. It MUST be set to 0 797 on transmit and MUST be ignored on receipt. 799 KK: The KK-bits are a 2-bit field used when encapsulated packets are 800 encrypted. The field is set to 00 when the packet is not 801 encrypted. See [RFC8061] for further information. 803 LISP Nonce: The LISP 'Nonce' field is a 24-bit value that is 804 randomly generated by an ITR when the N-bit is set to 1. Nonce 805 generation algorithms are an implementation matter but are 806 required to generate different nonces when sending to different 807 RLOCs. However, the same nonce can be used for a period of time 808 when encapsulating to the same ETR. The nonce is also used when 809 the E-bit is set to request the nonce value to be echoed by the 810 other side when packets are returned. When the E-bit is clear but 811 the N-bit is set, a remote ITR is either echoing a previously 812 requested echo-nonce or providing a random nonce. See 813 Section 10.1 for more details. 815 LISP Locator-Status-Bits (LSBs): When the L-bit is also set, the 816 'Locator-Status-Bits' field in the LISP header is set by an ITR to 817 indicate to an ETR the up/down status of the Locators in the 818 source site. Each RLOC in a Map-Reply is assigned an ordinal 819 value from 0 to n-1 (when there are n RLOCs in a mapping entry). 820 The Locator-Status-Bits are numbered from 0 to n-1 from the least 821 significant bit of the field. The field is 32 bits when the I-bit 822 is set to 0 and is 8 bits when the I-bit is set to 1. When a 823 Locator-Status-Bit is set to 1, the ITR is indicating to the ETR 824 that the RLOC associated with the bit ordinal has up status. See 825 Section 10 for details on how an ITR can determine the status of 826 the ETRs at the same site. When a site has multiple EID-Prefixes 827 that result in multiple mappings (where each could have a 828 different Locator-Set), the Locator-Status-Bits setting in an 829 encapsulated packet MUST reflect the mapping for the EID-Prefix 830 that the inner-header source EID address matches. If the LSB for 831 an anycast Locator is set to 1, then there is at least one RLOC 832 with that address, and the ETR is considered 'up'. 834 When doing ITR/PITR encapsulation: 836 o The outer-header 'Time to Live' field (or 'Hop Limit' field, in 837 the case of IPv6) SHOULD be copied from the inner-header 'Time to 838 Live' field. 840 o The outer-header 'Differentiated Services Code Point' (DSCP) field 841 (or the 'Traffic Class' field, in the case of IPv6) SHOULD be 842 copied from the inner-header DSCP field ('Traffic Class' field, in 843 the case of IPv6) to the outer-header. 845 o The 'Explicit Congestion Notification' (ECN) field (bits 6 and 7 846 of the IPv6 'Traffic Class' field) requires special treatment in 847 order to avoid discarding indications of congestion [RFC6040]. 848 ITR encapsulation MUST copy the 2-bit 'ECN' field from the inner 849 header to the outer header. Re-encapsulation MUST copy the 2-bit 850 'ECN' field from the stripped outer header to the new outer 851 header. 853 When doing ETR/PETR decapsulation: 855 o The inner-header 'Time to Live' field (or 'Hop Limit' field, in 856 the case of IPv6) MUST be copied from the outer-header 'Time to 857 Live' field, when the Time to Live value of the outer header is 858 less than the Time to Live value of the inner header. Failing to 859 perform this check can cause the Time to Live of the inner header 860 to increment across encapsulation/decapsulation cycles. This 861 check is also performed when doing initial encapsulation, when a 862 packet comes to an ITR or PITR destined for a LISP site. 864 o The outer-header 'Differentiated Services Code Point' (DSCP) field 865 (or the 'Traffic Class' field, in the case of IPv6) SHOULD be 866 copied from the outer-header DSCP field ('Traffic Class' field, in 867 the case of IPv6) to the inner-header. 869 o The 'Explicit Congestion Notification' (ECN) field (bits 6 and 7 870 of the IPv6 'Traffic Class' field) requires special treatment in 871 order to avoid discarding indications of congestion [RFC6040]. If 872 the 'ECN' field contains a congestion indication codepoint (the 873 value is '11', the Congestion Experienced (CE) codepoint), then 874 ETR decapsulation MUST copy the 2-bit 'ECN' field from the 875 stripped outer header to the surviving inner header that is used 876 to forward the packet beyond the ETR. These requirements preserve 877 CE indications when a packet that uses ECN traverses a LISP tunnel 878 and becomes marked with a CE indication due to congestion between 879 the tunnel endpoints. Implementations exist that copy the 'ECN' 880 field from the outer header to the inner header even though 881 [RFC6040] does not recommend this behavior. It is RECOMMENDED 882 that implementations change to support the behavior in [RFC6040]. 884 Note that if an ETR/PETR is also an ITR/PITR and chooses to re- 885 encapsulate after decapsulating, the net effect of this is that the 886 new outer header will carry the same Time to Live as the old outer 887 header minus 1. 889 Copying the Time to Live (TTL) serves two purposes: first, it 890 preserves the distance the host intended the packet to travel; 891 second, and more importantly, it provides for suppression of looping 892 packets in the event there is a loop of concatenated tunnels due to 893 misconfiguration. 895 The Explicit Congestion Notification ('ECN') field occupies bits 6 896 and 7 of both the IPv4 'Type of Service' field and the IPv6 'Traffic 897 Class' field [RFC6040]. The 'ECN' field requires special treatment 898 in order to avoid discarding indications of congestion [RFC6040]. An 899 ITR/PITR encapsulation MUST copy the 2-bit 'ECN' field from the inner 900 header to the outer header. Re-encapsulation MUST copy the 2-bit 901 'ECN' field from the stripped outer header to the new outer header. 902 If the 'ECN' field contains a congestion indication codepoint (the 903 value is '11', the Congestion Experienced (CE) codepoint), then ETR/ 904 PETR decapsulation MUST copy the 2-bit 'ECN' field from the stripped 905 outer header to the surviving inner header that is used to forward 906 the packet beyond the ETR. These requirements preserve CE 907 indications when a packet that uses ECN traverses a LISP tunnel and 908 becomes marked with a CE indication due to congestion between the 909 tunnel endpoints. 911 6. LISP EID-to-RLOC Map-Cache 913 ITRs and PITRs maintain an on-demand cache, referred as LISP EID-to- 914 RLOC Map-Cache, that contains mappings from EID-prefixes to locator 915 sets. The cache is used to encapsulate packets from the EID space to 916 the corresponding RLOC network attachment point. 918 When an ITR/PITR receives a packet from inside of the LISP site to 919 destinations outside of the site a longest-prefix match lookup of the 920 EID is done to the Map-Cache. 922 When the lookup succeeds, the Locator-Set retrieved from the Map- 923 Cache is used to send the packet to the EID's topological location. 925 If the lookup fails, the ITR/PITR needs to retrieve the mapping using 926 the LISP Control-Plane protocol [I-D.ietf-lisp-rfc6833bis]. The 927 mapping is then stored in the local Map-Cache to forward subsequent 928 packets addressed to the same EID-prefix. 930 The Map-Cache is a local cache of mappings, entries are expired based 931 on the associated Time to live. In addition, entries can be updated 932 with more current information, see Section 13 for further information 933 on this. Finally, the Map-Cache also contains reachability 934 information about EIDs and RLOCs, and uses LISP reachability 935 information mechanisms to determine the reachability of RLOCs, see 936 Section 10 for the specific mechanisms. 938 7. Dealing with Large Encapsulated Packets 940 This section proposes two mechanisms to deal with packets that exceed 941 the path MTU between the ITR and ETR. 943 It is left to the implementor to decide if the stateless or stateful 944 mechanism SHOULD be implemented. Both or neither can be used, since 945 it is a local decision in the ITR regarding how to deal with MTU 946 issues, and sites can interoperate with differing mechanisms. 948 Both stateless and stateful mechanisms also apply to Re-encapsulating 949 and Recursive Tunneling, so any actions below referring to an ITR 950 also apply to a TE-ITR. 952 7.1. A Stateless Solution to MTU Handling 954 An ITR stateless solution to handle MTU issues is described as 955 follows: 957 1. Define H to be the size, in octets, of the outer header an ITR 958 prepends to a packet. This includes the UDP and LISP header 959 lengths. 961 2. Define L to be the size, in octets, of the maximum-sized packet 962 an ITR can send to an ETR without the need for the ITR or any 963 intermediate routers to fragment the packet. 965 3. Define an architectural constant S for the maximum size of a 966 packet, in octets, an ITR MUST receive from the source so the 967 effective MTU can be met. That is, L = S + H. 969 When an ITR receives a packet from a site-facing interface and adds H 970 octets worth of encapsulation to yield a packet size greater than L 971 octets (meaning the received packet size was greater than S octets 972 from the source), it resolves the MTU issue by first splitting the 973 original packet into 2 equal-sized fragments. A LISP header is then 974 prepended to each fragment. The size of the encapsulated fragments 975 is then (S/2 + H), which is less than the ITR's estimate of the path 976 MTU between the ITR and its correspondent ETR. 978 When an ETR receives encapsulated fragments, it treats them as two 979 individually encapsulated packets. It strips the LISP headers and 980 then forwards each fragment to the destination host of the 981 destination site. The two fragments are reassembled at the 982 destination host into the single IP datagram that was originated by 983 the source host. Note that reassembly can happen at the ETR if the 984 encapsulated packet was fragmented at or after the ITR. 986 This behavior MUST be performed by the ITR only when the source host 987 originates a packet with the 'DF' field of the IP header set to 0. 988 When the 'DF' field of the IP header is set to 1, or the packet is an 989 IPv6 packet originated by the source host, the ITR will drop the 990 packet when the size is greater than L and send an ICMPv4 ICMP 991 Unreachable/Fragmentation-Needed or ICMPv6 "Packet Too Big" message 992 to the source with a value of S, where S is (L - H). 994 When the outer-header encapsulation uses an IPv4 header, an 995 implementation SHOULD set the DF bit to 1 so ETR fragment reassembly 996 can be avoided. An implementation MAY set the DF bit in such headers 997 to 0 if it has good reason to believe there are unresolvable path MTU 998 issues between the sending ITR and the receiving ETR. 1000 This specification RECOMMENDS that L be defined as 1500. 1002 7.2. A Stateful Solution to MTU Handling 1004 An ITR stateful solution to handle MTU issues is described as follows 1005 and was first introduced in [OPENLISP]: 1007 1. The ITR will keep state of the effective MTU for each Locator per 1008 Map-Cache entry. The effective MTU is what the core network can 1009 deliver along the path between the ITR and ETR. 1011 2. When an IPv6-encapsulated packet, or an IPv4-encapsulated packet 1012 with the DF bit set to 1, exceeds what the core network can 1013 deliver, one of the intermediate routers on the path will send an 1014 ICMPv6 "Packet Too Big" message or an ICMPv4 Unreachable/ 1015 Fragmentation-Needed to the ITR, respectively. The ITR will 1016 parse the ICMP message to determine which Locator is affected by 1017 the effective MTU change and then record the new effective MTU 1018 value in the Map-Cache entry. 1020 3. When a packet is received by the ITR from a source inside of the 1021 site and the size of the packet is greater than the effective MTU 1022 stored with the Map-Cache entry associated with the destination 1023 EID the packet is for, the ITR will send an ICMPv4 ICMP 1024 Unreachable/Fragmentation-Needed or ICMPv6 "Packet Too Big" 1025 message back to the source. The packet size advertised by the 1026 ITR in the ICMP message is the effective MTU minus the LISP 1027 encapsulation length. 1029 Even though this mechanism is stateful, it has advantages over the 1030 stateless IP fragmentation mechanism, by not involving the 1031 destination host with reassembly of ITR fragmented packets. 1033 8. Using Virtualization and Segmentation with LISP 1035 There are several cases where segregation is needed at the EID level. 1036 For instance, this is the case for deployments containing overlapping 1037 addresses, traffic isolation policies or multi-tenant virtualization. 1038 For these and other scenarios where segregation is needed, Instance 1039 IDs are used. 1041 An Instance ID can be carried in a LISP-encapsulated packet. An ITR 1042 that prepends a LISP header will copy a 24-bit value used by the LISP 1043 router to uniquely identify the address space. The value is copied 1044 to the 'Instance ID' field of the LISP header, and the I-bit is set 1045 to 1. 1047 When an ETR decapsulates a packet, the Instance ID from the LISP 1048 header is used as a table identifier to locate the forwarding table 1049 to use for the inner destination EID lookup. 1051 For example, an 802.1Q VLAN tag or VPN identifier could be used as a 1052 24-bit Instance ID. See [I-D.ietf-lisp-vpn] for LISP VPN use-case 1053 details. 1055 The Instance ID that is stored in the mapping database when LISP-DDT 1056 [RFC8111] is used is 32 bits in length. That means the Control-Plane 1057 can store more instances than a given Data-Plane can use. Multiple 1058 Data-Planes can use the same 32-bit space as long as the low-order 24 1059 bits don't overlap among xTRs. 1061 9. Routing Locator Selection 1063 The Map-Cache contains the state used by ITRs and PITRs to 1064 encapsulate packets. When an ITR/PITR receives a packet from inside 1065 the LISP site to a destination outside of the site a longest-prefix 1066 match lookup of the EID is done to the Map-Cache (see Section 6). 1067 The lookup returns a single Locator-Set containing a list of RLOCs 1068 corresponding to the EID's topological location. Each RLOC in the 1069 Locator-Set is associated with a 'Priority' and 'Weight', this 1070 information is used to select the RLOC to encapsulate. 1072 The RLOC with the lowest 'Priority' is selected. An RLOC with 1073 'Priority' 255 means that MUST NOT be used for forwarding. When 1074 multiple RLOC have the same 'Priority' then the 'Weight' states how 1075 to load balance traffic among them. The value of the 'Weight' 1076 represents the relative weight of the total packets that match the 1077 maping entry. 1079 The following are different scenarios for choosing RLOCs and the 1080 controls that are available: 1082 o The server-side returns one RLOC. The client-side can only use 1083 one RLOC. The server-side has complete control of the selection. 1085 o The server-side returns a list of RLOCs where a subset of the list 1086 has the same best Priority. The client can only use the subset 1087 list according to the weighting assigned by the server-side. In 1088 this case, the server-side controls both the subset list and load- 1089 splitting across its members. The client-side can use RLOCs 1090 outside of the subset list if it determines that the subset list 1091 is unreachable (unless RLOCs are set to a Priority of 255). Some 1092 sharing of control exists: the server-side determines the 1093 destination RLOC list and load distribution while the client-side 1094 has the option of using alternatives to this list if RLOCs in the 1095 list are unreachable. 1097 o The server-side sets a Weight of zero for the RLOC subset list. 1098 In this case, the client-side can choose how the traffic load is 1099 spread across the subset list. Control is shared by the server- 1100 side determining the list and the client-side determining load 1101 distribution. Again, the client can use alternative RLOCs if the 1102 server-provided list of RLOCs is unreachable. 1104 o Either side (more likely the server-side ETR) decides not to send 1105 a Map-Request. For example, if the server-side ETR does not send 1106 Map-Requests, it gleans RLOCs from the client-side ITR, giving the 1107 client-side ITR responsibility for bidirectional RLOC reachability 1108 and preferability. Server-side ETR gleaning of the client-side 1109 ITR RLOC is done by caching the inner-header source EID and the 1110 outer-header source RLOC of received packets. The client-side ITR 1111 controls how traffic is returned and can alternate using an outer- 1112 header source RLOC, which then can be added to the list the 1113 server-side ETR uses to return traffic. Since no Priority or 1114 Weights are provided using this method, the server-side ETR MUST 1115 assume that each client-side ITR RLOC uses the same best Priority 1116 with a Weight of zero. In addition, since EID-Prefix encoding 1117 cannot be conveyed in data packets, the EID-to-RLOC Cache on 1118 Tunnel Routers can grow to be very large. 1120 Instead of using the Map-Cache or mapping system, RLOC information 1121 MAY be gleaned from received tunneled packets or Map-Request 1122 messages. A "gleaned" Map-Cache entry, one learned from the source 1123 RLOC of a received encapsulated packet, is only stored and used for a 1124 few seconds, pending verification. Verification is performed by 1125 sending a Map-Request to the source EID (the inner-header IP source 1126 address) of the received encapsulated packet. A reply to this 1127 "verifying Map-Request" is used to fully populate the Map-Cache entry 1128 for the "gleaned" EID and is stored and used for the time indicated 1129 from the 'TTL' field of a received Map-Reply. When a verified Map- 1130 Cache entry is stored, data gleaning no longer occurs for subsequent 1131 packets that have a source EID that matches the EID-Prefix of the 1132 verified entry. This "gleaning" mechanism is OPTIONAL, refer to 1133 Section 16 for security issues regarding this mechanism. 1135 RLOCs that appear in EID-to-RLOC Map-Reply messages are assumed to be 1136 reachable when the R-bit [I-D.ietf-lisp-rfc6833bis] for the Locator 1137 record is set to 1. When the R-bit is set to 0, an ITR or PITR MUST 1138 NOT encapsulate to the RLOC. Neither the information contained in a 1139 Map-Reply nor that stored in the mapping database system provides 1140 reachability information for RLOCs. Note that reachability is not 1141 part of the mapping system and is determined using one or more of the 1142 Routing Locator reachability algorithms described in the next 1143 section. 1145 10. Routing Locator Reachability 1147 Several Data-Plane mechanisms for determining RLOC reachability are 1148 currently defined. Please note that additional Control-Plane based 1149 reachability mechanisms are defined in [I-D.ietf-lisp-rfc6833bis]. 1151 1. An ETR MAY examine the Locator-Status-Bits in the LISP header of 1152 an encapsulated data packet received from an ITR. If the ETR is 1153 also acting as an ITR and has traffic to return to the original 1154 ITR site, it can use this status information to help select an 1155 RLOC. 1157 2. When an ETR receives an encapsulated packet from an ITR, the 1158 source RLOC from the outer header of the packet is likely to be 1159 reachable. 1161 3. An ITR/ETR pair can use the 'Echo-Noncing' Locator reachability 1162 algorithms described in this section. 1164 When determining Locator up/down reachability by examining the 1165 Locator-Status-Bits from the LISP-encapsulated data packet, an ETR 1166 will receive up-to-date status from an encapsulating ITR about 1167 reachability for all ETRs at the site. CE-based ITRs at the source 1168 site can determine reachability relative to each other using the site 1169 IGP as follows: 1171 o Under normal circumstances, each ITR will advertise a default 1172 route into the site IGP. 1174 o If an ITR fails or if the upstream link to its PE fails, its 1175 default route will either time out or be withdrawn. 1177 Each ITR can thus observe the presence or lack of a default route 1178 originated by the others to determine the Locator-Status-Bits it sets 1179 for them. 1181 When ITRs at the site are not deployed in CE routers, the IGP can 1182 still be used to determine the reachability of Locators, provided 1183 they are injected into the IGP. This is typically done when a /32 1184 address is configured on a loopback interface. 1186 RLOCs listed in a Map-Reply are numbered with ordinals 0 to n-1. The 1187 Locator-Status-Bits in a LISP-encapsulated packet are numbered from 0 1188 to n-1 starting with the least significant bit. For example, if an 1189 RLOC listed in the 3rd position of the Map-Reply goes down (ordinal 1190 value 2), then all ITRs at the site will clear the 3rd least 1191 significant bit (xxxx x0xx) of the 'Locator-Status-Bits' field for 1192 the packets they encapsulate. 1194 When an ETR decapsulates a packet, it will check for any change in 1195 the 'Locator-Status-Bits' field. When a bit goes from 1 to 0, the 1196 ETR, if acting also as an ITR, will refrain from encapsulating 1197 packets to an RLOC that is indicated as down. It will only resume 1198 using that RLOC if the corresponding Locator-Status-Bit returns to a 1199 value of 1. Locator-Status-Bits are associated with a Locator-Set 1200 per EID-Prefix. Therefore, when a Locator becomes unreachable, the 1201 Locator-Status-Bit that corresponds to that Locator's position in the 1202 list returned by the last Map-Reply will be set to zero for that 1203 particular EID-Prefix. Refer to Section 16 for security related 1204 issues regarding Locator-Status-Bits. 1206 When an ETR decapsulates a packet, it knows that it is reachable from 1207 the encapsulating ITR because that is how the packet arrived. In 1208 most cases, the ETR can also reach the ITR but cannot assume this to 1209 be true, due to the possibility of path asymmetry. In the presence 1210 of unidirectional traffic flow from an ITR to an ETR, the ITR SHOULD 1211 NOT use the lack of return traffic as an indication that the ETR is 1212 unreachable. Instead, it MUST use an alternate mechanism to 1213 determine reachability. 1215 10.1. Echo Nonce Algorithm 1217 When data flows bidirectionally between Locators from different 1218 sites, a Data-Plane mechanism called "nonce echoing" can be used to 1219 determine reachability between an ITR and ETR. When an ITR wants to 1220 solicit a nonce echo, it sets the N- and E-bits and places a 24-bit 1221 nonce [RFC4086] in the LISP header of the next encapsulated data 1222 packet. 1224 When this packet is received by the ETR, the encapsulated packet is 1225 forwarded as normal. When the ETR is an xTR (co-located as an ITR), 1226 it next sends a data packet to the ITR (when it is an xTR co-located 1227 as an ETR), it includes the nonce received earlier with the N-bit set 1228 and E-bit cleared. The ITR sees this "echoed nonce" and knows that 1229 the path to and from the ETR is up. 1231 The ITR will set the E-bit and N-bit for every packet it sends while 1232 in the echo-nonce-request state. The time the ITR waits to process 1233 the echoed nonce before it determines the path is unreachable is 1234 variable and is a choice left for the implementation. 1236 If the ITR is receiving packets from the ETR but does not see the 1237 nonce echoed while being in the echo-nonce-request state, then the 1238 path to the ETR is unreachable. This decision MAY be overridden by 1239 other Locator reachability algorithms. Once the ITR determines that 1240 the path to the ETR is down, it can switch to another Locator for 1241 that EID-Prefix. 1243 Note that "ITR" and "ETR" are relative terms here. Both devices MUST 1244 be implementing both ITR and ETR functionality for the echo nonce 1245 mechanism to operate. 1247 The ITR and ETR MAY both go into the echo-nonce-request state at the 1248 same time. The number of packets sent or the time during which echo 1249 nonce requests are sent is an implementation-specific setting. 1250 However, when an ITR is in the echo-nonce-request state, it can echo 1251 the ETR's nonce in the next set of packets that it encapsulates and 1252 subsequently continue sending echo-nonce-request packets. 1254 This mechanism does not completely solve the forward path 1255 reachability problem, as traffic may be unidirectional. That is, the 1256 ETR receiving traffic at a site MAY not be the same device as an ITR 1257 that transmits traffic from that site, or the site-to-site traffic is 1258 unidirectional so there is no ITR returning traffic. 1260 The echo-nonce algorithm is bilateral. That is, if one side sets the 1261 E-bit and the other side is not enabled for echo-noncing, then the 1262 echoing of the nonce does not occur and the requesting side may 1263 erroneously consider the Locator unreachable. An ITR SHOULD only set 1264 the E-bit in an encapsulated data packet when it knows the ETR is 1265 enabled for echo-noncing. This is conveyed by the E-bit in the RLOC- 1266 probe Map-Reply message. 1268 11. EID Reachability within a LISP Site 1270 A site MAY be multihomed using two or more ETRs. The hosts and 1271 infrastructure within a site will be addressed using one or more EID- 1272 Prefixes that are mapped to the RLOCs of the relevant ETRs in the 1273 mapping system. One possible failure mode is for an ETR to lose 1274 reachability to one or more of the EID-Prefixes within its own site. 1275 When this occurs when the ETR sends Map-Replies, it can clear the 1276 R-bit associated with its own Locator. And when the ETR is also an 1277 ITR, it can clear its Locator-Status-Bit in the encapsulation data 1278 header. 1280 It is recognized that there are no simple solutions to the site 1281 partitioning problem because it is hard to know which part of the 1282 EID-Prefix range is partitioned and which Locators can reach any sub- 1283 ranges of the EID-Prefixes. Note that this is not a new problem 1284 introduced by the LISP architecture. The problem exists today when a 1285 multihomed site uses BGP to advertise its reachability upstream. 1287 12. Routing Locator Hashing 1289 When an ETR provides an EID-to-RLOC mapping in a Map-Reply message 1290 that is stored in the Map-Cache of a requesting ITR, the Locator-Set 1291 for the EID-Prefix MAY contain different Priority and Weight values 1292 for each locator address. When more than one best Priority Locator 1293 exists, the ITR can decide how to load-share traffic against the 1294 corresponding Locators. 1296 The following hash algorithm MAY be used by an ITR to select a 1297 Locator for a packet destined to an EID for the EID-to-RLOC mapping: 1299 1. Either a source and destination address hash or the traditional 1300 5-tuple hash can be used. The traditional 5-tuple hash includes 1301 the source and destination addresses; source and destination TCP, 1302 UDP, or Stream Control Transmission Protocol (SCTP) port numbers; 1303 and the IP protocol number field or IPv6 next-protocol fields of 1304 a packet that a host originates from within a LISP site. When a 1305 packet is not a TCP, UDP, or SCTP packet, the source and 1306 destination addresses only from the header are used to compute 1307 the hash. 1309 2. Take the hash value and divide it by the number of Locators 1310 stored in the Locator-Set for the EID-to-RLOC mapping. 1312 3. The remainder will yield a value of 0 to "number of Locators 1313 minus 1". Use the remainder to select the Locator in the 1314 Locator-Set. 1316 The specific hash algorithm the ITR uses for load-sharing is out of 1317 scope for this document and does not prevent interoperability. 1319 Note that when a packet is LISP encapsulated, the source port number 1320 in the outer UDP header needs to be set. Selecting a hashed value 1321 allows core routers that are attached to Link Aggregation Groups 1322 (LAGs) to load-split the encapsulated packets across member links of 1323 such LAGs. Otherwise, core routers would see a single flow, since 1324 packets have a source address of the ITR, for packets that are 1325 originated by different EIDs at the source site. A suggested setting 1326 for the source port number computed by an ITR is a 5-tuple hash 1327 function on the inner header, as described above. The source port 1328 SHOULD be the same for all packets belonging to the same flow. 1330 Many core router implementations use a 5-tuple hash to decide how to 1331 balance packet load across members of a LAG. The 5-tuple hash 1332 includes the source and destination addresses of the packet and the 1333 source and destination ports when the protocol number in the packet 1334 is TCP or UDP. For this reason, UDP encoding is used for LISP 1335 encapsulation. 1337 13. Changing the Contents of EID-to-RLOC Mappings 1339 Since the LISP architecture uses a caching scheme to retrieve and 1340 store EID-to-RLOC mappings, the only way an ITR can get a more up-to- 1341 date mapping is to re-request the mapping. However, the ITRs do not 1342 know when the mappings change, and the ETRs do not keep track of 1343 which ITRs requested its mappings. For scalability reasons, it is 1344 desirable to maintain this approach but need to provide a way for 1345 ETRs to change their mappings and inform the sites that are currently 1346 communicating with the ETR site using such mappings. 1348 This section defines a Data-Plane mechanism for updating EID-to-RLOC 1349 mappings. Additionally, the Solicit-Map Request (SMR) Control-Plane 1350 updating mechanism is specified in [I-D.ietf-lisp-rfc6833bis]. 1352 When adding a new Locator record in lexicographic order to the end of 1353 a Locator-Set, it is easy to update mappings. We assume that new 1354 mappings will maintain the same Locator ordering as the old mapping 1355 but will just have new Locators appended to the end of the list. So, 1356 some ITRs can have a new mapping while other ITRs have only an old 1357 mapping that is used until they time out. When an ITR has only an 1358 old mapping but detects bits set in the Locator-Status-Bits that 1359 correspond to Locators beyond the list it has cached, it simply 1360 ignores them. However, this can only happen for locator addresses 1361 that are lexicographically greater than the locator addresses in the 1362 existing Locator-Set. 1364 When a Locator record is inserted in the middle of a Locator-Set, to 1365 maintain lexicographic order, SMR procedure 1366 [I-D.ietf-lisp-rfc6833bis] is used to inform ITRs and PITRs of the 1367 new Locator-Status-Bit mappings. 1369 When a Locator record is removed from a Locator-Set, ITRs that have 1370 the mapping cached will not use the removed Locator because the xTRs 1371 will set the Locator-Status-Bit to 0. So, even if the Locator is in 1372 the list, it will not be used. For new mapping requests, the xTRs 1373 can set the Locator AFI to 0 (indicating an unspecified address), as 1374 well as setting the corresponding Locator-Status-Bit to 0. This 1375 forces ITRs with old or new mappings to avoid using the removed 1376 Locator. 1378 If many changes occur to a mapping over a long period of time, one 1379 will find empty record slots in the middle of the Locator-Set and new 1380 records appended to the Locator-Set. At some point, it would be 1381 useful to compact the Locator-Set so the Locator-Status-Bit settings 1382 can be efficiently packed. 1384 We propose here a Data-Plane mechanism (Map-Versioning specified in 1385 [I-D.ietf-lisp-6834bis]) to update the contents of EID-to-RLOC 1386 mappings. Please note that in addition the Solicit-Map Request 1387 (specified in [I-D.ietf-lisp-rfc6833bis]) is a Control-Plane 1388 mechanisms that can be used to update EID-to-RLOC mappings. 1390 13.1. Database Map-Versioning 1392 When there is unidirectional packet flow between an ITR and ETR, and 1393 the EID-to-RLOC mappings change on the ETR, it needs to inform the 1394 ITR so encapsulation to a removed Locator can stop and can instead be 1395 started to a new Locator in the Locator-Set. 1397 An ETR, when it sends Map-Reply messages, conveys its own Map-Version 1398 Number. This is known as the Destination Map-Version Number. ITRs 1399 include the Destination Map-Version Number in packets they 1400 encapsulate to the site. When an ETR decapsulates a packet and 1401 detects that the Destination Map-Version Number is less than the 1402 current version for its mapping, the SMR procedure described in 1403 [I-D.ietf-lisp-rfc6833bis] occurs. 1405 An ITR, when it encapsulates packets to ETRs, can convey its own Map- 1406 Version Number. This is known as the Source Map-Version Number. 1407 When an ETR decapsulates a packet and detects that the Source Map- 1408 Version Number is greater than the last Map-Version Number sent in a 1409 Map-Reply from the ITR's site, the ETR will send a Map-Request to one 1410 of the ETRs for the source site. 1412 A Map-Version Number is used as a sequence number per EID-Prefix, so 1413 values that are greater are considered to be more recent. A value of 1414 0 for the Source Map-Version Number or the Destination Map-Version 1415 Number conveys no versioning information, and an ITR does no 1416 comparison with previously received Map-Version Numbers. 1418 A Map-Version Number can be included in Map-Register messages as 1419 well. This is a good way for the Map-Server to assure that all ETRs 1420 for a site registering to it will be synchronized according to Map- 1421 Version Number. 1423 See [I-D.ietf-lisp-6834bis] for a more detailed analysis and 1424 description of Database Map-Versioning. 1426 14. Multicast Considerations 1428 A multicast group address, as defined in the original Internet 1429 architecture, is an identifier of a grouping of topologically 1430 independent receiver host locations. The address encoding itself 1431 does not determine the location of the receiver(s). The multicast 1432 routing protocol, and the network-based state the protocol creates, 1433 determine where the receivers are located. 1435 In the context of LISP, a multicast group address is both an EID and 1436 a Routing Locator. Therefore, no specific semantic or action needs 1437 to be taken for a destination address, as it would appear in an IP 1438 header. Therefore, a group address that appears in an inner IP 1439 header built by a source host will be used as the destination EID. 1440 The outer IP header (the destination Routing Locator address), 1441 prepended by a LISP router, can use the same group address as the 1442 destination Routing Locator, use a multicast or unicast Routing 1443 Locator obtained from a Mapping System lookup, or use other means to 1444 determine the group address mapping. 1446 With respect to the source Routing Locator address, the ITR prepends 1447 its own IP address as the source address of the outer IP header. 1448 Just like it would if the destination EID was a unicast address. 1449 This source Routing Locator address, like any other Routing Locator 1450 address, MUST be routable on the underlay. 1452 There are two approaches for LISP-Multicast, one that uses native 1453 multicast routing in the underlay with no support from the Mapping 1454 System and the other that uses only unicast routing in the underlay 1455 with support from the Mapping System. See [RFC6831] and [RFC8378], 1456 respectively, for details. Details for LISP-Multicast and 1457 interworking with non-LISP sites are described in [RFC6831] and 1458 [RFC6832]. 1460 15. Router Performance Considerations 1462 LISP is designed to be very "hardware-based forwarding friendly". A 1463 few implementation techniques can be used to incrementally implement 1464 LISP: 1466 o When a tunnel-encapsulated packet is received by an ETR, the outer 1467 destination address may not be the address of the router. This 1468 makes it challenging for the control plane to get packets from the 1469 hardware. This may be mitigated by creating special Forwarding 1470 Information Base (FIB) entries for the EID-Prefixes of EIDs served 1471 by the ETR (those for which the router provides an RLOC 1472 translation). These FIB entries are marked with a flag indicating 1473 that Control-Plane processing SHOULD be performed. The forwarding 1474 logic of testing for particular IP protocol number values is not 1475 necessary. There are a few proven cases where no changes to 1476 existing deployed hardware were needed to support the LISP Data- 1477 Plane. 1479 o On an ITR, prepending a new IP header consists of adding more 1480 octets to a MAC rewrite string and prepending the string as part 1481 of the outgoing encapsulation procedure. Routers that support 1482 Generic Routing Encapsulation (GRE) tunneling [RFC2784] or 6to4 1483 tunneling [RFC3056] may already support this action. 1485 o A packet's source address or interface the packet was received on 1486 can be used to select VRF (Virtual Routing/Forwarding). The VRF's 1487 routing table can be used to find EID-to-RLOC mappings. 1489 For performance issues related to Map-Cache management, see 1490 Section 16. 1492 16. Security Considerations 1494 A complete LISP threat analysis can be found in [RFC7835] in what 1495 follows we provide a summary when LISP is deployed in non-trustable 1496 environments. 1498 The optional mechanisms of gleaning is offered to directly obtain a 1499 mapping from the LISP encapsulated packets. Specifically, an xTR can 1500 learn the EID-to-RLOC mapping by inspecting the source RLOC and 1501 source EID of an encapsulated packet, and insert this new mapping 1502 into its Map-Cache. An off-path attacker can spoof the source EID 1503 address to divert the traffic sent to the victim's spoofed EID. If 1504 the attacker spoofs the source RLOC, it can mount a DoS attack by 1505 redirecting traffic to the spoofed victim's RLOC, potentially 1506 overloading it. 1508 The LISP Data-Plane defines several mechanisms to monitor RLOC Data- 1509 Plane reachability, in this context Locator-Status Bits, Nonce- 1510 Present and Echo-Nonce bits of the LISP encapsulation header can be 1511 manipulated by an attacker to mount a DoS attack. An off-path 1512 attacker able to spoof the RLOC of a victim's xTR can manipulate such 1513 mechanisms to declare a set of RLOCs unreachable. This can be used 1514 also, for instance, to declare only one RLOC reachable with the aim 1515 of overload it. 1517 Map-Versioning is a Data-Plane mechanism used to signal a peering xTR 1518 that a local EID-to-RLOC mapping has been updated, so that the 1519 peering xTR uses LISP Control-Plane signaling message to retrieve a 1520 fresh mapping. This can be used by an attacker to forge the map- 1521 versioning field of a LISP encapsulated header and force an excessive 1522 amount of signaling between xTRs that may overload them. 1524 Most of the attack vectors can be mitigated with careful deployment 1525 and configuration, information learned opportunistically (such as LSB 1526 or gleaning) SHOULD be verified with other reachability mechanisms. 1527 In addition, systematic rate-limitation and filtering is an effective 1528 technique to mitigate attacks that aim to overload the Control-Plane. 1530 17. Network Management Considerations 1532 Considerations for network management tools exist so the LISP 1533 protocol suite can be operationally managed. These mechanisms can be 1534 found in [RFC7052] and [RFC6835]. 1536 18. Changes since RFC 6830 1538 For implementation considerations, the following changes have been 1539 made to this document since RFC 6830 was published: 1541 o It is no longer mandated that a maximum number of 2 LISP headers 1542 be prepended to a packet. If there is a application need for more 1543 than 2 LISP headers, an implementation can support more. However, 1544 it is RECOMMENDED that a maximum of two LISP headers can be 1545 prepended to a packet. 1547 o The 3 reserved flag bits in the LISP header have been allocated 1548 for [RFC8061]. The low-order 2 bits of the 3-bit field (now named 1549 the KK bits) are used as a key identifier. The 1 remaining bit is 1550 still documented as reserved. 1552 o Data-Plane gleaning for creating map-cache entries has been made 1553 optional. Any ITR implementations that depend on or assume the 1554 remote ETR is gleaning should not do so. This does not create any 1555 interoperability problems since the control-plane map-cache 1556 population procedures are unilateral and are the typical method 1557 for map-cache population. 1559 o The bulk of the changes to this document which reduces its length 1560 are due to moving the LISP control-plane messaging and procedures 1561 to [I-D.ietf-lisp-rfc6833bis]. 1563 19. IANA Considerations 1565 This section provides guidance to the Internet Assigned Numbers 1566 Authority (IANA) regarding registration of values related to this 1567 Data-Plane LISP specification, in accordance with BCP 26 [RFC8126]. 1569 19.1. LISP UDP Port Numbers 1571 The IANA registry has allocated UDP port number 4341 for the LISP 1572 Data-Plane. IANA has updated the description for UDP port 4341 as 1573 follows: 1575 lisp-data 4341 udp LISP Data Packets 1577 20. References 1579 20.1. Normative References 1581 [I-D.ietf-lisp-6834bis] 1582 Iannone, L., Saucez, D., and O. Bonaventure, "Locator/ID 1583 Separation Protocol (LISP) Map-Versioning", draft-ietf- 1584 lisp-6834bis-02 (work in progress), September 2018. 1586 [I-D.ietf-lisp-rfc6833bis] 1587 Fuller, V., Farinacci, D., and A. Cabellos-Aparicio, 1588 "Locator/ID Separation Protocol (LISP) Control-Plane", 1589 draft-ietf-lisp-rfc6833bis-17 (work in progress), October 1590 2018. 1592 [RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768, 1593 DOI 10.17487/RFC0768, August 1980, 1594 . 1596 [RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, 1597 DOI 10.17487/RFC0791, September 1981, 1598 . 1600 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1601 Requirement Levels", BCP 14, RFC 2119, 1602 DOI 10.17487/RFC2119, March 1997, 1603 . 1605 [RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, 1606 "Definition of the Differentiated Services Field (DS 1607 Field) in the IPv4 and IPv6 Headers", RFC 2474, 1608 DOI 10.17487/RFC2474, December 1998, 1609 . 1611 [RFC6040] Briscoe, B., "Tunnelling of Explicit Congestion 1612 Notification", RFC 6040, DOI 10.17487/RFC6040, November 1613 2010, . 1615 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 1616 Writing an IANA Considerations Section in RFCs", BCP 26, 1617 RFC 8126, DOI 10.17487/RFC8126, June 2017, 1618 . 1620 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1621 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1622 May 2017, . 1624 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 1625 (IPv6) Specification", STD 86, RFC 8200, 1626 DOI 10.17487/RFC8200, July 2017, 1627 . 1629 20.2. Informative References 1631 [AFN] IANA, "Address Family Numbers", August 2016, 1632 . 1634 [CHIAPPA] Chiappa, J., "Endpoints and Endpoint names: A Proposed", 1635 1999, 1636 . 1638 [I-D.ietf-lisp-introduction] 1639 Cabellos-Aparicio, A. and D. Saucez, "An Architectural 1640 Introduction to the Locator/ID Separation Protocol 1641 (LISP)", draft-ietf-lisp-introduction-13 (work in 1642 progress), April 2015. 1644 [I-D.ietf-lisp-vpn] 1645 Moreno, V. and D. Farinacci, "LISP Virtual Private 1646 Networks (VPNs)", draft-ietf-lisp-vpn-02 (work in 1647 progress), May 2018. 1649 [OPENLISP] 1650 Iannone, L., Saucez, D., and O. Bonaventure, "OpenLISP 1651 Implementation Report", Work in Progress, July 2008. 1653 [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", 1654 STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987, 1655 . 1657 [RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G., 1658 and E. Lear, "Address Allocation for Private Internets", 1659 BCP 5, RFC 1918, DOI 10.17487/RFC1918, February 1996, 1660 . 1662 [RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P. 1663 Traina, "Generic Routing Encapsulation (GRE)", RFC 2784, 1664 DOI 10.17487/RFC2784, March 2000, 1665 . 1667 [RFC3056] Carpenter, B. and K. Moore, "Connection of IPv6 Domains 1668 via IPv4 Clouds", RFC 3056, DOI 10.17487/RFC3056, February 1669 2001, . 1671 [RFC3232] Reynolds, J., Ed., "Assigned Numbers: RFC 1700 is Replaced 1672 by an On-line Database", RFC 3232, DOI 10.17487/RFC3232, 1673 January 2002, . 1675 [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, 1676 A., Peterson, J., Sparks, R., Handley, M., and E. 1677 Schooler, "SIP: Session Initiation Protocol", RFC 3261, 1678 DOI 10.17487/RFC3261, June 2002, 1679 . 1681 [RFC4086] Eastlake 3rd, D., Schiller, J., and S. Crocker, 1682 "Randomness Requirements for Security", BCP 106, RFC 4086, 1683 DOI 10.17487/RFC4086, June 2005, 1684 . 1686 [RFC4984] Meyer, D., Ed., Zhang, L., Ed., and K. Fall, Ed., "Report 1687 from the IAB Workshop on Routing and Addressing", 1688 RFC 4984, DOI 10.17487/RFC4984, September 2007, 1689 . 1691 [RFC6831] Farinacci, D., Meyer, D., Zwiebel, J., and S. Venaas, "The 1692 Locator/ID Separation Protocol (LISP) for Multicast 1693 Environments", RFC 6831, DOI 10.17487/RFC6831, January 1694 2013, . 1696 [RFC6832] Lewis, D., Meyer, D., Farinacci, D., and V. Fuller, 1697 "Interworking between Locator/ID Separation Protocol 1698 (LISP) and Non-LISP Sites", RFC 6832, 1699 DOI 10.17487/RFC6832, January 2013, 1700 . 1702 [RFC6835] Farinacci, D. and D. Meyer, "The Locator/ID Separation 1703 Protocol Internet Groper (LIG)", RFC 6835, 1704 DOI 10.17487/RFC6835, January 2013, 1705 . 1707 [RFC6935] Eubanks, M., Chimento, P., and M. Westerlund, "IPv6 and 1708 UDP Checksums for Tunneled Packets", RFC 6935, 1709 DOI 10.17487/RFC6935, April 2013, 1710 . 1712 [RFC6936] Fairhurst, G. and M. Westerlund, "Applicability Statement 1713 for the Use of IPv6 UDP Datagrams with Zero Checksums", 1714 RFC 6936, DOI 10.17487/RFC6936, April 2013, 1715 . 1717 [RFC7052] Schudel, G., Jain, A., and V. Moreno, "Locator/ID 1718 Separation Protocol (LISP) MIB", RFC 7052, 1719 DOI 10.17487/RFC7052, October 2013, 1720 . 1722 [RFC7215] Jakab, L., Cabellos-Aparicio, A., Coras, F., Domingo- 1723 Pascual, J., and D. Lewis, "Locator/Identifier Separation 1724 Protocol (LISP) Network Element Deployment 1725 Considerations", RFC 7215, DOI 10.17487/RFC7215, April 1726 2014, . 1728 [RFC7833] Howlett, J., Hartman, S., and A. Perez-Mendez, Ed., "A 1729 RADIUS Attribute, Binding, Profiles, Name Identifier 1730 Format, and Confirmation Methods for the Security 1731 Assertion Markup Language (SAML)", RFC 7833, 1732 DOI 10.17487/RFC7833, May 2016, 1733 . 1735 [RFC7835] Saucez, D., Iannone, L., and O. Bonaventure, "Locator/ID 1736 Separation Protocol (LISP) Threat Analysis", RFC 7835, 1737 DOI 10.17487/RFC7835, April 2016, 1738 . 1740 [RFC8060] Farinacci, D., Meyer, D., and J. Snijders, "LISP Canonical 1741 Address Format (LCAF)", RFC 8060, DOI 10.17487/RFC8060, 1742 February 2017, . 1744 [RFC8061] Farinacci, D. and B. Weis, "Locator/ID Separation Protocol 1745 (LISP) Data-Plane Confidentiality", RFC 8061, 1746 DOI 10.17487/RFC8061, February 2017, 1747 . 1749 [RFC8085] Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage 1750 Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085, 1751 March 2017, . 1753 [RFC8111] Fuller, V., Lewis, D., Ermagan, V., Jain, A., and A. 1754 Smirnov, "Locator/ID Separation Protocol Delegated 1755 Database Tree (LISP-DDT)", RFC 8111, DOI 10.17487/RFC8111, 1756 May 2017, . 1758 [RFC8378] Moreno, V. and D. Farinacci, "Signal-Free Locator/ID 1759 Separation Protocol (LISP) Multicast", RFC 8378, 1760 DOI 10.17487/RFC8378, May 2018, 1761 . 1763 Appendix A. Acknowledgments 1765 An initial thank you goes to Dave Oran for planting the seeds for the 1766 initial ideas for LISP. His consultation continues to provide value 1767 to the LISP authors. 1769 A special and appreciative thank you goes to Noel Chiappa for 1770 providing architectural impetus over the past decades on separation 1771 of location and identity, as well as detailed reviews of the LISP 1772 architecture and documents, coupled with enthusiasm for making LISP a 1773 practical and incremental transition for the Internet. 1775 The original authors would like to gratefully acknowledge many people 1776 who have contributed discussions and ideas to the making of this 1777 proposal. They include Scott Brim, Andrew Partan, John Zwiebel, 1778 Jason Schiller, Lixia Zhang, Dorian Kim, Peter Schoenmaker, Vijay 1779 Gill, Geoff Huston, David Conrad, Mark Handley, Ron Bonica, Ted 1780 Seely, Mark Townsley, Chris Morrow, Brian Weis, Dave McGrew, Peter 1781 Lothberg, Dave Thaler, Eliot Lear, Shane Amante, Ved Kafle, Olivier 1782 Bonaventure, Luigi Iannone, Robin Whittle, Brian Carpenter, Joel 1783 Halpern, Terry Manderson, Roger Jorgensen, Ran Atkinson, Stig Venaas, 1784 Iljitsch van Beijnum, Roland Bless, Dana Blair, Bill Lynch, Marc 1785 Woolward, Damien Saucez, Damian Lezama, Attilla De Groot, Parantap 1786 Lahiri, David Black, Roque Gagliano, Isidor Kouvelas, Jesper Skriver, 1787 Fred Templin, Margaret Wasserman, Sam Hartman, Michael Hofling, Pedro 1788 Marques, Jari Arkko, Gregg Schudel, Srinivas Subramanian, Amit Jain, 1789 Xu Xiaohu, Dhirendra Trivedi, Yakov Rekhter, John Scudder, John 1790 Drake, Dimitri Papadimitriou, Ross Callon, Selina Heimlich, Job 1791 Snijders, Vina Ermagan, Fabio Maino, Victor Moreno, Chris White, 1792 Clarence Filsfils, Alia Atlas, Florin Coras and Alberto Rodriguez. 1794 This work originated in the Routing Research Group (RRG) of the IRTF. 1795 An individual submission was converted into the IETF LISP working 1796 group document that became this RFC. 1798 The LISP working group would like to give a special thanks to Jari 1799 Arkko, the Internet Area AD at the time that the set of LISP 1800 documents were being prepared for IESG last call, and for his 1801 meticulous reviews and detailed commentaries on the 7 working group 1802 last call documents progressing toward standards-track RFCs. 1804 The current authors would like to give a sincere thank you to the 1805 people who help put LISP on standards track in the IETF. They 1806 include Joel Halpern, Luigi Iannone, Deborah Brungard, Fabio Maino, 1807 Scott Bradner, Kyle Rose, Takeshi Takahashi, Sarah Banks, Pete 1808 Resnick, Colin Perkins, Mirja Kuhlewind, Francis Dupont, Benjamin 1809 Kaduk, Eric Rescorla, Alvaro Retana, Alexey Melnikov, Alissa Cooper, 1810 Suresh Krishnan, Alberto Rodriguez-Natal, Vina Ermagen, Mohamed 1811 Boucadair, Brian Trammell, Sabrina Tanamal, and John Drake. The 1812 contributions they offered greatly added to the security, scale, and 1813 robustness of the LISP architecture and protocols. 1815 Appendix B. Document Change Log 1817 [RFC Editor: Please delete this section on publication as RFC.] 1819 B.1. Changes to draft-ietf-lisp-rfc6830bis-24 1821 o Posted mid October 2018. 1823 o Final editorial changes for Eric and Ben. 1825 B.2. Changes to draft-ietf-lisp-rfc6830bis-23 1827 o Posted early October 2018. 1829 o Added an applicability statement in section 1 to address security 1830 concerns from Telechat. 1832 B.3. Changes to draft-ietf-lisp-rfc6830bis-22 1834 o Posted early October 2018. 1836 o Changes to reflect comments post Telechat. 1838 B.4. Changes to draft-ietf-lisp-rfc6830bis-21 1840 o Posted late-September 2018. 1842 o Changes to reflect comments from Sep 27th Telechat. 1844 B.5. Changes to draft-ietf-lisp-rfc6830bis-20 1846 o Posted late-September 2018. 1848 o Fix old reference to RFC3168, changed to RFC6040. 1850 B.6. Changes to draft-ietf-lisp-rfc6830bis-19 1852 o Posted late-September 2018. 1854 o More editorial changes. 1856 B.7. Changes to draft-ietf-lisp-rfc6830bis-18 1858 o Posted mid-September 2018. 1860 o Changes to reflect comments from Secdir review (Mirja). 1862 B.8. Changes to draft-ietf-lisp-rfc6830bis-17 1864 o Posted September 2018. 1866 o Indicate in the "Changes since RFC 6830" section why the document 1867 has been shortened in length. 1869 o Make reference to RFC 8085 about UDP congestion control. 1871 o More editorial changes from multiple IESG reviews. 1873 B.9. Changes to draft-ietf-lisp-rfc6830bis-16 1875 o Posted late August 2018. 1877 o Distinguish the message type names between ICMP for IPv4 and ICMP 1878 for IPv6 for handling MTU issues. 1880 B.10. Changes to draft-ietf-lisp-rfc6830bis-15 1882 o Posted August 2018. 1884 o Final editorial changes before RFC submission for Proposed 1885 Standard. 1887 o Added section "Changes since RFC 6830" so implementers are 1888 informed of any changes since the last RFC publication. 1890 B.11. Changes to draft-ietf-lisp-rfc6830bis-14 1892 o Posted July 2018 IETF week. 1894 o Put obsolete of RFC 6830 in Intro section in addition to abstract. 1896 B.12. Changes to draft-ietf-lisp-rfc6830bis-13 1898 o Posted March IETF Week 2018. 1900 o Clarified that a new nonce is required per RLOC. 1902 o Removed 'Clock Sweep' section. This text must be placed in a new 1903 OAM document. 1905 o Some references changed from normative to informative 1907 B.13. Changes to draft-ietf-lisp-rfc6830bis-12 1909 o Posted July 2018. 1911 o Fixed Luigi editorial comments to ready draft for RFC status. 1913 B.14. Changes to draft-ietf-lisp-rfc6830bis-11 1915 o Posted March 2018. 1917 o Removed sections 16, 17 and 18 (Mobility, Deployment and 1918 Traceroute considerations). This text must be placed in a new OAM 1919 document. 1921 B.15. Changes to draft-ietf-lisp-rfc6830bis-10 1923 o Posted March 2018. 1925 o Updated section 'Router Locator Selection' stating that the Data- 1926 Plane MUST follow what's stored in the Map-Cache (priorities and 1927 weights). 1929 o Section 'Routing Locator Reachability': Removed bullet point 2 1930 (ICMP Network/Host Unreachable),3 (hints from BGP),4 (ICMP Port 1931 Unreachable),5 (receive a Map-Reply as a response) and RLOC 1932 probing 1934 o Removed 'Solicit-Map Request'. 1936 B.16. Changes to draft-ietf-lisp-rfc6830bis-09 1938 o Posted January 2018. 1940 o Add more details in section 5.3 about DSCP processing during 1941 encapsulation and decapsulation. 1943 o Added clarity to definitions in the Definition of Terms section 1944 from various commenters. 1946 o Removed PA and PI definitions from Definition of Terms section. 1948 o More editorial changes. 1950 o Removed 4342 from IANA section and move to RFC6833 IANA section. 1952 B.17. Changes to draft-ietf-lisp-rfc6830bis-08 1954 o Posted January 2018. 1956 o Remove references to research work for any protocol mechanisms. 1958 o Document scanned to make sure it is RFC 2119 compliant. 1960 o Made changes to reflect comments from document WG shepherd Luigi 1961 Iannone. 1963 o Ran IDNITs on the document. 1965 B.18. Changes to draft-ietf-lisp-rfc6830bis-07 1967 o Posted November 2017. 1969 o Rephrase how Instance-IDs are used and don't refer to [RFC1918] 1970 addresses. 1972 B.19. Changes to draft-ietf-lisp-rfc6830bis-06 1974 o Posted October 2017. 1976 o Put RTR definition before it is used. 1978 o Rename references that are now working group drafts. 1980 o Remove "EIDs MUST NOT be used as used by a host to refer to other 1981 hosts. Note that EID blocks MAY LISP RLOCs". 1983 o Indicate what address-family can appear in data packets. 1985 o ETRs may, rather than will, be the ones to send Map-Replies. 1987 o Recommend, rather than mandate, max encapsulation headers to 2. 1989 o Reference VPN draft when introducing Instance-ID. 1991 o Indicate that SMRs can be sent when ITR/ETR are in the same node. 1993 o Clarify when private addresses can be used. 1995 B.20. Changes to draft-ietf-lisp-rfc6830bis-05 1997 o Posted August 2017. 1999 o Make it clear that a Re-encapsulating Tunnel Router is an RTR. 2001 B.21. Changes to draft-ietf-lisp-rfc6830bis-04 2003 o Posted July 2017. 2005 o Changed reference of IPv6 RFC2460 to RFC8200. 2007 o Indicate that the applicability statement for UDP zero checksums 2008 over IPv6 adheres to RFC6936. 2010 B.22. Changes to draft-ietf-lisp-rfc6830bis-03 2012 o Posted May 2017. 2014 o Move the control-plane related codepoints in the IANA 2015 Considerations section to RFC6833bis. 2017 B.23. Changes to draft-ietf-lisp-rfc6830bis-02 2019 o Posted April 2017. 2021 o Reflect some editorial comments from Damien Sausez. 2023 B.24. Changes to draft-ietf-lisp-rfc6830bis-01 2025 o Posted March 2017. 2027 o Include references to new RFCs published. 2029 o Change references from RFC6833 to RFC6833bis. 2031 o Clarified LCAF text in the IANA section. 2033 o Remove references to "experimental". 2035 B.25. Changes to draft-ietf-lisp-rfc6830bis-00 2037 o Posted December 2016. 2039 o Created working group document from draft-farinacci-lisp 2040 -rfc6830-00 individual submission. No other changes made. 2042 Authors' Addresses 2043 Dino Farinacci 2044 Cisco Systems 2045 Tasman Drive 2046 San Jose, CA 95134 2047 USA 2049 EMail: farinacci@gmail.com 2051 Vince Fuller 2052 Cisco Systems 2053 Tasman Drive 2054 San Jose, CA 95134 2055 USA 2057 EMail: vince.fuller@gmail.com 2059 Dave Meyer 2060 Cisco Systems 2061 170 Tasman Drive 2062 San Jose, CA 2063 USA 2065 EMail: dmm@1-4-5.net 2067 Darrel Lewis 2068 Cisco Systems 2069 170 Tasman Drive 2070 San Jose, CA 2071 USA 2073 EMail: darlewis@cisco.com 2075 Albert Cabellos 2076 UPC/BarcelonaTech 2077 Campus Nord, C. Jordi Girona 1-3 2078 Barcelona, Catalunya 2079 Spain 2081 EMail: acabello@ac.upc.edu