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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group A. Cabellos 3 Internet-Draft UPC-BarcelonaTech 4 Intended status: Informational D. Saucez (Ed.) 5 Expires: May 16, 2015 INRIA 6 November 12, 2014 8 An Architectural Introduction to the Locator/ID Separation Protocol 9 (LISP) 10 draft-ietf-lisp-introduction-08.txt 12 Abstract 14 This document describes the architecture of the Locator/ID Separation 15 Protocol (LISP), making it easier to read the rest of the LISP 16 specifications and providing a basis for discussion about the details 17 of the LISP protocols. This document is used for introductory 18 purposes, more details can be found in RFC6830, the protocol 19 specification. 21 Requirements Language 23 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 24 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 25 document are to be interpreted as described in RFC 2119 [RFC2119]. 27 Status of This Memo 29 This Internet-Draft is submitted in full conformance with the 30 provisions of BCP 78 and BCP 79. 32 Internet-Drafts are working documents of the Internet Engineering 33 Task Force (IETF). Note that other groups may also distribute 34 working documents as Internet-Drafts. The list of current Internet- 35 Drafts is at http://datatracker.ietf.org/drafts/current/. 37 Internet-Drafts are draft documents valid for a maximum of six months 38 and may be updated, replaced, or obsoleted by other documents at any 39 time. It is inappropriate to use Internet-Drafts as reference 40 material or to cite them other than as "work in progress." 42 This Internet-Draft will expire on May 16, 2015. 44 Copyright Notice 46 Copyright (c) 2014 IETF Trust and the persons identified as the 47 document authors. All rights reserved. 49 This document is subject to BCP 78 and the IETF Trust's Legal 50 Provisions Relating to IETF Documents 51 (http://trustee.ietf.org/license-info) in effect on the date of 52 publication of this document. Please review these documents 53 carefully, as they describe your rights and restrictions with respect 54 to this document. Code Components extracted from this document must 55 include Simplified BSD License text as described in Section 4.e of 56 the Trust Legal Provisions and are provided without warranty as 57 described in the Simplified BSD License. 59 Table of Contents 61 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 62 2. Definition of Terms . . . . . . . . . . . . . . . . . . . . . 4 63 3. LISP Architecture . . . . . . . . . . . . . . . . . . . . . . 4 64 3.1. Design Principles . . . . . . . . . . . . . . . . . . . . 4 65 3.2. Overview of the Architecture . . . . . . . . . . . . . . 5 66 3.3. Data-Plane . . . . . . . . . . . . . . . . . . . . . . . 8 67 3.3.1. LISP Encapsulation . . . . . . . . . . . . . . . . . 8 68 3.3.2. LISP Forwarding State . . . . . . . . . . . . . . . . 9 69 3.4. Control-Plane . . . . . . . . . . . . . . . . . . . . . . 9 70 3.4.1. LISP Mappings . . . . . . . . . . . . . . . . . . . . 10 71 3.4.2. Mapping System Interface . . . . . . . . . . . . . . 10 72 3.4.3. Mapping System . . . . . . . . . . . . . . . . . . . 11 73 3.5. Interworking Mechanisms . . . . . . . . . . . . . . . . . 14 74 4. LISP Operational Mechanisms . . . . . . . . . . . . . . . . . 14 75 4.1. Cache Management . . . . . . . . . . . . . . . . . . . . 15 76 4.2. RLOC Reachability . . . . . . . . . . . . . . . . . . . . 15 77 4.3. ETR Synchronization . . . . . . . . . . . . . . . . . . . 17 78 4.4. MTU Handling . . . . . . . . . . . . . . . . . . . . . . 17 79 5. Mobility . . . . . . . . . . . . . . . . . . . . . . . . . . 17 80 6. Multicast . . . . . . . . . . . . . . . . . . . . . . . . . . 18 81 7. Security Considerations . . . . . . . . . . . . . . . . . . . 19 82 8. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 20 83 8.1. Traffic Engineering . . . . . . . . . . . . . . . . . . . 20 84 8.2. LISP for IPv6 Co-existence . . . . . . . . . . . . . . . 20 85 8.3. LISP for Virtual Private Networks . . . . . . . . . . . . 21 86 8.4. LISP for Virtual Machine Mobility in Data Centers . . . . 21 87 9. Security Considerations . . . . . . . . . . . . . . . . . . . 22 88 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22 89 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 22 90 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 22 91 12.1. Normative References . . . . . . . . . . . . . . . . . . 22 92 12.2. Informative References . . . . . . . . . . . . . . . . . 23 93 Appendix A. A Brief History of Location/Identity Separation . . 25 94 A.1. Old LISP Models . . . . . . . . . . . . . . . . . . . . . 25 95 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 26 97 1. Introduction 99 This document introduces the Locator/ID Separation Protocol (LISP) 100 [RFC6830] architecture, its main operational mechanisms and its 101 design rationale. Fundamentally, LISP is built following a well- 102 known architectural idea: decoupling the IP address overloaded 103 semantics. Indeed and as pointed out by [Chiappa], currently IP 104 addresses both identify the topological location of a network 105 attachment point as well as the node's identity. However, nodes and 106 routing have fundamentally different requirements, routing systems 107 require that addresses are aggregatable and have topological meaning, 108 while nodes require to be identified independently of their current 109 location [RFC4984]. 111 LISP creates two separate namespaces, EIDs (End-host IDentifiers) and 112 RLOCs (Routing LOCators), both are typically syntactically identical 113 to the current IPv4 and IPv6 addresses. EIDs are used to uniquely 114 identify nodes irrespective of their topological location and are 115 typically routed intra-domain. RLOCs are assigned topologically to 116 network attachment points and are typically routed inter-domain. 117 With LISP, the edge of the Internet (where the nodes are connected) 118 and the core (where inter-domain routing occurs) can be logically 119 separated and interconnected by LISP-capable routers. LISP also 120 introduces a database, called the Mapping System, to store and 121 retrieve mappings between identity and location. LISP-capable 122 routers exchange packets over the Internet core by encapsulating them 123 to the appropriate location. 125 In summary: 127 o RLOCs have meaning only in the underlay network 129 o EIDs have meaning only in the overlay network (unless they are 130 leaked into the underlay network) 132 o The LISP edge maps EIDs to RLOCs 134 o Within the underlay network, RLOCs have both locator and 135 identifier semantics 137 o An EID within a LISP site carries both identifier and locator 138 semantics to other nodes within that site 140 o An EID within a LISP site carries identifier and limited locator 141 semantics to nodes at other LISP sites (i.e., enough locator 142 information to tell that the EID is external to the site) 144 The relationship described above is not unique to LISP but it is 145 common to other overlay technologies. 147 The initial motivation in the LISP effort is to be find in the 148 routing scalability problem [RFC4984], where, if LISP is completely 149 deployed, the Internet core is populated with RLOCs while Traffic 150 Engineering mechanisms are pushed to the Mapping System. Where RLOCs 151 are quasi-static (i.e., low churn) and hence, the routing system 152 scalable [Quoitin] while EIDs can roam anywhere with no churn to the 153 underlying routing system. However, the separation between location 154 and identity that LISP offers makes it suitable for use in additional 155 scenarios such as Traffic Engineering (TE), multihoming, and mobility 156 among others. 158 This document describes the LISP architecture, its main operational 159 mechanisms as its design rationale. It is important to note that 160 this document does not specify or complement the LISP protocol. The 161 interested reader should refer to the main LISP specifications 162 [RFC6830] and the complementary documents [RFC6831], [RFC6832], 163 [RFC6833], [RFC6834], [RFC6835], [RFC6836], [RFC7052] for the 164 protocol specifications along with the LISP deployment guidelines 165 [RFC7215]. 167 2. Definition of Terms 169 This document describes the LISP architecture and does not define or 170 introduce any new term. The reader is referred to [RFC6830], 171 [RFC6831], [RFC6832], [RFC6833], [RFC6834], [RFC6835], [RFC6836], 172 [RFC7052], [RFC7215] for the LISP definition of terms. 174 3. LISP Architecture 176 This section presents the LISP architecture, it first details the 177 design principles of LISP and then it proceeds to describe its main 178 aspects: data-plane, control-plane, and inetrworking mechanisms. 180 3.1. Design Principles 182 The LISP architecture is built on top of four basic design 183 principles: 185 o Locator/Identifier split: By decoupling the overloaded semantics 186 of the current IP addresses the Internet core can be assigned 187 identity meaningful addresses and hence, can use aggregation to 188 scale. Devices are assigned with relatively opaque identity 189 meaningful addresses that are independent of their topological 190 location. 192 o Overlay architecture: Overlays route packets over the current 193 Internet, allowing deployment of new protocols without changing 194 the current infrastructure hence, resulting into a low deployment 195 cost. 197 o Decoupled data and control-plane: Separating the data-plane from 198 the control-plane allows them to scale independently and use 199 different architectural approaches. This is important given that 200 they typically have different requirements and allows for other 201 data-planes to be added. While decoupled, data and control-plane 202 are not completely isolated because the LISP data-plane may 203 trigger control-plane activity. 205 o Incremental deployability: This principle ensures that the 206 protocol interoperates with the legacy Internet while providing 207 some of the targeted benefits to early adopters. 209 3.2. Overview of the Architecture 211 LISP splits architecturally the core from the edge of the Internet by 212 creating two separate namespaces: Endpoint Identifiers (EIDs) and 213 Routing LOCators (RLOCs). The edge consists of LISP sites (e.g., an 214 Autonomous System) that use EID addresses. EIDs are typically -but 215 not limited to- IPv4 or IPv6 addresses that uniquely identify 216 communication end-hosts and are assigned and configured by the same 217 mechanisms that exist at the time of this writing. EIDs do not 218 contain inter-domain topological information and can be thought as an 219 analogy to Provider Independent (PI [RFC4116]) addresses. Because of 220 this, EIDs are usually only routable at the edge with a LISP site. 222 With LISP, LISP sites (edge) and the core of the Internet are 223 interconnected by means of LISP-capable routers (e.g., border 224 routers) using tunnels. When packets originated from a LISP site are 225 flowing towards the core network, they ingress into an encapsulated 226 tunnel via an Ingress Tunnel Router (ITR). When packets flow from 227 the core network to a LISP site, they egress from an encapsulated 228 tunnel to an Egress Tunnel Router (ETR). An xTR is a router which 229 can perform both ITR and ETR operations. In this context ITRs 230 encapsulate packets while ETRs decapsulate them, hence LISP operates 231 as an overlay on top of the current Internet core. 233 /-----------------\ --- 234 | Mapping | | 235 . System | | Control 236 -| |`, | Plane 237 ,' \-----------------/ . | 238 / \ --- 239 ,.., - _,..--..,, `, ,.., | 240 / ` ,' ,-` `', . / ` | 241 / \ +-----+ ,' `, +--'--+ / \ | 242 | EID |-| xTR |---/ RLOC ,---| xTR |-| EID | | Data 243 | Space |-| |---| Space |---| |-| Space | | Plane 244 \ / +-----+ . / +-----+ \ / | 245 `. .' `. ,' `. .' | 246 `'-` `., ,.' `'-` --- 247 ``''--''`` 248 LISP Site (Edge) Core LISP Site (Edge) 250 Figure 1.- A schema of the LISP Architecture 252 With LISP, the core uses RLOCs, an RLOC is typically -but not limited 253 to- an IPv4 or IPv6 address assigned to an Internet-facing network 254 interface of an ITR or ETR. Typically RLOCs are numbered from 255 topologically aggregatable blocks assigned to a site at each point to 256 which it attaches to the global Internet. The topology is defined by 257 the connectivity of networks, in this context RLOCs can be thought of 258 Provider Aggregatable addresses [RFC4116]. 260 A typically distributed database, called the Mapping System, stores 261 mappings between EIDs and RLOCs. Such mappings relate the identity 262 of the devices attached to LISP sites (EIDs) to the set of RLOCs 263 configured at the LISP-capable routers servicing the site. 264 Furthermore, the mappings also include traffic engineering policies 265 and can be configured to achieve multihoming and load balancing. The 266 LISP Mapping System is conceptually similar to the DNS where it is 267 organized as a distributed multi-organization network database. With 268 LISP, ETRs register mappings while ITRs retrieve them. 270 Finally, the LISP architecture emphasizes a cost effective 271 incremental deployment. Given that LISP represents an overlay to the 272 current Internet architecture, endhosts as well as intra and inter- 273 domain routers remain unchanged, and the only required changes to the 274 existing infrastructure are to routers connecting the EID with the 275 RLOC space. Such LISP capable routers, in most cases, only require a 276 software upgrade. Additionally, LISP requires the deployment of an 277 independent Mapping System, such distributed database is a new 278 network entity. 280 The following describes a simplified packet flow sequence between two 281 nodes that are attached to LISP sites. Client HostA wants to send a 282 packet to server HostB. 284 /----------------\ 285 | Mapping | 286 | System | 287 .| |- 288 ` \----------------/ `. 289 ,` \ 290 / `. 291 ,' _,..-..,, ', 292 / -` `-, \ 293 .' ,' \ `, 294 ` ' \ ' 295 +-----+ | | RLOC_B1+-----+ 296 HostA | | | RLOC |-------| | HostB 297 EID_A--|ITR_A|----| Space | |ETR_B|--EID_B 298 | | RLOC_A1 |-------| | 299 +-----+ | | RLOC_B2+-----+ 300 , / 301 \ / 302 `', ,-` 303 ``''-''`` 305 Figure 2.- Packet flow sequence in LISP 307 1. HostA retrieves the EID_B of HostB (typically querying the DNS) 308 and generates an IP packet as in the Internet, the packet has 309 source address EID_A and destination address EID_B. 311 2. The packet is routed towards ITR_A in the LISP site using 312 standard intra-domain mechanisms. 314 3. ITR_A upon receiving the packet queries the Mapping System to 315 retrieve the locator of ETR_B that is servicing HostB's EID_B. 316 In order to do so it uses a LISP control message called Map- 317 Request, the message contains EID_B as the lookup key. In turn 318 it receives another LISP control message called Map-Reply, the 319 message contains two locators: RLOC_B1 and RLOC_B2 along with 320 traffic engineering policies: priority and weight per locator. 321 ITR_A also stores the mapping in a local cache to speed-up 322 forwarding of subsequent packets. 324 4. ITR_A encapsulates the packet towards RLOC_B1 (chosen according 325 to the priorities/weights specified in the mapping). The packet 326 contains two IP headers, the outer header has RLOC_A1 as source 327 and RLOC_B2 as destination, the inner original header has EID_A 328 as source and EID_B as destination. Furthermore ITR_A adds a 329 LISP header, more details about LISP encapsulation can be found 330 in Section 3.3.1. 332 5. The encapsulated packet is forwarded by the Internet core as a 333 normal IP packet, making the EID invisible from the Internet 334 core. 336 6. Upon reception of the encapsulated packet by ETR_B, it 337 decapsulates the packet and forwards it to HostB. 339 3.3. Data-Plane 341 This section provides a high-level description of the LISP data- 342 plane, which is specified in detail in [RFC6830]. The LISP data- 343 plane is responsible for encapsulating and decapsulating data packets 344 and caching the appropriate forwarding state. It includes two main 345 entities, the ITR and the ETR, both are LISP capable routers that 346 connect the EID with the RLOC space (ITR) and vice versa (ETR). 348 3.3.1. LISP Encapsulation 350 ITRs encapsulate data packets towards ETRs. LISP data packets are 351 encapsulated using UDP (port 4341). A particularity of LISP is that 352 UDP packets should include a zero checksum [RFC6935] [RFC6936] that 353 it is not verified in reception, LISP also supports non-zero 354 checksums that may be verified. This decision was made because the 355 typical transport protocols used by the applications already include 356 a checksum, by neglecting the additional UDP encapsulation checksum 357 xTRs can forward packets more efficiently. 359 LISP-encapsulated packets also include a LISP header (after the UDP 360 header and before the original IP header). The LISP header is 361 prepended by ITRs and striped by ETRs. It carries reachability 362 information (see more details in Section 4.2) and the Instance ID 363 field. The Instance ID field is used to distinguish traffic to/from 364 different tenant address spaces at the LISP site and that may use 365 overlapped but logically separated EID addressing. 367 Overall, LISP works on 4 headers, the inner header the source 368 constructed, and the 3 headers a LISP encapsulator prepends ("outer" 369 to "inner"): 371 1. Outer IP header containing RLOCs as source and destination 372 addresses. This header is originated by ITRs and stripped by 373 ETRs. 375 2. UDP header (port 4341) with zero checksum. This header is 376 originated by ITRs and stripped by ETRs. 378 3. LISP header that contains various forwarding-plane features (such 379 as reachability) and an Instance ID field. This header is 380 originated by ITRs and stripped by ETRs. 382 4. Inner IP header containing EIDs as source and destination 383 addresses. This header is created by the source end-host and is 384 left unchanged by LISP data plane processing on the ITR and ETR. 386 Finally, in some scenarios Recursive and/or Re-encapsulating tunnels 387 can be used for Traffic Engineering and re-routing. Re-encapsulating 388 tunnels are consecutive LISP tunnels and occur when a decapsulator 389 (an ETR action) removes a LISP header and then acts as an encapsultor 390 (an ITR action) to prepend another one. On the other hand, Recursive 391 tunnels are nested tunnels and are implemented by using multiple LISP 392 encapsulations on a packet. Typically such functions are implemented 393 by Reencapsulating Tunnel Routers (RTRs). 395 3.3.2. LISP Forwarding State 397 In the LISP architecture, ITRs keep just enough information to route 398 traffic flowing through it. Meaning that, ITRs retrieve from the 399 LISP Mapping System mappings between EID prefixes and RLOCs that are 400 used to encapsulate packets. Such mappings are stored in a local 401 cache called the Map-Cache for subsequent packets addressed to the 402 same EID prefix. Note that, in case of overlapping EID-prefixes, 403 following a single request, the ITR may receive a set of mappings, 404 covering the requested EID-prefix and all more-specifics (cf., 405 Section 6.1.5 [RFC6830]). Mappings include a (Time-to-Live) TTL (set 406 by the ETR). More details about the Map-Cache management can be 407 found in Section 4.1. 409 3.4. Control-Plane 411 The LISP control-plane, specified in [RFC6833], provides a standard 412 interface to register and request mappings. The LISP Mapping System 413 is a database that stores such mappings. The following first 414 describes the mappings, then the standard interface to the Mapping 415 System, and finally its architecture. 417 3.4.1. LISP Mappings 419 Each mapping includes the bindings between EID prefix(es) and set of 420 RLOCs as well as traffic engineering policies, in the form of 421 priorities and weights for the RLOCs. Priorities allow the ETR to 422 configure active/backup policies while weights are used to load- 423 balance traffic among the RLOCs (on a per-flow basis). 425 Typical mappings in LISP bind EIDs in the form of IP prefixes with a 426 set of RLOCs, also in the form of IPs. IPv4 and IPv6 addresses are 427 encoded using the appropriate Address Family Identifier (AFI) 428 [RFC3232]. However LISP can also support more general address 429 encoding by means of the ongoing effort around the LISP Canonical 430 Address Format (LCAF) [I-D.ietf-lisp-lcaf]. 432 With such a general syntax for address encoding in place, LISP aims 433 to provide flexibility to current and future applications. For 434 instance LCAFs could support MAC addresses, geo-coordinates, ASCII 435 names and application specific data. 437 3.4.2. Mapping System Interface 439 LISP defines a standard interface between data and control planes. 440 The interface is specified in [RFC6833] and defines two entities: 442 Map-Server: A network infrastructure component that learns mappings 443 from ETRs and publishes them into the LISP Mapping System. 444 Typically Map-Servers are not authoritative to reply to queries 445 and hence, they forward them to the ETR. However they can also 446 operate in proxy-mode, where the ETRs delegate replying to queries 447 to Map-Servers. This setup is useful when the ETR has limited 448 resources (i.e., CPU or power). 450 Map-Resolver: A network infrastructure component that interfaces 451 ITRs with the Mapping System by proxying queries and in some cases 452 responses. 454 The interface defines four LISP control messages which are sent as 455 UDP datagrams (port 4342): 457 Map-Register: This message is used by ETRs to register mappings in 458 the Mapping System and it is authenticated using a shared key 459 between the ETR and the Map-Server. 461 Map-Notify: When requested by the ETR, this message is sent by the 462 Map-Server in response to a Map-Register to acknowledge the 463 correct reception of the mapping and convey the latest Map-Server 464 state on the EID to RLOC mapping. In some cases a Map-Notify can 465 be sent to the previous RLOCs when an EID is registered by a new 466 set of RLOCs. 468 Map-Request: This message is used by ITRs or Map-Resolvers to 469 resolve the mapping of a given EID. 471 Map-Reply: This message is sent by Map-Servers or ETRs in response 472 to a Map-Request and contains the resolved mapping. Please note 473 that a Map-Reply may contain a negative reply if, for example, the 474 queried EID is not part of the LISP EID space. In such cases the 475 ITR typically forwards the traffic natively (non encapsulated) to 476 the public Internet, this behavior is defined to support 477 incremental deployment of LISP. 479 3.4.3. Mapping System 481 LISP architecturally decouples control and data-plane by means of a 482 standard interface. This interface glues the data-plane, routers 483 responsible for forwarding data-packets, with the LISP Mapping 484 System, a database responsible for storing mappings. 486 With this separation in place the data and control-plane can use 487 different architectures if needed and scale independently. Typically 488 the data-plane is optimized to route packets according to 489 hierarchical IP addresses. However the control-plane may have 490 different requirements, for instance and by taking advantage of the 491 LCAFs, the Mapping System may be used to store non-hierarchical keys 492 (such as MAC addresses), requiring different architectural approaches 493 for scalability. Another important difference between the LISP 494 control and data-planes is that, and as a result of the local mapping 495 cache available at ITR, the Mapping System does not need to operate 496 at line-rate. 498 The LISP WG has explored application of the following distributed 499 system techniques to the Mapping System architecture: graph-based 500 databases in the form of LISP+ALT [RFC6836], hierarchical databases 501 in the form of LISP-DDT [I-D.ietf-lisp-ddt], monolithic databases in 502 the form of LISP-NERD [RFC6837], flat databases in the form of LISP- 503 DHT [I-D.cheng-lisp-shdht],[I-D.mathy-lisp-dht] and, a multicast- 504 based database [I-D.curran-lisp-emacs]. Furthermore it is worth 505 noting that, in some scenarios such as private deployments, the 506 Mapping System can operate as logically centralized. In such cases 507 it is typically composed of a single Map-Server/Map-Resolver. 509 The following focuses on the two mapping systems that have been 510 implemented and deployed (LISP-ALT and LISP+DDT). 512 3.4.3.1. LISP+ALT 514 The LISP Alternative Topology (LISP+ALT) [RFC6836] was the first 515 Mapping System proposed, developed and deployed on the LISP pilot 516 network. It is based on a distributed BGP overlay participated by 517 Map-Servers and Map-Resolvers. The nodes connect to their peers 518 through static tunnels. Each Map-Server involved in the ALT topology 519 advertises the EID-prefixes registered by the serviced ETRs, making 520 the EID routable on the ALT topology. 522 When an ITR needs a mapping it sends a Map-Request to a Map-Resolver 523 that, using the ALT topology, forwards the Map-Request towards the 524 Map-Server responsible for the mapping. Upon reception the Map- 525 Server forwards the request to the ETR that in turn, replies directly 526 to the ITR using the native Internet core. 528 3.4.3.2. LISP-DDT 530 LISP-DDT [I-D.ietf-lisp-ddt] is conceptually similar to the DNS, a 531 hierarchical directory whose internal structure mirrors the 532 hierarchical nature of the EID address space. The DDT hierarchy is 533 composed of DDT nodes forming a tree structure, the leafs of the tree 534 are Map-Servers. On top of the structure there is the DDT root node 535 [DDT-ROOT], which is a particular instance of a DDT node and that 536 matches the entire address space. As in the case of DNS, DDT 537 supports multiple redundant DDT nodes and/or DDT roots. Finally, 538 Map-Resolvers are the clients of the DDT hierarchy and can query 539 either the DDT root and/or other DDT nodes. 541 /---------\ 542 | | 543 | DDT Root| 544 | /0 | 545 ,.\---------/-, 546 ,-'` | `'., 547 -'` | `- 548 /-------\ /-------\ /-------\ 549 | DDT | | DDT | | DDT | 550 | Node | | Node | | Note | ... 551 | 0/8 | | 1/8 | | 2/8 | 552 \-------/ \-------/ \-------/ 553 _. _. . -..,,,_ 554 -` -` \ ````''-- 555 +------------+ +------------+ +------------+ +------------+ 556 | Map-Server | | Map-Server | | Map-Server | | Map-Server | 557 | EID-prefix1| | EID-prefix2| | EID-prefix3| | EID-prefix4| 558 +------------+ +------------+ +------------+ +------------+ 560 Figure 3.- A schematic representation of the DDT tree structure, 561 please note that the prefixes and the structure depicted 562 should be only considered as an example. 564 The DDT structure does not actually index EID-prefixes but eXtended 565 EID-prefixes (XEID). An XEID-prefix is just the concatenation of the 566 following fields (from most significant bit to less significant bit): 567 Database-ID, Instance ID, Address Family Identifier and the actual 568 EID-prefix. The Database-ID is provided for possible future 569 requirements of higher levels in the hierarchy and to enable the 570 creation of multiple and separate database trees. 572 In order to resolve a query LISP-DDT operates in a similar way to the 573 DNS but only supports iterative lookups. DDT clients (usually Map- 574 Resolvers) generate Map-Requests to the DDT root node. In response 575 they receive a newly introduced LISP-control message: a Map-Referral. 576 A Map-Referral provides the list of RLOCs of the set of DDT nodes 577 matching a configured XEID delegation. That is, the information 578 contained in the Map-Referral points to the child of the queried DDT 579 node that has more specific information about the queried XEID- 580 prefix. This process is repeated until the DDT client walks the tree 581 structure (downwards) and discovers the Map-Server servicing the 582 queried XEID. At this point the client sends a Map-Request and 583 receives a Map-Reply containing the mappings. It is important to 584 note that DDT clients can also cache the information contained in 585 Map-Referrals, that is, they cache the DDT structure. This is used 586 to reduce the mapping retrieving latency[Jakab]. 588 The DDT Mapping System relies on manual configuration. That is Map- 589 Resolvers are manually configured with the set of available DDT root 590 nodes while DDT nodes are manually configured with the appropriate 591 XEID delegations. Configuration changes in the DDT nodes are only 592 required when the tree structure changes itself, but it doesn't 593 depend on EID dynamics (RLOC allocation or traffic engineering policy 594 changes). 596 3.5. Interworking Mechanisms 598 EIDs are typically identical to either IPv4 or IPv6 addresses and 599 they are stored in the LISP Mapping System, however they are usually 600 not announced in the Internet global routing system. As a result 601 LISP requires an inetrworking mechanism to allow LISP sites to speak 602 with non-LISP sites and vice versa. LISP inetrworking mechanisms are 603 specified in [RFC6832]. 605 LISP defines two entities to provide inetrworking: 607 Proxy Ingress Tunnel Router (PITR): PITRs provide connectivity from 608 the legacy Internet to LISP sites. PITRs announce in the global 609 routing system blocks of EID prefixes (aggregating when possible) 610 to attract traffic. For each incoming packet from a source not in 611 a LISP site (a non-EID), the PITR LISP-encapsulates it towards the 612 RLOC(s) of the appropriate LISP site. The impact of PITRs in the 613 routing table size of the DFZ is, in the worst-case, similar to 614 the case in which LISP is not deployed. EID-prefixes will be 615 aggregated as much as possible both by the PITR and by the global 616 routing system. 618 Proxy Egress Tunnel Router (PETR): PETRs provide connectivity from 619 LISP sites to the legacy Internet. In some scenarios, LISP sites 620 may be unable to send encapsulated packets with a local EID 621 address as a source to the legacy Internet. For instance when 622 Unicast Reverse Path Forwarding (uRPF) is used by Provider Edge 623 routers, or when an intermediate network between a LISP site and a 624 non-LISP site does not support the desired version of IP (IPv4 or 625 IPv6). In both cases the PETR overcomes such limitations by 626 encapsulating packets over the network. There is no specified 627 provision for the distribution of PETR RLOC addresses to the ITRs. 629 4. LISP Operational Mechanisms 631 This section details the main operational mechanisms defined in LISP. 633 4.1. Cache Management 635 LISP's decoupled control and data-plane, where mappings are stored in 636 the control-plane and used for forwarding in the data plane, requires 637 of a local cache in ITRs to reduce signaling overhead (Map-Request/ 638 Map-Reply) and increase forwarding speed. The local cache available 639 at the ITRs, called Map-Cache, is used by the router to LISP- 640 encapsulate packets. The Map-Cache is indexed by (Instance ID, EID- 641 prefix) and contains basically the set of RLOCs with the associated 642 traffic engineering policies (priorities and weights). 644 The Map-Cache, as any other cache, requires cache coherence 645 mechanisms to maintain up-to-date information. LISP defines three 646 main mechanisms for cache coherence: 648 Time-To-Live (TTL): Each mapping contains a TTL set by the ETR, upon 649 expiration of the TTL the ITR has to refresh the mapping by 650 sending a new Map-Request. Typical values for TTL defined by LISP 651 are 24 hours. 653 Solicit-Map-Request (SMR): SMR is an explicit mechanism to update 654 mapping information. In particular a special type of Map-Request 655 can be sent on demand by ETRs to request refreshing a mapping. 656 Upon reception of a SMR message, the ITR must refresh the bindings 657 by sending a Map-Request to the Mapping System. 659 Map-Versioning: This optional mechanism piggybacks in the LISP 660 header of data-packets the version number of the mappings used by 661 an xTR. This way, when an xTR receives a LISP-encapsulated packet 662 from a remote xTR, it can check whether its own Map-Cache or the 663 one of the remote xTR is outdated. If its Map-Cache is outdated, 664 it sends a Map-Request for the remote EID so to obtain the newest 665 mappings. On the contrary, if it detects that the remote xTR Map- 666 Cache is outdated, it sends a SMR to notify it that a new mapping 667 is available. 669 Finally it is worth noting that in some cases an entry in the map- 670 cache can be proactively refreshed using the mechanisms described in 671 the section below. 673 4.2. RLOC Reachability 675 The LISP architecture is an edge to edge pull architecture, where the 676 network state is stored in the control-plane while the data-plane 677 pulls it on demand. This has consequences concerning the propagation 678 of xTRs reachability/liveness information. On the contrary BGP is a 679 push architecture, where the required network state is pushed by 680 means of BGP UPDATE messages to BGP speakers. In push architectures, 681 reachability information is also pushed to the interested routers. 682 However pull architectures require explicit mechanisms to propagate 683 reachability information. LISP defines a set of mechanisms to inform 684 ITRs and PITRS about the reachability of the cached RLOCs: 686 Locator Status Bits (LSB): LSB is a passive technique, the LSB field 687 is carried by data-packets in the LISP header and can be set by a 688 ETRs to specify which RLOCs of the ETR site are up/down. This 689 information can be used by the ITRs as a hint about the reachability 690 to perform additional checks. Also note that LSB does not provide 691 path reachability status, only hints on the status of RLOCs. 693 Echo-nonce: This is also a passive technique, that can only operate 694 effectively when data flows bi-directionally between two 695 communicating xTRs. Basically, an ITR piggybacks a random number 696 (called nonce) in LISP data packets, if the path and the probed 697 locator are up, the ETR will piggyback the same random number on the 698 next data-packet, if this is not the case the ITR can set the locator 699 as unreachable. When traffic flow is unidirectional or when the ETR 700 receiving the traffic is not the same as the ITR that transmits it 701 back, additional mechanisms are required. 703 RLOC-probing: This is an active probing algorithm where ITRs send 704 probes to specific locators, this effectively probes both the locator 705 and the path. In particular this is done by sending a Map-Request 706 (with certain flags activated) on the data-plane (RLOC space) and 707 waiting in return a Map-Reply, also sent on the data-plane. The 708 active nature of RLOC-probing provides an effective mechanism to 709 determine reachability and, in case of failure, switching to a 710 different locator. Furthermore the mechanism also provides useful 711 RTT estimates of the delay of the path that can be used by other 712 network algorithms. 714 Additionally, LISP also recommends inferring reachability of locators 715 by using information provided by the underlay, in particular: 717 It is worth noting that RLOC probing and Echo-nonce can work 718 together. Specifically if a nonce is not echoed, an ITR could RLOC- 719 probe to determine if the path is up when it cannot tell the 720 difference between a failed bidirectional path or the return path is 721 not used (a unidirectional path). 723 ICMP signaling: The LISP underlay -the current Internet- uses the 724 ICMP protocol to signal unreachability (among other things). LISP 725 can take advantage of this and the reception of a ICMP Network 726 Unreachable or ICMP Host Unreachable message can be seen as a hint 727 that a locator might be unreachable, this should lead to perform 728 additional checks. 730 Underlay routing: Both BGP and IBGP carry reachability information, 731 LISP-capable routers that have access to underlay routing information 732 can use it to determine if a given locator or path are reachable. 734 4.3. ETR Synchronization 736 All the ETRs that are authoritative to a particular EID-prefix must 737 announce the same mapping to the requesters, this means that ETRs 738 must be aware of the status of the RLOCs of the remaining ETRs. This 739 is known as ETR synchronization. 741 At the time of this writing LISP does not specify a mechanism to 742 achieve ETR synchronization. Although many well-known techniques 743 could be applied to solve this issue it is still under research, as a 744 result operators must rely on coherent manual configuration 746 4.4. MTU Handling 748 Since LISP encapsulates packets it requires dealing with packets that 749 exceed the MTU of the path between the ITR and the ETR. Specifically 750 LISP defines two mechanisms: 752 Stateless: With this mechanism the effective MTU is assumed from the 753 ITR's perspective. If a payload packet is too big for the 754 effective MTU, and can be fragmented, the payload packet is 755 fragmented on the ITR, such that reassembly is performed at the 756 destination host. 758 Stateful: With this mechanism ITRs keep track of the MTU of the 759 paths towards the destination locators by parsing the ICMP Too Big 760 packets sent by intermediate routers. Additionally ITRs will send 761 ICMP Too Big messages to inform the sources about the effective 762 MTU. 764 In both cases if the packet cannot be fragmented (IPv4 with DF=1 or 765 IPv6) then the ITR drops it and replies with a ICMP Too Big message 766 to the source. 768 5. Mobility 770 The separation between locators and identifiers in LISP was initially 771 proposed for traffic engineering purpose where LISP sites can change 772 their attachment points to the Internet (i.e., RLOCs) without 773 impacting endpoints or the Internet core. In this context, the 774 border routers operate the xTR functionality and endpoints are not 775 aware of the existence of LISP. However, this mode of operation does 776 not allow seamless mobility of endpoints between different LISP sites 777 as the EID address might not be routable in a visited site. 779 Nevertheless, LISP can be used to enable seamless IP mobility when 780 LISP is directly implemented in the endpoint or when the endpoint 781 roams to an attached xTR. Each endpoint is then an xTR and the EID 782 address is the one presented to the network stack used by 783 applications while the RLOC is the address gathered from the network 784 when it is visited. 786 Whenever the device changes of RLOC, the xTR updates the RLOC of its 787 local mapping and registers it to its Map-Server. To avoid the need 788 of a home gateway, the ITR also indicates the RLOC change to all 789 remote devices that have ongoing communications with the device that 790 moved. The combination of both methods ensures the scalability of 791 the system as signaling is strictly limited the Map-Server and to 792 hosts with which communications are ongoing. 794 6. Multicast 796 LISP also supports transporting IP multicast packets sent from the 797 EID space, the operational changes required to the multicast 798 protocols are documented in [RFC6831]. 800 In such scenarios, LISP may create multicast state both at the core 801 and at the sites (both source and receiver). When signaling is used 802 to create multicast state at the sites, LISP routers unicast 803 encapsulate PIM Join/Prune messages from receiver to source sites. 804 At the core, ETRs build a new PIM Join/Prune message addressed to the 805 RLOC of the ITR servicing the source. An simplified sequence is 806 shown below 808 1. An end-host willing to join a multicast channel sends an IGMP 809 report. Multicast PIM routers at the LISP site propagate PIM 810 Join/Prune messages (S-EID, G) towards the ETR. 812 2. The join message flows to the ETR, upon reception the ETR builds 813 two join messages, the first one unicast LISP-encapsulates the 814 original join message towards the RLOC of the ITR servicing the 815 source. This message creates (S-EID, G) multicast state at the 816 source site. The second join message contains as destination 817 address the RLOC of the ITR servicing the source (S-RLOC, G) and 818 creates multicast state at the core. 820 3. Multicast data packets originated by the source (S-EID, G) flow 821 from the source to the ITR. The ITR LISP-encapsulates the 822 multicast packets, the outter header includes its own RLOC as the 823 source (S-RLOC) and the original multicast group address (G) as 824 the destination. Please note that multicast group address are 825 logical and are not resolved by the mapping system. Then the 826 multicast packet is transmitted through the core towards the 827 receiving ETRs that decapsulates the packets and sends them using 828 the receiver's site multicast state. 830 LISP can also support non-PIM mechanisms to maintain multicast state. 832 7. Security Considerations 834 LISP uses a pull architecture to learn mappings. While in a push 835 system, the state necessary to forward packets is learned 836 independently of the traffic itself, with a pull architecture, the 837 system becomes reactive and data-plane events (e.g., the arrival of a 838 packet for an unknown destination) may trigger control-plane events. 839 This on-demand learning of mappings provides many advantages as 840 discussed above but may also affect the way security is enforced. 842 Usually, the data-plane is implemented in the fast path of routers to 843 provide high performance forwarding capabilities while the control- 844 plane features are implemented in the slow path to offer high 845 flexibility and a performance gap of several order of magnitude can 846 be observed between the slow and the fast paths. As a consequence, 847 the way data-plane events are notified to the control-plane must be 848 thought carefully so to not overload the slow path and rate limiting 849 should be used as specified in [RFC6830]. 851 Care must also be taken so to not overload the mapping system (i.e., 852 the control plane infrastructure) as the operations to be performed 853 by the mapping system may be more complex than those on the data- 854 plane, for that reason [RFC6830] recommends to rate limit the sending 855 of messages to the mapping system. 857 To improve resiliency and reduce the overall number of messages 858 exchanged, LISP offers the possibility to leak information, such as 859 reachabilty of locators, directly into data plane packets. In 860 environments that are not fully trusted, control informations gleaned 861 from data-plane packets should be verified before using them. 863 Mappings are the centrepiece of LISP and all precautions must be 864 taken to avoid them to be manipulated or misused by malicious 865 entities. Using trustable Map-Servers that strictly respect 866 [RFC6833] and the lightweight authentication mechanism proposed by 867 LISP-Sec [I-D.ietf-lisp-sec] reduces the risk of attacks to the 868 mapping integrity. In more critical environments, secure measures 869 may be needed. 871 As with any other tunneling mechanism, middleboxes on the path 872 between an ITR (or PITR) and an ETR (or PETR) must implement 873 mechanisms to strip the LISP encapsulation to correctly inspect the 874 content of LISP encapsulated packets. 876 Like other map-and-encap mechanisms, LISP enables triangular routing 877 (i.e., packets of a flow cross different border routers depending on 878 their direction). This means that intermediate boxes may have 879 incomplete view on the traffic they inspect or manipulate. 881 More details about security implications of LISP are discussed in 882 [I-D.ietf-lisp-threats]. 884 8. Use Cases 886 8.1. Traffic Engineering 888 BGP is the standard protocol to implement inter-domain routing. With 889 BGP, routing informations are propagated along the network and each 890 autonomous system can implement its own routing policy that will 891 influence the way routing information are propagated. The direct 892 consequence is that an autonomous system cannot precisely control the 893 way the traffic will enter the network. 895 As opposed to BGP, a LISP site can strictly impose via which ETRs the 896 traffic must enter the the LISP site network even though the path 897 followed to reach the ETR is not under the control of the LISP site. 898 This fine control is implemented with the mappings. When a remote 899 site is willing to send traffic to a LISP site, it retrieves the 900 mapping associated to the destination EID via the mapping system. 901 The mapping is sent directly by an authoritative ETR of the EID and 902 is not altered by any intermediate network. 904 A mapping associates a list of RLOCs to an EID prefix. Each RLOC 905 corresponds to an interface of an ETR (or set of ETRs) that is able 906 to correctly forward packets to EIDs in the prefix. Each RLOC is 907 tagged with a priority and a weight in the mapping. The priority is 908 used to indicates which RLOCs should be preferred to send packets 909 (the least preferred ones being provided for backup purpose). The 910 weight permits to balance the load between the RLOCs with the same 911 priority, proportionally to the weight value. 913 As mappings are directly issued by the authoritative ETR of the EID 914 and are not altered while transmitted to the remote site, it offers 915 highly flexible incoming inter-domain traffic engineering with even 916 the possibility for a site to issue a different mapping for each 917 remote site, implementing so precise routing policies. 919 8.2. LISP for IPv6 Co-existence 921 LISP encapsulations allows to transport packets using EIDs from a 922 given address family (e.g., IPv6) with packets from other address 923 families (e.g., IPv4). The absence of correlation between the 924 address family of RLOCs and EIDs makes LISP a candidate to allow, 925 e.g., IPv6 to be deployed when all of the core network may not have 926 IPv6 enabled. 928 For example, two IPv6-only data centers could be interconnected via 929 the legacy IPv4 Internet. If their border routers are LISP capable, 930 sending packets between the data center is done without any form of 931 translation as the native IPv6 packets (in the EID space) will be 932 LISP encapsulated and transmitted over the IPv4 legacy Internet by 933 the mean of IPv4 RLOCs. 935 8.3. LISP for Virtual Private Networks 937 It is common to operate several virtual networks over the same 938 physical infrastructure. In such virtual private networks, it is 939 essential to distinguish which virtual network a packet belongs and 940 tags or labels are used for that purpose. When using LISP, the 941 distinction can be made with the Instance ID field. When an ITR 942 encapsulates a packet from a particular virtual network (e.g., known 943 via the VRF or VLAN), it tags the encapsulated packet with the 944 Instance ID corresponding to the virtual network of the packet. When 945 an ETR receives a packet tagged with an Instance ID it uses the 946 Instance ID to determine how to treat the packet. 948 The main usage of LISP for virtual private networks does not 949 introduce additional requirements on the underlying network, as long 950 as it is running IP. 952 8.4. LISP for Virtual Machine Mobility in Data Centers 954 A way to enable seamless virtual machine mobility in data center is 955 to conceive the datacenter backbone as the RLOC space and the subnet 956 where servers are hosted as forming the EID space. A LISP router is 957 placed at the border between the backbone and each subnet. When a 958 virtual machine is moved to another subnet, it can keep (temporarily) 959 the address it had before the move so to continue without a transport 960 layer connection reset. When an xTR detects a source address 961 received on a subnet to be an address not assigned to the subnet, it 962 registers the address to the Mapping System. 964 To inform the other LISP routers that the machine moved and where, 965 and then to avoid detours via the initial subnetwork, mechanisms such 966 as the Solicit-Map-Request messages are used. 968 9. Security Considerations 970 This document does not specify any protocol or operational practices 971 and hence, does not have any security considerations. 973 10. IANA Considerations 975 This memo includes no request to IANA. 977 11. Acknowledgements 979 This document was initiated by Noel Chiappa and much of the core 980 philosophy came from him. The authors acknowledge the important 981 contributions he has made to this work and thank him for his past 982 efforts. 984 The authors would also like to thank Dino Farinacci, Fabio Maino, 985 Luigi Iannone, Sharon Barakai, Isidoros Kouvelas, Christian Cassar, 986 Florin Coras, Marc Binderberger, Alberto Rodriguez-Natal, Ronald 987 Bonica, Chad Hintz, Robert Raszuk, Joel M. Halpern, Darrel Lewis, as 988 well as every people acknowledged in [RFC6830]. 990 12. References 992 12.1. Normative References 994 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 995 Requirement Levels", BCP 14, RFC 2119, March 1997. 997 [RFC3232] Reynolds, J., "Assigned Numbers: RFC 1700 is Replaced by 998 an On-line Database", RFC 3232, January 2002. 1000 [RFC4116] Abley, J., Lindqvist, K., Davies, E., Black, B., and V. 1001 Gill, "IPv4 Multihoming Practices and Limitations", RFC 1002 4116, July 2005. 1004 [RFC4984] Meyer, D., Zhang, L., and K. Fall, "Report from the IAB 1005 Workshop on Routing and Addressing", RFC 4984, September 1006 2007. 1008 [RFC6830] Farinacci, D., Fuller, V., Meyer, D., and D. Lewis, "The 1009 Locator/ID Separation Protocol (LISP)", RFC 6830, January 1010 2013. 1012 [RFC6831] Farinacci, D., Meyer, D., Zwiebel, J., and S. Venaas, "The 1013 Locator/ID Separation Protocol (LISP) for Multicast 1014 Environments", RFC 6831, January 2013. 1016 [RFC6832] Lewis, D., Meyer, D., Farinacci, D., and V. Fuller, 1017 "Interworking between Locator/ID Separation Protocol 1018 (LISP) and Non-LISP Sites", RFC 6832, January 2013. 1020 [RFC6833] Fuller, V. and D. Farinacci, "Locator/ID Separation 1021 Protocol (LISP) Map-Server Interface", RFC 6833, January 1022 2013. 1024 [RFC6834] Iannone, L., Saucez, D., and O. Bonaventure, "Locator/ID 1025 Separation Protocol (LISP) Map-Versioning", RFC 6834, 1026 January 2013. 1028 [RFC6835] Farinacci, D. and D. Meyer, "The Locator/ID Separation 1029 Protocol Internet Groper (LIG)", RFC 6835, January 2013. 1031 [RFC6836] Fuller, V., Farinacci, D., Meyer, D., and D. Lewis, 1032 "Locator/ID Separation Protocol Alternative Logical 1033 Topology (LISP+ALT)", RFC 6836, January 2013. 1035 [RFC6837] Lear, E., "NERD: A Not-so-novel Endpoint ID (EID) to 1036 Routing Locator (RLOC) Database", RFC 6837, January 2013. 1038 [RFC6935] Eubanks, M., Chimento, P., and M. Westerlund, "IPv6 and 1039 UDP Checksums for Tunneled Packets", RFC 6935, April 2013. 1041 [RFC6936] Fairhurst, G. and M. Westerlund, "Applicability Statement 1042 for the Use of IPv6 UDP Datagrams with Zero Checksums", 1043 RFC 6936, April 2013. 1045 [RFC7052] Schudel, G., Jain, A., and V. Moreno, "Locator/ID 1046 Separation Protocol (LISP) MIB", RFC 7052, October 2013. 1048 [RFC7215] Jakab, L., Cabellos-Aparicio, A., Coras, F., Domingo- 1049 Pascual, J., and D. Lewis, "Locator/Identifier Separation 1050 Protocol (LISP) Network Element Deployment 1051 Considerations", RFC 7215, April 2014. 1053 12.2. Informative References 1055 [Chiappa] Chiappa, J., "Endpoints and Endpoint names: A Propose 1056 Enhancement to the Internet Architecture, 1057 http://mercury.lcs.mit.edu/~jnc/tech/endpoints.txt", 1999. 1059 [DDT-ROOT] 1060 LISP DDT ROOT, , "http://ddt-root.org/", August 2013. 1062 [DFZ] Huston, Geoff., "Growth of the BGP Table - 1994 to Present 1063 http://bgp.potaroo.net/", August 2013. 1065 [I-D.cheng-lisp-shdht] 1066 Cheng, L. and J. Wang, "LISP Single-Hop DHT Mapping 1067 Overlay", draft-cheng-lisp-shdht-04 (work in progress), 1068 July 2013. 1070 [I-D.curran-lisp-emacs] 1071 Brim, S., Farinacci, D., Meyer, D., and J. Curran, "EID 1072 Mappings Multicast Across Cooperating Systems for LISP", 1073 draft-curran-lisp-emacs-00 (work in progress), November 1074 2007. 1076 [I-D.ietf-lisp-ddt] 1077 Fuller, V., Lewis, D., Ermagan, V., and A. Jain, "LISP 1078 Delegated Database Tree", draft-ietf-lisp-ddt-02 (work in 1079 progress), October 2014. 1081 [I-D.ietf-lisp-lcaf] 1082 Farinacci, D., Meyer, D., and J. Snijders, "LISP Canonical 1083 Address Format (LCAF)", draft-ietf-lisp-lcaf-06 (work in 1084 progress), October 2014. 1086 [I-D.ietf-lisp-sec] 1087 Maino, F., Ermagan, V., Cabellos-Aparicio, A., and D. 1088 Saucez, "LISP-Security (LISP-SEC)", draft-ietf-lisp-sec-07 1089 (work in progress), October 2014. 1091 [I-D.ietf-lisp-threats] 1092 Saucez, D., Iannone, L., and O. Bonaventure, "LISP Threats 1093 Analysis", draft-ietf-lisp-threats-10 (work in progress), 1094 July 2014. 1096 [I-D.mathy-lisp-dht] 1097 Mathy, L., Iannone, L., and O. Bonaventure, ""LISP-DHT: 1098 Towards a DHT to map identifiers onto locators" draft- 1099 mathy-lisp-dht-00 (work in progress)", April 2008. 1101 [Jakab] Jakab, L., Cabellos, A., Saucez, D., and O. Bonaventure, 1102 "LISP-TREE: A DNS Hierarchy to Support the LISP Mapping 1103 System, IEEE Journal on Selected Areas in Communications, 1104 vol. 28, no. 8, pp. 1332-1343", October 2010. 1106 [Quoitin] Quoitin, B., Iannone, L., Launois, C., and O. Bonaventure, 1107 ""Evaluating the Benefits of the Locator/Identifier 1108 Separation" in Proceedings of 2Nd ACM/IEEE International 1109 Workshop on Mobility in the Evolving Internet 1110 Architecture", 2007. 1112 Appendix A. A Brief History of Location/Identity Separation 1114 The LISP system for separation of location and identity resulted from 1115 the discussions of this topic at the Amsterdam IAB Routing and 1116 Addressing Workshop, which took place in October 2006 [RFC4984]. 1118 A small group of like-minded personnel from various scattered 1119 locations within Cisco, spontaneously formed immediately after that 1120 workshop, to work on an idea that came out of informal discussions at 1121 the workshop and on various mailing lists. The first Internet-Draft 1122 on LISP appeared in January, 2007. 1124 Trial implementations started at that time, with initial trial 1125 deployments underway since June 2007; the results of early experience 1126 have been fed back into the design in a continuous, ongoing process 1127 over several years. LISP at this point represents a moderately 1128 mature system, having undergone a long organic series of changes and 1129 updates. 1131 LISP transitioned from an IRTF activity to an IETF WG in March 2009, 1132 and after numerous revisions, the basic specifications moved to 1133 becoming RFCs at the start of 2013 (although work to expand and 1134 improve it, and find new uses for it, continues, and undoubtly will 1135 for a long time to come). 1137 A.1. Old LISP Models 1139 LISP, as initially conceived, had a number of potential operating 1140 modes, named 'models'. Although they are note used anymore, one 1141 occasionally sees mention of them, so they are briefly described 1142 here. 1144 LISP 1: EIDs all appear in the normal routing and forwarding tables 1145 of the network (i.e. they are 'routable');this property is used to 1146 'bootstrap' operation, by using this to load EID->RLOC mappings. 1147 Packets were sent with the EID as the destination in the outer 1148 wrapper; when an ETR saw such a packet, it would send a Map-Reply 1149 to the source ITR, giving the full mapping. 1151 LISP 1.5: Similar to LISP 1, but the routability of EIDs happens on 1152 a separate network. 1154 LISP 2: EIDs are not routable; EID->RLOC mappings are available from 1155 the DNS. 1157 LISP 3: EIDs are not routable; and have to be looked up in in a new 1158 EID->RLOC mapping database (in the initial concept, a system using 1159 Distributed Hash Tables). Two variants were possible: a 'push' 1160 system, in which all mappings were distributed to all ITRs, and a 1161 'pull' system in which ITRs load the mappings they need, as 1162 needed. 1164 Authors' Addresses 1166 Albert Cabellos 1167 UPC-BarcelonaTech 1168 c/ Jordi Girona 1-3 1169 Barcelona, Catalonia 08034 1170 Spain 1172 Email: acabello@ac.upc.edu 1174 Damien Saucez (Ed.) 1175 INRIA 1176 2004 route des Lucioles BP 93 1177 Sophia Antipolis Cedex 06902 1178 France 1180 Email: damien.saucez@inria.fr