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Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (September 8, 2011) is 4614 days in the past. Is this intentional? Checking references for intended status: Experimental ---------------------------------------------------------------------------- == Outdated reference: A later version (-24) exists of draft-ietf-lisp-15 == Outdated reference: A later version (-16) exists of draft-ietf-lisp-ms-11 == Outdated reference: A later version (-06) exists of draft-ietf-lisp-interworking-02 Summary: 0 errors (**), 0 flaws (~~), 5 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group V. Fuller 3 Internet-Draft D. Farinacci 4 Intended status: Experimental D. Meyer 5 Expires: March 11, 2012 D. Lewis 6 Cisco 7 September 8, 2011 9 LISP Alternative Topology (LISP+ALT) 10 draft-ietf-lisp-alt-08.txt 12 Abstract 14 This document describes a simple distributed index system to be used 15 by a Locator/ID Separation Protocol (LISP) Ingress Tunnel Router 16 (ITR) or Map Resolver (MR) to find the Egress Tunnel Router (ETR) 17 which holds the mapping information for a particular Endpoint 18 Identifier (EID). The MR can then query that ETR to obtain the 19 actual mapping information, which consists of a list of Routing 20 Locators (RLOCs) for the EID. Termed the Alternative Logical 21 Topology (ALT), the index is built as an overlay network on the 22 public Internet using the Border Gateway Protocol (BGP) and the 23 Generic Routing Encapsulation (GRE). Using these proven protocols, 24 the ALT can be built and deployed relatively quickly without any 25 changes to the existing routing infrastructure. 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 March 11, 2012. 44 Copyright Notice 46 Copyright (c) 2011 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 . . . . . . . . . . . . . . . . . . . . . . . . . 4 62 2. Definition of Terms . . . . . . . . . . . . . . . . . . . . . 6 63 3. The LISP+ALT model . . . . . . . . . . . . . . . . . . . . . . 9 64 3.1. Routeability of EIDs . . . . . . . . . . . . . . . . . . . 9 65 3.1.1. Mechanisms for an ETR to originate EID-prefixes . . . 10 66 3.1.2. Mechanisms for an ITR to forward to EID-prefixes . . . 10 67 3.1.3. Map Server Model preferred . . . . . . . . . . . . . . 10 68 3.2. Connectivity to non-LISP sites . . . . . . . . . . . . . . 10 69 3.3. Caveats on the use of Data Probes . . . . . . . . . . . . 11 70 4. LISP+ALT: Overview . . . . . . . . . . . . . . . . . . . . . . 12 71 4.1. ITR traffic handling . . . . . . . . . . . . . . . . . . . 13 72 4.2. EID Assignment - Hierarchy and Topology . . . . . . . . . 13 73 4.3. Use of GRE and BGP between LISP+ALT Routers . . . . . . . 15 74 5. EID-prefix Propagation and Map-Request Forwarding . . . . . . 16 75 5.1. Changes to ITR behavior with LISP+ALT . . . . . . . . . . 16 76 5.2. Changes to ETR behavior with LISP+ALT . . . . . . . . . . 17 77 6. BGP configuration and protocol considerations . . . . . . . . 18 78 6.1. Autonomous System Numbers (ASNs) in LISP+ALT . . . . . . . 18 79 6.2. Sub-Address Family Identifier (SAFI) for LISP+ALT . . . . 18 80 7. EID-prefix Aggregation . . . . . . . . . . . . . . . . . . . . 19 81 7.1. Stability of the ALT . . . . . . . . . . . . . . . . . . . 19 82 7.2. Traffic engineering using LISP . . . . . . . . . . . . . . 19 83 7.3. Edge aggregation and dampening . . . . . . . . . . . . . . 20 84 7.4. EID assignment flexibility vs. ALT scaling . . . . . . . . 20 85 8. Connecting sites to the ALT network . . . . . . . . . . . . . 22 86 8.1. ETRs originating information into the ALT . . . . . . . . 22 87 8.2. ITRs Using the ALT . . . . . . . . . . . . . . . . . . . . 22 88 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24 89 10. Security Considerations . . . . . . . . . . . . . . . . . . . 25 90 10.1. Apparent LISP+ALT Vulnerabilities . . . . . . . . . . . . 25 91 10.2. Survey of LISP+ALT Security Mechanisms . . . . . . . . . . 26 92 10.3. Use of new IETF standard BGP Security mechanisms . . . . . 26 93 11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 27 94 12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 28 95 12.1. Normative References . . . . . . . . . . . . . . . . . . . 28 96 12.2. Informative References . . . . . . . . . . . . . . . . . . 28 97 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 29 99 1. Introduction 101 This document describes the LISP+ALT system, used by a [LISP] ITR or 102 MR to find the ETR that holds the RLOC mapping information for a 103 particular EID. The ALT network is built using the Border Gateway 104 Protocol (BGP, [RFC4271]), the BGP multi-protocol extension 105 [RFC4760], and the Generic Routing Encapsulation (GRE, [RFC2784]) to 106 construct an overlay network of devices (ALT Routers) which operate 107 on EID-prefixes and use EIDs as forwarding destinations. 109 ALT Routers advertise hierarchically-delegated segments of the EID 110 namespace (i.e., prefixes) toward the rest of the ALT; they also 111 forward traffic destined for an EID covered by one of those prefixes 112 toward the network element that is authoritative for that EID and is 113 the origin of the BGP advertisement for that EID-prefix. An Ingress 114 Tunnel Router (ITR) uses this overlay to send a LISP Map-Request 115 (defined in [LISP]) to the Egress Tunnel Router (ETR) that holds the 116 EID-to-RLOC mapping for a matching EID-prefix. In most cases, an ITR 117 does not connect directly to the overlay network but instead sends 118 Map-Requests via a Map-Resolver (described in [LISP-MS]) which does. 119 Likewise, in most cases, an ETR does not connect directly to the 120 overlay network but instead registers its EID-prefixes with a Map- 121 Server that advertises those EID-prefixes on to the ALT and forwards 122 Map-Requests for them to the ETR. 124 It is important to note that the ALT does not distribute actual EID- 125 to-RLOC mappings. What it does provide is a forwarding path from an 126 ITR (or MR) which requires an EID-to-RLOC mapping to an ETR which 127 holds that mapping. The ITR/MR uses this path to send an ALT 128 Datagram (see Section 3) to an ETR which then responds with a Map- 129 Reply containing the needed mapping information. 131 One design goal for LISP+ALT is to use existing technology wherever 132 possible. To this end, the ALT is intended to be built using off- 133 the-shelf routers which already implement the required protocols (BGP 134 and GRE); little, if any, LISP-specific modifications should be 135 needed for such devices to be deployed on the ALT (see Section 7 for 136 aggregation requirements). Note, though, that organizational and 137 operational considerations suggest that ALT Routers be both logically 138 and physically separate from the "native" Internet packet transport 139 system; deploying this overlay on those routers which are already 140 participating in the global routing system and actively forwarding 141 Internet traffic is not recommended. 143 This specification is experimental, and there are areas where further 144 experience is needed to understand the best implementation strategy, 145 operational model, and effects on Internet operations. These areas 146 include: 148 o application effects of on-demand route map discovery 150 o tradeoff in connection setup time vs. ALT design and performance 151 when using a Map Request instead of carring initial user data in a 152 Data Probe 154 o best practical ways to build ALT hierarchies 156 o effects of route leakage from ALT to the current Internet, 157 particularly for LISP-to-non-LISP interworking 159 o effects of exceptional situations, such as denial-of-service 160 attacks 162 Experimentation, measurements, and deployment experience on these 163 aspects is appreciated. While these issues are conceptually well- 164 understood (e.g. an ALT lookup causes potential delay for the first 165 packet destined to a given network), the real-world operational 166 effects are much less clear. 168 The remainder of this document is organized as follows: Section 2 169 provides the definitions of terms used in this document. Section 3 170 outlines the LISP ALT model, where EID prefixes are routed across an 171 overlay network. Section 4 provides a basic overview of the LISP 172 Alternate Topology architecture, and Section 5 describes how the ALT 173 uses BGP to propagate Endpoint Identifier reachability over the 174 overlay network and Section 6 describes other considerations for 175 using BGP on the ALT. Section 7 describes the construction of the 176 ALT aggregation hierarchy, and Section 8 discusses how LISP+ALT 177 elements are connected to form the overlay network. 179 2. Definition of Terms 181 This section provides high-level definitions of LISP concepts and 182 components involved with and affected by LISP+ALT. 184 Alternative Logical Topology (ALT): The virtual overlay network 185 made up of tunnels between LISP+ALT Routers. The Border Gateway 186 Protocol (BGP) runs between ALT Routers and is used to carry 187 reachability information for EID-prefixes. The ALT provides a way 188 to forward Map-Requests (and, if supported, Data Probes) toward 189 the ETR that "owns" an EID-prefix. As a tunneled overlay, its 190 performance is expected to be quite limited so use of it to 191 forward high-bandwidth flows of Data Probes is strongly 192 discouraged (see Section 3.3 for additional discussion). 194 Legacy Internet: The portion of the Internet which does not run 195 LISP and does not participate in LISP+ALT. 197 ALT Router: The devices which run on the ALT. The ALT is a static 198 network built using tunnels between ALT Routers. These routers 199 are deployed in a roughly-hierarchical mesh in which routers at 200 each level in the topology are responsible for aggregating EID- 201 prefixes learned from those logically "below" them and advertising 202 summary prefixes to those logically "above" them. Prefix learning 203 and propagation between ALT Routers is done using BGP. An ALT 204 Router at the lowest level, or "edge" of the ALT, learns EID- 205 prefixes from its "client" ETRs. See Section 3.1 for a 206 description of how EID-prefixes are learned at the "edge" of the 207 ALT. See also Section 6 for details on how BGP is configured 208 between the different network elements. When an ALT Router 209 receives an ALT Datagram, it looks up the destination EID in its 210 forwarding table (composed of EID prefix routes it learned from 211 neighboring ALT Routers) and forwards it to the logical next-hop 212 on the overlay network. 214 Endpoint ID (EID): A 32-bit (for IPv4) or 128-bit (for ipv6) value 215 used to identify the ultimate source or destination for a LISP- 216 encapsulated packet. See [LISP] for details. 218 EID-prefix: A set of EIDs delegated in a power-of-two block. EID- 219 prefixes are routed on the ALT (not on the global Internet) and 220 are expected to be assigned in a hierarchical manner such that 221 they can be aggregated by ALT Routers. Such a block is 222 characterized by a prefix and a length. Note that while the ALT 223 routing system considers an EID-prefix to be an opaque block of 224 EIDs, an end site may put site-local, topologically-relevant 225 structure (subnetting) into an EID-prefix for intra-site routing. 227 Aggregated EID-prefixes: A set of individual EID-prefixes that have 228 been aggregated in the [RFC4632] sense. 230 Map Server (MS): An edge ALT Router that provides a registration 231 function for non-ALT-connected ETRs, originates EID-prefixes into 232 the ALT on behalf of those ETRs, and forwards Map-Requests to 233 them. See [LISP-MS] for details. 235 Map Resolver (MR): An edge ALT Router that accepts an Encapsulated 236 Map-Request from a non-ALT-connected ITR, decapsulates it, and 237 forwards it on to the ALT toward the ETR which owns the requested 238 EID-prefix. See [LISP-MS] for details. 240 Ingress Tunnel Router (ITR): A router which sends LISP Map- 241 Requests or encapsulates IP datagrams with LISP headers, as 242 defined in [LISP]. In this document, the term refers to any 243 device implementing ITR functionality, including a Proxy-ITR (see 244 [LISP-IW]). Under some circumstances, a LISP Map Resolver may 245 also originate Map-Requests (see [LISP-MS]). 247 Egress Tunnel Router (ETR): A router which sends LISP Map-Replies 248 in response to LISP Map-Requests and decapsulates LISP- 249 encapsulated IP datagrams for delivery to end systems, as defined 250 in [LISP]. In this document, the term refers to any device 251 implementing ETR functionality, including a Proxy-ETR (see 252 [LISP-IW]). Under some circumstances, a LISP Map Server may also 253 respond to Map-Requests (see [LISP-MS]). 255 Routing Locator (RLOC): A routable IP address for a LISP tunnel 256 router (ITR or ETR). Interchangeably referred to as a "locator" 257 in this document. An RLOC is also the output of an EID-to-RLOC 258 mapping lookup; an EID-prefix maps to one or more RLOCs. 259 Typically, RLOCs are numbered from topologically-aggregatable 260 blocks that are assigned to a site at each point where it attaches 261 to the global Internet; where the topology is defined by the 262 connectivity of provider networks, RLOCs can be thought of as 263 Provider Aggregatable (PA) addresses. Routing for RLOCs is not 264 carried on the ALT. 266 EID-to-RLOC Mapping: A binding between an EID-prefix and the set of 267 RLOCs that can be used to reach it; sometimes referred to simply 268 as a "mapping". 270 EID-prefix Reachability: An EID-prefix is said to be "reachable" if 271 at least one of its locators is reachable. That is, an EID-prefix 272 is reachable if the ETR that is authoritative for a given EID-to- 273 RLOC mapping is reachable. 275 Default Mapping: A Default Mapping is a mapping entry for EID- 276 prefix 0.0.0.0/0 (0::/0 for ipv6). It maps to a locator-set used 277 for all EIDs in the Internet. If there is a more specific EID- 278 prefix in the mapping cache it overrides the Default Mapping 279 entry. The Default Mapping can be learned by configuration or 280 from a Map-Reply message. 282 ALT Default Route: An EID-prefix value of 0.0.0.0/0 (or 0::/0 for 283 ipv6) which may be learned from the ALT or statically configured 284 on an edge ALT Router. The ALT-Default Route defines a forwarding 285 path for a packet to be sent into the ALT on a router which does 286 not have a full ALT forwarding database. 288 3. The LISP+ALT model 290 The LISP+ALT model uses the same basic query/response protocol that 291 is documented in [LISP]. In particular, LISP+ALT provides two types 292 of packet that an ITR can originate to obtain EID-to-RLOC mappings: 294 Map-Request: A Map-Request message is sent into the ALT to request 295 an EID-to-RLOC mapping. The ETR which owns the mapping will 296 respond to the ITR with a Map-Reply message. Since the ALT only 297 forwards on EID destinations, the destination address of the Map- 298 Request sent on the ALT must be an EID. 300 Data Probe: Alternatively, an ITR may encapsulate and send the first 301 data packet destined for an EID with no known RLOCs into the ALT 302 as a Data Probe. This might be done to minimize packet loss and 303 to probe for the mapping. As above, the authoritative ETR for the 304 EID-prefix will respond to the ITR with a Map-Reply message when 305 it receives the data packet over the ALT. As a side-effect, the 306 encapsulated data packet is delivered to the end-system at the ETR 307 site. Note that the Data Probe's inner IP destination address, 308 which is an EID, is copied to the outer IP destination address so 309 that the resulting packet can be routed over the ALT. See 310 Section 3.3 for caveats on the usability of Data Probes. 312 The term "ALT Datagram" is short-hand for a Map-Request or Data Probe 313 to be sent into or forwarded on the ALT. Note that such packets use 314 an RLOC as the outer header source IP address and an EID as the outer 315 header destination IP address. 317 Detailed descriptions of the LISP packet types referenced by this 318 document may be found in [LISP]. 320 3.1. Routeability of EIDs 322 A LISP EID has the same syntax as IP address and can be used, 323 unaltered, as the source or destination of an IP datagram. In 324 general, though, EIDs are not routable on the public Internet; LISP+ 325 ALT provides a separate, virtual network, known as the LISP 326 Alternative Logical Topology (ALT) on which a datagram using an EID 327 as an IP destination address may be transmitted. This network is 328 built as an overlay on the public Internet using tunnels to 329 interconnect ALT Routers. BGP runs over these tunnels to propagate 330 path information needed to forward ALT Datagrams. Importantly, while 331 the ETRs are the source(s) of the unaggregated EID-prefixes, LISP+ALT 332 uses existing BGP mechanisms to aggregate this information. 334 3.1.1. Mechanisms for an ETR to originate EID-prefixes 336 There are three ways that an ETR may originate its mappings into the 337 ALT: 339 1. By registration with a Map Server as documented in [LISP-MS]. 340 This is the common case and is expected to be used by the 341 majority of ETRs. 343 2. Using a "static route" on the ALT. Where no Map-Server is 344 available, an edge ALT Router may be configured with a "static 345 EID-prefix route" pointing to an ETR. 347 3. Edge connection to the ALT. If a site requires fine- grained 348 control over how its EID-prefixes are advertised into the ALT, it 349 may configure its ETR(s) with tunnel and BGP connections to edge 350 ALT Routers. 352 3.1.2. Mechanisms for an ITR to forward to EID-prefixes 354 There are three ways that an ITR may send ALT Datagrams: 356 1. Through a Map Resolver as documented in [LISP-MS]. This is the 357 common case and is expected to be used by the majority of ITRs. 359 2. Using a "default route". Where a Map Resolver is not available, 360 an ITR may be configured with a static ALT Default Route pointing 361 to an edge ALT Router. 363 3. Edge connection to the ALT. If a site requires fine-grained 364 knowledge of what prefixes exist on the ALT, it may configure its 365 ITR(s) with tunnel and BGP connections to edge ALT Routers. 367 3.1.3. Map Server Model preferred 369 The ALT-connected ITR and ETR cases are expected to be rare, as the 370 Map Server/Map Resolver model is both simpler for an ITR/ETR operator 371 to use, and provides a more general service interface to not only the 372 ALT, but also to other mapping databases that may be developed in the 373 future. 375 3.2. Connectivity to non-LISP sites 377 As stated above, EIDs used as IP addresses by LISP sites are not 378 routable on the public Internet. This implies that, absent a 379 mechanism for communication between LISP and non-LISP sites, 380 connectivity between them is not possible. To resolve this problem, 381 an "interworking" technology has been defined; see [LISP-IW] for 382 details. 384 3.3. Caveats on the use of Data Probes 386 It is worth noting that there has been a great deal of discussion and 387 controversy about whether Data Probes are a good idea. On the one 388 hand, using them offers a method of avoiding the "first packet drop" 389 problem when an ITR does not have a mapping for a particular EID- 390 prefix. On the other hand, forwarding data packets on the ALT would 391 require that it either be engineered to support relatively high 392 traffic rates, which is not generally feasible for a tunneled 393 network, or that it be carefully designed to aggressively rate-limit 394 traffic to avoid congestion or DoS attacks. There may also be issues 395 caused by different latency or other performance characteristics 396 between the ALT path taken by an initial Data Probe and the 397 "Internet" path taken by subsequent packets on the same flow once a 398 mapping is in place on an ITR. For these reasons, the use of Data 399 Probes is not recommended at this time; they should only be 400 originated an ITR when explicitly configured to do so and such 401 configuration should only be enabled when performing experiments 402 intended to test the viability of using Data Probes. 404 4. LISP+ALT: Overview 406 LISP+ALT is a hybrid push/pull architecture. Aggregated EID-prefixes 407 are advertised among the ALT Routers and to those (rare) ITRs that 408 are directly connected via a tunnel and BGP to the ALT. Specific 409 EID-to-RLOC mappings are requested by an ITR (and returned by an ETR) 410 using LISP when it sends a request either via a Map Resolver or to an 411 edge ALT Router. 413 The basic idea embodied in LISP+ALT is to use BGP, running on a 414 tunneled overlay network (the ALT), to establish reachability between 415 ALT Routers. The ALT BGP Route Information Base (RIB) is comprised 416 of EID-prefixes and associated next hops. ALT Routers interconnect 417 using BGP and propagate EID-prefix updates among themselves. EID- 418 prefix information is learned from ETRs at the "edge" of the ALT 419 either through the use of the Map Server interface (the commmon 420 case), static configuration, or by BGP-speaking ETRs. 422 An ITR uses the ALT to learn the best path for forwarding an ALT 423 Datagram destined to a particular EID-prefix. An ITR will normally 424 use a Map Resolver to send its ALT Datagrams on to the ALT but may, 425 in unusual circumstances, use a static ALT Default Route or connect 426 to the ALT using BGP. 428 Note that while this document specifies the use of Generic Routing 429 Encapsulation (GRE) as a tunneling mechanism, there is no reason that 430 parts of the ALT cannot be built using other tunneling technologies, 431 particularly in cases where GRE does not meet security, management, 432 or other operational requirements. References to "GRE tunnel" in 433 later sections of this document should therefore not be taken as 434 prohibiting or precluding the use of other tunneling mechanisms. 435 Note also that two ALT Routers that are directly adjacent (with no 436 layer-3 router hops between them) need not use a tunnel between them; 437 in this case, BGP may be configured across the interfaces that 438 connect to their common subnet and that subnet is then considered to 439 be part of the ALT topology. Use of techniques such as "eBGP 440 multihop" to connect ALT Routers that do not share a tunnel or common 441 subnet is not recommended as the non-ALT Routers in between the ALT 442 Routers in such a configuration may not have information necessary to 443 forward ALT Datagrams destined to EID-prefixes exchanged across that 444 BGP session. 446 In summary, LISP+ALT uses BGP to build paths through ALT Routers so 447 that an ALT Datagram sent into the ALT can be forwarded to the ETR 448 that holds the EID-to-RLOC mapping for that EID-prefix. This 449 reachability is carried as IPv4 or ipv6 NLRI without modification 450 (since an EID-prefix has the same syntax as IPv4 or ipv6 address 451 prefix). ALT Routers establish BGP sessions with one another, 452 forming the ALT. An ALT Router at the "edge" of the topology learns 453 EID-prefixes originated by authoritative ETRs. Learning may be 454 though the Map Server interface, by static configuration, or via BGP 455 with the ETRs. An ALT Router may also be configured to aggregate 456 EID-prefixes received from ETRs or from other LISP+ALT routers that 457 are topologically "downstream" from it. 459 4.1. ITR traffic handling 461 When an ITR receives a packet originated by an end system within its 462 site (i.e. a host for which the ITR is the exit path out of the site) 463 and the destination EID for that packet is not known in the ITR's 464 mapping cache, the ITR creates either a Map-Request for the 465 destination EID or the original packet encapsulated as a Data Probe 466 (see Section 3.3 for caveats on the usability of Data Probes). The 467 result, known as an ALT Datagram, is then sent to an ALT Router (see 468 also [LISP-MS] for non-ALT-connected ITRs, noting that Data Probes 469 cannot be sent to a Map-Resolver). This "first hop" ALT Router uses 470 EID-prefix routing information learned from other ALT Routers via BGP 471 to guide the packet to the ETR which "owns" the prefix. Upon receipt 472 by the ETR, normal LISP processing occurs: the ETR responds to the 473 ITR with a LISP Map-Reply that lists the RLOCs (and, thus, the ETRs 474 to use) for the EID-prefix. For Data Probes, the ETR also 475 decapsulates the packet and transmits it toward its destination. 477 Upon receipt of the Map-Reply, the ITR installs the RLOC information 478 for a given prefix into a local mapping database. With these mapping 479 entries stored, additional packets destined to the given EID-prefix 480 are routed directly to an RLOC without use of the ALT, until either 481 the entry's TTL has expired, or the ITR can otherwise find no 482 reachable ETR. Note that a current mapping may exist that contains 483 no reachable RLOCs; this is known as a Negative Cache Entry and it 484 indicates that packets destined to the EID-prefix are to be dropped. 486 Full details on Map-Request/Map-Reply processing may be found in 487 [LISP]. 489 Traffic routed on to the ALT consists solely of ALT Datagrams, i.e. 490 Map-Requests and Data Probes (if supported). Given the relatively 491 low performance expected of a tunneled topology, ALT Routers (and Map 492 Resolvers) should aggressively rate-limit the ingress of ALT 493 Datagrams from ITRs and, if possible, should be configured to not 494 accept packets that are not ALT Datagrams. 496 4.2. EID Assignment - Hierarchy and Topology 498 EID-prefixes are expected to be allocated to a LISP site by Internet 499 Registries. Where a site has multiple allocations which are aligned 500 on a power-of-2 block boundary, they should be aggregated into a 501 single EID-prefix for advertisement. The ALT network is built in a 502 roughly hierarchical, partial mesh which is intended to allow 503 aggregation where clearly-defined hierarchical boundaries exist. 504 Building such a structure should minimize the number of EID-prefixes 505 carried by LISP+ALT nodes near the top of the hierarchy. 507 Routes on the ALT do not need to respond to changes in policy, 508 subscription, or underlying physical connectivity, so the topology 509 can remain relatively static and aggregation can be sustained. 510 Because routing on the ALT uses BGP, the same rules apply for 511 generating aggregates; in particular, a ALT Router should only be 512 configured to generate an aggregate if it is configured with BGP 513 sessions to all of the originators of components (more-specific 514 prefixes) of that aggregate. Not all of the components of need to be 515 present for the aggregate to be originated (some may be holes in the 516 covering prefix and some may be down) but the aggregating router must 517 be configured to learn the state of all of the components. 519 Under what circumstances the ALT Router actually generates the 520 aggregate is a matter of local policy: in some cases, it will be 521 statically configured to do so at all times with a "static discard" 522 route. In other cases, it may be configured to only generate the 523 aggregate prefix if at least one of the components of the aggregate 524 is learned via BGP. 526 An ALT Router must not generate an aggregate that includes a non- 527 LISP-speaking hole unless it can be configured to return a Negative 528 Map-Reply with action="Natively-Forward" (see [LISP]) if it receives 529 an ALT Datagram that matches that hole. If it receives an ALT 530 Datagram that matches a LISP-speaking hole that is currently not 531 reachable, it should return a Negative Map-Reply with action="drop". 532 Negative Map-Replies should be returned with a short TTL, as 533 specified in [LISP-MS]. Note that an off-the-shelf, non-LISP- 534 speaking router configured as an aggregating ALT Router cannot send 535 Negative Map-Replies, so such a router must never originate an 536 aggregate that includes a non-LISP-speaking hole. 538 This implies that two ALT Routers that share an overlapping set of 539 prefixes must exchange those prefixes if either is to generate and 540 export a covering aggregate for those prefixes. It also implies that 541 an ETR which connects to the ALT using BGP must maintain BGP sessions 542 with all of the ALT Routers that are configured to originate an 543 aggregate which covers that prefix and that each of those ALT Routers 544 must be explicitly configured to know the set of EID-prefixes that 545 make up any aggregate that it originates. See also [LISP-MS] for an 546 example of other ways that prefix origin consistency and aggregation 547 can be maintained. 549 As an example, consider ETRs that are originating EID-prefixes for 550 10.1.0.0/24, 10.1.64.0/24, 10.1.128.0/24, and 10.1.192.0/24. An ALT 551 Router should only be configured to generate an aggregate for 552 10.1.0.0/16 if it has BGP sessions configured with all of these ETRs, 553 in other words, only if it has sufficient knowledge about the state 554 of those prefixes to summarize them. If the Router originating 555 10.1.0.0/16 receives an ALT Datagram destined for 10.1.77.88, a non- 556 LISP destination covered by the aggregate, it returns a Negative Map- 557 Reply with action "Natively-Forward". If it receives an ALT Datagram 558 destined for 10.1.128.199 but the configured LISP prefix 559 10.1.128.0/24 is unreachable, it returns a Negative Map-Reply with 560 action "drop". 562 Note: much is currently uncertain about the best way to build the ALT 563 network; as testing and prototype deployment proceeds, a guide to how 564 to best build the ALT network will be developed. 566 4.3. Use of GRE and BGP between LISP+ALT Routers 568 The ALT network is built using GRE tunnels between ALT Routers. BGP 569 sessions are configured over those tunnels, with each ALT Router 570 acting as a separate AS "hop" in a Path Vector for BGP. For the 571 purposes of LISP+ALT, the AS-path is used solely as a shortest-path 572 determination and loop-avoidance mechanism. Because all next-hops 573 are on tunnel interfaces, no IGP is required to resolve those next- 574 hops to exit interfaces. 576 LISP+ALT's use of GRE and BGP facilities deployment and operation of 577 LISP because no new protocols need to be defined, implemented, or 578 used on the overlay topology; existing BGP/GRE tools and operational 579 expertise are also re-used. Tunnel address assignment is also easy: 580 since the addresses on an ALT tunnel are only used by the pair of 581 routers connected to the tunnel, the only requirement of the IP 582 addresses used to establish that tunnel is that the attached routers 583 be reachable by each other; any addressing plan, including private 584 addressing, can therefore be used for ALT tunnels. 586 5. EID-prefix Propagation and Map-Request Forwarding 588 As described in Section 8.2, an ITR sends an ALT Datagram to a given 589 EID-to-RLOC mapping. The ALT provides the infrastructure that allows 590 these requests to reach the authoritative ETR. 592 Note that under normal circumstances Map-Replies are not sent over 593 the ALT; an ETR sends a Map-Reply to one of the ITR RLOCs learned 594 from the original Map-Request. See sections 6.1.2 and 6.2 of [LISP] 595 for more information on the use of the Map-Request ITR RLOC field. 596 Keep in mind that the ITR RLOC field supports mulitple RLOCs in 597 multiple address families, so a Map-Reply sent in response to a Map- 598 Request is not necessarily sent to back to the Map-Request RLOC 599 source. 601 There may be scenarios, perhaps to encourage caching of EID-to-RLOC 602 mappings by ALT Routers, where Map-Replies could be sent over the ALT 603 or where a "first-hop" ALT router might modify the originating RLOC 604 on a Map-Request received from an ITR to force the Map-Reply to be 605 returned to the "first-hop" ALT Router. These cases will not be 606 supported by initial LISP+ALT implementations but may be subject to 607 future experimentation. 609 ALT Routers propagate path information via BGP ([RFC4271]) that is 610 used by ITRs to send ALT Datagrams toward the appropriate ETR for 611 each EID-prefix. BGP is run on the inter-ALT Router links, and 612 possibly between an edge ("last hop") ALT Router and an ETR or 613 between an edge ("first hop") ALT Router and an ITR. The ALT BGP RIB 614 consists of aggregated EID-prefixes and their next hops toward the 615 authoritative ETR for that EID-prefix. 617 5.1. Changes to ITR behavior with LISP+ALT 619 As previously described, an ITR will usually use the Map Resolver 620 interface and will send its Map Requests to a Map Resolver. When an 621 ITR instead connects via tunnels and BGP to the ALT, it sends ALT 622 Datagrams to one of its "upstream" ALT Routers; these are sent only 623 to obtain new EID-to-RLOC mappings - RLOC probe and cache TTL refresh 624 Map-Requests are not sent on the ALT. As in basic LISP, it should 625 use one of its RLOCs as the source address of these queries; it 626 should not use a tunnel interface as the source address as doing so 627 will cause replies to be forwarded over the tunneled topology and may 628 be problematic if the tunnel interface address is not routed 629 throughout the ALT. If the ITR is running BGP with the LISP+ALT 630 router(s), it selects the appropriate ALT Router based on the BGP 631 information received. If it is not running BGP, it uses a 632 statically-configued ALT Default Route to select an ALT Router. 634 5.2. Changes to ETR behavior with LISP+ALT 636 As previously described, an ETR will usually use the Map Server 637 interface (see [LISP-MS]) and will register its EID-prefixes with its 638 configured Map Servers. When an ETR instead connects using BGP to 639 one or more ALT Routers, it announces its EID-prefix(es) to those ALT 640 Routers. 642 As documented in [LISP], when an ETR generates a Map-Reply message to 643 return to a querying ITR, it sets the outer header IP destination 644 address to one of the requesting ITR's RLOCs so that the Map-Reply 645 will be sent on the underlying Internet topology, not on the ALT; 646 this avoids any latency penalty (or "stretch") that might be incurred 647 by sending the Map-Reply via the ALT, reduces load on the ALT, and 648 ensures that the Map-Reply can be routed even if the original ITR 649 does not have an ALT-routed EID. For details on how an ETR selects 650 which ITR RLOC to use, see section 6.1.5 of [LISP]. 652 6. BGP configuration and protocol considerations 654 6.1. Autonomous System Numbers (ASNs) in LISP+ALT 656 The primary use of BGP today is to define the global Internet routing 657 topology in terms of its participants, known as Autonomous Systems. 658 LISP+ALT specifies the use of BGP to create a global overlay network 659 (the ALT) for finding EID-to-RLOC mappings. While related to the 660 global routing database, the ALT serves a very different purpose and 661 is organized into a very different hierarchy. Because LISP+ALT does 662 use BGP, however, it uses ASNs in the paths that are propagated among 663 ALT Routers. To avoid confusion, LISP+ALT should use newly-assigned 664 AS numbers that are unrelated to the ASNs used by the global routing 665 system. Exactly how this new space will be assigned and managed will 666 be determined during the deployment of LISP+ALT. 668 Note that the ALT Routers that make up the "core" of the ALT will not 669 be associated with any existing core-Internet ASN because the ALT 670 topology is completely separate from, and independent of, the global 671 Internet routing system. 673 6.2. Sub-Address Family Identifier (SAFI) for LISP+ALT 675 As defined by this document, LISP+ALT may be implemented using BGP 676 without modification. Given the fundamental operational difference 677 between propagating global Internet routing information (the current 678 dominant use of BGP) and creating an overlay network for finding EID- 679 to-RLOC mappings (the use of BGP proposed by this document), it may 680 be desirable to assign a new SAFI [RFC4760] to prevent operational 681 confusion and difficulties, including the inadvertent leaking of 682 information from one domain to the other. Use of a separate SAFI 683 would make it easier to debug many operational problems but would 684 come at a significant cost: unmodified, off-the-shelf routers which 685 do not understand the new SAFI could not be used to build any part of 686 the ALT network. At present, this document does not request the 687 assignment of a new SAFI; additional experimentation may suggest the 688 need for one in the future. 690 7. EID-prefix Aggregation 692 The ALT BGP peering topology should be arranged in a tree-like 693 fashion (with some meshiness), with redundancy to deal with node and 694 link failures. A basic assumption is that as long as the routers are 695 up and running, the underlying Internet will provide alternative 696 routes to maintain BGP connectivity among ALT Routers. 698 Note that, as mentioned in Section 4.2, the use of BGP by LISP+ALT 699 requires that information only be aggregated where all active more- 700 specific prefixes of a generated aggregate prefix are known. This is 701 no different than the way that BGP route aggregation works in the 702 existing global routing system: a service provider only generates an 703 aggregate route if it is configured to learn to all prefixes that 704 make up that aggregate. 706 7.1. Stability of the ALT 708 It is worth noting that LISP+ALT does not directly propagate EID-to- 709 RLOC mappings. What it does is provide a mechanism for an ITR to 710 commonicate with the ETR that holds the mapping for a particular EID- 711 prefix. This distinction is important when considering the stability 712 of BGP on the ALT network as compared to the global routing system. 713 It also has implications for how site-specific EID-prefix information 714 may be used by LISP but not propagated by LISP+ALT (see Section 7.2 715 below). 717 RLOC prefixes are not propagated through the ALT so their 718 reachability is not determined through use of LISP+ALT. Instead, 719 reachability of RLOCs is learned through the LISP ITR-ETR exchange. 720 This means that link failures or other service disruptions that may 721 cause the reachability of an RLOC to change are not known to the ALT. 722 Changes to the presence of an EID-prefix on the ALT occur much less 723 frequently: only at subscription time or in the event of a failure of 724 the ALT infrastructure itself. This means that "flapping" (frequent 725 BGP updates and withdrawals due to prefix state changes) is not 726 likely and mapping information cannot become "stale" due to slow 727 propagation through the ALT BGP mesh. 729 7.2. Traffic engineering using LISP 731 Since an ITR learns an EID-to-RLOC mapping directly from the ETR that 732 owns it, it is possible to perform site-to-site traffic engineering 733 by setting the preference and/or weight fields, and by including 734 more-specific EID-to-RLOC information in Map-Reply messages. 736 This is a powerful mechanism that can conceivably replace the 737 traditional practice of routing prefix deaggregation for traffic 738 engineering purposes. Rather than propagating more-specific 739 information into the global routing system for local- or regional- 740 optimization of traffic flows, such more-specific information can be 741 exchanged, through LISP (not LISP+ALT), on an as-needed basis between 742 only those ITRs/ETRs (and, thus, site pairs) that need it. Such an 743 exchange of "more-specifics" between sites facilitates traffic 744 engineering, by allowing richer and more fine-grained policies to be 745 applied without advertising additional prefixes into either the ALT 746 or the global routing system. 748 Note that these new traffic engineering capabilities are an attribute 749 of LISP and are not specific to LISP+ALT; discussion is included here 750 because the BGP-based global routing system has traditionally used 751 propagation of more-specific routes as a crude form of traffic 752 engineering. 754 7.3. Edge aggregation and dampening 756 Normal BGP best common practices apply to the ALT network. In 757 particular, first-hop ALT Routers will aggregate EID prefixes and 758 dampen changes to them in the face of excessive updates. Since EID- 759 prefix assignments are not expected to change as frequently as global 760 routing BGP prefix reachability, such dampening should be very rare, 761 and might be worthy of logging as an exceptional event. It is again 762 worth noting that the ALT carries only EID-prefixes, used to a 763 construct BGP path to each ETR (or Map-Server) that originates each 764 prefix; the ALT does not carry reachability about RLOCs. In 765 addition, EID-prefix information may be aggregated as the topology 766 and address assignment hierarchy allow. Since the topology is all 767 tunneled and can be modified as needed, reasonably good aggregation 768 should be possible. In addition, since most ETRs are expected to 769 connect to the ALT using the Map Server interface, Map Servers will 770 implement a natural "edge" for the ALT where dampening and 771 aggregation can be applied. For these reasons, the set of prefix 772 information on the ALT can be expected to be both better aggregated 773 and considerably less volatile than the actual EID-to-RLOC mappings. 775 7.4. EID assignment flexibility vs. ALT scaling 777 There are major open questions regarding how the ALT will be deployed 778 and what organization(s) will operate it. In a simple, non- 779 distributed world, centralized administration of EID prefix 780 assignment and ALT network design would facilitate a well- aggregated 781 ALT routing system. Business and other realities will likely result 782 in a more complex, distributed system involving multiple levels of 783 prefix delegation, multiple operators of parts of the ALT 784 infrastructure, and a combination of competition and cooperation 785 among the participants. In addition, re-use of existing IP address 786 assignments, both "PI" and "PA", to avoid renumbering when sites 787 transition to LISP will further complicate the processes of building 788 and operating the ALT. 790 A number of conflicting considerations need to be kept in mind when 791 designing and building the ALT. Among them are: 793 1. Target ALT routing state size and level of aggregation. As 794 described in Section 7.1, the ALT should not suffer from some of 795 the performance constraints or stability issues as the Internet 796 global routing system, so some reasonable level of deaggregation 797 and increased number of EID prefixes beyond what might be 798 considered ideal should be acceptable. That said, measures, such 799 as tunnel rehoming to preserve aggregation when sites move from 800 one mapping provider to another and implementing aggregation at 801 multiple levels in the hierarchy to collapse de-aggregation at 802 lower levels, should be taken to reduce unnecessary explosion of 803 ALT routing state. 805 2. Number of operators of parts of the ALT and how they will be 806 organized (hierarchical delegation vs. shared administration). 807 This will determine not only how EID prefixes are assigned but 808 also how tunnels are configured and how EID prefixes can be 809 aggregated between different parts of the ALT. 811 3. Number of connections between different parts of the ALT. Trade- 812 offs will need to be made among resilience, performance, and 813 placement of aggregation boundaries. 815 4. EID prefix portability between competing operators of the ALT 816 infrastructure. A significant benefit for an end-site to adopt 817 LISP is the availability of EID space that is not tied to a 818 specific connectivity provider; it is important to ensure that an 819 end site doesn't trade lock-in to a connectivity provider for 820 lock-in to a provider of its EID assignment, ALT connectivity, or 821 Map Server facilities. 823 This is, by no means, an exhaustive list. 825 While resolving these issues is beyond the scope of this document, 826 the authors recommend that existing distributed resource structures, 827 such as the IANA/Regional Internet Registries and the ICANN/Domain 828 Registrar, be carefully considered when designing and deploying the 829 ALT infrastructure. 831 8. Connecting sites to the ALT network 833 8.1. ETRs originating information into the ALT 835 EID-prefix information is originated into the ALT by three different 836 mechanisms: 838 Map Server: In most cases, a site will configure its ETR(s) to 839 register with one or more Map Servers (see [LISP-MS]), and does 840 not participate directly in the ALT. 842 BGP: For a site requiring complex control over their EID-prefix 843 origination into the ALT, an ETR may connect to the LISP+ALT 844 overlay network by running BGP to one or more ALT Router(s) over 845 tunnel(s). The ETR advertises reachability for its EID-prefixes 846 over these BGP connection(s). The edge ALT Router(s) that 847 receive(s) these prefixes then propagate(s) them into the ALT. 848 Here the ETR is simply an BGP peer of ALT Router(s) at the edge of 849 the ALT. Where possible, an ALT Router that receives EID-prefixes 850 from an ETR via BGP should aggregate that information. 852 Configuration: One or more ALT Router(s) may be configured to 853 originate an EID-prefix on behalf of the non-BGP-speaking ETR that 854 is authoritative for a prefix. As in the case above, the ETR is 855 connected to ALT Router(s) using GRE tunnel(s) but rather than BGP 856 being used, the ALT Router(s) are configured with what are in 857 effect "static routes" for the EID-prefixes "owned" by the ETR. 858 The GRE tunnel is used to route Map-Requests to the ETR. 860 Note: in all cases, an ETR may register to multiple Map Servers or 861 connect to multiple ALT Routers for the following reasons: 863 * redundancy, so that a particular ETR is still reachable even if 864 one path or tunnel is unavailable. 866 * to connect to different parts of the ALT hierarchy if the ETR 867 "owns" multiple EID-to-RLOC mappings for EID-prefixes that 868 cannot be aggregated by the same ALT Router (i.e. are not 869 topologically "close" to each other in the ALT). 871 8.2. ITRs Using the ALT 873 In the common configuration, an ITR does not need to know anything 874 about the ALT, since it sends Map-Requests to one of its configured 875 Map-Resolvers (see [LISP-MS]). There are two exceptional cases: 877 Static default: If a Map Resolver is not available but an ITR is 878 adjacent to an ALT Router (either over a common subnet or through 879 the use of a tunnel), it can use an ALT Default Route route to 880 cause all ALT Datagrams to be sent that ALT Router. This case is 881 expected to be rare. 883 Connection to ALT: A site with complex Internet connectivity needs 884 may need more fine-grained distinction between traffic to LISP- 885 capable and non-LISP-capable sites. Such a site may configure 886 each of its ITRs to connect directly to the ALT, using a tunnel 887 and BGP connection. In this case, the ITR will receive EID-prefix 888 routes from its BGP connection to the ALT Router and will LISP- 889 encapsulate and send ALT Datagrams through the tunnel to the ALT 890 Router. Traffic to other destinations may be forwarded (without 891 LISP encapsulation) to non-LISP next-hop routers that the ITR 892 knows. 894 In general, an ITR that connects to the ALT does so only to to ALT 895 Routers at the "edge" of the ALT (typically two for redundancy). 896 There may, though, be situations where an ITR would connect to 897 other ALT Routers to receive additional, shorter path information 898 about a portion of the ALT of interest to it. This can be 899 accomplished by establishing GRE tunnels between the ITR and the 900 set of ALT Routers with the additional information. This is a 901 purely local policy issue between the ITR and the ALT Routers in 902 question. 904 As described in [LISP-MS], Map-Resolvers do not accept or forward 905 Data Probes; in the rare scenario that an ITR does support and 906 originate Data Probes, it must do so using one of the exceptional 907 configurations described above. Note that the use of Data Probes is 908 discouraged at this time (see Section 3.3). 910 9. IANA Considerations 912 This document makes no request of the IANA. 914 10. Security Considerations 916 LISP+ALT shares many of the security characteristics of BGP. Its 917 security mechanisms are comprised of existing technologies in wide 918 operational use today, so securing the ALT should be mostly a matter 919 of applying the same technology that is used to secure the BGP-based 920 global routing system (see Section 10.3 below). 922 10.1. Apparent LISP+ALT Vulnerabilities 924 This section briefly lists the known potential vulnerabilities of 925 LISP+ALT. 927 Mapping Integrity: Can an attacker insert bogus mappings to black- 928 hole (create Denial-of-Service, or DoS attack) or intercept LISP 929 data-plane packets? 931 ALT Router Availability: Can an attacker DoS the ALT Routers 932 connected to a given ETR? If a site's ETR cannot advertise its 933 EID-to-RLOC mappings, the site is essentially unavailable. 935 ITR Mapping/Resources: Can an attacker force an ITR or ALT Router to 936 drop legitimate mapping requests by flooding it with random 937 destinations for which it will generate large numbers of Map- 938 Requests and fill its mapping cache? Further study is required to 939 see the impact of admission control on the overlay network. 941 EID Map-Request Exploits for Reconnaissance: Can an attacker learn 942 about a LISP site's TE policy by sending legitimate mapping 943 requests and then observing the RLOC mapping replies? Is this 944 information useful in attacking or subverting peer relationships? 945 Note that any public LISP mapping database will have similar data- 946 plane reconnaissance issue. 948 Scaling of ALT Router Resources: Paths through the ALT may be of 949 lesser bandwidth than more "direct" paths; this may make them more 950 prone to high-volume denial-of-service attacks. For this reason, 951 all components of the ALT (ETRs and ALT Routers) should be 952 prepared to rate-limit traffic (ALT Datagrams) that could be 953 received across the ALT. 955 UDP Map-Reply from ETR: Since Map-Replies are sent directly from the 956 ETR to the ITR's RLOC, the ITR's RLOC may be vulnerable to various 957 types of DoS attacks (this is a general property of LISP, not an 958 LISP+ALT vulnerability). 960 More-specific prefix leakage: Because EID-prefixes on the ALT are 961 expected to be fairly well-aggregated and EID-prefixes propagated 962 out to the global Internet (see [LISP-IW] much more so, accidental 963 leaking or malicious advertisement of an EID-prefix into the 964 global routing system could cause traffic redirection away from a 965 LISP site. This is not really a new problem, though, and its 966 solution can only be achieved by much more strict prefix filtering 967 and authentication on the global routing system. 969 10.2. Survey of LISP+ALT Security Mechanisms 971 Explicit peering: The devices themselves can both prioritize 972 incoming packets, as well as potentially do key checks in hardware 973 to protect the control plane. 975 Use of TCP to connect elements: This makes it difficult for third 976 parties to inject packets. 978 Use of HMAC Protected BGP/TCP Connections: HMAC is used to verify 979 message integrity and authenticity, making it nearly impossible 980 for third party devices to either insert or modify messages. 982 Message Sequence Numbers and Nonce Values in Messages: This allows 983 an ITR to verify that the Map-Reply from an ETR is in response to 984 a Map-Request originated by that ITR (this is a general property 985 of LISP; LISP+ALT does not change this behavior). 987 10.3. Use of new IETF standard BGP Security mechanisms 989 LISP+ALT's use of BGP allows the ALT to take advantage of BGP 990 security features designed for existing Internet BGP use. Should the 991 Internet community converge on the work currently being done in the 992 IETF SIDR working group or should either S-BGP [I-D.murphy-bgp-secr] 993 or soBGP [I-D.white-sobgparchitecture] be implemented and widely- 994 deployed, LISP+ALT can readily use these mechanisms to provide 995 authentication of EID-prefix origination and EID-to-RLOC mappings. 997 11. Acknowledgments 999 The authors would like to specially thank J. Noel Chiappa who was a 1000 key contributer to the design of the LISP-CONS mapping database (many 1001 ideas from which made their way into LISP+ALT) and who has continued 1002 to provide invaluable insight as the LISP effort has evolved. Others 1003 who have provided valuable contributions include John Zwiebel, Hannu 1004 Flinck, Amit Jain, John Scudder, and Scott Brim. 1006 12. References 1008 12.1. Normative References 1010 [LISP] Farinacci, D., Fuller, V., Meyer, D., and D. Lewis, 1011 "Locator/ID Separation Protocol (LISP)", 1012 draft-ietf-lisp-15.txt (work in progress), July 2011. 1014 [LISP-MS] Fuller, V. and D. Farinacci, "LISP Map Server", 1015 draft-ietf-lisp-ms-11.txt (work in progress), August 2011. 1017 [RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P. 1018 Traina, "Generic Routing Encapsulation (GRE)", RFC 2784, 1019 March 2000. 1021 [RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway 1022 Protocol 4 (BGP-4)", RFC 4271, January 2006. 1024 [RFC4632] Fuller, V. and T. Li, "Classless Inter-domain Routing 1025 (CIDR): The Internet Address Assignment and Aggregation 1026 Plan", BCP 122, RFC 4632, August 2006. 1028 [RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter, 1029 "Multiprotocol Extensions for BGP-4", RFC 4760, 1030 January 2007. 1032 12.2. Informative References 1034 [I-D.murphy-bgp-secr] 1035 Murphy, S., "BGP Security Analysis", 1036 draft-murphy-bgp-secr-04 (work in progress), 1037 November 2001. 1039 [I-D.white-sobgparchitecture] 1040 White, R., "Architecture and Deployment Considerations for 1041 Secure Origin BGP (soBGP)", 1042 draft-white-sobgparchitecture-00 (work in progress), 1043 May 2004. 1045 [LISP-IW] Lewis, D., Meyer, D., Farinacci, D., and V. Fuller, 1046 "Interworking LISP with IPv4 and ipv6", 1047 draft-ietf-lisp-interworking-02.txt (work in progress), 1048 March 2011. 1050 Authors' Addresses 1052 Vince Fuller 1053 Cisco 1054 Tasman Drive 1055 San Jose, CA 95134 1056 USA 1058 Email: vaf@cisco.com 1060 Dino Farinacci 1061 Cisco 1062 Tasman Drive 1063 San Jose, CA 95134 1064 USA 1066 Email: dino@cisco.com 1068 Dave Meyer 1069 Cisco 1070 Tasman Drive 1071 San Jose, CA 95134 1072 USA 1074 Email: dmm@cisco.com 1076 Darrel Lewis 1077 Cisco 1078 Tasman Drive 1079 San Jose, CA 95134 1080 USA 1082 Email: darlewis@cisco.com