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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 (June 30, 2011) is 4676 days in the past. Is this intentional? Checking references for intended status: Experimental ---------------------------------------------------------------------------- == Outdated reference: A later version (-24) exists of draft-ietf-lisp-14 == Outdated reference: A later version (-16) exists of draft-ietf-lisp-ms-09 == Outdated reference: A later version (-06) exists of draft-ietf-lisp-interworking-02 Summary: 0 errors (**), 0 flaws (~~), 5 warnings (==), 1 comment (--).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: January 1, 2012 D. Lewis 6 Cisco 7 June 30, 2011 9 LISP Alternative Topology (LISP+ALT) 10 draft-ietf-lisp-alt-07.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 January 1, 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 . . . . . . . . . . 16 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. Note, though, 136 that organizational and operational considerations suggest that ALT 137 Routers be both logically and physically separate from the "native" 138 Internet packet transport system; deploying this overlay on those 139 routers which are already participating in the global routing system 140 and actively forwarding Internet traffic is not recommended. 142 The remainder of this document is organized as follows: Section 2 143 provides the definitions of terms used in this document. Section 3 144 outlines the LISP ALT model, where EID prefixes are routed across an 145 overlay network. Section 4 provides a basic overview of the LISP 146 Alternate Topology architecture, and Section 5 describes how the ALT 147 uses BGP to propagate Endpoint Identifier reachability over the 148 overlay network and Section 6 describes other considerations for 149 using BGP on the ALT. Section 7 describes the construction of the 150 ALT aggregation hierarchy, and Section 8 discusses how LISP+ALT 151 elements are connected to form the overlay network. 153 2. Definition of Terms 155 This section provides high-level definitions of LISP concepts and 156 components involved with and affected by LISP+ALT. 158 Alternative Logical Topology (ALT): The virtual overlay network 159 made up of tunnels between LISP+ALT Routers. The Border Gateway 160 Protocol (BGP) runs between ALT Routers and is used to carry 161 reachability information for EID-prefixes. The ALT provides a way 162 to forward Map-Requests (and, if supported, Data Probes) toward 163 the ETR that "owns" an EID-prefix. As a tunneled overlay, its 164 performance is expected to be quite limited so use of it to 165 forward high-bandwidth flows of Data Probes is strongly 166 discouraged (see Section 3.3 for additional discussion). 168 Legacy Internet: The portion of the Internet which does not run 169 LISP and does not participate in LISP+ALT. 171 ALT Router: The devices which run on the ALT. The ALT is a static 172 network built using tunnels between ALT Routers. These routers 173 are deployed in a roughly-hierarchical mesh in which routers at 174 each level in the topology are responsible for aggregating EID- 175 prefixes learned from those logically "below" them and advertising 176 summary prefixes to those logically "above" them. Prefix learning 177 and propagation between ALT Routers is done using BGP. An ALT 178 Router at the lowest level, or "edge" of the ALT, learns EID- 179 prefixes from its "client" ETRs. See Section 3.1 for a 180 description of how EID-prefixes are learned at the "edge" of the 181 ALT. See also Section 6 for details on how BGP is configured 182 between the different network elements. When an ALT Router 183 receives an ALT Datagram, it looks up the destination EID in its 184 forwarding table (composed of EID prefix routes it learned from 185 neighboring ALT Routers) and forwards it to the logical next-hop 186 on the overlay network. 188 Endpoint ID (EID): A 32-bit (for IPv4) or 128-bit (for ipv6) value 189 used to identify the ultimate source or destination for a LISP- 190 encapsulated packet. See [LISP] for details. 192 EID-prefix: A set of EIDs delegated in a power-of-two block. EID- 193 prefixes are routed on the ALT (not on the global Internet) and 194 are expected to be assigned in a hierarchical manner such that 195 they can be aggregated by ALT Routers. Such a block is 196 characterized by a prefix and a length. Note that while the ALT 197 routing system considers an EID-prefix to be an opaque block of 198 EIDs, an end site may put site-local, topologically-relevant 199 structure (subnetting) into an EID-prefix for intra-site routing. 201 Aggregated EID-prefixes: A set of individual EID-prefixes that have 202 been aggregated in the [RFC4632] sense. 204 Map Server (MS): An edge ALT Router that provides a registration 205 function for non-ALT-connected ETRs, originates EID-prefixes into 206 the ALT on behalf of those ETRs, and forwards Map-Requests to 207 them. See [LISP-MS] for details. 209 Map Resolver (MR): An edge ALT Router that accepts an Encapsulated 210 Map-Request from a non-ALT-connected ITR, decapsulates it, and 211 forwards it on to the ALT toward the ETR which owns the requested 212 EID-prefix. See [LISP-MS] for details. 214 Ingress Tunnel Router (ITR): A router which sends LISP Map- 215 Requests or encapsulates IP datagrams with LISP headers, as 216 defined in [LISP]. In this document, the term refers to any 217 device implementing ITR functionality, including a Proxy-ITR (see 218 [LISP-IW]). Under some circumstances, a LISP Map Resolver may 219 also originate Map-Requests (see [LISP-MS]). 221 Egress Tunnel Router (ETR): A router which sends LISP Map-Replies 222 in response to LISP Map-Requests and decapsulates LISP- 223 encapsulated IP datagrams for delivery to end systems, as defined 224 in [LISP]. In this document, the term refers to any device 225 implementing ETR functionality, including a Proxy-ETR (see 226 [LISP-IW]). Under some circumstances, a LISP Map Server may also 227 respond to Map-Requests (see [LISP-MS]). 229 Routing Locator (RLOC): A routable IP address for a LISP tunnel 230 router (ITR or ETR). Interchangeably referred to as a "locator" 231 in this document. An RLOC is also the output of an EID-to-RLOC 232 mapping lookup; an EID-prefix maps to one or more RLOCs. 233 Typically, RLOCs are numbered from topologically-aggregatable 234 blocks that are assigned to a site at each point where it attaches 235 to the global Internet; where the topology is defined by the 236 connectivity of provider networks, RLOCs can be thought of as 237 Provider Aggregatable (PA) addresses. Routing for RLOCs is not 238 carried on the ALT. 240 EID-to-RLOC Mapping: A binding between an EID-prefix and the set of 241 RLOCs that can be used to reach it; sometimes referred to simply 242 as a "mapping". 244 EID-prefix Reachability: An EID-prefix is said to be "reachable" if 245 at least one of its locators is reachable. That is, an EID-prefix 246 is reachable if the ETR that is authoritative for a given EID-to- 247 RLOC mapping is reachable. 249 Default Mapping: A Default Mapping is a mapping entry for EID- 250 prefix 0.0.0.0/0 (0::/0 for ipv6). It maps to a locator-set used 251 for all EIDs in the Internet. If there is a more specific EID- 252 prefix in the mapping cache it overrides the Default Mapping 253 entry. The Default Mapping can be learned by configuration or 254 from a Map-Reply message. 256 ALT Default Route: An EID-prefix value of 0.0.0.0/0 (or 0::/0 for 257 ipv6) which may be learned from the ALT or statically configured 258 on an edge ALT Router. The ALT-Default Route defines a forwarding 259 path for a packet to be sent into the ALT on a router which does 260 not have a full ALT forwarding database. 262 3. The LISP+ALT model 264 The LISP+ALT model uses the same basic query/response protocol that 265 is documented in [LISP]. In particular, LISP+ALT provides two types 266 of packet that an ITR can originate to obtain EID-to-RLOC mappings: 268 Map-Request: A Map-Request message is sent into the ALT to request 269 an EID-to-RLOC mapping. The ETR which owns the mapping will 270 respond to the ITR with a Map-Reply message. Since the ALT only 271 forwards on EID destinations, the destination address of the Map- 272 Request sent on the ALT must be an EID. 274 Data Probe: Alternatively, an ITR may encapsulate and send the first 275 data packet destined for an EID with no known RLOCs into the ALT 276 as a Data Probe. This might be done minimize packet loss and to 277 probe for the mapping. As above, the authoritative ETR for the 278 EID-prefix will respond to the ITR with a Map-Reply message when 279 it receives the data packet over the ALT. As a side-effect, the 280 encapsulated data packet is delivered to the end-system at the ETR 281 site. Note that the Data Probe's inner IP destination address, 282 which is an EID, is copied to the outer IP destination address so 283 that the resulting packet can be routed over the ALT. See 284 Section 3.3 for caveats on the usability of Data Probes. 286 The term "ALT Datagram" is short-hand for a Map-Request or Data Probe 287 to be sent into or forwarded on the ALT. Note that such packets use 288 an RLOC as the outer header source IP address and an EID as the outer 289 header destination IP address. 291 Detailed descriptions of the LISP packet types referenced by this 292 document may be found in [LISP]. 294 3.1. Routeability of EIDs 296 A LISP EID has the same syntax as IP address and can be used, 297 unaltered, as the source or destination of an IP datagram. In 298 general, though, EIDs are not routable on the public Internet; LISP+ 299 ALT provides a separate, virtual network, known as the LISP 300 Alternative Logical Topology (ALT) on which a datagram using an EID 301 as an IP destination address may be transmitted. This network is 302 built as an overlay on the public Internet using tunnels to 303 interconnect ALT Routers. BGP runs over these tunnels to propagate 304 path information needed to forward ALT Datagrams. Importantly, while 305 the ETRs are the source(s) of the unaggregated EID-prefixes, LISP+ALT 306 uses existing BGP mechanisms to aggregate this information. 308 3.1.1. Mechanisms for an ETR to originate EID-prefixes 310 There are three ways that an ETR may originate its mappings into the 311 ALT: 313 1. By registration with a Map Server as documented in [LISP-MS]. 314 This is the common case and is expected to be used by the 315 majority of ETRs. 317 2. Using a "static route" on the ALT. Where no Map-Server is 318 available, an edge ALT Router may be configured with a "static 319 EID-prefix route" pointing to an ETR. 321 3. Edge connection to the ALT. If a site requires fine- grained 322 control over how its EID-prefixes are advertised into the ALT, it 323 may configure its ETR(s) with tunnel and BGP connections to edge 324 ALT Routers. 326 3.1.2. Mechanisms for an ITR to forward to EID-prefixes 328 There are three ways that an ITR may send ALT Datagrams: 330 1. Through a Map Resolver as documented in [LISP-MS]. This is the 331 common case and is expected to be used by the majority of ITRs. 333 2. Using a "default route". Where a Map Resolver is not available, 334 an ITR may be configured with a static ALT Default Route pointing 335 to an edge ALT Router. 337 3. Edge connection to the ALT. If a site requires fine-grained 338 knowledge of what prefixes exist on the ALT, it may configure its 339 ITR(s) with tunnel and BGP connections to edge ALT Routers. 341 3.1.3. Map Server Model preferred 343 The ALT-connected ITR and ETR cases are expected to be rare, as the 344 Map Server/Map Resolver model is both simpler for an ITR/ETR operator 345 to use, and provides a more general service interface to not only the 346 ALT, but also to other mapping databases that may be developed in the 347 future. 349 3.2. Connectivity to non-LISP sites 351 As stated above, EIDs used as IP addresses by LISP sites are not 352 routable on the public Internet. This implies that, absent a 353 mechanism for communication between LISP and non-LISP sites, 354 connectivity between them is not possible. To resolve this problem, 355 an "interworking" technology has been defined; see [LISP-IW] for 356 details. 358 3.3. Caveats on the use of Data Probes 360 It is worth noting that there has been a great deal of discussion and 361 controversy about whether Data Probes are a good idea. On the one 362 hand, using them offers a method of avoiding the "first packet drop" 363 problem when an ITR does not have a mapping for a particular EID- 364 prefix. On the other hand, forwarding data packets on the ALT would 365 require that it either be engineered to support relatively high 366 traffic rates, which is not generally feasible for a tunneled 367 network, or that it be carefully designed to aggressively rate-limit 368 traffic to avoid congestion or DoS attacks. There may also be issues 369 caused by different latency or other performance characteristics 370 between the ALT path taken by an initial Data Probe and the 371 "Internet" path taken by subsequent packets on the same flow once a 372 mapping is in place on an ITR. For these reasons, the use of Data 373 Probes is not recommended at this time; they should only be 374 originated an ITR when explicitly configured to do so and such 375 configuration should only be enabled when performing experiments 376 intended to test the viability of using Data Probes. 378 4. LISP+ALT: Overview 380 LISP+ALT is a hybrid push/pull architecture. Aggregated EID-prefixes 381 are advertised among the ALT Routers and to those (rare) ITRs that 382 are directly connected via a tunnel and BGP to the ALT. Specific 383 EID-to-RLOC mappings are requested by an ITR (and returned by an ETR) 384 using LISP when it sends a request either via a Map Resolver or to an 385 edge ALT Router. 387 The basic idea embodied in LISP+ALT is to use BGP, running on a 388 tunneled overlay network (the ALT), to establish reachability between 389 ALT Routers. The ALT BGP Route Information Base (RIB) is comprised 390 of EID-prefixes and associated next hops. ALT Routers interconnect 391 using BGP and propagate EID-prefix updates among themselves. EID- 392 prefix information is learned from ETRs at the "edge" of the ALT 393 either through the use of the Map Server interface (the commmon 394 case), static configuration, or by BGP-speaking ETRs. 396 An ITR uses the ALT to learn the best path for forwarding an ALT 397 Datagram destined to a particular EID-prefix. An ITR will normally 398 use a Map Resolver to send its ALT Datagrams on to the ALT but may, 399 in unusual circumstances, use a static ALT Default Route or connect 400 to the ALT using BGP. 402 Note that while this document specifies the use of Generic Routing 403 Encapsulation (GRE) as a tunneling mechanism, there is no reason that 404 parts of the ALT cannot be built using other tunneling technologies, 405 particularly in cases where GRE does not meet security, management, 406 or other operational requirements. References to "GRE tunnel" in 407 later sections of this document should therefore not be taken as 408 prohibiting or precluding the use of other tunneling mechanisms. 409 Note also that two ALT Routers that are directly adjacent (with no 410 layer-3 router hops between them) need not use a tunnel between them; 411 in this case, BGP may be configured across the interfaces that 412 connect to their common subnet and that subnet is then considered to 413 be part of the ALT topology. Use of techniques such as "eBGP 414 multihop" to connect ALT Routers that do not share a tunnel or common 415 subnet is not recommended as the non-ALT Routers in between the ALT 416 Routers in such a configuration may not have information necessary to 417 forward ALT Datagrams destined to EID-prefixes exchanged across that 418 BGP session. 420 In summary, LISP+ALT uses BGP to build paths through ALT Routers so 421 that an ALT Datagram sent into the ALT can be forwarded to the ETR 422 that holds the EID-to-RLOC mapping for that EID-prefix. This 423 reachability is carried as IPv4 or ipv6 NLRI without modification 424 (since an EID-prefix has the same syntax as IPv4 or ipv6 address 425 prefix). ALT Routers establish BGP sessions with one another, 426 forming the ALT. An ALT Router at the "edge" of the topology learns 427 EID-prefixes originated by authoritative ETRs. Learning may be 428 though the Map Server interface, by static configuration, or via BGP 429 with the ETRs. An ALT Router may also be configured to aggregate 430 EID-prefixes received from ETRs or from other LISP+ALT routers that 431 are topologically "downstream" from it. 433 4.1. ITR traffic handling 435 When an ITR receives a packet originated by an end system within its 436 site (i.e. a host for which the ITR is the exit path out of the site) 437 and the destination EID for that packet is not known in the ITR's 438 mapping cache, the ITR creates either a Map-Request for the 439 destination EID or the original packet encapsulated as a Data Probe 440 (see Section 3.3 for caveats on the usability of Data Probes). The 441 result, known as an ALT Datagram, is then sent to an ALT Router (see 442 also [LISP-MS] for non-ALT-connected ITRs, noting that Data Probes 443 cannot be sent to a Map-Resolver). This "first hop" ALT Router uses 444 EID-prefix routing information learned from other ALT Routers via BGP 445 to guide the packet to the ETR which "owns" the prefix. Upon receipt 446 by the ETR, normal LISP processing occurs: the ETR responds to the 447 ITR with a LISP Map-Reply that lists the RLOCs (and, thus, the ETRs 448 to use) for the EID-prefix. For Data Probes, the ETR also 449 decapsulates the packet and transmits it toward its destination. 451 Upon receipt of the Map-Reply, the ITR installs the RLOC information 452 for a given prefix into a local mapping database. With these mapping 453 entries stored, additional packets destined to the given EID-prefix 454 are routed directly to an RLOC without use of the ALT, until either 455 the entry's TTL has expired, or the ITR can otherwise find no 456 reachable ETR. Note that a current mapping may exist that contains 457 no reachable RLOCs; this is known as a Negative Cache Entry and it 458 indicates that packets destined to the EID-prefix are to be dropped. 460 Full details on Map-Request/Map-Reply processing may be found in 461 [LISP]. 463 Traffic routed on to the ALT consists solely of ALT Datagrams, i.e. 464 Map-Requests and Data Probes (if supported). Given the relatively 465 low performance expected of a tuneled topology, ALT Routers (and Map 466 Resolvers) should aggressively rate-limit the ingress of ALT 467 Datagrams from ITRs and, if possible, should be configured to not 468 accept packets that are not ALT Datagrams. 470 4.2. EID Assignment - Hierarchy and Topology 472 EID-prefixes are expected to be allocated to a LISP site by Internet 473 Registries. Where a site has multiple allocations which are aligned 474 on a power-of-2 block boundary, they should be aggregated into a 475 single EID-prefix for advertisement. The ALT network is built in a 476 roughly hierarchical, partial mesh which is intended to allow 477 aggregation where clearly-defined hierarchical boundaries exist. 478 Building such a structure should minimize the number of EID-prefixes 479 carried by LISP+ALT nodes near the top of the hierarchy. 481 Routes on the ALT do not need to respond to changes in policy, 482 subscription, or underlying physical connectivity, so the topology 483 can remain relatively static and aggregation can be sustained. 484 Because routing on the ALT uses BGP, the same rules apply for 485 generating aggregates; in particular, a ALT Router should only be 486 configured to generate an aggregate if it is configured with BGP 487 sessions to all of the originators of components (more-specific 488 prefixes) of that aggregate. Not all of the components of need to be 489 present for the aggregate to be originated (some may be holes in the 490 covering prefix and some may be down) but the aggregating router must 491 be configured to learn the state of all of the components. 493 Under what circumstances the ALT Router actually generates the 494 aggregate is a matter of local policy: in some cases, it will be 495 statically configured to do so at all times with a "static discard" 496 route. In other cases, it may be configured to only generate the 497 aggregate prefix if at least one of the components of the aggregate 498 is learned via BGP. 500 An ALT Router must not generate an aggregate that includes a non- 501 LISP-speaking hole unless it can be configured to return a Negative 502 Map-Reply with action="Natively-Forward" (see [LISP]) if it receives 503 an ALT Datagram that matches that hole. If it receives an ALT 504 Datagram that matches a LISP-speaking hole that is currently not 505 reachable, it should return a Negative Map-Reply with action="drop". 506 Negative Map-Replies should be returned with a short TTL, as 507 specified in [LISP-MS]. Note that an off-the-shelf, non-LISP- 508 speaking router configured as an aggregating ALT Router cannot send 509 Negative Map-Replies, so such a router must never originate an 510 aggregate that includes a non-LISP-speaking hole. 512 This implies that two ALT Routers that share an overlapping set of 513 prefixes must exchange those prefixes if either is to generate and 514 export a covering aggregate for those prefixes. It also implies that 515 an ETR which connects to the ALT using BGP must maintain BGP sessions 516 with all of the ALT Routers that are configured to originate an 517 aggregate which covers that prefix and that each of those ALT Routers 518 must be explicitly configured to know the set of EID-prefixes that 519 make up any aggregate that it originates. See also [LISP-MS] for an 520 example of other ways that prefix origin consistency and aggregation 521 can be maintained. 523 As an example, consider ETRs that are originating EID-prefixes for 524 10.1.0.0/24, 10.1.64.0/24, 10.1.128.0/24, and 10.1.192.0/24. An ALT 525 Router should only be configured to generate an aggregate for 526 10.1.0.0/16 if it has BGP sessions configured with all of these ETRs, 527 in other words, only if it has sufficient knowledge about the state 528 of those prefixes to summarize them. If the Router originating 529 10.1.0.0/16 receives an ALT Datagram destined for 10.1.77.88, a non- 530 LISP destination covered by the aggregate, it returns a Negative Map- 531 Reply with action "Natively-Forward". If it receives an ALT Datagram 532 destined for 10.1.128.199 but the configured LISP prefix 533 10.1.128.0/24 is unreachable, it returns a Negative Map-Reply with 534 action "drop". 536 Note: much is currently uncertain about the best way to build the ALT 537 network; as testing and prototype deployment proceeds, a guide to how 538 to best build the ALT network will be developed. 540 4.3. Use of GRE and BGP between LISP+ALT Routers 542 The ALT network is built using GRE tunnels between ALT Routers. BGP 543 sessions are configured over those tunnels, with each ALT Router 544 acting as a separate AS "hop" in a Path Vector for BGP. For the 545 purposes of LISP+ALT, the AS-path is used solely as a shortest-path 546 determination and loop-avoidance mechanism. Because all next-hops 547 are on tunnel interfaces, no IGP is required to resolve those next- 548 hops to exit interfaces. 550 LISP+ALT's use of GRE and BGP facilities deployment and operation of 551 LISP because no new protocols need to be defined, implemented, or 552 used on the overlay topology; existing BGP/GRE tools and operational 553 expertise are also re-used. Tunnel address assignment is also easy: 554 since the addresses on an ALT tunnel are only used by the pair of 555 routers connected to the tunnel, the only requirement of the IP 556 addresses used to establish that tunnel is that the attached routers 557 be reachable by each other; any addressing plan, including private 558 addressing, can therefore be used for ALT tunnels. 560 5. EID-prefix Propagation and Map-Request Forwarding 562 As described in Section 8.2, an ITR sends an ALT Datagram to a given 563 EID-to-RLOC mapping. The ALT provides the infrastructure that allows 564 these requests to reach the authoritative ETR. 566 Note that under normal circumstances Map-Replies are not sent over 567 the ALT; an ETR sends a Map-Reply to one of the ITR RLOCs learned 568 from the original Map-Request. There may be scenarios, perhaps to 569 encourage caching of EID-to-RLOC mappings by ALT Routers, where Map- 570 Replies could be sent over the ALT or where a "first-hop" ALT router 571 might modify the originating RLOC on a Map-Request received from an 572 ITR to force the Map-Reply to be returned to the "first-hop" ALT 573 Router. These cases will not be supported by initial LISP+ALT 574 implementations but may be subject to future experimentation. 576 ALT Routers propagate path information via BGP ([RFC4271]) that is 577 used by ITRs to send ALT Datagrams toward the appropriate ETR for 578 each EID-prefix. BGP is run on the inter-ALT Router links, and 579 possibly between an edge ("last hop") ALT Router and an ETR or 580 between an edge ("first hop") ALT Router and an ITR. The ALT BGP RIB 581 consists of aggregated EID-prefixes and their next hops toward the 582 authoritative ETR for that EID-prefix. 584 5.1. Changes to ITR behavior with LISP+ALT 586 As previously described, an ITR will usually use the Map Resolver 587 interface and will send its Map Requests to a Map Resolver. When an 588 ITR instead connects via tunnels and BGP to the ALT, it sends ALT 589 Datagrams to one of its "upstream" ALT Routers; these are sent only 590 to obtain new EID-to-RLOC mappings - RLOC probe and cache TTL refresh 591 Map-Requests are not sent on the ALT. As in basic LISP, it should 592 use one of its RLOCs as the source address of these queries; it 593 should not use a tunnel interface as the source address as doing so 594 will cause replies to be forwarded over the tunneled topology and may 595 be problematic if the tunnel interface address is not routed 596 throughout the ALT. If the ITR is running BGP with the LISP+ALT 597 router(s), it selects the appropriate ALT Router based on the BGP 598 information received. If it is not running BGP, it uses a 599 statically-configued ALT Default Route to select an ALT Router. 601 5.2. Changes to ETR behavior with LISP+ALT 603 As previously described, an ETR will usually use the Map Server 604 interface (see [LISP-MS]) and will register its EID-prefixes with its 605 configured Map Servers. When an ETR instead connects using BGP to 606 one or more ALT Routers, it announces its EID-prefix(es) to those ALT 607 Routers. 609 As documented in [LISP], when an ETR generates a Map-Reply message to 610 return to a querying ITR, it sets the outer header IP destination 611 address to one of the requesting ITR's RLOCs so that the Map-Reply 612 will be sent on the underlying Internet topology, not on the ALT; 613 this avoids any latency penalty (or "stretch") that might be incurred 614 by sending the Map-Reply via the ALT, reduces load on the ALT, and 615 ensures that the Map-Reply can be routed even if the original ITR 616 does not have an ALT-routed EID. For details on how an ETR selects 617 which ITR RLOC to use, see section 6.1.5 of [LISP]. 619 6. BGP configuration and protocol considerations 621 6.1. Autonomous System Numbers (ASNs) in LISP+ALT 623 The primary use of BGP today is to define the global Internet routing 624 topology in terms of its participants, known as Autonomous Systems. 625 LISP+ALT specifies the use of BGP to create a global overlay network 626 (the ALT) for finding EID-to-RLOC mappings. While related to the 627 global routing database, the ALT serves a very different purpose and 628 is organized into a very different hierarchy. Because LISP+ALT does 629 use BGP, however, it uses ASNs in the paths that are propagated among 630 ALT Routers. To avoid confusion, it needs to be stressed that that 631 these LISP+ALT ASNs use a new numbering space that is unrelated to 632 the ASNs used by the global routing system. Exactly how this new 633 space will be assigned and managed will be determined during the 634 deployment of LISP+ALT. 636 Note that the ALT Routers that make up the "core" of the ALT will not 637 be associated with any existing core-Internet ASN because the ALT 638 topology is completely separate from, and independent of, the global 639 Internet routing system. 641 6.2. Sub-Address Family Identifier (SAFI) for LISP+ALT 643 As defined by this document, LISP+ALT may be implemented using BGP 644 without modification. Given the fundamental operational difference 645 between propagating global Internet routing information (the current 646 dominant use of BGP) and creating an overlay network for finding EID- 647 to-RLOC mappings (the use of BGP proposed by this document), it may 648 be desirable to assign a new SAFI [RFC4760] to prevent operational 649 confusion and difficulties, including the inadvertent leaking of 650 information from one domain to the other. Use of a separate SAFI 651 would make it easier to debug many operational problems but would 652 come at a significant cost: unmodified, off-the-shelf routers which 653 do not understand the new SAFI could not be used to build any part of 654 the ALT network. At present, this document does not request the 655 assignment of a new SAFI; additional experimentation may suggest the 656 need for one in the future. 658 7. EID-prefix Aggregation 660 The ALT BGP peering topology should be arranged in a tree-like 661 fashion (with some meshiness), with redundancy to deal with node and 662 link failures. A basic assumption is that as long as the routers are 663 up and running, the underlying Internet will provide alternative 664 routes to maintain BGP connectivity among ALT Routers. 666 Note that, as mentioned in Section 4.2, the use of BGP by LISP+ALT 667 requires that information only be aggregated where all active more- 668 specific prefixes of a generated aggregate prefix are known. This is 669 no different than the way that BGP route aggregation works in the 670 existing global routing system: a service provider only generates an 671 aggregate route if it is configured to learn to all prefixes that 672 make up that aggregate. 674 7.1. Stability of the ALT 676 It is worth noting that LISP+ALT does not directly propagate EID-to- 677 RLOC mappings. What it does is provide a mechanism for an ITR to 678 commonicate with the ETR that holds the mapping for a particular EID- 679 prefix. This distinction is important when considering the stability 680 of BGP on the ALT network as compared to the global routing system. 681 It also has implications for how site-specific EID-prefix information 682 may be used by LISP but not propagated by LISP+ALT (see Section 7.2 683 below). 685 RLOC prefixes are not propagated through the ALT so their 686 reachability is not determined through use of LISP+ALT. Instead, 687 reachability of RLOCs is learned through the LISP ITR-ETR exchange. 688 This means that link failures or other service disruptions that may 689 cause the reachability of an RLOC to change are not known to the ALT. 690 Changes to the presence of an EID-prefix on the ALT occur much less 691 frequently: only at subscription time or in the event of a failure of 692 the ALT infrastructure itself. This means that "flapping" (frequent 693 BGP updates and withdrawals due to prefix state changes) is not 694 likely and mapping information cannot become "stale" due to slow 695 propagation through the ALT BGP mesh. 697 7.2. Traffic engineering using LISP 699 Since an ITR learns an EID-to-RLOC mapping directly from the ETR that 700 owns it, it is possible to perform site-to-site traffic engineering 701 by setting the preference and/or weight fields, and by including 702 more-specific EID-to-RLOC information in Map-Reply messages. 704 This is a powerful mechanism that can conceivably replace the 705 traditional practice of routing prefix deaggregation for traffic 706 engineering purposes. Rather than propagating more-specific 707 information into the global routing system for local- or regional- 708 optimization of traffic flows, such more-specific information can be 709 exchanged, through LISP (not LISP+ALT), on an as-needed basis between 710 only those ITRs/ETRs (and, thus, site pairs) that need it. Such an 711 exchange of "more-specifics" between sites facilitates traffic 712 engineering, by allowing richer and more fine-grained policies to be 713 applied without advertising additional prefixes into either the ALT 714 or the global routing system. 716 Note that these new traffic engineering capabilities are an attribute 717 of LISP and are not specific to LISP+ALT; discussion is included here 718 because the BGP-based global routing system has traditionally used 719 propagation of more-specific routes as a crude form of traffic 720 engineering. 722 7.3. Edge aggregation and dampening 724 Normal BGP best common practices apply to the ALT network. In 725 particular, first-hop ALT Routers will aggregate EID prefixes and 726 dampen changes to them in the face of excessive updates. Since EID- 727 prefix assignments are not expected to change as frequently as global 728 routing BGP prefix reachability, such dampening should be very rare, 729 and might be worthy of logging as an exceptional event. It is again 730 worth noting that the ALT carries only EID-prefixes, used to a 731 construct BGP path to each ETR (or Map-Server) that originates each 732 prefix; the ALT does not carry reachability about RLOCs. In 733 addition, EID-prefix information may be aggregated as the topology 734 and address assignment hierarchy allow. Since the topology is all 735 tunneled and can be modified as needed, reasonably good aggregation 736 should be possible. In addition, since most ETRs are expected to 737 connect to the ALT using the Map Server interface, Map Servers will 738 implement a natural "edge" for the ALT where dampening and 739 aggregation can be applied. For these reasons, the set of prefix 740 information on the ALT can be expected to be both better aggregated 741 and considerably less volatile than the actual EID-to-RLOC mappings. 743 7.4. EID assignment flexibility vs. ALT scaling 745 There are major open questions regarding how the ALT will be deployed 746 and what organization(s) will operate it. In a simple, non- 747 distributed world, centralized administration of EID prefix 748 assignment and ALT network design would facilitate a well- aggregated 749 ALT routing system. Business and other realities will likely result 750 in a more complex, distributed system involving multiple levels of 751 prefix delegation, multiple operators of parts of the ALT 752 infrastructure, and a combination of competition and cooperation 753 among the participants. In addition, re-use of existing IP address 754 assignments, both "PI" and "PA", to avoid renumbering when sites 755 transition to LISP will further complicate the processes of building 756 and operating the ALT. 758 A number of conflicting considerations need to be kept in mind when 759 designing and building the ALT. Among them are: 761 1. Target ALT routing state size and level of aggregation. As 762 described in Section 7.1, the ALT should not suffer from some of 763 the performance constraints or stability issues as the Internet 764 global routing system, so some reasonable level of deaggregation 765 and increased number of EID prefixes beyond what might be 766 considered ideal should be acceptable. That said, measures, such 767 as tunnel rehoming to preserve aggregation when sites move from 768 one mapping provider to another and implementing aggregation at 769 multiple levels in the hierarchy to collapse de-aggregation at 770 lower levels, should be taken to reduce unnecessary explosion of 771 ALT routing state. 773 2. Number of operators of parts of the ALT and how they will be 774 organized (hierarchical delegation vs. shared administration). 775 This will determine not only how EID prefixes are assigned but 776 also how tunnels are configured and how EID prefixes can be 777 aggregated between different parts of the ALT. 779 3. Number of connections between different parts of the ALT. Trade- 780 offs will need to be made among resilience, performance, and 781 placement of aggregation boundaries. 783 4. EID prefix portability between competing operators of the ALT 784 infrastructure. A significant benefit for an end-site to adopt 785 LISP is the availability of EID space that is not tied to a 786 specific connectivity provider; it is important to ensure that an 787 end site doesn't trade lock-in to a connectivity provider for 788 lock-in to a provider of its EID assignment, ALT connectivity, or 789 Map Server facilities. 791 This is, by no means, an exhaustive list. 793 While resolving these issues is beyond the scope of this document, 794 the authors recommend that existing distributed resource structures, 795 such as the IANA/Regional Internet Registries and the ICANN/Domain 796 Registrar, be carefully considered when designing and deploying the 797 ALT infrastructure. 799 8. Connecting sites to the ALT network 801 8.1. ETRs originating information into the ALT 803 EID-prefix information is originated into the ALT by three different 804 mechanisms: 806 Map Server: In most cases, a site will configure its ETR(s) to 807 register with one or more Map Servers (see [LISP-MS]), and does 808 not participate directly in the ALT. 810 BGP: For a site requiring complex control over their EID-prefix 811 origination into the ALT, an ETR may connect to the LISP+ALT 812 overlay network by running BGP to one or more ALT Router(s) over 813 tunnel(s). The ETR advertises reachability for its EID-prefixes 814 over these BGP connection(s). The edge ALT Router(s) that 815 receive(s) these prefixes then propagate(s) them into the ALT. 816 Here the ETR is simply an BGP peer of ALT Router(s) at the edge of 817 the ALT. Where possible, an ALT Router that receives EID-prefixes 818 from an ETR via BGP should aggregate that information. 820 Configuration: One or more ALT Router(s) may be configured to 821 originate an EID-prefix on behalf of the non-BGP-speaking ETR that 822 is authoritative for a prefix. As in the case above, the ETR is 823 connected to ALT Router(s) using GRE tunnel(s) but rather than BGP 824 being used, the ALT Router(s) are configured with what are in 825 effect "static routes" for the EID-prefixes "owned" by the ETR. 826 The GRE tunnel is used to route Map-Requests to the ETR. 828 Note: in all cases, an ETR may register to multiple Map Servers or 829 connect to multiple ALT Routers for the following reasons: 831 * redundancy, so that a particular ETR is still reachable even if 832 one path or tunnel is unavailable. 834 * to connect to different parts of the ALT hierarchy if the ETR 835 "owns" multiple EID-to-RLOC mappings for EID-prefixes that 836 cannot be aggregated by the same ALT Router (i.e. are not 837 topologically "close" to each other in the ALT). 839 8.2. ITRs Using the ALT 841 In the common configuration, an ITR does not need to know anything 842 about the ALT, since it sends Map-Requests to one of its configured 843 Map-Resolvers (see [LISP-MS]). There are two exceptional cases: 845 Static default: If a Map Resolver is not available but an ITR is 846 adjacent to an ALT Router (either over a common subnet or through 847 the use of a tunnel), it can use an ALT Default Route route to 848 cause all ALT Datagrams to be sent that ALT Router. This case is 849 expected to be rare. 851 Connection to ALT: A site with complex Internet connectivity needs 852 may need more fine-grained distinction between traffic to LISP- 853 capable and non-LISP-capable sites. Such a site may configure 854 each of its ITRs to connect directly to the ALT, using a tunnel 855 and BGP connection. In this case, the ITR will receive EID-prefix 856 routes from its BGP connection to the ALT Router and will LISP- 857 encapsulate and send ALT Datagrams through the tunnel to the ALT 858 Router. Traffic to other destinations may be forwarded (without 859 LISP encapsulation) to non-LISP next-hop routers that the ITR 860 knows. 862 In general, an ITR that connects to the ALT does so only to to ALT 863 Routers at the "edge" of the ALT (typically two for redundancy). 864 There may, though, be situations where an ITR would connect to 865 other ALT Routers to receive additional, shorter path information 866 about a portion of the ALT of interest to it. This can be 867 accomplished by establishing GRE tunnels between the ITR and the 868 set of ALT Routers with the additional information. This is a 869 purely local policy issue between the ITR and the ALT Routers in 870 question. 872 As described in [LISP-MS], Map-Resolvers do not accept or forward 873 Data Probes; in the rare scenario that an ITR does support and 874 originate Data Probes, it must do so using one of the exceptional 875 configurations described above. Note that the use of Data Probes is 876 discouraged at this time (see Section 3.3). 878 9. IANA Considerations 880 This document makes no request of the IANA. 882 10. Security Considerations 884 LISP+ALT shares many of the security characteristics of BGP. Its 885 security mechanisms are comprised of existing technologies in wide 886 operational use today, so securing the ALT should be mostly a matter 887 of applying the same technology that is used to secure the BGP-based 888 global routing system (see Section 10.3 below). 890 10.1. Apparent LISP+ALT Vulnerabilities 892 This section briefly lists the known potential vulnerabilities of 893 LISP+ALT. 895 Mapping Integrity: Can an attacker insert bogus mappings to black- 896 hole (create Denial-of-Service, or DoS attack) or intercept LISP 897 data-plane packets? 899 ALT Router Availability: Can an attacker DoS the ALT Routers 900 connected to a given ETR? If a site's ETR cannot advertise its 901 EID-to-RLOC mappings, the site is essentially unavailable. 903 ITR Mapping/Resources: Can an attacker force an ITR or ALT Router to 904 drop legitimate mapping requests by flooding it with random 905 destinations for which it will generate large numbers of Map- 906 Requests and fill its mapping cache? Further study is required to 907 see the impact of admission control on the overlay network. 909 EID Map-Request Exploits for Reconnaissance: Can an attacker learn 910 about a LISP site's TE policy by sending legitimate mapping 911 requests and then observing the RLOC mapping replies? Is this 912 information useful in attacking or subverting peer relationships? 913 Note that any public LISP mapping database will have similar data- 914 plane reconnaissance issue. 916 Scaling of ALT Router Resources: Paths through the ALT may be of 917 lesser bandwidth than more "direct" paths; this may make them more 918 prone to high-volume denial-of-service attacks. For this reason, 919 all components of the ALT (ETRs and ALT Routers) should be 920 prepared to rate-limit traffic (ALT Datagrams) that could be 921 received across the ALT. 923 UDP Map-Reply from ETR: Since Map-Replies are sent directly from the 924 ETR to the ITR's RLOC, the ITR's RLOC may be vulnerable to various 925 types of DoS attacks (this is a general property of LISP, not an 926 LISP+ALT vulnerability). 928 More-specific prefix leakage: Because EID-prefixes on the ALT are 929 expected to be fairly well-aggregated and EID-prefixes propagated 930 out to the global Internet (see [LISP-IW] much more so, accidental 931 leaking or malicious advertisement of an EID-prefix into the 932 global routing system could cause traffic redirection away from a 933 LISP site. This is not really a new problem, though, and its 934 solution can only be achieved by much more strict prefix filtering 935 and authentication on the global routing system. 937 10.2. Survey of LISP+ALT Security Mechanisms 939 Explicit peering: The devices themselves can both prioritize 940 incoming packets, as well as potentially do key checks in hardware 941 to protect the control plane. 943 Use of TCP to connect elements: This makes it difficult for third 944 parties to inject packets. 946 Use of HMAC Protected BGP/TCP Connections: HMAC is used to verify 947 message integrity and authenticity, making it nearly impossible 948 for third party devices to either insert or modify messages. 950 Message Sequence Numbers and Nonce Values in Messages: This allows 951 an ITR to verify that the Map-Reply from an ETR is in response to 952 a Map-Request originated by that ITR (this is a general property 953 of LISP; LISP+ALT does not change this behavior). 955 10.3. Use of new IETF standard BGP Security mechanisms 957 LISP+ALT's use of BGP allows the ALT to take advantage of BGP 958 security features designed for existing Internet BGP use. Should the 959 Internet community converge on the work currently being done in the 960 IETF SIDR working group or should either S-BGP [I-D.murphy-bgp-secr] 961 or soBGP [I-D.white-sobgparchitecture] be implemented and widely- 962 deployed, LISP+ALT can readily use these mechanisms to provide 963 authentication of EID-prefix origination and EID-to-RLOC mappings. 965 11. Acknowledgments 967 The authors would like to specially thank J. Noel Chiappa who was a 968 key contributer to the design of the LISP-CONS mapping database (many 969 ideas from which made their way into LISP+ALT) and who has continued 970 to provide invaluable insight as the LISP effort has evolved. Others 971 who have provided valuable contributions include John Zwiebel, Hannu 972 Flinck, Amit Jain, John Scudder, and Scott Brim. 974 12. References 976 12.1. Normative References 978 [LISP] Farinacci, D., Fuller, V., Meyer, D., and D. Lewis, 979 "Locator/ID Separation Protocol (LISP)", 980 draft-ietf-lisp-14.txt (work in progress), June 2011. 982 [LISP-MS] Fuller, V. and D. Farinacci, "LISP Map Server", 983 draft-ietf-lisp-ms-09.txt (work in progress), May 2011. 985 [RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P. 986 Traina, "Generic Routing Encapsulation (GRE)", RFC 2784, 987 March 2000. 989 [RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway 990 Protocol 4 (BGP-4)", RFC 4271, January 2006. 992 [RFC4632] Fuller, V. and T. Li, "Classless Inter-domain Routing 993 (CIDR): The Internet Address Assignment and Aggregation 994 Plan", BCP 122, RFC 4632, August 2006. 996 [RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter, 997 "Multiprotocol Extensions for BGP-4", RFC 4760, 998 January 2007. 1000 12.2. Informative References 1002 [I-D.murphy-bgp-secr] 1003 Murphy, S., "BGP Security Analysis", 1004 draft-murphy-bgp-secr-04 (work in progress), 1005 November 2001. 1007 [I-D.white-sobgparchitecture] 1008 White, R., "Architecture and Deployment Considerations for 1009 Secure Origin BGP (soBGP)", 1010 draft-white-sobgparchitecture-00 (work in progress), 1011 May 2004. 1013 [LISP-IW] Lewis, D., Meyer, D., Farinacci, D., and V. Fuller, 1014 "Interworking LISP with IPv4 and ipv6", 1015 draft-ietf-lisp-interworking-02.txt (work in progress), 1016 March 2011. 1018 Authors' Addresses 1020 Vince Fuller 1021 Cisco 1022 Tasman Drive 1023 San Jose, CA 95134 1024 USA 1026 Email: vaf@cisco.com 1028 Dino Farinacci 1029 Cisco 1030 Tasman Drive 1031 San Jose, CA 95134 1032 USA 1034 Email: dino@cisco.com 1036 Dave Meyer 1037 Cisco 1038 Tasman Drive 1039 San Jose, CA 95134 1040 USA 1042 Email: dmm@cisco.com 1044 Darrel Lewis 1045 Cisco 1046 Tasman Drive 1047 San Jose, CA 95134 1048 USA 1050 Email: darlewis@cisco.com