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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 (March 4, 2011) is 4796 days in the past. Is this intentional? Checking references for intended status: Experimental ---------------------------------------------------------------------------- == Outdated reference: A later version (-24) exists of draft-ietf-lisp-10 == Outdated reference: A later version (-16) exists of draft-ietf-lisp-ms-07 == Outdated reference: A later version (-06) exists of draft-ietf-lisp-interworking-02 Summary: 0 errors (**), 0 flaws (~~), 5 warnings (==), 1 comment (--).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: September 5, 2011 D. Lewis 6 Cisco 7 March 4, 2011 9 LISP Alternative Topology (LISP+ALT) 10 draft-ietf-lisp-alt-06.txt 12 Abstract 14 This document describes a simple mapping database to be used by the 15 Locator/ID Separation Protocol (LISP) to find Endpoint Identifier 16 (EID) to Routing Locator (RLOC) mappings. Termed the Alternative 17 Logical Topology (ALT), the database is built as an overlay network 18 on the public Internet using the Border Gateway Protocol (BGP) and 19 the Generic Routing Encapsulation (GRE). Using these proven 20 protocols, the ALT can be built and deployed relatively quickly 21 without major changes to the existing routing infrastructure. 23 Status of this Memo 25 This Internet-Draft is submitted in full conformance with the 26 provisions of BCP 78 and BCP 79. 28 Internet-Drafts are working documents of the Internet Engineering 29 Task Force (IETF). Note that other groups may also distribute 30 working documents as Internet-Drafts. The list of current Internet- 31 Drafts is at http://datatracker.ietf.org/drafts/current/. 33 Internet-Drafts are draft documents valid for a maximum of six months 34 and may be updated, replaced, or obsoleted by other documents at any 35 time. It is inappropriate to use Internet-Drafts as reference 36 material or to cite them other than as "work in progress." 38 This Internet-Draft will expire on September 5, 2011. 40 Copyright Notice 42 Copyright (c) 2011 IETF Trust and the persons identified as the 43 document authors. All rights reserved. 45 This document is subject to BCP 78 and the IETF Trust's Legal 46 Provisions Relating to IETF Documents 47 (http://trustee.ietf.org/license-info) in effect on the date of 48 publication of this document. Please review these documents 49 carefully, as they describe your rights and restrictions with respect 50 to this document. Code Components extracted from this document must 51 include Simplified BSD License text as described in Section 4.e of 52 the Trust Legal Provisions and are provided without warranty as 53 described in the Simplified BSD License. 55 Table of Contents 57 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 58 2. Definition of Terms . . . . . . . . . . . . . . . . . . . . . 5 59 3. The LISP+ALT model . . . . . . . . . . . . . . . . . . . . . . 8 60 3.1. Routeability of EIDs . . . . . . . . . . . . . . . . . . . 8 61 3.1.1. Mechanisms for an ETR to originate EID-prefixes . . . 9 62 3.1.2. Mechanisms for an ITR to forward to EID-prefixes . . . 9 63 3.1.3. Map Server Model preferred . . . . . . . . . . . . . . 9 64 3.2. Connectivity to non-LISP sites . . . . . . . . . . . . . . 9 65 3.3. Caveats on the use of Data Probes . . . . . . . . . . . . 10 66 4. LISP+ALT: Overview . . . . . . . . . . . . . . . . . . . . . . 11 67 4.1. ITR traffic handling . . . . . . . . . . . . . . . . . . . 12 68 4.2. EID Assignment - Hierarchy and Topology . . . . . . . . . 12 69 4.3. Use of GRE and BGP between LISP+ALT Routers . . . . . . . 14 70 5. EID-prefix Propagation and Map-Request Forwarding . . . . . . 15 71 5.1. Changes to ITR behavior with LISP+ALT . . . . . . . . . . 15 72 5.2. Changes to ETR behavior with LISP+ALT . . . . . . . . . . 15 73 6. BGP configuration and protocol considerations . . . . . . . . 17 74 6.1. Autonomous System Numbers (ASNs) in LISP+ALT . . . . . . . 17 75 6.2. Sub-Address Family Identifier (SAFI) for LISP+ALT . . . . 17 76 7. EID-prefix Aggregation . . . . . . . . . . . . . . . . . . . . 18 77 7.1. Stability of the ALT . . . . . . . . . . . . . . . . . . . 18 78 7.2. Traffic engineering using LISP . . . . . . . . . . . . . . 18 79 7.3. Edge aggregation and dampening . . . . . . . . . . . . . . 19 80 7.4. EID assignment flexibility vs. ALT scaling . . . . . . . . 19 81 8. Connecting sites to the ALT network . . . . . . . . . . . . . 21 82 8.1. ETRs originating information into the ALT . . . . . . . . 21 83 8.2. ITRs Using the ALT . . . . . . . . . . . . . . . . . . . . 21 84 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23 85 10. Security Considerations . . . . . . . . . . . . . . . . . . . 24 86 10.1. Apparent LISP+ALT Vulnerabilities . . . . . . . . . . . . 24 87 10.2. Survey of LISP+ALT Security Mechanisms . . . . . . . . . . 25 88 10.3. Use of new IETF standard BGP Security mechanisms . . . . . 25 89 11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 26 90 12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 27 91 12.1. Normative References . . . . . . . . . . . . . . . . . . . 27 92 12.2. Informative References . . . . . . . . . . . . . . . . . . 27 93 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 28 95 1. Introduction 97 This document describes the LISP+ALT mapping database, to be used by 98 LISP to find EID-to-RLOC mappings. The ALT network is built using 99 the Border Gateway Protocol (BGP, [RFC4271]), the BGP multi-protocol 100 extension [RFC4760], and the Generic Routing Encapsulation (GRE, 101 [RFC2784]) to construct an overlay network of devices (ALT Routers) 102 which operate on EID-prefixes and use EIDs as forwarding 103 destinations. 105 ALT Routers advertise hierarchically-delegated segments of the EID 106 namespace (i.e., prefixes) toward the rest of the ALT; they also 107 forward traffic destined for an EID covered by one of those prefixes 108 toward the network element that is authoritative for that EID and is 109 the origin of the BGP advertisement for that EID-prefix. An Ingress 110 Tunnel Router (ITR) uses this overlay to send a LISP Map-Request (see 111 [LISP]) to the Egress Tunnel Router (ETR) that holds the EID-to-RLOC 112 mapping for a matching EID-prefix. In most cases, an ITR does not 113 connect directly to the overlay network but instead sends Map- 114 Requests via a Map-Resolver (MR; see [LISP-MS]) which does. 115 Likewise, in most cases, an ETR does not connect directly to the 116 overlay network but instead registers its EID-prefixes with a Map- 117 Server that advertises those EID-prefixes on to the ALT and forwards 118 Map-Requests for them to the ETR. 120 It is important to note that the ALT does not distribute actual EID- 121 to-RLOC mappings. What it does provide is a forwarding path from an 122 ITR (or MR) which requires an EID-to-RLOC mapping to an ETR which 123 holds that mapping. The ITR/MR uses this path to send an ALT 124 Datagram (see Section 3) to an ETR which then responds with a Map- 125 Reply containing the needed mapping information. 127 One design goal for LISP+ALT is to use existing technology wherever 128 possible. To this end, the ALT is intended to be built using off- 129 the-shelf routers which already implement the required protocols (BGP 130 and GRE); little, if any, LISP-specific modifications should be 131 needed for such devices to be deployed on the ALT. Note, though, 132 that organizational and operational considerations suggest that ALT 133 Routers be both logically and physically separate from the "native" 134 Internet packet transport system; deploying this overlay on those 135 routers which are already participating in the global routing system 136 and actively forwarding Internet traffic is not recommended. 138 The remainder of this document is organized as follows: Section 2 139 provides the definitions of terms used in this document. Section 3 140 outlines the basic LISP 1.5 model. Section 4 provides a basic 141 overview of the LISP Alternate Topology architecture, and Section 5 142 describes how the ALT uses BGP to propagate Endpoint Identifier 143 reachability over the overlay network and Section 6 describes other 144 considerations for using BGP on the ALT. Section 7 describes the 145 construction of the ALT aggregation hierarchy, and Section 8 146 discusses how LISP+ALT elements are connected to form the overlay 147 network. 149 2. Definition of Terms 151 LISP+ALT operates on two name spaces and introduces a new network 152 element, the LISP+ALT Router (see below). This section provides 153 high-level definitions of the LISP+ALT name spaces, network elements, 154 and message types. 156 Alternative Logical Topology (ALT): The virtual overlay network 157 made up of tunnels between LISP+ALT Routers. The Border Gateway 158 Protocol (BGP) runs between ALT Routers and is used to carry 159 reachability information for EID-prefixes. The ALT provides a way 160 to forward Map-Requests (and, if supported, Data Probes) toward 161 the ETR that "owns" an EID-prefix. As a tunneled overlay, its 162 performance is expected to be quite limited so use of it to 163 forward high-bandwidth flows of Data Probes is strongly 164 discouraged (see Section 3.3 for additional discussion). 166 Legacy Internet: The portion of the Internet which does not run 167 LISP and does not participate in LISP+ALT. 169 ALT Router: The devices which run on the ALT. The ALT is a static 170 network built using tunnels between ALT Routers. These routers 171 are deployed in a roughly-hierarchical mesh in which routers at 172 each level in the topology are responsible for aggregating EID- 173 prefixes learned from those logically "below" them and advertising 174 summary prefixes to those logically "above" them. Prefix learning 175 and propagation between ALT Routers is done using BGP. An ALT 176 Router at the lowest level, or "edge" of the ALT, learns EID- 177 prefixes from its "client" ETRs. See Section 3.1 for a 178 description of how EID-prefixes are learned at the "edge" of the 179 ALT. See also Section 6 for details on how BGP is configured 180 between the different network elements. When an ALT Router 181 receives an ALT Datagram, it looks up the destination EID in its 182 forwarding table (composed of EID prefix routes it learned from 183 neighboring ALT Routers) and forwards it to the logical next-hop 184 on the overlay network. 186 Endpoint ID (EID): A 32-bit (for IPv4) or 128-bit (for ipv6) value 187 used to identify the ultimate source or destination for a LISP- 188 encapsulated packet. See [LISP] for details. 190 EID-prefix: A set of EIDs delegated in a power-of-two block. EID- 191 prefixes are routed on the ALT (not on the global Internet) and 192 are expected to be assigned in a hierarchical manner such that 193 they can be aggregated by ALT Routers. Such a block is 194 characterized by a prefix and a length. Note that while the ALT 195 routing system considers an EID-prefix to be an opaque block of 196 EIDs, an end site may put site-local, topologically-relevant 197 structure (subnetting) into an EID-prefix for intra-site routing. 199 Aggregated EID-prefixes: A set of individual EID-prefixes that have 200 been aggregated in the [RFC4632] sense. 202 Map Server (MS): An edge ALT Router that provides a registration 203 function for non-ALT-connected ETRs, originates EID-prefixes into 204 the ALT on behalf of those ETRs, and forwards Map-Requests to 205 them. See [LISP-MS] for details. 207 Map Resolver (MR): An edge ALT Router that accepts an Encapsulated 208 Map-Request from a non-ALT-connected ITR, decapsulates it, and 209 forwards it on to the ALT toward the ETR which owns the requested 210 EID-prefix. See [LISP-MS] for details. 212 Ingress Tunnel Router (ITR): A router which sends LISP Map- 213 Requests or encapsulates IP datagrams with LISP headers, as 214 defined in [LISP]. In this document, the term refers to any 215 device implementing ITR functionality, including a Proxy-ITR (see 216 [LISP-IW]). Under some circumstances, a LISP Map Resolver may 217 also originate Map-Requests (see [LISP-MS]). 219 Egress Tunnel Router (ETR): A router which sends LISP Map-Replies 220 in response to LISP Map-Requests and decapsulates LISP- 221 encapsulated IP datagrams for delivery to end systems, as defined 222 in [LISP]. In this document, the term refers to any device 223 implementing ETR functionality, including a Proxy-ETR (see 224 [LISP-IW]). Under some circumstances, a LISP Map Server may also 225 respond to Map-Requests (see [LISP-MS]). 227 Routing Locator (RLOC): A routable IP address for a LISP tunnel 228 router (ITR or ETR). Interchangeably referred to as a "locator" 229 in this document. An RLOC is also the output of an EID-to-RLOC 230 mapping lookup; an EID-prefix maps to one or more RLOCs. 231 Typically, RLOCs are numbered from topologically-aggregatable 232 blocks that are assigned to a site at each point where it attaches 233 to the global Internet; where the topology is defined by the 234 connectivity of provider networks, RLOCs can be thought of as 235 Provider Aggregatable (PA) addresses. Routing for RLOCs is not 236 carried on the ALT. 238 EID-to-RLOC Mapping: A binding between an EID-prefix and the set of 239 RLOCs that can be used to reach it; sometimes referred to simply 240 as a "mapping". 242 EID-prefix Reachability: An EID-prefix is said to be "reachable" if 243 at least one of its locators is reachable. That is, an EID-prefix 244 is reachable if the ETR that is authoritative for a given EID-to- 245 RLOC mapping is reachable. 247 Default Mapping: A Default Mapping is a mapping entry for EID- 248 prefix 0.0.0.0/0 (0::/0 for ipv6). It maps to a locator-set used 249 for all EIDs in the Internet. If there is a more specific EID- 250 prefix in the mapping cache it overrides the Default Mapping 251 entry. The Default Mapping can be learned by configuration or 252 from a Map-Reply message. 254 ALT Default Route: An EID-prefix value of 0.0.0.0/0 (or 0::/0 for 255 ipv6) which may be learned from the ALT or statically configured 256 on an edge ALT Router. The ALT-Default Route defines a forwarding 257 path for a packet to be sent into the ALT on a router which does 258 not have a full ALT forwarding database. 260 3. The LISP+ALT model 262 The LISP+ALT model uses the same basic query/response protocol that 263 is documented in [LISP]. In particular, LISP+ALT provides two types 264 of packet that an ITR can originate to obtain EID-to-RLOC mappings: 266 Map-Request: A Map-Request message is sent into the ALT to request 267 an EID-to-RLOC mapping. The ETR which owns the mapping will 268 respond to the ITR with a Map-Reply message. Since the ALT only 269 forwards on EID destinations, the destination address of the Map- 270 Request sent on the ALT must be an EID. See [LISP] for the format 271 of Map-Request and Map-Reply packets. 273 Data Probe: Alternatively, an ITR may encapsulate and send the first 274 data packet destined for an EID with no known RLOCs into the ALT 275 as a Data Probe. This might be done minimize packet loss and to 276 probe for the mapping. As above, the authoritative ETR for the 277 EID-prefix will respond to the ITR with a Map-Reply message when 278 it receives the data packet over the ALT. As a side-effect, the 279 encapsulated data packet is delivered to the end-system at the ETR 280 site. Note that the Data Probe's inner IP destination address, 281 which is an EID, is copied to the outer IP destination address so 282 that the resulting packet can be routed over the ALT. See 283 Section 3.3 for caveats on the usability of Data Probes. 285 The term "ALT Datagram" is short-hand for a Map-Request or Data Probe 286 to be sent into or forwarded on the ALT. Note that while the outer 287 header Source Address of an ALT Datagram is currently expected to be 288 an RLOC, there may be situations (e.g. for experimentation with 289 caching in intermediate ALT nodes) where an EID would be used to 290 force a Map-Reply to be routed back through the ALT. 292 3.1. Routeability of EIDs 294 A LISP EID has the same syntax as IP address and can be used, 295 unaltered, as the source or destination of an IP datagram. In 296 general, though, EIDs are not routable on the public Internet; LISP+ 297 ALT provides a separate, virtual network, known as the LISP 298 Alternative Logical Topology (ALT) on which a datagram using an EID 299 as an IP destination address may be transmitted. This network is 300 built as an overlay on the public Internet using tunnels to 301 interconnect ALT Routers. BGP runs over these tunnels to propagate 302 path information needed to forward ALT Datagrams. Importantly, while 303 the ETRs are the source(s) of the unaggregated EID-prefixes, LISP+ALT 304 uses existing BGP mechanisms to aggregate this information. 306 3.1.1. Mechanisms for an ETR to originate EID-prefixes 308 There are three ways that an ETR may originate its mappings into the 309 ALT: 311 1. By registration with a Map Server as documented in [LISP-MS]. 312 This is the common case and is expected to be used by the 313 majority of ETRs. 315 2. Using a "static route" on the ALT. Where no Map-Server is 316 available, an edge ALT Router may be configured with a "static 317 EID-prefix route" pointing to an ETR. 319 3. Edge connection to the ALT. If a site requires fine- grained 320 control over how its EID-prefixes are advertised into the ALT, it 321 may configure its ETR(s) with tunnel and BGP connections to edge 322 ALT Routers. 324 3.1.2. Mechanisms for an ITR to forward to EID-prefixes 326 There are three ways that an ITR may send ALT Datagrams: 328 1. Through a Map Resolver as documented in [LISP-MS]. This is the 329 common case and is expected to be used by the majority of ITRs. 331 2. Using a "default route". Where a Map Resolver is not available, 332 an ITR may be configured with a static ALT Default Route pointing 333 to an edge ALT Router. 335 3. Edge connection to the ALT. If a site requires fine-grained 336 knowledge of what prefixes exist on the ALT, it may configure its 337 ITR(s) with tunnel and BGP connections to edge ALT Routers. 339 3.1.3. Map Server Model preferred 341 The ALT-connected ITR and ETR cases are expected to be rare, as the 342 Map Server/Map Resolver model is both simpler for an ITR/ETR operator 343 to use, and provides a more general service interface to not only the 344 ALT, but also to other mapping databases that may be developed in the 345 future. 347 3.2. Connectivity to non-LISP sites 349 As stated above, EIDs used as IP addresses by LISP sites are not 350 routable on the public Internet. This implies that, absent a 351 mechanism for communication between LISP and non-LISP sites, 352 connectivity between them is not possible. To resolve this problem, 353 an "interworking" technology has been defined; see [LISP-IW] for 354 details. 356 3.3. Caveats on the use of Data Probes 358 It is worth noting that there has been a great deal of discussion and 359 controversy about whether Data Probes are a good idea. On the one 360 hand, using them offers a method of avoiding the "first packet drop" 361 problem when an ITR does not have a mapping for a particular EID- 362 prefix. On the other hand, forwarding data packets on the ALT would 363 require that it either be engineered to support relatively high 364 traffic rates, which is not generally feasible for a tunneled 365 network, or that it be carefully designed to aggressively rate-limit 366 traffic to avoid congestion or DoS attacks. There may also be issues 367 caused by different latency or other performance characteristics 368 between the ALT path taken by an initial Data Probe and the 369 "Internet" path taken by subsequent packets on the same flow once a 370 mapping is in place on an ITR. For these reasons, the use of Data 371 Probes is not recommended at this time; they should only be 372 originated an ITR when explicitly configured to do so and such 373 configuration should only be enabled when performing experiments 374 intended to test the viability of using Data Probes. 376 4. LISP+ALT: Overview 378 LISP+ALT is a hybrid push/pull architecture. Aggregated EID-prefixes 379 are advertised among the ALT Routers and to those (rare) ITRs that 380 are directly connected via a tunnel and BGP to the ALT. Specific 381 EID-to-RLOC mappings are requested by an ITR (and returned by an ETR) 382 using LISP when it sends a request either via a Map Resolver or to an 383 edge ALT Router. 385 The basic idea embodied in LISP+ALT is to use BGP, running on a 386 tunneled overlay network (the ALT), to establish reachability between 387 ALT Routers. The ALT BGP Route Information Base (RIB) is comprised 388 of EID-prefixes and associated next hops. ALT Routers interconnect 389 using BGP and propagate EID-prefix updates among themselves. EID- 390 prefix information is learned from ETRs at the "edge" of the ALT 391 either through the use of the Map Server interface (the commmon 392 case), static configuration, or by BGP-speaking ETRs. 394 An ITR uses the ALT to learn the best path for forwarding an ALT 395 Datagram destined to a particular EID-prefix. An ITR will normally 396 use a Map Resolver to send its ALT Datagrams on to the ALT but may, 397 in unusual circumstances, use a static ALT Default Route or connect 398 to the ALT using BGP. 400 Note that while this document specifies the use of Generic Routing 401 Encapsulation (GRE) as a tunneling mechanism, there is no reason that 402 parts of the ALT cannot be built using other tunneling technologies, 403 particularly in cases where GRE does not meet security, management, 404 or other operational requirements. References to "GRE tunnel" in 405 later sections of this document should therefore not be taken as 406 prohibiting or precluding the use of other tunneling mechanisms. 407 Note also that two ALT Routers that are directly adjacent (with no 408 layer-3 router hops between them) need not use a tunnel between them; 409 in this case, BGP may be configured across the interfaces that 410 connect to their common subnet and that subnet is then considered to 411 be part of the ALT topology. Use of techniques such as "eBGP 412 multihop" to connect ALT Routers that do not share a tunnel or common 413 subnet is not recommended as the non-ALT Routers in between the ALT 414 Routers in such a configuration may not have information necessary to 415 forward ALT Datagrams destined to EID-prefixes exchanged across that 416 BGP session. 418 In summary, LISP+ALT uses BGP to build paths through ALT Routers so 419 that an ALT Datagram sent into the ALT can be forwarded to the ETR 420 that holds the EID-to-RLOC mapping for that EID-prefix. This 421 reachability is carried as IPv4 or ipv6 NLRI without modification 422 (since an EID-prefix has the same syntax as IPv4 or ipv6 address 423 prefix). ALT Routers establish BGP sessions with one another, 424 forming the ALT. An ALT Router at the "edge" of the topology learns 425 EID-prefixes originated by authoritative ETRs. Learning may be 426 though the Map Server interface, by static configuration, or via BGP 427 with the ETRs. An ALT Router may also be configured to aggregate 428 EID-prefixes received from ETRs or from other LISP+ALT routers that 429 are topologically "downstream" from it. 431 4.1. ITR traffic handling 433 When an ITR receives a packet originated by an end system within its 434 site (i.e. a host for which the ITR is the exit path out of the site) 435 and the destination EID for that packet is not known in the ITR's 436 mapping cache, the ITR creates either a Map-Request for the 437 destination EID or the original packet encapsulated as a Data Probe 438 (see Section 3.3 for caveats on the usability of Data Probes). The 439 result, known as an ALT Datagram, is then sent to an ALT Router (see 440 also [LISP-MS] for non-ALT-connected ITRs, noting that Data Probes 441 cannot be sent to a Map-Resolver). This "first hop" ALT Router uses 442 EID-prefix routing information learned from other ALT Routers via BGP 443 to guide the packet to the ETR which "owns" the prefix. Upon receipt 444 by the ETR, normal LISP processing occurs: the ETR responds to the 445 ITR with a LISP Map-Reply that lists the RLOCs (and, thus, the ETRs 446 to use) for the EID-prefix. For Data Probes, the ETR also 447 decapsulates the packet and transmits it toward its destination. 449 Upon receipt of the Map-Reply, the ITR installs the RLOC information 450 for a given prefix into a local mapping database. With these mapping 451 entries stored, additional packets destined to the given EID-prefix 452 are routed directly to an RLOC without use of the ALT, until either 453 the entry's TTL has expired, or the ITR can otherwise find no 454 reachable ETR. Note that a current mapping may exist that contains 455 no reachable RLOCs; this is known as a Negative Cache Entry and it 456 indicates that packets destined to the EID-prefix are to be dropped. 458 Full details on Map-Request/Map-Reply processing may be found in 459 [LISP]. 461 Traffic routed on to the ALT consists solely of ALT Datagrams, i.e. 462 Map-Requests and Data Probes (if supported). Given the relatively 463 low performance expected of a tuneled topology, ALT Routers (and Map 464 Resolvers) should aggressively rate-limit the ingress of ALT 465 Datagrams from ITRs and, if possible, should be configured to not 466 accept packets that are not ALT Datagrams. 468 4.2. EID Assignment - Hierarchy and Topology 470 EID-prefixes are expected to be allocated to a LISP site by Internet 471 Registries. Where a site has multiple allocations which are aligned 472 on a power-of-2 block boundary, they should be aggregated into a 473 single EID-prefix for advertisement. The ALT network is built in a 474 roughly hierarchical, partial mesh which is intended to allow 475 aggregation where clearly-defined hierarchical boundaries exist. 476 Building such a structure should minimize the number of EID-prefixes 477 carried by LISP+ALT nodes near the top of the hierarchy. 479 Routes on the ALT do not need to respond to changes in policy, 480 subscription, or underlying physical connectivity, so the topology 481 can remain relatively static and aggregation can be sustained. 482 Because routing on the ALT uses BGP, the same rules apply for 483 generating aggregates; in particular, a ALT Router should only be 484 configured to generate an aggregate if it is configured with BGP 485 sessions to all of the originators of components (more-specific 486 prefixes) of that aggregate. Not all of the components of need to be 487 present for the aggregate to be originated (some may be holes in the 488 covering prefix and some may be down) but the aggregating router must 489 be configured to learn the state of all of the components. 491 Under what circumstances the ALT Router actually generates the 492 aggregate is a matter of local policy: in some cases, it will be 493 statically configured to do so at all times with a "static discard" 494 route. In other cases, it may be configured to only generate the 495 aggregate prefix if at least one of the components of the aggregate 496 is learned via BGP. 498 An ALT Router must not generate an aggregate that includes a non- 499 LISP-speaking hole unless it can be configured to return a Negative 500 Map-Reply with action="Natively-Forward" (see [LISP]) if it receives 501 an ALT Datagram that matches that hole. If it receives an ALT 502 Datagram that matches a LISP-speaking hole that is currently not 503 reachable, it should return a Negative Map-Reply with action="drop". 504 Negative Map-Replies should be returned with a short TTL, as 505 specified in [LISP-MS]. Note that an off-the-shelf, non-LISP- 506 speaking router configured as an aggregating ALT Router cannot send 507 Negative Map-Replies, so such a router must never originate an 508 aggregate that includes a non-LISP-speaking hole. 510 This implies that two ALT Routers that share an overlapping set of 511 prefixes must exchange those prefixes if either is to generate and 512 export a covering aggregate for those prefixes. It also implies that 513 an ETR which connects to the ALT using BGP must maintain BGP sessions 514 with all of the ALT Routers that are configured to originate an 515 aggregate which covers that prefix and that each of those ALT Routers 516 must be explicitly configured to know the set of EID-prefixes that 517 make up any aggregate that it originates. See also [LISP-MS] for an 518 example of other ways that prefix origin consistency and aggregation 519 can be maintained. 521 As an example, consider ETRs that are originating EID-prefixes for 522 10.1.0.0/24, 10.1.64.0/24, 10.1.128.0/24, and 10.1.192.0/24. An ALT 523 Router should only be configured to generate an aggregate for 524 10.1.0.0/16 if it has BGP sessions configured with all of these ETRs, 525 in other words, only if it has sufficient knowledge about the state 526 of those prefixes to summarize them. If the Router originating 527 10.1.0.0/16 receives an ALT Datagram destined for 10.1.77.88, a non- 528 LISP destination covered by the aggregate, it returns a Negative Map- 529 Reply with action "Natively-Forward". If it receives an ALT Datagram 530 destined for 10.1.128.199 but the configured LISP prefix 531 10.1.128.0/24 is unreachable, it returns a Negative Map-Reply with 532 action "drop". 534 Note: much is currently uncertain about the best way to build the ALT 535 network; as testing and prototype deployment proceeds, a guide to how 536 to best build the ALT network will be developed. 538 4.3. Use of GRE and BGP between LISP+ALT Routers 540 The ALT network is built using GRE tunnels between ALT Routers. BGP 541 sessions are configured over those tunnels, with each ALT Router 542 acting as a separate AS "hop" in a Path Vector for BGP. For the 543 purposes of LISP+ALT, the AS-path is used solely as a shortest-path 544 determination and loop-avoidance mechanism. Because all next-hops 545 are on tunnel interfaces, no IGP is required to resolve those next- 546 hops to exit interfaces. 548 LISP+ALT's use of GRE and BGP facilities deployment and operation of 549 LISP because no new protocols need to be defined, implemented, or 550 used on the overlay topology; existing BGP/GRE tools and operational 551 expertise are also re-used. Tunnel address assignment is also easy: 552 since the addresses on an ALT tunnel are only used by the pair of 553 routers connected to the tunnel, the only requirement of the IP 554 addresses used to establish that tunnel is that the attached routers 555 be reachable by each other; any addressing plan, including private 556 addressing, can therefore be used for ALT tunnels. 558 5. EID-prefix Propagation and Map-Request Forwarding 560 As described in Section 8.2, an ITR sends an ALT Datagram to a given 561 EID-to-RLOC mapping. The ALT provides the infrastructure that allows 562 these requests to reach the authoritative ETR. 564 Note that under normal circumstances Map-Replies are not sent over 565 the ALT; an ETR sends a Map-Reply to one of the ITR RLOCs learned 566 from the original Map-Request. There may be scenarios, perhaps to 567 encourage caching of EID-to-RLOC mappings by ALT Routers, where Map- 568 Replies could be sent over the ALT or where a "first-hop" ALT router 569 might modify the originating RLOC on a Map-Request received from an 570 ITR to force the Map-Reply to be returned to the "first-hop" ALT 571 Router. These cases will not be supported by initial LISP+ALT 572 implementations but may be subject to future experimentation. 574 ALT Routers propagate path information via BGP ([RFC4271]) that is 575 used by ITRs to send ALT Datagrams toward the appropriate ETR for 576 each EID-prefix. BGP is run on the inter-ALT Router links, and 577 possibly between an edge ("last hop") ALT Router and an ETR or 578 between an edge ("first hop") ALT Router and an ITR. The ALT BGP RIB 579 consists of aggregated EID-prefixes and their next hops toward the 580 authoritative ETR for that EID-prefix. 582 5.1. Changes to ITR behavior with LISP+ALT 584 As previously described, an ITR will usually use the Map Resolver 585 interface and will send its Map Requests to a Map Resolver. When an 586 ITR instead connects via tunnels and BGP to the ALT, it sends ALT 587 Datagrams to one of its "upstream" ALT Routers; these are sent only 588 to obtain new EID-to-RLOC mappings - RLOC probe and cache TTL refresh 589 Map-Requests are not sent on the ALT. As in basic LISP, it should 590 use one of its RLOCs as the source address of these queries; it 591 should not use a tunnel interface as the source address as doing so 592 will cause replies to be forwarded over the tunneled topology and may 593 be problematic if the tunnel interface address is not routed 594 throughout the ALT. If the ITR is running BGP with the LISP+ALT 595 router(s), it selects the appropriate ALT Router based on the BGP 596 information received. If it is not running BGP, it uses a 597 statically-configued ALT Default Route to select an ALT Router. 599 5.2. Changes to ETR behavior with LISP+ALT 601 As previously described, an ETR will usually use the Map Server 602 interface (see [LISP-MS]) and will register its EID-prefixes with its 603 configured Map Servers. When an ETR instead connects using BGP to 604 one or more ALT Routers, it announces its EID-prefix(es) to those ALT 605 Routers. 607 As documented in [LISP], when an ETR generates a Map-Reply message to 608 return to a querying ITR, it sets the outer header IP destination 609 address to one of the requesting ITR's RLOCs so that the Map-Reply 610 will be sent on the underlying Internet topology, not on the ALT; 611 this avoids any latency penalty (or "stretch") that might be incurred 612 by sending the Map-Reply via the ALT, reduces load on the ALT, and 613 ensures that the Map-Reply can be routed even if the original ITR 614 does not have an ALT-routed EID. For details on how an ETR selects 615 which ITR RLOC to use, see section 6.1.5 of [LISP]. 617 6. BGP configuration and protocol considerations 619 6.1. Autonomous System Numbers (ASNs) in LISP+ALT 621 The primary use of BGP today is to define the global Internet routing 622 topology in terms of its participants, known as Autonomous Systems. 623 LISP+ALT specifies the use of BGP to create a global overlay network 624 (the ALT) for finding EID-to-RLOC mappings. While related to the 625 global routing database, the ALT serves a very different purpose and 626 is organized into a very different hierarchy. Because LISP+ALT does 627 use BGP, however, it uses ASNs in the paths that are propagated among 628 ALT Routers. To avoid confusion, it needs to be stressed that that 629 these LISP+ALT ASNs use a new numbering space that is unrelated to 630 the ASNs used by the global routing system. Exactly how this new 631 space will be assigned and managed will be determined during the 632 deployment of LISP+ALT. 634 Note that the ALT Routers that make up the "core" of the ALT will not 635 be associated with any existing core-Internet ASN because the ALT 636 topology is completely separate from, and independent of, the global 637 Internet routing system. 639 6.2. Sub-Address Family Identifier (SAFI) for LISP+ALT 641 As defined by this document, LISP+ALT may be implemented using BGP 642 without modification. Given the fundamental operational difference 643 between propagating global Internet routing information (the current 644 dominant use of BGP) and creating an overlay network for finding EID- 645 to-RLOC mappings (the use of BGP proposed by this document), it may 646 be desirable to assign a new SAFI [RFC4760] to prevent operational 647 confusion and difficulties, including the inadvertent leaking of 648 information from one domain to the other. Use of a separate SAFI 649 would make it easier to debug many operational problems but would 650 come at a significant cost: unmodified, off-the-shelf routers which 651 do not understand the new SAFI could not be used to build any part of 652 the ALT network. At present, this document does not request the 653 assignment of a new SAFI; additional experimentation may suggest the 654 need for one in the future. 656 7. EID-prefix Aggregation 658 The ALT BGP peering topology should be arranged in a tree-like 659 fashion (with some meshiness), with redundancy to deal with node and 660 link failures. A basic assumption is that as long as the routers are 661 up and running, the underlying Internet will provide alternative 662 routes to maintain BGP connectivity among ALT Routers. 664 Note that, as mentioned in Section 4.2, the use of BGP by LISP+ALT 665 requires that information only be aggregated where all active more- 666 specific prefixes of a generated aggregate prefix are known. This is 667 no different than the way that BGP route aggregation works in the 668 existing global routing system: a service provider only generates an 669 aggregate route if it is configured to learn to all prefixes that 670 make up that aggregate. 672 7.1. Stability of the ALT 674 It is worth noting that LISP+ALT does not directly propagate EID-to- 675 RLOC mappings. What it does is provide a mechanism for an ITR to 676 commonicate with the ETR that holds the mapping for a particular EID- 677 prefix. This distinction is important when considering the stability 678 of BGP on the ALT network as compared to the global routing system. 679 It also has implications for how site-specific EID-prefix information 680 may be used by LISP but not propagated by LISP+ALT (see Section 7.2 681 below). 683 RLOC prefixes are not propagated through the ALT so their 684 reachability is not determined through use of LISP+ALT. Instead, 685 reachability of RLOCs is learned through the LISP ITR-ETR exchange. 686 This means that link failures or other service disruptions that may 687 cause the reachability of an RLOC to change are not known to the ALT. 688 Changes to the presence of an EID-prefix on the ALT occur much less 689 frequently: only at subscription time or in the event of a failure of 690 the ALT infrastructure itself. This means that "flapping" (frequent 691 BGP updates and withdrawals due to prefix state changes) is not 692 likely and mapping information cannot become "stale" due to slow 693 propagation through the ALT BGP mesh. 695 7.2. Traffic engineering using LISP 697 Since an ITR learns an EID-to-RLOC mapping directly from the ETR that 698 owns it, it is possible to perform site-to-site traffic engineering 699 by setting the preference and/or weight fields, and by including 700 more-specific EID-to-RLOC information in Map-Reply messages. 702 This is a powerful mechanism that can conceivably replace the 703 traditional practice of routing prefix deaggregation for traffic 704 engineering purposes. Rather than propagating more-specific 705 information into the global routing system for local- or regional- 706 optimization of traffic flows, such more-specific information can be 707 exchanged, through LISP (not LISP+ALT), on an as-needed basis between 708 only those ITRs/ETRs (and, thus, site pairs) that need it. Should a 709 receiving ITR decide that it does not wish to store such more- 710 specific information, it has the option of discarding it as long as a 711 shorter, covering EID-prefix exists. Such an exchange of "more- 712 specifics" between sites facilitates traffic engineering, by allowing 713 richer and more fine-grained policies to be applied without 714 advertising additional prefixes into either the ALT or the global 715 routing system. 717 Note that these new traffic engineering capabilities are an attribute 718 of LISP and are not specific to LISP+ALT; discussion is included here 719 because the BGP-based global routing system has traditionally used 720 propagation of more-specific routes as a crude form of traffic 721 engineering. 723 7.3. Edge aggregation and dampening 725 Normal BGP best common practices apply to the ALT network. In 726 particular, first-hop ALT Routers will aggregate EID prefixes and 727 dampen changes to them in the face of excessive updates. Since EID- 728 prefix assignments are not expected to change as frequently as global 729 routing BGP prefix reachability, such dampening should be very rare, 730 and might be worthy of logging as an exceptional event. It is again 731 worth noting that the ALT carries only EID-prefixes, used to a 732 construct BGP path to each ETR (or Map-Server) that originates each 733 prefix; the ALT does not carry reachability about RLOCs. In 734 addition, EID-prefix information may be aggregated as the topology 735 and address assignment hierarchy allow. Since the topology is all 736 tunneled and can be modified as needed, reasonably good aggregation 737 should be possible. In addition, since most ETRs are expected to 738 connect to the ALT using the Map Server interface, Map Servers will 739 implement a natural "edge" for the ALT where dampening and 740 aggregation can be applied. For these reasons, the set of prefix 741 information on the ALT can be expected to be both better aggregated 742 and considerably less volatile than the actual EID-to-RLOC mappings. 744 7.4. EID assignment flexibility vs. ALT scaling 746 There are major open questions regarding how the ALT will be deployed 747 and what organization(s) will operate it. In a simple, non- 748 distributed world, centralized administration of EID prefix 749 assignment and ALT network design would facilitate a well- aggregated 750 ALT routing system. Business and other realities will likely result 751 in a more complex, distributed system involving multiple levels of 752 prefix delegation, multiple operators of parts of the ALT 753 infrastructure, and a combination of competition and cooperation 754 among the participants. In addition, re-use of existing IP address 755 assignments, both "PI" and "PA", to avoid renumbering when sites 756 transition to LISP will further complicate the processes of building 757 and operating the ALT. 759 A number of conflicting considerations need to be kept in mind when 760 designing and building the ALT. Among them are: 762 1. Target ALT routing state size and level of aggregation. As 763 described in Section 7.1, the ALT should not suffer from some of 764 the performance constraints or stability issues as the Internet 765 global routing system, so some reasonable level of deaggregation 766 and increased number of EID prefixes beyond what might be 767 considered ideal should be acceptable. That said, measures, such 768 as tunnel rehoming to preserve aggregation when sites move from 769 one mapping provider to another and implementing aggregation at 770 multiple levels in the hierarchy to collapse de-aggregation at 771 lower levels, should be taken to reduce unnecessary explosion of 772 ALT routing state. 774 2. Number of operators of parts of the ALT and how they will be 775 organized (hierarchical delegation vs. shared administration). 776 This will determine not only how EID prefixes are assigned but 777 also how tunnels are configured and how EID prefixes can be 778 aggregated between different parts of the ALT. 780 3. Number of connections between different parts of the ALT. Trade- 781 offs will need to be made among resilience, performance, and 782 placement of aggregation boundaries. 784 4. EID prefix portability between competing operators of the ALT 785 infrastructure. A significant benefit for an end-site to adopt 786 LISP is the availability of EID space that is not tied to a 787 specific connectivity provider; it is important to ensure that an 788 end site doesn't trade lock-in to a connectivity provider for 789 lock-in to a provider of its EID assignment, ALT connectivity, or 790 Map Server facilities. 792 This is, by no means, and exhaustive list. 794 While resolving these issues is beyond the scope of this document, 795 the authors recommend that existing distributed resource structures, 796 such as the IANA/Regional Internet Registries and the ICANN/Domain 797 Registrar, be carefully considered when designing and deploying the 798 ALT infrastructure. 800 8. Connecting sites to the ALT network 802 8.1. ETRs originating information into the ALT 804 EID-prefix information is originated into the ALT by three different 805 mechanisms: 807 Map Server: In most cases, a site will configure its ETR(s) to 808 register with one or more Map Servers (see [LISP-MS]), and does 809 not participate directly in the ALT. 811 BGP: For a site requiring complex control over their EID-prefix 812 origination into the ALT, an ETR may connect to the LISP+ALT 813 overlay network by running BGP to one or more ALT Router(s) over 814 tunnel(s). The ETR advertises reachability for its EID-prefixes 815 over these BGP connection(s). The edge ALT Router(s) that 816 receive(s) these prefixes then propagate(s) them into the ALT. 817 Here the ETR is simply an BGP peer of ALT Router(s) at the edge of 818 the ALT. Where possible, an ALT Router that receives EID-prefixes 819 from an ETR via BGP should aggregate that information. 821 Configuration: One or more ALT Router(s) may be configured to 822 originate an EID-prefix on behalf of the non-BGP-speaking ETR that 823 is authoritative for a prefix. As in the case above, the ETR is 824 connected to ALT Router(s) using GRE tunnel(s) but rather than BGP 825 being used, the ALT Router(s) are configured with what are in 826 effect "static routes" for the EID-prefixes "owned" by the ETR. 827 The GRE tunnel is used to route Map-Requests to the ETR. 829 Note: in all cases, an ETR may register to multiple Map Servers or 830 connect to multiple ALT Routers for the following reasons: 832 * redundancy, so that a particular ETR is still reachable even if 833 one path or tunnel is unavailable. 835 * to connect to different parts of the ALT hierarchy if the ETR 836 "owns" multiple EID-to-RLOC mappings for EID-prefixes that 837 cannot be aggregated by the same ALT Router (i.e. are not 838 topologically "close" to each other in the ALT). 840 8.2. ITRs Using the ALT 842 In the common configuration, an ITR does not need to know anything 843 about the ALT, since it sends Map-Requests to one of its configured 844 Map-Resolvers (see [LISP-MS]). There are two exceptional cases: 846 Static default: If a Map Resolver is not available but an ITR is 847 adjacent to an ALT Router (either over a common subnet or through 848 the use of a tunnel), it can use an ALT Default Route route to 849 cause all ALT Datagrams to be sent that ALT Router. This case is 850 expected to be rare. 852 Connection to ALT: A site with complex Internet connectivity needs 853 may need more fine-grained distinction between traffic to LISP- 854 capable and non-LISP-capable sites. Such a site may configure 855 each of its ITRs to connect directly to the ALT, using a tunnel 856 and BGP connection. In this case, the ITR will receive EID-prefix 857 routes from its BGP connection to the ALT Router and will LISP- 858 encapsulate and send ALT Datagrams through the tunnel to the ALT 859 Router. Traffic to other destinations may be forwarded (without 860 LISP encapsulation) to non-LISP next-hop routers that the ITR 861 knows. 863 In general, an ITR that connects to the ALT does so only to to ALT 864 Routers at the "edge" of the ALT (typically two for redundancy). 865 There may, though, be situations where an ITR would connect to 866 other ALT Routers to receive additional, shorter path information 867 about a portion of the ALT of interest to it. This can be 868 accomplished by establishing GRE tunnels between the ITR and the 869 set of ALT Routers with the additional information. This is a 870 purely local policy issue between the ITR and the ALT Routers in 871 question. 873 As described in [LISP-MS], Map-Resolvers do not accept or forward 874 Data Probes; in the rare scenario that an ITR does support and 875 originate Data Probes, it must do so using one of the exceptional 876 configurations described above. Note that the use of Data Probes is 877 discouraged at this time (see Section 3.3). 879 9. IANA Considerations 881 This document makes no request of the IANA. 883 10. Security Considerations 885 LISP+ALT shares many of the security characteristics of BGP. Its 886 security mechanisms are comprised of existing technologies in wide 887 operational use today, so securing the ALT should be mostly a matter 888 of applying the same technology that is used to secure the BGP-based 889 global routing system (see Section 10.3 below). 891 10.1. Apparent LISP+ALT Vulnerabilities 893 This section briefly lists the known potential vulnerabilities of 894 LISP+ALT. 896 Mapping Integrity: Can an attacker insert bogus mappings to black- 897 hole (create Denial-of-Service, or DoS attack) or intercept LISP 898 data-plane packets? 900 ALT Router Availability: Can an attacker DoS the ALT Routers 901 connected to a given ETR? If a site's ETR cannot advertise its 902 EID-to-RLOC mappings, the site is essentially unavailable. 904 ITR Mapping/Resources: Can an attacker force an ITR or ALT Router to 905 drop legitimate mapping requests by flooding it with random 906 destinations for which it will generate large numbers of Map- 907 Requests and fill its mapping cache? Further study is required to 908 see the impact of admission control on the overlay network. 910 EID Map-Request Exploits for Reconnaissance: Can an attacker learn 911 about a LISP site's TE policy by sending legitimate mapping 912 requests and then observing the RLOC mapping replies? Is this 913 information useful in attacking or subverting peer relationships? 914 Note that any public LISP mapping database will have similar data- 915 plane reconnaissance issue. 917 Scaling of ALT Router Resources: Paths through the ALT may be of 918 lesser bandwidth than more "direct" paths; this may make them more 919 prone to high-volume denial-of-service attacks. For this reason, 920 all components of the ALT (ETRs and ALT Routers) should be 921 prepared to rate-limit traffic (ALT Datagrams) that could be 922 received across the ALT. 924 UDP Map-Reply from ETR: Since Map-Replies are sent directly from the 925 ETR to the ITR's RLOC, the ITR's RLOC may be vulnerable to various 926 types of DoS attacks (this is a general property of LISP, not an 927 LISP+ALT vulnerability). 929 More-specific prefix leakage: Because EID-prefixes on the ALT are 930 expected to be fairly well-aggregated and EID-prefixes propagated 931 out to the global Internet (see [LISP-IW] much more so, accidental 932 leaking or malicious advertisement of an EID-prefix into the 933 global routing system could cause traffic redirection away from a 934 LISP site. This is not really a new problem, though, and its 935 solution can only be achieved by much more strict prefix filtering 936 and authentication on the global routing system. 938 10.2. Survey of LISP+ALT Security Mechanisms 940 Explicit peering: The devices themselves can both prioritize 941 incoming packets, as well as potentially do key checks in hardware 942 to protect the control plane. 944 Use of TCP to connect elements: This makes it difficult for third 945 parties to inject packets. 947 Use of HMAC Protected BGP/TCP Connections: HMAC is used to verify 948 message integrity and authenticity, making it nearly impossible 949 for third party devices to either insert or modify messages. 951 Message Sequence Numbers and Nonce Values in Messages: This allows 952 an ITR to verify that the Map-Reply from an ETR is in response to 953 a Map-Request originated by that ITR (this is a general property 954 of LISP; LISP+ALT does not change this behavior). 956 10.3. Use of new IETF standard BGP Security mechanisms 958 LISP+ALT's use of BGP allows the ALT to take advantage of BGP 959 security features designed for existing Internet BGP use. Should the 960 Internet community converge on the work currently being done in the 961 IETF SIDR working group or should either S-BGP [I-D.murphy-bgp-secr] 962 or soBGP [I-D.white-sobgparchitecture] be implemented and widely- 963 deployed, LISP+ALT can readily use these mechanisms to provide 964 authentication of EID-prefix origination and EID-to-RLOC mappings. 966 11. Acknowledgments 968 The authors would like to specially thank J. Noel Chiappa who was a 969 key contributer to the design of the LISP-CONS mapping database (many 970 ideas from which made their way into LISP+ALT) and who has continued 971 to provide invaluable insight as the LISP effort has evolved. Others 972 who have provided valuable contributions include John Zwiebel, Hannu 973 Flinck, Amit Jain, John Scudder, and Scott Brim. 975 12. References 977 12.1. Normative References 979 [LISP] Farinacci, D., Fuller, V., Meyer, D., and D. Lewis, 980 "Locator/ID Separation Protocol (LISP)", 981 draft-ietf-lisp-10.txt (work in progress), March 2011. 983 [LISP-MS] Fuller, V. and D. Farinacci, "LISP Map Server", 984 draft-ietf-lisp-ms-07.txt (work in progress), March 2011. 986 [RFC2784] Farinacci, D., Li, T., Hanks, S., Meyer, D., and P. 987 Traina, "Generic Routing Encapsulation (GRE)", RFC 2784, 988 March 2000. 990 [RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway 991 Protocol 4 (BGP-4)", RFC 4271, January 2006. 993 [RFC4632] Fuller, V. and T. Li, "Classless Inter-domain Routing 994 (CIDR): The Internet Address Assignment and Aggregation 995 Plan", BCP 122, RFC 4632, August 2006. 997 [RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter, 998 "Multiprotocol Extensions for BGP-4", RFC 4760, 999 January 2007. 1001 12.2. Informative References 1003 [I-D.murphy-bgp-secr] 1004 Murphy, S., "BGP Security Analysis", 1005 draft-murphy-bgp-secr-04 (work in progress), 1006 November 2001. 1008 [I-D.white-sobgparchitecture] 1009 White, R., "Architecture and Deployment Considerations for 1010 Secure Origin BGP (soBGP)", 1011 draft-white-sobgparchitecture-00 (work in progress), 1012 May 2004. 1014 [LISP-IW] Lewis, D., Meyer, D., Farinacci, D., and V. Fuller, 1015 "Interworking LISP with IPv4 and ipv6", 1016 draft-ietf-lisp-interworking-02.txt (work in progress), 1017 March 2011. 1019 Authors' Addresses 1021 Vince Fuller 1022 Cisco 1023 Tasman Drive 1024 San Jose, CA 95134 1025 USA 1027 Email: vaf@cisco.com 1029 Dino Farinacci 1030 Cisco 1031 Tasman Drive 1032 San Jose, CA 95134 1033 USA 1035 Email: dino@cisco.com 1037 Dave Meyer 1038 Cisco 1039 Tasman Drive 1040 San Jose, CA 95134 1041 USA 1043 Email: dmm@cisco.com 1045 Darrel Lewis 1046 Cisco 1047 Tasman Drive 1048 San Jose, CA 95134 1049 USA 1051 Email: darlewis@cisco.com