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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Downref: Normative reference to an Informational RFC: RFC 7908 Summary: 1 error (**), 0 flaws (~~), 0 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group A. Azimov 3 Internet-Draft Qrator Labs & Yandex 4 Intended status: Standards Track E. Bogomazov 5 Expires: 3 October 2022 Qrator Labs 6 R. Bush 7 Internet Initiative Japan & Arrcus, Inc. 8 K. Patel 9 Arrcus 10 K. Sriram 11 USA NIST 12 1 April 2022 14 Route Leak Prevention and Detection using Roles in UPDATE and OPEN 15 Messages 16 draft-ietf-idr-bgp-open-policy-24 18 Abstract 20 Route leaks are the propagation of BGP prefixes that violate 21 assumptions of BGP topology relationships, e.g., announcing a route 22 learned from one transit provider to another transit provider or a 23 lateral (i.e., non-transit) peer or announcing a route learned from 24 one lateral peer to another lateral peer or a transit provider. 25 These are usually the result of misconfigured or absent BGP route 26 filtering or lack of coordination between autonomous systems (ASes). 27 Existing approaches to leak prevention rely on marking routes by 28 operator configuration, with no check that the configuration 29 corresponds to that of the eBGP neighbor, or enforcement that the two 30 eBGP speakers agree on the peering relationship. This document 31 enhances the BGP OPEN message to establish an agreement of the 32 peering relationship on each eBGP session between autonomous systems 33 in order to enforce appropriate configuration on both sides. 34 Propagated routes are then marked according to the agreed 35 relationship, allowing both prevention and detection of route leaks. 37 Requirements Language 39 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 40 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 41 "OPTIONAL" in this document are to be interpreted as described in 42 BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all 43 capitals, as shown here. 45 Status of This Memo 47 This Internet-Draft is submitted in full conformance with the 48 provisions of BCP 78 and BCP 79. 50 Internet-Drafts are working documents of the Internet Engineering 51 Task Force (IETF). Note that other groups may also distribute 52 working documents as Internet-Drafts. The list of current Internet- 53 Drafts is at https://datatracker.ietf.org/drafts/current/. 55 Internet-Drafts are draft documents valid for a maximum of six months 56 and may be updated, replaced, or obsoleted by other documents at any 57 time. It is inappropriate to use Internet-Drafts as reference 58 material or to cite them other than as "work in progress." 60 This Internet-Draft will expire on 3 October 2022. 62 Copyright Notice 64 Copyright (c) 2022 IETF Trust and the persons identified as the 65 document authors. All rights reserved. 67 This document is subject to BCP 78 and the IETF Trust's Legal 68 Provisions Relating to IETF Documents (https://trustee.ietf.org/ 69 license-info) in effect on the date of publication of this document. 70 Please review these documents carefully, as they describe your rights 71 and restrictions with respect to this document. Code Components 72 extracted from this document must include Revised BSD License text as 73 described in Section 4.e of the Trust Legal Provisions and are 74 provided without warranty as described in the Revised BSD License. 76 Table of Contents 78 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 79 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 80 2.1. Peering Relationships . . . . . . . . . . . . . . . . . . 4 81 3. BGP Role . . . . . . . . . . . . . . . . . . . . . . . . . . 5 82 3.1. BGP Role Capability . . . . . . . . . . . . . . . . . . . 5 83 3.2. Role Correctness . . . . . . . . . . . . . . . . . . . . 6 84 4. BGP Only to Customer (OTC) Attribute . . . . . . . . . . . . 8 85 5. Additional Considerations . . . . . . . . . . . . . . . . . . 10 86 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 87 7. Security Considerations . . . . . . . . . . . . . . . . . . . 11 88 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 89 8.1. Normative References . . . . . . . . . . . . . . . . . . 12 90 8.2. Informative References . . . . . . . . . . . . . . . . . 13 91 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 14 92 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 14 93 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14 95 1. Introduction 97 Route leaks are the propagation of BGP prefixes that violate 98 assumptions of BGP topology relationships, e.g., announcing a route 99 learned from one transit provider to another transit provider or a 100 lateral (i.e., non-transit) peer or announcing a route learned from 101 one lateral peer to another lateral peer or a transit provider 102 [RFC7908]. These are usually the result of misconfigured or absent 103 BGP route filtering or lack of coordination between autonomous 104 systems (ASes). 106 Existing approaches to leak prevention rely on marking routes by 107 operator configuration, with no check that the configuration 108 corresponds to that of the eBGP neighbor, or enforcement that the two 109 eBGP speakers agree on the relationship. This document enhances the 110 BGP OPEN message to establish an agreement of the relationship on 111 each eBGP session between autonomous systems in order to enforce 112 appropriate configuration on both sides. Propagated routes are then 113 marked according to the agreed relationship, allowing both prevention 114 and detection of route leaks. 116 This document specifies a means of replacing the operator-driven 117 configuration-based method of route leak prevention, described above, 118 with an in-band method for route leak prevention and detection. 120 This method uses a new configuration parameter, BGP Role, which is 121 negotiated using a BGP Role Capability in the OPEN message [RFC5492]. 122 An eBGP speaker may require the use of this capability and 123 confirmation of BGP Role with a neighbor for the BGP OPEN to succeed. 125 An optional, transitive BGP Path Attribute, called Only to Customer 126 (OTC), is specified in Section 4. It prevents ASes from creating 127 leaks and detects leaks created by the ASes in the middle of an AS 128 path. The main focus/applicability is the Internet (IPv4 and IPv6 129 unicast route advertisements). 131 2. Terminology 133 The terms "local AS" and "remote AS" are used to refer to the two 134 ends of an eBGP session. The "local AS" is the AS where the protocol 135 action being described is to be performed, and "remote AS" is the AS 136 at the other end of the eBGP session in consideration. 138 The use of the term "route is ineligible" in this document has the 139 same meaning as in [RFC4271], i.e., "route is ineligible to be 140 installed in Loc-RIB and will be excluded from the next phase of 141 route selection." 143 2.1. Peering Relationships 145 The terms for peering relationships defined and used in this document 146 (see below) do not necessarily represent business relationships based 147 on payment agreements. These terms are used to represent 148 restrictions on BGP route propagation, sometimes known as the Gao- 149 Rexford model [Gao]. The terms Provider, Customer, and Peer used 150 here are synonymous to the terms "transit provider", "customer", and 151 "lateral (i.e., non-transit) peer", respectively, used in [RFC7908]. 153 The following is a list of BGP Roles for eBGP peering and the 154 corresponding rules for route propagation: 156 Provider: MAY propagate any available route to a Customer. 158 Customer: MAY propagate any route learned from a Customer, or 159 locally originated, to a Provider. All other routes MUST NOT be 160 propagated. 162 Route Server (RS): MAY propagate any available route to a Route 163 Server Client (RS-Client). 165 Route Server Client (RS-Client): MAY propagate any route learned 166 from a Customer, or locally originated, to an RS. All other 167 routes MUST NOT be propagated. 169 Peer: MAY propagate any route learned from a Customer, or locally 170 originated, to a Peer. All other routes MUST NOT be propagated. 172 If the local AS has one of the above Roles (in the order shown), then 173 the corresponding peering relationship with the remote AS is 174 Provider-to-Customer, Customer-to-Provider, RS-to-RS-Client, RS- 175 Client-to-RS, or Peer-to-Peer (i.e., lateral peers), respectively. 176 These are called normal peering relationships. 178 If the local AS has more than one peering role with the remote AS 179 such peering relation is called Complex. An example is when the 180 peering relationship is Provider-to-Customer for some prefixes while 181 it is Peer-to-Peer for other prefixes [Gao]. 183 A BGP speaker may apply policy to reduce what is announced, and a 184 recipient may apply policy to reduce the set of routes they accept. 186 Violation of the route propagation rules listed above may result in 187 route leaks [RFC7908]. Automatic enforcement of these rules should 188 significantly reduce route leaks that may otherwise occur due to 189 manual configuration mistakes. 191 As specified in Section 4, the Only to Customer (OTC) Attribute is 192 used to identify all the routes in the AS that have been received 193 from a Peer, Provider, or RS. 195 3. BGP Role 197 The BGP Role characterizes the relationship between the eBGP speakers 198 forming a session. One of the Roles described below SHOULD be 199 configured at the local AS for each eBGP session (see definitions in 200 Section 2) based on the local AS's knowledge of its Role. The only 201 exception is when the eBGP connection is Complex (see Section 5). 202 BGP Roles are mutually confirmed using the BGP Role Capability 203 (described in Section 3.1) on each eBGP session. 205 Allowed Roles for eBGP sessions are: 207 * Provider - the local AS is a transit Provider of the remote AS; 209 * Customer - the local AS is a transit Customer of the remote AS; 211 * RS - the local AS is a Route Server (usually at an Internet 212 exchange point) and the remote AS is its RS-Client; 214 * RS-Client - the local AS is a client of an RS and the RS is the 215 remote AS; 217 * Peer - the local and remote ASes are Peers (i.e., have a lateral 218 peering relationship). 220 3.1. BGP Role Capability 222 The BGP Role Capability is defined as follows: 224 * Code - 9 226 * Length - 1 (octet) 228 * Value - integer corresponding to speaker's BGP Role (see Table 1). 230 +=======+==============================+ 231 | Value | Role name (for the local AS) | 232 +=======+==============================+ 233 | 0 | Provider | 234 +-------+------------------------------+ 235 | 1 | RS | 236 +-------+------------------------------+ 237 | 2 | RS-Client | 238 +-------+------------------------------+ 239 | 3 | Customer | 240 +-------+------------------------------+ 241 | 4 | Peer (i.e., Lateral Peer) | 242 +-------+------------------------------+ 243 | 5-255 | Unassigned | 244 +-------+------------------------------+ 246 Table 1: Predefined BGP Role Values 248 If BGP Role is locally configured, the eBGP speaker MUST advertise 249 BGP Role Capability in the BGP OPEN message. An eBGP speaker MUST 250 NOT advertise multiple versions of the BGP Role Capability. The 251 error handling when multiple BGP Role Capabilities are received is 252 described in Section 3.2. 254 3.2. Role Correctness 256 Section 3.1 described how BGP Role encodes the relationship on each 257 eBGP session between autonomous systems (ASes). 259 The mere receipt of BGP Role Capability does not automatically 260 guarantee the Role agreement between two eBGP neighbors. If the BGP 261 Role Capability is advertised, and one is also received from the 262 peer, the Roles MUST correspond to the relationships in Table 2. If 263 the Roles do not correspond, the BGP speaker MUST reject the 264 connection using the Role Mismatch Notification (code 2, subcode 265 TBD). 267 +===============+================+ 268 | Local AS Role | Remote AS Role | 269 +===============+================+ 270 | Provider | Customer | 271 +---------------+----------------+ 272 | Customer | Provider | 273 +---------------+----------------+ 274 | RS | RS-Client | 275 +---------------+----------------+ 276 | RS-Client | RS | 277 +---------------+----------------+ 278 | Peer | Peer | 279 +---------------+----------------+ 281 Table 2: Allowed Pairs of Role 282 Capabilities 284 For backward compatibility, if the BGP Role Capability is sent but 285 one is not received, the BGP Speaker SHOULD ignore the absence of the 286 BGP Role Capability and proceed with session establishment. The 287 locally configured BGP Role is used for the procedures described in 288 Section 4. 290 An operator may choose to apply a "strict mode" in which the receipt 291 of a BGP Role Capability from the remote AS is required. When 292 operating in the "strict mode", if the BGP Role Capability is sent, 293 but one is not received, then the connection is rejected using the 294 Role Mismatch Notification (code 2, subcode TBD). See comments in 295 Section 7. 297 If an eBGP speaker receives multiple but identical BGP Role 298 Capabilities with the same value in each, then the speaker considers 299 them to be a single BGP Role Capability and proceeds [RFC5492]. If 300 multiple BGP Role Capabilities are received and not all of them have 301 the same value, then the BGP speaker MUST reject the connection using 302 the Role Mismatch Notification (code 2, subcode TBD). 304 The BGP Role value for the local AS (in conjunction with the OTC 305 Attribute in the received UPDATE message) is used in the route leak 306 prevention and detection procedures described in Section 4. 308 4. BGP Only to Customer (OTC) Attribute 310 The Only to Customer (OTC) Attribute is an optional transitive path 311 attribute of the UPDATE message with Attribute Type Code 35 and a 312 length of 4 octets. The purpose of this attribute is to enforce that 313 once a route is sent to a Customer, Peer, or RS-Client (see 314 definitions in Section 2.1), it will subsequently go only to 315 Customers. The attribute value is an AS number (ASN) determined by 316 the procedures described below. 318 The following ingress procedure applies to the processing of the OTC 319 Attribute on route receipt: 321 1. If a route with the OTC Attribute is received from a Customer or 322 RS-Client, then it is a route leak and MUST be considered 323 ineligible (see Section 2). 325 2. If a route with the OTC Attribute is received from a Peer (i.e., 326 remote AS with a Peer Role) and the Attribute has a value that is 327 not equal to the remote (i.e., Peer's) AS number, then it is a 328 route leak and MUST be considered ineligible. 330 3. If a route is received from a Provider, Peer, or RS, and the OTC 331 Attribute is not present, then it MUST be added with a value 332 equal to the AS number of the remote AS. 334 The following egress procedure applies to the processing of the OTC 335 Attribute on route advertisement: 337 1. If a route is to be advertised to a Customer, Peer, or RS-Client 338 (when the sender is an RS), and the OTC Attribute is not present, 339 then when advertising the route, an OTC Attribute MUST be added 340 with a value equal to the AS number of the local AS. 342 2. If a route already contains the OTC Attribute, it MUST NOT be 343 propagated to Providers, Peers, or RS(s). 345 The above-described procedures provide both leak prevention for the 346 local AS and leak detection and mitigation multiple hops away. In 347 the case of prevention at the local AS, the presence of an OTC 348 Attribute indicates to the egress router that the route was learned 349 from a Peer, Provider, or RS, and it can be advertised only to the 350 customers. The same OTC Attribute which is set locally also provides 351 a way to detect route leaks by an AS multiple hops away if a route is 352 received from a Customer, Peer, or RS-Client. For example, if an AS 353 sets the OTC Attribute on a route sent to a Peer and the route is 354 subsequently received by a compliant AS from a Customer, then the 355 receiving AS detects (based on the presence of the OTC Attribute) 356 that the route is a leak. 358 The OTC Attribute might be set at the egress of the remote AS or at 359 the ingress of the local AS, i.e., if the remote AS is non-compliant 360 with this specification, then the local AS will have to set the OTC 361 Attribute if it is absent. In both scenarios, the OTC value will be 362 the same. This makes the scheme more robust and benefits early 363 adopters. 365 The OTC Attribute is considered malformed if the length value is not 366 4. An UPDATE message with a malformed OTC Attribute SHALL be handled 367 using the approach of "treat-as-withdraw" [RFC7606]. 369 The BGP Role negotiation and OTC Attribute based procedures specified 370 in this document are NOT RECOMMENDED to be used between autonomous 371 systems in an AS Confederation [RFC5065]. If an OTC Attribute is 372 added on egress from the AS Confederation, its value MUST equal the 373 AS Confederation Identifier. Also, on egress from the AS 374 Confederation, an UPDATE MUST NOT contain an OTC Attribute with a 375 value corresponding to any Member-AS Number other than the AS 376 Confederation Identifier. 378 The procedures specified in this document in scenarios that use 379 private AS numbers behind an Internet-facing ASN (e.g., a data center 380 network [RFC7938] or stub customer) may be used, but any details are 381 outside the scope of this document. On egress from the Internet- 382 facing AS, the OTC Attribute MUST NOT contain a value other than the 383 Internet-facing ASN. 385 Once the OTC Attribute has been set, it MUST be preserved unchanged 386 (this also applies to an AS Confederation). 388 The described ingress and egress procedures are applicable only for 389 the address families AFI 1 (IPv4) and AFI 2 (IPv6) with SAFI 1 390 (unicast) in both cases and MUST NOT be applied to other address 391 families by default. The operator MUST NOT have the ability to 392 modify the procedures defined in this section. 394 5. Additional Considerations 396 Roles MUST NOT be configured on an eBGP session with a Complex 397 peering relationship. If multiple eBGP sessions can segregate the 398 Complex peering relationship into eBGP sessions with normal peering 399 relationships, BGP Roles SHOULD be used on each of the resulting eBGP 400 sessions. 402 An operator may want to achieve an equivalent outcome by configuring 403 policies on a per-prefix basis to follow the definitions of peering 404 relations as described in Section 2.1. However, in this case, there 405 are no in-band measures to check the correctness of the per-prefix 406 peering configuration. 408 The incorrect setting of BGP Roles and/or OTC Attributes may affect 409 prefix propagation. Further, this document does not specify any 410 special handling of an incorrect AS number in the OTC Attribute. 412 In AS migration scenarios [RFC7705], a given router may represent 413 itself as any one of several different ASes. This should not be a 414 problem since the egress procedures in Section 4 specify that the OTC 415 Attribute is to be attached as part of route transmission. 416 Therefore, a router is expected to set the OTC value equal to the ASN 417 it is currently representing itself as. 419 Section 6 of [RFC7606] documents possible negative impacts of "treat- 420 as-withdraw" behavior. Such negative impacts may include forwarding 421 loops or blackholes. It also discusses debugging considerations 422 related to this behavior. 424 6. IANA Considerations 426 IANA has registered a new BGP Capability (Section 3.1) in the 427 "Capability Codes" registry's "IETF Review" range [RFC5492]. The 428 description for the new capability is "BGP Role". IANA has assigned 429 the value 9 [to be removed upon publication: 430 https://www.iana.org/assignments/capability-codes/capability- 431 codes.xhtml]. This document is the reference for the new capability. 433 The BGP Role capability includes a Value field, for which IANA is 434 requested to create and maintain a new sub-registry called "BGP Role 435 Value" in the Capability Codes registry. Assignments consist of a 436 Value and a corresponding Role name. Initially, this registry is to 437 be populated with the data contained in Table 1 found in Section 3.1. 438 Future assignments may be made by the "IETF Review" policy as defined 439 in [RFC8126]. The registry is as shown in Table 3. 441 +=======+===============================+===============+ 442 | Value | Role name (for the local AS) | Reference | 443 +=======+===============================+===============+ 444 | 0 | Provider | This document | 445 +-------+-------------------------------+---------------+ 446 | 1 | RS | This document | 447 +-------+-------------------------------+---------------+ 448 | 2 | RS-Client | This document | 449 +-------+-------------------------------+---------------+ 450 | 3 | Customer | This document | 451 +-------+-------------------------------+---------------+ 452 | 4 | Peer (i.e., Lateral Peer) | This document | 453 +-------+-------------------------------+---------------+ 454 | 5-255 | To be assigned by IETF Review | | 455 +-------+-------------------------------+---------------+ 457 Table 3: IANA Registry for BGP Role 459 IANA has registered a new OPEN Message Error subcode named the "Role 460 Mismatch" (see Section 3.2) in the OPEN Message Error subcodes 461 registry. IANA has assigned the value 11 [to be removed upon 462 publication: https://www.iana.org/assignments/bgp-parameters/bgp- 463 parameters.xhtml#bgp-parameters-6]. This document is the reference 464 for the new subcode. 466 Due to improper use of the values 8, 9, and 10 in the OPEN Message 467 Error subcodes registry, this document requested IANA to mark these 468 values as "Deprecated". IANA has marked values 8-10 as "Deprecated" 469 in the OPEN Message Error subcodes registry. This document is listed 470 as the reference. 472 IANA has also registered a new path attribute named "Only to Customer 473 (OTC)" (see Section 4) in the "BGP Path Attributes" registry. IANA 474 has assigned code value 35 [To be removed upon publication: 475 http://www.iana.org/assignments/bgp-parameters/bgp- 476 parameters.xhtml#bgp-parameters-2]. This document is the reference 477 for the new attribute. 479 7. Security Considerations 481 The security considerations of BGP (as specified in [RFC4271] and 482 [RFC4272]) apply. 484 This document proposes a mechanism using BGP Role for the prevention 485 and detection of route leaks that are the result of BGP policy 486 misconfiguration. A misconfiguration of the BGP Role may affect 487 prefix propagation. For example, if a downstream (i.e., towards a 488 Customer) peering link were misconfigured with a Provider or Peer 489 Role, this will limit the number of prefixes that can be advertised 490 in this direction. On the other hand, if an upstream provider were 491 misconfigured (by a local AS) with the Customer Role, this may result 492 in propagating routes that are received from other Providers or 493 Peers. But the BGP Role negotiation and the resulting confirmation 494 of Roles make such misconfigurations unlikely. 496 Setting the strict mode of operation for BGP Role negotiation as the 497 default may result in a situation where the eBGP session will not 498 come up after a software update. Implementations with such default 499 behavior are strongly discouraged. 501 Removing the OTC Attribute or changing its value can limit the 502 opportunity for route leak detection. Such activity can be done on 503 purpose as part of an on-path attack. For example, an AS can remove 504 the OTC Attribute on a received route and then leak the route to its 505 transit provider. This kind of threat is not new in BGP and it may 506 affect any Attribute (Note: BGPsec [RFC8205] offers protection only 507 for the AS_PATH Attribute). 509 Adding an OTC Attribute when the route is advertised from Customer to 510 Provider will limit the propagation of the route. Such a route may 511 be considered as ineligible by the immediate Provider or its Peers or 512 upper layer Providers. This kind of OTC Attribute addition is 513 unlikely to happen on the Provider side because it will limit the 514 traffic volume towards its Customer. On the Customer side, adding an 515 OTC Attribute for traffic engineering purposes is also discouraged 516 because it will limit route propagation in an unpredictable way. 518 8. References 520 8.1. Normative References 522 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 523 Requirement Levels", BCP 14, RFC 2119, 524 DOI 10.17487/RFC2119, March 1997, 525 . 527 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 528 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 529 DOI 10.17487/RFC4271, January 2006, 530 . 532 [RFC5065] Traina, P., McPherson, D., and J. Scudder, "Autonomous 533 System Confederations for BGP", RFC 5065, 534 DOI 10.17487/RFC5065, August 2007, 535 . 537 [RFC5492] Scudder, J. and R. Chandra, "Capabilities Advertisement 538 with BGP-4", RFC 5492, DOI 10.17487/RFC5492, February 539 2009, . 541 [RFC7606] Chen, E., Ed., Scudder, J., Ed., Mohapatra, P., and K. 542 Patel, "Revised Error Handling for BGP UPDATE Messages", 543 RFC 7606, DOI 10.17487/RFC7606, August 2015, 544 . 546 [RFC7908] Sriram, K., Montgomery, D., McPherson, D., Osterweil, E., 547 and B. Dickson, "Problem Definition and Classification of 548 BGP Route Leaks", RFC 7908, DOI 10.17487/RFC7908, June 549 2016, . 551 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 552 Writing an IANA Considerations Section in RFCs", BCP 26, 553 RFC 8126, DOI 10.17487/RFC8126, June 2017, 554 . 556 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 557 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 558 May 2017, . 560 8.2. Informative References 562 [Gao] Gao, L. and J. Rexford, "Stable Internet routing without 563 global coordination", IEEE/ACM Transactions on 564 Networking, Volume 9, Issue 6, pp 689-692, DOI 565 10.1109/90.974523, December 2001, 566 . 568 [RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis", 569 RFC 4272, DOI 10.17487/RFC4272, January 2006, 570 . 572 [RFC7705] George, W. and S. Amante, "Autonomous System Migration 573 Mechanisms and Their Effects on the BGP AS_PATH 574 Attribute", RFC 7705, DOI 10.17487/RFC7705, November 2015, 575 . 577 [RFC7938] Lapukhov, P., Premji, A., and J. Mitchell, Ed., "Use of 578 BGP for Routing in Large-Scale Data Centers", RFC 7938, 579 DOI 10.17487/RFC7938, August 2016, 580 . 582 [RFC8205] Lepinski, M., Ed. and K. Sriram, Ed., "BGPsec Protocol 583 Specification", RFC 8205, DOI 10.17487/RFC8205, September 584 2017, . 586 Acknowledgments 588 The authors wish to thank Alvaro Retana, Bruno Decraene, Jeff Haas, 589 John Scudder, Sue Hares, Ben Maddison, Andrei Robachevsky, Daniel 590 Ginsburg, Ruediger Volk, Pavel Lunin, Gyan Mishra, and Ignas Bagdonas 591 for review, comments, and suggestions during the course of this work. 592 Thanks are also due to many IESG reviewers whose comments greatly 593 helped improve the clarity, accuracy, and presentation in the 594 document. 596 Contributors 598 Brian Dickson 599 Independent 600 Email: brian.peter.dickson@gmail.com 602 Doug Montgomery 603 USA National Institute of Standards and Technology 604 Email: dougm@nist.gov 606 Authors' Addresses 608 Alexander Azimov 609 Qrator Labs & Yandex 610 Ulitsa Lva Tolstogo 16 611 Moscow 612 119021 613 Russian Federation 614 Email: a.e.azimov@gmail.com 616 Eugene Bogomazov 617 Qrator Labs 618 1-y Magistralnyy tupik 5A 619 Moscow 620 123290 621 Russian Federation 622 Email: eb@qrator.net 624 Randy Bush 625 Internet Initiative Japan & Arrcus, Inc. 626 5147 Crystal Springs 627 Bainbridge Island, Washington 98110 628 United States of America 629 Email: randy@psg.com 630 Keyur Patel 631 Arrcus 632 2077 Gateway Place, Suite #400 633 San Jose, CA 95119 634 United States of America 635 Email: keyur@arrcus.com 637 Kotikalapudi Sriram 638 USA National Institute of Standards and Technology 639 100 Bureau Drive 640 Gaithersburg, MD 20899 641 United States of America 642 Email: ksriram@nist.gov