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Heitz, Ed. 3 Internet-Draft Cisco 4 Intended status: Standards Track J. Snijders, Ed. 5 Expires: June 5, 2017 NTT 6 K. Patel 7 Arrcus 8 I. Bagdonas 9 Equinix 10 N. Hilliard 11 INEX 12 December 2, 2016 14 BGP Large Communities 15 draft-ietf-idr-large-community-10 17 Abstract 19 This document describes the BGP Large Communities attribute, an 20 extension to BGP-4. This attribute provides a mechanism to signal 21 opaque information within separate namespaces to aid in routing 22 management. The attribute is suitable for use with four-octet 23 Autonomous System Numbers. 25 Requirements Language 27 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 28 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 29 document are to be interpreted as described in [RFC2119]. 31 Status of This Memo 33 This Internet-Draft is submitted in full conformance with the 34 provisions of BCP 78 and BCP 79. 36 Internet-Drafts are working documents of the Internet Engineering 37 Task Force (IETF). Note that other groups may also distribute 38 working documents as Internet-Drafts. The list of current Internet- 39 Drafts is at http://datatracker.ietf.org/drafts/current/. 41 Internet-Drafts are draft documents valid for a maximum of six months 42 and may be updated, replaced, or obsoleted by other documents at any 43 time. It is inappropriate to use Internet-Drafts as reference 44 material or to cite them other than as "work in progress." 46 This Internet-Draft will expire on June 5, 2017. 48 Copyright Notice 50 Copyright (c) 2016 IETF Trust and the persons identified as the 51 document authors. All rights reserved. 53 This document is subject to BCP 78 and the IETF Trust's Legal 54 Provisions Relating to IETF Documents 55 (http://trustee.ietf.org/license-info) in effect on the date of 56 publication of this document. Please review these documents 57 carefully, as they describe your rights and restrictions with respect 58 to this document. Code Components extracted from this document must 59 include Simplified BSD License text as described in Section 4.e of 60 the Trust Legal Provisions and are provided without warranty as 61 described in the Simplified BSD License. 63 Table of Contents 65 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 66 2. BGP Large Communities Attribute . . . . . . . . . . . . . . . 3 67 3. Aggregation . . . . . . . . . . . . . . . . . . . . . . . . . 4 68 4. Canonical Representation . . . . . . . . . . . . . . . . . . 4 69 5. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 4 70 6. Security Considerations . . . . . . . . . . . . . . . . . . . 5 71 7. Implementation status - RFC EDITOR: REMOVE BEFORE PUBLICATION 5 72 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 73 9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6 74 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6 75 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 76 11.1. Normative References . . . . . . . . . . . . . . . . . . 7 77 11.2. Informative References . . . . . . . . . . . . . . . . . 7 78 11.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 8 79 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 81 1. Introduction 83 BGP [RFC4271] implementations typically support a routing policy 84 language to control the distribution of routing information. Network 85 operators attach BGP communities to routes to associate particular 86 properties with these routes. These properties may include 87 information such as the route origin location, or specification of a 88 routing policy action to be taken, or one that has been taken, and is 89 applied to all routes contained in a BGP Update Message where the 90 Communities Attribute is included. Because BGP communities are 91 optional transitive BGP attributes, BGP communities may be acted upon 92 or otherwise used by routing policies in other Autonomous Systems 93 (ASes) on the Internet. 95 BGP Communities attributes are a variable length attribute consisting 96 of a set of one or more four-octet values, each of which specify a 97 community [RFC1997]. Common use of the individual values of this 98 attribute type split this single 32-bit value into two 16-bit values. 99 The most significant word is interpreted as an Autonomous System 100 Number (ASN) and the least significant word is a locally defined 101 value whose meaning is assigned by the operator of the Autonomous 102 System in the most significant word. 104 Since the adoption of four-octet ASNs [RFC6793], the BGP Communities 105 attribute can no longer accommodate the above encoding, as a two- 106 octet word cannot fit a four-octet ASN. The BGP Extended Communities 107 attribute [RFC4360] is also unsuitable. The six-octet length of the 108 Extended Community value precludes the common operational practise of 109 encoding four-octet ASNs in both the Global Administrator and the 110 Local Administrator sub-fields. 112 To address these shortcomings, this document defines a BGP Large 113 Communities attribute encoded as an unordered set of one or more 114 twelve-octet values, each consisting of a four-octet Global 115 Administrator field and two four-octet operator-defined fields, each 116 of which can be used to denote properties or actions significant to 117 the operator of the Autonomous System assigning the values. 119 2. BGP Large Communities Attribute 121 This document defines the BGP Large Communities attribute as an 122 optional transitive path attribute of variable length. All routes 123 with the BGP Large Communities attribute belong to the communities 124 specified in the attribute. 126 Each BGP Large Community value is encoded as a 12-octet quantity, as 127 follows: 129 0 1 2 3 130 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 131 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 132 | Global Administrator | 133 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 134 | Local Data Part 1 | 135 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 136 | Local Data Part 2 | 137 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 139 Global Administrator: A four-octet namespace identifier. 141 Local Data Part 1: A four-octet operator-defined value. 143 Local Data Part 2: A four-octet operator-defined value. 145 The Global Administrator field is intended to allow different 146 Autonomous Systems to define BGP Large Communities without collision. 147 This field SHOULD be an Autonomous System Number (ASN). The use of 148 Reserved ASNs (0 [RFC7607], 65535 and 4294967295 [RFC7300]) is NOT 149 RECOMMENDED. 151 There is no significance to the order in which twelve-octet Large 152 Community Attribute values are encoded in a Large Communities 153 attribute, A BGP speaker can transmit them in any order. 155 Duplicate BGP Large Community values MUST NOT be transmitted. A 156 receiving speaker MUST silently remove redundant BGP Large Community 157 values from a BGP Large Community attribute. 159 3. Aggregation 161 If a range of routes is aggregated, then the resulting aggregate 162 should have a BGP Large Communities attribute which contains all of 163 the BGP Large Communities attributes from all of the aggregated 164 routes. 166 4. Canonical Representation 168 The canonical representation of BGP Large Communities is three 169 separate unsigned integers in decimal notation in the following 170 order: Global Administrator, Local Data 1, Local Data 2. Numbers 171 MUST NOT contain leading zeros; a zero value MUST be represented with 172 a single zero. Each number is separated from the next by a single 173 colon. For example: 64496:4294967295:2, 64496:0:0. 175 BGP Large Communities SHOULD be represented in the canonical 176 representation. 178 5. Error Handling 180 The error handling of BGP Large Communities is as follows: 182 o A BGP Large Communities attribute SHALL be considered malformed if 183 the length of the BGP Large Communities Attribute value, expressed 184 in octets, is not a non-zero multiple of 12. 186 o A BGP Large Communities attribute SHALL NOT be considered 187 malformed due solely to presence of duplicate community values. 189 o A BGP UPDATE message with a malformed BGP Large Communities 190 attribute SHALL be handled using the approach of "treat-as- 191 withdraw" as described in section 2 [RFC7606]. 193 The BGP Large Communities Global Administrator field may contain any 194 value, and a BGP Large Communities attribute MUST NOT be considered 195 malformed if the Global Administrator field contains an unallocated, 196 unassigned or reserved ASN. 198 6. Security Considerations 200 This extension to BGP has similar security implications as BGP 201 Communities [RFC1997]. 203 This document does not change any underlying security issues 204 associated with any other BGP Communities mechanism. Specifically, 205 an AS relying on the BGP Large Communities attribute carried in BGP 206 must have trust in every other AS in the path, as any intermediate 207 Autonomous System in the path may have added, deleted, or altered the 208 BGP Large Communities attribute. Specifying the mechanism to provide 209 such trust is beyond the scope of this document. 211 BGP Large Communities do not protect the integrity of each community 212 value. Operators should be aware that it is possible for a BGP 213 speaker to alter BGP Large Community Attribute values in a BGP Update 214 Message. Protecting the integrity of the transitive handling of BGP 215 Large Community attributes in a manner consistent with the intent of 216 expressed BGP routing policies falls within the broader scope of 217 securing BGP, and is not specifically addressed here. 219 Network administrators should note the recommendations in Section 11 220 of BGP Operations and Security [RFC7454]. 222 7. Implementation status - RFC EDITOR: REMOVE BEFORE PUBLICATION 224 This section records the status of known implementations of the 225 protocol defined by this specification at the time of posting of this 226 Internet-Draft, and is based on a proposal described in [RFC7942]. 227 The description of implementations in this section is intended to 228 assist the IETF in its decision processes in progressing drafts to 229 RFCs. Please note that the listing of any individual implementation 230 here does not imply endorsement by the IETF. Furthermore, no effort 231 has been spent to verify the information presented here that was 232 supplied by IETF contributors. This is not intended as, and must not 233 be construed to be, a catalog of available implementations or their 234 features. Readers are advised to note that other implementations may 235 exist. 237 As of today these vendors have produced an implementation of BGP 238 Large Communities: 240 o Cisco IOS XR 242 o ExaBGP 244 o GoBGP 246 o BIRD 248 o OpenBGPD 250 o pmacct 252 o Quagga 254 The latest implementation news is tracked at 255 http://largebgpcommunities.net/ [1]. 257 8. IANA Considerations 259 IANA has made an Early Allocation of the value 32 (LARGE_COMMUNITY) 260 in the "BGP Path Attributes" registry under the "Border Gateway 261 Protocol (BGP) Parameters" group and is now asked to make that 262 Permanent. 264 9. Contributors 266 The following people contributed significantly to the content of the 267 document: 269 John Heasley 270 NTT Communications 271 Email: heas@shrubbery.net 273 Adam Simpson 274 Nokia 275 Email: adam.1.simpson@nokia.com 277 10. Acknowledgments 279 The authors would like to thank Ruediger Volk, Russ White, Acee 280 Lindem, Shyam Sethuram, Jared Mauch, Joel M. Halpern, Jeffrey Haas, 281 Gunter van de Velde, Marco Marzetti, Eduardo Ascenco Reis, Mark 282 Schouten, Paul Hoogsteder, Martijn Schmidt, Greg Hankins, Bertrand 283 Duvivier, Barry O'Donovan, Grzegorz Janoszka, Linda Dunbar, Marco 284 Davids, Gaurab Raj Upadhaya, Jeff Tantsura, Teun Vink, Adam 285 Davenport, Theodore Baschak, Pier Carlo Chiodi, Nabeel Cocker, Ian 286 Dickinson, Jan Baggen, Duncan Lockwood, David Farmer, Randy Bush, Wim 287 Henderickx, Stefan Plug, Kay Rechthien, Rob Shakir, Warren Kumari, 288 Gert Doering, Thomas King, Mikael Abrahamsson, Wesley Steehouwer, 289 Sander Steffann, Brad Dreisbach, Martin Millnert, Christopher Morrow, 290 Jay Borkenhagen, Arnold Nipper, Joe Provo, Niels Bakker, Bill Fenner, 291 Tom Daly, Ben Maddison, Alexander Azimov, Brian Dickson, Peter van 292 Dijk, Julian Seifert, Tom Petch, Tom Scholl, Arjen Zonneveld, Remco 293 van Mook, Adam Chappell, Jussi Peltola, Kristian Larsson, Markus 294 Hauschild, Richard Steenbergen, David Freedman, Richard Hartmann, 295 Geoff Huston, Mach Chen, and Alvaro Retana for their support, 296 insightful review and comments. 298 11. References 300 11.1. Normative References 302 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 303 Requirement Levels", BCP 14, RFC 2119, 304 DOI 10.17487/RFC2119, March 1997, 305 . 307 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 308 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 309 DOI 10.17487/RFC4271, January 2006, 310 . 312 [RFC7606] Chen, E., Ed., Scudder, J., Ed., Mohapatra, P., and K. 313 Patel, "Revised Error Handling for BGP UPDATE Messages", 314 RFC 7606, DOI 10.17487/RFC7606, August 2015, 315 . 317 11.2. Informative References 319 [RFC1997] Chandra, R., Traina, P., and T. Li, "BGP Communities 320 Attribute", RFC 1997, DOI 10.17487/RFC1997, August 1996, 321 . 323 [RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended 324 Communities Attribute", RFC 4360, DOI 10.17487/RFC4360, 325 February 2006, . 327 [RFC6793] Vohra, Q. and E. Chen, "BGP Support for Four-Octet 328 Autonomous System (AS) Number Space", RFC 6793, 329 DOI 10.17487/RFC6793, December 2012, 330 . 332 [RFC7300] Haas, J. and J. Mitchell, "Reservation of Last Autonomous 333 System (AS) Numbers", BCP 6, RFC 7300, 334 DOI 10.17487/RFC7300, July 2014, 335 . 337 [RFC7454] Durand, J., Pepelnjak, I., and G. Doering, "BGP Operations 338 and Security", BCP 194, RFC 7454, DOI 10.17487/RFC7454, 339 February 2015, . 341 [RFC7607] Kumari, W., Bush, R., Schiller, H., and K. Patel, 342 "Codification of AS 0 Processing", RFC 7607, 343 DOI 10.17487/RFC7607, August 2015, 344 . 346 [RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running 347 Code: The Implementation Status Section", BCP 205, 348 RFC 7942, DOI 10.17487/RFC7942, July 2016, 349 . 351 11.3. URIs 353 [1] http://largebgpcommunities.net 355 Authors' Addresses 357 Jakob Heitz (editor) 358 Cisco 359 170 West Tasman Drive 360 San Jose, CA 95054 361 USA 363 Email: jheitz@cisco.com 365 Job Snijders (editor) 366 NTT Communications 367 Theodorus Majofskistraat 100 368 Amsterdam 1065 SZ 369 The Netherlands 371 Email: job@ntt.net 373 Keyur Patel 374 Arrcus, Inc 376 Email: keyur@arrcus.com 377 Ignas Bagdonas 378 Equinix 379 80 Cheapside 380 London EC2V 6EE 381 United Kingdom 383 Email: ibagdona.ietf@gmail.com 385 Nick Hilliard 386 INEX 387 4027 Kingswood Road 388 Dublin 24 389 IE 391 Email: nick@inex.ie