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Please use uppercase 'NOT' together with RFC 2119 keywords (if that is what you mean). Found 'SHOULD not' in this paragraph: This document introduces a new AFI known as a "BGP Opaque Data AFI", with the actual code-point value to be assigned by IANA. The purpose of this AFI is to exchange opaque information within a BGP network. The propagation scope of the opaque data is to be controlled by the usual means of BGP policy, except that the policy SHOULD not match on NLRI information in any form other than an opaque string. -- The document date (October 30, 2017) is 2363 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-36) exists of draft-ietf-idr-bgp-extended-messages-22 -- Obsolete informational reference (is this intentional?): RFC 5575 (Obsoleted by RFC 8955) -- Obsolete informational reference (is this intentional?): RFC 7752 (Obsoleted by RFC 9552) Summary: 0 errors (**), 0 flaws (~~), 3 warnings (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Inter-Domain Routing P. Lapukhov 3 Internet-Draft Facebook 4 Intended status: Standards Track E. Aries, Ed. 5 Expires: May 3, 2018 P. Marques 6 Juniper Networks 7 E. Nkposong 8 Salesforce.com Inc 9 October 30, 2017 11 Use of BGP for Opaque Signaling 12 draft-lapukhov-bgp-opaque-signaling-04 14 Abstract 16 Border Gateway Protocol with multi-protocol extensions (MP-BGP) 17 enables the use of the protocol for dissemination of virtually any 18 information. This document proposes a new Address Family/Subsequent 19 Address Family to be used for distribution of opaque data. This 20 functionality is intended to be used by applications other than BGP 21 for exchange of their own data on top of BGP mesh. The structure of 22 such data SHOULD NOT be interpreted by the regular BGP speakers, 23 rather the goal is to use BGP purely as a convenient and scalable 24 communication system. 26 Requirements Language 28 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 29 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 30 document are to be interpreted as described in RFC 2119 [RFC2119]. 32 Status of This Memo 34 This Internet-Draft is submitted in full conformance with the 35 provisions of BCP 78 and BCP 79. 37 Internet-Drafts are working documents of the Internet Engineering 38 Task Force (IETF). Note that other groups may also distribute 39 working documents as Internet-Drafts. The list of current Internet- 40 Drafts is at https://datatracker.ietf.org/drafts/current/. 42 Internet-Drafts are draft documents valid for a maximum of six months 43 and may be updated, replaced, or obsoleted by other documents at any 44 time. It is inappropriate to use Internet-Drafts as reference 45 material or to cite them other than as "work in progress." 47 This Internet-Draft will expire on May 3, 2018. 49 Copyright Notice 51 Copyright (c) 2017 IETF Trust and the persons identified as the 52 document authors. All rights reserved. 54 This document is subject to BCP 78 and the IETF Trust's Legal 55 Provisions Relating to IETF Documents 56 (https://trustee.ietf.org/license-info) in effect on the date of 57 publication of this document. Please review these documents 58 carefully, as they describe your rights and restrictions with respect 59 to this document. Code Components extracted from this document must 60 include Simplified BSD License text as described in Section 4.e of 61 the Trust Legal Provisions and are provided without warranty as 62 described in the Simplified BSD License. 64 Table of Contents 66 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 67 2. BGP Opaque Data AFI . . . . . . . . . . . . . . . . . . . . . 3 68 3. BGP Key-Value SAFI . . . . . . . . . . . . . . . . . . . . . 3 69 4. BGP VPN Key-Value SAFI . . . . . . . . . . . . . . . . . . . 3 70 5. Capability Advertisement . . . . . . . . . . . . . . . . . . 3 71 6. Disseminating Key-Value associations . . . . . . . . . . . . 3 72 6.1. Publishing a Key-Value binding . . . . . . . . . . . . . 4 73 6.2. Removing a Key-Value binding . . . . . . . . . . . . . . 5 74 7. Manageability Considerations . . . . . . . . . . . . . . . . 6 75 7.1. Propagating multiple values for the same key . . . . . . 6 76 7.2. Automatic filtering . . . . . . . . . . . . . . . . . . . 6 77 7.3. Filtering via policy . . . . . . . . . . . . . . . . . . 6 78 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 79 9. Security Considerations . . . . . . . . . . . . . . . . . . . 7 80 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7 81 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 82 11.1. Normative References . . . . . . . . . . . . . . . . . . 7 83 11.2. Informative References . . . . . . . . . . . . . . . . . 7 84 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 86 1. Introduction 88 Implementation of Multiprotocol Extensions for BGP-4 [RFC4760] gives 89 the ability to pass arbitrary data in BGP protocol messages. This 90 capability has been leveraged by many for dissemination of non- 91 routing related information over BGP (e.g. "Dissemination of Flow 92 Specification Rules" [RFC5575] as well as "North-Bound Distribution 93 of Link-State and TE Information using BGP" [RFC7752]). However, 94 there has been no channel defined explicitly to disseminate data with 95 arbitrary payload. The intended use case is for applications other 96 than BGP to leverage the protocol machinery for distribution 97 (broadcasting) of their own state in the network domain. Publishers 98 and consumers will use BGP UPDATE messages over TCP transport to 99 submit and receive opaque data. It is up to the BGP implementation 100 to provide a custom API for message producers or consumers, if 101 needed. 103 2. BGP Opaque Data AFI 105 This document introduces a new AFI known as a "BGP Opaque Data AFI", 106 with the actual code-point value to be assigned by IANA. The purpose 107 of this AFI is to exchange opaque information within a BGP network. 108 The propagation scope of the opaque data is to be controlled by the 109 usual means of BGP policy, except that the policy SHOULD not match on 110 NLRI information in any form other than an opaque string. 112 3. BGP Key-Value SAFI 114 This document introduces a new SAFI known as "BGP Key-Value SAFI" 115 with the actual code-point value to be assigned by IANA. The purpose 116 of this SAFI is exchange of opaque information structured as Key- 117 Value associations. 119 4. BGP VPN Key-Value SAFI 121 This document introduces a new SAFI known as a "BGP VPN Key-Value 122 SAFI" with the actual code-point value to be assigned by IANA. The 123 purpose of this SAFI is exchange of opaque information structured as 124 a Key-Value association within a Virtual Private Network provided as 125 a service. The [RFC4364] defines a method and procedures for 126 implementing VPNs using BGP as a control plane. All the procedures 127 of [RFC4364] apply to the BGP VPN Key-Value SAFI. Under this SAFI, 128 the NLRI for the opaque information has the mandatory 8 bytes of 129 Route Distinguisher at the beginning of the NLRI field. 131 5. Capability Advertisement 133 A BGP speaker that wishes to exchange Opaque Data MUST use the 134 Multiprotocol Extensions Capability Code, as defined in [RFC4760], to 135 advertise the corresponding AFI/SAFI pair. 137 6. Disseminating Key-Value associations 139 This document proposes a distributed, eventually consistent Key-Value 140 store on top of existing BGP protocol transport mechanism. The "Key" 141 and "Value" portions are to be encoded within the NLRI part of 142 MP_REACH_NLRI attribute. 144 o Publishers advertise keys along with associated values into the 145 routing domain. The BGP network disseminates that state by 146 propagating the encoded data following the usual BGP protocol 147 operations. 149 o Consumers receive the information via BGP protocol UPDATE 150 messages, active as passively listening BGP speakers. Only 151 publishers and consumers of the opaque data are supposed to 152 interpret its contents. The rest of the BGP network acts merely 153 as a dissemination system. 155 Multiple publishers can advertise the same key bound to different 156 values. Only the "Key" part of MP_REACH_NLRI filed MUST be used to 157 differentiate unique advertisements in such case. It is also 158 possible for the advertised associations to have the same Key-Value 159 pairs, but differ in some other BGP attributes. In that case, the 160 BGP implementation MUST follow the regular best-path selection logic 161 to prevent duplicate information in the network. A consumer will 162 receive the value created by the publisher "closest" in terms of BGP 163 best-path selection logic, based on the policies that exist in the 164 routing domain. 166 6.1. Publishing a Key-Value binding 168 The encoding scheme proposed below follows the semantics of a Key- 169 Value association. The "Key" and "Value" are stored in the NLRI 170 section of the MP_REACH_NLRI attribute, as illustrated on Figure 1. 172 +---------------------------------------------------------+ 173 | Address Family Identifier (2 octets) | 174 +---------------------------------------------------------+ 175 | Subsequent Address Family Identifier (1 octet) | 176 +---------------------------------------------------------+ 177 | Length of Next Hop Address (1 octet), must be zero | 178 +---------------------------------------------------------+ 179 | Reserved (1 octet), must be zero | 180 +---------------------------------------------------------+ 181 | Opaque Key Length (2 octets) | 182 +---------------------------------------------------------+ 183 | Opaque Key Data (variable) | 184 +---------------------------------------------------------+ 185 | Opaque Value Data (variable) | 186 +---------------------------------------------------------+ 188 Figure 1: MP_REACH_NLRI Layout 190 o The AFI/SAFI values are to be allocated by IANA. 192 o Length of Next Hop Address: must be zero, indicating empty next- 193 hop. 195 o Opaque Key Length: identifies the size of the Key field in octets, 196 an unsigned integer value. The field MUST have a value of at 197 least one octet under the Key-Value SAFI and at least 9 octets 198 under the VPN Key-Value SAFI. Violating this requirement MUST 199 cause the receiver to ignore the advertised Key-Value association. 201 o Opaque Key Data: the byte string representing the opaque key 202 contents. 204 o Opaque Value Data: The length of this field is determined by 205 subtracting the length of all previous fields from the total 206 length of MP_REACH_NLRI attribute. This field MAY be empty. 208 The maximum size of the Opaque "Key" and "Value" fields together is 209 limited by the BGP UPDATE message size. With the default BGP 210 protocol implementation the mssage may not exceed 4096 octets (see 211 [RFC4271] Section 4). However, if 212 [I-D.ietf-idr-bgp-extended-messages] is implemented, the UPDATE 213 message size could be as large as 65536 octets. 215 6.2. Removing a Key-Value binding 217 The removal procedure follows the regular MP-BGP route withdrawal, 218 using the MP_UNREACH_NLRI attribute. This section defines the 219 attribute structure for the new AFI/SAFI. 221 The specific MP_UNREACH_NLRI format is shown on Figure 2. This 222 message instructs the receiving BGP speaker to delete the N 223 associations corresponding to Key 1, Key 2 ... Key N if the keys have 224 been previously learned from the withdrawing speaker. If any of the 225 keys could not be found in the LocRIB or the keys have not been 226 previously received from the withdrawing BGP peer, such key removal 227 request MUST be ignored and the event MAY be logged. For the Key- 228 Value SAFI, each "Key Length" field must have the value of at least 229 "1". For the VPN Key-Value SAFI, each "Key Length" must be at least 230 9 octets long. Violation of of these constraints MUST cause the 231 receiver of the UPDATE message to ignore the corresponding key 232 withdrawal. 234 +---------------------------------------------------------+ 235 | Address Family Identifier (2 octets) | 236 +---------------------------------------------------------+ 237 | Subsequent Address Family Identifier (1 octet) | 238 +---------------------------------------------------------+ 239 | Opaque Key 1 Length (1 octet) | 240 +---------------------------------------------------------+ 241 | Opaque Key 1 Data (variable) | 242 +---------------------------------------------------------+ 243 ~ ~ 244 | Opaque Key N Length (1 octet) | 245 +---------------------------------------------------------+ 246 | Opaque Key N Data (variable) | 247 +---------------------------------------------------------+ 249 Figure 2: MP_UNREACH_NLRI attribute layout 251 7. Manageability Considerations 253 7.1. Propagating multiple values for the same key 255 It is possible to propagate multiple values associated with the same 256 key using the Add-Path extension defined in [RFC7911]. However, this 257 document recommends that instead unique key values SHOULD be used for 258 this purpose. It is up to the consumers and publishers of the opaque 259 data to settle on single unique value using some kind of consensus 260 protocol. 262 As a recommendation, the originators of key-value pairs may use the 263 origin ASN and the IPv4 or IPv6 address assigned to the originating 264 BGP speaker to create a unique key prefix. Alternatively, UUIDs 265 could be used to generate the unique key names, see [RFC4122] 267 7.2. Automatic filtering 269 It is possible to leverage mechanics described in [RFC4684] and use 270 the route-target extended community attribute to identify "channels" 271 where Key-Value associations are published. The consumers would 272 signal their interest in particular "channel" by advertising the 273 corresponding router-target membership. The publications then need 274 to carry the router-target extended community attribute to restrict 275 information propagation scope. 277 7.3. Filtering via policy 279 Ad-doc message filtering could be implemented using BGP standard (see 280 [RFC4271]) or extended community attributes (see [RFC4360]). The 281 semantic of these attributes is to determined by the policy and 282 publishers/consumers. Filtering could be done locally on receiving 283 BGP speaker, or on remote BGP speaker, by using outbound route 284 filtering feature defined in [RFC5291]. 286 8. IANA Considerations 288 For the purpose of this work, IANA would be asked to allocate values 289 for the new AFI and SAFIs. 291 9. Security Considerations 293 This document does not introduce any changes in terms of BGP 294 security. The usual set of issues that arise from running multiple 295 AFI/SAFI's over single BGP session would apply in this case. 296 Additional concerns may be raised due to increase of the volume and 297 rate of change of the information distributed by means of opaque 298 signaling. 300 10. Acknowledgements 302 Keyur Patel provided useful feedback and suggested a practical 303 implementation of unique key semantic and support for VPN Key-Value 304 SAFI. 306 11. References 308 11.1. Normative References 310 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 311 Requirement Levels", BCP 14, RFC 2119, 312 DOI 10.17487/RFC2119, March 1997, 313 . 315 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 316 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 317 DOI 10.17487/RFC4271, January 2006, 318 . 320 11.2. Informative References 322 [I-D.ietf-idr-bgp-extended-messages] 323 Bush, R., Patel, K., and D. Ward, "Extended Message 324 support for BGP", draft-ietf-idr-bgp-extended-messages-22 325 (work in progress), August 2017. 327 [RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally 328 Unique IDentifier (UUID) URN Namespace", RFC 4122, 329 DOI 10.17487/RFC4122, July 2005, 330 . 332 [RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended 333 Communities Attribute", RFC 4360, DOI 10.17487/RFC4360, 334 February 2006, . 336 [RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private 337 Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February 338 2006, . 340 [RFC4684] Marques, P., Bonica, R., Fang, L., Martini, L., Raszuk, 341 R., Patel, K., and J. Guichard, "Constrained Route 342 Distribution for Border Gateway Protocol/MultiProtocol 343 Label Switching (BGP/MPLS) Internet Protocol (IP) Virtual 344 Private Networks (VPNs)", RFC 4684, DOI 10.17487/RFC4684, 345 November 2006, . 347 [RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter, 348 "Multiprotocol Extensions for BGP-4", RFC 4760, 349 DOI 10.17487/RFC4760, January 2007, 350 . 352 [RFC5291] Chen, E. and Y. Rekhter, "Outbound Route Filtering 353 Capability for BGP-4", RFC 5291, DOI 10.17487/RFC5291, 354 August 2008, . 356 [RFC5575] Marques, P., Sheth, N., Raszuk, R., Greene, B., Mauch, J., 357 and D. McPherson, "Dissemination of Flow Specification 358 Rules", RFC 5575, DOI 10.17487/RFC5575, August 2009, 359 . 361 [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and 362 S. Ray, "North-Bound Distribution of Link-State and 363 Traffic Engineering (TE) Information Using BGP", RFC 7752, 364 DOI 10.17487/RFC7752, March 2016, 365 . 367 [RFC7911] Walton, D., Retana, A., Chen, E., and J. Scudder, 368 "Advertisement of Multiple Paths in BGP", RFC 7911, 369 DOI 10.17487/RFC7911, July 2016, 370 . 372 Authors' Addresses 374 Petr Lapukhov 375 Facebook 376 1 Hacker Way 377 Menlo Park, CA 94025 378 US 380 Email: petr@fb.com 382 Ebben Aries (editor) 383 Juniper Networks 384 1133 Innovation Way 385 Sunnyvale, CA 94089 386 US 388 Email: exa@juniper.net 390 Pedro Marques 391 Juniper Networks 392 1194 N. Mathilda Ave 393 Sunnyvale, CA 94089 394 US 396 Email: roque@juniper.net 398 Edet Nkposong 399 Salesforce.com Inc 400 The Landmark @ One Market, ST 300 401 San Francisco, CA 94105 402 US 404 Email: enkposong@salesforce.com