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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group E. Chen 3 Internet Draft Cisco Systems 4 Expiration Date: January 2009 Y. Rekhter 5 Juniper Networks 7 Outbound Route Filtering Capability for BGP-4 9 draft-ietf-idr-route-filter-17.txt 11 Status of this Memo 13 By submitting this Internet-Draft, each author represents that any 14 applicable patent or other IPR claims of which he or she is aware 15 have been or will be disclosed, and any of which he or she becomes 16 aware will be disclosed, in accordance with Section 6 of BCP 79. 18 Internet-Drafts are working documents of the Internet Engineering 19 Task Force (IETF), its areas, and its working groups. Note that 20 other groups may also distribute working documents as Internet- 21 Drafts. 23 Internet-Drafts are draft documents valid for a maximum of six months 24 and may be updated, replaced, or obsoleted by other documents at any 25 time. It is inappropriate to use Internet-Drafts as reference 26 material or to cite them other than as "work in progress". 28 The list of current Internet-Drafts can be accessed at 29 http://www.ietf.org/ietf/1id-abstracts.txt 31 The list of Internet-Draft Shadow Directories can be accessed at 32 http://www.ietf.org/shadow.html. 34 Abstract 36 This document defines a BGP-based mechanism that allows a BGP speaker 37 to send to its BGP peer a set of Outbound Route Filters (ORFs) that 38 the peer would use to constrain/filter its outbound routing updates 39 to the speaker. 41 1. Specification of Requirements 43 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 44 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 45 document are to be interpreted as described in RFC 2119 [RFC-2119]. 47 2. Introduction 49 Currently it is not uncommon for a BGP speaker [BGP-4] to receive, 50 and then filter out some unwanted routes from its peers based on its 51 local routing policy. Since the generation and transmission of 52 routing updates by the sender, as well as the processing of routing 53 updates by the receiver consume resources, it may be beneficial if 54 the generation of such unwanted routing updates can be avoided in the 55 first place. 57 This document defines a BGP-based mechanism that allows a BGP speaker 58 to send to its BGP peer a set of Outbound Route Filters (ORFs). The 59 peer would then apply these filters, in addition to its locally 60 configured outbound filters (if any), to constrain/filter its 61 outbound routing updates to the speaker. 63 3. Outbound Route Filter (ORF) 65 This document uses the terms "Address Family Identifier (AFI)" and 66 "Subsequent Address Family Identifier (SAFI)". In the context of this 67 document the meaning of these terms is the same as in [BGP-MP]. 69 Conceptually an ORF entry is a tuple of the form ; an ORF consists of one or more ORF entries 71 that have a common AFI/SAFI and ORF-Type. An ORF is identified by 72 . 74 The "AFI/SAFI" component provides a coarse granularity control by 75 limiting the ORF to only the routes whose NLRI matches the "AFI/SAFI" 76 component of the ORF. 78 The "ORF-Type" component determines the content of the ORF-value. 80 The "Action" component controls handling of the ORF Request by the 81 remote peer. Action can be one of ADD, REMOVE, REMOVE-ALL. ADD adds 82 an ORF entry to the ORF on the remote peer; REMOVE deletes a 83 previously installed ORF entry on the remote peer; REMOVE-ALL deletes 84 the previously installed entries in the specified ORF on the remote 85 peer. 87 The "Match" component is used to support matching granularity on a 88 per ORF entry basis. It can be either PERMIT or DENY. The semantics 89 of PERMIT is to ask the peer to pass updates for the set of routes 90 that match the ORF entry. The semantics of DENY is to ask the peer 91 not to pass updates for the set of routes that match the ORF entry. 93 When an ORF is defined, an ORF specific matching rule MUST be 94 specified so that there is no ambiguity regarding which ORF entry is 95 considered as the matching entry in the ORF when a route is passed 96 through the ORF. 98 4. Carrying ORF Entries in BGP 100 ORF entries are carried in the BGP ROUTE-REFRESH message [BGP-RR]. 102 A BGP speaker can distinguish an incoming ROUTE-REFRESH message that 103 carries one or more ORF entries from an incoming plain ROUTE-REFRESH 104 message by using the Message Length field in the BGP message header. 106 A single ROUTE-REFRESH message MAY carry multiple ORF entries in one 107 or more ORFs, as long as all these entries share the same AFI/SAFI. 109 From the encoding point of view each ORF entry consists of a common 110 part and type-specific part as shown in Figure 1 and Figure 2. 112 The common part consists of , and 113 is encoded as follows: 115 The AFI/SAFI component of an ORF entry is encoded in the AFI/SAFI 116 field of the ROUTE-REFRESH message. 118 Following the AFI/SAFI component is the one-octet When-to-refresh 119 field. The value of this field can be either IMMEDIATE (0x01) or 120 DEFER (0x02). The semantics of IMMEDIATE and DEFER are discussed 121 in the "Operation" section of this document. 123 Following the When-to-refresh field is a collection of one or more 124 ORFs, grouped by ORF-Type. 126 The ORF-Type component is encoded as a one-octet field. 128 The "Length of ORF entries" component is a two-octet field that 129 contains the total length (in octets) of the ORF entries that 130 follows for the specified ORF type. 132 +--------------------------------------------------+ 133 | Address Family Identifier (2 octets) | 134 +--------------------------------------------------+ 135 | Reserved (1 octet) | 136 +--------------------------------------------------+ 137 | Subsequent Address Family Identifier (1 octet) | 138 +--------------------------------------------------+ 139 | When-to-refresh (1 octet) | 140 +--------------------------------------------------+ 141 | ORF Type (1 octet) | 142 +--------------------------------------------------+ 143 | Length of ORF entries (2 octets) | 144 +--------------------------------------------------+ 145 | First ORF entry (variable) | 146 +--------------------------------------------------+ 147 | Second ORF entry (variable) | 148 +--------------------------------------------------+ 149 | ... | 150 +--------------------------------------------------+ 151 | N-th ORF entry (variable) | 152 +--------------------------------------------------+ 153 | ORF Type (1 octet) | 154 +--------------------------------------------------+ 155 | Length of ORF entries (2 octets) | 156 +--------------------------------------------------+ 157 | First ORF entry (variable) | 158 +--------------------------------------------------+ 159 | Second ORF entry (variable) | 160 +--------------------------------------------------+ 161 | ... | 162 +--------------------------------------------------+ 163 | N-th ORF entry (variable) | 164 +--------------------------------------------------+ 165 | ... | 166 +--------------------------------------------------+ 168 Figure 1: Carrying ORF Entries in the ROUTE-REFRESH Message 170 The rest of the components in the common part are encoded in the 171 first octet of each ORF-entry (from the most significant to the least 172 significant bit) as shown in Figure 2: 174 Action is a two-bit field. The value of this field is 0 for ADD, 1 175 for REMOVE, and 2 for REMOVE-ALL. 177 Match is a one-bit field. The value of this field is 0 for PERMIT 178 and 1 for DENY. This field is significant only when the value of 179 the Action field is either ADD or REMOVE. 181 Reserved is a 5-bit field. It is set to 0 on transmit and ignored 182 on receive. 184 +---------------------------------+ 185 | Action (2 bit) | 186 +---------------------------------+ 187 | Match (1 bit) | 188 +---------------------------------+ 189 | Reserved (5 bits) | 190 +---------------------------------+ 191 | Type specific part (variable) | 192 +---------------------------------+ 194 Figure 2: ORF Entry Encoding 196 When the Action component of an ORF entry specifies REMOVE-ALL, 197 the entry consists of only the common part. 199 5. Outbound Route Filtering Capability 201 A BGP speaker that is willing to receive ORF entries from its peer, 202 or a BGP speaker that would like to send ORF entries to its peer, 203 advertises this to the peer by using the Outbound Route Filtering 204 Capability, as described below. 206 The Outbound Route Filtering Capability is a new BGP capability 207 [BGP-CAP] defined as follows: 209 Capability code: 3 211 Capability length: variable 213 Capability value: one or more of the entries as shown in Figure 3. 215 +--------------------------------------------------+ 216 | Address Family Identifier (2 octets) | 217 +--------------------------------------------------+ 218 | Reserved (1 octet) | 219 +--------------------------------------------------+ 220 | Subsequent Address Family Identifier (1 octet) | 221 +--------------------------------------------------+ 222 | Number of ORFs (1 octet) | 223 +--------------------------------------------------+ 224 | ORF Type (1 octet) | 225 +--------------------------------------------------+ 226 | Send/Receive (1 octet) | 227 +--------------------------------------------------+ 228 | ... | 229 +--------------------------------------------------+ 230 | ORF Type (1 octet) | 231 +--------------------------------------------------+ 232 | Send/Receive (1 octet) | 233 +--------------------------------------------------+ 235 Figure 3: Outbound Route Filtering Capability Encoding 237 The use and meaning of these fields are as follows: 239 Address Family Identifier (AFI): 241 This field is the same as the one used in [BGP-MP]. 243 Subsequent Address Family Identifier (SAFI): 245 This field is the same as the one used in [BGP-MP]. 247 Number of ORF Types: 249 This field contains the number of Filter Types to be listed in 250 the following fields. 252 ORF Type: 254 This field contains the value of an ORF Type. 256 Send/Receive: 258 This field indicates whether the sender is (a) willing to 259 receive ORF entries from its peer (value 1), (b) would like to 260 send ORF entries to its peer (value 2), or (c) both (value 3) 261 for the ORF Type. 263 6. Operation 265 A BGP speaker that is willing to receive ORF entries from its peer, 266 or would like to send ORF entries to its peer SHOULD advertise the 267 Outbound Route Filtering Capability to the peer using BGP 268 Capabilities advertisement [BGP-CAP]. 270 A BGP speaker that implements the Outbound Route Filtering Capability 271 MUST support the BGP ROUTE-REFRESH message, as defined in [BGP-RR]. A 272 BGP speaker that advertises the Outbound Route Filtering Capability 273 to a peer using BGP Capabilities advertisement [BGP-CAP] does not 274 have to advertise the BGP Route Refresh capability to that peer. 276 Consider a BGP speaker that advertises the Outbound Route Filtering 277 Capability indicating its willingness to receive a particular set of 278 from its peer, and that receives the Outbound 279 Route Filtering Capability indicating the desire of the peer to send 280 a particular set to the speaker. If for a given 281 AFI/SAFI the intersection between these two sets is not-empty, the 282 speaker SHOULD NOT advertise to the peer any routes with that 283 AFI/SAFI prior to receiving from the peer any ROUTE-REFRESH message 284 carrying that AFI/SAFI, where the message could be either without any 285 ORF entries, or with one or more ORF entry and When-to-refresh field 286 set to IMMEDIATE. If, on the other hand, for a given AFI/SAFI the 287 intersection between these two sets is empty, the speaker MUST follow 288 normal BGP procedures. 290 A BGP speaker may send a ROUTE-REFRESH message with one or more ORF 291 entries to its peer only if the peer advertises to the speaker the 292 Outbound Route Filtering Capability indicating its willingness to 293 receive ORF entries from the speaker, and the speaker advertises to 294 the peer the Outbound Route Filtering Capability indicating its 295 desire to send ORF entries to the peer. The message may contain only 296 ORF entries of that the peer is willing to 297 receive, as advertised to the speaker in the Outbound Route Filtering 298 Capability. 300 When a BGP speaker receives a ROUTE-REFRESH message with one or more 301 ORF entries from its peer, then the speaker performs the following 302 actions. If an carried by the message does not 303 match that the speaker is willing to receive 304 from the peer (as advertised to the peer in the Outbound Route 305 Filtering Capability), the specified ORF entries in the message are 306 ignored. Otherwise, the speaker modifies the specified ORF 307 previously received, according to the ORF entries carried in the 308 message. If any of the fields of an ORF entry in the message contains 309 an unrecognized value, the whole specified ORF previously received is 310 removed. 312 If the Action component of an ORF entry is REMOVE, but the ORF 313 previously received does not contain the specified entry, the ORF 314 entry in the message is ignored. 316 ORF entries with either REMOVE or REMOVE-ALL can not remove locally 317 configured outbound route filters. 319 If the When-to-refresh indicates IMMEDIATE, then after processing all 320 the ORF entries carried in the message the speaker re-advertises to 321 the peer routes from the Adj-RIB-Out associated with the peer that 322 have the same AFI/SAFI as what is carried in the message, and taking 323 into account all the ORF entries for that AFI/SAFI received from the 324 peer. The speaker MUST re-advertise all the routes that have been 325 affected by the ORF entries carried in the message, but MAY also re- 326 advertise the routes that have not been affected by the ORF entries 327 carried in the message. 329 If the When-to-refresh indicates DEFER, then after processing all the 330 ORF entries carried in the message the speaker defers re- 331 advertisement to the peer routes from the Adj-RIB-Out associated with 332 the peer that have the same AFI/SAFI as what is carried in the 333 message, and taking into account all the ORF entries received from 334 the peer until the speaker receives a subsequent ROUTE-REFRESH 335 message for the same AFI/SAFI either without any ORF entries, or with 336 one or more ORF entries and When-to-refresh set to IMMEDIATE. 338 If the speaker receives from the peer a ROUTE-REFRESH message without 339 any ORF entries, then the speaker sends to the peer all routes from 340 the Adj-RIB-Out associated with the peer whose AFI/SAFI is the same 341 as what is carried in the message and taking into account the ORFs 342 (if any) previously received from the peer. 344 The set of ORF entries that the speaker sends to the peer expresses 345 the speaker's local preference, that the peer may or may not decide 346 to honor. 348 During a single BGP session the speaker MAY pass multiple ORF entries 349 to the peer. 351 After a BGP speaker makes changes to the ORF entries previously sent 352 to a peer, the speaker MUST send to the peer the updated ORF entries 353 with either (a) When-to-refresh set to IMMEDIATE, or (b) When-to- 354 refresh set to DEFER followed by a plain ROUTE-REFRESH message. The 355 latter MUST be used by the speaker when there are other policy 356 changes (in addition to the ORF entries) that require the peer to 357 re-advertise all the routes. 359 The lifetime of an ORF is the duration of the BGP session during 360 which the ORF is exchanged. 362 An ORF is removed when the last ORF entry is removed (either via 363 REMOVE-ALL, or via a sequence of REMOVE). 365 If a particular route maintained by a BGP speaker does not match any 366 of the ORF entries of any of the (non-empty) ORFs associated with a 367 particular peer, then this route SHOULD NOT be advertised to the 368 peer. 370 If a BGP speaker maintains multiple ORFs of different ORF-Types for a 371 particular peer, then the decision by the speaker to advertise a 372 route to the peer is determined by passing the route through each 373 such ORF, and and-ing the results (and-ing of PERMIT and DENY results 374 in DENY). 376 7. IANA Considerations 378 This document defines a new BGP Capability - Outbound Route Filtering 379 Capability. The Capability Code for the Outbound Route Filtering 380 Capability is 3. 382 As specified in this document, an ORF entry contains the ORF-Type 383 field for which IANA is to create and maintain a registry entitled 384 "BGP ORF Type". 386 IANA will maintain and register values for ORF-Type field as follows: 388 - ORF-Type value 0 is reserved. 390 - ORF-Type values 1 through 63 are to be assigned by IANA using 391 either the Standards Action process defined in RFC 2434, or the 392 Early IANA Allocation process defined in RFC 4020. 394 - ORF-Type values 64 through 127 are to be assigned by IANA, using 395 the "First Come First Served" policy defined in RFC 2434. 397 - ORF-Type values 128 through 255 are vendor-specific, and values 398 in this range are not to be assigned by IANA. 400 8. Manageability Considerations 402 The management objects for BGP ORFs will be defined separately, 403 outside this document. However, it is suggested that the following 404 management objects be defined: 406 The ORF capability object, which describes the ORF capability 407 exchanged over a BGP session, should include the ORF types and the 408 Send/Receive values advertised and received for a BGP peer. 410 The ORF entry object should contain the ORF entries of each ORF sent 411 and received for a BGP peer. 413 9. Security Considerations 415 This extension to BGP does not change the underlying security issues 416 [BGP-4]. 418 10. Intellectual Property Considerations 420 This section is taken from Section 5 of RFC 3668. 422 The IETF takes no position regarding the validity or scope of any 423 Intellectual Property Rights or other rights that might be claimed to 424 pertain to the implementation or use of the technology described in 425 this document or the extent to which any license under such rights 426 might or might not be available; nor does it represent that it has 427 made any independent effort to identify any such rights. Information 428 on the procedures with respect to rights in RFC documents can be 429 found in BCP 78 and BCP 79. 431 Copies of IPR disclosures made to the IETF Secretariat and any 432 assurances of licenses to be made available, or the result of an 433 attempt made to obtain a general license or permission for the use of 434 such proprietary rights by implementers or users of this 435 specification can be obtained from the IETF on-line IPR repository at 436 http://www.ietf.org/ipr. 438 The IETF invites any interested party to bring to its attention any 439 copyrights, patents or patent applications, or other proprietary 440 rights that may cover technology that may be required to implement 441 this standard. Please address the information to the IETF at ietf- 442 ipr@ietf.org. 444 11. Copyright Notice 446 Copyright (C) The IETF Trust (2008). 448 This document is subject to the rights, licenses and restrictions 449 contained in BCP 78, and except as set forth therein, the authors 450 retain all their rights. 452 This document and the information contained herein are provided on an 453 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 454 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND 455 THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS 456 OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF 457 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 458 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 460 12. Acknowledgments 462 Some of the material in the document is adapted from a proposal for 463 selective updates by Yakov Rekhter, Kannan Varadhan, and Curtis 464 Villamizar. 466 13. Normative References 468 [BGP-4] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway Protocol 469 4 (BGP-4)", RFC 4271, January 2006. 471 [BGP-MP] Bates, T., Chandra, R., Rekhter, Y., and D. Katz, 472 "Multiprotocol Extensions for BGP-4", RFC 4760, January 2007. 474 [BGP-CAP] Chandra, R., Scudder, J., "Capabilities Advertisement with 475 BGP-4", RFC 3392, November 2002. 477 [BGP-RR] Chen, E., "Route Refresh Capability for BGP-4", RFC 2918, 478 September 2000. 480 [RFC-2119] Bradner, S., "Key words for use in RFCs to Indicate 481 Requirement Levels", BCP 14, RFC 2119, March 1997. 483 14. Author Information 485 Enke Chen 486 Cisco Systems, Inc. 487 170 W. Tasman Dr. 488 San Jose, CA 95134 490 Email: enkechen@cisco.com 492 Yakov Rekhter 493 Juniper Networks 494 1194 N. Mathilda Ave 495 Sunnyvale, CA 94089 497 Email: yakov@juniper.net