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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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-22) exists of draft-ietf-idr-flow-spec-v6-09 ** Obsolete normative reference: RFC 5575 (Obsoleted by RFC 8955) ** Obsolete normative reference: RFC 7674 (Obsoleted by RFC 8955) == Outdated reference: A later version (-23) exists of draft-ietf-idr-flowspec-l2vpn-11 == Outdated reference: A later version (-23) exists of draft-ietf-pce-pcep-yang-12 == Outdated reference: A later version (-22) exists of draft-ietf-teas-yang-path-computation-06 Summary: 2 errors (**), 0 flaws (~~), 5 warnings (==), 1 comment (--).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 D. Dhody 3 Internet-Draft Huawei Technologies 4 Intended status: Standards Track A. Farrel 5 Expires: February 16, 2020 Old Dog Consulting 6 Z. Li 7 Huawei Technologies 8 August 15, 2019 10 PCEP Extension for Flow Specification 11 draft-ietf-pce-pcep-flowspec-05 13 Abstract 15 The Path Computation Element (PCE) is a functional component capable 16 of selecting the paths through a traffic engineered network. These 17 paths may be supplied in response to requests for computation, or may 18 be unsolicited instructions issued by the PCE to network elements. 19 Both approaches use the PCE Communication Protocol (PCEP) to convey 20 the details of the computed path. 22 Traffic flows may be categorized and described using "Flow 23 Specifications". RFC 5575 defines the Flow Specification and 24 describes how Flow Specification Components are used to describe 25 traffic flows. RFC 5575 also defines how Flow Specifications may be 26 distributed in BGP to allow specific traffic flows to be associated 27 with routes. 29 This document specifies a set of extensions to PCEP to support 30 dissemination of Flow Specifications. This allows a PCE to indicate 31 what traffic should be placed on each path that it is aware of. 33 Status of This Memo 35 This Internet-Draft is submitted in full conformance with the 36 provisions of BCP 78 and BCP 79. 38 Internet-Drafts are working documents of the Internet Engineering 39 Task Force (IETF). Note that other groups may also distribute 40 working documents as Internet-Drafts. The list of current Internet- 41 Drafts is at https://datatracker.ietf.org/drafts/current/. 43 Internet-Drafts are draft documents valid for a maximum of six months 44 and may be updated, replaced, or obsoleted by other documents at any 45 time. It is inappropriate to use Internet-Drafts as reference 46 material or to cite them other than as "work in progress." 48 This Internet-Draft will expire on February 16, 2020. 50 Copyright Notice 52 Copyright (c) 2019 IETF Trust and the persons identified as the 53 document authors. All rights reserved. 55 This document is subject to BCP 78 and the IETF Trust's Legal 56 Provisions Relating to IETF Documents 57 (https://trustee.ietf.org/license-info) in effect on the date of 58 publication of this document. Please review these documents 59 carefully, as they describe your rights and restrictions with respect 60 to this document. Code Components extracted from this document must 61 include Simplified BSD License text as described in Section 4.e of 62 the Trust Legal Provisions and are provided without warranty as 63 described in the Simplified BSD License. 65 Table of Contents 67 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 68 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 69 3. Procedures for PCE Use of Flow Specifications . . . . . . . . 5 70 3.1. Context for PCE Use of Flow Specifications . . . . . . . 5 71 3.2. Elements of Procedure . . . . . . . . . . . . . . . . . . 6 72 3.2.1. Capability Advertisement . . . . . . . . . . . . . . 6 73 3.2.2. Dissemination Procedures . . . . . . . . . . . . . . 7 74 3.2.3. Flow Specification Synchronization . . . . . . . . . 8 75 4. PCE FlowSpec Capability TLV . . . . . . . . . . . . . . . . . 9 76 5. PCEP FLOWSPEC Object . . . . . . . . . . . . . . . . . . . . 9 77 6. Flow Filter TLV . . . . . . . . . . . . . . . . . . . . . . . 11 78 7. Flow Specification TLVs . . . . . . . . . . . . . . . . . . . 11 79 8. Detailed Procedures . . . . . . . . . . . . . . . . . . . . . 15 80 8.1. Default Behavior and Backward Compatibility . . . . . . . 15 81 8.2. Composite Flow Specifications . . . . . . . . . . . . . . 15 82 8.3. Modifying Flow Specifications . . . . . . . . . . . . . . 16 83 8.4. Multiple Flow Specifications . . . . . . . . . . . . . . 16 84 8.5. Adding and Removing Flow Specifications . . . . . . . . . 16 85 8.6. VPN Identifiers . . . . . . . . . . . . . . . . . . . . . 17 86 8.7. Priorities and Overlapping Flow Specifications . . . . . 17 87 9. PCEP Messages . . . . . . . . . . . . . . . . . . . . . . . . 18 88 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21 89 10.1. PCEP Objects . . . . . . . . . . . . . . . . . . . . . . 21 90 10.1.1. PCEP FLOWSPEC Object Flag Field . . . . . . . . . . 21 91 10.2. PCEP TLV Type Indicators . . . . . . . . . . . . . . . . 21 92 10.3. Flow Specification TLV Type Indicators . . . . . . . . . 22 93 10.4. PCEP Error Codes . . . . . . . . . . . . . . . . . . . . 22 94 10.5. PCE Capability Flag . . . . . . . . . . . . . . . . . . 23 95 11. Implementation Status . . . . . . . . . . . . . . . . . . . . 23 96 12. Security Considerations . . . . . . . . . . . . . . . . . . . 24 97 13. Manageability Considerations . . . . . . . . . . . . . . . . 24 98 13.1. Management of Multiple Flow Specifications . . . . . . . 25 99 13.2. Control of Function through Configuration and Policy . . 25 100 13.3. Information and Data Models . . . . . . . . . . . . . . 26 101 13.4. Liveness Detection and Monitoring . . . . . . . . . . . 26 102 13.5. Verifying Correct Operation . . . . . . . . . . . . . . 26 103 13.6. Requirements on Other Protocols and Functional 104 Components . . . . . . . . . . . . . . . . . . . . . . . 26 105 13.7. Impact on Network Operation . . . . . . . . . . . . . . 27 106 13.8. Other Considerations . . . . . . . . . . . . . . . . . . 27 107 14. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 27 108 15. References . . . . . . . . . . . . . . . . . . . . . . . . . 27 109 15.1. Normative References . . . . . . . . . . . . . . . . . . 27 110 15.2. Informative References . . . . . . . . . . . . . . . . . 28 111 Appendix A. Contributors . . . . . . . . . . . . . . . . . . . . 30 112 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 32 114 1. Introduction 116 [RFC4655] defines the Path Computation Element (PCE), a functional 117 component capable of computing paths for use in traffic engineering 118 networks. PCE was originally conceived for use in Multiprotocol 119 Label Switching (MPLS) for Traffic Engineering (TE) networks to 120 derive the routes of Label Switched Paths (LSPs). However, the scope 121 of PCE was quickly extended to make it applicable to Generalized MPLS 122 (GMPLS) networks, and more recent work has brought other traffic 123 engineering technologies and planning applications into scope (for 124 example, Segment Routing (SR) [I-D.ietf-pce-segment-routing]). 126 [RFC5440] describes the Path Computation Element Communication 127 Protocol (PCEP). PCEP defines the communication between a Path 128 Computation Client (PCC) and a PCE, or between PCE and PCE, enabling 129 computation of path for MPLS-TE LSPs. 131 Stateful PCE [RFC8231] specifies a set of extensions to PCEP to 132 enable control of TE-LSPs by a PCE that retains state about the the 133 LSPs provisioned in the network (a stateful PCE). [RFC8281] 134 describes the setup, maintenance, and teardown of LSPs initiated by a 135 stateful PCE without the need for local configuration on the PCC, 136 thus allowing for a dynamic network that is centrally controlled. 137 [RFC8283] introduces the architecture for PCE as a central controller 138 and describes how PCE can be viewed as a component that performs 139 computation to place 'flows' within the network and decide how these 140 flows are routed. 142 The description of traffic flows by the combination of multiple Flow 143 Specification Components and their dissemination of as traffic flow 144 specifications (Flow Specifications) was introduced for BGP in 145 [RFC5575] and updated (for clarification) in [RFC7674]. A Flow 146 Specification is comprised of traffic filtering rules and actions. 147 The routers that receive a Flow Specification can classify received 148 packets according to the traffic filtering rules and can direct 149 packets based on the actions. 151 When a PCE is used to initiate tunnels (such as TE-LSPs or SR paths) 152 using PCEP, it is important that the head end of the tunnels 153 understands what traffic to place on each tunnel. The data flows 154 intended for a tunnel can be described using Flow Specification 155 Components, and when PCEP is in use for tunnel initiation it makes 156 sense for that same protocol to be used to distribute the Flow 157 Specification Components that describe what data is to flow on those 158 tunnels. 160 This document specifies a set of extensions to PCEP to support 161 dissemination of Flow Specifications Components. For convenience we 162 term the description of a traffic flow using Flow Specification 163 Components as a "Flow Specification" and it must be understood that 164 this is not the same as the same term used in [RFC5575] since no 165 action is explicitly included in the encoding. 167 The extensions defined in this document include the creation, update, 168 and withdrawal of Flow Specifications via PCEP, and can be applied to 169 tunnels initiated by the PCE or to tunnels where control is delegated 170 to the PCE by the PCC. Furthermore, a PCC requesting a new path can 171 include Flow Specifications in the request to indicate the purpose of 172 the tunnel allowing the PCE to factor this in during the path 173 computation. 175 Flow Specifications are carried in TLVs within a new Flow Spec Object 176 defined in this document. The flow filtering rules indicated by the 177 Flow Specifications are mainly defined by BGP Flow Specifications. 179 2. Terminology 181 This document uses the following terms defined in [RFC5440]: PCC, 182 PCE, PCEP Peer. 184 The following term from [RFC5575] is used frequently throughout this 185 document: 187 Flow Specification (FlowSpec): A Flow Specification is an n-tuple 188 consisting of several matching criteria that can be applied to IP 189 traffic, including filters and actions. Each FlowSpec consists of 190 a set of filters and a set of actions. 192 However, in the context of this document, no action is specified as 193 part of the FlowSpec since the action "forward all matching traffic 194 onto the associated path" is implicit. 196 This document uses the terms "stateful PCE" and "active PCE" as 197 advocated in [RFC7399]. 199 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 200 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 201 "OPTIONAL" in this document are to be interpreted as described in BCP 202 14 [RFC2119] [RFC8174] when, and only when, they appear in all 203 capitals, as shown here. 205 3. Procedures for PCE Use of Flow Specifications 207 3.1. Context for PCE Use of Flow Specifications 209 In the PCE architecture there are five steps in the setup and use of 210 LSPs: 212 1. Decide which LSPs to set up. The decision may be made by a user, 213 by a PCC, or by the PCE. There can be a number of triggers for 214 this including user intervention and dynamic response to changes 215 in traffic demands. 217 2. Decide what properties to assign to an LSP. This can include 218 bandwidth reservations, priorities, and DSCP (i.e., MPLS Traffic 219 Class field). This function is also determined by user 220 configuration or response to predicted or observed traffic 221 demands. 223 3. Decide what traffic to put on the LSP. This is effectively 224 determining which traffic flows to assign to which LSPs, and 225 practically, this is closely linked to the first two decisions 226 listed above. 228 4. Cause the LSP to be set up and modified to have the right 229 characteristics. This will usually involve the PCE advising or 230 instructing the PCC which will then signal the LSP across the 231 network. 233 5. Tell the head end what traffic to put on the LSP. This may 234 happen after or at the same time as the LSP is set up. This step 235 is the subject of this document. 237 3.2. Elements of Procedure 239 There are three elements of procedure: 241 o A PCE and a PCC must be able to indicate whether or not they 242 support the use of Flow Specifications. 244 o A PCE or PCC must be able to include Flow Specifications in PCEP 245 messages with clear understanding of the applicability of those 246 Flow Specifications in each case including whether the use of such 247 information is mandatory, constrained, or optional, and how 248 overlapping Flow Specifications will be resolved. 250 o Flow Specification information/state must be synchronized between 251 PCEP peers so that, on recovery, the peers have the same 252 understanding of which Flow Specifications apply. 254 The following subsections describe these points. 256 3.2.1. Capability Advertisement 258 As with most PCEP capability advertisements, the ability to support 259 Flow Specifications can be indicated in the PCEP OPEN message or in 260 IGP PCE capability advertisements. 262 3.2.1.1. PCEP OPEN Message 264 During PCEP session establishment, a PCC or PCE that supports the 265 procedures described in this document announces this fact by 266 including the "PCE FlowSpec Capability" TLV (described in Section 4) 267 in the OPEN Object carried in the PCEP Open message. 269 The presence of the PCE FlowSpec Capability TLV in the OPEN Object in 270 a PCE's OPEN message indicates that the PCE can distribute FlowSpecs 271 to PCCs and can receive FlowSpecs in messages from the PCCs. 273 The presence of the PCE FlowSpec Capability TLV in the OPEN Object in 274 a PCC's OPEN message indicates that the PCC supports the FlowSpec 275 functionality described in this document. 277 If either one of a pair of PCEP peers does not indicate support of 278 the functionality described in this document by not including the PCE 279 FlowSpec Capability TLV in the OPEN Object in its OPEN message, then 280 the other peer MUST NOT include a FlowSpec object in any PCEP message 281 sent to the peer that does not support the procedures. If a FlowSpec 282 object is received even though support has not been indicated, the 283 receiver will respond with a PCErr message reporting the objects 284 containing the FlowSpec as described in [RFC5440]: that is, it will 285 use 'Unknown Object' if it does not support this specification, and 286 'Not supported object' if it supports this specification but has not 287 chosen to support FlowSpec objects on this PCEP session. 289 3.2.1.2. IGP PCE Capabilities Advertisement 291 The ability to advertise support for PCEP and PCE features in IGP 292 advertisements is provided for OSPF in [RFC5088] and for IS-IS in 293 [RFC5089]. The mechanism uses the PCE Discovery TLV which has a PCE- 294 CAP-FLAGS sub-TLV containing bit-flags each of which indicates 295 support for a different feature. 297 This document defines a new PCE-CAP-FLAGS sub-TLV bit, the FlowSpec 298 Capable flag (bit number TBD1). Setting the bit indicates that an 299 advertising PCE supports the procedures defined in this document. 301 Note that while PCE FlowSpec Capability may be advertised during 302 discovery, PCEP speakers that wish to use Flow Specification in PCEP 303 MUST negotiate PCE FlowSpec Capability during PCEP session setup, as 304 specified in Section 3.2.1.1. A PCC MAY initiate PCE FlowSpec 305 Capability negotiation at PCEP session setup even if it did not 306 receive any IGP PCE capability advertisement, and a PCEP peer that 307 advertised support for FlowSpec in the IGP is not obliged to support 308 these procedures on any given PCEP session. 310 3.2.2. Dissemination Procedures 312 This section describes the procedures to support Flow Specifications 313 in PCEP messages. 315 The primary purpose of distributing Flow Specification information is 316 to allow a PCE to indicate to a PCC what traffic it should place on a 317 path (such as an LSP or an SR path). This means that the Flow 318 Specification may be included in: 320 o PCInitiate messages so that an active PCE can indicate the traffic 321 to place on a path at the time that the PCE instantiates the path. 323 o PCUpd messages so that an active PCE can indicate or change the 324 traffic to place on a path that has already been set up. 326 o PCRpt messages so that a PCC can report the traffic that the PCC 327 plans to place on the path. 329 o PCReq messages so that a PCC can indicate what traffic it plans to 330 place on a path at the time it requests the PCE to perform a 331 computation in case that information aids the PCE in its work. 333 o PCRep messages so that a PCE that has been asked to compute a path 334 can suggest which traffic could be placed on a path that a PCC may 335 be about to set up. 337 o PCErr messages so that issues related to paths and the traffic 338 they carry can be reported to the PCE by the PCC, and so that 339 problems with other PCEP messages that carry Flow Specifications 340 can be reported. 342 To carry Flow Specifications in PCEP messages, this document defines 343 a new PCEP object called the PCEP FLOWSPEC Object. The object is 344 OPTIONAL in the messages described above and MAY appear more than 345 once in each message. 347 The PCEP FLOWSPEC Object carries zero or one Flow Filter TLV which 348 describes a traffic flow. 350 The inclusion of multiple PCEP FLOWSPEC Objects allows multiple 351 traffic flows to be placed on a single path. 353 Once a PCE and PCC have established that they can both support the 354 use of Flow Specifications in PCEP messages, such information may be 355 exchanged at any time for new or existing paths. 357 The application and prioritization of Flow Specifications is 358 described in Section 8.7. 360 As per [RFC8231], any attributes of the path received from a PCE are 361 subject to PCC's local policy. This holds good for the Flow 362 Specifications as well. 364 3.2.3. Flow Specification Synchronization 366 The Flow Specifications are carried along with the LSP State 367 information as per [RFC8231] making the Flow Specifications part of 368 the LSP database (LSP-DB). Thus, the synchronization of the Flow 369 Specification information is done as part of LSP-DB synchronization. 370 This may be achieved using normal state synchronization procedures as 371 described in [RFC8231] or enhanced state synchronization procedures 372 as defined in [RFC8232]. 374 The approach selected will be implementation and deployment specific 375 and will depend on issues such as how the databases are constructed 376 and what level of synchronization support is needed. 378 4. PCE FlowSpec Capability TLV 380 The PCE-FLOWSPEC-CAPABILITY TLV is an optional TLV that can be 381 carried in the OPEN Object [RFC5440] to exchange PCE FlowSpec 382 capabilities of PCEP speakers. 384 The format of the PCE-FLOWSPEC-CAPABILITY TLV follows the format of 385 all PCEP TLVs as defined in [RFC5440] and is shown in Figure 1. 387 0 1 2 3 388 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 1 389 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 390 | Type=TBD2 | Length=2 | 391 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 392 | Value=0 | Padding | 393 +---------------------------------------------------------------+ 395 Figure 1: PCE-FLOWSPEC-CAPABILITY TLV format 397 The type of the PCE-FLOWSPEC-CAPABILITY TLV is TBD2 and it has a 398 fixed length of 2 octets. The Value field is set to default value 0. 399 The two bytes of padding MUST be set to zero and ignored on receipt. 401 The inclusion of this TLV in an OPEN object indicates that the sender 402 can perform FlowSpec handling as defined in this document. 404 5. PCEP FLOWSPEC Object 406 The PCEP FLOWSPEC object defined in this document is compliant with 407 the PCEP object format defined in [RFC5440]. It is OPTIONAL in the 408 PCReq, PCRep, PCErr, PCInitiate, PCRpt, and PCUpd messages and MAY be 409 present zero, one, or more times. Each instance of the object 410 specifies a traffic flow. 412 The PCEP FLOWSPEC object carries a FlowSpec filter rule encoded in a 413 TLV (as defined in Section 6. 415 The FLOWSPEC Object-Class is TBD3 (to be assigned by IANA). 417 The FLOWSPEC Object-Type is 1. 419 The format of the body of the PCEP FLOWSPEC object is shown in 420 Figure 2 421 0 1 2 3 422 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 1 423 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 424 | FS-ID | 425 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 426 | AFI | Reserved | Flags |R| 427 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 428 | | 429 // TLVs // 430 | | 431 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 433 Figure 2: PCEP FLOWSPEC Object Body Format 435 FS-ID (32-bits): A PCEP-specific identifier for the FlowSpec 436 information. A PCE or PCC creates an FS-ID for each FlowSpec that it 437 originates, and the value is unique within the scope of that PCE or 438 PCC and is constant for the lifetime of a PCEP session. All 439 subsequent PCEP messages can identify the FlowSpec using the FS-ID. 440 The values 0 and 0xFFFFFFFF are reserved and MUST NOT be used. 442 AFI (16-bits): Address Family Identifier as used in BGP [RFC4760] 443 (AFI=1 for IPv4 or VPNv4, AFI=2 for IPv6 and VPNv6 as per as per 444 [I-D.ietf-idr-flow-spec-v6]). 446 Reserved (8-bits): MUST be set to zero on transmission and ignored on 447 receipt. 449 Flags (8-bits): One flag is currently assigned - 451 R bit: The Remove bit is set when a PCEP FLOWSPEC Object is 452 included in a PCEP message to indicate removal of the Flow 453 Specification from the associated tunnel. If the bit is clear, 454 the Flow Specification is being added or modified. 456 Unassigned bits MUST be set to zero on transmission and ignored on 457 receipt. 459 If the PCEP speaker receives a message with R bit set in FLOWSPEC 460 object and the Flow Specification identified with a FS-ID does not 461 exist, it MUST generate a PCErr with Error-type TBD8 (FlowSpec 462 Error), error-value 4 (Unknown FlowSpec). 464 If the PCEP speaker does not understand or support the AFI in the 465 FLOWSPEC message, the PCEP peer MUST respond with a PCErr message 466 with error-type TBD8 (FlowSpec Error), error-value 2 (Malformed 467 FlowSpec). 469 Following TLVs can be used in the FLOWSPEC object: 471 o Speaker Entity Identifier TLV: As specified in [RFC8232], SPEAKER- 472 ENTITY-ID TLV encodes a unique identifier for the node that does 473 not change during the lifetime of the PCEP speaker. This is used 474 to uniquely identify the FlowSpec originator and thus used in 475 conjunction with FS-ID to uniquely identify the FlowSpec 476 information. This TLV MUST be included. If the TLV is missing, 477 the PCEP peer MUST respond with a PCErr message with error-type 478 TBD8 (FlowSpec Error), error-value 2 (Malformed FlowSpec). 480 o Flow Filter TLV (variable): One TLV MAY be included. The Flow 481 Filter TLV is OPTIONAL when the R bit is set. The TLV MUST be 482 present when the R bit is clear. If the TLV is missing when the R 483 bit is clear, the PCEP peer MUST respond with a PCErr message with 484 error-type TBD8 (FlowSpec Error), error-value 2 (Malformed 485 FlowSpec). 487 6. Flow Filter TLV 489 A new PCEP TLV is defined to convey Flow Specification filtering 490 rules that specify what traffic is carried on a path. The TLV 491 follows the format of all PCEP TLVs as defined in [RFC5440]. The 492 Type field values come from the codepoint space for PCEP TLVs and has 493 the value TBD4. 495 The Value field contains one or more sub-TLVs (the Flow Specification 496 TLVs) as defined in Section 7. Only one Flow Filter TLV can be 497 present and represents the complete definition of a Flow 498 Specification for traffic to be placed on the tunnel indicated by the 499 PCEP message in which the PCEP Flow Spec Object is carried. The set 500 of Flow Specification TLVs in a single instance of a Flow Filter TLV 501 are combined to indicate the specific Flow Specification. 503 Further Flow Specifications can be included in a PCEP message by 504 including additional Flow Spec objects. 506 7. Flow Specification TLVs 508 The Flow Filter TLV carries one or more Flow Specification TLV. The 509 Flow Specification TLV follows the format of all PCEP TLVs as defined 510 in [RFC5440], however, the Type values are selected from a separate 511 IANA registry (see Section 10) rather than from the common PCEP TLV 512 registry. 514 Type values are chosen so that there can be commonality with Flow 515 Specifications defined for use with BGP [RFC5575]. This is possible 516 because the BGP Flow Spec encoding uses a single octet to encode the 517 type where as PCEP uses two octets. Thus the space of values for the 518 Type field is partitioned as shown in Figure 3. 520 Range | 521 ---------------+--------------------------------------------------- 522 0 | Reserved - must not be allocated. 523 | 524 1 .. 255 | Per BGP registry defined by [RFC5575] and 525 | [I-D.ietf-idr-flow-spec-v6]. 526 | Not to be allocated in this registry. 527 | 528 256 .. 65535 | New PCEP Flow Specifications allocated according 529 | to the registry defined in this document. 531 Figure 3: Flow Specification TLV Type Ranges 533 [RFC5575] created the registry "Flow Spec Component Types" and made 534 allocations to it. [I-D.ietf-idr-flow-spec-v6] requested for another 535 registry "Flow Spec IPv6 Component Types" and requested initial 536 allocations in it. If the AFI (in the FLOWSPEC object) is set to 537 IPv4, the range 1..255 is as per "Flow Spec Component Types" 538 [RFC5575]; if the AFI is set to IPv6, the range 1..255 is as per 539 "Flow Spec IPv6 Component Types" [I-D.ietf-idr-flow-spec-v6]. When 540 future BGP specifications (such as [I-D.ietf-idr-flowspec-l2vpn]) 541 make further allocations to the aforementioned registries, they are 542 also inherited to be used in PCEP. 544 The content of the Value field in each TLV is specific to the type/ 545 AFI and describes the parameters of the Flow Specification. The 546 definition of the format of many of these Value fields is inherited 547 from BGP specifications. Specifically, the inheritance is from 548 [RFC5575] and [I-D.ietf-idr-flow-spec-v6], but may also be inherited 549 from future BGP specifications. 551 When multiple Flow Specification TLVs are present in a single Flow 552 Filter TLV they are combined to produce a more detailed description 553 of a flow. For examples and rules about how this is achieved, see 554 [RFC5575]. 556 An implementation that receives a PCEP message carrying a Flow 557 Specification TLV with a type value that it does not recognize or 558 does not support MUST respond with a PCErr message with error-type 559 TBD8 (FlowSpec Error), error-value 1 (Unsupported FlowSpec) and MUST 560 NOT install the Flow Specification. 562 When used in other protocols (such as BGP) these Flow Specifications 563 are also associated with actions to indicate how traffic matching the 564 Flow Specification should be treated. In PCEP, however, the only 565 action is to associate the traffic with a tunnel and to forward 566 matching traffic on to that path, so no encoding of an action is 567 needed. 569 Section 8.7 describes how overlapping Flow Specifications are 570 prioritized and handled. 572 All Flow Specification TLVs with Types in the range 1 to 255 have 573 Values defined for use in BGP (for example, in [RFC5575], 574 [I-D.ietf-idr-flow-spec-v6], and [I-D.ietf-idr-flowspec-l2vpn]) and 575 are set using the BGP encoding, but without the type octet (the 576 relevant information is in the Type field of the TLV). The Value 577 field is padded with trailing zeros to achieve 4-byte alignment. 579 This document defines following new types - 581 +-------+-------------------------+-----------------------------+ 582 | Type | Description | Value defined in | 583 | | | | 584 +-------+-------------------------+-----------------------------+ 585 | TBD5 | Route Distinguisher | [This.I-D] | 586 +-------+-------------------------+-----------------------------+ 587 | TBD6 | IPv4 Multicast Flow | [This.I-D] | 588 +-------+-------------------------+-----------------------------+ 589 | TBD7 | IPv6 Multicast Flow | [This.I-D] | 590 +-------+-------------------------+-----------------------------+ 592 Figure 4: Table of Flow Specification TLV Types defined in this 593 document 595 To allow identification of a VPN in PCEP via a Route Distinguisher 596 (RD) [RFC4364] a new TLV - ROUTE-DISTINGUISHER TLV is defined in this 597 document. A Flow Specification TLV with Type TBD5 (ROUTE- 598 DISTINGUISHER TLV) carries a RD Value, used to identify that other 599 flow filter information (for example, an IPv4 destination prefix) is 600 associated with a specific VPN identified by the RD. See Section 8.6 601 for further discussion of VPN identification. 603 0 1 2 3 604 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 1 605 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 606 | Type=[TBD5] | Length=8 | 607 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 608 | Route Distinguisher | 609 | | 610 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 612 Figure 5: The Format of the ROUTE-DISTINGUISHER TLV 614 The format of RD is as per [RFC4364]. 616 Although it may be possible to describe a multicast Flow 617 Specification from the combination of other Flow Specification TLVs 618 with specific values, it is more convenient to use a dedicated Flow 619 Specification TLV. Flow Specification TLVs with Type values TBD6 and 620 TBD7 are used to identify a multicast flow for IPv4 and IPv6 621 respectively. The Value field is encoded as shown in Figure 6. 623 0 1 2 3 624 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 1 625 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 626 | Reserved |S|G| Src Mask Len | Grp Mask Len | 627 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 628 ~ Source Address ~ 629 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 630 ~ Group multicast Address ~ 631 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 633 Figure 6: Multicast Flow Specification TLV Encoding 635 The address fields and address mask lengths of the two Multicast Flow 636 Specification TLVs contain source and group prefixes for matching 637 against packet flows noting that the two address fields are 32 bits 638 for the IPv4 Multicast Flow and 128 bits for the IPv6 Multicast Flow. 640 The Reserved field MUST be set to zero and ignored on receipt. 642 Two flags (S and G) are defined. They have the common meanings for 643 wildcarding in multicast. If the S bit is set, then source 644 wildcarding is in use and the values in the Source Mask Length and 645 Source Address fields MUST be ignored. If the G bit is set, then 646 group wildcarding is in use and the values in the Group Mask Length 647 and Group multicast Address fields MUST be ignored. The G bit MUST 648 NOT be set unless the S bit is also set: if a Multicast Flow 649 Specification TLV is received with S bit = 0 and G bit = 1 the 650 receiver SHOULD respond with a PCErr with Error-type TBD8 (FlowSpec 651 Error) and error-value 2 (Malformed FlowSpec). 653 The three multicast mappings may be achieved as follows: 655 (S, G) - S bit = 0, G bit = 0, the Source Address and Group 656 multicast Address prefixes are both used to define the multicast 657 flow. 659 (*, G) - S bit = 1, G bit = 0, the Group multicast Address prefix, 660 but the Source Address prefix is ignored. 662 (*, *) = S bit = 1, G bit = 1, the Source Address and Group 663 multicast Address prefixes are both ignored. 665 8. Detailed Procedures 667 This section outlines some specific detailed procedures for using the 668 protocol extensions defined in this document. 670 8.1. Default Behavior and Backward Compatibility 672 The default behavior is that no Flow Specification is applied to a 673 tunnel. That is, the default is that the Flow Spec object is not 674 used as is the case in all systems before the implementation of this 675 specification. 677 In this case it is a local matter (such as through configuration) how 678 tunnel head ends are instructed what traffic to place on a tunnel. 680 [RFC5440] describes how receivers respond when they see unknown PCEP 681 objects. 683 8.2. Composite Flow Specifications 685 Flow Specifications may be represented by a single Flow Specification 686 TLV or may require a more complex description using multiple Flow 687 Specification TLVs. For example, a flow indicated by a source- 688 destination pair of IPv6 addresses would be described by the 689 combination of Destination IPv6 Prefix and Source IPv6 Prefix Flow 690 Specification TLVs. 692 8.3. Modifying Flow Specifications 694 A PCE may want to modify a Flow Specification associated with a 695 tunnel, or a PCC may want to report a change to the Flow 696 Specification it is using with a tunnel. 698 It is important that the specific Flow Specification is identified so 699 that it is clear that this is a modification of an existing flow and 700 not the addition of a new flow as described in Section 8.4. The FS- 701 ID field of the PCEP Flow Spec Object is used to identify a specific 702 Flow Specification. 704 When modifying a Flow Specification, all Flow Specification TLVs for 705 the intended specification of the flow MUST be included in the PCEP 706 Flow Spec Object and the FS-ID MUST be retained from the previous 707 description of the flow. 709 8.4. Multiple Flow Specifications 711 It is possible that multiple flows will be place on a single tunnel. 712 In some cases it is possible to to define these within a single PCEP 713 Flow Spec Object: for example, two Destination IPv4 Prefix TLVs could 714 be included to indicate that packets matching either prefix are 715 acceptable. PCEP would consider this as a single Flow Specification 716 identified by a single FS-ID. 718 In other scenarios the use of multiple Flow Specification TLVs would 719 be confusing. For example, if flows from A to B and from C to D are 720 to be included then using two Source IPv4 Prefix TLVs and two 721 Destination IPv4 Prefix TLVs would be confusing (are flows from A to 722 D included?). In these cases, each Flow Specification is carried in 723 its own PCEP Flow Spec Object with multiple objects present on a 724 single PCEP message. Use of separate objects also allows easier 725 removal and modification of Flow Specifications. 727 8.5. Adding and Removing Flow Specifications 729 The Remove bit in the the PCEP Flow Spec Object is left clear when a 730 Flow Specification is being added or modified. 732 To remove a Flow Specification, a PCEP Flow Spec Object is included 733 with the FS-ID matching the one being removed, and the R bit set to 734 indicate removal. In this case it is not necessary to include any 735 Flow Specification TLVs. 737 If the R bit is set and Flow Specification TLVs are present an 738 implementation MAY ignore them. If the implementation checks the 739 Flow Specification TLVs against those recorded for the FS-ID of the 740 Flow Specification being removed and finds a mismatch, the Flow 741 Specification MUST still be removed and the implementation SHOULD 742 record a local exception or log. 744 8.6. VPN Identifiers 746 VPN instances are identified in BGP using Route Distinguishers (RDs) 747 [RFC4364]. These values are not normally considered to have any 748 meaning outside of the network, and they are not encoded in data 749 packets belonging to the VPNs. However, RDs provide a useful way of 750 identifying VPN instances and are often manually or automatically 751 assigned to VPNs as they are provisioned. 753 Thus the RD provides a useful way to indicate that traffic for a 754 particular VPN should be placed on a given tunnel. The tunnel head 755 end will need to interpret this Flow Specification not as a filter on 756 the fields of data packets, but using the other mechanisms that it 757 already uses to identify VPN traffic. This could be based on the 758 incoming port (for port-based VPNs) or may leverage knowledge of the 759 VRF that is in use for the traffic. 761 8.7. Priorities and Overlapping Flow Specifications 763 Flow specifications can overlap. For example, two different flow 764 specifications may be identical except for the length of the prefix 765 in the destination address. In these cases the PCC must determine 766 how to prioritize the flow specifications so as to know to which path 767 to assign packets that match both flow specifications. That is, the 768 PCC must assign a precedence to the flow specifications so that it 769 checks each incoming packet for a match in a predictable order. 771 The processing of BGP Flow Specifications is described in [RFC5575]. 772 Section 5.1 of that document explains the order of traffic filtering 773 rules to be executed by an implementation of that specification. 775 PCCs MUST apply the same ordering rules as defined in [RFC5575]. 777 Section 13.1 of this document covers manageability considerations 778 relevant to the prioritized ordering of flow specifications. 780 An implementation that receives a PCEP message carrying a Flow 781 Specification that it cannot resolve against other Flow 782 Specifications already installed MUST respond with a PCErr message 783 with error-type TBD8 (FlowSpec Error), error-value 3 (Unresolvable 784 conflict) and MUST NOT install the Flow Specification. 786 9. PCEP Messages 788 The figures in this section use the notation defined in [RFC5511]. 790 The FLOWSPEC Object is OPTIONAL and MAY be carried in the PCEP 791 messages. 793 The PCInitiate message is defined in [RFC8281] and updated as below: 795 ::= 796 798 Where: 799 ::= 800 [] 802 ::= 803 ( | 804 ) 806 ::= 807 808 [] 809 810 [] 811 [] 813 Where: 814 ::= [] 816 The PCUpd message is defined in [RFC8231] and updated as below: 818 ::= 819 821 Where: 822 ::= 823 [] 825 ::= 826 827 828 [] 830 Where: 831 ::= 833 ::= [] 835 The PCRpt message is defined in [RFC8231] and updated as below: 837 ::= 838 840 Where: 841 ::= [] 843 ::= [] 844 845 846 [] 848 Where: 849 ::= 850 [] 851 853 ::= [] 855 The PCReq message is defined in [RFC5440] and updated in [RFC8231], 856 it is further updated below for flow specification: 858 ::= 859 [] 860 862 Where: 863 ::= [] 865 ::= [] 867 ::= 868 869 [] 870 [] 871 [] 872 [] 873 [[]] 874 [] 875 [] 876 [] 878 Where: 879 ::= [] 881 The PCRep message is defined in [RFC5440] and updated in [RFC8231], 882 it is further updated below for flow specification: 884 ::= 885 887 Where: 888 ::=[] 890 ::= 891 [] 892 [] 893 [] 894 [] 895 [] 897 Where: 898 ::= [] 900 10. IANA Considerations 902 IANA maintains the "Path Computation Element Protocol (PCEP) Numbers" 903 registry. This document requests IANA actions to allocate code 904 points for the protocol elements defined in this document. 906 10.1. PCEP Objects 908 Each PCEP object has an Object-Class and an Object-Type. IANA 909 maintains a subregistry called "PCEP Objects". IANA is requested to 910 make an assignment from this subregistry as follows: 912 Object-Class | Value Name | Object-Type | Reference 913 -------------+-------------+------------------------+---------------- 914 TBD3 | FLOWSPEC | 0: Reserved | [This.I-D] 915 | | 1: Flow Specification | [This.I-D] 917 10.1.1. PCEP FLOWSPEC Object Flag Field 919 This document requests that a new sub-registry, named "FLOW SPEC 920 Object Flag Field", is created within the "Path Computation Element 921 Protocol (PCEP) Numbers" registry to manage the Flag field of the 922 FLOWSPEC object. New values are to be assigned by Standards Action 923 [RFC8126]. Each bit should be tracked with the following qualities: 925 o Bit number (counting from bit 0 as the most significant bit) 927 o Capability description 929 o Defining RFC 931 The following values are defined in this document: 933 Bit Description Reference 935 31 Remove (R-bit) [This.I-D] 937 10.2. PCEP TLV Type Indicators 939 IANA maintains a subregistry called "PCEP TLV Type Indicators". IANA 940 is requested to make an assignment from this subregistry as follows: 942 Value | Meaning | Reference 943 --------+------------------------------+------------- 944 TBD2 | PCE-FLOWSPEC-CAPABILITY TLV | [This.I-D] 945 TBD4 | FLOW FILTER TLV | [This.I-D] 947 10.3. Flow Specification TLV Type Indicators 949 IANA is requested to create a new subregistry call the "PCEP Flow 950 Specification TLV Type Indicators" registry. 952 Allocations from this registry are to be made according to the 953 following assignment policies [RFC8126]: 955 Range | Assignment policy 956 ---------------+--------------------------------------------------- 957 0 | Reserved - must not be allocated. 958 | 959 1 .. 255 | Reserved - must not be allocated. 960 | Usage mirrors the BGP FlowSpec registry [RFC5575] 961 | & [I-D.ietf-idr-flow-spec-v6]. 962 | 963 256 .. 64506 | Specification Required 964 | 965 64507 .. 65531 | First Come First Served 966 | 967 65532 .. 65535 | Experimental 969 IANA is requested to pre-populate this registry with values defined 970 in this document as follows, taking the new values from the range 256 971 to 64506: 973 Value | Meaning 974 -------+------------------------ 975 TBD5 | Route Distinguisher 976 TBD6 | IPv4 Multicast 977 TBD7 | IPv6 Multicast 979 10.4. PCEP Error Codes 981 IANA maintains a subregistry called "PCEP-ERROR Object Error Types 982 and Values". Entries in this subregistry are described by Error-Type 983 and Error-value. IANA is requested to make the following assignment 984 from this subregistry: 986 Error-| Meaning | Error-value | Reference 987 Type | | | 988 -------+--------------------+----------------------------+----------- 989 TBD8 | FlowSpec error | 0: Unassigned | [This.I-D] 990 | | 1: Unsupported FlowSpec | [This.I-D] 991 | | 2: Malformed FlowSpec | [This.I-D] 992 | | 3: Unresolvable conflict | [This.I-D] 993 | | 4: Unknown FlowSpec | [This.I-D] 994 | | 5-255: Unassigned | [This.I-D] 996 10.5. PCE Capability Flag 998 IANA maintains a subregistry called "Open Shortest Path First v2 999 (OSPFv2) Parameters" with a sub-registry called "Path Computation 1000 Element (PCE) Capability Flags". IANA is requested to assign a new 1001 capability bit from this registry as follows: 1003 Bit | Capability Description | Reference 1004 -------+-------------------------------+------------ 1005 TBD1 | FlowSpec | [This.I-D] 1007 11. Implementation Status 1009 [NOTE TO RFC EDITOR : This whole section and the reference to RFC 1010 7942 is to be removed before publication as an RFC] 1012 This section records the status of known implementations of the 1013 protocol defined by this specification at the time of posting of this 1014 Internet-Draft, and is based on a proposal described in [RFC7942]. 1015 The description of implementations in this section is intended to 1016 assist the IETF in its decision processes in progressing drafts to 1017 RFCs. Please note that the listing of any individual implementation 1018 here does not imply endorsement by the IETF. Furthermore, no effort 1019 has been spent to verify the information presented here that was 1020 supplied by IETF contributors. This is not intended as, and must not 1021 be construed to be, a catalog of available implementations or their 1022 features. Readers are advised to note that other implementations may 1023 exist. 1025 According to [RFC7942], "this will allow reviewers and working groups 1026 to assign due consideration to documents that have the benefit of 1027 running code, which may serve as evidence of valuable experimentation 1028 and feedback that have made the implemented protocols more mature. 1029 It is up to the individual working groups to use this information as 1030 they see fit". 1032 At the time of posting the -04 version of this document, there are no 1033 known implementations of this mechanism. It is believed that two 1034 vendors are considering prototype implementations, but these plans 1035 are too vague to make any further assertions. 1037 12. Security Considerations 1039 We may assume that a system that utilizes a remote PCE is subject to 1040 a number of vulnerabilities that could allow spurious LSPs or SR 1041 paths to be established or that could result in existing paths being 1042 modified or torn down. Such systems, therefore, apply security 1043 considerations as described in [RFC5440], [RFC6952], and [RFC8253]. 1045 The description of Flow Specifications associated with paths set up 1046 or controlled by a PCE add a further detail that could be attacked 1047 without tearing down LSPs or SR paths, but causing traffic to be 1048 misrouted within the network. Therefore, the use of the security 1049 mechanisms for PCEP referenced above is important. 1051 Visibility into the information carried in PCEP does not have direct 1052 privacy concerns for end-users' data, however, knowledge of how data 1053 is routed in a network may make that data more vulnerable. Of 1054 course, the ability to interfere with the way data is routed also 1055 makes the data more vulnerable. Furthermore, knowledge of the 1056 connected end-points (such as multicast receivers or VPN sites) is 1057 usually considered private customer information. Therefore, 1058 implementations or deployments concerned to protect privacy MUST 1059 apply the mechanisms described in the documents referenced above. 1061 Experience with Flow Specifications in BGP systems indicates that 1062 they can become complex and that the overlap of Flow Specifications 1063 installed in different orders can lead to unexpected results. 1064 Although this is not directly a security issue per se, the confusion 1065 and unexpected forwarding behavior may be engineered or exploited by 1066 an attacker. Therefore, implementers and operators SHOULD pay 1067 careful attention to the Manageability Considerations described in 1068 Section 13. 1070 13. Manageability Considerations 1072 The feature introduced by this document enables operational 1073 manageability of networks operated in conjunction with a PCE and 1074 using PCEP. Without this feature, but in the case of a stateful 1075 active PCE or with PCE-initiated services, additional manual 1076 configuration is needed to tell the head-ends what traffic to place 1077 on the network services (LSPs, SR paths, etc.). 1079 This section follows the advice and guidance of [RFC6123]. 1081 13.1. Management of Multiple Flow Specifications 1083 Experience with flow specification in BGP suggests that there can be 1084 a lot of complexity when two or more flow specifications overlap. 1085 This can arise, for example, with addresses indicated using prefixes, 1086 and could cause confusion about what traffic should be placed on 1087 which path. Unlike the behavior in a distributed routing system, it 1088 is not important that each head-end implementation applies the same 1089 rules to disambiguate overlapping Flow Specifications, but it is 1090 important that: 1092 o A network operator can easily find out what traffic is being 1093 placed on which path and why. This will facilitate analysis of 1094 the network and diagnosis of faults. 1096 o A PCE is able to correctly predict the effect of instructions it 1097 gives to a PCC. 1099 To that end, a PCC MUST enable an operator to view the the Flow 1100 Specifications that it has installed, and these MUST be presented in 1101 order of precedence such that when two Flow Specifications overlap, 1102 the one that will be serviced with higher precedence is presented to 1103 the operator first. 1105 A discussion of precedence ordering for flow specifications is found 1106 in Section 8.7. 1108 13.2. Control of Function through Configuration and Policy 1110 Support for the function described in this document implies that a 1111 functional element that is capable of requesting a PCE to compute and 1112 control a path is also able to configure the specification of what 1113 traffic should be placed on that path. Where there is a human 1114 involved in this action, configuration of the Flow Specification must 1115 be available through an interface (such as a graphical user interface 1116 or a command line interface). Where a distinct software component 1117 (i.e., one not co-implemented with the PCE) is used, an protocol 1118 mechanism will be required that could be PCEP itself or could be a 1119 data model such as extensions to the YANG model for requesting path 1120 computation [I-D.ietf-teas-yang-path-computation]. 1122 Implementations MAY be constructed with a configurable switch to say 1123 whether they support the functions defined in this document. 1124 Otherwise, such implementations MUST support indicate that they 1125 support the function as described in Section 4. If an implementation 1126 supports configurable support of this function, that support MAY be 1127 configurable per peer or just once for the whole implementation. 1129 As mentioned in Section 13.1, a PCE implementation SHOULD provide a 1130 mechanism to configure variations in the precedence ordering of Flow 1131 Specifications per PCC. 1133 13.3. Information and Data Models 1135 The YANG model in [I-D.ietf-pce-pcep-yang] can be used to model and 1136 monitor PCEP states and messages. To make that YANG model useful for 1137 the extensions described in this document it will need to be 1138 augmented to cover the new protocol elements. 1140 Similarly, as noted in Section 13.2, the YANG model defined in 1141 [I-D.ietf-teas-yang-path-computation] could be extended to allow 1142 specification of Flow Specifications. 1144 Finally, as mentioned in Section 13.1, a PCC implementation SHOULD 1145 provide a mechanism to allow an operator to read the Flow 1146 Specifications from a PCC and to understand in what order they will 1147 be executed. This could be achieved using a new YANG model. 1149 13.4. Liveness Detection and Monitoring 1151 The extensions defined in this document do not require any additional 1152 liveness detection an monitoring support. See [RFC5440] and 1153 [RFC5886] for more information. 1155 13.5. Verifying Correct Operation 1157 The chief element of operation that needs to be verified (in addition 1158 to the operation of the protocol elements as described in [RFC5440]) 1159 is the installation, precedence, and correct operation of the Flow 1160 Specifications at a PCC. 1162 In addition to the YANG model for reading Flow Specifications 1163 described in Section 13.3, tools may be needed to inject Operations 1164 and Management (OAM) traffic at the PCC that matches specific 1165 criteria so that it can be monitored as travelling along the desired 1166 path. Such tools are outside the scope of this document. 1168 13.6. Requirements on Other Protocols and Functional Components 1170 This document places no requirements on other protocols or 1171 components. 1173 13.7. Impact on Network Operation 1175 The use of the features described in this document clearly have an 1176 important impact on network traffic since they cause traffic to be 1177 routed on specific paths in the network. However, in practice, these 1178 changes make no direct changes to the network operation because 1179 traffic is already placed on those paths using some pre-existing 1180 configuration mechanism. Thus, the significant change is the 1181 reduction in mechanisms that have to be applied, rather than a change 1182 to how the traffic is passed through the network. 1184 13.8. Other Considerations 1186 No other manageability considerations are known at this time. 1188 14. Acknowledgements 1190 Thanks to Julian Lucek, Sudhir Cheruathur, Olivier Dugeon, Jayant 1191 Agarwal, and Jeffrey Zhang for useful discussions. 1193 15. References 1195 15.1. Normative References 1197 [I-D.ietf-idr-flow-spec-v6] 1198 McPherson, D., Raszuk, R., Pithawala, B., 1199 akarch@cisco.com, a., and S. Hares, "Dissemination of Flow 1200 Specification Rules for IPv6", draft-ietf-idr-flow-spec- 1201 v6-09 (work in progress), November 2017. 1203 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1204 Requirement Levels", BCP 14, RFC 2119, 1205 DOI 10.17487/RFC2119, March 1997, 1206 . 1208 [RFC4760] Bates, T., Chandra, R., Katz, D., and Y. Rekhter, 1209 "Multiprotocol Extensions for BGP-4", RFC 4760, 1210 DOI 10.17487/RFC4760, January 2007, 1211 . 1213 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 1214 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 1215 DOI 10.17487/RFC5440, March 2009, 1216 . 1218 [RFC5511] Farrel, A., "Routing Backus-Naur Form (RBNF): A Syntax 1219 Used to Form Encoding Rules in Various Routing Protocol 1220 Specifications", RFC 5511, DOI 10.17487/RFC5511, April 1221 2009, . 1223 [RFC5575] Marques, P., Sheth, N., Raszuk, R., Greene, B., Mauch, J., 1224 and D. McPherson, "Dissemination of Flow Specification 1225 Rules", RFC 5575, DOI 10.17487/RFC5575, August 2009, 1226 . 1228 [RFC7674] Haas, J., Ed., "Clarification of the Flowspec Redirect 1229 Extended Community", RFC 7674, DOI 10.17487/RFC7674, 1230 October 2015, . 1232 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1233 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1234 May 2017, . 1236 [RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody, 1237 "PCEPS: Usage of TLS to Provide a Secure Transport for the 1238 Path Computation Element Communication Protocol (PCEP)", 1239 RFC 8253, DOI 10.17487/RFC8253, October 2017, 1240 . 1242 15.2. Informative References 1244 [I-D.ietf-idr-flowspec-l2vpn] 1245 Weiguo, H., Eastlake, D., Uttaro, J., Litkowski, S., and 1246 S. Zhuang, "BGP Dissemination of L2VPN Flow Specification 1247 Rules", draft-ietf-idr-flowspec-l2vpn-11 (work in 1248 progress), July 2019. 1250 [I-D.ietf-pce-pcep-yang] 1251 Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A 1252 YANG Data Model for Path Computation Element 1253 Communications Protocol (PCEP)", draft-ietf-pce-pcep- 1254 yang-12 (work in progress), July 2019. 1256 [I-D.ietf-pce-segment-routing] 1257 Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W., 1258 and J. Hardwick, "PCEP Extensions for Segment Routing", 1259 draft-ietf-pce-segment-routing-16 (work in progress), 1260 March 2019. 1262 [I-D.ietf-teas-yang-path-computation] 1263 Busi, I. and S. Belotti, "Yang model for requesting Path 1264 Computation", draft-ietf-teas-yang-path-computation-06 1265 (work in progress), July 2019. 1267 [RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private 1268 Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February 1269 2006, . 1271 [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation 1272 Element (PCE)-Based Architecture", RFC 4655, 1273 DOI 10.17487/RFC4655, August 2006, 1274 . 1276 [RFC5088] Le Roux, JL., Ed., Vasseur, JP., Ed., Ikejiri, Y., and R. 1277 Zhang, "OSPF Protocol Extensions for Path Computation 1278 Element (PCE) Discovery", RFC 5088, DOI 10.17487/RFC5088, 1279 January 2008, . 1281 [RFC5089] Le Roux, JL., Ed., Vasseur, JP., Ed., Ikejiri, Y., and R. 1282 Zhang, "IS-IS Protocol Extensions for Path Computation 1283 Element (PCE) Discovery", RFC 5089, DOI 10.17487/RFC5089, 1284 January 2008, . 1286 [RFC5886] Vasseur, JP., Ed., Le Roux, JL., and Y. Ikejiri, "A Set of 1287 Monitoring Tools for Path Computation Element (PCE)-Based 1288 Architecture", RFC 5886, DOI 10.17487/RFC5886, June 2010, 1289 . 1291 [RFC6123] Farrel, A., "Inclusion of Manageability Sections in Path 1292 Computation Element (PCE) Working Group Drafts", RFC 6123, 1293 DOI 10.17487/RFC6123, February 2011, 1294 . 1296 [RFC6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of 1297 BGP, LDP, PCEP, and MSDP Issues According to the Keying 1298 and Authentication for Routing Protocols (KARP) Design 1299 Guide", RFC 6952, DOI 10.17487/RFC6952, May 2013, 1300 . 1302 [RFC7399] Farrel, A. and D. King, "Unanswered Questions in the Path 1303 Computation Element Architecture", RFC 7399, 1304 DOI 10.17487/RFC7399, October 2014, 1305 . 1307 [RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running 1308 Code: The Implementation Status Section", BCP 205, 1309 RFC 7942, DOI 10.17487/RFC7942, July 2016, 1310 . 1312 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 1313 Writing an IANA Considerations Section in RFCs", BCP 26, 1314 RFC 8126, DOI 10.17487/RFC8126, June 2017, 1315 . 1317 [RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path 1318 Computation Element Communication Protocol (PCEP) 1319 Extensions for Stateful PCE", RFC 8231, 1320 DOI 10.17487/RFC8231, September 2017, 1321 . 1323 [RFC8232] Crabbe, E., Minei, I., Medved, J., Varga, R., Zhang, X., 1324 and D. Dhody, "Optimizations of Label Switched Path State 1325 Synchronization Procedures for a Stateful PCE", RFC 8232, 1326 DOI 10.17487/RFC8232, September 2017, 1327 . 1329 [RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path 1330 Computation Element Communication Protocol (PCEP) 1331 Extensions for PCE-Initiated LSP Setup in a Stateful PCE 1332 Model", RFC 8281, DOI 10.17487/RFC8281, December 2017, 1333 . 1335 [RFC8283] Farrel, A., Ed., Zhao, Q., Ed., Li, Z., and C. Zhou, "An 1336 Architecture for Use of PCE and the PCE Communication 1337 Protocol (PCEP) in a Network with Central Control", 1338 RFC 8283, DOI 10.17487/RFC8283, December 2017, 1339 . 1341 Appendix A. Contributors 1343 Shankara 1344 Huawei Technologies 1345 Divyashree Techno Park, 1346 Whitefield Bangalore, 1347 Karnataka 1348 560066 1349 India 1351 Email: shankara@huawei.com 1353 Qiandeng Liang 1354 Huawei Technologies 1355 101 Software Avenue, 1356 Yuhuatai District 1357 Nanjing 1358 210012 1359 China 1361 Email: liangqiandeng@huawei.com 1363 Cyril Margaria 1364 Juniper Networks 1365 200 Somerset Corporate Boulevard, Suite 4001 1366 Bridgewater, NJ 1367 08807 1368 USA 1370 Email: cmargaria@juniper.net 1372 Colby Barth 1373 Juniper Networks 1374 200 Somerset Corporate Boulevard, Suite 4001 1375 Bridgewater, NJ 1376 08807 1377 USA 1379 Email: cbarth@juniper.net 1381 Xia Chen 1382 Huawei Technologies 1383 Huawei Bld., No.156 Beiqing Rd. 1384 Beijing 1385 100095 1386 China 1388 Email: jescia.chenxia@huawei.com 1390 Shunwan Zhuang 1391 Huawei Technologies 1392 Huawei Bld., No.156 Beiqing Rd. 1393 Beijing 1394 100095 1395 China 1397 Email: zhuangshunwan@huawei.com 1399 Cheng Li 1400 Huawei Technologies 1401 Huawei Campus, No. 156 Beiqing Rd. 1402 Beijing 100095 1403 China 1405 Email: chengli13@huawei.com 1407 Authors' Addresses 1409 Dhruv Dhody 1410 Huawei Technologies 1411 Divyashree Techno Park, Whitefield 1412 Bangalore, Karnataka 560066 1413 India 1415 Email: dhruv.ietf@gmail.com 1417 Adrian Farrel 1418 Old Dog Consulting 1420 Email: adrian@olddog.co.uk 1422 Zhenbin Li 1423 Huawei Technologies 1424 Huawei Bld., No.156 Beiqing Rd. 1425 Beijing 100095 1426 China 1428 Email: lizhenbin@huawei.com