idnits 2.17.00 (12 Aug 2021) /tmp/idnits63240/draft-ietf-pce-binding-label-sid-02.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (March 9, 2020) is 803 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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-22) exists of draft-ietf-spring-segment-routing-policy-06 == Outdated reference: draft-ietf-pce-pcep-extension-for-pce-controller has been published as RFC 9050 == Outdated reference: A later version (-18) exists of draft-ietf-pce-pcep-yang-13 Summary: 0 errors (**), 0 flaws (~~), 4 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 PCE Working Group S. Sivabalan 3 Internet-Draft C. Filsfils 4 Intended status: Standards Track Cisco Systems, Inc. 5 Expires: September 10, 2020 J. Tantsura 6 Apstra, Inc. 7 J. Hardwick 8 Metaswitch Networks 9 S. Previdi 10 C. Li 11 Huawei Technologies 12 March 9, 2020 14 Carrying Binding Label/Segment-ID in PCE-based Networks. 15 draft-ietf-pce-binding-label-sid-02 17 Abstract 19 In order to provide greater scalability, network opacity, and service 20 independence, Segment Routing (SR) utilizes a Binding Segment 21 Identifier (BSID). It is possible to associate a BSID to RSVP-TE 22 signaled Traffic Engineering Label Switching Path or binding Segment- 23 ID (SID) to SR Traffic Engineering path. Such a binding label/SID 24 can be used by an upstream node for steering traffic into the 25 appropriate TE path to enforce SR policies. This document proposes 26 an approach for reporting binding label/SID to Path Computation 27 Element (PCE) for supporting PCE-based Traffic Engineering policies. 29 Requirements Language 31 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 32 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 33 "OPTIONAL" in this document are to be interpreted as described in BCP 34 14 [RFC2119] [RFC8174] when, and only when, they appear in all 35 capitals, as shown here. 37 Status of This Memo 39 This Internet-Draft is submitted in full conformance with the 40 provisions of BCP 78 and BCP 79. 42 Internet-Drafts are working documents of the Internet Engineering 43 Task Force (IETF). Note that other groups may also distribute 44 working documents as Internet-Drafts. The list of current Internet- 45 Drafts is at https://datatracker.ietf.org/drafts/current/. 47 Internet-Drafts are draft documents valid for a maximum of six months 48 and may be updated, replaced, or obsoleted by other documents at any 49 time. It is inappropriate to use Internet-Drafts as reference 50 material or to cite them other than as "work in progress." 52 This Internet-Draft will expire on September 10, 2020. 54 Copyright Notice 56 Copyright (c) 2020 IETF Trust and the persons identified as the 57 document authors. All rights reserved. 59 This document is subject to BCP 78 and the IETF Trust's Legal 60 Provisions Relating to IETF Documents 61 (https://trustee.ietf.org/license-info) in effect on the date of 62 publication of this document. Please review these documents 63 carefully, as they describe your rights and restrictions with respect 64 to this document. Code Components extracted from this document must 65 include Simplified BSD License text as described in Section 4.e of 66 the Trust Legal Provisions and are provided without warranty as 67 described in the Simplified BSD License. 69 Table of Contents 71 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 72 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 73 3. Path Binding TLV . . . . . . . . . . . . . . . . . . . . . . 6 74 4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 7 75 5. Binding SID in SR-ERO . . . . . . . . . . . . . . . . . . . . 8 76 6. Binding SID in SRv6-ERO . . . . . . . . . . . . . . . . . . . 8 77 7. Implementation Status . . . . . . . . . . . . . . . . . . . . 9 78 7.1. Huawei . . . . . . . . . . . . . . . . . . . . . . . . . 9 79 8. Security Considerations . . . . . . . . . . . . . . . . . . . 9 80 9. Manageability Considerations . . . . . . . . . . . . . . . . 10 81 9.1. Control of Function and Policy . . . . . . . . . . . . . 10 82 9.2. Information and Data Models . . . . . . . . . . . . . . . 10 83 9.3. Liveness Detection and Monitoring . . . . . . . . . . . . 10 84 9.4. Verify Correct Operations . . . . . . . . . . . . . . . . 10 85 9.5. Requirements On Other Protocols . . . . . . . . . . . . . 10 86 9.6. Impact On Network Operations . . . . . . . . . . . . . . 11 87 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 88 10.1. PCEP TLV Type Indicators . . . . . . . . . . . . . . . . 11 89 10.1.1. TE-PATH-BINDING TLV . . . . . . . . . . . . . . . . 11 90 10.2. PCEP Error Type and Value . . . . . . . . . . . . . . . 11 91 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12 92 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 93 12.1. Normative References . . . . . . . . . . . . . . . . . . 12 94 12.2. Informative References . . . . . . . . . . . . . . . . . 13 95 Appendix A. Contributor Addresses . . . . . . . . . . . . . . . 15 96 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 98 1. Introduction 100 A PCE can compute Traffic Engineering paths (TE paths) through a 101 network that are subject to various constraints. Currently, TE paths 102 are either set up using the RSVP-TE signaling protocol or Segment 103 Routing (SR). We refer to such paths as RSVP-TE paths and SR-TE 104 paths respectively in this document. 106 As per [RFC8402] SR allows a headend node to steer a packet flow 107 along any path. The headend node is said to steer a flow into an 108 Segment Routing Policy (SR Policy). Further, as per 109 [I-D.ietf-spring-segment-routing-policy], an SR Policy is a framework 110 that enables instantiation of an ordered list of segments on a node 111 for implementing a source routing policy with a specific intent for 112 traffic steering from that node. 114 As described in [RFC8402], Binding Segment Identifier (BSID) is bound 115 to an Segment Routed (SR) Policy, instantiation of which may involve 116 a list of SIDs. Any packets received with an active segment equal to 117 BSID are steered onto the bound SR Policy. A BSID may be either a 118 local (SR Local Block (SRLB)) or a global (SR Global Block (SRGB)) 119 SID. As per Section 6.4 of [I-D.ietf-spring-segment-routing-policy] 120 a BSID can also be associated with any type of interfaces or tunnel 121 to enable the use of a non-SR interface or tunnels as segments in a 122 SID-list. 124 [RFC5440] describes the Path Computation Element Protocol (PCEP) for 125 communication between a Path Computation Client (PCC) and a PCE or 126 between a pair of PCEs as per [RFC4655]. [RFC8231] specifies 127 extension to PCEP that allows a PCC to delegate its LSPs to a 128 stateful PCE. A stateful PCE can then update the state of LSPs 129 delegated to it. [RFC8281] specifies a mechanism allowing a PCE to 130 dynamically instantiate an LSP on a PCC by sending the path and 131 characteristics. The PCEP extension to setup and maintain SR-TE 132 paths is specified in [RFC8664]. 134 [RFC8664] provides a mechanism for a network controller (acting as a 135 PCE) to instantiate candidate paths for an SR Policy onto a head-end 136 node (acting as a PCC) using PCEP. For more information on the SR 137 Policy Architecture, see [I-D.ietf-spring-segment-routing-policy]. 139 Binding label/SID has local significance to the ingress node of the 140 corresponding TE path. When a stateful PCE is deployed for setting 141 up TE paths, it may be desirable to report the binding label or SID 142 to the stateful PCE for the purpose of enforcing end-to-end TE/SR 143 policy. A sample Data Center (DC) use-case is illustrated in the 144 following diagram. In the MPLS DC network, an SR LSP (without 145 traffic engineering) is established using a prefix SID advertised by 146 BGP (see [RFC8669]). In IP/MPLS WAN, an SR-TE LSP is setup using the 147 PCE. The list of SIDs of the SR-TE LSP is {A, B, C, D}. The gateway 148 node 1 (which is the PCC) allocates a binding SID X and reports it to 149 the PCE. In order for the access node to steer the traffic over the 150 SR-TE LSP, the PCE passes the SID stack {Y, X} where Y is the prefix 151 SID of the gateway node-1 to the access node. In the absence of the 152 binding SID X, the PCE should pass the SID stack {Y, A, B, C, D} to 153 the access node. This example also illustrates the additional 154 benefit of using the binding SID to reduce the number of SIDs imposed 155 on the access nodes with a limited forwarding capacity. 157 SID stack 158 {Y, X} +-----+ 159 _ _ _ _ _ _ _ _ _ _ _ _ _ _| PCE | 160 | +-----+ 161 | ^ 162 | | Binding 163 | .-----. | SID (X) .-----. 164 | ( ) | ( ) 165 V .--( )--. | .--( )--. 166 +------+ ( ) +-------+ ( ) +-------+ 167 |Access|_( MPLS DC Network )_|Gateway|_( IP/MPLS WAN )_|Gateway| 168 | Node | ( ==============> ) |Node-1 | ( ================> ) |Node-2 | 169 +------+ ( SR path ) +-------+ ( SR-TE path ) +-------+ 170 '--( )--' Prefix '--( )--' 171 ( ) SID of ( ) 172 '-----' Node-1 '-----' 173 is Y SIDs for SR-TE LSP: 174 {A, B, C, D} 176 Figure 1: A sample Use-case of Binding SID 178 A PCC could report the binding label/SID allocated by it to the 179 stateful PCE via Path Computation State Report (PCRpt) message. It 180 is also possible for a stateful PCE to request a PCC to allocate a 181 specific binding label/SID by sending an Path Computation Update 182 Request (PCUpd) message. If the PCC can successfully allocate the 183 specified binding value, it reports the binding value to the PCE. 184 Otherwise, the PCC sends an error message to the PCE indicating the 185 cause of the failure. A local policy or configuration at the PCC 186 SHOULD dictate if the binding label/SID needs to be assigned. 188 In this document, we introduce a new OPTIONAL TLV that a PCC can use 189 in order to report the binding label/SID associated with a TE LSP, or 190 a PCE to request a PCC to allocate a specific binding label/SID 191 value. This TLV is intended for TE LSPs established using RSVP-TE, 192 SR, or any other future method. Also, in the case of SR-TE LSPs, the 193 TLV can carry a binding MPLS label (for SR-TE path with MPLS data- 194 plane) or a binding IPv6 SID (e.g., IPv6 address for SR-TE paths with 195 IPv6 data-plane). Binding value means either MPLS label or SID 196 throughout this document. 198 Additionally, to support the PCE based central controller [RFC8283] 199 operation where the PCE would take responsibility for managing some 200 part of the MPLS label space for each of the routers that it 201 controls, the PCE could directly make the binding label/SID 202 allocation and inform the PCC. See 203 [I-D.ietf-pce-pcep-extension-for-pce-controller] for details. 205 2. Terminology 207 The following terminologies are used in this document: 209 BSID: Binding Segment Identifier. 211 LER: Label Edge Router. 213 LSP: Label Switched Path. 215 LSR: Label Switching Router. 217 PCC: Path Computation Client. 219 PCE: Path Computation Element 221 PCEP: Path Computation Element Protocol. 223 RSVP-TE: Resource ReserVation Protocol-Traffic Engineering. 225 SID: Segment Identifier. 227 SR: Segment Routing. 229 SRGB: Segment Routing Global Block. 231 SRLB: Segment Routing Local Block. 233 TLV: Type, Length, and Value. 235 3. Path Binding TLV 237 The new optional TLV is called "TE-PATH-BINDING TLV" (whose format is 238 shown in the figure below) is defined to carry binding label or SID 239 for a TE path. This TLV is associated with the LSP object specified 240 in ([RFC8231]). The type of this TLV is to be allocated by IANA. 242 0 1 2 3 243 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 1 244 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 245 | Type | Length | 246 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 247 | BT | Reserved | 248 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 249 ~ Binding Value (variable length) ~ 250 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 252 Figure 2: TE-PATH-BINDING TLV 254 TE-PATH-BINDING TLV is a generic TLV such that it is able to carry 255 MPLS label binding as well as SRv6 Binding SID. It is formatted 256 according to the rules specified in [RFC5440]. 258 Binding Type (BT): A one byte field identifies the type of binding 259 included in the TLV. This document specifies the following BT 260 values: 262 o BT = 0: The binding value is an MPLS label carried in the format 263 specified in [RFC5462] where only the label value is valid, and 264 other fields (TC, S, and TTL) fields MUST be considered invalid. 265 The Length MUST be set to 7. 267 o BT = 1: Similar to the case where BT is 0 except that all the 268 fields on the MPLS label entry are set on transmission. However, 269 the receiver MAY choose to override TC, S, and TTL values 270 according its local policy. The Length MUST be set to 8. 272 o BT = 2: The binding value is a SRv6 SID with a format of an 16 273 byte IPv6 address, representing the binding SID for SRv6. The 274 Length MUST be set to 20. 276 Reserved: MUST be set to 0 while sending and ignored on receipt. 278 Binding Value: A variable length field, padded with trailing zeros to 279 a 4-byte boundary. For the BT as 0, the 20 bits represents the MPLS 280 label. For the BT as 1, the 32-bits represents the label stack entry 281 as per [RFC5462]. For the BT as 2, the 128-bits represent the SRv6 282 SID. 284 4. Operation 286 The binding value is allocated by the PCC and reported to a PCE via 287 PCRpt message. If a PCE does not recognize the TE-PATH-BINDING TLV, 288 it would ignore the TLV in accordance with ([RFC5440]). If a PCE 289 recognizes the TLV but does not support the TLV, it MUST send PCErr 290 with Error-Type = 2 (Capability not supported). 292 If a TE-PATH-BINDING TLV is absent in PCRpt message, PCE MUST assume 293 that the corresponding LSP does not have any binding. If there are 294 more than one TE-PATH-BINDING TLVs, only the first TLV MUST be 295 processed and the rest MUST be silently ignored. If a PCE recognizes 296 an invalid binding value (e.g., label value from the reserved label 297 space when MPLS label binding is used), it MUST send the PCErr 298 message with Error-Type = 10 ("Reception of an invalid object") and 299 Error Value = 2 ("Bad label value") as specified in [RFC8664]. 301 If a PCE requires a PCC to allocate a specific binding value, it may 302 do so by sending a PCUpd or PCInitiate message containing a TE-PATH- 303 BINDING TLV. If the value can be successfully allocated, the PCC 304 reports the binding value to the PCE. If the PCC considers the 305 binding value specified by the PCE invalid, it MUST send a PCErr 306 message with Error-Type = TBD2 ("Binding label/SID failure") and 307 Error Value = TBD3 ("Invalid SID"). If the binding value is valid, 308 but the PCC is unable to allocate the binding value, it MUST send a 309 PCErr message with Error-Type = TBD2 ("Binding label/SID failure") 310 and Error Value = TBD4 ("Unable to allocate the specified label/ 311 SID"). 313 If a PCC receives TE-PATH-BINDING TLV in any message other than PCUpd 314 or PCInitiate, it MUST close the corresponding PCEP session with the 315 reason "Reception of a malformed PCEP message" (according to 316 [RFC5440]). Similarly, if a PCE receives a TE-PATH-BINDING TLV in 317 any message other than a PCRpt or if the TE-PATH-BINDING TLV is 318 associated with any object other than LSP object, the PCE MUST close 319 the corresponding PCEP session with the reason "Reception of a 320 malformed PCEP message" (according to [RFC5440]). 322 If a PCC wishes to withdraw or modify a previously reported binding 323 value, it MUST send a PCRpt message without any TE-PATH-BINDING TLV 324 or with the TE-PATH-BINDING TLV containing the new binding value 325 respectively. 327 If a PCE wishes to modify a previously requested binding value, it 328 MUST send a PCUpd message with TE-PATH-BINDING TLV containing the new 329 binding value. Absence of TE-PATH-BINDING TLV in PCUpd message means 330 that the PCE does not specify a binding value in which case the 331 binding value allocation is governed by the PCC's local policy. 333 If a PCC receives a valid binding value from a PCE which is different 334 than the current binding value, it MUST try to allocate the new 335 value. If the new binding value is successfully allocated, the PCC 336 MUST report the new value to the PCE. Otherwise, it MUST send a 337 PCErr message with Error-Type = TBD2 ("Binding label/SID failure") 338 and Error Value = TBD4 ("Unable to allocate the specified label/ 339 SID"). 341 In some cases, a stateful PCE can request the PCC to allocate a 342 binding value. It may do so by sending a PCUpd message containing an 343 empty TE-PATH-BINDING TLV, i.e., no binding value is specified 344 (making the length field of the TLV as 2). A PCE can also make the 345 request PCC to allocate a binding at the time of initiation by 346 sending a PCInitiate message with an empty TE-PATH-BINDING TLV. 348 5. Binding SID in SR-ERO 350 In PCEP messages, LSP route information is carried in the Explicit 351 Route Object (ERO), which consists of a sequence of subobjects. 352 [RFC8664] defines a new ERO subobject "SR-ERO subobject" capable of 353 carrying a SID as well as the identity of the node/adjacency (NAI) 354 represented by the SID. The NAI Type (NT) field indicates the type 355 and format of the NAI contained in the SR-ERO. In case of binding 356 SID, the NAI MUST NOT be included and NT MUST be set to zero. So as 357 per Section 5.2.1 of [RFC8664], for NT=0, the F bit is set to 1, the 358 S bit needs to be zero and the Length is 8. Further the M bit is 359 set. If these conditions are not met, the entire ERO MUST be 360 considered invalid and a PCErr message is sent with Error-Type = 10 361 ("Reception of an invalid object") and Error-Value = 11 ("Malformed 362 object"). 364 6. Binding SID in SRv6-ERO 366 [RFC8664] defines a new ERO subobject "SRv6-ERO subobject" for SRv6 367 SID. The NAI MUST NOT be included and NT MUST be set to zero. So as 368 per Section 5.2.1 of [RFC8664], for NT=0, the F bit is set to 1, the 369 S bit needs to be zero and the Length is 24. If these conditions are 370 not met, the entire ERO is considered invalid and a PCErr message is 371 sent with Error-Type = 10 ("Reception of an invalid object") and 372 Error-Value = 11 ("Malformed object") (as per [RFC8664]). 374 7. Implementation Status 376 [Note to the RFC Editor - remove this section before publication, as 377 well as remove the reference to RFC 7942.] 379 This section records the status of known implementations of the 380 protocol defined by this specification at the time of posting of this 381 Internet-Draft, and is based on a proposal described in [RFC7942]. 382 The description of implementations in this section is intended to 383 assist the IETF in its decision processes in progressing drafts to 384 RFCs. Please note that the listing of any individual implementation 385 here does not imply endorsement by the IETF. Furthermore, no effort 386 has been spent to verify the information presented here that was 387 supplied by IETF contributors. This is not intended as, and must not 388 be construed to be, a catalog of available implementations or their 389 features. Readers are advised to note that other implementations may 390 exist. 392 According to [RFC7942], "this will allow reviewers and working groups 393 to assign due consideration to documents that have the benefit of 394 running code, which may serve as evidence of valuable experimentation 395 and feedback that have made the implemented protocols more mature. 396 It is up to the individual working groups to use this information as 397 they see fit". 399 7.1. Huawei 401 o Organization: Huawei 403 o Implementation: Huawei's Router and Controller 405 o Description: An experimental code-point is used and plan to 406 request early code-point allocation from IANA after WG adoption. 408 o Maturity Level: Production 410 o Coverage: Full 412 o Contact: chengli13@huawei.com 414 8. Security Considerations 416 The security considerations described in [RFC5440], [RFC8231], 417 [RFC8281] and [RFC8664] are applicable to this specification. No 418 additional security measure is required. 420 As described [RFC8664], SR allows a network controller to instantiate 421 and control paths in the network. A rouge PCE can manipulate binding 422 SID allocations to move traffic around for some other LSPs that uses 423 BSID in its SR-ERO. 425 Thus, as per [RFC8231], it is RECOMMENDED that these PCEP extensions 426 only be activated on authenticated and encrypted sessions across PCEs 427 and PCCs belonging to the same administrative authority, using 428 Transport Layer Security (TLS) [RFC8253], as per the recommendations 429 and best current practices in BCP195 [RFC7525] (unless explicitly set 430 aside in [RFC8253]). 432 9. Manageability Considerations 434 All manageability requirements and considerations listed in 435 [RFC5440], [RFC8231], and [RFC8664] apply to PCEP protocol extensions 436 defined in this document. In addition, requirements and 437 considerations listed in this section apply. 439 9.1. Control of Function and Policy 441 A PCC implementation SHOULD allow the operator to configure the 442 policy based on which PCC needs to allocates the binding label/SID. 444 9.2. Information and Data Models 446 The PCEP YANG module [I-D.ietf-pce-pcep-yang] could be extended to 447 include policy configuration for binding label/SID allocation. 449 9.3. Liveness Detection and Monitoring 451 Mechanisms defined in this document do not imply any new liveness 452 detection and monitoring requirements in addition to those already 453 listed in [RFC5440]. 455 9.4. Verify Correct Operations 457 Mechanisms defined in this document do not imply any new operation 458 verification requirements in addition to those already listed in 459 [RFC5440], [RFC8231], and [RFC8664]. 461 9.5. Requirements On Other Protocols 463 Mechanisms defined in this document do not imply any new requirements 464 on other protocols. 466 9.6. Impact On Network Operations 468 Mechanisms defined in [RFC5440], [RFC8231], and [RFC8664] also apply 469 to PCEP extensions defined in this document. Further, the mechanism 470 described in this document can help the operator to request control 471 of the LSPs at a particular PCE. 473 10. IANA Considerations 475 10.1. PCEP TLV Type Indicators 477 This document defines a new PCEP TLV; IANA is requested to make the 478 following allocations from the "PCEP TLV Type Indicators" sub- 479 registry of the PCEP Numbers registry, as follows: 481 Value Name Reference 483 TBD1 TE-PATH-BINDING This document 485 10.1.1. TE-PATH-BINDING TLV 487 IANA is requested to create a sub-registry to manage the value of the 488 Binding Type field in the TE-PATH-BINDING TLV. 490 Value Description Reference 492 0 MPLS Label This document 493 1 MPLS Label Stack This document 494 Entry 495 2 SRv6 SID This document 497 10.2. PCEP Error Type and Value 499 This document defines a new Error-type and Error-Values for the PCErr 500 message. IANA is requested to allocate new error-type and error- 501 values within the "PCEP-ERROR Object Error Types and Values" 502 subregistry of the PCEP Numbers registry, as follows: 504 Error-Type Meaning 505 ---------- ------- 506 TBD2 Binding label/SID failure: 508 Error-value = TBD3: Invalid SID 509 Error-value = TBD4: Unable to allocate 510 the specified 511 label/SID 513 11. Acknowledgements 515 We like to thank Milos Fabian for his valuable comments. 517 12. References 519 12.1. Normative References 521 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 522 Requirement Levels", BCP 14, RFC 2119, 523 DOI 10.17487/RFC2119, March 1997, 524 . 526 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 527 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 528 DOI 10.17487/RFC5440, March 2009, 529 . 531 [RFC5462] Andersson, L. and R. Asati, "Multiprotocol Label Switching 532 (MPLS) Label Stack Entry: "EXP" Field Renamed to "Traffic 533 Class" Field", RFC 5462, DOI 10.17487/RFC5462, February 534 2009, . 536 [RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre, 537 "Recommendations for Secure Use of Transport Layer 538 Security (TLS) and Datagram Transport Layer Security 539 (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May 540 2015, . 542 [RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running 543 Code: The Implementation Status Section", BCP 205, 544 RFC 7942, DOI 10.17487/RFC7942, July 2016, 545 . 547 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 548 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 549 May 2017, . 551 [RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path 552 Computation Element Communication Protocol (PCEP) 553 Extensions for Stateful PCE", RFC 8231, 554 DOI 10.17487/RFC8231, September 2017, 555 . 557 [RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody, 558 "PCEPS: Usage of TLS to Provide a Secure Transport for the 559 Path Computation Element Communication Protocol (PCEP)", 560 RFC 8253, DOI 10.17487/RFC8253, October 2017, 561 . 563 [RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path 564 Computation Element Communication Protocol (PCEP) 565 Extensions for PCE-Initiated LSP Setup in a Stateful PCE 566 Model", RFC 8281, DOI 10.17487/RFC8281, December 2017, 567 . 569 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 570 Decraene, B., Litkowski, S., and R. Shakir, "Segment 571 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 572 July 2018, . 574 [RFC8664] Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W., 575 and J. Hardwick, "Path Computation Element Communication 576 Protocol (PCEP) Extensions for Segment Routing", RFC 8664, 577 DOI 10.17487/RFC8664, December 2019, 578 . 580 12.2. Informative References 582 [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation 583 Element (PCE)-Based Architecture", RFC 4655, 584 DOI 10.17487/RFC4655, August 2006, 585 . 587 [RFC8283] Farrel, A., Ed., Zhao, Q., Ed., Li, Z., and C. Zhou, "An 588 Architecture for Use of PCE and the PCE Communication 589 Protocol (PCEP) in a Network with Central Control", 590 RFC 8283, DOI 10.17487/RFC8283, December 2017, 591 . 593 [RFC8669] Previdi, S., Filsfils, C., Lindem, A., Ed., Sreekantiah, 594 A., and H. Gredler, "Segment Routing Prefix Segment 595 Identifier Extensions for BGP", RFC 8669, 596 DOI 10.17487/RFC8669, December 2019, 597 . 599 [I-D.ietf-spring-segment-routing-policy] 600 Filsfils, C., Sivabalan, S., Voyer, D., Bogdanov, A., and 601 P. Mattes, "Segment Routing Policy Architecture", draft- 602 ietf-spring-segment-routing-policy-06 (work in progress), 603 December 2019. 605 [I-D.ietf-pce-pcep-extension-for-pce-controller] 606 Zhao, Q., Li, Z., Negi, M., Peng, S., and C. Zhou, "PCEP 607 Procedures and Protocol Extensions for Using PCE as a 608 Central Controller (PCECC) of LSPs", draft-ietf-pce-pcep- 609 extension-for-pce-controller-04 (work in progress), March 610 2020. 612 [I-D.ietf-pce-pcep-yang] 613 Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A 614 YANG Data Model for Path Computation Element 615 Communications Protocol (PCEP)", draft-ietf-pce-pcep- 616 yang-13 (work in progress), October 2019. 618 Appendix A. Contributor Addresses 620 Dhruv Dhody 621 Huawei Technologies 622 Divyashree Techno Park, Whitefield 623 Bangalore, Karnataka 560066 624 India 626 EMail: dhruv.ietf@gmail.com 628 Mahendra Singh Negi 630 EMail: mahend.ietf@gmail.com 632 Authors' Addresses 634 Siva Sivabalan 635 Cisco Systems, Inc. 636 2000 Innovation Drive 637 Kanata, Ontario K2K 3E8 638 Canada 640 EMail: msiva@cisco.com 642 Clarence Filsfils 643 Cisco Systems, Inc. 644 Pegasus Parc 645 De kleetlaan 6a, DIEGEM BRABANT 1831 646 BELGIUM 648 EMail: cfilsfil@cisco.com 650 Jeff Tantsura 651 Apstra, Inc. 653 EMail: jefftant.ietf@gmail.com 655 Jonathan Hardwick 656 Metaswitch Networks 657 100 Church Street 658 Enfield, Middlesex 659 UK 661 EMail: Jonathan.Hardwick@metaswitch.com 662 Stefano Previdi 663 Huawei Technologies 665 EMail: stefano@previdi.net 667 Cheng Li 668 Huawei Technologies 669 Huawei Campus, No. 156 Beiqing Rd. 670 Beijing 100095 671 China 673 EMail: chengli13@huawei.com