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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references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 7525 (Obsoleted by RFC 9325) == Outdated reference: A later version (-28) exists of draft-ietf-spring-srv6-network-programming-24 == Outdated reference: A later version (-22) exists of draft-ietf-spring-segment-routing-policy-08 == Outdated reference: A later version (-14) exists of draft-ietf-pce-pcep-extension-for-pce-controller-07 == Outdated reference: A later version (-23) exists of draft-ietf-pce-pcep-yang-14 Summary: 1 error (**), 0 flaws (~~), 5 warnings (==), 1 comment (--).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 Ciena Corporation 4 Intended status: Standards Track C. Filsfils 5 Expires: May 4, 2021 Cisco Systems, Inc. 6 J. Tantsura 7 Apstra, Inc. 8 J. Hardwick 9 Metaswitch Networks 10 S. Previdi 11 C. Li 12 Huawei Technologies 13 October 31, 2020 15 Carrying Binding Label/Segment-ID in PCE-based Networks. 16 draft-ietf-pce-binding-label-sid-04 18 Abstract 20 In order to provide greater scalability, network opacity, and service 21 independence, Segment Routing (SR) utilizes a Binding Segment 22 Identifier (BSID). It is possible to associate a BSID to RSVP-TE 23 signaled Traffic Engineering Label Switching Path or binding Segment- 24 ID (SID) to SR Traffic Engineering path. Such a binding label/SID 25 can be used by an upstream node for steering traffic into the 26 appropriate TE path to enforce SR policies. This document proposes 27 an approach for reporting binding label/SID to Path Computation 28 Element (PCE) for supporting PCE-based Traffic Engineering policies. 30 Requirements Language 32 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 33 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 34 "OPTIONAL" in this document are to be interpreted as described in BCP 35 14 [RFC2119] [RFC8174] when, and only when, they appear in all 36 capitals, as shown here. 38 Status of This Memo 40 This Internet-Draft is submitted in full conformance with the 41 provisions of BCP 78 and BCP 79. 43 Internet-Drafts are working documents of the Internet Engineering 44 Task Force (IETF). Note that other groups may also distribute 45 working documents as Internet-Drafts. The list of current Internet- 46 Drafts is at https://datatracker.ietf.org/drafts/current/. 48 Internet-Drafts are draft documents valid for a maximum of six months 49 and may be updated, replaced, or obsoleted by other documents at any 50 time. It is inappropriate to use Internet-Drafts as reference 51 material or to cite them other than as "work in progress." 53 This Internet-Draft will expire on May 4, 2021. 55 Copyright Notice 57 Copyright (c) 2020 IETF Trust and the persons identified as the 58 document authors. All rights reserved. 60 This document is subject to BCP 78 and the IETF Trust's Legal 61 Provisions Relating to IETF Documents 62 (https://trustee.ietf.org/license-info) in effect on the date of 63 publication of this document. Please review these documents 64 carefully, as they describe your rights and restrictions with respect 65 to this document. Code Components extracted from this document must 66 include Simplified BSD License text as described in Section 4.e of 67 the Trust Legal Provisions and are provided without warranty as 68 described in the Simplified BSD License. 70 Table of Contents 72 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 73 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 74 3. Path Binding TLV . . . . . . . . . . . . . . . . . . . . . . 6 75 4. SRv6 Endpoint Behavior and SID Structure . . . . . . . . . . 7 76 5. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 8 77 6. Binding SID in SR-ERO . . . . . . . . . . . . . . . . . . . . 9 78 7. Binding SID in SRv6-ERO . . . . . . . . . . . . . . . . . . . 10 79 8. Implementation Status . . . . . . . . . . . . . . . . . . . . 10 80 8.1. Huawei . . . . . . . . . . . . . . . . . . . . . . . . . 10 81 9. Security Considerations . . . . . . . . . . . . . . . . . . . 11 82 10. Manageability Considerations . . . . . . . . . . . . . . . . 11 83 10.1. Control of Function and Policy . . . . . . . . . . . . . 11 84 10.2. Information and Data Models . . . . . . . . . . . . . . 11 85 10.3. Liveness Detection and Monitoring . . . . . . . . . . . 12 86 10.4. Verify Correct Operations . . . . . . . . . . . . . . . 12 87 10.5. Requirements On Other Protocols . . . . . . . . . . . . 12 88 10.6. Impact On Network Operations . . . . . . . . . . . . . . 12 89 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 90 11.1. PCEP TLV Type Indicators . . . . . . . . . . . . . . . . 12 91 11.1.1. TE-PATH-BINDING TLV . . . . . . . . . . . . . . . . 12 92 11.1.2. Binding SID Flags . . . . . . . . . . . . . . . . . 13 93 11.2. PCEP Error Type and Value . . . . . . . . . . . . . . . 13 94 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13 95 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 96 13.1. Normative References . . . . . . . . . . . . . . . . . . 13 97 13.2. Informative References . . . . . . . . . . . . . . . . . 15 98 Appendix A. Contributor Addresses . . . . . . . . . . . . . . . 16 99 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 101 1. Introduction 103 A PCE can compute Traffic Engineering paths (TE paths) through a 104 network that are subject to various constraints. Currently, TE paths 105 are either set up using the RSVP-TE signaling protocol or Segment 106 Routing (SR). We refer to such paths as RSVP-TE paths and SR-TE 107 paths respectively in this document. 109 As per [RFC8402] SR allows a headend node to steer a packet flow 110 along any path. The headend node is said to steer a flow into an 111 Segment Routing Policy (SR Policy). Further, as per 112 [I-D.ietf-spring-segment-routing-policy], an SR Policy is a framework 113 that enables instantiation of an ordered list of segments on a node 114 for implementing a source routing policy with a specific intent for 115 traffic steering from that node. 117 As described in [RFC8402], Binding Segment Identifier (BSID) is bound 118 to an Segment Routed (SR) Policy, instantiation of which may involve 119 a list of SIDs. Any packets received with an active segment equal to 120 BSID are steered onto the bound SR Policy. A BSID may be either a 121 local (SR Local Block (SRLB)) or a global (SR Global Block (SRGB)) 122 SID. As per Section 6.4 of [I-D.ietf-spring-segment-routing-policy] 123 a BSID can also be associated with any type of interfaces or tunnel 124 to enable the use of a non-SR interface or tunnels as segments in a 125 SID-list. 127 [RFC5440] describes the Path Computation Element Protocol (PCEP) for 128 communication between a Path Computation Client (PCC) and a PCE or 129 between a pair of PCEs as per [RFC4655]. [RFC8231] specifies 130 extension to PCEP that allows a PCC to delegate its LSPs to a 131 stateful PCE. A stateful PCE can then update the state of LSPs 132 delegated to it. [RFC8281] specifies a mechanism allowing a PCE to 133 dynamically instantiate an LSP on a PCC by sending the path and 134 characteristics. The PCEP extension to setup and maintain SR-TE 135 paths is specified in [RFC8664]. 137 [RFC8664] provides a mechanism for a network controller (acting as a 138 PCE) to instantiate candidate paths for an SR Policy onto a head-end 139 node (acting as a PCC) using PCEP. For more information on the SR 140 Policy Architecture, see [I-D.ietf-spring-segment-routing-policy]. 142 Binding label/SID has local significance to the ingress node of the 143 corresponding TE path. When a stateful PCE is deployed for setting 144 up TE paths, it may be desirable to report the binding label or SID 145 to the stateful PCE for the purpose of enforcing end-to-end TE/SR 146 policy. A sample Data Center (DC) use-case is illustrated in the 147 following diagram. In the MPLS DC network, an SR LSP (without 148 traffic engineering) is established using a prefix SID advertised by 149 BGP (see [RFC8669]). In IP/MPLS WAN, an SR-TE LSP is setup using the 150 PCE. The list of SIDs of the SR-TE LSP is {A, B, C, D}. The gateway 151 node 1 (which is the PCC) allocates a binding SID X and reports it to 152 the PCE. In order for the access node to steer the traffic over the 153 SR-TE LSP, the PCE passes the SID stack {Y, X} where Y is the prefix 154 SID of the gateway node-1 to the access node. In the absence of the 155 binding SID X, the PCE should pass the SID stack {Y, A, B, C, D} to 156 the access node. This example also illustrates the additional 157 benefit of using the binding SID to reduce the number of SIDs imposed 158 on the access nodes with a limited forwarding capacity. 160 SID stack 161 {Y, X} +-----+ 162 _ _ _ _ _ _ _ _ _ _ _ _ _ _| PCE | 163 | +-----+ 164 | ^ 165 | | Binding 166 | .-----. | SID (X) .-----. 167 | ( ) | ( ) 168 V .--( )--. | .--( )--. 169 +------+ ( ) +-------+ ( ) +-------+ 170 |Access|_( MPLS DC Network )_|Gateway|_( IP/MPLS WAN )_|Gateway| 171 | Node | ( ==============> ) |Node-1 | ( ================> ) |Node-2 | 172 +------+ ( SR path ) +-------+ ( SR-TE path ) +-------+ 173 '--( )--' Prefix '--( )--' 174 ( ) SID of ( ) 175 '-----' Node-1 '-----' 176 is Y SIDs for SR-TE LSP: 177 {A, B, C, D} 179 Figure 1: A sample Use-case of Binding SID 181 A PCC could report the binding label/SID allocated by it to the 182 stateful PCE via Path Computation State Report (PCRpt) message. It 183 is also possible for a stateful PCE to request a PCC to allocate a 184 specific binding label/SID by sending an Path Computation Update 185 Request (PCUpd) message. If the PCC can successfully allocate the 186 specified binding value, it reports the binding value to the PCE. 187 Otherwise, the PCC sends an error message to the PCE indicating the 188 cause of the failure. A local policy or configuration at the PCC 189 SHOULD dictate if the binding label/SID needs to be assigned. 191 In this document, we introduce a new OPTIONAL TLV that a PCC can use 192 in order to report the binding label/SID associated with a TE LSP, or 193 a PCE to request a PCC to allocate a specific binding label/SID 194 value. This TLV is intended for TE LSPs established using RSVP-TE, 195 SR, or any other future method. Also, in the case of SR-TE LSPs, the 196 TLV can carry a binding MPLS label (for SR-TE path with MPLS data- 197 plane) or a binding IPv6 SID (e.g., IPv6 address for SR-TE paths with 198 IPv6 data-plane). Binding value means either MPLS label or SID 199 throughout this document. 201 Additionally, to support the PCE based central controller [RFC8283] 202 operation where the PCE would take responsibility for managing some 203 part of the MPLS label space for each of the routers that it 204 controls, the PCE could directly make the binding label/SID 205 allocation and inform the PCC. See 206 [I-D.ietf-pce-pcep-extension-for-pce-controller] for details. 208 2. Terminology 210 The following terminologies are used in this document: 212 BSID: Binding Segment Identifier. 214 LER: Label Edge Router. 216 LSP: Label Switched Path. 218 LSR: Label Switching Router. 220 PCC: Path Computation Client. 222 PCE: Path Computation Element 224 PCEP: Path Computation Element Protocol. 226 RSVP-TE: Resource ReserVation Protocol-Traffic Engineering. 228 SID: Segment Identifier. 230 SR: Segment Routing. 232 SRGB: Segment Routing Global Block. 234 SRLB: Segment Routing Local Block. 236 TLV: Type, Length, and Value. 238 3. Path Binding TLV 240 The new optional TLV is called "TE-PATH-BINDING TLV" (whose format is 241 shown in the figure below) is defined to carry binding label or SID 242 for a TE path. This TLV is associated with the LSP object specified 243 in ([RFC8231]). The type of this TLV is to be allocated by IANA. 245 0 1 2 3 246 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 1 247 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 248 | Type | Length | 249 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 250 | BT | Flags | Reserved | 251 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 252 ~ Binding Value (variable length) ~ 253 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 255 Figure 2: TE-PATH-BINDING TLV 257 TE-PATH-BINDING TLV is a generic TLV such that it is able to carry 258 MPLS label binding as well as SRv6 Binding SID. It is formatted 259 according to the rules specified in [RFC5440]. 261 Binding Type (BT): A one byte field identifies the type of binding 262 included in the TLV. This document specifies the following BT 263 values: 265 o BT = 0: The binding value is an MPLS label carried in the format 266 specified in [RFC5462] where only the label value is valid, and 267 other fields fields MUST be considered invalid. The Length MUST 268 be set to 7. 270 o BT = 1: Similar to the case where BT is 0 except that all the 271 fields on the MPLS label entry are set on transmission. However, 272 the receiver MAY choose to override TC, S, and TTL values 273 according its local policy. The Length MUST be set to 8. 275 o BT = 2: The binding value is an SRv6 SID with a format of a 16 276 byte IPv6 address, representing the binding SID for SRv6. The 277 Length MUST be set to 20. 279 o BT = 3: The binding value is a 24 octet field, defined in 280 Section 4, that contains the SRv6 SID as well as its Behavior and 281 Structure. The Length MUST be set to 28. 283 Flags: 1 octet of flags. Following flags are defined in the new 284 registry "SR Policy Binding SID Flags" as described in 285 Section 11.1.2: 287 0 1 2 3 4 5 6 7 288 +-+-+-+-+-+-+-+-+ 289 |S|I| | 290 +-+-+-+-+-+-+-+-+ 292 where: 294 o S-Flag: This flag encodes the "Specified-BSID-only" behavior. It 295 is used as described in Section 6.2.3 of 296 [I-D.ietf-spring-segment-routing-policy]. 298 o I-Flag: This flag encodes the "Drop Upon Invalid" behavior. It is 299 used by described in Section 8.2 of 300 [I-D.ietf-spring-segment-routing-policy]. 302 Reserved: MUST be set to 0 while sending and ignored on receipt. 304 Binding Value: A variable length field, padded with trailing zeros to 305 a 4-byte boundary. For the BT as 0, the 20 bits represent the MPLS 306 label. For the BT as 1, the 32-bits represent the label stack entry 307 as per [RFC5462]. For the BT as 2, the 128-bits represent the SRv6 308 SID. For the BT as 3, the Binding Value contains SRv6 Endpoint 309 Behavior and SID Structure, defined in Section 4. 311 4. SRv6 Endpoint Behavior and SID Structure 313 Carried as the Binding Value in the TE-PATH-BINDING TLV when the BT 314 is set to 3. Applicable for SRv6 Binding SIDs 315 [I-D.ietf-spring-srv6-network-programming]. 317 0 1 2 3 318 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 1 319 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 320 | SRv6 Binding SID (16 octets) | 321 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 322 | Endpoint Behavior | LB Length | LN Length | 323 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 324 | Fun. Length | Arg. Length | Reserved | 325 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 327 Figure 4: SRv6 Endpoint Behavior and SID Structure 329 Endpoint Behavior: 2 octets. The Endpoint Behavior code point for 330 this SRv6 SID as defined in section 9.2 of 331 [I-D.ietf-spring-srv6-network-programming]. When set with the value 332 0, the choice of behavior is considered unset. 334 LB Length: 1 octet. SRv6 SID Locator Block length in bits. 336 LN Length: 1 octet. SRv6 SID Locator Node length in bits. 338 Function Length: 1 octet. SRv6 SID Function length in bits. 340 Argument Length: 1 octet. SRv6 SID Arguments length in bits. 342 5. Operation 344 The binding value is allocated by the PCC and reported to a PCE via 345 PCRpt message. If a PCE does not recognize the TE-PATH-BINDING TLV, 346 it would ignore the TLV in accordance with ([RFC5440]). If a PCE 347 recognizes the TLV but does not support the TLV, it MUST send PCErr 348 with Error-Type = 2 (Capability not supported). 350 If a TE-PATH-BINDING TLV is absent in PCRpt message, PCE MUST assume 351 that the corresponding LSP does not have any binding. If a PCE 352 recognizes an invalid binding value (e.g., label value from the 353 reserved label space when MPLS label binding is used), it MUST send 354 the PCErr message with Error-Type = 10 ("Reception of an invalid 355 object") and Error Value = 2 ("Bad label value") as specified in 356 [RFC8664]. 358 Multiple TE-PATH-BINDING TLVs are allowed to be present in the same 359 LSP object. This signifies the presence of multiple binding SIDs for 360 the given LSP. Either due to multiple SRv6 binding SIDs with 361 different behaviors or due to SRv6 and MPLS binding SIDs being 362 present together. 364 For SRv6 BSIDs, it is RECOMMENDED to always explicitly specify the 365 SRv6 Endpoint Behavior and SID Structure in the TE-PATH-BINDING TLV 366 by setting the BT (Binding Type) to 3, instead of 2. The choice of 367 interpreting SRv6 Endpoint Behavior and SID Structure when none is 368 explicitly specified is left up to the implementation. 370 If a PCE requires a PCC to allocate a specific binding value, it may 371 do so by sending a PCUpd or PCInitiate message containing a TE-PATH- 372 BINDING TLV. If the value can be successfully allocated, the PCC 373 reports the binding value to the PCE. If the PCC considers the 374 binding value specified by the PCE invalid, it MUST send a PCErr 375 message with Error-Type = TBD2 ("Binding label/SID failure") and 376 Error Value = TBD3 ("Invalid SID"). If the binding value is valid, 377 but the PCC is unable to allocate the binding value, it MUST send a 378 PCErr message with Error-Type = TBD2 ("Binding label/SID failure") 379 and Error Value = TBD4 ("Unable to allocate the specified label/ 380 SID"). 382 If a PCC receives TE-PATH-BINDING TLV in any message other than PCUpd 383 or PCInitiate, it MUST close the corresponding PCEP session with the 384 reason "Reception of a malformed PCEP message" (according to 385 [RFC5440]). Similarly, if a PCE receives a TE-PATH-BINDING TLV in 386 any message other than a PCRpt or if the TE-PATH-BINDING TLV is 387 associated with any object other than LSP object, the PCE MUST close 388 the corresponding PCEP session with the reason "Reception of a 389 malformed PCEP message" (according to [RFC5440]). 391 If a PCC wishes to withdraw or modify a previously reported binding 392 value, it MUST send a PCRpt message without any TE-PATH-BINDING TLV 393 or with the TE-PATH-BINDING TLV containing the new binding value 394 respectively. 396 If a PCE wishes to modify a previously requested binding value, it 397 MUST send a PCUpd message with TE-PATH-BINDING TLV containing the new 398 binding value. Absence of TE-PATH-BINDING TLV in PCUpd message means 399 that the PCE does not specify a binding value in which case the 400 binding value allocation is governed by the PCC's local policy. 402 If a PCC receives a valid binding value from a PCE which is different 403 than the current binding value, it MUST try to allocate the new 404 value. If the new binding value is successfully allocated, the PCC 405 MUST report the new value to the PCE. Otherwise, it MUST send a 406 PCErr message with Error-Type = TBD2 ("Binding label/SID failure") 407 and Error Value = TBD4 ("Unable to allocate the specified label/ 408 SID"). 410 In some cases, a stateful PCE can request the PCC to allocate a 411 binding value. It may do so by sending a PCUpd message containing an 412 empty TE-PATH-BINDING TLV, i.e., no binding value is specified 413 (making the length field of the TLV as 4). A PCE can also make the 414 request PCC to allocate a binding at the time of initiation by 415 sending a PCInitiate message with an empty TE-PATH-BINDING TLV. 417 6. Binding SID in SR-ERO 419 In PCEP messages, LSP route information is carried in the Explicit 420 Route Object (ERO), which consists of a sequence of subobjects. 421 [RFC8664] defines a new ERO subobject "SR-ERO subobject" capable of 422 carrying a SID as well as the identity of the node/adjacency (NAI) 423 represented by the SID. The NAI Type (NT) field indicates the type 424 and format of the NAI contained in the SR-ERO. In case of binding 425 SID, the NAI MUST NOT be included and NT MUST be set to zero. So as 426 per Section 5.2.1 of [RFC8664], for NT=0, the F bit is set to 1, the 427 S bit needs to be zero and the Length is 8. Further the M bit is 428 set. If these conditions are not met, the entire ERO MUST be 429 considered invalid and a PCErr message is sent with Error-Type = 10 430 ("Reception of an invalid object") and Error-Value = 11 ("Malformed 431 object"). 433 7. Binding SID in SRv6-ERO 435 [RFC8664] defines a new ERO subobject "SRv6-ERO subobject" for SRv6 436 SID. The NAI MUST NOT be included and NT MUST be set to zero. So as 437 per Section 5.2.1 of [RFC8664], for NT=0, the F bit is set to 1, the 438 S bit needs to be zero and the Length is 24. If these conditions are 439 not met, the entire ERO is considered invalid and a PCErr message is 440 sent with Error-Type = 10 ("Reception of an invalid object") and 441 Error-Value = 11 ("Malformed object") (as per [RFC8664]). 443 8. Implementation Status 445 [Note to the RFC Editor - remove this section before publication, as 446 well as remove the reference to RFC 7942.] 448 This section records the status of known implementations of the 449 protocol defined by this specification at the time of posting of this 450 Internet-Draft, and is based on a proposal described in [RFC7942]. 451 The description of implementations in this section is intended to 452 assist the IETF in its decision processes in progressing drafts to 453 RFCs. Please note that the listing of any individual implementation 454 here does not imply endorsement by the IETF. Furthermore, no effort 455 has been spent to verify the information presented here that was 456 supplied by IETF contributors. This is not intended as, and must not 457 be construed to be, a catalog of available implementations or their 458 features. Readers are advised to note that other implementations may 459 exist. 461 According to [RFC7942], "this will allow reviewers and working groups 462 to assign due consideration to documents that have the benefit of 463 running code, which may serve as evidence of valuable experimentation 464 and feedback that have made the implemented protocols more mature. 465 It is up to the individual working groups to use this information as 466 they see fit". 468 8.1. Huawei 470 o Organization: Huawei 472 o Implementation: Huawei's Router and Controller 473 o Description: An experimental code-point is used and plan to 474 request early code-point allocation from IANA after WG adoption. 476 o Maturity Level: Production 478 o Coverage: Full 480 o Contact: chengli13@huawei.com 482 9. Security Considerations 484 The security considerations described in [RFC5440], [RFC8231], 485 [RFC8281] and [RFC8664] are applicable to this specification. No 486 additional security measure is required. 488 As described [RFC8664], SR allows a network controller to instantiate 489 and control paths in the network. A rouge PCE can manipulate binding 490 SID allocations to move traffic around for some other LSPs that uses 491 BSID in its SR-ERO. 493 Thus, as per [RFC8231], it is RECOMMENDED that these PCEP extensions 494 only be activated on authenticated and encrypted sessions across PCEs 495 and PCCs belonging to the same administrative authority, using 496 Transport Layer Security (TLS) [RFC8253], as per the recommendations 497 and best current practices in BCP195 [RFC7525] (unless explicitly set 498 aside in [RFC8253]). 500 10. Manageability Considerations 502 All manageability requirements and considerations listed in 503 [RFC5440], [RFC8231], and [RFC8664] apply to PCEP protocol extensions 504 defined in this document. In addition, requirements and 505 considerations listed in this section apply. 507 10.1. Control of Function and Policy 509 A PCC implementation SHOULD allow the operator to configure the 510 policy based on which PCC needs to allocates the binding label/SID. 512 10.2. Information and Data Models 514 The PCEP YANG module [I-D.ietf-pce-pcep-yang] could be extended to 515 include policy configuration for binding label/SID allocation. 517 10.3. Liveness Detection and Monitoring 519 Mechanisms defined in this document do not imply any new liveness 520 detection and monitoring requirements in addition to those already 521 listed in [RFC5440]. 523 10.4. Verify Correct Operations 525 Mechanisms defined in this document do not imply any new operation 526 verification requirements in addition to those already listed in 527 [RFC5440], [RFC8231], and [RFC8664]. 529 10.5. Requirements On Other Protocols 531 Mechanisms defined in this document do not imply any new requirements 532 on other protocols. 534 10.6. Impact On Network Operations 536 Mechanisms defined in [RFC5440], [RFC8231], and [RFC8664] also apply 537 to PCEP extensions defined in this document. Further, the mechanism 538 described in this document can help the operator to request control 539 of the LSPs at a particular PCE. 541 11. IANA Considerations 543 11.1. PCEP TLV Type Indicators 545 This document defines a new PCEP TLV; IANA is requested to make the 546 following allocations from the "PCEP TLV Type Indicators" sub- 547 registry of the PCEP Numbers registry, as follows: 549 Value Name Reference 551 TBD1 TE-PATH-BINDING This document 553 11.1.1. TE-PATH-BINDING TLV 555 IANA is requested to create a sub-registry to manage the value of the 556 Binding Type field in the TE-PATH-BINDING TLV. 558 Value Description Reference 560 0 MPLS Label This document 561 1 MPLS Label Stack This document 562 Entry 563 2 SRv6 SID This document 565 11.1.2. Binding SID Flags 567 IANA is requested to create a sub-registry to manage the value of the 568 Binding SID Flags field in the TE-PATH-BINDING-TLV. 570 Bit Description Reference 572 0 Specified-BSID-Only This document 573 Flag (S-Flag) 574 1 Drop Upon Invalid This document 575 Flag (I-Flag) 577 11.2. PCEP Error Type and Value 579 This document defines a new Error-type and Error-Values for the PCErr 580 message. IANA is requested to allocate new error-type and error- 581 values within the "PCEP-ERROR Object Error Types and Values" 582 subregistry of the PCEP Numbers registry, as follows: 584 Error-Type Meaning 585 ---------- ------- 586 TBD2 Binding label/SID failure: 588 Error-value = TBD3: Invalid SID 589 Error-value = TBD4: Unable to allocate 590 the specified 591 label/SID 593 12. Acknowledgements 595 We like to thank Milos Fabian and Mrinmoy Das for thier valuable 596 comments. 598 13. References 600 13.1. Normative References 602 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 603 Requirement Levels", BCP 14, RFC 2119, 604 DOI 10.17487/RFC2119, March 1997, 605 . 607 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 608 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 609 DOI 10.17487/RFC5440, March 2009, 610 . 612 [RFC5462] Andersson, L. and R. Asati, "Multiprotocol Label Switching 613 (MPLS) Label Stack Entry: "EXP" Field Renamed to "Traffic 614 Class" Field", RFC 5462, DOI 10.17487/RFC5462, February 615 2009, . 617 [RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre, 618 "Recommendations for Secure Use of Transport Layer 619 Security (TLS) and Datagram Transport Layer Security 620 (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May 621 2015, . 623 [RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running 624 Code: The Implementation Status Section", BCP 205, 625 RFC 7942, DOI 10.17487/RFC7942, July 2016, 626 . 628 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 629 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 630 May 2017, . 632 [RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path 633 Computation Element Communication Protocol (PCEP) 634 Extensions for Stateful PCE", RFC 8231, 635 DOI 10.17487/RFC8231, September 2017, 636 . 638 [RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody, 639 "PCEPS: Usage of TLS to Provide a Secure Transport for the 640 Path Computation Element Communication Protocol (PCEP)", 641 RFC 8253, DOI 10.17487/RFC8253, October 2017, 642 . 644 [RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path 645 Computation Element Communication Protocol (PCEP) 646 Extensions for PCE-Initiated LSP Setup in a Stateful PCE 647 Model", RFC 8281, DOI 10.17487/RFC8281, December 2017, 648 . 650 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 651 Decraene, B., Litkowski, S., and R. Shakir, "Segment 652 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 653 July 2018, . 655 [RFC8664] Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W., 656 and J. Hardwick, "Path Computation Element Communication 657 Protocol (PCEP) Extensions for Segment Routing", RFC 8664, 658 DOI 10.17487/RFC8664, December 2019, 659 . 661 [I-D.ietf-spring-srv6-network-programming] 662 Filsfils, C., Camarillo, P., Leddy, J., Voyer, D., 663 Matsushima, S., and Z. Li, "SRv6 Network Programming", 664 draft-ietf-spring-srv6-network-programming-24 (work in 665 progress), October 2020. 667 13.2. Informative References 669 [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation 670 Element (PCE)-Based Architecture", RFC 4655, 671 DOI 10.17487/RFC4655, August 2006, 672 . 674 [RFC8283] Farrel, A., Ed., Zhao, Q., Ed., Li, Z., and C. Zhou, "An 675 Architecture for Use of PCE and the PCE Communication 676 Protocol (PCEP) in a Network with Central Control", 677 RFC 8283, DOI 10.17487/RFC8283, December 2017, 678 . 680 [RFC8669] Previdi, S., Filsfils, C., Lindem, A., Ed., Sreekantiah, 681 A., and H. Gredler, "Segment Routing Prefix Segment 682 Identifier Extensions for BGP", RFC 8669, 683 DOI 10.17487/RFC8669, December 2019, 684 . 686 [I-D.ietf-spring-segment-routing-policy] 687 Filsfils, C., Talaulikar, K., Voyer, D., Bogdanov, A., and 688 P. Mattes, "Segment Routing Policy Architecture", draft- 689 ietf-spring-segment-routing-policy-08 (work in progress), 690 July 2020. 692 [I-D.ietf-pce-pcep-extension-for-pce-controller] 693 Li, Z., Peng, S., Negi, M., Zhao, Q., and C. Zhou, "PCEP 694 Procedures and Protocol Extensions for Using PCE as a 695 Central Controller (PCECC) of LSPs", draft-ietf-pce-pcep- 696 extension-for-pce-controller-07 (work in progress), 697 September 2020. 699 [I-D.ietf-pce-pcep-yang] 700 Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A 701 YANG Data Model for Path Computation Element 702 Communications Protocol (PCEP)", draft-ietf-pce-pcep- 703 yang-14 (work in progress), July 2020. 705 Appendix A. Contributor Addresses 707 Dhruv Dhody 708 Huawei Technologies 709 Divyashree Techno Park, Whitefield 710 Bangalore, Karnataka 560066 711 India 713 EMail: dhruv.ietf@gmail.com 715 Mahendra Singh Negi 716 RtBrick India 717 N-17L, Floor-1, 18th Cross Rd, HSR Layout Sector-3 718 Bangalore, Karnataka 560102 719 India 721 EMail: mahend.ietf@gmail.com 723 Mike Koldychev 724 Cisco Systems, Inc. 725 2000 Innovation Drive 726 Kanata, Ontario K2K 3E8 727 Canada 729 Email: mkoldych@cisco.com 731 Zafar Ali 732 Cisco Systems, Inc. 734 Email: zali@cisco.com 736 Authors' Addresses 738 Siva Sivabalan 739 Ciena Corporation 741 EMail: msiva282@gmail.com 743 Clarence Filsfils 744 Cisco Systems, Inc. 745 Pegasus Parc 746 De kleetlaan 6a, DIEGEM BRABANT 1831 747 BELGIUM 749 EMail: cfilsfil@cisco.com 750 Jeff Tantsura 751 Apstra, Inc. 753 EMail: jefftant.ietf@gmail.com 755 Jonathan Hardwick 756 Metaswitch Networks 757 100 Church Street 758 Enfield, Middlesex 759 UK 761 EMail: Jonathan.Hardwick@metaswitch.com 763 Stefano Previdi 764 Huawei Technologies 766 EMail: stefano@previdi.net 768 Cheng Li 769 Huawei Technologies 770 Huawei Campus, No. 156 Beiqing Rd. 771 Beijing 100095 772 China 774 EMail: chengli13@huawei.com