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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 PCE R. Chen 3 Internet-Draft B. Xu 4 Intended status: Standards Track ch. Zhu 5 Expires: 7 September 2022 ZTE Corporation 6 H. Chen 7 Futurewei 8 A. Wang 9 China Telecom 10 6 March 2022 12 PCEP Procedures and Protocol Extensions for Using PCE as a Central 13 Controller (PCECC) of BIER-TE 14 draft-chen-pce-controller-bier-te-03 16 Abstract 18 This draft specify extensions to PCEP protocol when a PCE-based 19 controller is responsible for allocates the BIER-TE information(BIER 20 subdomain-id, adjacencies BitPosition(s), and Adjacency Types etc), 21 then PCC generate a "Bit Index Forwarding Table"(BIFT). 23 Status of This Memo 25 This Internet-Draft is submitted in full conformance with the 26 provisions of BCP 78 and BCP 79. 28 Internet-Drafts are working documents of the Internet Engineering 29 Task Force (IETF). Note that other groups may also distribute 30 working documents as Internet-Drafts. The list of current Internet- 31 Drafts is at https://datatracker.ietf.org/drafts/current/. 33 Internet-Drafts are draft documents valid for a maximum of six months 34 and may be updated, replaced, or obsoleted by other documents at any 35 time. It is inappropriate to use Internet-Drafts as reference 36 material or to cite them other than as "work in progress." 38 This Internet-Draft will expire on 7 September 2022. 40 Copyright Notice 42 Copyright (c) 2022 IETF Trust and the persons identified as the 43 document authors. All rights reserved. 45 This document is subject to BCP 78 and the IETF Trust's Legal 46 Provisions Relating to IETF Documents (https://trustee.ietf.org/ 47 license-info) in effect on the date of publication of this document. 48 Please review these documents carefully, as they describe your rights 49 and restrictions with respect to this document. Code Components 50 extracted from this document must include Revised BSD License text as 51 described in Section 4.e of the Trust Legal Provisions and are 52 provided without warranty as described in the Revised BSD License. 54 Table of Contents 56 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 57 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 58 2. PCECC BIER Requirements . . . . . . . . . . . . . . . . . . . 3 59 3. Procedures for Using the PCE as the Central Controller (PCECC) 60 in BIER-TE . . . . . . . . . . . . . . . . . . . . . . . 4 61 3.1. PCECC Capability Advertisement . . . . . . . . . . . . . 4 62 3.2. New BIER Path Setup . . . . . . . . . . . . . . . . . . . 4 63 3.3. PCECC BIER-TE information allocation and Generation of 64 BFIT . . . . . . . . . . . . . . . . . . . . . . . . . . 4 65 3.4. Redundant PCEs . . . . . . . . . . . . . . . . . . . . . 5 66 3.5. Re Delegation and Cleanup . . . . . . . . . . . . . . . . 5 67 3.6. Synchronization of BIER-TE information Allocations . . . 5 68 4. PCEP extension . . . . . . . . . . . . . . . . . . . . . . . 5 69 4.1. The OPEN Object . . . . . . . . . . . . . . . . . . . . . 5 70 4.1.1. PCECC Capability sub-TLV . . . . . . . . . . . . . . 5 71 4.2. PATH-SETUP-TYPE TLV . . . . . . . . . . . . . . . . . . . 6 72 4.3. CCI object . . . . . . . . . . . . . . . . . . . . . . . 6 73 4.3.1. BIER Encapsulation Sub TLV . . . . . . . . . . . . . 7 74 4.3.2. Address TLVs . . . . . . . . . . . . . . . . . . . . 7 75 4.3.3. ROUTE-DISTINGUISHER TLV . . . . . . . . . . . . . . . 7 76 4.4. FEC Object . . . . . . . . . . . . . . . . . . . . . . . 8 77 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8 78 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 79 7. Security Considerations . . . . . . . . . . . . . . . . . . . 8 80 8. Normative References . . . . . . . . . . . . . . . . . . . . 8 81 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 83 1. Introduction 85 [RFC8283]introduces the architecture for PCE as a central controller 86 as an extension of the architecture described in[RFC4655] and assumes 87 the continued use of PCEP as the protocol used between PCE and PCC. 88 [RFC8283]further examines the motivations and applicability for PCEP 89 as a Southbound Interface (SBI), and introduces the implications for 90 the protocol. 92 [RFC9050]specify the procedures and PCEP protocol extensions for 93 using the PCE as the central controller for static LSPs, where LSPs 94 can be provisioned as explicit label instructions at each hop on the 95 end-to-end path. Each router along the path must be told what label- 96 forwarding instructions to program and what resources to reserve. 98 The PCE-based controller keeps a view of the network and determines 99 the paths of the end-to-end LSPs, and the controller uses PCEP to 100 communicate with each router along the path of the end-to-end LSP. 102 Bit Index Explicit Replication (BIER)-TE shares architecture and 103 packet formats with BIER as described in [RFC8279]. BIER-TE forwards 104 and replicates packets based on a BitString in the packet header, but 105 every BitPosition of the BitString of a BIER-TE packet indicates one 106 or more adjacencies as described in [I-D.ietf-bier-te-arch]. 108 This draft specify extensions to PCEP protocol when a PCE-based 109 controller is responsible for allocates the BIER-TE information(BIER 110 subdomain-id, adjacencies BitPosition(s), and Adjacency Types etc), 111 then PCC generate a "Bit Index Forwarding Table"(BIFT). 113 1.1. Requirements Language 115 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 116 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 117 document are to be interpreted as described in RFC 2119 [RFC2119]. 119 2. PCECC BIER Requirements 121 Following key requirements for PCECC-BIER should be considered 122 when`designing the PCECC based solution: 124 * PCEP speaker supporting this draft needs to have the capability to 125 advertise its PCECC BIER-TE capability to its peers. 127 * PCEP speaker not supporting this draft needs to be able to reject 128 PCECC BIER-TE related message with a reason code that indicates no 129 support for PCECC. 131 * PCEP procedures needs to provide a means to update (or cleanup) 132 the BIER-TE related informations (BIER subdomain-id, adjacencies 133 BitPosition(s), and Adjacency Types etc) to the PCC. 135 * PCEP procedures needs to provide a means to update (or cleanup) 136 the BIER-TE "Bit Index Forwarding Table" (BIFT) to the PCC. 138 * PCEP procedures needs to provide a means to synchronize the BIER- 139 TE related informations(BIER subdomain-id, adjacencies 140 BitPosition(s), and Adjacency Types etc) between PCE to PCC in the 141 PCEP messages. 143 3. Procedures for Using the PCE as the Central Controller (PCECC) in 144 BIER-TE 146 Active stateful PCE is described in [RFC8231]. PCE as a central 147 controller (PCECC) reuses existing Active stateful PCE mechanism as 148 much as possible to control the LSP. 150 This document uses the same PCEP messages and its extensions which 151 are described in [RFC9050] for PCECC BIER-TE as well. 153 PCEP messages PCRpt, PCInitiate, PCUpd are also used to send LSP 154 Reports, LSP setup and LSP update respectively. The extended 155 PCInitiate message described in [RFC9050] is used to download or 156 cleanup central controller's instructions (CCIs) (BIER-TE related 157 informations and "Bit Index Forwarding Table" (BIFT) in scope of this 158 document). The extended PCRpt message described in [RFC9050] is also 159 used to report the CCIs (BIER-TE related informations) from PCC to 160 PCE. 162 [RFC9050] specify an object called CCI for the encoding of central 163 controller's instructions. This document extends the CCI by defining 164 another object-type for BIER-TE. 166 3.1. PCECC Capability Advertisement 168 During PCEP Initialization Phase, PCEP Speakers (PCE or PCC) 169 advertise their support of PCECC extensions. A PCEP Speaker includes 170 the "PCECC Capability" sub-TLV, described in [RFC9050]. 172 This document adds T-bit in PCECC-CAPABILITY sub-TLV for BIER-TE. 174 3.2. New BIER Path Setup 176 The PCEP messages pertaining to PCECC BIER-TE MUST include PATH- 177 SETUP-TYPE TLV [RFC8408] with PST=TBD in the SRP object to clearly 178 identify the PCECC BIER-TE is intended. 180 3.3. PCECC BIER-TE information allocation and Generation of BFIT 182 Each node (PCC) is allocated a node BIER-TE information by the PCECC. 183 The BIER-TE information mainly includes BIER subdomain-id, 184 adjacencies BitPosition(s), and Adjacency Types etc. In scenarios 185 where the IGP protocol is not used/available, Each node (PCC) is 186 allocated its own and neighbor BIER-TE informations by the PCECC, 187 then PCC generates a BIFT based on the informations it receives. The 188 BIFT mainly includes BFR ID, F-BM and BFR nexthop. 190 3.4. Redundant PCEs 192 [I-D.ietf-pce-state-sync] describes synchronization mechanism between 193 the stateful PCEs. The BIER-TE informations allocated by a PCE MUST 194 also be synchronized among PCEs for PCECC BIER-TE state 195 synchronization. 197 3.5. Re Delegation and Cleanup 199 [RFC9050] describes the action needed for CCIs for the Basic PCECC 200 LSP on this terminated session.Similarly actions should be applied 201 for the BIER-TE information as well. 203 3.6. Synchronization of BIER-TE information Allocations 205 [RFC9050] describes the synchronization of Central Controller's 206 Instructions (CCI) via LSP state synchronization as described in 207 [RFC8231] and [RFC8232].Same procedures should be applied for BIER-TE 208 information and "Bit Index Forwarding Table" (BIFT) allocations as 209 well. 211 4. PCEP extension 213 4.1. The OPEN Object 215 4.1.1. PCECC Capability sub-TLV 217 [RFC9050] defined the PCECC-CAPABILITY TLV. A new T-bit is defined 218 in PCECC-CAPABILITY sub-TLV for PCECC BIER-TE: 220 0 1 2 3 221 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 1 222 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 223 | Type=TBD | Length | 224 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 225 | Flags |T|I|S| 226 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 228 Figure 1 230 where: 232 T (PCECC BIER-TE CAPABILITY - 1 bit): If set to 1 by a PCEP speaker, 233 it indicates that the PCEP speaker is capable for PCECC BIER-TE 234 capability and PCE would allocate BIER-TE information on this 235 session. 237 4.2. PATH-SETUP-TYPE TLV 239 The PATH-SETUP-TYPE TLV is defined in [RFC8408]. PST = TBD is used 240 when Path is setup via PCECC BIER-TE mode.On a PCRpt/PCUpd/PCInitiate 241 message, the PST=TBD indicates that this path was setup via a PCECC 242 BIER-TE based mechanism where either the BIER-TE informations and 243 BIER-TE "Bit Index Forwarding Table" (BIFT) were allocated/instructed 244 by PCE via PCECC mechanism. 246 4.3. CCI object 248 The Central Control Instructions (CCI) Object is used by the PCE to 249 specify the forwarding instructions is defined in [RFC9050]. This 250 document defines another object-type for BIER-TE purpose. 252 CCI Object-Type is TBD for BIER-TE as below 254 0 1 2 3 255 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 1 256 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 257 | CC-ID | 258 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 259 | subdomain-ID | BSL | Flags | 260 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 261 | SI |adj-t| BitPosition | Reserved| 262 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 263 | | 264 // Optional TLV // 265 | | 266 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 268 Figure 2 270 where: 272 The field CC-ID is as described in [RFC9050]. 274 BIER subdomain-ID: Unique value identifying the BIER subdomain. (as 275 defined in [RFC8401]. 277 BSL: A 1 octet field encodes the length in bits of the BitString as 278 per [RFC8296], the maximum length of the BitString is 5,it indicates 279 the length of BitString is 1024.It is used to refer to the number of 280 bits in the BitString. 282 SI: Set Identifier (Section 1 of [RFC8279] used in the encapsulation 283 for this BIER subdomain for this BitString length, 1 octet. 285 BitPositions: BitPositions indicate adjacencies,16bit. 287 The "Reserved" (1 octets) fields are currently unused, and MUST be 288 set to zero on transmission and ignored on reception. 290 Adjacency Types:There are three types in this document. 292 * 0b000:Forward Connected. 294 * 0b001:Forward Routed. 296 * 0b010: Local Decap. 298 * ECMP will discuss in next version. 300 Optional TLV: There are three optional TLV are defined/reused in this 301 draft. 303 4.3.1. BIER Encapsulation Sub TLV 305 BIER Encapsulation Sub-TLV defined in 306 [I-D.chen-pce-pcep-extension-pce-controller-bier] are used to 307 associate BIER Encapsulation information, so we Reuse BIER 308 Encapsulation Sub-TLV to carry the BIER-TE Encapsulation 309 informations. 311 4.3.2. Address TLVs 313 When the adjacency type is 0b000:Forward Connected, the BFR address 314 information (BFR out-interface and nexthop informations) should be 315 carried in the CCI Object. 317 Address TLVs described in [RFC9050] are used to associate the next- 318 hop information, so we Reuse ADDRESS TLV to carry the BFR out- 319 interface and nexthop informations. 321 4.3.3. ROUTE-DISTINGUISHER TLV 323 When the adjacency type is 0b001: Forward Routed, a VRF and the next- 324 hop informations should be carried in the CCI Object, so we reuse the 325 ROUTE-DISTINGUISHER TLV defined in [RFC9168] and Address TLVs defined 326 in [RFC9050] to carry the next hop is associated with a specific VPN 327 identified by the RD. 329 When the adjacency type is 0b010: Local Decap, only a VRF should be 330 carried in the CCI Object. Reuse the ROUTE-DISTINGUISHER TLV which 331 is defined in [RFC9168] carries an RD value, used to identify a VRF. 333 4.4. FEC Object 335 BIER-TE information is always associated with adjacency, so we reuse 336 FEC Object 1'IPv4 Node ID' and FEC Object-Type 2 'IPv6 Node ID' 337 defined in [RFC8664] to clearly identify the adjacency for which a 338 SI: BitPosition is being allocated. 340 5. Acknowledgements 342 We would like to thank Dhruv Dhody for their useful comments and 343 suggestions. 345 6. IANA Considerations 347 TBD. 349 7. Security Considerations 351 The PCECC extension are based on the existing PCEP messages and thus 352 the security considerations described in 354 The PCECC extension are based on the existing PCEP messages and thus 355 the security considerations described in [RFC5440] ,[RFC8231] 356 ,[RFC8281], and [RFC9050] apply to this draft. 358 8. Normative References 360 [I-D.chen-pce-pcep-extension-pce-controller-bier] 361 Chen, R. and B. Xu, "PCEP Procedures and Protocol 362 Extensions for Using PCE as a Central Controller (PCECC) 363 of BIER", Work in Progress, Internet-Draft, draft-chen- 364 pce-pcep-extension-pce-controller-bier-02, 24 December 365 2021, . 368 [I-D.ietf-bier-te-arch] 369 Eckert, T., Menth, M., and G. Cauchie, "Tree Engineering 370 for Bit Index Explicit Replication (BIER-TE)", Work in 371 Progress, Internet-Draft, draft-ietf-bier-te-arch-12, 28 372 January 2022, . 375 [I-D.ietf-pce-state-sync] 376 Litkowski, S., Sivabalan, S., Li, C., and H. Zheng, "Inter 377 Stateful Path Computation Element (PCE) Communication 378 Procedures.", Work in Progress, Internet-Draft, draft- 379 ietf-pce-state-sync-01, 20 October 2021, 380 . 383 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 384 Requirement Levels", BCP 14, RFC 2119, 385 DOI 10.17487/RFC2119, March 1997, 386 . 388 [RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path 389 Computation Element (PCE)-Based Architecture", RFC 4655, 390 DOI 10.17487/RFC4655, August 2006, 391 . 393 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 394 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 395 DOI 10.17487/RFC5440, March 2009, 396 . 398 [RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path 399 Computation Element Communication Protocol (PCEP) 400 Extensions for Stateful PCE", RFC 8231, 401 DOI 10.17487/RFC8231, September 2017, 402 . 404 [RFC8232] Crabbe, E., Minei, I., Medved, J., Varga, R., Zhang, X., 405 and D. Dhody, "Optimizations of Label Switched Path State 406 Synchronization Procedures for a Stateful PCE", RFC 8232, 407 DOI 10.17487/RFC8232, September 2017, 408 . 410 [RFC8279] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., 411 Przygienda, T., and S. Aldrin, "Multicast Using Bit Index 412 Explicit Replication (BIER)", RFC 8279, 413 DOI 10.17487/RFC8279, November 2017, 414 . 416 [RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path 417 Computation Element Communication Protocol (PCEP) 418 Extensions for PCE-Initiated LSP Setup in a Stateful PCE 419 Model", RFC 8281, DOI 10.17487/RFC8281, December 2017, 420 . 422 [RFC8283] Farrel, A., Ed., Zhao, Q., Ed., Li, Z., and C. Zhou, "An 423 Architecture for Use of PCE and the PCE Communication 424 Protocol (PCEP) in a Network with Central Control", 425 RFC 8283, DOI 10.17487/RFC8283, December 2017, 426 . 428 [RFC8296] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., 429 Tantsura, J., Aldrin, S., and I. Meilik, "Encapsulation 430 for Bit Index Explicit Replication (BIER) in MPLS and Non- 431 MPLS Networks", RFC 8296, DOI 10.17487/RFC8296, January 432 2018, . 434 [RFC8401] Ginsberg, L., Ed., Przygienda, T., Aldrin, S., and Z. 435 Zhang, "Bit Index Explicit Replication (BIER) Support via 436 IS-IS", RFC 8401, DOI 10.17487/RFC8401, June 2018, 437 . 439 [RFC8408] Sivabalan, S., Tantsura, J., Minei, I., Varga, R., and J. 440 Hardwick, "Conveying Path Setup Type in PCE Communication 441 Protocol (PCEP) Messages", RFC 8408, DOI 10.17487/RFC8408, 442 July 2018, . 444 [RFC8664] Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W., 445 and J. Hardwick, "Path Computation Element Communication 446 Protocol (PCEP) Extensions for Segment Routing", RFC 8664, 447 DOI 10.17487/RFC8664, December 2019, 448 . 450 [RFC9050] Li, Z., Peng, S., Negi, M., Zhao, Q., and C. Zhou, "Path 451 Computation Element Communication Protocol (PCEP) 452 Procedures and Extensions for Using the PCE as a Central 453 Controller (PCECC) of LSPs", RFC 9050, 454 DOI 10.17487/RFC9050, July 2021, 455 . 457 [RFC9168] Dhody, D., Farrel, A., and Z. Li, "Path Computation 458 Element Communication Protocol (PCEP) Extension for Flow 459 Specification", RFC 9168, DOI 10.17487/RFC9168, January 460 2022, . 462 Authors' Addresses 464 Ran Chen 465 ZTE Corporation 466 Nanjing 467 China 468 Email: chen.ran@zte.com.cn 469 BenChong Xu 470 ZTE Corporation 471 Nanjing 472 China 473 Email: xu.benchong@zte.com.cn 475 Chun Zhu 476 ZTE Corporation 477 Nanjing 478 China 479 Email: zhu.chun@zte.com.cn 481 Huaimo Chen 482 Futurewei 483 Nanjing, 484 United States of America 485 Email: Huaimo.chen@futurewei.com 487 Aijun Wang 488 China Telecom 489 Nanjing 490 China 491 Email: wangaj3@chinatelecom.cn