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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in RFCs) == Unused Reference: 'RFC8283' is defined on line 419, but no explicit reference was found in the text == Outdated reference: A later version (-07) exists of draft-ietf-pce-state-sync-01 ** Downref: Normative reference to an Informational RFC: RFC 4655 ** Downref: Normative reference to an Informational RFC: RFC 8283 Summary: 2 errors (**), 0 flaws (~~), 3 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 PCE R. Chen 3 Internet-Draft ch. Zhu 4 Intended status: Standards Track B. Xu 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 14 draft-chen-pce-pcep-extension-pce-controller-bier-03 16 Abstract 18 This draft specify a new mechanism where PCE allocates the BIER 19 information centrally and uses PCEP to distribute them to all nodes, 20 then PCC generate a "Bit Index Forwarding Table"(BIFT). 22 Status of This Memo 24 This Internet-Draft is submitted in full conformance with the 25 provisions of BCP 78 and BCP 79. 27 Internet-Drafts are working documents of the Internet Engineering 28 Task Force (IETF). Note that other groups may also distribute 29 working documents as Internet-Drafts. The list of current Internet- 30 Drafts is at https://datatracker.ietf.org/drafts/current/. 32 Internet-Drafts are draft documents valid for a maximum of six months 33 and may be updated, replaced, or obsoleted by other documents at any 34 time. It is inappropriate to use Internet-Drafts as reference 35 material or to cite them other than as "work in progress." 37 This Internet-Draft will expire on 7 September 2022. 39 Copyright Notice 41 Copyright (c) 2022 IETF Trust and the persons identified as the 42 document authors. All rights reserved. 44 This document is subject to BCP 78 and the IETF Trust's Legal 45 Provisions Relating to IETF Documents (https://trustee.ietf.org/ 46 license-info) in effect on the date of publication of this document. 47 Please review these documents carefully, as they describe your rights 48 and restrictions with respect to this document. Code Components 49 extracted from this document must include Revised BSD License text as 50 described in Section 4.e of the Trust Legal Provisions and are 51 provided without warranty as described in the Revised BSD License. 53 Table of Contents 55 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 56 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 57 2. PCECC BIER Requirements . . . . . . . . . . . . . . . . . . . 3 58 3. Procedures for Using the PCE as the Central Controller (PCECC) 59 in BIER . . . . . . . . . . . . . . . . . . . . . . . . . 4 60 3.1. PCECC Capability Advertisement . . . . . . . . . . . . . 4 61 3.2. New BIER Path Setup . . . . . . . . . . . . . . . . . . . 4 62 3.3. PCECC BIER information allocation and Generation of 63 BFIT . . . . . . . . . . . . . . . . . . . . . . . . . . 4 64 3.4. Redundant PCEs . . . . . . . . . . . . . . . . . . . . . 5 65 3.5. Re Delegation and Cleanup . . . . . . . . . . . . . . . . 5 66 3.6. Synchronization of BIER information Allocations . . . . . 5 67 4. PCEP extension . . . . . . . . . . . . . . . . . . . . . . . 5 68 4.1. The OPEN Object . . . . . . . . . . . . . . . . . . . . . 5 69 4.1.1. PCECC Capability sub-TLV . . . . . . . . . . . . . . 5 70 4.2. PATH-SETUP-TYPE TLV . . . . . . . . . . . . . . . . . . . 6 71 4.3. CCI object . . . . . . . . . . . . . . . . . . . . . . . 6 72 4.3.1. BIER Encapsulation Sub TLV . . . . . . . . . . . . . 7 73 4.3.2. Address TLVs . . . . . . . . . . . . . . . . . . . . 8 74 4.4. FEC Object . . . . . . . . . . . . . . . . . . . . . . . 8 75 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8 76 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 77 7. Security Considerations . . . . . . . . . . . . . . . . . . . 8 78 8. Normative References . . . . . . . . . . . . . . . . . . . . 8 79 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 81 1. Introduction 83 [RFC8283]introduces the architecture for PCE as a central controller 84 as an extension of the architecture described in [RFC4655] and 85 assumes the continued use of PCEP as the protocol used between PCE 86 and PCC. [RFC8283]further examines the motivations and applicability 87 for PCEP as a Southbound Interface (SBI), and introduces the 88 implications for the protocol. 90 [RFC9050] specify the procedures and PCEP protocol extensions for 91 using the PCE as the central controller for static LSPs, where LSPs 92 can be provisioned as explicit label instructions at each hop on the 93 end-to-end path. Each router along the path must be told what label- 94 forwarding instructions to program and what resources to reserve. 95 The PCE-based controller keeps a view of the network and determines 96 the paths of the end-to-end LSPs, and the controller uses PCEP to 97 communicate with each router along the path of the end-to-end LSP. 99 [RFC8279] defines a Bit Index Explicit Replication (BIER) 100 architecture where all intended multicast receivers are encoded as a 101 bitmask in the multicast packet header within different 102 encapsulations such as described in [RFC8296]. A router that 103 receives such a packet will forward the packet based on the bit 104 position in the packet header towards the receiver(s) following a 105 precomputed tree for each of the bits in the packet. Each receiver 106 is represented by a unique bit in the bitmask. 108 In order to reduce the transmission of redundant information, the 109 PCE-based controllers do not allocate the BFIT directly. Instead, 110 the PCC generates the BFIT based on the received bier informations or 111 the node calculates the nexthop by itself. This document specifies 112 the procedures and PCEP protocol extensions when a PCE-based 113 controller is also responsible for configuring the BIER informations. 115 1.1. Requirements Language 117 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 118 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 119 document are to be interpreted as described in RFC 2119 [RFC2119]. 121 2. PCECC BIER Requirements 123 Following key requirements for PCECC-BIER should be considered 124 when`designing the PCECC based solution: 126 * PCEP speaker supporting this draft needs to have the capability to 127 advertise its PCECC-BIER capability to its peers. 129 * PCEP speaker not supporting this draft needs to be able to reject 130 PCECC-BIER related message with a reason code that indicates no 131 support for PCECC. 133 * PCEP procedures needs to provide a means to update (or cleanup) 134 the BIER related informations (BIER subdomain-id, BFR-id and BSL 135 etc) to the PCC. 137 * PCEP procedures needs to provide a means to update (or cleanup) 138 the "Bit Index Forwarding Table"(BIFT) to the PCC. 140 * PCEP procedures needs to provide a means to synchronize the BIER 141 related informations (BIER subdomain-id, BFR-id and BSL etc) 142 between PCE to PCC in the PCEP messages. 144 3. Procedures for Using the PCE as the Central Controller (PCECC) in 145 BIER 147 Active stateful PCE is described in [RFC8231]. PCE as a central 148 controller (PCECC) reuses existing Active stateful PCE mechanism as 149 much as possible to control the LSP. 151 This document uses the same PCEP messages and its extensions which 152 are described in [RFC9050] for PCECC-BIER as well. 154 PCEP messages PCRpt, PCInitiate, PCUpd are also used to send LSP 155 Reports, LSP setup and LSP update respectively. The extended 156 PCInitiate message described in [RFC9050] is used to download or 157 cleanup central controller's instructions (CCIs) (BIER related 158 informations and "Bit Index Forwarding Table"(BIFT) in scope of this 159 document). The extended PCRpt message described in [RFC9050] is also 160 used to report the CCIs (BIER related informations) from PCC to 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. 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 B-bit in PCECC-CAPABILITY sub-TLV for BIER. 174 3.2. New BIER Path Setup 176 The PCEP messages pertaining to PCECC-BIER MUST include PATH-SETUP- 177 TYPE TLV [RFC8408] with PST=TBD in the SRP object to clearly identify 178 the PCECC-BIER is intended. 180 3.3. PCECC BIER information allocation and Generation of BFIT 182 There are two ways to generate a "Bit Index Forwarding Table"(BIFT): 184 * The PCECC allocate parameters(BIER subdomain-id, BFR-id, BAR and 185 IPA) carried by CCI object, parameters(BFR prefix, BSL, 186 Encapsulation Type, BIFT ID, and Max SI) carried by BIER 187 Encapsulation TLV and parameters (BFR prefix)carried by OFEC 188 Object to the PCC. On receiving the BIER informations allocation, 189 each node (PCC) uses IGP protocol to distribute BIER related 190 information to other nodes. The node calculate the nexthop. In 191 this case, Each node (PCC) only needs to be allocated its own BIER 192 informations by the PCECC. 194 * In scenarios where the IGP protocol is not used/available,Each 195 node (PCC) is allocated its own and neighbor BIER informations by 196 the PCECC, then PCC generates a BIFT based on the informations it 197 receives. The BIER informations include BIER subdomain-id and 198 BFR-id carried by CCI object, BFR prefix, BSL, Encapsulation Type, 199 BIFT ID, and Max SI carried by BIER Encapsulation TLV , BFR-NBR 200 carried by Address TLV and BFR prefix carried by OFEC Object. The 201 BIFT mainly includes BFR ID, F-BM and BFR nexthop. 203 3.4. Redundant PCEs 205 [I-D.ietf-pce-state-sync] describes synchronization mechanism between 206 the stateful PCEs. The BIER informations allocated by a PCE MUST 207 also be synchronized among PCEs for PCECC BIER state synchronization. 209 3.5. Re Delegation and Cleanup 211 [RFC9050] describes the action needed for CCIs for the Basic PCECC 212 LSP on this terminated session. Similarly actions should be applied 213 for the BIER information as well. 215 3.6. Synchronization of BIER information Allocations 217 [RFC9050] describes the synchronization of Central Controller's 218 Instructions (CCI) via LSP state synchronization as described in 219 [RFC8231] and [RFC8232].Same procedures should be applied for BIER 220 informations as well. 222 4. PCEP extension 224 4.1. The OPEN Object 226 4.1.1. PCECC Capability sub-TLV 228 [RFC9050] defined the PCECC-CAPABILITY TLV. A new B-bit is defined 229 in PCECC-CAPABILITY sub-TLV for PCECC-BIER: 231 0 1 2 3 232 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 1 233 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 234 | Type=TBD | Length | 235 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 236 | Flags |B|I|S| 237 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 239 Figure 1 241 where: 243 B (PCECC-BIER-CAPABILITY - 1 bit): If set to 1 by a PCEP speaker, it 244 indicates that the PCEP speaker is capable for PCECC-BIER capability 245 and PCE would allocate BIER information on this session. 247 4.2. PATH-SETUP-TYPE TLV 249 The PATH-SETUP-TYPE TLV is defined in [RFC8408]. PST = TBD is used 250 when Path is setup via PCECC BIER mode.On a PCRpt/PCUpd/PCInitiate 251 message, the PST=TBD indicates that this path was setup via a PCECC- 252 BIER based mechanism where either the BIER informations and BIER 253 forwarding entries were allocated/instructed by PCE via PCECC 254 mechanism. 256 4.3. CCI object 258 The Central Control Instructions (CCI) Object is used by the PCE to 259 specify the forwarding instructions is defined in [RFC9050]. This 260 document defines another object-type for BIER purpose. 262 CCI Object-Type is TBD for BIER as below 264 0 1 2 3 265 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 1 266 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 267 | CC-ID | 268 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 269 | subdomain-ID | BAR | IPA | Flags | 270 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 271 | BFR-ID | Reserved | 272 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 273 | | 274 // Optional TLV // 275 | | 276 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 277 Figure 2 279 where: 281 The field CC-ID is as described in [RFC9050]. 283 BIER subdomain-ID: Unique value identifying the BIER subdomain. (as 284 defined in [RFC8401]. 286 BAR:BIER Algorithm, as documented in [RFC8401]. Specifies a BIER- 287 specific algorithm used to calculate underlay paths to reach BFERs. 288 Values are allocated from the "BIER Algorithms" registry. 290 IPA:IGP Algorithm, as documented in [RFC8401]. Specifies an IGP 291 Algorithm to either modify, enhance, or replace the calculation of 292 underlay paths to reach BFERs as defined by the BAR value. Values 293 are from the IGP Algorithm registry. 1 octet. 295 Flags (16 bit): A field used to carry any additional information 296 pertaining to the CCI. 298 BFR-ID: A 2-octet field encoding the BFR-id, as documented in 299 [RFC8279]. 301 Optional TLV: There are two optional TLV are defined/reused in this 302 draft. 304 4.3.1. BIER Encapsulation Sub TLV 306 0 1 2 3 307 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 1 308 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 309 | Type | Length | 310 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 311 | Flags | ET| Reserved | 312 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 313 | Max SI |BS Len | BIFT-id | 314 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 316 Figure 3 318 where: 320 The code point for the TLV type is to be defined by IANA. 322 Length:4 323 ET-Flag:ET(Encapsulation type) Flag,There are two Encapsulation 324 Types: 326 * 0b00-MPLS encapsulation. 328 * 0b01-Non-MPLS encapsulation. 330 Max SI: A 1 octet field encoding the Maximum Set Identifier(Section 1 331 of [RFC8279] ) used in the encapsulation for this BIER subdomain for 332 this BitString length. 334 Local BitString Length (BS Len): Encoded BitString length as per 335 [RFC8296]. 337 BIFT-id: A 20 bit field encoding the first BIFT-id of the BIFT-id 338 range. 340 4.3.2. Address TLVs 342 Address TLVs described in [RFC9050] are used to associate the next- 343 hop information, so we Reuse ADDRESS TLV to carry the BFR out- 344 interface and nexthop informations. 346 4.4. FEC Object 348 BIER information is always associated with a host prefix, so we reuse 349 FEC Object 1'IPv4 Node ID' and FEC Object-Type 2 'IPv6 Node ID' 350 defined in [RFC8664] to carry the BFR prefix. 352 5. Acknowledgements 354 We would like to thank Dhruv Dhody for their useful comments and 355 suggestions. 357 6. IANA Considerations 359 TBD. 361 7. Security Considerations 363 The PCECC extension are based on the existing PCEP messages and thus 364 the security considerations described in 366 The PCECC extension are based on the existing PCEP messages and thus 367 the security considerations described in [RFC5440] ,[RFC8231] 368 ,[RFC8281], and [RFC9050] apply to this draft. 370 8. Normative References 372 [I-D.ietf-pce-state-sync] 373 Litkowski, S., Sivabalan, S., Li, C., and H. Zheng, "Inter 374 Stateful Path Computation Element (PCE) Communication 375 Procedures.", Work in Progress, Internet-Draft, draft- 376 ietf-pce-state-sync-01, 20 October 2021, 377 . 380 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 381 Requirement Levels", BCP 14, RFC 2119, 382 DOI 10.17487/RFC2119, March 1997, 383 . 385 [RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path 386 Computation Element (PCE)-Based Architecture", RFC 4655, 387 DOI 10.17487/RFC4655, August 2006, 388 . 390 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 391 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 392 DOI 10.17487/RFC5440, March 2009, 393 . 395 [RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path 396 Computation Element Communication Protocol (PCEP) 397 Extensions for Stateful PCE", RFC 8231, 398 DOI 10.17487/RFC8231, September 2017, 399 . 401 [RFC8232] Crabbe, E., Minei, I., Medved, J., Varga, R., Zhang, X., 402 and D. Dhody, "Optimizations of Label Switched Path State 403 Synchronization Procedures for a Stateful PCE", RFC 8232, 404 DOI 10.17487/RFC8232, September 2017, 405 . 407 [RFC8279] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., 408 Przygienda, T., and S. Aldrin, "Multicast Using Bit Index 409 Explicit Replication (BIER)", RFC 8279, 410 DOI 10.17487/RFC8279, November 2017, 411 . 413 [RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path 414 Computation Element Communication Protocol (PCEP) 415 Extensions for PCE-Initiated LSP Setup in a Stateful PCE 416 Model", RFC 8281, DOI 10.17487/RFC8281, December 2017, 417 . 419 [RFC8283] Farrel, A., Ed., Zhao, Q., Ed., Li, Z., and C. Zhou, "An 420 Architecture for Use of PCE and the PCE Communication 421 Protocol (PCEP) in a Network with Central Control", 422 RFC 8283, DOI 10.17487/RFC8283, December 2017, 423 . 425 [RFC8296] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., 426 Tantsura, J., Aldrin, S., and I. Meilik, "Encapsulation 427 for Bit Index Explicit Replication (BIER) in MPLS and Non- 428 MPLS Networks", RFC 8296, DOI 10.17487/RFC8296, January 429 2018, . 431 [RFC8401] Ginsberg, L., Ed., Przygienda, T., Aldrin, S., and Z. 432 Zhang, "Bit Index Explicit Replication (BIER) Support via 433 IS-IS", RFC 8401, DOI 10.17487/RFC8401, June 2018, 434 . 436 [RFC8408] Sivabalan, S., Tantsura, J., Minei, I., Varga, R., and J. 437 Hardwick, "Conveying Path Setup Type in PCE Communication 438 Protocol (PCEP) Messages", RFC 8408, DOI 10.17487/RFC8408, 439 July 2018, . 441 [RFC8664] Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W., 442 and J. Hardwick, "Path Computation Element Communication 443 Protocol (PCEP) Extensions for Segment Routing", RFC 8664, 444 DOI 10.17487/RFC8664, December 2019, 445 . 447 [RFC9050] Li, Z., Peng, S., Negi, M., Zhao, Q., and C. Zhou, "Path 448 Computation Element Communication Protocol (PCEP) 449 Procedures and Extensions for Using the PCE as a Central 450 Controller (PCECC) of LSPs", RFC 9050, 451 DOI 10.17487/RFC9050, July 2021, 452 . 454 Authors' Addresses 456 Ran Chen 457 ZTE Corporation 458 Nanjing 459 China 460 Email: chen.ran@zte.com.cn 462 Chun Zhu 463 ZTE Corporation 464 Nanjing 465 China 466 Email: zhu.chun@zte.com.cn 468 BenChong Xu 469 ZTE Corporation 470 Nanjing 471 China 472 Email: xu.benchong@zte.com.cn 474 Huaimo Chen 475 Futurewei 476 Nanjing, 477 United States of America 478 Email: Huaimo.chen@futurewei.com 480 Aijun Wang 481 China Telecom 482 Nanjing 483 China 484 Email: wangaj3@chinatelecom.cn