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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 PCE Working Group Z. Li 3 Internet-Draft S. Peng 4 Intended status: Standards Track Huawei Technologies 5 Expires: May 5, 2021 M. Negi 6 RtBrick Inc 7 Q. Zhao 8 Etheric Networks 9 C. Zhou 10 HPE 11 November 1, 2020 13 PCEP Procedures and Protocol Extensions for Using PCE as a Central 14 Controller (PCECC) of SR-LSPs 15 draft-zhao-pce-pcep-extension-pce-controller-sr-08 17 Abstract 19 The Path Computation Element (PCE) is a core component of Software- 20 Defined Networking (SDN) systems. It can compute optimal paths for 21 traffic across a network and can also update the paths to reflect 22 changes in the network or traffic demands. 24 PCE was developed to derive paths for MPLS Label Switched Paths 25 (LSPs), which are supplied to the head end of the LSP using the Path 26 Computation Element Communication Protocol (PCEP). But SDN has a 27 broader applicability than signaled (G)MPLS traffic-engineered (TE) 28 networks, and the PCE may be used to determine paths in a range of 29 use cases. PCEP has been proposed as a control protocol for use in 30 these environments to allow the PCE to be fully enabled as a central 31 controller. 33 A PCE-based Central Controller (PCECC) can simplify the processing of 34 a distributed control plane by blending it with elements of SDN and 35 without necessarily completely replacing it. Thus, the LSP can be 36 calculated/set up/initiated and the label forwarding entries can also 37 be downloaded through a centralized PCE server to each network device 38 along the path while leveraging the existing PCE technologies as much 39 as possible. 41 This document specifies the procedures and PCEP extensions when a 42 PCE-based controller is also responsible for configuring the 43 forwarding actions on the routers, in addition to computing the paths 44 for packet flows in a segment routing (SR) network and telling the 45 edge routers what instructions to attach to packets as they enter the 46 network. 48 Status of This Memo 50 This Internet-Draft is submitted in full conformance with the 51 provisions of BCP 78 and BCP 79. 53 Internet-Drafts are working documents of the Internet Engineering 54 Task Force (IETF). Note that other groups may also distribute 55 working documents as Internet-Drafts. The list of current Internet- 56 Drafts is at https://datatracker.ietf.org/drafts/current/. 58 Internet-Drafts are draft documents valid for a maximum of six months 59 and may be updated, replaced, or obsoleted by other documents at any 60 time. It is inappropriate to use Internet-Drafts as reference 61 material or to cite them other than as "work in progress." 63 This Internet-Draft will expire on May 5, 2021. 65 Copyright Notice 67 Copyright (c) 2020 IETF Trust and the persons identified as the 68 document authors. All rights reserved. 70 This document is subject to BCP 78 and the IETF Trust's Legal 71 Provisions Relating to IETF Documents 72 (https://trustee.ietf.org/license-info) in effect on the date of 73 publication of this document. Please review these documents 74 carefully, as they describe your rights and restrictions with respect 75 to this document. Code Components extracted from this document must 76 include Simplified BSD License text as described in Section 4.e of 77 the Trust Legal Provisions and are provided without warranty as 78 described in the Simplified BSD License. 80 Table of Contents 82 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 83 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 5 84 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 85 3. PCECC SR . . . . . . . . . . . . . . . . . . . . . . . . . . 5 86 4. PCEP Requirements . . . . . . . . . . . . . . . . . . . . . . 6 87 5. Procedures for Using the PCE as a Central Controller (PCECC) 88 in Segment Routing . . . . . . . . . . . . . . . . . . . . . 6 89 5.1. Stateful PCE Model . . . . . . . . . . . . . . . . . . . 6 90 5.2. New LSP Functions . . . . . . . . . . . . . . . . . . . . 6 91 5.3. PCECC Capability Advertisement . . . . . . . . . . . . . 7 92 5.4. PCEP session IP address and TED Router ID . . . . . . . . 7 93 5.5. LSP Operations . . . . . . . . . . . . . . . . . . . . . 8 94 5.5.1. PCECC Segment Routing (SR) . . . . . . . . . . . . . 8 95 5.5.1.1. PCECC SR Node/Prefix SID allocation . . . . . . . 8 96 5.5.1.2. PCECC SR Adjacency Label allocation . . . . . . . 10 97 5.5.1.3. Redundant PCEs . . . . . . . . . . . . . . . . . 12 98 5.5.1.4. Re Delegation and Clean up . . . . . . . . . . . 12 99 5.5.1.5. Synchronization of Label Allocations . . . . . . 13 100 5.5.1.6. PCC-Based Allocations . . . . . . . . . . . . . . 13 101 5.5.1.7. Binding SID . . . . . . . . . . . . . . . . . . . 13 102 6. PCEP Messages . . . . . . . . . . . . . . . . . . . . . . . . 14 103 6.1. Central Control Instructions . . . . . . . . . . . . . . 14 104 6.1.1. The PCInitiate Message . . . . . . . . . . . . . . . 14 105 6.1.2. The PCRpt message . . . . . . . . . . . . . . . . . . 15 106 7. PCEP Objects . . . . . . . . . . . . . . . . . . . . . . . . 16 107 7.1. OPEN Object . . . . . . . . . . . . . . . . . . . . . . . 16 108 7.1.1. PCECC Capability sub-TLV . . . . . . . . . . . . . . 16 109 7.2. SR-TE Path Setup . . . . . . . . . . . . . . . . . . . . 17 110 7.3. CCI Object . . . . . . . . . . . . . . . . . . . . . . . 17 111 7.4. FEC Object . . . . . . . . . . . . . . . . . . . . . . . 19 112 8. Implementation Status . . . . . . . . . . . . . . . . . . . . 21 113 8.1. Huawei's Proof of Concept based on ONOS . . . . . . . . . 22 114 9. Security Considerations . . . . . . . . . . . . . . . . . . . 22 115 10. Manageability Considerations . . . . . . . . . . . . . . . . 22 116 10.1. Control of Function and Policy . . . . . . . . . . . . . 22 117 10.2. Information and Data Models . . . . . . . . . . . . . . 23 118 10.3. Liveness Detection and Monitoring . . . . . . . . . . . 23 119 10.4. Verify Correct Operations . . . . . . . . . . . . . . . 23 120 10.5. Requirements On Other Protocols . . . . . . . . . . . . 23 121 10.6. Impact On Network Operations . . . . . . . . . . . . . . 23 122 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23 123 11.1. PCECC-CAPABILITY sub-TLV . . . . . . . . . . . . . . . . 23 124 11.2. PCEP Object . . . . . . . . . . . . . . . . . . . . . . 24 125 11.3. PCEP-Error Object . . . . . . . . . . . . . . . . . . . 24 126 11.4. CCI Object Flag Field for SR . . . . . . . . . . . . . . 24 127 12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 25 128 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 25 129 13.1. Normative References . . . . . . . . . . . . . . . . . . 25 130 13.2. Informative References . . . . . . . . . . . . . . . . . 27 131 Appendix A. Contributor Addresses . . . . . . . . . . . . . . . 30 132 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 31 134 1. Introduction 136 The Path Computation Element (PCE) [RFC4655] was developed to offload 137 the path computation function from routers in an MPLS traffic- 138 engineered network. Since then, the role and function of the PCE has 139 grown to cover a number of other uses (such as GMPLS [RFC7025]) and 140 to allow delegated control [RFC8231] and PCE-initiated use of network 141 resources [RFC8281]. 143 According to [RFC7399], Software-Defined Networking (SDN) refers to a 144 separation between the control elements and the forwarding components 145 so that software running in a centralized system, called a 146 controller, can act to program the devices in the network to behave 147 in specific ways. A required element in an SDN architecture is a 148 component that plans how the network resources will be used and how 149 the devices will be programmed. It is possible to view this 150 component as performing specific computations to place traffic flows 151 within the network given knowledge of the availability of network 152 resources, how other forwarding devices are programmed, and the way 153 that other flows are routed. This is the function and purpose of a 154 PCE, and the way that a PCE integrates into a wider network control 155 system (including an SDN system) is presented in [RFC7491]. 157 In early PCE implementations, where the PCE was used to derive paths 158 for MPLS Label Switched Paths (LSPs), paths were requested by network 159 elements (known as Path Computation Clients (PCCs)), and the results 160 of the path computations were supplied to network elements using the 161 Path Computation Element Communication Protocol (PCEP) [RFC5440]. 162 This protocol was later extended to allow a PCE to send unsolicited 163 requests to the network for LSP establishment [RFC8281]. 165 [RFC8283] introduces the architecture for PCE as a central controller 166 as an extension of the architecture described in [RFC4655] and 167 assumes the continued use of PCEP as the protocol used between PCE 168 and PCC. [RFC8283] further examines the motivations and 169 applicability for PCEP as a Southbound Interface (SBI), and 170 introduces the implications for the protocol. 171 [I-D.ietf-teas-pcecc-use-cases] describes the use cases for the PCE- 172 based Central Controller (PCECC) architecture. 174 [I-D.ietf-pce-pcep-extension-for-pce-controller] specify the 175 procedures and PCEP extensions for using the PCE as the central 176 controller for static LSPs, where LSPs can be provisioned as explicit 177 label instructions at each hop on the end-to-end path. 179 Segment Routing (SR) technology leverages the source routing and 180 tunneling paradigms. A source node can choose a path without relying 181 on hop-by-hop signaling protocols such as LDP or RSVP-TE. Each path 182 is specified as a set of "segments" advertised by link-state routing 183 protocols (IS-IS or OSPF). [RFC8402] provides an introduction to SR 184 architecture. The corresponding IS-IS and OSPF extensions are 185 specified in [RFC8667] and [RFC8665] , respectively. It relies on a 186 series of forwarding instructions being placed in the header of a 187 packet. The segment routing architecture supports operations that 188 can be used to steer packet flows in a network, thus providing a form 189 of traffic engineering. [RFC8664] specify the SR specific PCEP 190 extensions. 192 PCECC may further use PCEP for SR SID (Segment Identifier) 193 distribution on the SR nodes with some benefits. 195 This document specifies the procedures and PCEP extensions when a 196 PCE-based controller is also responsible for configuring the 197 forwarding actions on the routers (SR SID distribution in this case), 198 in addition to computing the paths for packet flows in a segment 199 routing network and telling the edge routers what instructions to 200 attach to packets as they enter the network. 202 Only SR using MPLS dataplane (SR-MPLS) is in the scope of this 203 document. Refer [I-D.dhody-pce-pcep-extension-pce-controller-srv6] 204 for use of PCECC technique for SR in IPv6 (SRv6) dataplane. 206 1.1. Requirements Language 208 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 209 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 210 "OPTIONAL" in this document are to be interpreted as described in BCP 211 14 [RFC2119] [RFC8174] when, and only when, they appear in all 212 capitals, as shown here. 214 2. Terminology 216 Terminologies used in this document is the same as described in the 217 draft [RFC8283] and [I-D.ietf-teas-pcecc-use-cases]. 219 3. PCECC SR 221 [RFC8664] specifies extensions to PCEP that allow a stateful PCE to 222 compute, update, or initiate SR-TE paths. An ingress node of an SR- 223 TE path appends all outgoing packets with a list of MPLS labels 224 (SIDs). This is encoded in SR-ERO subobject, capable of carrying a 225 label (SID) as well as the identity of the node/adjacency label 226 (SID). 228 The notion of segment and SID is defined in [RFC8402], which fits the 229 MPLS architecture [RFC3031] as the label which is managed by a local 230 allocation process of LSR (similarly to other MPLS signaling 231 protocols) [RFC8660]. The SR information such as node/adjacency 232 label (SID) is flooded via IGP as specified in [RFC8667] and 233 [RFC8665]. 235 As per [RFC8283], PCE as a central controller can allocate and 236 provision the node/prefix/adjacency label (SID) via PCEP. 238 The rest of the processing is similar to existing stateful PCE with 239 SR mechanism. 241 For the purpose of this document, it is assumed that the label range 242 to be used by a PCE is set on both PCEP peers. Further, a global 243 label range is assumed to be set on all PCEP peers in the SR domain. 244 This document also allows a case where the label space is maintained 245 by PCC itself, and the labels are allocated by the PCC, in this case, 246 the PCE should request the allocation from PCC as described in 247 Section 5.5.1.6. 249 4. PCEP Requirements 251 Following key requirements for PCECC-SR should be considered when` 252 designing the PCECC-based solution: 254 o A PCEP speaker supporting this draft needs to have the capability 255 to advertise its PCECC-SR capability to its peers. 257 o PCEP procedures need to allow for PCC-based label/SID allocations. 259 o PCEP procedures need means to update (or clean up) the label-map 260 entry to the PCC. 262 o PCEP procedures need to provide a mean to synchronize the SR 263 labels allocations between the PCE to the PCC via PCEP messages. 265 5. Procedures for Using the PCE as a Central Controller (PCECC) in 266 Segment Routing 268 5.1. Stateful PCE Model 270 Active stateful PCE is described in [RFC8231]. PCE as a Central 271 Controller (PCECC) reuses the existing active stateful PCE mechanism 272 as much as possible to control the LSPs. 274 5.2. New LSP Functions 276 Several new functions are required in PCEP to support PCECC as 277 described in [I-D.ietf-pce-pcep-extension-for-pce-controller]. This 278 document reuses the existing messages to support PCECC-SR. 280 The PCEP messages PCRpt, PCInitiate, PCUpd are used to send LSP 281 Reports, LSP setup, and LSP update respectively. The extended 282 PCInitiate message described in 283 [I-D.ietf-pce-pcep-extension-for-pce-controller] is used to download 284 or clean up central controller's instructions (CCIs) (SR SID in the 285 scope of this document). The extended PCRpt message described in 286 [I-D.ietf-pce-pcep-extension-for-pce-controller] is also used to 287 report the CCIs (SR SIDs) from PCC to PCE. 289 [I-D.ietf-pce-pcep-extension-for-pce-controller] specify an object 290 called CCI for the encoding of the central controller's instructions. 291 This document extends the CCI by defining a new object-type for 292 segment routing. The PCEP messages are extended in this document to 293 handle the PCECC operations for SR. 295 5.3. PCECC Capability Advertisement 297 During PCEP Initialization Phase, PCEP Speakers (PCE or PCC) 298 advertise their support of PCECC extensions. A PCEP Speaker includes 299 the "PCECC Capability" sub-TLV, described in 300 [I-D.ietf-pce-pcep-extension-for-pce-controller]. 302 A new S-bit is added in the PCECC-CAPABILITY sub-TLV to indicate 303 support for PCECC-SR. A PCC MUST set the S-bit in the PCECC- 304 CAPABILITY sub-TLV and include the SR-PCE-CAPABILITY sub-TLV 305 ([RFC8664]) in the OPEN Object (inside the PATH-SETUP-TYPE-CAPABILITY 306 TLV) to support the PCECC SR extensions defined in this document. If 307 the S-bit is set in the PCECC-CAPABILITY sub-TLV and the SR-PCE- 308 CAPABILITY sub-TLV is not advertised in the OPEN Object, PCE SHOULD 309 send a PCErr message with Error-Type=19 (Invalid Operation) and 310 Error-value=TBD4 (SR capability was not advertised) and terminate the 311 session. 313 The rest of the processing is as per 314 [I-D.ietf-pce-pcep-extension-for-pce-controller]. 316 5.4. PCEP session IP address and TED Router ID 318 A PCE may construct its Traffic Engineering Database (TED) by 319 participating in the IGP ([RFC3630] and [RFC5305] for MPLS-TE; 320 [RFC4203] and [RFC5307] for GMPLS). An alternative is offered by 321 BGP-LS [RFC7752] and [I-D.dhodylee-pce-pcep-ls]. 323 A PCEP [RFC5440] speaker could use any local IP address while 324 creating a TCP session. It is important to link the session IP 325 address with the Router ID in TED for successful PCECC operations. 327 During PCEP Initialization Phase, the PCC SHOULD advertise the TE 328 mapping information by including the "Node Attributes TLV" 329 [I-D.dhodylee-pce-pcep-ls] with "IPv4/IPv6 Router-ID of Local Node", 330 in the OPEN Object for this purpose. [RFC7752] describes the usage 331 as auxiliary Router-IDs that the IGP might be using, e.g., for TE 332 purposes. If there are more than one auxiliary Router-ID of a given 333 type, then multiple TLVs are used to encode them. 335 If "IPv4/IPv6 Router-ID" TLV is not present, the TCP session IP 336 address is directly used for mapping purpose. 338 5.5. LSP Operations 340 [RFC8664] specify the PCEP extension to allow a stateful PCE to 341 compute and initiate SR-TE paths, as well as a PCC to request a path 342 subject to certain constraint(s) and optimization criteria in SR 343 networks. 345 The Path Setup Type for segment routing (PST=1) is used on the PCEP 346 session with the Ingress as per [RFC8664]. 348 5.5.1. PCECC Segment Routing (SR) 350 Segment Routing (SR) as described in [RFC8402] depends on "segments" 351 that are advertised by Interior Gateway Protocols (IGPs). The SR- 352 node allocates and advertises the SID (node, adj, etc) and flood them 353 via the IGP. This document proposes a new mechanism where PCE 354 allocates the SID (label/index/SID) centrally and uses PCEP to 355 advertise them. In some deployments, PCE (and PCEP) are better 356 suited than IGP because of the centralized nature of PCE and direct 357 TCP based PCEP sessions to the node. 359 5.5.1.1. PCECC SR Node/Prefix SID allocation 361 Each node (PCC) is allocated a node-SID by the PCECC. The PCECC 362 sends PCInitiate message to update the label map of each node to all 363 the nodes in the domain. The TE router ID is determined from the TED 364 or from "IPv4/IPv6 Router-ID" Sub-TLV [I-D.dhodylee-pce-pcep-ls], in 365 the OPEN Object Section 5.4. 367 It is RECOMMENDED that PCEP session with PCECC-SR capability to use a 368 different session IP address during TCP session establishment than 369 the node Router ID in TEDB, to make sure that the PCEP session does 370 not get impacted by the SR Node/Prefix Label maps (Section 5.4). 372 If a node (PCC) receives a PCInitiate message with a CCI encoding a 373 SID, out of the range set aside for the SR Global Block (SRGB), it 374 MUST send a PCErr message with Error-type=TBD (PCECC failure) and 375 Error-value=TBD (Label out of range) (defined in 376 [I-D.ietf-pce-pcep-extension-for-pce-controller]) and MUST include 377 the SRP object to specify the error is for the corresponding central 378 control instruction via the PCInitiate message. 380 On receiving the label map, each node (PCC) uses the local routing 381 information to determine the next-hop and download the label 382 forwarding instructions accordingly. The PCInitiate message in this 383 case does not use the LSP object but uses a new FEC object defined in 384 this document. 386 +---------+ +-------+ 387 |PCC | | PCE | 388 |192.0.2.3| +-------+ 389 +------| | | 390 | PCC +---------+ | 391 | 192.0.2.2| | | 392 +------| | | | 393 |PCC +----------+ | | 394 |192.0.2.1| | | | 395 +---------+ | | | 396 | | | | 397 |<------- PCInitiate, FEC=192.0.2.1---------------- | Label Map 398 | | | CC-ID=X | update 399 |------- PCRpt,CC-ID=X --------------------------->| CCI 400 |Find | | | 401 |Nexthop|<------- PCInitiate, FEC=192.0.2.1-------- | Label Map 402 |locally| | CC-ID=Y | update 403 | |----- PCRpt,CC-ID=Y -------------------->| CCI 404 | | | | 405 | | |<--- PCInitiate, FEC=192.0.2.1---- | Label Map 406 | | | CC-ID=Z | update 407 | | |---- PCRpt,CC-ID=Z -------------->| CCI 408 | | | | 410 The forwarding behavior and the end result is similar to IGP based 411 "Node-SID" in SR. Thus, from anywhere in the domain, it enforces the 412 ECMP-aware shortest-path forwarding of the packet towards the related 413 node as per [RFC8402]. 415 PCE relies on the Node/Prefix Label clean up using the same 416 PCInitiate message as per [RFC8281]. 418 The above example Figure 1 depicts the FEC and PCEP speakers that 419 uses IPv4 address. Similarly an IPv6 address (such as 2001:DB8::1) 420 can be used during PCEP session establishment in the FEC object as 421 described in this specification. 423 In the case where the label/SID allocation is made by the PCC itself 424 (see Section 5.5.1.6), the PCE could request an allocation to be made 425 by the PCC, and where the PCC would send a PCRpt with the allocated 426 label/SID encoded in the CC-ID object as shown in Figure 2. 428 +---------+ +-------+ 429 |PCC | | PCE | 430 |192.0.2.3| +-------+ 431 +------| | | 432 | PCC +---------+ | 433 | 192.0.2.2| | | 434 +------| | | | 435 |PCC +----------+ | | 436 |192.0.2.1| | | | 437 +---------+ | | | 438 | | | | 439 |<------- PCInitiate, FEC=192.0.2.1---------------- | Label Map 440 | | | CC-ID=X,C=1 | request 441 |------- PCRpt,CC-ID=X,Label ---------------------->| CCI 442 |Find | | | 443 |Nexthop|<------- PCInitiate, FEC=192.0.2.1-------- | Label Map 444 |locally| | CC-ID=Y,C=0,Label | update 445 | |----- PCRpt,CC-ID=Y -------------------->| CCI 446 | | | | 447 | | |<--- PCInitiate, FEC=192.0.2.1---- | Label Map 448 | | | CC-ID=Z,C=0,Label | update 449 | | |---- PCRpt,CC-ID=Z -------------->| CCI 450 | | | | 452 It should be noted that in this example, the request is made to the 453 node 192.0.2.1 with C bit set in the CCI object to indicate that the 454 allocation needs to be done by this PCC and it responds with the 455 allocated label/SID to the PCE. The PCE would further inform the 456 other PCCs in the network about the label-map allocation without 457 setting the C bit. 459 5.5.1.2. PCECC SR Adjacency Label allocation 461 For PCECC-SR, apart from node-SID, Adj-SID is used where each 462 adjacency is allocated an Adj-SID by the PCECC. The PCECC sends the 463 PCInitiate message to update the label map of each adjacency to the 464 corresponding nodes in the domain. Each node (PCC) download the 465 label forwarding instructions accordingly. Similar to SR Node/Prefix 466 Label allocation, the PCInitiate message in this case does not use 467 the LSP object but uses the new FEC object defined in this document. 469 +---------+ +-------+ 470 |PCC | | PCE | 471 |192.0.2.3| +-------+ 472 +------| | | 473 | PCC +---------+ | 474 | 192.0.2.2| | | 475 +------| | | | 476 |PCC +----------+ | | 477 |192.0.2.1| | | | 478 +---------+ | | | 479 | | | | 480 |<------ PCInitiate, FEC=198.51.100.1 / --------- | Label Map 481 | | | 198.51.100.2 | update 482 | | | CC-ID=A | CCI 483 |------- PCRpt,CC-ID=A ------------------------->| 484 | | | | 485 | |<----- PCInitiate, FEC=198.51.100.2---- | Label Map 486 | | | 198.51.100.1 | update 487 | | | CC-ID=B | CCI 488 | |----- PCRpt,CC-ID=B ----------------->| 489 | | | | 491 The forwarding behavior and the end result is similar to IGP based 492 "Adj-SID" in SR. 494 PCE relies on the Adj label clean up using the same PCInitiate 495 message as per [RFC8281]. 497 The above example Figure 3 depicts FEC object and PCEP speakers that 498 uses an IPv4 address. Similarly an IPv6 address (such as 499 2001:DB8::1, 2001:DB8::2) can be used during the PCEP session 500 establishment in the FEC object as described in this specification. 502 The handling of adjacencies on the LAN subnetworks is specified in 503 [RFC8402]. PCECC MUST assign Adj-SID for every pair of routers in 504 the LAN. The rest of the protocol mechanism remains the same. 506 In the case where the label/SID map allocation is made by the PCC 507 itself (see Section 5.5.1.6), the PCE could request an allocation to 508 be made by the PCC, and where the PCC would send a PCRpt with the 509 allocated label/SID encoded in the CC-ID object as shown in Figure 4. 511 +---------+ +-------+ 512 |PCC | | PCE | 513 |192.0.2.3| +-------+ 514 +------| | | 515 | PCC +---------+ | 516 | 192.0.2.2| | | 517 +------| | | | 518 |PCC +----------+ | | 519 |192.0.2.1| | | | 520 +---------+ | | | 521 | | | | 522 |<------ PCInitiate, FEC=198.51.100.1------------ | Label Map 523 | | | 198.51.100.2 | request 524 | | | CC-ID=A,C=1 | CCI 525 |------- PCRpt,CC-ID=A,Label1-------------------->| 526 | | | | 527 | |<----- PCInitiate, FEC=198.51.100.2---- | Label Map 528 | | | 198.51.100.1 | request 529 | | | CC-ID=B,C=1 | CCI 530 | |----- PCRpt,CC-ID=B,Label2------------>| 531 | | | | 533 In this example, the request is made to the node 192.0.2.1 with the C 534 bit set in the CCI object to indicate that the allocation needs to be 535 done by this PCC for the adjacency (198.51.100.1 - 198.51.100.2) and 536 it responds with the allocated label/SID to the PCE. Similarly, 537 another request is made to the node 192.0.2.2 with the C bit set in 538 the CCI object to indicate that the allocation needs to be done by 539 this PCC for the adjacency (198.51.100.2 - 198.51.100.1). 541 5.5.1.3. Redundant PCEs 543 [I-D.litkowski-pce-state-sync] describes the synchronization 544 mechanism between the stateful PCEs. The SR SIDs allocated by a PCE 545 MUST also be synchronized among PCEs for PCECC SR state 546 synchronization. Note that the SR SIDs are independent of the SR-TE 547 LSPs, and remains intact till any topology change. The redundant 548 PCEs MUST have a common view of all SR SIDs allocated in the domain. 550 5.5.1.4. Re Delegation and Clean up 552 [I-D.ietf-pce-pcep-extension-for-pce-controller] describes the action 553 needed for CCIs for the static LSPs on a terminated session. Same 554 holds true for the CCI for SR SID as well. 556 5.5.1.5. Synchronization of Label Allocations 558 [I-D.ietf-pce-pcep-extension-for-pce-controller] describes the 559 synchronization of Central Controller's Instructions (CCI) via LSP 560 state synchronization as described in [RFC8231] and [RFC8232]. Same 561 procedures are applied for the CCI for SR SID as well. 563 5.5.1.6. PCC-Based Allocations 565 The PCE can request the PCC to allocate the label/SID using the 566 PCInitiate message. The C flag in the CCI object is set to 1 to 567 indicate that the allocation needs to be done by the PCC. The PCC 568 would allocate the SID/Label/Index and would report to the PCE using 569 the PCRpt message. 571 If the value of the SID/Label/Index is 0 and the C flag is set to 1, 572 it indicates that the PCE is requesting the allocation to be done by 573 the PCC. If the SID/Label/Index is 'n' and the C flag is set to 1 in 574 the CCI object, it indicates that the PCE requests a specific value 575 'n' for the SID/Label/Index. If the allocation is successful, the 576 PCC should report via PCRpt message with the CCI object. Else, it 577 MUST send a PCErr message with Error-Type = TBD ("PCECC failure") and 578 Error Value = TBD ("Invalid CCI") (defined in 579 [I-D.ietf-pce-pcep-extension-for-pce-controller]). If the value of 580 the SID/Label/Index in the CCI object is valid, but the PCC is unable 581 to allocate it, it MUST send a PCErr message with Error-Type = TBD 582 ("PCECC failure") and Error Value = TBD ("Unable to allocate the 583 specified CCI") (defined in 584 [I-D.ietf-pce-pcep-extension-for-pce-controller]). 586 If the PCC wishes to withdraw or modify the previously assigned 587 label/SID, it MUST send a PCRpt message without any SID/Label/Index 588 or with the SID/Label/Index containing the new value respectively in 589 the CCI object. The PCE would further trigger the removal of the 590 central controller instruction as per this document. 592 5.5.1.7. Binding SID 594 A PCECC can allocate and provision the node/prefix/adjacency label 595 (SID) via PCEP. Another SID called binding SID is described in 596 [I-D.ietf-pce-binding-label-sid], the PCECC mechanism can also be 597 used to allocate the binding SID. 599 A procedure for binding label/SID allocation is described in 600 [I-D.ietf-pce-pcep-extension-for-pce-controller] and is applicable 601 for all path setup types (including SR paths). 603 6. PCEP Messages 605 As defined in [RFC5440], a PCEP message consists of a common header 606 followed by a variable-length body made of a set of objects that can 607 be either mandatory or optional. An object is said to be mandatory 608 in a PCEP message when the object must be included for the message to 609 be considered valid. For each PCEP message type, a set of rules is 610 defined that specify the set of objects that the message can carry. 611 An implementation MUST form the PCEP messages using the object 612 ordering specified in this document. 614 6.1. Central Control Instructions 616 6.1.1. The PCInitiate Message 618 The PCInitiate message defined in [RFC8281] and extended in 619 [I-D.ietf-pce-pcep-extension-for-pce-controller] is further extended 620 to support SR based central control instructions. 622 The format of the extended PCInitiate message is as follows: 624 ::= 625 626 Where: 627 is defined in [RFC5440] 629 ::= 630 [] 632 ::= 633 (| 634 | 635 ) 637 ::= 638 ( 639 )| 640 ( 641 ) 643 ::= 644 [] 646 Where: 647 and 648 are as per 649 [RFC8281]. 651 The LSP and SRP object is defined in [RFC8231]. 653 When the PCInitiate message is used to distribute SR SIDs, the SRP, 654 the FEC and the CCI objects MUST be present. The error handling for 655 missing SRP or CCI object is as per 656 [I-D.ietf-pce-pcep-extension-for-pce-controller]. If the FEC object 657 is missing, the receiving PCC MUST send a PCErr message with Error- 658 type=6 (Mandatory Object missing) and Error-value=TBD5 (FEC object 659 missing). 661 To clean up, the R (remove) bit in the SRP object and the 662 corresponding FEC and the CCI object are included. 664 6.1.2. The PCRpt message 666 The PCRpt message can be used to report the SR central controller 667 instructions received from the PCECC during the state synchronization 668 phase or as an acknowledgment to the PCInitiate message. 670 The format of the PCRpt message is as follows: 672 ::= 673 674 Where: 676 ::= [] 678 ::= (| 679 ) 681 ::= [] 682 683 685 ::= [] 686 ( 687 )| 688 ( 689 ) 691 ::= 692 [] 694 Where: 695 is as per [RFC8231] and the LSP and SRP object are 696 also defined in [RFC8231]. 698 When PCRpt message is used to report the label map allocations, the 699 FEC and CCI objects MUST be present. The error handling for the 700 missing CCI object is as per 701 [I-D.ietf-pce-pcep-extension-for-pce-controller]. If the FEC object 702 is missing, the receiving PCE MUST send a PCErr message with Error- 703 type=6 (Mandatory Object missing) and Error-value=TBD5 (FEC object 704 missing). 706 7. PCEP Objects 708 7.1. OPEN Object 710 7.1.1. PCECC Capability sub-TLV 712 [I-D.ietf-pce-pcep-extension-for-pce-controller] defined the PCECC- 713 CAPABILITY sub-TLV. 715 A new S-bit is defined in PCECC-CAPABILITY sub-TLV for PCECC-SR: 717 0 1 2 3 718 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 1 719 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 720 | Type=TBD | Length=4 | 721 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 722 | Flags |S|L| 723 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 725 [Editor's Note - The above figure is included for ease of the reader 726 but should be removed before publication.] 728 S (PCECC-SR-CAPABILITY - 1 bit - TBD1): If set to 1 by a PCEP 729 speaker, it indicates that the PCEP speaker is capable of PCECC-SR 730 capability and the PCE allocates the Node and Adj label/SID on this 731 session. 733 7.2. SR-TE Path Setup 735 The PATH-SETUP-TYPE TLV is defined in [RFC8408]. A PST value of 1 is 736 used when Path is setup via SR mode as per [RFC8664]. The procedure 737 for SR-TE path setup as specified in [RFC8664] remians unchanged. 739 7.3. CCI Object 741 The Central Control Instructions (CCI) Object used by the PCE to 742 specify the controller instructions is defined in 743 [I-D.ietf-pce-pcep-extension-for-pce-controller]. This document 744 defines another object-type for SR-MPLS purpose. 746 CCI Object-Type is TBD6 for SR-MPLS as below - 748 0 1 2 3 749 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 1 750 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 751 | CC-ID | 752 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 753 | MT-ID | Algorithm | Flags |B|P|G|C|N|E|V|L| 754 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 755 // SID/Label/Index (variable) // 756 +---------------------------------------------------------------+ 757 | | 758 // Optional TLV // 759 | | 760 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 761 The field CC-ID is as described in 762 [I-D.ietf-pce-pcep-extension-for-pce-controller]. Following new 763 fields are defined for CCI Object-Type TBD6 - 765 MT-ID: Multi-Topology ID (as defined in [RFC4915]). 767 Algorithm: Single octet identifying the algorithm the SID is 768 associated with. See [RFC8665]. 770 Flags: is used to carry any additional information pertaining to the 771 CCI. The following bits are defined - 773 * L-Bit (Local/Global): If set, then the value/index carried by 774 the CCI object has local significance. If not set, then the 775 value/index carried by this object has global significance. 777 * V-Bit (Value/Index): If set, then the CCI carries an absolute 778 value. If not set, then the CCI carries an index. 780 * E-Bit (Explicit-Null): If set, any upstream neighbor of the 781 node that advertised the SID MUST replace the SID with the 782 Explicit-NULL label (0 for IPv4) before forwarding the packet. 784 * N-Bit (No-PHP): If set, then the penultimate hop MUST NOT pop 785 the SID before delivering packets to the node that advertised 786 the SID. 788 * C-Bit (PCC Allocation): If the bit is set to 1, it indicates 789 that the allocation needs to be done by the PCC for this 790 central controller instruction. A PCE set this bit to request 791 the PCC to make an allocation from its SR label/ID space. A 792 PCC would set this bit to indicate that it has allocated the 793 CC-ID and report it to the PCE. 795 * Following bits are applicable when the SID represents an Adj- 796 SID only, it MUST be ignored for others - 798 + G-Bit (Group): When set, the G-Flag indicates that the Adj- 799 SID refers to a group of adjacencies (and therefore MAY be 800 assigned to other adjacencies as well). 802 + P-Bit (Persistent): When set, the P-Flag indicates that the 803 Adj-SID is persistently allocated, i.e., the Adj-SID value 804 remains consistent across router restart and/or interface 805 flap. 807 + B-Bit (Backup): If set, the Adj-SID refers to an adjacency 808 that is eligible for protection (e.g., using IP Fast Reroute 809 or MPLS-FRR (MPLS-Fast Reroute) as described in Section 2.1 810 of [RFC8402]. 812 + All unassigned bits MUST be set to zero at transmission and 813 ignored at receipt. 815 SID/Label/Index: According to the V and L flags, it contains either: 817 A 32-bit index defining the offset in the SID/Label space 818 advertised by this router. 820 A 24-bit label where the 20 rightmost bits are used for 821 encoding the label value. 823 7.4. FEC Object 825 The FEC Object is used to specify the FEC information and MAY be 826 carried within PCInitiate or PCRpt message. 828 FEC Object-Class is TBD3. 830 FEC Object-Type is 1 'IPv4 Node ID'. 832 0 1 2 3 833 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 1 834 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 835 | IPv4 Node ID | 836 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 838 FEC Object-Type is 2 'IPv6 Node ID'. 840 0 1 2 3 841 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 1 842 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 843 | | 844 // IPv6 Node ID (16 bytes) // 845 | | 846 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 848 FEC Object-Type is 3 'IPv4 Adjacency'. 850 0 1 2 3 851 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 1 852 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 853 | Local IPv4 address | 854 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 855 | Remote IPv4 address | 856 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 858 FEC Object-Type is 4 'IPv6 Adjacency'. 860 0 1 2 3 861 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 1 862 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 863 | | 864 // Local IPv6 address (16 bytes) // 865 | | 866 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 867 | | 868 // Remote IPv6 address (16 bytes) // 869 | | 870 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 872 FEC Object-Type is 5 'Unnumbered Adjacency with IPv4 NodeIDs'. 874 0 1 2 3 875 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 1 876 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 877 | Local Node-ID | 878 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 879 | Local Interface ID | 880 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 881 | Remote Node-ID | 882 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 883 | Remote Interface ID | 884 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 886 FEC Object-Type is 6 'Linklocal IPv6 Adjacency'. 888 0 1 2 3 889 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 1 890 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 891 // Local IPv6 address (16 octets) // 892 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 893 | Local Interface ID | 894 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 895 // Remote IPv6 address (16 octets) // 896 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 897 | Remote Interface ID | 898 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 900 The FEC objects are as follows: 902 IPv4 Node ID: where IPv4 Node ID is specified as an IPv4 address of 903 the Node. FEC Object-type is 1, and the Object-Length is 4 in this 904 case. 906 IPv6 Node ID: where IPv6 Node ID is specified as an IPv6 address of 907 the Node. FEC Object-type is 2, and the Object-Length is 16 in this 908 case. 910 IPv4 Adjacency: where Local and Remote IPv4 address is specified as 911 pair of IPv4 addresses of the adjacency. FEC Object-type is 3, and 912 the Object-Length is 8 in this case. 914 IPv6 Adjacency: where Local and Remote IPv6 address is specified as 915 pair of IPv6 addresses of the adjacency. FEC Object-type is 4, and 916 the Object-Length is 32 in this case. 918 Unnumbered Adjacency with IPv4 NodeID: where a pair of Node ID / 919 Interface ID tuple is used. FEC Object-type is 5, and the Object- 920 Length is 16 in this case. 922 Linklocal IPv6 Adjacency: where a pair of (global IPv6 address, 923 interface ID) tuple is used. FEC object-type is 6, and the Object- 924 Length is 40 in this case. 926 8. Implementation Status 928 [Note to the RFC Editor - remove this section before publication, as 929 well as remove the reference to RFC 7942.] 931 This section records the status of known implementations of the 932 protocol defined by this specification at the time of posting of this 933 Internet-Draft, and is based on a proposal described in [RFC7942]. 934 The description of implementations in this section is intended to 935 assist the IETF in its decision processes in progressing drafts to 936 RFCs. Please note that the listing of any individual implementation 937 here does not imply endorsement by the IETF. Furthermore, no effort 938 has been spent to verify the information presented here that was 939 supplied by IETF contributors. This is not intended as, and must not 940 be construed to be, a catalog of available implementations or their 941 features. Readers are advised to note that other implementations may 942 exist. 944 According to [RFC7942], "this will allow reviewers and working groups 945 to assign due consideration to documents that have the benefit of 946 running code, which may serve as evidence of valuable experimentation 947 and feedback that have made the implemented protocols more mature. 949 It is up to the individual working groups to use this information as 950 they see fit". 952 8.1. Huawei's Proof of Concept based on ONOS 954 The PCE function was developed in the ONOS open source platform. 955 This extension was implemented on a private version as a proof of 956 concept for PCECC. 958 o Organization: Huawei 960 o Implementation: Huawei's PoC based on ONOS 962 o Description: PCEP as a southbound plugin was added to ONOS. To 963 support PCECC-SR, an earlier version of this I-D was implemented. 964 Refer https://wiki.onosproject.org/display/ONOS/PCEP+Protocol 966 o Maturity Level: Prototype 968 o Coverage: Partial 970 o Contact: satishk@huawei.com 972 9. Security Considerations 974 The security considerations described in 975 [I-D.ietf-pce-pcep-extension-for-pce-controller] apply to the 976 extensions described in this document. 978 As per [RFC8231], it is RECOMMENDED that these PCEP extensions only 979 be activated on authenticated and encrypted sessions across PCEs and 980 PCCs belonging to the same administrative authority, using Transport 981 Layer Security (TLS) [RFC8253] as per the recommendations and best 982 current practices in [RFC7525] (unless explicitly set aside in 983 [RFC8253]). 985 10. Manageability Considerations 987 10.1. Control of Function and Policy 989 A PCE or PCC implementation SHOULD allow to configure to enable/ 990 disable PCECC SR capability as a global configuration. The 991 implementation SHOULD also allow setting the local IP address used by 992 the PCEP session. 994 10.2. Information and Data Models 996 [RFC7420] describes the PCEP MIB, this MIB can be extended to get the 997 PCECC SR capability status. 999 The PCEP YANG module [I-D.ietf-pce-pcep-yang] could be extended to 1000 enable/disable PCECC SR capability. 1002 10.3. Liveness Detection and Monitoring 1004 Mechanisms defined in this document do not imply any new liveness 1005 detection and monitoring requirements in addition to those already 1006 listed in [RFC5440]. 1008 10.4. Verify Correct Operations 1010 Mechanisms defined in this document do not imply any new operation 1011 verification requirements in addition to those already listed in 1012 [RFC5440] and [RFC8231]. 1014 10.5. Requirements On Other Protocols 1016 PCEP extensions defined in this document do not put new requirements 1017 on other protocols. 1019 10.6. Impact On Network Operations 1021 PCEP implementation SHOULD allow a limit to be placed on the rate of 1022 PCLabelUpd messages sent by PCE and processed by PCC. It SHOULD also 1023 allow sending a notification when a rate threshold is reached. 1025 11. IANA Considerations 1027 11.1. PCECC-CAPABILITY sub-TLV 1029 [I-D.ietf-pce-pcep-extension-for-pce-controller] defines the PCECC- 1030 CAPABILITY sub-TLV and requests that IANA to create a new sub- 1031 registry to manage the value of the PCECC-CAPABILITY sub-TLV's Flag 1032 field. 1034 IANA is requested to allocate a new bit in the PCECC-CAPABILITY sub- 1035 TLV Flag Field sub-registry, as follows: 1037 Bit Description Reference 1038 TBD1 SR This document 1040 11.2. PCEP Object 1042 IANA is requested to allocate new code-points for the new FEC object 1043 and a new Object-Type for CCI object in "PCEP Objects" sub-registry 1044 as follows: 1046 Object-Class Name Object-Type Reference 1047 Value 1048 TBD3 FEC 1: IPv4 Node ID This document 1049 2: IPv6 Node ID This document 1050 3: IPv4 Adjacency This document 1051 4: IPv6 Adjacency This document 1052 5: Unnumbered Adjacency with This document 1053 IPv4 NodeID 1054 6: Linklocal IPv6 Adjacency This document 1055 TBD CCI 1056 TBD6: SR-MPLS This document 1058 11.3. PCEP-Error Object 1060 IANA is requested to allocate a new error-value within the "PCEP- 1061 ERROR Object Error Types and Values" sub-registry of the PCEP Numbers 1062 registry for the following errors: 1064 Error-Type Meaning 1065 ---------- ------- 1066 6 Mandatory Object missing. 1068 Error-value = TBD5 : FEC object missing 1069 19 Invalid operation. 1071 Error-value = TBD4 : SR capability was 1072 not advertised 1074 11.4. CCI Object Flag Field for SR 1076 IANA is requested to create a new sub-registry to manage the Flag 1077 field of the CCI Object-Type=TBD6 for SR called "CCI Object Flag 1078 Field for SR". New values are to be assigned by Standards Action 1079 [RFC8126]. Each bit should be tracked with the following qualities: 1081 o Bit number (counting from bit 0 as the most significant bit) 1082 o Capability description 1083 o Defining RFC 1085 Following bits are defined for the CCI Object flag field for SR in 1086 this document as follows: 1088 Bit Description Reference 1089 0-7 Unassigned This document 1090 8 B-Bit - Backup This document 1091 9 P-Bit - Persistent This document 1092 10 G-Bit - Group This document 1093 11 C-Bit - PCC Allocation This document 1094 12 N-Bit - No-PHP This document 1095 13 E-Bit - Explicit-Null This document 1096 14 V-Bit - Value/Index This document 1097 15 L-Bit - Local/Global This document 1099 12. Acknowledgments 1101 We would like to thank Robert Tao, Changjing Yan, Tieying Huang and 1102 Avantika for their useful comments and suggestions. 1104 13. References 1106 13.1. Normative References 1108 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1109 Requirement Levels", BCP 14, RFC 2119, 1110 DOI 10.17487/RFC2119, March 1997, 1111 . 1113 [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering 1114 (TE) Extensions to OSPF Version 2", RFC 3630, 1115 DOI 10.17487/RFC3630, September 2003, 1116 . 1118 [RFC4203] Kompella, K., Ed. and Y. Rekhter, Ed., "OSPF Extensions in 1119 Support of Generalized Multi-Protocol Label Switching 1120 (GMPLS)", RFC 4203, DOI 10.17487/RFC4203, October 2005, 1121 . 1123 [RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P. 1124 Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF", 1125 RFC 4915, DOI 10.17487/RFC4915, June 2007, 1126 . 1128 [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic 1129 Engineering", RFC 5305, DOI 10.17487/RFC5305, October 1130 2008, . 1132 [RFC5307] Kompella, K., Ed. and Y. Rekhter, Ed., "IS-IS Extensions 1133 in Support of Generalized Multi-Protocol Label Switching 1134 (GMPLS)", RFC 5307, DOI 10.17487/RFC5307, October 2008, 1135 . 1137 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 1138 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 1139 DOI 10.17487/RFC5440, March 2009, 1140 . 1142 [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and 1143 S. Ray, "North-Bound Distribution of Link-State and 1144 Traffic Engineering (TE) Information Using BGP", RFC 7752, 1145 DOI 10.17487/RFC7752, March 2016, 1146 . 1148 [RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running 1149 Code: The Implementation Status Section", BCP 205, 1150 RFC 7942, DOI 10.17487/RFC7942, July 2016, 1151 . 1153 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 1154 Writing an IANA Considerations Section in RFCs", BCP 26, 1155 RFC 8126, DOI 10.17487/RFC8126, June 2017, 1156 . 1158 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1159 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1160 May 2017, . 1162 [RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path 1163 Computation Element Communication Protocol (PCEP) 1164 Extensions for Stateful PCE", RFC 8231, 1165 DOI 10.17487/RFC8231, September 2017, 1166 . 1168 [RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody, 1169 "PCEPS: Usage of TLS to Provide a Secure Transport for the 1170 Path Computation Element Communication Protocol (PCEP)", 1171 RFC 8253, DOI 10.17487/RFC8253, October 2017, 1172 . 1174 [RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path 1175 Computation Element Communication Protocol (PCEP) 1176 Extensions for PCE-Initiated LSP Setup in a Stateful PCE 1177 Model", RFC 8281, DOI 10.17487/RFC8281, December 2017, 1178 . 1180 [RFC8408] Sivabalan, S., Tantsura, J., Minei, I., Varga, R., and J. 1181 Hardwick, "Conveying Path Setup Type in PCE Communication 1182 Protocol (PCEP) Messages", RFC 8408, DOI 10.17487/RFC8408, 1183 July 2018, . 1185 [RFC8664] Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W., 1186 and J. Hardwick, "Path Computation Element Communication 1187 Protocol (PCEP) Extensions for Segment Routing", RFC 8664, 1188 DOI 10.17487/RFC8664, December 2019, 1189 . 1191 [I-D.ietf-pce-pcep-extension-for-pce-controller] 1192 Li, Z., Peng, S., Negi, M., Zhao, Q., and C. Zhou, "PCEP 1193 Procedures and Protocol Extensions for Using PCE as a 1194 Central Controller (PCECC) of LSPs", draft-ietf-pce-pcep- 1195 extension-for-pce-controller-07 (work in progress), 1196 September 2020. 1198 13.2. Informative References 1200 [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol 1201 Label Switching Architecture", RFC 3031, 1202 DOI 10.17487/RFC3031, January 2001, 1203 . 1205 [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation 1206 Element (PCE)-Based Architecture", RFC 4655, 1207 DOI 10.17487/RFC4655, August 2006, 1208 . 1210 [RFC7025] Otani, T., Ogaki, K., Caviglia, D., Zhang, F., and C. 1211 Margaria, "Requirements for GMPLS Applications of PCE", 1212 RFC 7025, DOI 10.17487/RFC7025, September 2013, 1213 . 1215 [RFC7399] Farrel, A. and D. King, "Unanswered Questions in the Path 1216 Computation Element Architecture", RFC 7399, 1217 DOI 10.17487/RFC7399, October 2014, 1218 . 1220 [RFC7420] Koushik, A., Stephan, E., Zhao, Q., King, D., and J. 1221 Hardwick, "Path Computation Element Communication Protocol 1222 (PCEP) Management Information Base (MIB) Module", 1223 RFC 7420, DOI 10.17487/RFC7420, December 2014, 1224 . 1226 [RFC7491] King, D. and A. Farrel, "A PCE-Based Architecture for 1227 Application-Based Network Operations", RFC 7491, 1228 DOI 10.17487/RFC7491, March 2015, 1229 . 1231 [RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre, 1232 "Recommendations for Secure Use of Transport Layer 1233 Security (TLS) and Datagram Transport Layer Security 1234 (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May 1235 2015, . 1237 [RFC8232] Crabbe, E., Minei, I., Medved, J., Varga, R., Zhang, X., 1238 and D. Dhody, "Optimizations of Label Switched Path State 1239 Synchronization Procedures for a Stateful PCE", RFC 8232, 1240 DOI 10.17487/RFC8232, September 2017, 1241 . 1243 [RFC8283] Farrel, A., Ed., Zhao, Q., Ed., Li, Z., and C. Zhou, "An 1244 Architecture for Use of PCE and the PCE Communication 1245 Protocol (PCEP) in a Network with Central Control", 1246 RFC 8283, DOI 10.17487/RFC8283, December 2017, 1247 . 1249 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 1250 Decraene, B., Litkowski, S., and R. Shakir, "Segment 1251 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 1252 July 2018, . 1254 [RFC8660] Bashandy, A., Ed., Filsfils, C., Ed., Previdi, S., 1255 Decraene, B., Litkowski, S., and R. Shakir, "Segment 1256 Routing with the MPLS Data Plane", RFC 8660, 1257 DOI 10.17487/RFC8660, December 2019, 1258 . 1260 [RFC8665] Psenak, P., Ed., Previdi, S., Ed., Filsfils, C., Gredler, 1261 H., Shakir, R., Henderickx, W., and J. Tantsura, "OSPF 1262 Extensions for Segment Routing", RFC 8665, 1263 DOI 10.17487/RFC8665, December 2019, 1264 . 1266 [RFC8667] Previdi, S., Ed., Ginsberg, L., Ed., Filsfils, C., 1267 Bashandy, A., Gredler, H., and B. Decraene, "IS-IS 1268 Extensions for Segment Routing", RFC 8667, 1269 DOI 10.17487/RFC8667, December 2019, 1270 . 1272 [I-D.ietf-teas-pcecc-use-cases] 1273 Li, Z., Khasanov, B., Dhody, D., Zhao, Q., Ke, Z., Fang, 1274 L., Zhou, C., Communications, T., Rachitskiy, A., and A. 1275 Gulida, "The Use Cases for Path Computation Element (PCE) 1276 as a Central Controller (PCECC).", draft-ietf-teas-pcecc- 1277 use-cases-06 (work in progress), September 2020. 1279 [I-D.ietf-pce-pcep-yang] 1280 Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A 1281 YANG Data Model for Path Computation Element 1282 Communications Protocol (PCEP)", draft-ietf-pce-pcep- 1283 yang-14 (work in progress), July 2020. 1285 [I-D.ietf-pce-binding-label-sid] 1286 Filsfils, C., Sivabalan, S., Tantsura, J., Hardwick, J., 1287 Previdi, S., and C. Li, "Carrying Binding Label/Segment-ID 1288 in PCE-based Networks.", draft-ietf-pce-binding-label- 1289 sid-03 (work in progress), June 2020. 1291 [I-D.litkowski-pce-state-sync] 1292 Litkowski, S., Sivabalan, S., Li, C., and H. Zheng, "Inter 1293 Stateful Path Computation Element (PCE) Communication 1294 Procedures.", draft-litkowski-pce-state-sync-08 (work in 1295 progress), July 2020. 1297 [I-D.dhodylee-pce-pcep-ls] 1298 Dhody, D., Peng, S., Lee, Y., Ceccarelli, D., and A. Wang, 1299 "PCEP extensions for Distribution of Link-State and TE 1300 Information", draft-dhodylee-pce-pcep-ls-17 (work in 1301 progress), July 2020. 1303 [I-D.dhody-pce-pcep-extension-pce-controller-srv6] 1304 Li, Z., Peng, S., Geng, X., and M. Negi, "PCEP Procedures 1305 and Protocol Extensions for Using PCE as a Central 1306 Controller (PCECC) for SRv6", draft-dhody-pce-pcep- 1307 extension-pce-controller-srv6-04 (work in progress), July 1308 2020. 1310 Appendix A. Contributor Addresses 1312 Dhruv Dhody 1313 Huawei Technologies 1314 Divyashree Techno Park, Whitefield 1315 Bangalore, Karnataka 560066 1316 India 1318 EMail: dhruv.ietf@gmail.com 1320 Satish Karunanithi 1321 Huawei Technologies 1322 Divyashree Techno Park, Whitefield 1323 Bangalore, Karnataka 560066 1324 India 1326 EMail: satishk@huawei.com 1328 Adrian Farrel 1329 Juniper Networks, Inc 1330 UK 1332 EMail: adrian@olddog.co.uk 1334 Xuesong Geng 1335 Huawei Technologies 1336 China 1338 Email: gengxuesong@huawei.com 1340 Udayasree Palle 1342 EMail: udayasreereddy@gmail.com 1344 Katherine Zhao 1345 Huawei Technologies 1346 2330 Central Expressway 1347 Santa Clara, CA 95050 1348 USA 1350 EMail: katherine.zhao@huawei.com 1352 Boris Zhang 1353 Telus Ltd. 1354 Toronto 1355 Canada 1357 EMail: boris.zhang@telus.com 1358 Alex Tokar 1359 Cisco Systems 1360 Slovak Republic 1362 EMail: atokar@cisco.com 1364 Authors' Addresses 1366 Zhenbin Li 1367 Huawei Technologies 1368 Huawei Bld., No.156 Beiqing Rd. 1369 Beijing 100095 1370 China 1372 EMail: lizhenbin@huawei.com 1374 Shuping Peng 1375 Huawei Technologies 1376 Huawei Bld., No.156 Beiqing Rd. 1377 Beijing 100095 1378 China 1380 EMail: pengshuping@huawei.com 1382 Mahendra Singh Negi 1383 RtBrick Inc 1384 N-17L, 18th Cross Rd, HSR Layout 1385 Bangalore, Karnataka 560102 1386 India 1388 EMail: mahend.ietf@gmail.com 1390 Quintin Zhao 1391 Etheric Networks 1392 1009 S CLAREMONT ST 1393 SAN MATEO, CA 94402 1394 USA 1396 EMail: qzhao@ethericnetworks.com 1397 Chao Zhou 1398 HPE 1400 EMail: chaozhou_us@yahoo.com