idnits 2.17.1 draft-ietf-pce-pcep-extension-pce-controller-sr-01.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (February 21, 2021) is 1159 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 7752 (Obsoleted by RFC 9552) == Outdated reference: A later version (-14) exists of draft-ietf-pce-pcep-extension-for-pce-controller-10 == Outdated reference: A later version (-27) exists of draft-dhodylee-pce-pcep-ls-19 ** Downref: Normative reference to an Experimental draft: draft-dhodylee-pce-pcep-ls (ref. 'I-D.dhodylee-pce-pcep-ls') -- Obsolete informational reference (is this intentional?): RFC 7525 (Obsoleted by RFC 9325) == Outdated reference: A later version (-13) exists of draft-ietf-teas-pcecc-use-cases-06 == Outdated reference: A later version (-23) exists of draft-ietf-pce-pcep-yang-15 == Outdated reference: A later version (-16) exists of draft-ietf-pce-binding-label-sid-05 == Outdated reference: A later version (-10) exists of draft-litkowski-pce-state-sync-09 == Outdated reference: A later version (-10) exists of draft-dhody-pce-pcep-extension-pce-controller-srv6-05 == Outdated reference: A later version (-16) exists of draft-li-pce-controlled-id-space-07 Summary: 2 errors (**), 0 flaws (~~), 9 warnings (==), 2 comments (--). 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: August 25, 2021 M. Negi 6 RtBrick Inc 7 Q. Zhao 8 Etheric Networks 9 C. Zhou 10 HPE 11 February 21, 2021 13 PCEP Procedures and Protocol Extensions for Using PCE as a Central 14 Controller (PCECC) for Segment Routing (SR) MPLS Segment Identifier 15 (SID) Allocation and Distribution. 16 draft-ietf-pce-pcep-extension-pce-controller-sr-01 18 Abstract 20 The Path Computation Element (PCE) is a core component of Software- 21 Defined Networking (SDN) systems. It can compute optimal paths for 22 traffic across a network and can also update the paths to reflect 23 changes in the network or traffic demands. 25 PCE was developed to derive paths for MPLS Label Switched Paths 26 (LSPs), which are supplied to the head end of the LSP using the Path 27 Computation Element Communication Protocol (PCEP). But SDN has a 28 broader applicability than signaled (G)MPLS traffic-engineered (TE) 29 networks, and the PCE may be used to determine paths in a range of 30 use cases. PCEP has been proposed as a control protocol for use in 31 these environments to allow the PCE to be fully enabled as a central 32 controller. 34 A PCE-based Central Controller (PCECC) can simplify the processing of 35 a distributed control plane by blending it with elements of SDN and 36 without necessarily completely replacing it. Thus, the LSP can be 37 calculated/set up/initiated and the label forwarding entries can also 38 be downloaded through a centralized PCE server to each network device 39 along the path while leveraging the existing PCE technologies as much 40 as possible. 42 This document specifies the procedures and PCEP extensions when a 43 PCE-based controller is also responsible for configuring the 44 forwarding actions on the routers, in addition to computing the paths 45 for packet flows in a segment routing (SR) network and telling the 46 edge routers what instructions to attach to packets as they enter the 47 network. PCECC is further enhanced for SR-MPLS SID (Segment 48 Identifier) allocation and distribution. 50 Status of This Memo 52 This Internet-Draft is submitted in full conformance with the 53 provisions of BCP 78 and BCP 79. 55 Internet-Drafts are working documents of the Internet Engineering 56 Task Force (IETF). Note that other groups may also distribute 57 working documents as Internet-Drafts. The list of current Internet- 58 Drafts is at https://datatracker.ietf.org/drafts/current/. 60 Internet-Drafts are draft documents valid for a maximum of six months 61 and may be updated, replaced, or obsoleted by other documents at any 62 time. It is inappropriate to use Internet-Drafts as reference 63 material or to cite them other than as "work in progress." 65 This Internet-Draft will expire on August 25, 2021. 67 Copyright Notice 69 Copyright (c) 2021 IETF Trust and the persons identified as the 70 document authors. All rights reserved. 72 This document is subject to BCP 78 and the IETF Trust's Legal 73 Provisions Relating to IETF Documents 74 (https://trustee.ietf.org/license-info) in effect on the date of 75 publication of this document. Please review these documents 76 carefully, as they describe your rights and restrictions with respect 77 to this document. Code Components extracted from this document must 78 include Simplified BSD License text as described in Section 4.e of 79 the Trust Legal Provisions and are provided without warranty as 80 described in the Simplified BSD License. 82 Table of Contents 84 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 85 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 5 86 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 87 3. PCECC SR-MPLS . . . . . . . . . . . . . . . . . . . . . . . . 5 88 4. PCEP Requirements . . . . . . . . . . . . . . . . . . . . . . 6 89 5. Procedures for Using the PCE as a Central Controller (PCECC) 90 in Segment Routing . . . . . . . . . . . . . . . . . . . . . 7 91 5.1. Stateful PCE Model . . . . . . . . . . . . . . . . . . . 7 92 5.2. New LSP Functions . . . . . . . . . . . . . . . . . . . . 7 93 5.3. PCECC Capability Advertisement . . . . . . . . . . . . . 7 94 5.4. PCEP session IP address and TED Router ID . . . . . . . . 8 95 5.5. LSP Operations . . . . . . . . . . . . . . . . . . . . . 8 96 5.5.1. PCECC Segment Routing (SR) . . . . . . . . . . . . . 8 97 5.5.1.1. PCECC SR Node/Prefix SID allocation . . . . . . . 9 98 5.5.1.2. PCECC SR Adjacency Label allocation . . . . . . . 11 99 5.5.1.3. Redundant PCEs . . . . . . . . . . . . . . . . . 13 100 5.5.1.4. Re Delegation and Clean up . . . . . . . . . . . 13 101 5.5.1.5. Synchronization of Label Allocations . . . . . . 14 102 5.5.1.6. PCC-Based Allocations . . . . . . . . . . . . . . 14 103 5.5.1.7. Binding SID . . . . . . . . . . . . . . . . . . . 14 104 6. PCEP Messages . . . . . . . . . . . . . . . . . . . . . . . . 15 105 6.1. Central Control Instructions . . . . . . . . . . . . . . 15 106 6.1.1. The PCInitiate Message . . . . . . . . . . . . . . . 15 107 6.1.2. The PCRpt message . . . . . . . . . . . . . . . . . . 16 108 7. PCEP Objects . . . . . . . . . . . . . . . . . . . . . . . . 17 109 7.1. OPEN Object . . . . . . . . . . . . . . . . . . . . . . . 17 110 7.1.1. PCECC Capability sub-TLV . . . . . . . . . . . . . . 17 111 7.2. SR-TE Path Setup . . . . . . . . . . . . . . . . . . . . 18 112 7.3. CCI Object . . . . . . . . . . . . . . . . . . . . . . . 18 113 7.4. FEC Object . . . . . . . . . . . . . . . . . . . . . . . 20 114 8. Implementation Status . . . . . . . . . . . . . . . . . . . . 22 115 8.1. Huawei's Proof of Concept based on ONOS . . . . . . . . . 23 116 9. Security Considerations . . . . . . . . . . . . . . . . . . . 23 117 10. Manageability Considerations . . . . . . . . . . . . . . . . 24 118 10.1. Control of Function and Policy . . . . . . . . . . . . . 24 119 10.2. Information and Data Models . . . . . . . . . . . . . . 24 120 10.3. Liveness Detection and Monitoring . . . . . . . . . . . 24 121 10.4. Verify Correct Operations . . . . . . . . . . . . . . . 24 122 10.5. Requirements On Other Protocols . . . . . . . . . . . . 24 123 10.6. Impact On Network Operations . . . . . . . . . . . . . . 24 124 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24 125 11.1. PCECC-CAPABILITY sub-TLV . . . . . . . . . . . . . . . . 24 126 11.2. PCEP Object . . . . . . . . . . . . . . . . . . . . . . 25 127 11.3. PCEP-Error Object . . . . . . . . . . . . . . . . . . . 25 128 11.4. CCI Object Flag Field for SR . . . . . . . . . . . . . . 26 129 12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 26 130 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 27 131 13.1. Normative References . . . . . . . . . . . . . . . . . . 27 132 13.2. Informative References . . . . . . . . . . . . . . . . . 29 133 Appendix A. Contributor Addresses . . . . . . . . . . . . . . . 32 134 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 33 136 1. Introduction 138 The Path Computation Element (PCE) [RFC4655] was developed to offload 139 the path computation function from routers in an MPLS traffic- 140 engineered network. Since then, the role and function of the PCE has 141 grown to cover a number of other uses (such as GMPLS [RFC7025]) and 142 to allow delegated control [RFC8231] and PCE-initiated use of network 143 resources [RFC8281]. 145 According to [RFC7399], Software-Defined Networking (SDN) refers to a 146 separation between the control elements and the forwarding components 147 so that software running in a centralized system, called a 148 controller, can act to program the devices in the network to behave 149 in specific ways. A required element in an SDN architecture is a 150 component that plans how the network resources will be used and how 151 the devices will be programmed. It is possible to view this 152 component as performing specific computations to place traffic flows 153 within the network given knowledge of the availability of network 154 resources, how other forwarding devices are programmed, and the way 155 that other flows are routed. This is the function and purpose of a 156 PCE, and the way that a PCE integrates into a wider network control 157 system (including an SDN system) is presented in [RFC7491]. 159 In early PCE implementations, where the PCE was used to derive paths 160 for MPLS Label Switched Paths (LSPs), paths were requested by network 161 elements (known as Path Computation Clients (PCCs)), and the results 162 of the path computations were supplied to network elements using the 163 Path Computation Element Communication Protocol (PCEP) [RFC5440]. 164 This protocol was later extended to allow a PCE to send unsolicited 165 requests to the network for LSP establishment [RFC8281]. 167 [RFC8283] introduces the architecture for PCE as a central controller 168 as an extension of the architecture described in [RFC4655] and 169 assumes the continued use of PCEP as the protocol used between PCE 170 and PCC. [RFC8283] further examines the motivations and 171 applicability for PCEP as a Southbound Interface (SBI), and 172 introduces the implications for the protocol. 173 [I-D.ietf-teas-pcecc-use-cases] describes the use cases for the PCE- 174 based Central Controller (PCECC) architecture. As described in 175 [RFC8283], PCECC simplifies the processing of a distributed IGP based 176 control plane by blending it with elements of SDN, without replacing 177 it. 179 [I-D.ietf-pce-pcep-extension-for-pce-controller] specify the 180 procedures and PCEP extensions for using the PCE as the central 181 controller for static LSPs, where LSPs can be provisioned as explicit 182 label instructions at each hop on the end-to-end path. 184 Segment Routing (SR) technology leverages the source routing and 185 tunneling paradigms. A source node can choose a path without relying 186 on hop-by-hop signaling protocols such as LDP or RSVP-TE. Each path 187 is specified as a set of "segments" advertised by link-state routing 188 protocols (IS-IS or OSPF). [RFC8402] provides an introduction to SR 189 architecture. The corresponding IS-IS and OSPF extensions are 190 specified in [RFC8667] and [RFC8665] , respectively. It relies on a 191 series of forwarding instructions being placed in the header of a 192 packet. The segment routing architecture supports operations that 193 can be used to steer packet flows in a network, thus providing a form 194 of traffic engineering. [RFC8664] specify the SR specific PCEP 195 extensions. 197 PCECC may further use PCEP for SR SID (Segment Identifier) allocation 198 and distribution to all the SR nodes with some benefits. The SR 199 nodes continue to rely on IGP for distributed computation (nexthop 200 selection, protection etc) where PCE (and PCEP) does only the 201 allocation and distribution of SIDs in the network. Note that the 202 topology at PCE is still learned via existing mechanisms. 204 This document specifies the procedures and PCEP extensions when a 205 PCE-based controller is also responsible for configuring the 206 forwarding actions on the routers (i.e. the SR SID allocation and 207 distribution in this case), in addition to computing the SR paths for 208 packet flows in a segment routing network and telling the edge 209 routers what instructions to attach to packets as they enter the 210 network as described in [RFC8283]. 212 Only SR using MPLS dataplane (SR-MPLS) is in the scope of this 213 document. Refer [I-D.dhody-pce-pcep-extension-pce-controller-srv6] 214 for use of PCECC technique for SR in IPv6 (SRv6) dataplane. 216 1.1. Requirements Language 218 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 219 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 220 "OPTIONAL" in this document are to be interpreted as described in BCP 221 14 [RFC2119] [RFC8174] when, and only when, they appear in all 222 capitals, as shown here. 224 2. Terminology 226 Terminologies used in this document is the same as described in the 227 draft [RFC8283] and [I-D.ietf-teas-pcecc-use-cases]. 229 3. PCECC SR-MPLS 231 [RFC8664] specifies extensions to PCEP that allow a stateful PCE to 232 compute, update, or initiate SR-TE paths. An ingress node of an SR- 233 TE path appends all outgoing packets with a list of MPLS labels 234 (SIDs). This is encoded in SR-ERO subobject, capable of carrying a 235 label (SID) as well as the identity of the node/adjacency label 236 (SID). 238 The notion of segment and SID is defined in [RFC8402], which fits the 239 MPLS architecture [RFC3031] as the label which is managed by a local 240 allocation process of LSR (similarly to other MPLS signaling 241 protocols) [RFC8660]. The SR information such as node/adjacency 242 label (SID) is flooded via IGP as specified in [RFC8667] and 243 [RFC8665]. 245 [RFC8283] examines the motivations and applicability for PCECC and 246 use of PCEP as an SBI. Section 3.1.5. of [RFC8283] highlights the 247 use of PCECC for configuring the forwarding actions on the routers 248 and assume responsibility for managing the label space. It 249 simplifies the processing of a distributed control plane by blending 250 it with elements of SDN and without necessarily completely replacing 251 it. This allows the operator to introduce the advantages of SDN 252 (such as programmability) into the network. Further Section 3.3. of 253 [I-D.ietf-teas-pcecc-use-cases] describes some of the scenarios where 254 the PCECC technique could be useful. Section 4 of [RFC8283] also 255 describe the implications on the protocol when used as an SDN SBI. 256 The operator needs to evaluate the advantages offered by PCECC 257 against the operational and scalability needs of the PCECC. 259 Thus, PCE as a central controller can allocate and provision the 260 node/prefix/adjacency label (SID) via PCEP. The rest of the 261 processing is similar to existing stateful PCE with SR mechanism. 263 For the purpose of this document, it is assumed that the label/SID 264 range to be used by a PCE is set on both PCEP peers. The PCC MUST 265 NOT make allocations from the label space set aside for the PCE to 266 avoid overlap and collisions of label allocations. Further, a global 267 label/SID range is assumed to be set on all PCEP peers in the SR 268 domain. A future extension could add the capability to advertise 269 this range via a possible PCEP extension as well (see 270 [I-D.li-pce-controlled-id-space]). This document also allows a case 271 where the label/SID space is maintained by PCC itself, and the 272 labels/SID are allocated by the PCC, in this case, the PCE should 273 request the allocation from PCC as described in Section 5.5.1.6. 275 4. PCEP Requirements 277 Following key requirements for PCECC-SR should be considered when` 278 designing the PCECC-based solution: 280 o A PCEP speaker supporting this draft needs to have the capability 281 to advertise its PCECC-SR capability to its peers. 283 o PCEP procedures need to allow for PCC-based label/SID allocations. 285 o PCEP procedures need means to update (or clean up) the label-map 286 entry to the PCC. 288 o PCEP procedures need to provide a mean to synchronize the SR 289 labels/SIDs allocations between the PCE to the PCC via PCEP 290 messages. 292 5. Procedures for Using the PCE as a Central Controller (PCECC) in 293 Segment Routing 295 5.1. Stateful PCE Model 297 Active stateful PCE is described in [RFC8231]. PCE as a Central 298 Controller (PCECC) reuses the existing active stateful PCE mechanism 299 as much as possible to control the LSPs. 301 5.2. New LSP Functions 303 Several new functions are required in PCEP to support PCECC as 304 described in [I-D.ietf-pce-pcep-extension-for-pce-controller]. This 305 document reuses the existing messages to support PCECC-SR. 307 The PCEP messages PCRpt, PCInitiate, PCUpd are used to send LSP 308 Reports, LSP setup, and LSP update respectively. The extended 309 PCInitiate message described in 310 [I-D.ietf-pce-pcep-extension-for-pce-controller] is used to download 311 or clean up central controller's instructions (CCIs) (SR SID in the 312 scope of this document). The extended PCRpt message described in 313 [I-D.ietf-pce-pcep-extension-for-pce-controller] is also used to 314 report the CCIs (SR SIDs) from PCC to PCE. 316 [I-D.ietf-pce-pcep-extension-for-pce-controller] specify an object 317 called CCI for the encoding of the central controller's instructions 318 for Label. This document extends the CCI by defining a new object- 319 type for SR-MPLS. The PCEP messages are extended in this document to 320 handle the PCECC operations for SR. 322 5.3. PCECC Capability Advertisement 324 During PCEP Initialization Phase, PCEP Speakers (PCE or PCC) 325 advertise their support of PCECC extensions. A PCEP Speaker includes 326 the "PCECC Capability" sub-TLV, described in 327 [I-D.ietf-pce-pcep-extension-for-pce-controller]. 329 A new S-bit is added in the PCECC-CAPABILITY sub-TLV to indicate 330 support for PCECC-SR for MPLS dataplane. A PCC MUST set the S-bit in 331 the PCECC-CAPABILITY sub-TLV and include the SR-PCE-CAPABILITY sub- 332 TLV ([RFC8664]) in the OPEN Object (inside the PATH-SETUP-TYPE- 333 CAPABILITY TLV) to support the PCECC SR-MPLS extensions defined in 334 this document. If the S-bit is set in the PCECC-CAPABILITY sub-TLV 335 and the SR-PCE-CAPABILITY sub-TLV is not advertised in the OPEN 336 Object, PCE SHOULD send a PCErr message with Error-Type=19 (Invalid 337 Operation) and Error-value=TBD4 (SR capability was not advertised) 338 and terminate the session. 340 The rest of the processing is as per 341 [I-D.ietf-pce-pcep-extension-for-pce-controller]. 343 5.4. PCEP session IP address and TED Router ID 345 A PCE may construct its Traffic Engineering Database (TED) by 346 participating in the IGP ([RFC3630] and [RFC5305] for MPLS-TE; 347 [RFC4203] and [RFC5307] for GMPLS). An alternative is offered by 348 BGP-LS [RFC7752] or [I-D.dhodylee-pce-pcep-ls]. 350 A PCEP [RFC5440] speaker could use any local IP address while 351 creating a TCP session. It is important to link the session IP 352 address with the Router ID in TED for successful PCECC operations. 354 During PCEP Initialization Phase, the PCC SHOULD advertise the TE 355 mapping information by including the "Node Attributes TLV" 356 [I-D.dhodylee-pce-pcep-ls] with "IPv4/IPv6 Router-ID of Local Node", 357 in the OPEN Object for this purpose. [RFC7752] describes the usage 358 as auxiliary Router-IDs that the IGP might be using, e.g., for TE 359 purposes. If there are more than one auxiliary Router-ID of a given 360 type, then multiple TLVs are used to encode them. 362 If "IPv4/IPv6 Router-ID" TLV is not present, the TCP session IP 363 address is directly used for mapping purpose. 365 [Editor's Note: "Node Attributes TLV" could be moved to this document 366 if the progresses of [I-D.dhodylee-pce-pcep-ls] is lagging. This 367 needs to be handled before the WG LC.] 369 5.5. LSP Operations 371 [RFC8664] specify the PCEP extension to allow a stateful PCE to 372 compute and initiate SR-TE paths, as well as a PCC to request a path 373 subject to certain constraint(s) and optimization criteria in SR 374 networks. 376 The Path Setup Type for segment routing (PST=1) is used on the PCEP 377 session with the Ingress as per [RFC8664]. 379 5.5.1. PCECC Segment Routing (SR) 381 Segment Routing (SR) as described in [RFC8402] depends on "segments" 382 that are advertised by Interior Gateway Protocols (IGPs). The SR- 383 node allocates and advertises the SID (node, adj, etc) and flood them 384 via the IGP. This document proposes a new mechanism where PCE 385 allocates the SID (label/index/SID) centrally and uses PCEP to 386 distribute them to all nodes. In some deployments, PCE (and PCEP) 387 are better suited than IGP because of the centralized nature of PCE 388 and direct TCP based PCEP sessions to all the nodes. Note that only 389 the SID allocation and distribution is done by the PCEP, all other SR 390 operations (nexthop selection, protection, etc) are still done by the 391 node (and the IGPs). 393 5.5.1.1. PCECC SR Node/Prefix SID allocation 395 Each node (PCC) is allocated a node-SID by the PCECC. The PCECC 396 sends PCInitiate message to update the label map of each node to all 397 the nodes in the domain. The TE router ID is determined from the TED 398 or from "IPv4/IPv6 Router-ID" Sub-TLV [I-D.dhodylee-pce-pcep-ls], in 399 the OPEN Object Section 5.4. 401 It is RECOMMENDED that PCEP session with PCECC-SR capability to use a 402 different session IP address during TCP session establishment than 403 the node Router ID in TEDB, to make sure that the PCEP session does 404 not get impacted by the SR Node/Prefix Label maps (Section 5.4). 406 If a node (PCC) receives a PCInitiate message with a CCI object- 407 type=TBD6 encoding a SID, out of the range set aside for the SR 408 Global Block (SRGB), it MUST send a PCErr message with Error-type=TBD 409 (PCECC failure) and Error-value=TBD (Label out of range) (defined in 410 [I-D.ietf-pce-pcep-extension-for-pce-controller]) and MUST include 411 the SRP object to specify the error is for the corresponding central 412 control instruction via the PCInitiate message. 414 On receiving the label map, each node (PCC) uses the local routing 415 information via IGP to determine the next-hop and download the label 416 forwarding instructions accordingly as shown in Figure 1. The 417 PCInitiate message in this case does not use the LSP object but uses 418 a new FEC object defined in Section 7.4. 420 +---------+ +-------+ 421 |PCC | | PCE | 422 |192.0.2.3| +-------+ 423 +------| | | 424 | PCC +---------+ | 425 | 192.0.2.2| | | 426 +------| | | | 427 |PCC +----------+ | | 428 |192.0.2.1| | | | 429 +---------+ | | | 430 | | | | 431 |<--------PCInitiate,FEC=192.0.2.1------------------| Label Map 432 | | | CC-ID=X | update 433 |--------PCRpt,CC-ID=X----------------------------->| CCI 434 |Find | | | 435 |Nexthop|<--------PCInitiate,FEC=192.0.2.1----------| Label Map 436 |locally| | CC-ID=Y | update 437 | |-------PCRpt,CC-ID=Y---------------------->| CCI 438 | | | | 439 | | |<----PCInitiate,FEC=192.0.2.1------| Label Map 440 | | | CC-ID=Z | update 441 | | |-----PCRpt,CC-ID=Z---------------->| CCI 442 | | | | 444 The forwarding behavior and the end result is similar to IGP based 445 "Node-SID" in SR. Thus, from anywhere in the domain, it enforces the 446 ECMP-aware shortest-path forwarding of the packet towards the related 447 node as per [RFC8402]. 449 PCE relies on the Node/Prefix Label clean up using the same 450 PCInitiate message as per [RFC8281]. 452 The above example Figure 1 depicts the FEC and PCEP speakers that 453 uses IPv4 address. Similarly an IPv6 address (such as 2001:db8::1) 454 can be used during PCEP session establishment in the FEC object as 455 described in this specification. 457 In the case where the label/SID allocation is made by the PCC itself 458 (see Section 5.5.1.6), the PCE could request an allocation to be made 459 by the PCC, and where the PCC would send a PCRpt with the allocated 460 label/SID encoded in the CC-ID object as shown in Figure 2. 462 +---------+ +-------+ 463 |PCC | | PCE | 464 |192.0.2.3| +-------+ 465 +------| | | 466 | PCC +---------+ | 467 | 192.0.2.2| | | 468 +------| | | | 469 |PCC +----------+ | | 470 |192.0.2.1| | | | 471 +---------+ | | | 472 | | | | 473 |<--------PCInitiate,FEC=192.0.2.1------------------| Label Map 474 | | | CC-ID=X,C=1 | request 475 |--------PCRpt,CC-ID=X,Label----------------------->| CCI 476 |Find | | | 477 |Nexthop|<--------PCInitiate,FEC=192.0.2.1----------| Label Map 478 |locally| | CC-ID=Y,C=0,Label | update 479 | |-------PCRpt,CC-ID=Y---------------------->| CCI 480 | | | | 481 | | |<----PCInitiate,FEC=192.0.2.1------| Label Map 482 | | | CC-ID=Z,C=0,Label | update 483 | | |-----PCRpt,CC-ID=Z---------------->| CCI 484 | | | | 486 It should be noted that in this example (Figure 2), the request is 487 made to the node 192.0.2.1 with C bit set in the CCI object to 488 indicate that the allocation needs to be done by this PCC and it 489 responds with the allocated label/SID to the PCE. The PCE would 490 further inform the other nodes (PCCs) in the network about the label- 491 map allocation without setting the C bit as before. 493 All other distributed operations such as nexthop change, protection, 494 etc is handled by the local node as before. 496 5.5.1.2. PCECC SR Adjacency Label allocation 498 For PCECC-SR, apart from node-SID, Adj-SID is used where each 499 adjacency is allocated an Adj-SID by the PCECC. The PCECC sends the 500 PCInitiate message to update the label map of each adjacency to all 501 the nodes in the domain as shown in Figure 3. Each node (PCC) 502 download the label forwarding instructions accordingly. Similar to 503 SR Node/Prefix Label allocation, the PCInitiate message in this case 504 does not use the LSP object but uses the new FEC object defined in 505 this document. 507 +---------+ +-------+ 508 |PCC | | PCE | 509 |192.0.2.3| +-------+ 510 +------| | | 511 | PCC +---------+ | 512 | 192.0.2.2| | | 513 +------| | | | 514 |PCC +----------+ | | 515 |192.0.2.1| | | | 516 +---------+ | | | 517 | | | | 518 |<-------PCInitiate,FEC=198.51.100.1--------------| Label Map 519 | | | 198.51.100.2 | update 520 | | | CC-ID=A | CCI 521 |--------PCRpt,CC-ID=A--------------------------->| 522 | | | | 523 | |<------PCInitiate,FEC=198.51.100.1------| Label Map 524 | | | 198.51.100.2 | update 525 | | | CC-ID=B | CCI 526 | |-------PCRpt,CC-ID=B------------------->| 527 | | | | 528 | | | | 529 | | |<---PCInitiate,FEC=198.51.100.1--| Label Map 530 | | | 198.51.100.2 | update 531 | | | CC-ID=C | CCI 532 | | |-------PCRpt,CC-ID=C------------>| 534 The forwarding behavior and the end result is similar to IGP based 535 "Adj-SID" in SR. The Adj-SID is distributed to all nodes to enable 536 SR-TE and TI-LFA. 538 PCE relies on the Adj SID/label clean up using the same PCInitiate 539 message as per [RFC8281]. 541 The above example (Figure 3) depicts FEC object and PCEP speakers 542 that uses an IPv4 address. Similarly an IPv6 address (such as 543 2001:db8::1, 2001:db8::2) can be used during the PCEP session 544 establishment in the FEC object as described in this specification. 546 The handling of adjacencies on the LAN subnetworks is specified in 547 [RFC8402]. PCECC MUST assign Adj-SID for every pair of routers in 548 the LAN. The rest of the protocol mechanism remains the same. 550 In the case where the label/SID map allocation is made by the PCC 551 itself (see Section 5.5.1.6), the PCE could request an allocation to 552 be made by the PCC, and where the PCC would send a PCRpt with the 553 allocated label/SID encoded in the CC-ID object as shown in Figure 4. 555 +---------+ +-------+ 556 |PCC | | PCE | 557 |192.0.2.3| +-------+ 558 +------| | | 559 | PCC +---------+ | 560 | 192.0.2.2| | | 561 +------| | | | 562 |PCC +----------+ | | 563 |192.0.2.1| | | | 564 +---------+ | | | 565 | | | | 566 |<-------PCInitiate,FEC=198.51.100.1--------------| Label Map 567 | | | 198.51.100.2 | request 568 | | | CC-ID=A,C=1 | CCI 569 |--------PCRpt,CC-ID=A,Label--------------------->| 570 | | | | 571 | |<------PCInitiate,FEC=198.51.100.1------| Label Map 572 | | | 198.51.100.2 | request 573 | | | CC-ID=B | CCI 574 | |-------PCRpt,CC-ID=B------------------->| 575 | | | | 576 | | |<---PCInitiate,FEC=198.51.100.1--| Label Map 577 | | | 198.51.100.2 | update 578 | | | CC-ID=C | CCI 579 | | |-------PCRpt,CC-ID=C------------>| 581 In this example (Figure 4), the request is made to the node 192.0.2.1 582 with the C bit set in the CCI object to indicate that the allocation 583 needs to be done by this PCC for the adjacency (198.51.100.1 - 584 198.51.100.2) and it responds with the allocated label/SID to the 585 PCE. The PCE further distribute this to other nodes without setting 586 the C bit as before. 588 5.5.1.3. Redundant PCEs 590 [I-D.litkowski-pce-state-sync] describes the synchronization 591 mechanism between the stateful PCEs. The SR SIDs allocated by a PCE 592 MUST also be synchronized among PCEs for PCECC SR state 593 synchronization. Note that the SR SIDs are independent of the SR-TE 594 LSPs, and remains intact till any topology change. The redundant 595 PCEs MUST have a common view of all SR SIDs allocated in the domain. 597 5.5.1.4. Re Delegation and Clean up 599 [I-D.ietf-pce-pcep-extension-for-pce-controller] describes the action 600 needed for CCIs for the static LSPs on a terminated session. Same 601 holds true for the CCI Object-Type=TBD6 for SR SID as well. 603 5.5.1.5. Synchronization of Label Allocations 605 [I-D.ietf-pce-pcep-extension-for-pce-controller] describes the 606 synchronization of Central Controller's Instructions (CCI) via LSP 607 state synchronization as described in [RFC8231] and [RFC8232]. Same 608 procedures are applied for the CCI for SR SID as well. 610 5.5.1.6. PCC-Based Allocations 612 The PCE can request the PCC to allocate the label/SID using the 613 PCInitiate message. The C flag in the CCI object is set to 1 to 614 indicate that the allocation needs to be done by the PCC. The PCC 615 would allocate the SID/Label/Index and would report to the PCE using 616 the PCRpt message. 618 If the value of the SID/Label/Index is 0 and the C flag is set to 1, 619 it indicates that the PCE is requesting the allocation to be done by 620 the PCC. If the SID/Label/Index is 'n' and the C flag is set to 1 in 621 the CCI object, it indicates that the PCE requests a specific value 622 'n' for the SID/Label/Index. If the allocation is successful, the 623 PCC should report via PCRpt message with the CCI object. Else, it 624 MUST send a PCErr message with Error-Type = TBD ("PCECC failure") and 625 Error Value = TBD ("Invalid CCI") (defined in 626 [I-D.ietf-pce-pcep-extension-for-pce-controller]). If the value of 627 the SID/Label/Index in the CCI object is valid, but the PCC is unable 628 to allocate it, it MUST send a PCErr message with Error-Type = TBD 629 ("PCECC failure") and Error Value = TBD ("Unable to allocate the 630 specified CCI") (defined in 631 [I-D.ietf-pce-pcep-extension-for-pce-controller]). 633 If the PCC wishes to withdraw or modify the previously assigned 634 label/SID, it MUST send a PCRpt message without any SID/Label/Index 635 or with the SID/Label/Index containing the new value respectively in 636 the CCI object. The PCE would further trigger the removal of the 637 central controller instruction as per this document. 639 5.5.1.7. Binding SID 641 A PCECC can allocate and provision the node/prefix/adjacency label 642 (SID) via PCEP. Another SID called binding SID is described in 643 [I-D.ietf-pce-binding-label-sid], the PCECC mechanism can also be 644 used to allocate the binding SID. 646 A procedure for binding label/SID allocation is described in 647 [I-D.ietf-pce-pcep-extension-for-pce-controller] and is applicable 648 for all path setup types (including SR paths). 650 6. PCEP Messages 652 As defined in [RFC5440], a PCEP message consists of a common header 653 followed by a variable-length body made of a set of objects that can 654 be either mandatory or optional. An object is said to be mandatory 655 in a PCEP message when the object must be included for the message to 656 be considered valid. For each PCEP message type, a set of rules is 657 defined that specify the set of objects that the message can carry. 658 An implementation MUST form the PCEP messages using the object 659 ordering specified in this document. 661 Message formats in this section are presented using Routing Backus- 662 Naur Format (RBNF) as specified in [RFC5511]. 664 6.1. Central Control Instructions 666 6.1.1. The PCInitiate Message 668 The PCInitiate message defined in [RFC8281] and extended in 669 [I-D.ietf-pce-pcep-extension-for-pce-controller] is further extended 670 to support SR based central control instructions. 672 The format of the extended PCInitiate message is as follows: 674 ::= 675 676 Where: 677 is defined in [RFC5440] 679 ::= 680 [] 682 ::= 683 (| 684 | 685 ) 687 ::= 688 ( 689 )| 690 ( 691 ) 693 ::= 694 [] 696 Where: 697 and 698 are as per 699 [RFC8281]. 701 The LSP and SRP object is defined in [RFC8231]. 703 When the PCInitiate message is used to distribute SR SIDs, the SRP, 704 the FEC and the CCI object of object-type=TBD6 MUST be present. The 705 error handling for missing SRP or CCI object is as per 706 [I-D.ietf-pce-pcep-extension-for-pce-controller]. If the FEC object 707 is missing, the receiving PCC MUST send a PCErr message with Error- 708 type=6 (Mandatory Object missing) and Error-value=TBD5 (FEC object 709 missing). 711 To clean up, the R (remove) bit in the SRP object and the 712 corresponding FEC and the CCI object are included. 714 6.1.2. The PCRpt message 716 The PCRpt message can be used to report the SR central controller 717 instructions received from the PCECC during the state synchronization 718 phase or as an acknowledgment to the PCInitiate message. 720 The format of the PCRpt message is as follows: 722 ::= 723 724 Where: 726 ::= [] 728 ::= (| 729 ) 731 ::= [] 732 733 735 ::= [] 736 ( 737 )| 738 ( 739 ) 741 ::= 742 [] 744 Where: 745 is as per [RFC8231] and the LSP and SRP object are 746 also defined in [RFC8231]. 748 When PCRpt message is used to report the label map allocations, the 749 FEC and CCI object of object-type=TBD6 MUST be present. The error 750 handling for the missing CCI object is as per 751 [I-D.ietf-pce-pcep-extension-for-pce-controller]. If the FEC object 752 is missing, the receiving PCE MUST send a PCErr message with Error- 753 type=6 (Mandatory Object missing) and Error-value=TBD5 (FEC object 754 missing). 756 7. PCEP Objects 758 7.1. OPEN Object 760 7.1.1. PCECC Capability sub-TLV 762 [I-D.ietf-pce-pcep-extension-for-pce-controller] defined the PCECC- 763 CAPABILITY sub-TLV. 765 A new S-bit is added in PCECC-CAPABILITY sub-TLV for PCECC-SR: 767 0 1 2 3 768 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 1 769 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 770 | Type=TBD | Length=4 | 771 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 772 | Flags |S|L| 773 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 775 [Editor's Note - The above figure is included for ease of the reader 776 but should be removed before publication.] 778 S (PCECC-SR-CAPABILITY - 1 bit - TBD1): If set to 1 by a PCEP 779 speaker, it indicates that the PCEP speaker is capable of PCECC-SR 780 capability and the PCE allocates the Node and Adj label/SID on this 781 session. 783 7.2. SR-TE Path Setup 785 The PATH-SETUP-TYPE TLV is defined in [RFC8408]. A PST value of 1 is 786 used when Path is setup via SR mode as per [RFC8664]. The procedure 787 for SR-TE path setup as specified in [RFC8664] remains unchanged. 789 7.3. CCI Object 791 The Central Control Instructions (CCI) Object used by the PCE to 792 specify the controller instructions is defined in 793 [I-D.ietf-pce-pcep-extension-for-pce-controller]. This document 794 defines another object-type for SR-MPLS purpose. 796 CCI Object-Type is TBD6 for SR-MPLS as below - 798 0 1 2 3 799 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 1 800 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 801 | CC-ID | 802 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 803 | MT-ID | Algorithm | Flags |B|P|G|C|N|E|V|L| 804 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 805 // SID/Label/Index (variable) // 806 +---------------------------------------------------------------+ 807 | | 808 // Optional TLV // 809 | | 810 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 811 The field CC-ID is as described in 812 [I-D.ietf-pce-pcep-extension-for-pce-controller]. Following new 813 fields are defined for CCI Object-Type TBD6 - 815 MT-ID: Multi-Topology ID (as defined in [RFC4915]). 817 Algorithm: Single octet identifying the algorithm the SID is 818 associated with. See [RFC8665]. 820 Flags: is used to carry any additional information pertaining to the 821 CCI. The following bits are defined - 823 * L-Bit (Local/Global): If set, then the value/index carried by 824 the CCI object has local significance. If not set, then the 825 value/index carried by this object has global significance. 827 * V-Bit (Value/Index): If set, then the CCI carries an absolute 828 value. If not set, then the CCI carries an index. 830 * E-Bit (Explicit-Null): If set, any upstream neighbor of the 831 node that advertised the SID MUST replace the SID with the 832 Explicit-NULL label (0 for IPv4) before forwarding the packet. 834 * N-Bit (No-PHP): If set, then the penultimate hop MUST NOT pop 835 the SID before delivering packets to the node that advertised 836 the SID. 838 * C-Bit (PCC Allocation): If the bit is set to 1, it indicates 839 that the SR SID/label allocation needs to be done by the PCC 840 for this central controller instruction. A PCE set this bit to 841 request the PCC to make an allocation from its SR label/ID 842 space. A PCC would set this bit to indicate that it has 843 allocated the SR SID/label and report it to the PCE. 845 * Following bits are applicable when the SID represents an Adj- 846 SID only, it MUST be ignored for others - 848 + G-Bit (Group): When set, the G-Flag indicates that the Adj- 849 SID refers to a group of adjacencies (and therefore MAY be 850 assigned to other adjacencies as well). 852 + P-Bit (Persistent): When set, the P-Flag indicates that the 853 Adj-SID is persistently allocated, i.e., the Adj-SID value 854 remains consistent across router restart and/or interface 855 flap. 857 + B-Bit (Backup): If set, the Adj-SID refers to an adjacency 858 that is eligible for protection (e.g., using IP Fast Reroute 859 or MPLS-FRR (MPLS-Fast Reroute) as described in Section 2.1 860 of [RFC8402]. 862 + All unassigned bits MUST be set to zero at transmission and 863 ignored at receipt. 865 SID/Label/Index: According to the V and L flags, it contains either: 867 A 32-bit index defining the offset in the SID/Label space 868 advertised by this router. 870 A 24-bit label where the 20 rightmost bits are used for 871 encoding the label value. 873 7.4. FEC Object 875 The FEC Object is used to specify the FEC information and MAY be 876 carried within PCInitiate or PCRpt message. 878 FEC Object-Class is TBD3. 880 FEC Object-Type is 1 'IPv4 Node ID'. 882 0 1 2 3 883 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 1 884 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 885 | IPv4 Node ID | 886 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 888 FEC Object-Type is 2 'IPv6 Node ID'. 890 0 1 2 3 891 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 1 892 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 893 | | 894 // IPv6 Node ID (16 bytes) // 895 | | 896 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 898 FEC Object-Type is 3 'IPv4 Adjacency'. 900 0 1 2 3 901 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 1 902 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 903 | Local IPv4 address | 904 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 905 | Remote IPv4 address | 906 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 908 FEC Object-Type is 4 'IPv6 Adjacency'. 910 0 1 2 3 911 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 1 912 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 913 | | 914 // Local IPv6 address (16 bytes) // 915 | | 916 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 917 | | 918 // Remote IPv6 address (16 bytes) // 919 | | 920 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 922 FEC Object-Type is 5 'Unnumbered Adjacency with IPv4 NodeIDs'. 924 0 1 2 3 925 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 1 926 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 927 | Local Node-ID | 928 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 929 | Local Interface ID | 930 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 931 | Remote Node-ID | 932 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 933 | Remote Interface ID | 934 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 936 FEC Object-Type is 6 'Linklocal IPv6 Adjacency'. 938 0 1 2 3 939 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 1 940 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 941 // Local IPv6 address (16 octets) // 942 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 943 | Local Interface ID | 944 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 945 // Remote IPv6 address (16 octets) // 946 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 947 | Remote Interface ID | 948 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 950 The FEC objects are as follows: 952 IPv4 Node ID: where IPv4 Node ID is specified as an IPv4 address of 953 the Node. FEC Object-type is 1, and the Object-Length is 4 in this 954 case. 956 IPv6 Node ID: where IPv6 Node ID is specified as an IPv6 address of 957 the Node. FEC Object-type is 2, and the Object-Length is 16 in this 958 case. 960 IPv4 Adjacency: where Local and Remote IPv4 address is specified as 961 pair of IPv4 addresses of the adjacency. FEC Object-type is 3, and 962 the Object-Length is 8 in this case. 964 IPv6 Adjacency: where Local and Remote IPv6 address is specified as 965 pair of IPv6 addresses of the adjacency. FEC Object-type is 4, and 966 the Object-Length is 32 in this case. 968 Unnumbered Adjacency with IPv4 NodeID: where a pair of Node ID / 969 Interface ID tuple is used. FEC Object-type is 5, and the Object- 970 Length is 16 in this case. 972 Linklocal IPv6 Adjacency: where a pair of (global IPv6 address, 973 interface ID) tuple is used. FEC object-type is 6, and the Object- 974 Length is 40 in this case. 976 8. Implementation Status 978 [Note to the RFC Editor - remove this section before publication, as 979 well as remove the reference to RFC 7942.] 981 This section records the status of known implementations of the 982 protocol defined by this specification at the time of posting of this 983 Internet-Draft, and is based on a proposal described in [RFC7942]. 984 The description of implementations in this section is intended to 985 assist the IETF in its decision processes in progressing drafts to 986 RFCs. Please note that the listing of any individual implementation 987 here does not imply endorsement by the IETF. Furthermore, no effort 988 has been spent to verify the information presented here that was 989 supplied by IETF contributors. This is not intended as, and must not 990 be construed to be, a catalog of available implementations or their 991 features. Readers are advised to note that other implementations may 992 exist. 994 According to [RFC7942], "this will allow reviewers and working groups 995 to assign due consideration to documents that have the benefit of 996 running code, which may serve as evidence of valuable experimentation 997 and feedback that have made the implemented protocols more mature. 999 It is up to the individual working groups to use this information as 1000 they see fit". 1002 8.1. Huawei's Proof of Concept based on ONOS 1004 The PCE function was developed in the ONOS open source platform. 1005 This extension was implemented on a private version as a proof of 1006 concept for PCECC. 1008 o Organization: Huawei 1010 o Implementation: Huawei's PoC based on ONOS 1012 o Description: PCEP as a southbound plugin was added to ONOS. To 1013 support PCECC-SR, an earlier version of this I-D was implemented. 1014 Refer https://wiki.onosproject.org/display/ONOS/PCEP+Protocol 1016 o Maturity Level: Prototype 1018 o Coverage: Partial 1020 o Contact: satishk@huawei.com 1022 9. Security Considerations 1024 As per [RFC8283], the security considerations for a PCE-based 1025 controller is a little different from those for any other PCE system. 1026 That is, the operation relies heavily on the use and security of 1027 PCEP, so consideration should be given to the security features 1028 discussed in [RFC5440] and the additional mechanisms described in 1029 [RFC8253]. It further lists the vulnerability of a central 1030 controller architecture, such as a central point of failure, denial- 1031 of-service, and a focus for interception and modification of messages 1032 sent to individual NEs. 1034 The PCECC extension builds on the existing PCEP messages and thus the 1035 security considerations described in [RFC5440], [RFC8231], [RFC8281], 1036 and [I-D.ietf-pce-pcep-extension-for-pce-controller] continue to 1037 apply. 1039 As per [RFC8231], it is RECOMMENDED that these PCEP extensions only 1040 be activated on mutually-authenticated and encrypted sessions across 1041 PCEs and PCCs belonging to the same administrative authority, using 1042 Transport Layer Security (TLS) [RFC8253] as per the recommendations 1043 and best current practices in [RFC7525] (unless explicitly set aside 1044 in [RFC8253]). 1046 10. Manageability Considerations 1048 10.1. Control of Function and Policy 1050 A PCE or PCC implementation SHOULD allow to configure to enable/ 1051 disable PCECC SR capability as a global configuration. The 1052 implementation SHOULD also allow setting the local IP address used by 1053 the PCEP session. 1055 10.2. Information and Data Models 1057 [RFC7420] describes the PCEP MIB, this MIB can be extended to get the 1058 PCECC SR capability status. 1060 The PCEP YANG module [I-D.ietf-pce-pcep-yang] could be extended to 1061 enable/disable PCECC SR capability. 1063 10.3. Liveness Detection and Monitoring 1065 Mechanisms defined in this document do not imply any new liveness 1066 detection and monitoring requirements in addition to those already 1067 listed in [RFC5440]. 1069 10.4. Verify Correct Operations 1071 Mechanisms defined in this document do not imply any new operation 1072 verification requirements in addition to those already listed in 1073 [RFC5440], [RFC8231], and 1074 [I-D.ietf-pce-pcep-extension-for-pce-controller]. 1076 10.5. Requirements On Other Protocols 1078 PCEP extensions defined in this document do not put new requirements 1079 on other protocols. 1081 10.6. Impact On Network Operations 1083 PCEP extensions defined in this document allow SR SID Label 1084 allocation to be done from a central controller and thus simplifying 1085 the initial network operations. 1087 11. IANA Considerations 1089 11.1. PCECC-CAPABILITY sub-TLV 1091 [I-D.ietf-pce-pcep-extension-for-pce-controller] defines the PCECC- 1092 CAPABILITY sub-TLV and requests that IANA to create a new sub- 1093 registry to manage the value of the PCECC-CAPABILITY sub-TLV's Flag 1094 field. 1096 IANA is requested to allocate a new bit in the PCECC-CAPABILITY sub- 1097 TLV Flag Field sub-registry, as follows: 1099 Bit Description Reference 1100 TBD1 SR-MPLS This document 1102 11.2. PCEP Object 1104 IANA is requested to allocate new code-points for the new FEC object 1105 and a new Object-Type for CCI object in "PCEP Objects" sub-registry 1106 as follows: 1108 Object- Name Object-Type Reference 1109 Class 1110 Value 1111 TBD3 FEC 1: IPv4 This document 1112 Node ID 1113 2: IPv6 This document 1114 Node ID 1115 3: IPv4 This document 1116 Adjacency 1117 4: IPv6 This document 1118 Adjacency 1119 5: This document 1120 Unnumbered 1121 Adjacency 1122 with IPv4 1123 NodeID 1124 6: This document 1125 Linklocal 1126 IPv6 1127 Adjacency 1128 TBD CCI [I-D.ietf-pce-pcep-extension-for-pce-cont 1129 roller] 1130 TBD6: SR- This document 1131 MPLS 1133 11.3. PCEP-Error Object 1135 IANA is requested to allocate a new error-value within the "PCEP- 1136 ERROR Object Error Types and Values" sub-registry of the PCEP Numbers 1137 registry for the following errors: 1139 Error-Type Meaning 1140 ---------- ------- 1141 6 Mandatory Object missing. 1143 Error-value = TBD5 : FEC object missing 1144 19 Invalid operation. 1146 Error-value = TBD4 : SR capability was 1147 not advertised 1149 The Reference is marked as "This document". 1151 11.4. CCI Object Flag Field for SR 1153 IANA is requested to create a new sub-registry to manage the Flag 1154 field of the CCI Object-Type=TBD6 for SR called "CCI Object Flag 1155 Field for SR". New values are to be assigned by Standards Action 1156 [RFC8126]. Each bit should be tracked with the following qualities: 1158 o Bit number (counting from bit 0 as the most significant bit) 1159 o Capability description 1160 o Defining RFC 1162 Following bits are defined for the CCI Object flag field for SR in 1163 this document as follows: 1165 Bit Description Reference 1166 0-7 Unassigned This document 1167 8 B-Bit - Backup This document 1168 9 P-Bit - Persistent This document 1169 10 G-Bit - Group This document 1170 11 C-Bit - PCC Allocation This document 1171 12 N-Bit - No-PHP This document 1172 13 E-Bit - Explicit-Null This document 1173 14 V-Bit - Value/Index This document 1174 15 L-Bit - Local/Global This document 1176 12. Acknowledgments 1178 We would like to thank Robert Tao, Changjing Yan, Tieying Huang, 1179 Avantika, and Aijun Wang for their useful comments and suggestions. 1181 Further thanks to Stephane Litkowski, Robert Sawaya, Zafar Ali, and 1182 Mike Koldychev for useful discussion and ideas to improve the 1183 document. 1185 13. References 1187 13.1. Normative References 1189 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1190 Requirement Levels", BCP 14, RFC 2119, 1191 DOI 10.17487/RFC2119, March 1997, 1192 . 1194 [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering 1195 (TE) Extensions to OSPF Version 2", RFC 3630, 1196 DOI 10.17487/RFC3630, September 2003, 1197 . 1199 [RFC4203] Kompella, K., Ed. and Y. Rekhter, Ed., "OSPF Extensions in 1200 Support of Generalized Multi-Protocol Label Switching 1201 (GMPLS)", RFC 4203, DOI 10.17487/RFC4203, October 2005, 1202 . 1204 [RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P. 1205 Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF", 1206 RFC 4915, DOI 10.17487/RFC4915, June 2007, 1207 . 1209 [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic 1210 Engineering", RFC 5305, DOI 10.17487/RFC5305, October 1211 2008, . 1213 [RFC5307] Kompella, K., Ed. and Y. Rekhter, Ed., "IS-IS Extensions 1214 in Support of Generalized Multi-Protocol Label Switching 1215 (GMPLS)", RFC 5307, DOI 10.17487/RFC5307, October 2008, 1216 . 1218 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 1219 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 1220 DOI 10.17487/RFC5440, March 2009, 1221 . 1223 [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and 1224 S. Ray, "North-Bound Distribution of Link-State and 1225 Traffic Engineering (TE) Information Using BGP", RFC 7752, 1226 DOI 10.17487/RFC7752, March 2016, 1227 . 1229 [RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running 1230 Code: The Implementation Status Section", BCP 205, 1231 RFC 7942, DOI 10.17487/RFC7942, July 2016, 1232 . 1234 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 1235 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 1236 May 2017, . 1238 [RFC8231] Crabbe, E., Minei, I., Medved, J., and R. Varga, "Path 1239 Computation Element Communication Protocol (PCEP) 1240 Extensions for Stateful PCE", RFC 8231, 1241 DOI 10.17487/RFC8231, September 2017, 1242 . 1244 [RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody, 1245 "PCEPS: Usage of TLS to Provide a Secure Transport for the 1246 Path Computation Element Communication Protocol (PCEP)", 1247 RFC 8253, DOI 10.17487/RFC8253, October 2017, 1248 . 1250 [RFC8281] Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "Path 1251 Computation Element Communication Protocol (PCEP) 1252 Extensions for PCE-Initiated LSP Setup in a Stateful PCE 1253 Model", RFC 8281, DOI 10.17487/RFC8281, December 2017, 1254 . 1256 [RFC8408] Sivabalan, S., Tantsura, J., Minei, I., Varga, R., and J. 1257 Hardwick, "Conveying Path Setup Type in PCE Communication 1258 Protocol (PCEP) Messages", RFC 8408, DOI 10.17487/RFC8408, 1259 July 2018, . 1261 [RFC8664] Sivabalan, S., Filsfils, C., Tantsura, J., Henderickx, W., 1262 and J. Hardwick, "Path Computation Element Communication 1263 Protocol (PCEP) Extensions for Segment Routing", RFC 8664, 1264 DOI 10.17487/RFC8664, December 2019, 1265 . 1267 [I-D.ietf-pce-pcep-extension-for-pce-controller] 1268 Li, Z., Peng, S., Negi, M., Zhao, Q., and C. Zhou, "PCEP 1269 Procedures and Protocol Extensions for Using PCE as a 1270 Central Controller (PCECC) of LSPs", draft-ietf-pce-pcep- 1271 extension-for-pce-controller-10 (work in progress), 1272 January 2021. 1274 [I-D.dhodylee-pce-pcep-ls] 1275 Dhody, D., Peng, S., Lee, Y., Ceccarelli, D., Wang, A., 1276 and G. Mishra, "PCEP extensions for Distribution of Link- 1277 State and TE Information", draft-dhodylee-pce-pcep-ls-19 1278 (work in progress), November 2020. 1280 13.2. Informative References 1282 [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol 1283 Label Switching Architecture", RFC 3031, 1284 DOI 10.17487/RFC3031, January 2001, 1285 . 1287 [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation 1288 Element (PCE)-Based Architecture", RFC 4655, 1289 DOI 10.17487/RFC4655, August 2006, 1290 . 1292 [RFC5511] Farrel, A., "Routing Backus-Naur Form (RBNF): A Syntax 1293 Used to Form Encoding Rules in Various Routing Protocol 1294 Specifications", RFC 5511, DOI 10.17487/RFC5511, April 1295 2009, . 1297 [RFC7025] Otani, T., Ogaki, K., Caviglia, D., Zhang, F., and C. 1298 Margaria, "Requirements for GMPLS Applications of PCE", 1299 RFC 7025, DOI 10.17487/RFC7025, September 2013, 1300 . 1302 [RFC7399] Farrel, A. and D. King, "Unanswered Questions in the Path 1303 Computation Element Architecture", RFC 7399, 1304 DOI 10.17487/RFC7399, October 2014, 1305 . 1307 [RFC7420] Koushik, A., Stephan, E., Zhao, Q., King, D., and J. 1308 Hardwick, "Path Computation Element Communication Protocol 1309 (PCEP) Management Information Base (MIB) Module", 1310 RFC 7420, DOI 10.17487/RFC7420, December 2014, 1311 . 1313 [RFC7491] King, D. and A. Farrel, "A PCE-Based Architecture for 1314 Application-Based Network Operations", RFC 7491, 1315 DOI 10.17487/RFC7491, March 2015, 1316 . 1318 [RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre, 1319 "Recommendations for Secure Use of Transport Layer 1320 Security (TLS) and Datagram Transport Layer Security 1321 (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May 1322 2015, . 1324 [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for 1325 Writing an IANA Considerations Section in RFCs", BCP 26, 1326 RFC 8126, DOI 10.17487/RFC8126, June 2017, 1327 . 1329 [RFC8232] Crabbe, E., Minei, I., Medved, J., Varga, R., Zhang, X., 1330 and D. Dhody, "Optimizations of Label Switched Path State 1331 Synchronization Procedures for a Stateful PCE", RFC 8232, 1332 DOI 10.17487/RFC8232, September 2017, 1333 . 1335 [RFC8283] Farrel, A., Ed., Zhao, Q., Ed., Li, Z., and C. Zhou, "An 1336 Architecture for Use of PCE and the PCE Communication 1337 Protocol (PCEP) in a Network with Central Control", 1338 RFC 8283, DOI 10.17487/RFC8283, December 2017, 1339 . 1341 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 1342 Decraene, B., Litkowski, S., and R. Shakir, "Segment 1343 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 1344 July 2018, . 1346 [RFC8660] Bashandy, A., Ed., Filsfils, C., Ed., Previdi, S., 1347 Decraene, B., Litkowski, S., and R. Shakir, "Segment 1348 Routing with the MPLS Data Plane", RFC 8660, 1349 DOI 10.17487/RFC8660, December 2019, 1350 . 1352 [RFC8665] Psenak, P., Ed., Previdi, S., Ed., Filsfils, C., Gredler, 1353 H., Shakir, R., Henderickx, W., and J. Tantsura, "OSPF 1354 Extensions for Segment Routing", RFC 8665, 1355 DOI 10.17487/RFC8665, December 2019, 1356 . 1358 [RFC8667] Previdi, S., Ed., Ginsberg, L., Ed., Filsfils, C., 1359 Bashandy, A., Gredler, H., and B. Decraene, "IS-IS 1360 Extensions for Segment Routing", RFC 8667, 1361 DOI 10.17487/RFC8667, December 2019, 1362 . 1364 [I-D.ietf-teas-pcecc-use-cases] 1365 Li, Z., Khasanov, B., Dhody, D., Zhao, Q., Ke, Z., Fang, 1366 L., Zhou, C., Communications, T., Rachitskiy, A., and A. 1367 Gulida, "The Use Cases for Path Computation Element (PCE) 1368 as a Central Controller (PCECC).", draft-ietf-teas-pcecc- 1369 use-cases-06 (work in progress), September 2020. 1371 [I-D.ietf-pce-pcep-yang] 1372 Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A 1373 YANG Data Model for Path Computation Element 1374 Communications Protocol (PCEP)", draft-ietf-pce-pcep- 1375 yang-15 (work in progress), October 2020. 1377 [I-D.ietf-pce-binding-label-sid] 1378 Sivabalan, S., Filsfils, C., Tantsura, J., Hardwick, J., 1379 Previdi, S., and C. Li, "Carrying Binding Label/Segment-ID 1380 in PCE-based Networks.", draft-ietf-pce-binding-label- 1381 sid-05 (work in progress), October 2020. 1383 [I-D.litkowski-pce-state-sync] 1384 Litkowski, S., Sivabalan, S., Li, C., and H. Zheng, "Inter 1385 Stateful Path Computation Element (PCE) Communication 1386 Procedures.", draft-litkowski-pce-state-sync-09 (work in 1387 progress), November 2020. 1389 [I-D.dhody-pce-pcep-extension-pce-controller-srv6] 1390 Li, Z., Peng, S., Geng, X., and M. Negi, "PCEP Procedures 1391 and Protocol Extensions for Using PCE as a Central 1392 Controller (PCECC) for SRv6", draft-dhody-pce-pcep- 1393 extension-pce-controller-srv6-05 (work in progress), 1394 November 2020. 1396 [I-D.li-pce-controlled-id-space] 1397 Li, C., Chen, M., Wang, A., Cheng, W., and C. Zhou, "PCE 1398 Controlled ID Space", draft-li-pce-controlled-id-space-07 1399 (work in progress), October 2020. 1401 Appendix A. Contributor Addresses 1403 Dhruv Dhody 1404 Huawei Technologies 1405 Divyashree Techno Park, Whitefield 1406 Bangalore, Karnataka 560066 1407 India 1409 EMail: dhruv.ietf@gmail.com 1411 Satish Karunanithi 1412 Huawei Technologies 1413 Divyashree Techno Park, Whitefield 1414 Bangalore, Karnataka 560066 1415 India 1417 EMail: satishk@huawei.com 1419 Adrian Farrel 1420 Old Dog Consulting 1421 UK 1423 EMail: adrian@olddog.co.uk 1425 Xuesong Geng 1426 Huawei Technologies 1427 China 1429 Email: gengxuesong@huawei.com 1431 Udayasree Palle 1433 EMail: udayasreereddy@gmail.com 1435 Katherine Zhao 1436 Huawei Technologies 1437 2330 Central Expressway 1438 Santa Clara, CA 95050 1439 USA 1441 EMail: katherine.zhao@huawei.com 1443 Boris Zhang 1444 Telus Ltd. 1445 Toronto 1446 Canada 1448 EMail: boris.zhang@telus.com 1449 Alex Tokar 1450 Cisco Systems 1451 Slovak Republic 1453 EMail: atokar@cisco.com 1455 Authors' Addresses 1457 Zhenbin Li 1458 Huawei Technologies 1459 Huawei Bld., No.156 Beiqing Rd. 1460 Beijing 100095 1461 China 1463 EMail: lizhenbin@huawei.com 1465 Shuping Peng 1466 Huawei Technologies 1467 Huawei Bld., No.156 Beiqing Rd. 1468 Beijing 100095 1469 China 1471 EMail: pengshuping@huawei.com 1473 Mahendra Singh Negi 1474 RtBrick Inc 1475 N-17L, 18th Cross Rd, HSR Layout 1476 Bangalore, Karnataka 560102 1477 India 1479 EMail: mahend.ietf@gmail.com 1481 Quintin Zhao 1482 Etheric Networks 1483 1009 S CLAREMONT ST 1484 SAN MATEO, CA 94402 1485 USA 1487 EMail: qzhao@ethericnetworks.com 1488 Chao Zhou 1489 HPE 1491 EMail: chaozhou_us@yahoo.com