idnits 2.17.1 draft-ietf-pce-segment-routing-07.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 == Line 415 has weird spacing: '...L' Flag indic...' == Line 421 has weird spacing: '... Type is th...' == Line 424 has weird spacing: '... Length conta...' == Line 437 has weird spacing: '... Flags is us...' == Using lowercase 'not' together with uppercase 'MUST', 'SHALL', 'SHOULD', or 'RECOMMENDED' is not an accepted usage according to RFC 2119. Please use uppercase 'NOT' together with RFC 2119 keywords (if that is what you mean). Found 'MUST not' in this paragraph: As defined in [RFC5440], a PCEP message consists of a common header followed by a variable length body made up of mandatory and/or optional objects. This document does not require any changes in the format of PCReq and PCRep messages specified in [RFC5440], PCInitiate message specified in [I-D.ietf-pce-pce-initiated-lsp], and PCRpt and PCUpd messages specified in [I-D.ietf-pce-stateful-pce]. However, PCEP messages pertaining to SR-TE LSP MUST include PATH-SETUP-TYPE TLV in the RP or SRP object to clearly identify that SR-TE LSP is intended. In other words, a PCEP speaker MUST not infer whether or not a PCEP message pertains to SR-TE LSP from any other object or TLV. == Using lowercase 'not' together with uppercase 'MUST', 'SHALL', 'SHOULD', or 'RECOMMENDED' is not an accepted usage according to RFC 2119. Please use uppercase 'NOT' together with RFC 2119 keywords (if that is what you mean). Found 'MUST not' in this paragraph: The 'L' Flag indicates whether the subobject represents a loose-hop in the LSP [RFC3209]. If this flag is unset, a PCC MUST not overwrite the SID value present in the SR-ERO subobject. Otherwise, a PCC MAY expand or replace one or more SID value(s) in the received SR-ERO based on its local policy. -- The document date (March 21, 2016) is 2952 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) == Outdated reference: A later version (-25) exists of draft-ietf-isis-segment-routing-extensions-00 == Outdated reference: A later version (-27) exists of draft-ietf-ospf-segment-routing-extensions-00 == Outdated reference: A later version (-10) exists of draft-ietf-pce-lsp-setup-type-00 == Outdated reference: A later version (-11) exists of draft-ietf-pce-pce-initiated-lsp-01 == Outdated reference: A later version (-11) exists of draft-ietf-pce-pcep-mib-04 == Outdated reference: A later version (-21) exists of draft-ietf-pce-stateful-pce-05 Summary: 0 errors (**), 0 flaws (~~), 13 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group S. Sivabalan 3 Internet-Draft J. Medved 4 Intended status: Standards Track C. Filsfils 5 Expires: September 22, 2016 Cisco Systems, Inc. 6 E. Crabbe 8 R. Raszuk 9 Mirantis Inc. 10 V. Lopez 11 Telefonica I+D 12 J. Tantsura 13 Ericsson 14 W. Henderickx 15 Alcatel Lucent 16 J. Hardwick 17 Metaswitch Networks 18 March 21, 2016 20 PCEP Extensions for Segment Routing 21 draft-ietf-pce-segment-routing-07.txt 23 Abstract 25 Segment Routing (SR) enables any head-end node to select any path 26 without relying on a hop-by-hop signaling technique (e.g., LDP or 27 RSVP-TE). It depends only on "segments" that are advertised by Link- 28 State Interior Gateway Protocols (IGPs). A Segment Routed Path can 29 be derived from a variety of mechanisms, including an IGP Shortest 30 Path Tree (SPT), explicit configuration, or a Path Computation 31 Element (PCE). This document specifies extensions to the Path 32 Computation Element Protocol (PCEP) that allow a stateful PCE to 33 compute and initiate Traffic Engineering (TE) paths, as well as a PCC 34 to request a path subject to certain constraint(s) and optimization 35 criteria in SR networks. 37 Requirements Language 39 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 40 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 41 document are to be interpreted as described in [RFC2119]. 43 Status of This Memo 45 This Internet-Draft is submitted in full conformance with the 46 provisions of BCP 78 and BCP 79. 48 Internet-Drafts are working documents of the Internet Engineering 49 Task Force (IETF). Note that other groups may also distribute 50 working documents as Internet-Drafts. The list of current Internet- 51 Drafts is at http://datatracker.ietf.org/drafts/current/. 53 Internet-Drafts are draft documents valid for a maximum of six months 54 and may be updated, replaced, or obsoleted by other documents at any 55 time. It is inappropriate to use Internet-Drafts as reference 56 material or to cite them other than as "work in progress." 58 This Internet-Draft will expire on September 22, 2016. 60 Copyright Notice 62 Copyright (c) 2016 IETF Trust and the persons identified as the 63 document authors. All rights reserved. 65 This document is subject to BCP 78 and the IETF Trust's Legal 66 Provisions Relating to IETF Documents 67 (http://trustee.ietf.org/license-info) in effect on the date of 68 publication of this document. Please review these documents 69 carefully, as they describe your rights and restrictions with respect 70 to this document. Code Components extracted from this document must 71 include Simplified BSD License text as described in Section 4.e of 72 the Trust Legal Provisions and are provided without warranty as 73 described in the Simplified BSD License. 75 Table of Contents 77 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 78 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 79 3. Overview of PCEP Operation in SR Networks . . . . . . . . . . 5 80 4. SR-Specific PCEP Message Extensions . . . . . . . . . . . . . 7 81 5. Object Formats . . . . . . . . . . . . . . . . . . . . . . . 7 82 5.1. The OPEN Object . . . . . . . . . . . . . . . . . . . . . 7 83 5.1.1. The SR PCE Capability TLV . . . . . . . . . . . . . . 7 84 5.2. The RP/SRP Object . . . . . . . . . . . . . . . . . . . . 8 85 5.3. ERO Object . . . . . . . . . . . . . . . . . . . . . . . 8 86 5.3.1. SR-ERO Subobject . . . . . . . . . . . . . . . . . . 9 87 5.3.2. NAI Associated with SID . . . . . . . . . . . . . . . 11 88 5.3.3. ERO Processing . . . . . . . . . . . . . . . . . . . 12 89 5.4. RRO Object . . . . . . . . . . . . . . . . . . . . . . . 13 90 5.4.1. RRO Processing . . . . . . . . . . . . . . . . . . . 14 91 5.5. METRIC Object . . . . . . . . . . . . . . . . . . . . . . 14 92 6. Backward Compatibility . . . . . . . . . . . . . . . . . . . 15 93 7. Management Considerations . . . . . . . . . . . . . . . . . . 15 94 7.1. Policy . . . . . . . . . . . . . . . . . . . . . . . . . 15 95 7.2. The PCEP Data Model . . . . . . . . . . . . . . . . . . . 15 97 8. Security Considerations . . . . . . . . . . . . . . . . . . . 15 98 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 99 9.1. PCEP Objects . . . . . . . . . . . . . . . . . . . . . . 16 100 9.2. PCEP-Error Object . . . . . . . . . . . . . . . . . . . . 16 101 9.3. PCEP TLV Type Indicators . . . . . . . . . . . . . . . . 17 102 9.4. New Path Setup Type . . . . . . . . . . . . . . . . . . . 17 103 9.5. New Metric Type . . . . . . . . . . . . . . . . . . . . . 17 104 10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 17 105 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 17 106 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 17 107 12.1. Normative References . . . . . . . . . . . . . . . . . . 18 108 12.2. Informative References . . . . . . . . . . . . . . . . . 19 109 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19 111 1. Introduction 113 SR technology leverages the source routing and tunneling paradigms. 114 A source node can choose a path without relying on hop-by-hop 115 signaling protocols such as LDP or RSVP-TE. Each path is specified 116 as a set of "segments" advertised by link-state routing protocols 117 (IS-IS or OSPF). [I-D.filsfils-rtgwg-segment-routing] provides an 118 introduction to SR architecture. The corresponding IS-IS and OSPF 119 extensions are specified in 120 [I-D.ietf-isis-segment-routing-extensions] and 121 [I-D.ietf-ospf-segment-routing-extensions], respectively. SR 122 architecture defines a "segment" as a piece of information advertised 123 by a link-state routing protocols, e.g. an IGP prefix or an IGP 124 adjacency. Several types of segments are defined. A Node segment 125 represents an ECMP-aware shortest-path computed by IGP to a specific 126 node, and is always global within SR/IGP domain. An Adjacency 127 Segment represents unidirectional adjacency. An Adjacency Segment is 128 local to the node which advertises it. Both Node segments and 129 Adjacency segments can be used for SR Traffic Engineering (SR-TE). 131 The SR architecture can be applied to the MPLS forwarding plane 132 without any change, in which case an SR path corresponds to an MPLS 133 Label Switching Path (LSP). This document is relevant to only MPLS 134 forwarding plane, and assumes that a 32-bit Segment Identifier (SID) 135 represents an absolute value of MPLS label entry. In this document, 136 "Node-SID" and "Adjacency-SID" denote Node Segment Identifier and 137 Adjacency Segment Identifier respectively. 139 A Segment Routed path (SR path) can be derived from an IGP Shortest 140 Path Tree (SPT). SR-TE paths may not follow IGP SPT. Such paths may 141 be chosen by a suitable network planning tool and provisioned on the 142 source node of the SR-TE path. 144 [RFC5440] describes Path Computation Element Protocol (PCEP) for 145 communication between a Path Computation Client (PCC) and a Path 146 Computation Element (PCE) or between one a pair of PCEs. A PCE or a 147 PCC operating as a PCE (in hierarchical PCE environment) computes 148 paths for MPLS Traffic Engineering LSPs (MPLS-TE LSPs) based on 149 various constraints and optimization criteria. 150 [I-D.ietf-pce-stateful-pce] specifies extensions to PCEP that allow a 151 stateful PCE to compute and recommend network paths in compliance 152 with [RFC4657] and defines objects and TLVs for MPLS-TE LSPs. 153 Stateful PCEP extensions provide synchronization of LSP state between 154 a PCC and a PCE or between a pair of PCEs, delegation of LSP control, 155 reporting of LSP state from a PCC to a PCE, controlling the setup and 156 path routing of an LSP from a PCE to a PCC. Stateful PCEP extensions 157 are intended for an operational model in which LSPs are configured on 158 the PCC, and control over them is delegated to the PCE. 160 A mechanism to dynamically initiate LSPs on a PCC based on the 161 requests from a stateful PCE or a controller using stateful PCE is 162 specified in [I-D.ietf-pce-pce-initiated-lsp]. Such mechanism is 163 useful in Software Driven Networks (SDN) applications, such as demand 164 engineering, or bandwidth calendaring. 166 It is possible to use a stateful PCE for computing one or more SR-TE 167 paths taking into account various constraints and objective 168 functions. Once a path is chosen, the stateful PCE can initiate an 169 SR-TE path on a PCC using PCEP extensions specified in 170 [I-D.ietf-pce-pce-initiated-lsp] using the SR specific PCEP 171 extensions described in this document. Additionally, using 172 procedures described in this document, a PCC can request an SR path 173 from either stateful or a stateless PCE. This specification relies 174 on the PATH-SETUP-TYPE TLV and procedures specified in 175 [I-D.ietf-pce-lsp-setup-type]. 177 2. Terminology 179 The following terminologies are used in this document: 181 ERO: Explicit Route Object 183 IGP: Interior Gateway Protocol 185 IS-IS: Intermediate System to Intermediate System 187 LSR: Label Switching Router 189 MSD: Maximum SID Depth 191 NAI: Node or Adjacency Identifier 192 OSPF: Open Shortest Path First 194 PCC: Path Computation Client 196 PCE: Path Computation Element 198 PCEP: Path Computation Element Protocol 200 RRO: Record Route Object 202 SID: Segment Identifier 204 SR: Segment Routing 206 SR-TE: Segment Routed Traffic Engineering 208 TED: Traffic Engineering Database 210 3. Overview of PCEP Operation in SR Networks 212 In SR networks, an ingress node of an SR path appends all outgoing 213 packets with an SR header consisting of a list of SIDs (or MPLS 214 labels in the context of this document). The header has all 215 necessary information to guide the packets from the ingress node to 216 the egress node of the path, and hence there is no need for any 217 signaling protocol. 219 In a PCEP session, LSP information is carried in the Explicit Route 220 Object (ERO), which consists of a sequence of subobjects. Various 221 types of ERO subobjects have been specified in [RFC3209], [RFC3473], 222 and [RFC3477]. In SR networks, an ingress node of an SR path appends 223 all outgoing packets with an SR header consisting of a list of SIDs 224 (or MPLS labels in the context of this document). SR-TE LSPs 225 computed by a PCE can be represented in one of the following forms: 227 o An ordered set of IP address(es) representing network nodes/links: 228 In this case, the PCC needs to convert the IP address(es) into the 229 corresponding MPLS labels by consulting its Traffic Engineering 230 Database (TED). 232 o An ordered set of SID(s). 234 o An ordered set of both MPLS label(s) and IP address(es): In this 235 case, the PCC needs to convert the IP address(es) into the 236 corresponding SID(s) by consulting its TED. 238 This document defines a new ERO subobject denoted by "SR-ERO 239 subobject" capable of carrying a SID as well as the identity of the 240 node/adjacency represented by the SID. SR-capable PCEP speakers 241 should be able to generate and/or process such ERO subobject. An ERO 242 containing SR-ERO subobjects can be included in the PCEP Path 243 Computation Reply (PCRep) message defined in [RFC5440], the PCEP LSP 244 Initiate Request message (PCInitiate) defined in 245 [I-D.ietf-pce-pce-initiated-lsp], as well as in the PCEP LSP Update 246 Request (PCUpd) and PCEP LSP State Report (PCRpt) messages defined in 247 defined in [I-D.ietf-pce-stateful-pce]. 249 When a PCEP session between a PCC and a PCE is established, both PCEP 250 speakers exchange information to indicate their ability to support 251 SR-specific functionality. Furthermore, an LSP initially established 252 via RSVP-TE signaling can be updated with SR-TE path. This 253 capability is useful when a network is migrated from RSVP-TE to SR-TE 254 technology. Similarly, an LSP initially created with SR-TE path can 255 updated to signal the LSP using RSVP-TE if necessary. 257 A PCC MAY include an RRO object containing the recorded LSP in PCReq 258 and PCRpt messages as specified in [RFC5440] and 259 [I-D.ietf-pce-stateful-pce] respectively. This document defines a 260 new RRO subobject for SR networks. Methods used by a PCC to record 261 SR-TE LSP are outside the scope of this document. 263 In summary, this document: 265 o Defines a new PCEP capability, new ERO subobject, new RRO 266 subobject, a new TLV, and new PCEP error codes. 268 o Specifies how two PCEP speakers can establish a PCEP session that 269 can carry information about SR-TE paths. 271 o Specifies processing rules of ERO subobject. 273 o Defines a new path setup type carried in the PATH-SETUP-TYPE TLV 274 for SR-TE LSP. 276 The extensions specified in this document complement the existing 277 PCEP specifications to support SR-TE path. As such, the PCEP 278 messages (e.g., Path Computation Request, Path Computation Reply, 279 Path Computation Report, Path Computation Update, Path Computation 280 Initiate, etc.,) MUST be formatted according to [RFC5440], 281 [I-D.ietf-pce-stateful-pce], [I-D.ietf-pce-pce-initiated-lsp], and 282 any other applicable PCEP specifications. 284 4. SR-Specific PCEP Message Extensions 286 As defined in [RFC5440], a PCEP message consists of a common header 287 followed by a variable length body made up of mandatory and/or 288 optional objects. This document does not require any changes in the 289 format of PCReq and PCRep messages specified in [RFC5440], PCInitiate 290 message specified in [I-D.ietf-pce-pce-initiated-lsp], and PCRpt and 291 PCUpd messages specified in [I-D.ietf-pce-stateful-pce]. However, 292 PCEP messages pertaining to SR-TE LSP MUST include PATH-SETUP-TYPE 293 TLV in the RP or SRP object to clearly identify that SR-TE LSP is 294 intended. In other words, a PCEP speaker MUST not infer whether or 295 not a PCEP message pertains to SR-TE LSP from any other object or 296 TLV. 298 5. Object Formats 300 5.1. The OPEN Object 302 This document defines a new optional TLV for use in the OPEN Object. 304 5.1.1. The SR PCE Capability TLV 306 The SR-PCE-CAPABILITY TLV is an optional TLV associated with the OPEN 307 Object to exchange SR capability of PCEP speakers. The format of the 308 SR-PCE-CAPABILITY TLV is shown in the following figure: 310 0 1 2 3 311 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 1 312 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 313 | Type=TBD | Length=4 | 314 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 315 | Reserved | Flags | MSD | 316 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 318 Figure 1: SR-PCE-CAPABILITY TLV format 320 The code point for the TLV type is to be defined by IANA. The TLV 321 length is 4 octets. 323 The 32-bit value is formatted as follows. The "Maximum SID Depth" (1 324 octet) field (MSD) specifies the maximum number of SIDs that a PCC is 325 capable of imposing on a packet. The "Flags" (1 octet) and 326 "Reserved" (2 octets) fields are currently unused, and MUST be set to 327 zero on transmission and ignored on reception. 329 5.1.1.1. Exchanging SR Capability 331 By including the SR-PCE-CAPABILITY TLV in the OPEN message destined 332 to a PCE, a PCC indicates that it is capable of supporting the head- 333 end functions for SR-TE LSP. By including the TLV in the OPEN 334 message destined to a PCC, a PCE indicates that it is capable of 335 computing SR-TE paths. 337 The number of SIDs that can be imposed on a packet depends on PCC's 338 data plane's capability. An MSD value of zero means that a PCC does 339 not impose any default limitation on the number of SIDs included in 340 any SR-TE path coming from PCE. Once an SR-capable PCEP session is 341 established with a non-zero MSD value, the corresponding PCE MUST NOT 342 send SR-TE paths with SIDs exceeding that MSD value. If a PCC needs 343 to modify the MSD value, the PCEP session MUST be closed and re- 344 established with the new MSD value. If a PCEP session is established 345 with a non-zero MSD value, and the PCC receives an SR-TE path 346 containing more SIDs than specified in the MSD value, the PCC MUST 347 send a PCErr message with Error-Type 10 (Reception of an invalid 348 object) and Error-Value 3 (Unsupported number of Segment ERO). If a 349 PCEP session is established with an MSD value of zero, then the PCC 350 MAY specify an MSD for each path computation request that it sends to 351 the PCE. 353 The SR Capability TLV is meaningful only in the OPEN message sent 354 from a PCC to a PCE. As such, a PCE does not need to set MSD value 355 in outbound message to a PCC. Similarly, a PCC ignores any MSD value 356 received from a PCE. If a PCE receives multiple SR-PCE-CAPABILITY 357 TLVs in an OPEN message, it processes only the first TLV is 358 processed. 360 5.2. The RP/SRP Object 362 In order to setup an SR-TE LSP using SR, RP or SRP object MUST PATH- 363 SETUP-TYPE TLV specified in [I-D.ietf-pce-lsp-setup-type]. This 364 document defines a new Path Setup Type (PST) for SR as follows: 366 o PST = 1: Path is setup using Segment Routing Traffic Engineering 367 technique. 369 5.3. ERO Object 371 An SR-TE path consists of one or more SID(s) where each SID MAY be 372 associated with the identifier that represents the node or adjacency 373 corresponding to the SID. This identifier is referred to as the 374 'Node or Adjacency Identifier' (NAI). As described later, a NAI can 375 be represented in various formats (e.g., IPv4 address, IPv6 address, 376 etc). Furthermore, a NAI is used for troubleshooting purposes and, 377 if necessary, to derive SID value as described below. 379 The ERO object specified in [RFC5440] is used to carry SR-TE path 380 information. In order to carry SID and/or NAI, this document defines 381 a new ERO subobject referred to as "SR-ERO subobject" whose format is 382 specified in the following section. An ERO object carrying an SR-TE 383 path consists of one or more ERO subobject(s), and MUST carry only 384 SR-ERO subobject. Note that an SR-ERO subobject does not need to 385 have both SID and NAI. However, at least one of them MUST be 386 present. 388 When building the MPLS label stack from ERO, a PCC MUST assume that 389 SR-ERO subobjects are organized as a last-in-first-out stack. The 390 first subobject relative to the beginning of ERO contains the 391 information about the topmost label. The last subobject contains 392 information about the bottommost label. 394 5.3.1. SR-ERO Subobject 396 An SR-ERO subobject consists of a 32-bit header followed by the SID 397 and the NAI associated with the SID. The SID is a 32-bit number. 398 The size of the NAI depends on its respective type, as described in 399 the following sections. 401 0 1 2 3 402 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 1 403 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 404 |L| Type | Length | ST | Flags |F|S|C|M| 405 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 406 | SID | 407 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 408 // NAI (variable) // 409 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 411 Figure 2: SR-ERO Subobject format 413 The fields in the SR-ERO Subobject are as follows: 415 The 'L' Flag indicates whether the subobject represents a loose-hop 416 in the LSP [RFC3209]. If this flag is unset, a PCC MUST not 417 overwrite the SID value present in the SR-ERO subobject. 418 Otherwise, a PCC MAY expand or replace one or more SID value(s) in 419 the received SR-ERO based on its local policy. 421 Type is the type of the SR-ERO subobject. This document defines the 422 SR-ERO subobject type, and requests a new codepoint from IANA. 424 Length contains the total length of the subobject in octets, 425 including the L, Type and Length fields. Length MUST be at least 426 8, and MUST be a multiple of 4. As mentioned earlier, an SR-ERO 427 subobject MUST have at least SID or NAI. The length should take 428 into consideration SID or NAI only if they are not null. The 429 flags described below used to indicate whether SID or NAI field is 430 null. 432 SID Type (ST) indicates the type of information associated with the 433 SID contained in the object body. When ST value is 0, SID MUST 434 NOT be null and NAI MUST be null. Other ST values are described 435 later in this document. 437 Flags is used to carry any additional information pertaining to SID. 438 Currently, the following flag bits are defined: 440 * M: When this bit is set, the SID value represents an MPLS label 441 stack entry as specified in [RFC5462] where only the label 442 value is specified by the PCE. Other fields (TC, S, and TTL) 443 fields MUST be considered invalid, and PCC MUST set these 444 fields according to its local policy and MPLS forwarding rules. 446 * C: When this bit as well as the M bit are set, then the SID 447 value represents an MPLS label stack entry as specified in 448 [RFC5462], where all the entry's fields (Label, TC, S, and TTL) 449 are specified by the PCE. However, a PCC MAY choose to 450 override TC, S, and TTL values according its local policy and 451 MPLS forwarding rules. 453 * S: When this bit is set, the SID value in the subobject body is 454 null. In this case, the PCC is responsible for choosing the 455 SID value, e.g., by looking up its TED using the NAI which, in 456 this case, MUST be present in the subobject. 458 * F: When this bit is set, the NAI value in the subobject body is 459 null. 461 SID is the Segment Identifier. 463 NAI contains the NAI associated with the SID. Depending on the 464 value of ST, the NAI can have different format as described in the 465 following section. 467 5.3.2. NAI Associated with SID 469 This document defines the following NAIs: 471 'IPv4 Node ID' is specified as an IPv4 address. In this case, ST 472 value is 1, and the Length is 8 or 12 depending on either SID or 473 NAI or both are included in the subobject. 475 'IPv6 Node ID' is specified as an IPv6 address. In this case, ST 476 and Length are 2, and Length is 8, 20, or 24 depending on either 477 SID or NAI or both are included in the subobject. 479 'IPv4 Adjacency' is specified as a pair of IPv4 addresses. In this 480 case, ST value is 3. The Length is 8, 12, or 16 depending on 481 either SID or NAI or both are included in the subobject, and the 482 format of the NAI is shown in the following figure: 484 0 1 2 3 485 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 1 486 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 487 | Local IPv4 address | 488 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 489 | Remote IPv4 address | 490 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 492 Figure 3: NAI for IPv4 Adjacency 494 'IPv6 Adjacency' is specified as a pair of IPv6 addresses. In this 495 case, ST valie is 4. The Length is 8, 36 or 40 depending on 496 whether SID or NAI or both included in the subobject,and the 497 format of the NAI is shown in the following figure: 499 0 1 2 3 500 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 1 501 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 502 // Local IPv6 address (16 bytes) // 503 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 504 // Remote IPv6 address (16 bytes) // 505 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 507 Figure 4: NAI for IPv6 adjacenc y 509 'Unnumbered Adjacency with IPv4 NodeIDs' is specified as a pair of 510 Node ID / Interface ID tuples. In this case, ST value is 5. The 511 Length is 8, 20, or 24 depending on whether SID or NAI or both 512 included in the subobject, and the format of the NAI is shown in 513 the following figure: 515 0 1 2 3 516 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 1 517 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 518 | Local Node-ID | 519 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 520 | Local Interface ID | 521 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 522 | Remote Node-ID | 523 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 524 | Remote Interface ID | 525 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 527 Figure 5: NAI for Unnumbered adjacency with IPv4 Node IDs 529 Editorial Note: We are yet to decide if another SID subobject is 530 required for unnumbered adjacency with 128 bit node ID. 532 5.3.3. ERO Processing 534 A PCEP speaker that does not recognize the SR-ERO subobject in PCRep, 535 PCInitiate, PCUpd or PCRpt messages MUST reject the entire PCEP 536 message and MUST send a PCErr message with Error-Type=3 ("Unknown 537 Object") and Error-Value=2 ("Unrecognized object Type") or Error- 538 Type=4 ("Not supported object") and Error-Value=2 ("Not supported 539 object Type"), defined in [RFC5440]. 541 When the SID represents an MPLS label (i.e. the M bit is set), its 542 value (20 most significant bits) MUST be larger than 15, unless it is 543 special purpose label, such as an Entropy Label Indicator (ELI). If 544 a PCEP speaker receives a label ERO subobject with an invalid value, 545 it MUST send a PCErr message with Error-Type = 10 ("Reception of an 546 invalid object") and Error Value = TBD ("Bad label value"). If both 547 M and C bits of an ERO subobject are set, and if a PCEP speaker finds 548 erroneous setting in one or more of TC, S, and TTL fields, it MUST 549 send a PCErr message with Error-Type = 10 ("Reception of an invalid 550 object") and Error-Value = TBD ("Bad label format"). 552 If a PCC receives a stack of SR-ERO subobjects, and the number of 553 stack exceeds the maximum number of SIDs that the PCC can impose on 554 the packet, it MAY send a PCErr message with Error-Type = 10 555 ("Reception of an invalid object") and Error-Value = TBD 556 ("Unsupported number of Segment ERO subobjects"). 558 When a PCEP speaker detects that all subobjects of ERO are not 559 identical, and if it does not handle such ERO, it MUST send a PCErr 560 message with Error-Type = 10 ("Reception of an invalid object") and 561 Error-Value = TBD ("Non-identical ERO subobjects"). 563 If a PCEP speaker receives an SR-ERO subobject in which both SID and 564 NAI are absent, it MUST consider the entire ERO object invalid and 565 send a PCErr message with Error-Type = 10 ("Reception of an invalid 566 object") and Error-Value = TBD ("Both SID and NAI are absent in ERO 567 subobject"). 569 When a PCEP speaker receives an SR-ERO subobject in which ST is 0, 570 SID MUST be present and NAI MUST NOT be present(i.e., S-flag MUST be 571 0, F-flag MUST be 1, and the Length MUST be 8). Otherwise, it MUST 572 consider the entire ERO object invalid and send a PCErr message with 573 Error-Type = 10 ("Reception of an invalid object") and Error-Value = 574 TBD ("Malformed object"). The PCEP speaker MAY include the malformed 575 SR-ERO object in the PCErr message as well. 577 5.4. RRO Object 579 A PCC can record SR-TE LSP and report the LSP to a PCE via RRO. An 580 RRO object contains one or more subobjects called "SR-RRO subobjects" 581 whose format is shown below: 583 0 1 2 3 584 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 1 585 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 586 | Type | Length | ST | Flags |F|S|C|M| 587 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 588 | SID | 589 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 590 // NAI (variable) // 591 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 593 Figure 6: SR-RRO Subobject format 595 The format of SR-RRO subobject is the same as that of SR-ERO 596 subobject without L flag. 598 A PCC MUST assume that SR-RRO subobjects are organized such that the 599 first subobject relative to the beginning of RRO contains the 600 information about the topmost label, and the last subobject contains 601 information about the bottommost label of the SR-TE LSP. 603 5.4.1. RRO Processing 605 Processing rules of SR-RRO subobject are identical to those of SR-ERO 606 subobject. 608 If a PCEP speaker receives an SR-RRO subobject in which both SID and 609 NAI are absent, it MUST consider the entire RRO object invalid and 610 send a PCErr message with Error-Type = 10 ("Reception of an invalid 611 object") and Error-Value = TBD ("Both SID and NAI are absent in RRO 612 subobject"). 614 If a PCE detects that all subobjects of RRO are not identical, and if 615 it does not handle such RRO, it MUST send a PCErr message with Error- 616 Type = 10 ("Reception of an invalid object") and Error-Value = TBD 617 ("Non-identical RRO subobjects"). 619 5.5. METRIC Object 621 If a PCEP session is established with an MSD value of zero, then the 622 PCC MAY specify the MSD for an individual path computation request 623 using the METRIC object defined in [RFC5440]. This document defines 624 a new type for the METRIC object to be used for this purpose as 625 follows: 627 o T = TBD (suggested value 11): Maximum SID Depth of the requested 628 path. 630 The PCC sets the metric-value to the MSD for this path. The PCC MUST 631 set the B (bound) bit to 1 in the METRIC object, which specifies that 632 the SID depth for the computed path MUST NOT exceed the metric-value. 634 If a PCEP session is established with a non-zero MSD value, then the 635 PCC MUST NOT send an MSD METRIC object. If the PCE receives a path 636 computation request with an MSD METRIC object on a session with a 637 non-zero MSD value then it MUST consider the request invalid and send 638 a PCErr with Error-Type = 10 ("Reception of an invalid object") and 639 Error-Value TBD ("Default MSD is specified for the PCEP session"). 641 6. Backward Compatibility 643 A PCEP speaker that does not support the SR PCEP capability cannot 644 recognize the SR-ERO or SR-RRO subobjects. As such, it MUST send a 645 PCEP error with Error-Type = 4 (Not supported object) and Error-Value 646 = 2 (Not supported object Type) as per [RFC5440]. 648 7. Management Considerations 650 7.1. Policy 652 PCEP implementation: 654 o Can enable SR PCEP capability either by default or via explicit 655 configuration. 657 o May generate PCEP error due to unsupported number of SR-ERO or SR- 658 RRO subobjects either by default or via explicit configuration. 660 7.2. The PCEP Data Model 662 A PCEP MIB module is defined in [I-D.ietf-pce-pcep-mib] needs be 663 extended to cover additional functionality provided by [RFC5440] and 664 [I-D.ietf-pce-pce-initiated-lsp]. Such extension will cover the new 665 functionality specified in this document. 667 8. Security Considerations 669 The security considerations described in [RFC5440] and 670 [I-D.ietf-pce-pce-initiated-lsp] are applicable to this 671 specification. No additional security measure is required. 673 9. IANA Considerations 674 9.1. PCEP Objects 676 This document defines a new sub-object type for the PCEP explicit 677 route object (ERO), and a new sub-object type for the PCEP record 678 route object (RRO). The code points for sub-object types of these 679 objects is maintained in the RSVP parameters registry, under the 680 EXPLICIT_ROUTE and ROUTE_RECORD objects. IANA is requested to 681 allocate code points in the RSVP Parameters registry for each of the 682 new sub-object types defined in this document, as follows: 684 Object Sub-Object Sub-Object Type 685 --------------------- -------------------------- ------------------ 686 EXPLICIT_ROUTE SR-ERO (PCEP-specific) TBD (recommended 36) 687 ROUTE_RECORD SR-RRO (PCEP-specific) TBD (recommended 36) 689 9.2. PCEP-Error Object 691 IANA is requested to allocate code-points in the PCEP-ERROR Object 692 Error Types and Values registry for the following new error-values: 694 Error-Type Meaning 695 ---------- ------- 696 10 Reception of an invalid object. 698 Error-value = TBD (recommended 2): Bad label value 699 Error-value = TBD (recommended 3): Unsupported number 700 of Segment ERO 701 subobjects 702 Error-value = TBD (recommended 4): Bad label format 703 Error-value = TBD (recommended 5): Non-identical ERO 704 subobjects 705 Error-value = TBD (recommended 6): Both SID and NAI 706 are absent in ERO 707 subobject 708 Error-value = TBD (recommended 7): Both SID and NAI 709 are absent in RRO 710 subobject 711 Error-value = TBD (recommended 9): Default MSD is 712 specified for the 713 PCEP session 714 Error-value = TBD (recommended 10): Non-identical RRO 715 subobjects 716 Error-value = TBD (recommended 11): Malformed object 718 9.3. PCEP TLV Type Indicators 720 IANA is requested to allocate a new code point in the PCEP TLV Type 721 Indicators registry, as follows: 723 Value Meaning Reference 724 ------------------------- ---------------------------- -------------- 725 TBD (recommended 26) SR-PCE-CAPABILITY This document 727 9.4. New Path Setup Type 729 [I-D.ietf-pce-lsp-setup-type] defines the PATH-SETUP-TYPE TLV and 730 requests that IANA creates a registry to manage the value of the 731 PATH_SETUP_TYPE TLV's PST field. IANA is requested to allocate a new 732 code point in the PCEP PATH_SETUP_TYPE TLV PST field registry, as 733 follows: 735 Value Description Reference 736 ------------------------- ---------------------------- -------------- 737 1 Traffic engineering path is This document 738 setup using Segment Routing 739 technique. 741 9.5. New Metric Type 743 IANA is requested to allocate a new code point in the PCEP METRIC 744 object T field registry, as follows: 746 Value Description Reference 747 ------------------------- ---------------------------- -------------- 748 TBD (recommended 11) Segment-ID (SID) Depth. This document 750 10. Contributors 752 The following people contributed to this document: 754 - Lakshmi Sharma 756 11. Acknowledgements 758 We like to thank Ina Minei, George Swallow, Marek Zavodsky and Tomas 759 Janciga for the valuable comments. 761 12. References 762 12.1. Normative References 764 [I-D.filsfils-rtgwg-segment-routing] 765 Filsfils, C., Previdi, S., Bashandy, A., Decraene, B., 766 Litkowski, S., Horneffer, M., Milojevic, I., Shakir, R., 767 Ytti, S., Henderickx, W., Tantsura, J., and E. Crabbe, 768 "Segment Routing Architecture", draft-filsfils-rtgwg- 769 segment-routing-01 (work in progress), October 2013. 771 [I-D.ietf-isis-segment-routing-extensions] 772 Previdi, S., Filsfils, C., Bashandy, A., Gredler, H., 773 Litkowski, S., and J. Tantsura, "IS-IS Extensions for 774 Segment Routing", draft-ietf-isis-segment-routing- 775 extensions-00 (work in progress), April 2014. 777 [I-D.ietf-ospf-segment-routing-extensions] 778 Psenak, P., Previdi, S., Filsfils, C., Gredler, H., 779 Shakir, R., Henderickx, W., and J. Tantsura, "OSPF 780 Extensions for Segment Routing", draft-ietf-ospf-segment- 781 routing-extensions-00 (work in progress), June 2014. 783 [I-D.ietf-pce-lsp-setup-type] 784 Sivabalan, S., Medved, J., Minei, I., Crabbe, E., and R. 785 Varga, "Conveying path setup type in PCEP messages", 786 draft-ietf-pce-lsp-setup-type-00 (work in progress), 787 October 2014. 789 [I-D.ietf-pce-pce-initiated-lsp] 790 Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "PCEP 791 Extensions for PCE-initiated LSP Setup in a Stateful PCE 792 Model", draft-ietf-pce-pce-initiated-lsp-01 (work in 793 progress), June 2014. 795 [I-D.ietf-pce-pcep-mib] 796 Koushik, K., Stephan, E., Zhao, Q., King, D., and J. 797 Hardwick, "PCE communication protocol (PCEP) Management 798 Information Base", draft-ietf-pce-pcep-mib-04 (work in 799 progress), February 2013. 801 [I-D.ietf-pce-stateful-pce] 802 Crabbe, E., Medved, J., Minei, I., and R. Varga, "PCEP 803 Extensions for Stateful PCE", draft-ietf-pce-stateful- 804 pce-05 (work in progress), July 2013. 806 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 807 Requirement Levels", BCP 14, RFC 2119, 808 DOI 10.17487/RFC2119, March 1997, 809 . 811 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 812 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 813 DOI 10.17487/RFC5440, March 2009, 814 . 816 [RFC5462] Andersson, L. and R. Asati, "Multiprotocol Label Switching 817 (MPLS) Label Stack Entry: "EXP" Field Renamed to "Traffic 818 Class" Field", RFC 5462, DOI 10.17487/RFC5462, February 819 2009, . 821 12.2. Informative References 823 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., 824 and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP 825 Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001, 826 . 828 [RFC3473] Berger, L., Ed., "Generalized Multi-Protocol Label 829 Switching (GMPLS) Signaling Resource ReserVation Protocol- 830 Traffic Engineering (RSVP-TE) Extensions", RFC 3473, 831 DOI 10.17487/RFC3473, January 2003, 832 . 834 [RFC3477] Kompella, K. and Y. Rekhter, "Signalling Unnumbered Links 835 in Resource ReSerVation Protocol - Traffic Engineering 836 (RSVP-TE)", RFC 3477, DOI 10.17487/RFC3477, January 2003, 837 . 839 [RFC4657] Ash, J., Ed. and J. Le Roux, Ed., "Path Computation 840 Element (PCE) Communication Protocol Generic 841 Requirements", RFC 4657, DOI 10.17487/RFC4657, September 842 2006, . 844 Authors' Addresses 846 Siva Sivabalan 847 Cisco Systems, Inc. 848 2000 Innovation Drive 849 Kanata, Ontario K2K 3E8 850 Canada 852 Email: msiva@cisco.com 853 Jan Medved 854 Cisco Systems, Inc. 855 170 West Tasman Dr. 856 San Jose, CA 95134 857 US 859 Email: jmedved@cisco.com 861 Clarence Filsfils 862 Cisco Systems, Inc. 863 Pegasus Parc 864 De kleetlaan 6a, DIEGEM BRABANT 1831 865 BELGIUM 867 Email: cfilsfil@cisco.com 869 Edward Crabbe 871 Robert Raszuk 872 Mirantis Inc. 873 100-615 National Ave. 874 Mountain View, CA 94043 875 US 877 Email: robert@raszuk.net 879 Victor Lopez 880 Telefonica I+D 881 Don Ramon de la Cruz 82-84 882 Madrid 28045 883 Spain 885 Email: vlopez@tid.es 887 Jeff Tantsura 888 Ericsson 889 300 Holger Way 890 San Jose, CA 95134 891 USA 893 Email: jeff.tantsura@ericsson.com 894 Wim Henderickx 895 Alcatel Lucent 896 Copernicuslaan 50 897 Antwerp 2018, CA 95134 898 BELGIUM 900 Email: wim.henderickx@alcatel-lucent.com 902 Jon Hardwick 903 Metaswitch Networks 904 100 Church Street 905 Enfield, Middlesex 906 UK 908 Email: jon.hardwick@metaswitch.com