idnits 2.17.1 draft-ietf-pce-pcep-domain-sequence-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 (July 5, 2012) is 4312 days in the past. Is this intentional? Checking references for intended status: Experimental ---------------------------------------------------------------------------- -- Obsolete informational reference (is this intentional?): RFC 4893 (Obsoleted by RFC 6793) == Outdated reference: A later version (-08) exists of draft-ietf-pce-pcep-inter-domain-p2mp-procedures-02 == Outdated reference: A later version (-05) exists of draft-ietf-pce-hierarchy-fwk-04 == Outdated reference: A later version (-12) exists of draft-dhody-pce-pcep-p2mp-per-destination-01 Summary: 0 errors (**), 0 flaws (~~), 4 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 PCE Working Group D. Dhody 3 Internet-Draft U. Palle 4 Intended status: Experimental Huawei Technologies India Pvt 5 Expires: January 6, 2013 Ltd 6 R. Casellas 7 CTTC - Centre Tecnologic de 8 Telecomunicacions de Catalunya 9 July 5, 2012 11 Standard Representation Of Domain Sequence 12 draft-ietf-pce-pcep-domain-sequence-01 14 Abstract 16 The ability to compute shortest constrained Traffic Engineering Label 17 Switched Paths (TE LSPs) in Multiprotocol Label Switching (MPLS) and 18 Generalized MPLS (GMPLS) networks across multiple domains has been 19 identified as a key requirement for P2P and P2MP scenarios. In this 20 context, a domain is a collection of network elements within a common 21 sphere of address management or path computational responsibility 22 such as an IGP area or an Autonomous Systems. This document 23 specifies a standard representation and encoding of a domain 24 sequence, which is defined as an ordered sequence of domains 25 traversed to reach the destination domain. This document also 26 defines new sub-objects to be used to encode domain identifiers. 28 Status of This Memo 30 This Internet-Draft is submitted in full conformance with the 31 provisions of BCP 78 and BCP 79. 33 Internet-Drafts are working documents of the Internet Engineering 34 Task Force (IETF). Note that other groups may also distribute 35 working documents as Internet-Drafts. The list of current Internet- 36 Drafts is at http://datatracker.ietf.org/drafts/current/. 38 Internet-Drafts are draft documents valid for a maximum of six months 39 and may be updated, replaced, or obsoleted by other documents at any 40 time. It is inappropriate to use Internet-Drafts as reference 41 material or to cite them other than as "work in progress." 43 This Internet-Draft will expire on January 6, 2013. 45 Copyright Notice 47 Copyright (c) 2012 IETF Trust and the persons identified as the 48 document authors. All rights reserved. 50 This document is subject to BCP 78 and the IETF Trust's Legal 51 Provisions Relating to IETF Documents 52 (http://trustee.ietf.org/license-info) in effect on the date of 53 publication of this document. Please review these documents 54 carefully, as they describe your rights and restrictions with respect 55 to this document. Code Components extracted from this document must 56 include Simplified BSD License text as described in Section 4.e of 57 the Trust Legal Provisions and are provided without warranty as 58 described in the Simplified BSD License. 60 Table of Contents 62 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 63 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4 64 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 65 3. Detail Description . . . . . . . . . . . . . . . . . . . . . . 6 66 3.1. Domains . . . . . . . . . . . . . . . . . . . . . . . . . 6 67 3.2. Domain-Sequence . . . . . . . . . . . . . . . . . . . . . 6 68 3.3. Standard Representation . . . . . . . . . . . . . . . . . 7 69 3.3.1. New Sub-Objects . . . . . . . . . . . . . . . . . . . 7 70 3.3.1.1. Autonomous system . . . . . . . . . . . . . . . . 7 71 3.3.1.2. IGP Area . . . . . . . . . . . . . . . . . . . . . 8 72 3.3.2. Use in PCEP Objects . . . . . . . . . . . . . . . . . 9 73 3.3.2.1. Include Route Object . . . . . . . . . . . . . . . 9 74 3.3.2.2. Exclude Route Object . . . . . . . . . . . . . . . 13 75 3.3.2.3. Explicit Route Object . . . . . . . . . . . . . . 15 76 3.3.2.4. Explicit Exclusion Route Sub-Object . . . . . . . 16 77 3.4. Other Considerations . . . . . . . . . . . . . . . . . . . 16 78 3.4.1. Inter-Area Path Computation . . . . . . . . . . . . . 16 79 3.4.2. Inter-AS Path Computation . . . . . . . . . . . . . . 18 80 3.4.2.1. Example 1 . . . . . . . . . . . . . . . . . . . . 18 81 3.4.2.2. Example 2 . . . . . . . . . . . . . . . . . . . . 20 82 3.4.3. Boundary Node and Inter-AS-Link . . . . . . . . . . . 22 83 3.4.4. PCE serving multiple domains . . . . . . . . . . . . . 23 84 3.4.5. P2MP . . . . . . . . . . . . . . . . . . . . . . . . . 23 85 3.4.6. HPCE . . . . . . . . . . . . . . . . . . . . . . . . . 23 86 3.4.7. Relationship to PCE Sequence . . . . . . . . . . . . . 25 87 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25 88 4.1. PCEP Objects . . . . . . . . . . . . . . . . . . . . . . . 25 89 4.2. New Sub-Objects . . . . . . . . . . . . . . . . . . . . . 26 90 4.3. Error Object Field Values . . . . . . . . . . . . . . . . 26 91 5. Security Considerations . . . . . . . . . . . . . . . . . . . 26 92 6. Manageability Considerations . . . . . . . . . . . . . . . . . 27 93 6.1. Control of Function and Policy . . . . . . . . . . . . . . 27 94 6.2. Information and Data Models . . . . . . . . . . . . . . . 27 95 6.3. Liveness Detection and Monitoring . . . . . . . . . . . . 27 96 6.4. Verify Correct Operations . . . . . . . . . . . . . . . . 27 97 6.5. Requirements On Other Protocols . . . . . . . . . . . . . 27 98 6.6. Impact On Network Operations . . . . . . . . . . . . . . . 28 99 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 28 100 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 28 101 8.1. Normative References . . . . . . . . . . . . . . . . . . . 28 102 8.2. Informative References . . . . . . . . . . . . . . . . . . 28 104 1. Introduction 106 A PCE may be used to compute end-to-end paths across multi-domain 107 environments using a per-domain path computation technique [RFC5152]. 108 The so called backward recursive path computation (BRPC) mechanism 109 [RFC5441] defines a PCE-based path computation procedure to compute 110 inter-domain constrained (G)MPLS TE LSPs. However, both per-domain 111 and BRPC techniques assume that the sequence of domains to be crossed 112 from source to destination is known, either fixed by the network 113 operator or obtained by other means. For inter-domain point-to- 114 multi-point (P2MP) tree, [PCE-P2MP-PROCEDURES] assumes the domain- 115 tree is known. 117 The list of domains in a point-to-point (P2P) path or a point-to- 118 multi-point (P2MP) tree is usually a constraint in the path 119 computation request. The PCE decouples the domain to determine the 120 next PCE to forward the request. 122 According to BRPC mechanism the PCC MAY indicate the sequence of 123 domains to be traversed using the Include Route Object (IRO) defined 124 in [RFC5440]. 126 This document proposes a standard way to represent and encode a 127 domain sequence using IRO in various deployment scenarios including 128 P2P, P2MP and Hierarchical PCE (HPCE) [PCE-HIERARCHY-FWK]. 130 The domain sequence (the set of domains traversed to reach the 131 destination domain) is either administratively predetermined or 132 discovered by some means (H-PCE) that is outside of the scope of this 133 document. Here the focus is only on a standard representation of the 134 domain sequence in all possible scenarios. 136 1.1. Requirements Language 138 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 139 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 140 document are to be interpreted as described in [RFC2119]. 142 2. Terminology 144 The following terminology is used in this document. 146 ABR: OSPF Area Border Router. Routers used to connect two IGP 147 areas. 149 AS: Autonomous System. 151 ASBR: Autonomous System Boundary Router. 153 BN: Boundary Node, Can be an ABR or ASBR. 155 BRPC: Backward Recursive Path Computation 157 Domain: Any collection of network elements within a common sphere of 158 address management or path computational responsibility. Examples 159 of domains include Interior Gateway Protocol (IGP) areas and 160 Autonomous Systems (ASs). 162 Domain-Seq: An ordered sequence of domains traversed to reach the 163 destination domain. 165 ERO: Explicit Route Object 167 H-PCE: Hierarchical PCE 169 IGP: Interior Gateway Protocol. Either of the two routing 170 protocols, Open Shortest Path First (OSPF) or Intermediate System 171 to Intermediate System (IS-IS). 173 IRO: Include Route Object 175 IS-IS: Intermediate System to Intermediate System. 177 OSPF: Open Shortest Path First. 179 PCC: Path Computation Client: any client application requesting a 180 path computation to be performed by a Path Computation Element. 182 PCE: Path Computation Element. An entity (component, application, 183 or network node) that is capable of computing a network path or 184 route based on a network graph and applying computational 185 constraints. 187 P2MP: Point-to-Multipoint 189 P2P: Point-to-Point 191 RSVP: Resource Reservation Protocol 193 TE LSP: Traffic Engineering Label Switched Path. 195 3. Detail Description 197 3.1. Domains 199 A domain can be defined as a separate administrative or geographic 200 environment within the network. A domain may be further defined as a 201 zone of routing or computational ability. Under these definitions a 202 domain might be categorized as an Autonomous System (AS) or an 203 Interior Gateway Protocol (IGP) area ( as per [RFC4726] and 204 [RFC4655]). To uniquely identify a domain in the domain sequence 205 both AS and Area-id MAYBE important. 207 3.2. Domain-Sequence 209 A domain-sequence is an ordered sequence of domains traversed to 210 reach the destination domain. In this context a Domain could be an 211 Autonomous System (AS) or an IGP Area. Note that an AS can be 212 further made of multiple Areas. 214 Domain Sequence can be applied as a constraint and carried in path 215 computation request to PCE(s). In case of HPCE [PCE-HIERARCHY-FWK] 216 Parent PCE MAY send the domain sequence as a result in path 217 computation reply. 219 In this context, ordered sequence is important, in a P2P path, the 220 domains listed appear in the order that they are crossed. In a P2MP 221 path, the domain tree is represented as list of domain sequences. 223 One main goal of the Domain-Sequence is to enable a PCE to select the 224 next PCE to forward the path computation request based on the domain 225 information. 227 A PCC or PCE MAY add an additional constraints covering which 228 Boundary Nodes (ABR or ASBR) or Border links (Inter-AS-link) MUST be 229 traversed while defining a domain sequence. 231 Thus a Domain-Sequence MAY be made up of one or more of - 233 o AS Number 235 o Area ID 237 o Boundary Node ID 239 o Inter-AS-Link Address 241 Consequently, a Domain-Sequence can be used: 243 1. by a PCE in order to discover or select the next PCE in a 244 collaborative path computation, such as in BRPC [RFC5441]; 246 2. by the Parent PCE to return the domain sequence when unknown, 247 this can further be an input to BRPC procedure; 249 3. By a PCC (or PCE) to constraint the domains used in a H-PCE path 250 computation, explicitly specifying which domains to be expanded; 252 3.3. Standard Representation 254 3.3.1. New Sub-Objects 256 Some sub-objects are defined in [RFC3209], [RFC3473], [RFC3477] and 257 [RFC4874], but new sub-objects related to Domain-Sequence are needed. 259 3.3.1.1. Autonomous system 261 [RFC3209] already defines 2 octet AS number. 263 To support 4 octet AS number as per [RFC4893] following subobject is 264 defined: 266 0 1 2 3 267 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 1 268 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 269 |L| Type | Length | Reserved | 270 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 271 | AS Id (4 bytes) | 272 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 274 L: The L bit is an attribute of the subobject as define in [RFC3209]. 276 Type: (TBA by IANA) indicating 4 octet AS Number. 278 Length: 8 (Total length of the subobject in bytes). 280 Reserved: Zero at transmission, Ignored at receipt. 282 AS-ID: The 4 octet AS Number. Note that if 16-bit AS numbers are in 283 use, the low order bits (16 through 31) should be used and the high 284 order bits (0 through 15) should be set to zero. 286 3.3.1.2. IGP Area 288 Since the length and format of Area-id is different for OSPF and 289 ISIS, following two subobjects are defined: 291 For OSPF, the area-id is a 32 bit number. The Subobject looks 292 0 1 2 3 293 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 1 294 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 295 |L| Type | Length | Reserved | 296 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 297 | OSPF Area Id (4 bytes) | 298 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 300 L: The L bit is an attribute of the subobject as define in [RFC3209]. 302 Type: (TBA by IANA) indicating 4 octet OSPF Area ID. 304 Length: 8 (Total length of the subobject in bytes). 306 Reserved: Zero at transmission, Ignored at receipt. 308 OSPF Area Id: The 4 octet OSPF Area ID. 310 For IS-IS, the area-id is of variable length and thus the length of 311 the Subobject is variable. The Area-id is as described in IS-IS by 312 ISO standard [ISO 10589]. 314 0 1 2 3 315 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 1 316 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 317 |L| Type | Length | Area-Len | Reserved | 318 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 319 | | 320 // IS-IS Area ID // 321 | | 322 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 324 L: The L bit is an attribute of the subobject as define in [RFC3209]. 326 Type: (TBA by IANA) indicating IS-IS Area ID. 328 Length: Variable (Total length of the subobject in bytes including 329 padding). The Length MUST be at least 4, and MUST be a multiple of 330 4. 332 Area-Len: Variable (Length of the actual (non-padded) IS-IS Area 333 Identifier in octets; Valid values are from 2 to 11 inclusive). 335 Reserved: Zero at transmission, Ignored at receipt. 337 IS-IS Area Id: The variable-length IS-IS area identifier. Padded 338 with trailing zeroes to a four-octet boundary. 340 3.3.2. Use in PCEP Objects 342 These sub-objects MAYBE used in - 344 o Include Route Object (IRO): As per [RFC5440], used to specify set 345 of network elements that MUST be traversed. These subobjects are 346 used to specify the domain-sequence that MUST be traversed to 347 reach the destination. 349 o Exclude Route Object (XRO): As per [RFC5521], used to specify 350 certain abstract nodes that MUST be excluded from whole path. 351 These subobjects are used to specify certain domains that MUST be 352 avoided to reach the destination. 354 o Explicit Route Object (ERO): As per [RFC5440],used to specify a 355 computed path in the network. These subobjects are used to 356 specify the domain-sequence when computed by a Parent PCE 357 ([PCE-HIERARCHY-FWK]). 359 o Explicit Exclusion Route Sub-Object (EXRS): As per [RFC5521], used 360 to specify exclusion of certain abstract nodes between a specific 361 pair of nodes. EXRS are a sub-object inside the IRO. These 362 subobjects are used to specify the domains that must be excluded 363 between two abstract nodes. 365 3.3.2.1. Include Route Object 367 3.3.2.1.1. Option 1: New IRO Object Type 369 The IRO (Include Route Object) [RFC5440] is an optional object used 370 to specify a set of specified network elements that the computed path 371 MUST traverse. [RFC5440] in its description of IRO does not 372 constrain the sub-objects to be in a given particular order. When 373 considering a domain sequence, the domain relative ordering is a 374 basic criterion and, as such, this document specifies a new IRO 375 object type. 377 We define a new type of IRO Object to define Domain Sequence. 379 IRO Object-Class is 10. 380 IRO Object-Type is TBD. (2 suggested value to IANA) 382 0 1 2 3 383 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 1 384 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 385 | | 386 // (Subobjects) // 387 | | 388 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 390 Sub-objects: The IRO is made of sub-objects identical to the ones 391 defined in [RFC3209], [RFC3473], and [RFC3477], where the IRO sub- 392 object type is identical to the sub-object type defined in the 393 related documents. Some new sub-objects related to Domain-Sequence 394 are also added in this document. 396 The following sub-object types are used. 397 Type Sub-object 398 1 IPv4 prefix 399 2 IPv6 prefix 400 4 Unnumbered Interface ID 401 32 Autonomous system number (2 Byte) 402 33 Explicit Exclusion (EXRS) 403 TBD Autonomous system number (4 Byte) 404 TBD OSPF Area id 405 TBD ISIS Area id 407 [RFC3209] defines sub-objects for IPv4, IPv6 and unnumbered Interface 408 ID, which in the context of domain-sequence is used to specify 409 Boundary Node (ABR/ASBR) and Inter-AS-Links. The sub-objects for AS 410 Number (2 or 4 Byte) and IGP Area is used to specify the domains in 411 the domain-sequence. 413 The new IRO Object-Type used to define the domain-sequence would 414 handle the L bit (Loose / Strict) in the sub-objects. 416 Note that PCReq message is free to carry both type of IRO with IRO 417 Type 1 ([RFC5440]) used to specify the intra-domain abstract nodes 418 and resources and the new IRO Type as described in this document to 419 specify the domain-sequence. 421 All other rules of PCEP objects and message processing (ex. P bit 422 handling of Common Object Header) is as per [RFC5440]. 424 3.3.2.1.1.1. Mode of Operation 426 A domain sequence IRO object constraints or defines the domains 427 involved in a multi-domain path computation, typically involving two 428 or more collaborative PCEs. 430 A domain sequence can have varying degrees on granularity; it is 431 possible to have a domain sequence composed of, uniquely, AS 432 identifiers. It is also possible to list the involved areas for a 433 given AS. 435 In any case, the mapping between domains and responsible PCEs is not 436 defined in this document. It is assumed that a PCE that needs to 437 obtain a "next PCE" from a domain sequence is able to do so (e.g. via 438 administrative configuration, or discovery). 440 A PCC builds a domain sequence IRO (new type) to encode the domain 441 sequence, that is all domains that it wishes the cooperating PCEs to 442 traverse in order to compute the end to end path. 444 For each inclusion, the PCC clears the L-bit to indicate that the PCE 445 is required to include the domain, or sets the L-bit to indicate that 446 the PCC simply desires that the domain be included in the domain- 447 sequence. 449 When a PCE receives a PCReq message it looks for a domain sequence 450 IRO (new type) to see if domain-sequence are required. If the PCE 451 finds more than one domain sequence IRO (new type), it MUST use the 452 first one in the message and MUST ignore subsequent instances. 454 If the PCE does not recognize the domain sequence IRO (new type), it 455 MUST return a PCErr message with Error-Type "Unknown Object" and 456 Error-value "Unrecognized object Type" as described in [RFC5440]. 458 If the PCE is unwilling or unable to process the domain sequence IRO 459 (new type), it MUST return a PCErr message with the Error-Type "Not 460 supported object" and follow the relevant procedures described in 461 [RFC5440]. 463 If a PCE that supports the domain sequence IRO (new type) and 464 encounters a subobject that it does not support or recognize, it MUST 465 act according to the setting of the L-bit in the subobject. If the 466 L-bit is clear, the PCE MUST respond with a PCErr with Error-Type 467 "Unrecognized subobject" and set the Error-Value to the subobject 468 type code. If the L-bit is set, the PCE MAY respond with a PCErr as 469 already stated or MAY ignore the subobject: this choice is a local 470 policy decision. 472 If a PCE parses a domain sequence IRO (new type) and encounters these 473 subobject that it recognizes, it MUST act according to the 474 requirements expressed in the subobject. That is, if the L-bit is 475 clear, the PCE(s) MUST produce a path that follows domain-sequence 476 nodes in order identified by the sub-objects in the path. If the 477 L-bit is set, the PCE(s) SHOULD produce a path along the domain 478 sequence unless it is not possible to construct a path complying with 479 the other constraints expressed in the PCReq message. 481 A successful path computation reported in a PCRep message MUST 482 include an ERO to specify the path that has been computed as 483 specified in [RFC5440] following the domain-sequence. 485 When a PCE returns a path in a PCRep, it MAY also supply a domain 486 sequence IRO (new type) in a PCRep message with the NO-PATH object 487 indicates that the set of elements of the original domain sequence 488 IRO prevented the PCE from finding a path. 490 Sub-Object types for AS and IGP Area guide the next domain selection 491 and finding the PCE serving that domain. 493 Note that a particular domain in the domain-sequence can be 494 identified by - 496 o Just Area: Only the IGP (OSPF or ISIS) Area subobject is used to 497 identify the next domain. (Refer Figure 1) 499 o Just AS: Only the AS subobject is used to identify the next 500 domain. (Refer Figure 2) 502 o AS and IGP Area: Combination of both AS and Area are used to 503 identify the next domain. In this case the order is AS Subobject 504 followed by Area. (Refer Figure 3) 506 Sub-Object of other types representing Boundary Node or Inter-As-Link 507 do not pay any role in selection of next domain and subsequently PCE 508 selection in the domain-sequence. But they MUST be applied during 509 the final path computation procedure as before. 511 3.3.2.1.2. Option 2: Same IRO Object Type 513 The IRO (Include Route Object) [RFC5440] is an optional object used 514 to specify a set of specified network elements that the computed path 515 MUST traverse. 517 The new sub-objects denoting the domain-sequence is carried in the 518 same IRO Type 1, and all the rules of processing as specified in 519 [RFC5440] are applied. 521 Note the following differences - 523 o Order: Since there is no inherent order specified in the encoding 524 of the subobjects in IRO Type 1 [RFC5440]. It is the job of PCE 525 to figure out the order of the domains to be crossed to reach the 526 destination domain. Note that in case of doubt, or when 527 applicable, PCE can still apply the ordering as specified in the 528 PCReq message. 530 o Loose / Strict: [RFC5440] state that the L bit of the sub-objects 531 within an IRO Type 1 [RFC5440] has no meaning. This is applicable 532 for sub-objects denoting domain-sequence as well. 534 o Scope: Sub-objects referring to domains and boundary nodes will 535 mix with subobjects for internal network nodes of multiple 536 domains. It is the job of PCE to figure out the scope and apply 537 the processing rules accordingly. The PCE should distinguish 538 between - the subobject is unknown (not in TED) or known but the 539 computation fails. The PCE processing the IRO MAY include as many 540 of the elements of the IRO as possible. If the PCE is passing the 541 request onwards, it is OK for it to have unknown nodes, and it can 542 assume that the next PCE might be able to satisfy the remaining 543 elements of the IRO. On the other hand, if the PCE is making an 544 end-to-end (or edge-to-edge, or end-to-edge) path and will return 545 the response to a PCC (rather than pass it on) then the PCE must 546 fail if it cannot satisfy the IRO. Ultimately, when the path 547 segments are aggregated by a head-end PCE or by a parent PCE, that 548 PCE can check to see whether any elements of the IRO are still 549 missing and handle accordiangly. 551 3.3.2.2. Exclude Route Object 553 The Exclude Route Object (XRO) [RFC5521] is an optional object used 554 to specify exclusion of certain abstract nodes or resources from the 555 whole path. 557 The following subobject types are defined to be used in XRO as 558 defined in [RFC3209], [RFC3477], [RFC4874], and [RFC5521]. 560 Type Sub-object 561 1 IPv4 prefix 562 2 IPv6 prefix 563 4 Unnumbered Interface ID 564 32 Autonomous system number (2 Byte) 565 34 SRLG 566 64 IPv4 Path Key 567 65 IPv6 Path Key 568 TBD Autonomous system number (4 Byte) 569 TBD OSPF Area id 570 TBD ISIS Area id 572 The new subobjects to support 4 octet AS and IGP (OSPF / ISIS) Area 573 MAY also be used in the XRO to specify exclusion of certain domains 574 in the path computation procedure. 576 The X-bit indicates whether the exclusion is mandatory or desired. 0 577 indicates that the domain specified MUST be excluded from the path 578 computed by the PCE(s). 1 indicates that the domain specified SHOULD 579 be excluded from the inter-domain path computed by the PCE(s), but 580 MAY be included subject to PCE policy and the absence of a viable 581 path that meets the other constraints and excludes the domain. All 582 other fields are consistent with the definition in Section 3.3.1. 584 4 Octet Autonomous system: 586 0 1 2 3 587 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 1 588 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 589 |X| Type | Length | Reserved | 590 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 591 | AS Id (4 bytes) | 592 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 594 OSPF Area: 596 0 1 2 3 597 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 1 598 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 599 |X| Type | Length | Reserved | 600 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 601 | OSPF Area Id (4 bytes) | 602 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 604 IS-IS Area: 606 0 1 2 3 607 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 1 608 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 609 |X| Type | Length | Area-Len | Reserved | 610 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 611 | | 612 // IS-IS Area ID // 613 | | 614 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 616 If a PCE that supports XRO and encounters a subobject that it does 617 not support or recognize, it MUST act according to the setting of the 618 X-bit in the subobject. If the X-bit is clear, the PCE MUST respond 619 with a PCErr with Error-Type "Unrecognized subobject" and set the 620 Error-Value to the subobject type code. If the X-bit is set, the PCE 621 MAY respond with a PCErr as already stated or MAY ignore the 622 subobject: this choice is a local policy decision. 624 All the other processing rules are as per [RFC5521]. 626 3.3.2.3. Explicit Route Object 628 The Explicit Route Object (ERO) [RFC5440] is used to specify a 629 computed path in the network. PCEP ERO sub-object types correspond 630 to RSVP-TE ERO sub-object types as defined in [RFC3209], [RFC3473], 631 [RFC3477], [RFC4873], [RFC4874], and [RFC5520]. 633 Type Sub-object 634 1 IPv4 prefix 635 2 IPv6 prefix 636 3 Label 637 4 Unnumbered Interface ID 638 32 Autonomous system number (2 Byte) 639 33 Explicit Exclusion (EXRS) 640 37 Protection 641 64 IPv4 Path Key 642 65 IPv6 Path Key 643 TBD Autonomous system number (4 Byte) 644 TBD OSPF Area id 645 TBD ISIS Area id 647 The new subobjects to support 4 octet AS and IGP (OSPF / ISIS) Area 648 MAY also be used in the ERO to specify an abstract node (a group of 649 nodes whose internal topology is opaque to the ingress node of the 650 LSP). Using this concept of abstraction, an explicitly routed LSP 651 can be specified as a sequence of domains. 653 In case of Hierarchical PCE, a Parent PCE ([PCE-HIERARCHY-FWK]) MAY 654 be requested to find the domain-sequence. The Parent PCE MUST use 655 ERO with AS and IGP Area subobjects to encode the computed domain- 656 sequence. Refer example in Section 3.4.6. 658 3.3.2.4. Explicit Exclusion Route Sub-Object 660 Explicit Exclusion Route Sub-Object (EXRS) [RFC5521] is used to 661 specify exclusion of certain abstract nodes between a specific pair 662 of nodes. 664 The EXRS subobject may carry any of the subobjects defined for 665 inclusion in the XRO, thus the new subobjects to support 4 octet AS 666 and IGP (OSPF / ISIS) Area MAY also be used in the EXRS. The 667 meanings of the fields of the new XRO subobjects are unchanged when 668 the subobjects are included in an EXRS, except that scope of the 669 exclusion is limited to the single hop between the previous and 670 subsequent elements in the IRO. 672 All the processing rules are as per [RFC5521]. 674 3.4. Other Considerations 676 3.4.1. Inter-Area Path Computation 678 In an inter-area path computation where ingress and egress belong to 679 different IGP area, the domain sequence MAYBE represented using a 680 ordered list of AREA sub-objects. AS number MAYBE skipped, as area 681 information is enough to select the next PCE. 683 +-------------------+ +-------------------+ 684 | | | | 685 | +--+ | | +--+ | 686 | +--+ | | | | | | | 687 | | | +--+ | | +--+ +--+ | 688 | +--* + + | | | 689 | | | +--+ | 690 | *--+ + + | 691 | | | | | +--+ | 692 | +--+ | | | | | 693 | |+--------------------------+| +--+ | 694 | ++++ +-++ | 695 | |||| +--+ | || | 696 | Area 2 ++++ | | +-++ Area 4 | 697 +-------------------+| +--+ |+-------------------+ 698 | | 699 | +--+ | 700 | +--+ | | | 701 | | | +--+ | 702 | +--+ | 703 | | 704 | | 705 | | 706 | | 707 | +--+ | 708 | | | | 709 | +--+ | 710 +------------------+| |+--------------------+ 711 | ++-+ +-++ | 712 | || | | || | 713 | ++-+ Area 0 +-++ | 714 | |+--------------------------+| +--+ | 715 | +--+ | | | | | 716 | | | | | +--+ | 717 | +--+ +--+ | | | 718 | | | + + +--+ | 719 | +--+ | | | | | 720 | + + +--+ | 721 | +--+ | | | 722 | | | | | +--+ | 723 | +--+ | | | | | 724 | | | +--+ | 725 | | | | 726 | Area 1 | | Area 5 | 727 +------------------+ +--------------------+ 729 AS Number is 100. 731 Figure 1: Inter-Area Path Computation 733 This could be represented as as: 735 +---------+ +---------+ +---------+ +---------+ 736 |IRO | |Sub | |Sub | |Sub | 737 |Object | |Object | |Object | |Object | 738 |Header | |Area 2 | |Area 0 | |Area 4 | 739 | | | | | | | | 740 | | | | | | | | 741 +---------+ +---------+ +---------+ +---------+ 743 +---------+ +---------+ +---------+ +---------+ +---------+ 744 |IRO | |Sub | |Sub | |Sub | |Sub | 745 |Object | |Object As| |Object | |Object | |Object | 746 |Header | |100 | |Area 2 | |Area 0 | |Area 4 | 747 | | | | | | | | | | 748 | | | | | | | | | | 749 +---------+ +---------+ +---------+ +---------+ +---------+ 751 AS is optional and it MAY be skipped. PCE should be able to 752 understand both notations. 754 3.4.2. Inter-AS Path Computation 756 In inter-AS path computation, where ingress and egress belong to 757 different AS, the domain sequence is represented using an ordered 758 list of AS sub-objects. The domain sequence MAY further include 759 decomposed area information in AREA sub-objects. 761 3.4.2.1. Example 1 763 As shown in Figure 2, where AS to be made of a single area, the area 764 subobject MAY be skipped in the domain sequence as AS is enough to 765 uniquely identify the next domain and PCE. 767 +---------------------------------+ 768 |AS 200 | 769 | +------+ | 770 | | | | 771 +------------------------+ | | | +------+ | 772 | AS 100 | | +------+ | | | 773 | +------+ | | +------+ | | | 774 | | +-+-----+-+ | +------+ | 775 | | | | | | | | 776 | +------+ | | +------+ | 777 | +------+ | | +------+ | 778 | | | | | | | | 779 | | | | | | | | 780 | +------+ | | +------+ | 781 | | | | 782 | +------+ | | +------+ | 783 | | +-+-----+-+ | +------+ | 784 | | | | | | | | | | 785 | +------+ | | +------+ | | | 786 | | | +------+ | 787 | | | | 788 | | | | 789 | +------+ | | +------+ | 790 | | | | | | | | 791 | |PCE | | | |PCE | | 792 | +------+ | | +------+ | 793 | | | | 794 +------------------------+ | | 795 +---------------------------------+ 797 Both AS are made of Area 0. 799 Figure 2: Inter-AS Path Computation 801 This could be represented as as: 803 +---------+ +---------+ +---------+ 804 |IRO | |Sub | |Sub | 805 |Object | |Object As| |Object As| 806 |Header | |100 | |200 | 807 | | | | | | 808 | | | | | | 809 +---------+ +---------+ +---------+ 811 +---------+ +---------+ +---------+ +---------+ +---------+ 812 |IRO | |Sub | |Sub | |Sub | |Sub | 813 |Object | |Object As| |Object | |Object As| |Object | 814 |Header | |100 | |Area 0 | |200 | |Area 0 | 815 | | | | | | | | | | 816 | | | | | | | | | | 817 +---------+ +---------+ +---------+ +---------+ +---------+ 818 Area is optional and it MAY be skipped. PCE should be able to 819 understand both notations. 821 3.4.2.2. Example 2 823 As shown in Figure 3, where AS 200 is made up of multiple areas and 824 multiple domain-sequence exist, PCE MAY include both AS and AREA 825 subobject to uniquely identify the next domain and PCE. 827 | 828 | +-------------+ +----------------+ 829 | |Area 2 | |Area 4 | 830 | | +--+| | +--+ | 831 | | | || | | | | 832 | | +--+ +--+| | +--+ +--+ | 833 | | | | | | | | | 834 | | *--+ | | +--+ | 835 | | / +--+ | | +--+ | 836 | |/ | | | | | | | 837 | / +--+ | | +--+ +--+ | 838 | /| +--+ |+--------------+| | | | 839 |/ | | | ++-+ +-++ +--+ | 840 +-------------+/ | +--+ || | | || | 841 | /| | ++-+ +-++ | 842 | +--*|| +-------------+| |+----------------+ 843 | | ||| | +--+ | 844 | +--+|| | | | | 845 | +--+ || | +--+ | 846 | | | || | | 847 | +--+ || | | 848 | || | +--+ | 849 |+--+ || | | | | 850 || | || | +--+ | 851 |+--+ || | | 852 | || | +--+ | 853 | +--+ || +------------+ | | | |+----------------+ 854 | | | || |Area 3 +-++ +--+ +-++ Area 5 | 855 | +--+ || | | || | || | 856 | || | +-++ +-++ | 857 | +--+|| | +--+ | | Area 0 || +--+ | 858 | | ||| | | | | +--------------+| | | | 859 | +--*|| | +--+ | | +--+ | 860 | \| | | | +--+ | 861 |Area 1 |\ | +--+ | | +--+ | | | 862 +-------------+|\ | | | | | | | +--+ | 863 | \| +--+ +--+ | +--+ | 864 | \ | | | | 865 | |\ +--+ | +--+ | 866 | | \ +--+ | | | | | 867 | | \| | | | +--+ | 868 | | *--+ | | | 869 | | | | | 870 | +------------+ +----------------+ 871 | 872 | 873 As 100 | AS 200 874 | 875 Figure 3: Inter-AS Path Computation 877 The domain sequence can be carried in IRO as shown below: 879 +-------+ +-------+ +-------+ +-------+ +-------+ +-------+ +-------+ 880 |IRO | |Sub | |Sub | |Sub | |Sub | |Sub | |Sub | 881 |Object | |Object | |Object | |Object | |Object | |Object | |Object | 882 |Header | |As 100 | |Area 1 | |AS 200 | |Area 3 | |Area 0 | |Area 4 | 883 | | | | | | | | | | | | | | 884 +-------+ +-------+ +-------+ +-------+ +-------+ +-------+ +-------+ 885 Combination of both AS and Area uniquely identify a domain in the domain 886 sequence. 888 Note that an Area domain identifier always belongs to the previous AS 889 that appear before it or, if no AS sub-objects are present, it is 890 assumed to be the current AS. 892 If the area information cannot be provided, PCE MAY forward the path 893 computation request to the next PCE based on AS only. If multiple 894 PCEs of different area domain exist, PCE MAY apply local policy to 895 select the next PCE. Furthermore the domain sequence (list of areas 896 within AS) in the next PCE MAYBE pre-administered or MAYBE discovered 897 via some mechanism (ex. HPCE). 899 3.4.3. Boundary Node and Inter-AS-Link 901 A PCC or PCE MAY add additional constraints covering which Boundary 902 Nodes (ABR or ASBR) or Border links (Inter-AS-link) MUST be traversed 903 while defining a domain sequence. In which case the Boundary Node or 904 Link MAY be encoded as a part of the domain-sequence using the 905 existing sub-objects. 907 Boundary Node (ABR / ASBR) can be encoded using the IPv4 or IPv6 908 prefix sub-objects. The Inter-AS link can be encoded using the IPv4 909 or IPv6 prefix or unnumbered interface sub-objects. 911 For Figure 1, an ABR to be traversed can be specified as: 913 +---------+ +---------+ +---------++---------+ +---------+ 914 |IRO | |Sub | |Sub ||Sub | |Sub | 915 |Object | |Object | |Object ||Object | |Object | 916 |Header | |Area 2 | |IPv4 ||Area 0 | |Area 4 | 917 | | | | |x.x.x.x || | | | 918 | | | | | || | | | 919 +---------+ +---------+ +---------++---------+ +---------+ 921 For Figure 2, an inter-AS-link to be traversed can be specified as: 923 +---------+ +---------+ +---------+ +---------+ +---------+ 924 |IRO | |Sub | |Sub | |Sub | |Sub | 925 |Object | |Object As| |Object | |Object | |Object As| 926 |Header | |100 | |IPv4 | |IPv4 | |200 | 927 | | | | |x.x.x.x | |x.x.x.x | | | 928 | | | | | | | | | | 929 +---------+ +---------+ +---------+ +---------+ +---------+ 931 3.4.4. PCE serving multiple domains 933 A single PCE MAYBE responsible for multiple domains; for example PCE 934 function deployed on an ABR. Domain sequence should have no impact 935 on this. PCE which can support 2 adjacent domains can internally 936 handle this situation without any impact on the neighboring domains. 938 3.4.5. P2MP 940 In case of inter-domain P2MP path computation, (Refer 941 [PCE-P2MP-PROCEDURES]) the path domain tree is nothing but a series 942 of Domain Sequences, as shown in the below figure: 944 D1-D3-D6, D1-D3-D5 and D1-D2-D4. 945 D1 946 / \ 947 D2 D3 948 / / \ 949 D4 D5 D6 951 All rules of processing as applied to P2P can be applied to P2MP as 952 well. 954 In case of P2MP, different destinations MAY have different domain 955 sequence within the domain tree, it requires domain-sequence to be 956 attached per destination. (Refer [PCE-P2MP-PER-DEST]) 958 3.4.6. HPCE 960 As per [PCE-HIERARCHY-FWK], consider a case as shown in Figure 4 961 consisting of multiple child PCEs and a parent PCE. 963 +--------+ 964 | Parent | 965 | PCE | 966 +--------+ 968 +-------------------+ +-------------------+ 969 | +--+ | | +--+ | 970 | +--+ | | | | | | | 971 | | | +--+ | | +--+ +--+ | 972 | +--* + + | | | 973 | | | +--+ | 974 | *--+ + + | 975 | | | | | +--+ | 976 | +--+ | | | | | 977 | |+--------------------------+| +--+ | 978 | ++++ +-++ | 979 | |||| +--+ | || | 980 | Area 2 ++++ | | +-++ Area 4 | 981 +-------------------+| +--+ |+-------------------+ 982 | +--+ | 983 | +--+ | | | 984 | | | +--+ | 985 | +--+ | 986 | | 987 | +--+ | 988 | | | | 989 | +--+ | 990 +------------------+| |+--------------------+ 991 | ++-+ +-++ | 992 | || | | || | 993 | ++-+ Area 0 +-++ | 994 | |+--------------------------+| +--+ | 995 | +--+ | | | | | 996 | | | | | +--+ | 997 | +--+ +--+ | | | 998 | | | + + +--+ | 999 | +--+ | | | | | 1000 | + + +--+ | 1001 | +--+ | | | 1002 | | | | | +--+ | 1003 | +--+ | | | | | 1004 | | | +--+ | 1005 | Area 1 | | Area 5 | 1006 +------------------+ +--------------------+ 1008 Figure 4: Hierarchical PCE 1010 In HPCE implementation the initiator PCE - PCE(1) can request the 1011 parent PCE to determine the domain sequence and return in the path 1012 computation reply message (PCRep), using the ERO Object. The ERO can 1013 contain an ordered sequence of sub-object such as AS and Area (OSPF/ 1014 ISIS). In this case, the PCRep would carry the domain sequence 1015 result as: 1017 +---------+ +---------+ +---------+ +---------+ 1018 |ERO | |Sub | |Sub | |Sub | 1019 |Object | |Object | |Object | |Object | 1020 |Header | |Area 2 | |Area 0 | |Area 4 | 1021 | | | | | | | | 1022 | | | | | | | | 1023 +---------+ +---------+ +---------+ +---------+ 1025 +---------+ +---------+ +---------+ +---------+ +---------+ 1026 |ERO | |Sub | |Sub | |Sub | |Sub | 1027 |Object | |Object As| |Object | |Object | |Object | 1028 |Header | |100 | |Area 2 | |Area 0 | |Area 4 | 1029 | | | | | | | | | | 1030 | | | | | | | | | | 1031 +---------+ +---------+ +---------+ +---------+ +---------+ 1033 Note that, in the case of ERO objects, no new PCEP object type is 1034 required since the ordering constraint is assumed. 1036 3.4.7. Relationship to PCE Sequence 1038 [RFC5886] and [PCE-P2MP-PROCEDURES] along with Domain Sequence 1039 introduces the concept of PCE-Sequence, where a sequence of PCEs, 1040 based on the domain sequence, should be decided and attached in the 1041 PCReq at the very beginning of path computation. 1043 An alternative would be to use domain sequences, note that PCE- 1044 Sequence can be used along with domain-sequence in which case PCE- 1045 Sequence SHOULD have higher precedence in selecting the next PCE in 1046 the inter-domain path computation procedures. Note that Domain- 1047 Sequence IRO constraints should still be checked as per the rules of 1048 processing IRO. 1050 4. IANA Considerations 1052 4.1. PCEP Objects 1054 The "PCEP Parameters" registry contains a subregistry "PCEP Objects". 1055 IANA is requested to make the following allocations from this 1056 registry. 1058 Object Name Reference 1059 Class 1060 10 IRO [RFC5440] 1061 Object-Type 1062 (TBA): Domain Sequence [This I.D.] 1064 4.2. New Sub-Objects 1066 The "PCEP Parameters" registry contains a subregistry "PCEP Objects" 1067 with an entry for the Include Route Object (IRO) and Exclude Route 1068 Object (XRO). IANA is requested to add further subobjects as 1069 follows: 1071 Subobject Type Reference 1072 TBA 4 octet AS number [This I.D.] 1073 TBA OSPF Area ID [This I.D.] 1074 TBA IS-IS Area ID [This I.D.] 1076 4.3. Error Object Field Values 1078 The "PCEP Parameters" registry contains a subregistry "Error Types 1079 and Values". IANA is requested to make the following allocations 1080 from this subregistry 1082 ERROR Meaning Reference 1083 Type 1084 TBA "Unrecognized subobject" [This I.D.] 1085 Error-Value: type code 1087 5. Security Considerations 1089 This document specifies a standard representation of domain sequence, 1090 which MAYBE used in inter-domain PCE scenarios as explained in other 1091 RFC and drafts. The new sub-objects and domain sequence mechanisms 1092 defined in this document allow finer and more specific control of the 1093 path computed by a cooperating PCE(s). Such control increases the 1094 risk if a PCEP message is intercepted, modified, or spoofed because 1095 it allows the attacker to exert control over the path that the PCE 1096 will compute or to make the path computation impossible. Therefore, 1097 the security techniques described in [RFC5440] are considered more 1098 important. 1100 Note, however, that the domain sequence mechanisms also provide the 1101 operator with the ability to route around vulnerable parts of the 1102 network and may be used to increase overall network security. 1104 6. Manageability Considerations 1106 6.1. Control of Function and Policy 1108 Several local policy decisions should be made at the PCE. Firstly, 1109 the exact behavior with regard to desired inclusion and exclusion of 1110 domains must be available for examination by an operator and may be 1111 configurable. Second, the behavior on receipt of an unrecognized 1112 sub-objects with the L or X-bit set should be configurable and must 1113 be available for inspection. The inspection and control of these 1114 local policy choices may be part of the PCEP MIB module. 1116 6.2. Information and Data Models 1118 A MIB module for management of the PCEP is being specified in a 1119 separate document [PCEP-MIB]. That MIB module allows examination of 1120 individual PCEP messages, in particular requests, responses and 1121 errors. The MIB module MUST be extended to include the ability to 1122 view the domain-sequence extensions defined in this document. 1124 6.3. Liveness Detection and Monitoring 1126 Mechanisms defined in this document do not imply any new liveness 1127 detection and monitoring requirements in addition to those already 1128 listed in [RFC5440]. 1130 6.4. Verify Correct Operations 1132 Mechanisms defined in this document do not imply any new operation 1133 verification requirements in addition to those already listed in 1134 [RFC5440]. 1136 6.5. Requirements On Other Protocols 1138 The Sub-objects defined in this document SHOULD be supported by RSVP 1139 especially for per-domain path computation [RFC5152] where the 1140 domains need to encoded in the RSVP messages. 1142 Apart from this, mechanisms defined in this document do not imply any 1143 requirements on other protocols in addition to those already listed 1144 in [RFC5440]. 1146 6.6. Impact On Network Operations 1148 Mechanisms defined in this document do not have any impact on network 1149 operations in addition to those already listed in [RFC5440]. 1151 7. Acknowledgments 1153 We would like to thank Adrian Farrel, Pradeep Shastry, Suresh Babu, 1154 Quintin Zhao, Fatai Zhang, Daniel King, Oscar Gonzalez, Chen Huaimo, 1155 Venugopal Reddy, Reeja Paul and Sandeep Boina for their useful 1156 comments and suggestions. 1158 8. References 1160 8.1. Normative References 1162 [RFC2119] Bradner, S., "Key words for use in RFCs to 1163 Indicate Requirement Levels", BCP 14, 1164 RFC 2119, March 1997. 1166 [ISO 10589] ISO, "Intermediate system to Intermediate 1167 system routeing information exchange protocol 1168 for use in conjunction with the Protocol for 1169 providing the Connectionless-mode Network 1170 Service (ISO 8473)", ISO/IEC 10589:2002. 1172 8.2. Informative References 1174 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., 1175 Srinivasan, V., and G. Swallow, "RSVP-TE: 1176 Extensions to RSVP for LSP Tunnels", RFC 3209, 1177 December 2001. 1179 [RFC3473] Berger, L., "Generalized Multi-Protocol Label 1180 Switching (GMPLS) Signaling Resource 1181 ReserVation Protocol-Traffic Engineering 1182 (RSVP-TE) Extensions", RFC 3473, January 2003. 1184 [RFC3477] Kompella, K. and Y. Rekhter, "Signalling 1185 Unnumbered Links in Resource ReSerVation 1186 Protocol - Traffic Engineering (RSVP-TE)", 1187 RFC 3477, January 2003. 1189 [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path 1190 Computation Element (PCE)-Based Architecture", 1191 RFC 4655, August 2006. 1193 [RFC4726] Farrel, A., Vasseur, J., and A. Ayyangar, "A 1194 Framework for Inter-Domain Multiprotocol Label 1195 Switching Traffic Engineering", RFC 4726, 1196 November 2006. 1198 [RFC4873] Berger, L., Bryskin, I., Papadimitriou, D., 1199 and A. Farrel, "GMPLS Segment Recovery", 1200 RFC 4873, May 2007. 1202 [RFC4874] Lee, CY., Farrel, A., and S. De Cnodder, 1203 "Exclude Routes - Extension to Resource 1204 ReserVation Protocol-Traffic Engineering 1205 (RSVP-TE)", RFC 4874, April 2007. 1207 [RFC4893] Vohra, Q. and E. Chen, "BGP Support for Four- 1208 octet AS Number Space", RFC 4893, May 2007. 1210 [RFC5152] Vasseur, JP., Ayyangar, A., and R. Zhang, "A 1211 Per-Domain Path Computation Method for 1212 Establishing Inter-Domain Traffic Engineering 1213 (TE) Label Switched Paths (LSPs)", RFC 5152, 1214 February 2008. 1216 [RFC5440] Vasseur, JP. and JL. Le Roux, "Path 1217 Computation Element (PCE) Communication 1218 Protocol (PCEP)", RFC 5440, March 2009. 1220 [RFC5441] Vasseur, JP., Zhang, R., Bitar, N., and JL. Le 1221 Roux, "A Backward-Recursive PCE-Based 1222 Computation (BRPC) Procedure to Compute 1223 Shortest Constrained Inter-Domain Traffic 1224 Engineering Label Switched Paths", RFC 5441, 1225 April 2009. 1227 [RFC5520] Bradford, R., Vasseur, JP., and A. Farrel, 1228 "Preserving Topology Confidentiality in Inter- 1229 Domain Path Computation Using a Path-Key-Based 1230 Mechanism", RFC 5520, April 2009. 1232 [RFC5521] Oki, E., Takeda, T., and A. Farrel, 1233 "Extensions to the Path Computation Element 1234 Communication Protocol (PCEP) for Route 1235 Exclusions", RFC 5521, April 2009. 1237 [RFC5886] Vasseur, JP., Le Roux, JL., and Y. Ikejiri, "A 1238 Set of Monitoring Tools for Path Computation 1239 Element (PCE)-Based Architecture", RFC 5886, 1240 June 2010. 1242 [PCE-P2MP-PROCEDURES] Zhao, Q., Dhody, D., Ali, Z., Saad,, T., 1243 Sivabalan,, S., and R. Casellas, "PCE-based 1244 Computation Procedure To Compute Shortest 1245 Constrained P2MP Inter-domain Traffic 1246 Engineering Label Switched Paths (draft-ietf- 1247 pce-pcep-inter-domain-p2mp-procedures-02)", 1248 February 2012. 1250 [PCE-HIERARCHY-FWK] King, D. and A. Farrel, "The Application of 1251 the Path Computation Element Architecture to 1252 the Determination of a Sequence of Domains in 1253 MPLS and GMPLS. 1254 (draft-ietf-pce-hierarchy-fwk-04)", June 2012. 1256 [PCEP-MIB] Kiran Koushik, A S., Stephan, E., Zhao, Q., 1257 and D. King, "PCE communication protocol(PCEP) 1258 Management Information Base", July 2010. 1260 [PCE-P2MP-PER-DEST] Dhody, D. and U. Palle, "Supporting explicit- 1261 path per destination in Path Computation 1262 Element Communication Protocol (PCEP) P2MP 1263 Path Request Message. (draft-dhody-pce-pcep- 1264 p2mp-per-destination-01)", Feb 2012. 1266 Authors' Addresses 1268 Dhruv Dhody 1269 Huawei Technologies India Pvt Ltd 1270 Leela Palace 1271 Bangalore, Karnataka 560008 1272 INDIA 1274 EMail: dhruv.dhody@huawei.com 1276 Udayasree Palle 1277 Huawei Technologies India Pvt Ltd 1278 Leela Palace 1279 Bangalore, Karnataka 560008 1280 INDIA 1282 EMail: udayasree.palle@huawei.com 1283 Ramon Casellas 1284 CTTC - Centre Tecnologic de Telecomunicacions de Catalunya 1285 Av. Carl Friedrich Gauss n7 1286 Castelldefels, Barcelona 08860 1287 SPAIN 1289 EMail: ramon.casellas@cttc.es