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Checking references for intended status: Experimental ---------------------------------------------------------------------------- ** Obsolete normative reference: RFC 6006 (Obsoleted by RFC 8306) Summary: 1 error (**), 0 flaws (~~), 1 warning (==), 1 comment (--). 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 V. Kondreddy 5 Expires: April 2, 2015 Huawei Technologies 6 September 29, 2014 8 Supporting Explicit Inclusion or Exclusion of Abstract Nodes for a 9 Subset of P2MP Destinations in Path Computation Element Communication 10 Protocol (PCEP). 11 draft-dhody-pce-pcep-p2mp-per-destination-07 13 Abstract 15 The ability to determine paths of point-to-multipoint (P2MP) 16 Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS) 17 Traffic Engineering Label Switched Paths (TE LSPs) is one the key 18 requirements for Path Computation Element (PCE). The RFC 6006 and 19 RFC 7334 describes these mechanisms for intra and inter domain path 20 computation via PCE(s). 22 This document describes the motivation and PCEP extension for 23 explicitly specifying abstract nodes for inclusion or exclusion for a 24 subset of destinations during P2MP path computation via PCE(s). 26 Status of This Memo 28 This Internet-Draft is submitted in full conformance with the 29 provisions of BCP 78 and BCP 79. 31 Internet-Drafts are working documents of the Internet Engineering 32 Task Force (IETF). Note that other groups may also distribute 33 working documents as Internet-Drafts. The list of current Internet- 34 Drafts is at http://datatracker.ietf.org/drafts/current/. 36 Internet-Drafts are draft documents valid for a maximum of six months 37 and may be updated, replaced, or obsoleted by other documents at any 38 time. It is inappropriate to use Internet-Drafts as reference 39 material or to cite them other than as "work in progress." 41 This Internet-Draft will expire on April 2, 2015. 43 Copyright Notice 45 Copyright (c) 2014 IETF Trust and the persons identified as the 46 document authors. All rights reserved. 48 This document is subject to BCP 78 and the IETF Trust's Legal 49 Provisions Relating to IETF Documents 50 (http://trustee.ietf.org/license-info) in effect on the date of 51 publication of this document. Please review these documents 52 carefully, as they describe your rights and restrictions with respect 53 to this document. Code Components extracted from this document must 54 include Simplified BSD License text as described in Section 4.e of 55 the Trust Legal Provisions and are provided without warranty as 56 described in the Simplified BSD License. 58 Table of Contents 60 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 61 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 62 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 63 3. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 4 64 3.1. Domain Sequence Tree in Inter Domain P2MP Path 65 Computation . . . . . . . . . . . . . . . . . . . . . . . 4 66 3.1.1. PCE-sequence . . . . . . . . . . . . . . . . . . . . 5 67 3.2. Explicit inclusion or exclusion of abstract nodes . . . . 5 68 4. Detailed Description . . . . . . . . . . . . . . . . . . . . 6 69 4.1. Objective . . . . . . . . . . . . . . . . . . . . . . . . 6 70 4.2. Request Message Format . . . . . . . . . . . . . . . . . 6 71 4.3. Backward Compatibility . . . . . . . . . . . . . . . . . 7 72 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 73 6. Security Considerations . . . . . . . . . . . . . . . . . . . 8 74 7. Manageability Considerations . . . . . . . . . . . . . . . . 8 75 7.1. Control of Function and Policy . . . . . . . . . . . . . 8 76 7.2. Information and Data Models . . . . . . . . . . . . . . . 8 77 7.3. Liveness Detection and Monitoring . . . . . . . . . . . . 8 78 7.4. Verify Correct Operations . . . . . . . . . . . . . . . . 8 79 7.5. Requirements On Other Protocols . . . . . . . . . . . . . 9 80 7.6. Impact On Network Operations . . . . . . . . . . . . . . 9 81 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9 82 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 83 9.1. Normative References . . . . . . . . . . . . . . . . . . 9 84 9.2. Informative References . . . . . . . . . . . . . . . . . 9 86 1. Introduction 88 The PCE architecture is defined in [RFC4655]. [RFC5862] lay out the 89 requirements for PCEP to support P2MP path computation. [RFC6006] 90 describe an extension to PCEP to compute optimal constrained intra- 91 domain (G)MPLS P2MP TE LSPs. [RFC7334] describes the mechanism for 92 inter-domain P2MP path computation. 94 Further [RFC6006] describes mechanism to specify a list of nodes that 95 can be used as branch nodes or a list of nodes that cannot be used as 96 branch nodes via Branch Node Capability (BNC) object. The BNC object 97 is used to specify which nodes have the capability to act as a branch 98 nodes or which nodes lack the capabilty. It supports IPv4 and IPv6 99 prefix sub-objects only. 101 This document explains the need to add the capability to explicitly 102 specify any abstract nodes (not just nodes with branch node 103 capabiltiy) for inclusion or exclusion for a subset of destinations. 105 [RFC7334] describes the core-tree procedure to compute inter-domain 106 P2MP tree. It assumes that, due to deployment and commercial 107 limitations, the sequence of domains for a path (the path domain 108 tree) will be known in advance. For a group of destination which 109 belong to a particular destination domain, the domain-sequence needs 110 to be encoded separately as described in [DOMAIN-SEQ]. The 111 mechanism, as described in this document, of explicitly specifying 112 abstract nodes for inclusion or exclusion for a subset of 113 destinations can be used for this purpose, where abstract nodes are 114 domains. 116 1.1. Requirements Language 118 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 119 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 120 document are to be interpreted as described in [RFC2119]. 122 2. Terminology 124 The following terminology is used in this document. 126 IRO: Include Route Object. 128 PCC: Path Computation Client: any client application requesting a 129 path computation to be performed by a Path Computation Element. 131 PCE: Path Computation Element. An entity (component, application, 132 or network node) that is capable of computing a network path or 133 route based on a network graph and applying computational 134 constraints. 136 PCEP: Path Computation Element Protocol. 138 P2MP: Point-to-Multipoint 140 P2P: Point-to-Point 142 RRO: Record Route Object 143 RSVP: Resource Reservation Protocol 145 TE LSP: Traffic Engineering Label Switched Path. 147 XRO: Exclude Route Object. 149 3. Motivation 151 3.1. Domain Sequence Tree in Inter Domain P2MP Path Computation 153 [RFC7334] describes the core-tree procedure for inter-domain path 154 computation. The procedure assumes that the sequence of domains for 155 a path (the path domain tree) will be known in advance due to 156 deployment and commercial limitations (e.g., inter-AS peering 157 agreements). 159 In the Figure 1 below, D1 is the root domain; D5 and D6 are the 160 destination domains. The ingress is A in domain D1; egresses are X, 161 Y in Domain D6 and Z in Domain D5. 163 ----------- ---------- 164 | Domain D3 | | Domain D6| 165 | | |*** *** | 166 /| | |*X* *Y* | 167 / | | |*** *** | 168 / -----------\ /---------- 169 / \ / 170 / \ / 171 / \ / 172 ------------/ \------------/ 173 | Domain D1 | | Domain D4 | 174 | *** | | | 175 | *A* | | | 176 | *** | | | 177 ------------\ /------------\ 178 \ / \ 179 \ / \ 180 \ / \ 181 \ -----------/ \---------- 182 \ | Domain D2 | | Domain D5| 183 \| | |*** | 184 | | |*Z* | 185 | | |*** | 186 ----------- ---------- 188 Figure 1: Domain Topology Example 190 In the Figure 2 below, the P2MP tree spans 5 domains. Destination in 191 D6 (X and Y) would use the domain-sequence: D1-D3-D4-D6; and 192 destination in D5 (Z) would use the domain-sequence: D1-D3-D4-D5. 194 D3 D6 195 / \ / 196 D1 D4 197 \ 198 D5 200 Figure 2: Domain Sequence Tree 202 Since destinations in different destination domain will have 203 different domain sequence within the domain tree, it requires 204 following encoding- 206 o Destination X and Y: D1-D3-D4-D6 208 o Destination Z : D1-D3-D4-D5 210 An extension in P2MP Path Computation request is needed to support 211 this. (Refer Section 4.2) 213 The abstract nodes MAY include (but not limited to) domain subobjects 214 AS number and IGP Area as described in [DOMAIN-SEQ]. 216 3.1.1. PCE-sequence 218 [RFC7334] also mentions PCE-sequence (i.e. list of PCE for each 219 domain in the path domain tree). [RFC5886] specify PCE-ID object 220 (used to specify a PCE's IP address) and (list of PCE or 221 PCE-sequence). Like domain-sequence as explained above, PCE-sequence 222 will be different for different destinations and thus should be 223 encoded per subset of destinations. 225 3.2. Explicit inclusion or exclusion of abstract nodes 227 [RFC6006] describes four possible types of leaves in a P2MP request 228 encoded in P2MP END-POINTS object. 230 o New leaves to add 232 o Old leaves to remove 234 o Old leaves whose path can be modified/reoptimized 236 o Old leaves whose path must be left unchanged 238 [RFC6006] only allows to encode a list of nodes that have (or have 239 not) the branch node capability by using the Branch Node Capability 240 (BNC) Object. This object apply to all destinations (old and new) in 241 the P2MP tree. 243 For an existing P2MP tree with an overloaded branch node, when adding 244 a set of new leaves, administrator may want to exclude that 245 particular branch node to balance the final P2MP tree. This cannot 246 be achieved via the BNC object but by explicitly excluding a 247 particular node or including a different node, for the P2MP END- 248 POINTS object for new leaves only. 250 Administrator at the Ingress can exert stronger control by providing 251 explicit inclusion or exclusion of any abstract nodes (not limited to 252 specifying nodes with branch node capability) for a group (subset) of 253 destinations and not all destinations. 255 4. Detailed Description 257 4.1. Objective 259 [RFC6006] defines Request Message Format and Objects, along with 260 . This section introduce the use of , and which are added to the . 264 To allow abstract nodes to be explicitly included or excluded for a 265 subset of destinations (encoded in one object), changes 266 are made as shown below. 268 The abstract node (encoded as subobject in and ) MAY be an 269 absolute hop, IP-Prefix, AS or IGP Area. The subobjects are 270 described in [RFC3209], [RFC3477], [RFC4874] and [DOMAIN-SEQ]. 272 Note that one P2MP Path request can have multiple 273 objects and each P2MP object may have multiple 274 destinations, the , and is applied for all 275 destinations in one such P2MP object. 277 4.2. Request Message Format 279 The format of PCReq message is modified as follows: 281 ::= 282 283 where: 284 ::= 285 286 [] 287 [] 288 [] 289 [] 290 [] 291 [] 293 where: 294 ::= 295 296 [] 297 [] 298 [] 299 [][] 300 [] 302 ::=[] 304 ::=[][] 306 ::=[] 308 From [RFC6006] usage of is changed to in this document. 311 [RFC6006] describes Branch Node Capability (BNC) Object which is 312 different from the use of and to specify inclusion/ 313 exclusion of abstract nodes for a subset of destinations as described 314 here. 316 can be used to specify the Pce-sequence instead of domain- 317 sequence. 319 4.3. Backward Compatibility 321 A legacy implementation that does not support explicit inclusion or 322 exclusion of abstract nodes for a subset of P2MP destinations will 323 act according to the procedures set out in [RFC5440], that is it will 324 find the P2MP Path Request message out of order with respect to the 325 format specified in [RFC6006]. 327 5. IANA Considerations 329 There are no new IANA allocation in this document. 331 6. Security Considerations 333 PCEP security mechanisms as described in [RFC5440], [RFC6006] and 334 [RFC7334] are applicable for this document. 336 The new explicit inclusion or exclusion of abstract nodes for a 337 subset of P2MP destination defined in this document allow finer and 338 more specific control of the path computed by a PCE. Such control 339 increases the risk if a PCEP message is intercepted, modified, or 340 spoofed because it allows the attacker to exert control over the path 341 that the PCE will compute or to make the path computation impossible. 342 Therefore, the security techniques described in [RFC5440], [RFC6006] 343 and [RFC7334] are considered more important. 345 Note, however, that the route exclusion mechanisms also provide the 346 operator with the ability to route around vulnerable parts of the 347 network and may be used to increase overall network security. 349 7. Manageability Considerations 351 7.1. Control of Function and Policy 353 Mechanisms defined in this document do not add any new control 354 function/policy requirements in addition to those already listed in 355 [RFC6006]. 357 7.2. Information and Data Models 359 Mechanisms defined in this document do not imply any new MIB 360 requirements. 362 7.3. Liveness Detection and Monitoring 364 Mechanisms defined in this document do not imply any new liveness 365 detection and monitoring requirements in addition to those already 366 listed in [RFC6006]. 368 7.4. Verify Correct Operations 370 Mechanisms defined in this document do not imply any new operation 371 verification requirements in addition to those already listed in 372 [RFC6006]. 374 7.5. Requirements On Other Protocols 376 Mechanisms defined in this document do not imply any requirements on 377 other protocols in addition to those already listed in [RFC6006]. 379 7.6. Impact On Network Operations 381 Mechanisms defined in this document do not have any impact on network 382 operations in addition to those already listed in [RFC6006]. 384 8. Acknowledgments 386 We would like to thank Pradeep Shastry, Suresh babu, Quintin Zhao, 387 Daniel King and Chen Huaimo for their useful comments and 388 suggestions. 390 9. References 392 9.1. Normative References 394 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 395 Requirement Levels", BCP 14, RFC 2119, March 1997. 397 [RFC5440] Vasseur, JP. and JL. Le Roux, "Path Computation Element 398 (PCE) Communication Protocol (PCEP)", RFC 5440, March 399 2009. 401 [RFC6006] Zhao, Q., King, D., Verhaeghe, F., Takeda, T., Ali, Z., 402 and J. Meuric, "Extensions to the Path Computation Element 403 Communication Protocol (PCEP) for Point-to-Multipoint 404 Traffic Engineering Label Switched Paths", RFC 6006, 405 September 2010. 407 9.2. Informative References 409 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., 410 and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP 411 Tunnels", RFC 3209, December 2001. 413 [RFC3477] Kompella, K. and Y. Rekhter, "Signalling Unnumbered Links 414 in Resource ReSerVation Protocol - Traffic Engineering 415 (RSVP-TE)", RFC 3477, January 2003. 417 [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation 418 Element (PCE)-Based Architecture", RFC 4655, August 2006. 420 [RFC4874] Lee, CY., Farrel, A., and S. De Cnodder, "Exclude Routes - 421 Extension to Resource ReserVation Protocol-Traffic 422 Engineering (RSVP-TE)", RFC 4874, April 2007. 424 [RFC5862] Yasukawa, S. and A. Farrel, "Path Computation Clients 425 (PCC) - Path Computation Element (PCE) Requirements for 426 Point-to-Multipoint MPLS-TE", RFC 5862, June 2010. 428 [RFC5886] Vasseur, JP., Le Roux, JL., and Y. Ikejiri, "A Set of 429 Monitoring Tools for Path Computation Element (PCE)-Based 430 Architecture", RFC 5886, June 2010. 432 [RFC7334] Zhao, Q., Dhody, D., King, D., Ali, Z., and R. Casellas, 433 "PCE-Based Computation Procedure to Compute Shortest 434 Constrained Point-to-Multipoint (P2MP) Inter-Domain 435 Traffic Engineering Label Switched Paths", RFC 7334, 436 August 2014. 438 [DOMAIN-SEQ] 439 Dhody, D., Palle, U., and R. Casellas, "Standard 440 Representation Of Domain Sequence (draft-ietf-pce-pcep- 441 domain-sequence)", July 2014. 443 Authors' Addresses 445 Dhruv Dhody 446 Huawei Technologies 447 Leela Palace 448 Bangalore, Karnataka 560008 449 INDIA 451 EMail: dhruv.ietf@gmail.com 453 Udayasree Palle 454 Huawei Technologies 455 Leela Palace 456 Bangalore, Karnataka 560008 457 INDIA 459 EMail: udayasree.palle@huawei.com 460 Venugopal Reddy Kondreddy 461 Huawei Technologies 462 Leela Palace 463 Bangalore, Karnataka 560008 464 INDIA 466 EMail: venugopalreddyk@huawei.com