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Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the RFC 3978 Section 5.4 Copyright Line does not match the current year -- The exact meaning of the all-uppercase expression 'MAY NOT' is not defined in RFC 2119. If it is intended as a requirements expression, it should be rewritten using one of the combinations defined in RFC 2119; otherwise it should not be all-uppercase. == The expression 'MAY NOT', while looking like RFC 2119 requirements text, is not defined in RFC 2119, and should not be used. Consider using 'MUST NOT' instead (if that is what you mean). Found 'MAY NOT' in this paragraph: The proposed solution SHOULD be able to interoperate with fault detection mechanisms of intra-AS TE and MAY or MAY NOT require the inter-AS TE tunnel ending addresses to be known or routable across IGP areas (OSPF) or levels(IS-IS) within the transiting ASes with working return paths. == 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 'SHOULD not' in this paragraph: The proposed solution (s) SHOULD not introduce unnecessary complexity to the current operating network to such a degree that it would affect the stability and diminish the benefits of deploying such solution over SP networks. == 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 'SHOULD not' in this paragraph: The deployment of inter-AS MPLS TE SHOULD not have impact on existing BGP-based traffic engineering or MPLS TE mechanisms to allow for a smooth migration or co-existence. -- The document seems to lack a disclaimer for pre-RFC5378 work, but may have content which was first submitted before 10 November 2008. If you have contacted all the original authors and they are all willing to grant the BCP78 rights to the IETF Trust, then this is fine, and you can ignore this comment. If not, you may need to add the pre-RFC5378 disclaimer. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (October 2003) is 7498 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) == Unused Reference: 'ISIS-TE' is defined on line 1172, but no explicit reference was found in the text == Unused Reference: 'OSPF-TE' is defined on line 1175, but no explicit reference was found in the text == Unused Reference: 'BGP-Label' is defined on line 1194, but no explicit reference was found in the text == Unused Reference: 'INTER-AS-TE' is defined on line 1197, but no explicit reference was found in the text == Unused Reference: 'TE-SURVIV' is defined on line 1233, but no explicit reference was found in the text ** Downref: Normative reference to an Informational RFC: RFC 2702 (ref. 'TE-REQ') ** Obsolete normative reference: RFC 1771 (ref. 'BGP') (Obsoleted by RFC 4271) -- Possible downref: Non-RFC (?) normative reference: ref. 'LSPPING' ** Downref: Normative reference to an Informational RFC: RFC 3564 (ref. 'DS-TE') -- No information found for draft-ietf-tewg-diff - is the name correct? -- Possible downref: Normative reference to a draft: ref. 'DSTE-PROT' == Outdated reference: A later version (-07) exists of draft-ietf-mpls-rsvp-lsp-fastreroute-03 ** Downref: Normative reference to an Informational draft: draft-ietf-isis-traffic (ref. 'ISIS-TE') == Outdated reference: A later version (-13) exists of draft-ietf-ospf-ospfv3-traffic-01 == Outdated reference: A later version (-05) exists of draft-vasseur-mpls-computation-rsvp-03 -- Possible downref: Normative reference to a draft: ref. 'PATH-COMP' -- Possible downref: Normative reference to a draft: ref. 'OSPF-TE-CAP' ** Downref: Normative reference to an Informational RFC: RFC 3469 (ref. 'MPLS-Recov') ** Obsolete normative reference: RFC 3107 (ref. 'BGP-Label') (Obsoleted by RFC 8277) -- Possible downref: Normative reference to a draft: ref. 'INTER-AS-TE' -- Possible downref: Non-RFC (?) normative reference: ref. 'EXCLUDE-ROUTE' -- No information found for draft-ietf-l3vpn - is the name correct? -- Obsolete informational reference (is this intentional?): RFC 3272 (ref. 'TE-OVW') (Obsoleted by RFC 9522) Summary: 10 errors (**), 0 flaws (~~), 14 warnings (==), 12 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 IETF Internet Draft Raymond Zhang, Editor 2 Internet Engineering Task Force Infonet Services Corporation 3 Document: JP Vasseur, Co-Editor 4 draft-ietf-tewg-interas-mpls-te-req-01.txt CISCO Systems, Inc 5 October 2003 6 Expires: April 2004 8 MPLS Inter-AS Traffic Engineering requirements 9 draft-ietf-tewg-interas-mpls-te-req-01.txt 11 Status of this Memo 13 This document is an Internet-Draft and is in full conformance with 14 all provisions of Section 10 of RFC2026. Internet-Drafts are Working 15 documents of the Internet Engineering Task Force (IETF), its areas, 16 and its working groups. Note that other groups may also distribute 17 working documents as Internet-Drafts. 19 Internet-Drafts are draft documents valid for a maximum of six 20 months and may be updated, replaced, or obsoleted by other documents 21 at any time. It is inappropriate to use Internet-Drafts as 22 reference material or to cite them other than as "work in progress." 24 The list of current Internet-Drafts can be accessed at 25 http://www.ietf.org/ietf/1id-abstracts.txt. 26 The list of Internet-Draft Shadow Directories can be accessed at 27 http://www.ietf.org/shadow.html. 29 Abstract 31 This document discusses requirements for the support of inter-AS 32 MPLS Traffic Engineering (MPLS TE). The main objective of this 33 document is to present a set of requirements which would result in a 34 set of general guidelines in the definition, selection and 35 specification development for any technical solution(s) meeting 36 these requirements. 38 Summary for Sub-IP related Internet Drafts 40 RELATED DOCUMENTS: 41 None 43 WHERE DOES IT FIT IN THE PICTURE OF THE SUB-IP WORK 44 TEWG 46 WHY IS IT TARGETED AT THIS WG(s) 47 It is stated in the charter that documenting SP requirements in this 48 area are one of the work items to be undertaken by TEWG. 50 JUSTIFICATION 51 The TEWG charter further states that "The working group may also 52 consider the problems of traffic engineering across autonomous 53 systems boundaries." 54 This draft discusses the requirements for a traffic engineering 55 mechanism across autonomous systems boundaries that would also be 56 interoperable with current intra-AS traffic engineering mechanisms. 58 Conventions used in this document 60 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 61 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in 62 this document are to be interpreted as described in RFC-2119. 64 Table of Contents 66 1. Introduction.......................................................3 67 2. Contributing Authors...............................................4 68 3. Definitions and Requirements Statement.............................5 69 3.1. Definitions......................................................5 70 3.2. Objectives and Requirements of Inter-AS Traffic Engineering......6 71 3.2.1. Inter-AS Bandwidth Guarantees..................................6 72 3.2.2. Inter-AS Resource Optimization.................................7 73 3.2.3. Fast Recovery across ASes......................................8 74 3.3. Inter-AS Traffic Engineering Requirements Statement..............8 75 4. Application Scenarios..............................................8 76 4.1. Application Scenarios Requiring Inter-AS Bandwidth Guarantees....8 77 4.1.1. Scenario I - Extended or Virtual PoP...........................9 78 4.1.2. Scenario II - Extended or Virtual Trunk.......................10 79 4.1.3. Scenario III - End-to-end Inter-AS MPLS TE From CE to CE......11 80 4.2. Application Scenarios Requiring Inter-AS Resource Optimization..12 81 4.2.1. Scenario IV - TE across multi-AS within a Single SP 82 Administrative Domain.........................................12 83 4.2.2. Scenario V - Transit ASes as Primary and Redundant Transport..13 84 5. Detailed Requirements for Inter-AS MPLS Traffic Engnineering......14 85 5.1. Requirements within one SP Administrative Domain................14 86 5.1.1. Inter-AS MPLS TE Operations and Interoperability..............14 87 5.1.2. Protocol Signaling and Path Computations......................15 88 5.1.3. Optimality....................................................15 89 5.1.4. Support of diversely routed inter-AS TE LSP...................16 90 5.1.5. Re-optimization...............................................16 91 5.1.6. Fast Recovery support using MPLS TE Fast Reroute..............16 92 5.1.7. DS-TE Support.................................................17 93 5.1.8. Hierarchical LSP Support and Forwarding Adjacency (FA)........17 94 5.1.9. Mapping of traffic onto Multiple Inter-AS MPLS TE Tunnels.....17 95 5.1.10. Inter-AS MPLS TE Management..................................17 96 5.1.10.1. Inter-AS MPLS TE MIB Requirements..........................17 97 5.1.10.2. Inter-AS MPLS TE Fault Management Requirements.............18 98 5.2. Requirements for Inter-AS MPLS TE across Multiple SP 99 Administrative Domains..........................................19 100 5.2.1. Confidentiality...............................................19 101 5.2.2. Policy Control................................................20 102 5.2.2.1. Inter-AS TE Agreement Enforcement Polices...................20 103 5.2.2.2. Inter-AS TE Rewrite Policies................................21 104 5.2.2.3 Inter-AS Traffic Policing....................................21 105 6. Evaluation Criteria...............................................21 106 6.1. Detailed Requirement Satisfactions..............................21 107 6.2. Scalability and Extensibility...................................21 108 6.3. Complexity and Risks............................................22 109 6.4. Performance.....................................................22 110 6.5. Backward Compatibility..........................................22 111 7. Security Considerations...........................................22 112 8. Acknowledgement...................................................21 113 9. Editor's Addresses................................................23 114 10. Normative References.............................................23 115 11. Informative References...........................................24 116 12. Full Copyright Statement.........................................25 117 Appendix A. Brief Description of BGP based Inter-AS Traffic 118 Engineering..............................................26 120 1. Introduction 122 The MPLS Traffic Engineering mechanism documented in [TE-RSVP] may 123 be deployed by Service Providers to achieve some of the most 124 important objectives of network traffic engineering as described in 125 [TE-OVW]. These objectives are summarized as listed below: 127 - Supporting end-to-end services requiring QoS guarantees 128 - Performing network resource optimization 129 - Providing fast recovery 131 However, this traffic engineering mechanism can only be used within 132 an Autonomous System (AS). 134 This document discusses requirements for an inter-AS MPLS Traffic 135 Engineering mechanism that may be used to achieve the same set of 136 objectives across AS boundaries within or beyond SPs'administrative 137 domains. 139 The document will also present a set of application scenarios where 140 the inter-AS traffic engineering mechanism may be required. 142 These application scenarios will also be used to further facilitate 143 the discussions for a list of detailed requirements for such an 144 inter-AS Traffic Engineering mechanism along with the evaluation 145 criteria for any technical solution(s) meeting these requirements. 147 Please note that there are other means of traffic engineering 148 including IGP metrics based (for use within an AS) and BGP attribute 149 based (for use across ASes; see Appendix A) traffic engineering 150 mechanisms. However, these means offer coarser control of traffic 151 paths, and do not readily offer bandwidth guarantees or fast 152 restoration, and therefore will not be discussed further in this 153 document. 155 2. Contributing Authors 157 This document was the collective work of several. The text and 158 content of this document was contributed by the editors and the 159 co-authors listed below (The contact information for the editors 160 appears in section 9, and is not repeated below.): 162 Kenji Kumaki 163 KDDI Corporation 164 Garden Air Tower 165 Iidabashi, Chiyoda-ku, 166 Tokyo 102-8460, 167 JAPAN 168 E-mail : ke-kumaki@kddi.com 170 Paul Mabey 171 Qwest Communications 172 950 17th Street, 173 Denver, CO 80202 174 USA 175 Email: pmabey@qwest.com 177 Nadim Constantine 178 Infonet Services Corporation 179 2160 E. Grand Ave. 180 El Segundo, CA 90025 181 USA 182 Email: nadim_constantine@infonet.com 184 Pierre Merckx 185 EQUANT 186 1041 route des Dolines - BP 347 187 06906 SOPHIA ANTIPOLIS Cedex 188 FRANCE 189 Email: pierre.merckx@equant.com 191 Ting Wo Chung 192 Bell Canada 193 181 Bay Street, Suite 350 194 Toronto, Ontario, Canada, M5J 2T3 195 Email: ting_wo.chung@bell.ca 197 Jean-Louis Le Roux 198 France Telecom 199 2, avenue Pierre-Marzin 200 22307 Lannion Cedex 201 France 202 E-mail: jeanlouis.leroux@francetelecom.com 203 Yonghwan Kim 204 SBC Laboratories, Inc. 205 4698 Willow Road 206 Pleasanton, CA 94588 207 USA 208 Email: Yonghwan_Kim@labs.sbc.com 210 3. Definitions and Requirements Statement 212 3.1. Definitions 214 The following provides a list of abbreviations or acronyms 215 specifically pertaining to this document: 217 SP: Service Providers including regional or global providers 219 SP Administrative Domain: a single SP administration over a network 220 or networks that may consist of one AS or 221 multiple ASes. 223 IP-only networks: SP's network where IP routing protocols such as 224 IGP/ BGP are activated 226 IP/MPLS networks: SP's network where MPLS switching capabilities and 227 signaling controls (e.g. ones described in 228 [MPLS-ARCH]) are activated in addition to IP 229 routing protocols. 231 Intra-AS TE: A generic definition for traffic engineering mechanisms 232 operating over IP-only and/ or IP/MPLS network within an 233 AS. 235 Inter-AS TE: A generic definition for traffic engineering mechanisms 236 operating over IP-only and/ or IP/MPLS network across 237 one or multiple ASes. 239 TE LSP: MPLS Traffic Engineering Label Switched Path 241 Intra-AS MPLS TE: An MPLS Traffic Engineering mechanism where its 242 TE LSPs Head-end LSR and Tail-end LSR reside in 243 the same AS for traffic engineering purposes. 245 Inter-AS MPLS TE: An MPLS Traffic Engineering mechanism where its 246 TE LSPs Head-end LSR and Tail-end LSR do not 247 reside within the same AS or both Head-end LSR and 248 Tail-end LSR are in the same AS but the TE LSP 249 transiting path may be across different ASes 251 ASBR Routers: Border routers used to connect to another AS of a 252 different or the same Service Provider via one or more 253 links inter-connecting between ASes. 255 Inter-AS TE Path: An TE path traversing multiple ASes and ASBRs, 256 e.g. AS1-ASBR1-inter-AS link(s)-ASBR2-AS2... 257 ASBRn-ASn. 259 Inter-AS TE Segment: A portion of the Inter-AS TE path. 261 PCS: Path Computation Server (e.g. an LSR or an off-line tool) 263 PCC: Path Computation Client (e.g. an LSR) 265 CE: Customer Edge Equipment 267 PE: Provider Edge Equipment that has direct connections to CEs. 269 P: Provider Equipment that has backbone trunk connections only. 271 VRF: Virtual Private Network (VPN) Routing and Forwarding Instance. 273 PoP: Point of presence or a node in SP's network. 275 SRLG: A set of links may constitute a 'shared risk link group' 276 (SRLG) if they share a resource whose failure may affect all 277 links in the set as defined in [GMPLS-ROUT]. 279 Please note that the terms of CE, PE and P used throughout this 280 document are generic in their definitions. In particular, whenever 281 such acronyms are used, it does not necessarily mean that CE is 282 connected to a PE in a VRF environment described in such IETF drafts 283 as [BGP-MPLSVPN]. 285 3.2. Objectives and Requirements of Inter-AS Traffic Engineering 287 As mentioned in section 1 above, some SPs have requirements for 288 achieving the same set of traffic engineering objectives as 289 presented in [TE-OVW] across AS boundaries. 291 This section examines these requirements in each of the key 292 corresponding areas: 1) Inter-AS bandwidth guarantees; 2) 293 Inter-AS Resource Optimization and 3) Fast Recovery across ASes, 294 i.e. Recovery of Inter-AS Links/SRLG and ASBR Nodes. 296 3.2.1. Inter-AS Bandwidth Guarantees 298 The DiffServ IETF working group has defined a set of mechanisms 299 described in [DIFF_ARCH], [DIFF_AF] and [DIFF_EF] or [MPLS-Diff] 300 that can be activated at the edge or over a DiffServ domain to 301 contribute to the enforcement of a (set of) QoS policy(ies), which 302 can be expressed in terms of maximum one-way transit delay, 303 inter-packet delay variation, loss rate, etc. 305 Many SPs have some or full deployment of Diffserv implementations in 306 their networks today, either across the entire network or at the 307 least, on the edge of the network across CE-PE links. 309 In situations where strict QOS bounds are required, admission 310 control inside the backbone of a network is in some cases required 311 in addition to current Diffserv mechanisms. 313 When the propagation delay can be bounded, the performance targets, 314 such as maximum one-way transit delay may be guaranteed by providing 315 bandwidth guarantees along the Diffserv-enabled path. 317 One typical example of this requirement is to provide bandwidth 318 guarantees over an end-to-end path for VoIP traffic classified as EF 319 (Expedited Forwarding [DIFF_EF]) class in a Diffserv-enabled 320 network. When the EF path is extended across multiple ASes, 321 inter-AS bandwidth guarantee is then required. 323 Another case for inter-AS bandwidth guarantee is the requirement for 324 guaranteeing a certain amount of transit bandwidth across one or 325 multiple ASes. 327 Several application scenarios are presented to further illustrate 328 this requirement in section 4 below. 330 3.2.2. Inter-AS Resource Optimization 332 In Service Provider (SP) networks, the BGP protocol [BGP] is 333 deployed to exchange routing information between ASes. The inter-AS 334 capabilities of BGP may also be employed for traffic engineering 335 purposes across the AS boundaries. Appendix A provides a 336 brief description of the current BGP-based inter-AS traffic 337 engineering practices. 339 SPs have managed to survive with this coarse set of BGP-based 340 traffic engineering facilities across inter-AS links in a largely 341 best effort environment. Certainly in many cases ample bandwidth 342 within SP's network and across inter-AS links reduces the need for 343 more elaborated inter-AS TE policies. 345 However, in the case where a SP network is deployed over multiple 346 ASes, for example, as the number of inter-AS links grows, the 347 complexity of the inter-AS policies and the difficulty in inter-AS 348 TE path optimization increase to a level such that it may soon 349 become unmanageable. 351 Another example is where inter-AS links are established between 352 different SP administrative domains. Un-deterministic factors such 353 as un-coordinated routing and network changes as well as sub-optimum 354 traffic conditions would potentially lead to a complex set of 355 Inter-AS traffic engineering policies where current traffic 356 engineering mechanisms would probably not scale well. 358 In these situations where resource optimization is required and/ or 359 specific routing requirements arise, the BGP-based inter-AS 360 facilities will need to be complemented by a more granular inter-AS 361 traffic engineering mechanism. 363 3.2.3. Fast Recovery across ASes 365 When extending services such as VoIP across ASes, customers often 366 demands SPs to maintain the same level of performance targets such 367 as packet loss and service availability as ones that can be achieved 368 within an AS. As a consequence, fast convergence in a stable 370 fashion upon link/SRLG/node failure becomes a strong requirement, 371 clearly difficult to achieve with current inter-domain techniques, 372 especially in cases of link/SRLG failures between ASBRs or ASBR node 373 failures. 375 3.3. Inter-AS Traffic Engineering Requirements Statement 377 Just as in the applicable case of deploying MPLS TE in a SP's 378 network, an inter-AS TE method in addition to BGP-based traffic 379 engineering capabilities needs to be deployed across inter-AS links 380 over where resource optimization, QOS guarantees and fast recovery 381 are required. 383 This is especially critical in a Diffserv-enabled, multi-class 384 environment described in [PSTE] where statistical performance 385 targets must be maintained consistently over the entire path 386 across different ASes. 388 The approach of extending current intra-AS MPLS TE capabilities 389 [TE-RSVP] across inter-AS links for IP/MPLS networks is considered 390 here because of already available implementations and operational 391 experiences. 393 Please note that the inter-AS traffic engineering over an IP-only 394 network is for future consideration since there is no sufficient 395 interest for similar requirements to those of IP/MPLS networks 396 at this time. 398 4. Application Scenarios 400 The following sections present a few application scenarios over 401 IP/MPLS networks where requirements cannot be addressed with current 402 intra-AS MPLS TE mechanism and give rise to considerations for 403 inter-AS MPLS traffic engineering requirements. 405 Although not explicitly noted in the following discussions, fast 406 recovery of traffic path(s) crossing multiple ASes in a stable 407 fashion is particularly important in case of link/SRLG/node failure 408 at AS boundaries for all application scenarios presented here. 410 4.1. Application Scenarios Requiring Inter-AS Bandwidth Guarantees 411 4.1.1 Scenario I - Extended or Virtual PoP (VPoP) 413 A global service provider (SP1), for example would like to expand 414 its reach in a region where a regional service provider's (SP2) 415 network has already established an extended coverage in its PoP 416 density. 418 In this scenario, the SP1 may establish interconnections with SP2 in 419 one or multiple points in that region. It may then use SP2's 420 network as an extended transport by co-locating aggregation routers 421 in some SP2's PoPs that are in the regions where SP1 has a larger 422 number of customer sites. 424 In order to ensure bandwidth capacity provided by SP2 and achieve 425 some degrees of transparency to SP2's network changes in terms of 426 capacity and network conditions, one or more Inter-AS MPLS TE 427 trunk(s) can be built between SP1's ASBR or PE router inside AS1 and 428 SP1's PE routers co-locating in SP2's PoPs, as illustrated in the 429 diagram below: 431 <===========Inter-AS MPLS TE Tunnel===========> 432 ----- ----- 433 ________|ASBR |___Inter-AS___|ASBR |________ 434 | | RTR | Link | RTR | | 435 ---- ----- ----- ----- ----- 436 |SP1 |_____| SP2 | | SP1 | 437 |VPoP| |P/PE | |P/PE | 438 ---- ----- ----- ----- ----- 439 |________|ASBR |___Inter-AS___|ASBR |________| 440 | RTR | Link | RTR | 441 ----- ----- 442 <=================Inter-AS MPLS TE Tunnel=================> 443 +-SP1 AS1-+ +-------SP2 AS2-----+ +------SP1 AS1------+ 445 In situations where end-to-end Diffserv paths must be maintained, 446 both SP's networks may need to provision Diffserv PHB at each hop 447 supporting a set of traffic classes with compatible performance 448 targets. The subsequent issues regarding Service Level Agreement 449 (SLA) boundaries, reporting and measuring system inter-operability 450 and support demarcations are beyond the scope of this document and 451 will therefore not be discussed here. 453 Note also that either the SP1 or SP2 network may not be a 454 Diffserv-aware network. The scenario would still apply to provide 455 bandwidth guarantees. 457 The SP2, on the other hand, can similarly choose to expand its reach 458 beyond its servicing region over SP1's network via inter-AS MPLS 459 TE paths. 461 It is worth mentioning that these remote aggregation routers 462 co-located in other SP's network will unlikely participate in 463 hosting SP's IGP and BGP routing planes and will most likely 464 maintain its own AS or be part of the SP1's AS. In this case, such 465 TE tunnels may cross several ASes, but the Head-end and Tail-end 466 LSRs of TE tunnel may have the same AS number, as shown in the 467 diagram above. 469 4.1.2. Scenario II - Extended or Virtual Trunk 471 Instead of co-locating a PE router in SP2's PoP, SP1, for example 472 may also choose to aggregate customer VPN sites onto a SP2's PE 473 router where inter-AS TE tunnels can be built and signaled through 474 SP2's MPLS network between the SP2 PoP (to which SP1 customer CEs 475 are directly connected) and SP1's ASBR or PE routers inside SP2's 476 network. This allows SP1�s customers connected to SP2 PE router to 477 receive a guaranteed bandwidth service up to the TE LSP tail-end 478 router located in SP1's network. 480 In this scenario, there could be two applicable cases: 482 Case 1 - the inter-AS MPLS TE tunnel functions as an extended or 483 virtual trunk aggregating SP1 CE's local-loop access circuits on 484 SP2's MPLS network over which the bandwidth can be guaranteed to the 485 TE LSP tail-end router located in SP1�s network, as shown in the 486 diagram below: 488 <====Inter-AS MPLS TE Tunnel====> 489 or 490 < ===Inter-AS MPLS TE Tunnel===============> 492 ---- ----- ----- ----- ----- 493 | CE |_____Local___| SP2 |___|ASBR |___Inter-AS___|ASBR |___|SP1 | 494 | | Loop | PE | | RTR | Link | RTR | |PE | 495 ---- ----- ----- ----- ----- 497 +SP1 Customer AS3+ +-----SP2 AS2---+ +-SP1 AS1-------+ 499 Case 2 - the inter-AS MPLS TE tunnel in this case functions as an 500 extended or virtual local access link from SP1's CE on SP2's network 501 to the SP1's ASBR or PE: 503 <==============Inter-AS MPLS TE Tunnel==============> 504 or 505 <==============Inter-AS MPLS TE Tunnel========================> 507 ---- ----- ----- ----- ----- 508 | CE |____Local_____| SP2 |___|ASBR |___Inter-AS___|ASBR |___|SP1 | 509 | | Loop | PE | | RTR | Link | RTR | |PE | 510 ---- ----- ----- ----- ----- 512 +SP1 Customer AS3+ +------SP2 AS2---+ +--SP1 AS1-----+ 513 In case 2 above, SP2 may elect to establish an aggregating or 514 hierarchical intra-AS MPLS TE tunnel between the transiting P or PE 515 router and SP2's ASBR router just to reduce the number of tunnel 516 states signaled from the SP2 PE to where SP1's CEs are connected. 518 4.1.3. Scenario III - End-to-end Inter-AS MPLS TE From CE to CE 520 In this scenario as illustrated below, customers require to 521 establish MPLS TE tunnel from CE1 to CE2 end-to-end across several 522 SP's networks. One application example would be guaranteed 523 bandwidth for services such as voice- or video-over-IP services. 525 <======================Inter-AS MPLS TE Tunnel==================> 527 --- ----- ----- ----- ----- --- 528 |CE1|_____| SP2 |___|ASBR |__Inter-AS__|ASBR |____| SP1 |_____|CE2| 529 | | | PE | | RTR | Link | RTR | | PE | | | 530 --- ----- ----- ----- ----- --- 532 +Cust AS1+ +---SP2 AS-----+ +-------SP1 AS-------+ +Cust ASx+ 534 The diagram below illustrates another example where CE1 and CE2 are 535 customers of SP1 with eBGP peering relationships established across 536 the CE-PE links. A inter-AS MPLS TE tunnel may then be established 537 from CE1 in AS1 to CE2 which may belong to the same AS or different 538 AS than that of CE1 across SP1's network in AS2. 540 <===============Inter-AS MPLS TE Tunnel=====================> 542 --- ----- ---- ---- ----- --- 543 |CE1|______| SP1 |_____|SP1 |____|SP1 |____| SP1 |_________|CE2| 544 | | | PE1 | |P1 | |P2 | | PE2 | | | 545 --- ----- ---- ---- ----- --- 547 +-Cust AS1-+ +-------------SP1 AS2----------------+ +-Cust ASx-+ 549 The above example shows that SP1's network has a single AS. 550 Obviously, there may be multiple ASes between CE1 and CE2 as well in 551 the SP1's network. 553 In addition, where both CE1 and CE2 residing in the same AS, they 554 likely share the same private AS number. 556 Scenario III however, will not scale well should there be a larger 557 number of inter-AS TE MPLS tunnels in some degrees of partial mesh 558 or full mesh. Therefore, it is expected that this scenario will 559 not have a large number of deployments, unless some mechanisms such 560 as hierarchical intra-AS TE-LSPs are used to reduce the number of 561 signaling states 563 4.2. Application Scenarios Requiring Inter-AS Resource Optimization 565 The scenarios presented in this section mainly deal with inter-AS 566 resource optimization. 568 4.2.1. Scenario IV - TE across multi-AS within a Single SP 569 Administrative Domain 571 As mentioned in [TE-APP], SPs have generally admitted that the 572 current MPLS TE mechanism provides a great deal of tactical and 573 strategic values in areas of traffic path optimization [TE-RSVP] and 574 rapid local repair capabilities [TE-FRR] via a set of on-line or 575 off-line constraint-based searching algorithms. 577 From a service provider's perspective, another way of stating the 578 objectives of traffic engineering is to be able to deliver more 579 customer traffic with already available capacity in the network 580 without violating performance targets, and/ or to provide better QOS 581 services via an improved network utilization, operating more likely 582 below congestion thresholds. 584 It is worth noting that situations where resource provisioning is 585 not an issue, e.g. low density in inter-AS connectivity or ample 586 inter-AS capacity may not require more scalable and granular TE 587 facilities beyond BGP routing policies since such policies could be 588 rather simple and because inter-AS resource optimization is not an 589 absolute requirement. 591 However many SPs, especially those with networks across multiple 592 continents as well as sparsely connected, have designed their 593 multi-AS routing policies, for example, along or within the 594 continental or sub-continental boundaries where the number of ASes 595 can range from a very few to dozens. Generally, inter-continent or 596 sub-continent capacity is very expensive. Some Service Providers 597 have multiple ASes in the same country and would like to optimize 598 resources over their inter-region links. This would demand a 599 more scalable degree of resource optimization, which warrants the 600 consideration of extending current intra-AS MPLS TE capabilities 601 across inter-AS links. 603 In addition, one may only realize higher efficiency in conducting 604 traffic optimization and path protection/ restoration planning when 605 coordinating all network resources (not partially) as a whole. For 606 a network which may consist of many ASes, this could be realized via 607 the establishment of inter-AS TE LSPs as shown in the diagragm 608 below: 610 <===================Inter-AS MPLS Tunnel=============> 611 -------- -------- -------- 612 | |_______________| |____________| | 613 | SP1 |_______________| SP1 |____________| SP1 | 614 | AS1 |_______________| AS2 |____________| AS3 | 615 | | | | | | 616 -------- -------- -------- 617 || || 618 || --------- || 619 ||___________________| SP1 |________________|| 620 |____________________| AS4 |_________________| 621 | | 622 --------- 623 The motivation for inter-AS MPLS TE is even more prominent in a 624 Diffserv-enabled network over which statistical performance targets 625 are to be maintained from any point to any point of the network as 626 illustrated in the diagram below with an inter-AS DS-TE LSP: 628 <===================Inter-AS MPLS DS-TE Tunnel=============> 629 ---- ----- ----- ----- ----- ---- 630 | PE |__| P |___|ASBR |___Inter-AS___|ASBR |___|P |___|PE | 631 | RTR| | RTR | | RTR | Link | RTR | |RTR | |RTR | 632 ---- ----- ----- ----- ----- ---- 633 +------------SP1 AS1---------+ +------------SP1 AS2------+ 635 For example , the inter-AS MPLS DS-TE LSP shown in the diagram above 636 could be used used to transport a set of L2 Pseudo Wires or VoIP 637 traffic with corresponding QoS requirement. 639 Furthermore, fast recovery in case of ASBR-ASBR link failure or ASBR 640 node failure is a strong requirement for such services. 642 4.2.2. Scenario V - Transit ASes as Primary and Redundant Transport 644 Scenario V presents another possible deployment case. SP1 with AS1 645 wants to link a regional network to its core backbone by building an 646 inter-AS MPLS TE tunnel over one or multiple transit ASes belonging 647 to SP2, SP3, etc. as shown in the following diagram: 649 <===========Inter-AS MPLS TE Tunnel=======> 650 [ ] [ ] [ ] 651 [ ---- ---- ] [ ---- ---- ] [ ---- ---- ] 652 [ |P/PE|__|ASBR|]_Inter-AS_[|ASBR|.|ASBR|]_Inter-AS_[|ASBR| |P/PE|] 653 [ |RTR | |RTR |] Link [|RTR | |RTR |] Link [|RTR | |RTR |] 654 [ ---- ---- ] [ ---- ---- ] [ ---- ---- ] 655 [ ] [ ] [ ] 656 <================Inter-AS MPLS TE Tunnel=====================> 657 +SP1 Regional ASx+ +Transit SP2 AS2,etc...SPi ASi+ +------SP1 AS1-+ 659 This scenario can be viewed as a broader case of Scenario I shown in 660 section 4.1.1 where the "VPoP" could be expanded into a regional 661 network of SP1. By the same token, the AS number for SP1's 662 regional network ASx may be the same as or different from AS1. 664 The inter-AS MPLS TE LSP in this case may also be used to backup an 665 internal path as depicted in the diagram below, although this could 666 introduce routing complexities: 668 <===========Inter-AS MPLS TE Tunnel=======> 669 +----------------------------SP1 AS1-----------------------------+ 670 [ ] 671 [ ---- ---- ---- ---- ] 672 [ |P/PE|__|ASBR|__________Primary Intera-AS________|P | |PE |] 673 [ |RTR | |RTR | Link |RTR | |RTR |] 674 [ ---- ---- ---- ---- ] 675 [ | | ] 676 [ ---- ---- ] 677 [ |ASBR| |ASBR| ] 678 [ |RTR | |RTR | ] 679 [ ---- ---- ] 680 ^ | | ^ 681 | | | | 682 | | [ ] | | 683 | | [ ---- ---- ] | | 684 | |__ Inter-AS_[|ASBR|..|ASBR|]_Inter-AS_| | 685 | Link [|RTR | |RTR |] Link | 686 | [ ---- ---- ] | 687 | [ ] | 688 | | 689 +======Backup Inter-AS MPLS TE Tunnel======+ 690 +Transit SP2 AS2,SP3 AS3,etc....SPi ASi+ 692 5. Detailed Requirements for Inter-AS MPLS Traffic Engnineering 694 This section discusses detailed requirements for inter-AS MPLS TE in 695 two principal areas: 1) requirements for inter-AS MPLS TE in the 696 same SP administrative domain and 2) requirements for inter-AS MPLS 697 TE across different SP administrative domains. 699 5.1. Requirements within one SP Administrative Domain 701 This section presents detailed requirements for inter-AS MPLS TE 702 within the same SP administrative domain. 704 5.1.1. Inter-AS MPLS TE Operations and Interoperability 706 The inter-AS MPLS TE solution SHOULD be consistent with requirements 707 discussed in [TE-REQ] and the derived solution MUST be such that 708 it will interoperate seamlessly with current intra-AS MPLS TE 709 mechanism and inherit its capability sets from [TE-RSVP]. 711 The proposed solution MUST allow to provision at the Head/Tail end 712 with end-to-end RSVP signaling (eventually with loose paths) 713 traversing across the interconnected ASBRs, without further 714 provisioning required along the transit path. 716 5.1.2. Protocol Signaling and Path Computations 718 One can conceive that an inter-AS MPLS TE tunnel path signaled 719 across inter-AS links consists of a sequence of intra-AS segments. 721 The proposed solution SHOULD provide the ability to either 722 explicitly select or auto-discover the following elements 723 when signaling the inter-AS TE LSP path: 725 - a set of AS numbers as loop HoPs 726 - a set of ASBR LSRs 728 and to specify the above elements in the ERO and record them in the 729 RRO of the Resv message just to keep track of the set of ASes or 730 ASBRs traversed by the inter-As TE LSP. 732 For example, one may provide a manual description of all or some of 733 the hops (loose routing) the TE LSP must traverse, allowing to keep 734 the information related to the intra-AS resources confidential while 735 still leaving intra-AS routing decisions to local operators. The 736 solution may allow the Head-end LSR to compute the TE LSP 737 path up to the next entry point in the next hop AS. 739 In the case of establishing inter-AS TE LSP traversing multiple ASes 740 within the same SP networks, the solution SHOULD also allow the 741 Headend LSR to explicitly specify the hops across anyone of 742 the transiting ASes and the TE tunnel headhend SHOULD also check 743 the explicit segment to make sure that the constrainsts are met. 745 In another example, an automated way of setting up the TE LSP 746 without any static configuration on the Head-End LSR. In that case, 747 it might require a discovery mechanism of some PCS using IGP 748 extensions (as defined in [OSPF-TE-CAP], for example), as well as 749 some signaling protocol extension to request the computation of an 750 inter-AS TE LSP to a PCS(s) such as one defined in [PATH-COMP]. 752 In addition, The proposed solution SHOULD also provide the ability 753 to specify and signal that certain loose or explicit nodes and 754 resources to be explicitly excluded in the inter-AS TE LSP path 755 establishment, such as one defined in [EXCLUDE-ROUTE] for instance. 757 5.1.3 Optimality 759 The solution SHOULD allow the set up of an inter-AS TE LSP that 760 complies with a set of TE constraints defined in [TE-REQ]) and 761 follow an optimal path. 763 An optimal path is defined as a path whose end-to-end cost is 764 minimal, based upon either an IGP or a TE metric. Note that in 765 the case of an inter-AS path across several ASes having completely 766 different IGP metric policies, the notion of minimal path might 767 require IGP metric normalization, for example. 769 5.1.4 Support of diversely routed inter-AS TE LSP 771 In some cases it might be desirable to set up multiple inter-AS TE 772 LSPs between a pair of LSRs, when: 774 (1) A single TE LSP satisfying the required set of constraints 775 cannot be found, in which case it may require load splitting. 777 (2) Multiple TE paths may be required to limit the impact of a 778 network element failure to a portion of the traffic. As an 779 example, two VoIP gateways may load balance the traffic among 780 a set of inter-AS TE LSPs. 782 (3) Path protection (e.g. 1:1 or 1:N) as discussed in 783 [MPLS-Recov]. 785 In the examples above, being able to set up diversely routed TE LSPs 786 becomes a requirement for inter-AS TE. 788 The solution SHOULD be able to set up a set of link/SRLG/Node 789 diversely routed inter-AS TE LSPs. 791 5.1.5. Re-optimization 793 Once an inter-AS TE LSP has been established and should there be any 794 resource or other changes inside anyone of transiting ASes, the 795 solution MUST be able to re-optimize the LSP accordingly and 796 non-disruptively, either upon expiration of a configurable timer or 797 triggered by a network event or a manual request at the TE tunnel 798 Head-end. 800 The solution SHOULD support the ability for intermediate nodes to 801 signal the respective Head-End LSRs of the existence of a more 802 optimal path. 804 The solution SHOULD also be such that an inter-AS TE LSP is 805 re-signaled again (via make before break) if and only if a more 806 optimal path exists. 808 Furthermore the solution SHOULD provide the ability of manually 809 rejecting re-optimization at AS boundaries. 811 5.1.6. Fast Recovery support using MPLS TE Fast Reroute 813 There are in general two or more inter-AS links between multiple 814 pair of ASBRs for redundancy. The topological density between ASes 815 in a multi-AS SP network is generally much higher. In the event of 816 inter-AS link failure, rapid local protection SHOULD also be made 817 available and interoperate with current intra-AS MPLS TE fast 818 re-route mechanism from [TE-FRR]. 820 Moreover, the traffic routed onto an inter-AS TE tunnel SHOULD also 821 be fast protected against any node failure, should the node be 822 internal to an AS or at the AS boundary. 824 5.1.7. DS-TE Support 826 The proposed inter-AS MPLS TE solution SHOULD also satisfy core 827 requirements documented in [DS-TE] and interoperate seamlessly with 828 current intra-AS MPLS DS-TE mechanism [DSTE-PROT]. 830 It is worth pointing out that the compatibility clause in section 831 4.1 of [DS-TE] SHOULD also be faithfully applied in the development 832 of the solutions. 834 5.1.8. Hierarchical LSP Support and Forwarding Adjacency (FA) 836 It is conceivable that there would potentially be scalability issues 837 as the number of required inter-AS MPLS TE tunnels increases. In 838 order to reduce the number of tunnel states to be maintained by each 839 transiting PoP, the proposed solution SHOULD allow TE LSP 840 aggregation such that individual tunnels can be carried onto one or 841 more aggregating LSP. One such mechanism, for example is described 842 in [MPLS-LSPHIE]. 844 5.1.9. Mapping of traffic onto Multiple Inter-AS MPLS TE Tunnels 846 There SHOULD be several possibilities to map a particular traffic 847 to a particular destination onto a specific inter-AS TE LSP. 849 For example, static routing could be used if IP destination 850 addresses are known. Another example is to utilize static routing 851 using recursive BGP route resolution. 853 In cases where inter-AS MPLS TE tunnels are terminated at P routers 854 in a PoP where there could also be multiple PE routers, the proposed 855 solution SHOULD provide the ability whereby to "announce" the 856 inter-AS MPLS TE tunnels as a link into the IGPs (ISIS or OSPF) with 857 the link's cost associated with it. By doing so, PE routers that do 858 not participate in the inter-AS TE path computation can take into 859 account such links in its IGP-based SPF computation. 861 5.1.10. Inter-AS MPLS TE Management 863 5.1.10.1. Inter-AS MPLS TE MIB Requirements 865 An inter-AS TE MIB is required for use with network management 866 protocols by SPs to manage and configure inter-AS traffic 867 engineering tunnels. This new MIB must extend (and not reinvent) 868 the existing MIBs to accommodate this new functionality. 870 An inter-AS TE MIB should include features, for example: 871 - the setup of inter-AS TE tunnels with associated constraints 872 (e.g. resources) 873 - the collection of traffic and performance statistics not only 874 at the tunnel Headend, but any other points of the TE tunnel. 875 - the inclusion of both IPv4/v6 + AS# or AS# subobjects in the 876 ERO in the path message, e.g: 878 EXPLICIT_ROUTE class object: 879 address1 (loose IPv4 Prefix, /AS1) 880 address2 (loose IPv4 Prefix, /AS1) 881 AS2 (AS number) 882 address3 (loose IPv4 prefix, /AS3) 883 address4 (loose IPv4 prefix, /AS3) - destination 885 or 887 address1 (loose IPv4 Prefix, /AS1) 888 address2 (loose IPv4 Prefix, /AS1) 889 address3 (loose IPv4 Prefix, /AS2) 890 address4 (loose IPv4 Prefix, /AS2) 891 address5 (loose IPv4 prefix, /AS3) 892 address6 (loose IPv4 prefix, /AS3) - destination 894 - Similarly, the inclusion of the RRO object in the resv. message 895 recording subojects such as interface IPv4/v6 address (if not 896 hidden), AS number, a label, a node-id (when required), etc. 897 - inter-AS specific attributes as discussed in section 5 of this 898 document including, for example inter-AS MPLS TE tunnel 899 accounting records across each AS segment. 901 5.1.10.2. Inter-AS MPLS TE Fault Management Requirements 903 In a MPLS network, a SP wants to detect both control plane and data 904 plane failures. But tools for fault detection over LSPs haven't 905 been widely developed so far. SPs today manually troubleshoot such 906 failures in a hop-by-hop fashion across the data path. If they 907 detect an error on the data plane, they have to check the control 908 plane in order to determine where the faults come from. 910 The proposed solution SHOULD be able to interoperate with fault 911 detection mechanisms of intra-AS TE and MAY or MAY NOT require the 912 inter-AS TE tunnel ending addresses to be known or routable across 913 IGP areas (OSPF) or levels(IS-IS) within the transiting ASes with 914 working return paths. 916 For example, [LSPPING] is being considered as a failure detection 917 mechanism over the data plane against the control plane and could 918 be used to troubleshoot intra-AS TE LSPs. Such facilities, if 919 adopted, SHOULD then be extended to inter-AS TE paths. 921 The above example, however depicts one such mechanism that does 922 require a working return path such that diagnostic test packets can 923 return via an alternate data plane, such as a global IPv4 path in 924 the event that the LSP is broken. 926 [MPLS-TTL] presents how TTL may be processed across a hierarchical 927 MPLS networks and such a facility as this SHOULD also be extended 928 to inter-AS TE links. 930 5.2. Requirements for Inter-AS MPLS TE across Multiple SP 931 Administrative Domains. 933 The requirements for inter-AS MPLS TE across multiple SP admin 934 domains SHOULD include all requirements discussed in section 5.1 935 above in addition to what are presented in this section here. 937 Please note that the SP with multi-AS networks may choose not to 938 turn on the features discussed in the following two sections when 939 building TE tunnels across ASes in its own domain. 941 5.2.1. Confidentiality 943 Since an inter-AS TE LSP may span multiple ASes belonging to 944 different SPs, the solution MIGHT allow to "hide" the set of hops 945 used by the TE LSP within an AS as illustrated in the following 946 example: 948 [ ASBR1-----ASBR2 ] 949 [ ] [ ] 950 [ A ] [ B ] 951 [ AS1 ] [ AS2 ] 952 [ SP1 ]-----[ SP2 ] 953 [ ] [ ] 955 Suppose there is an inter-AS TE LSP from A (within AS1 of SP1) to B 956 (within AS2 of SP2). When computing an inter-AS TE LSP path, the 957 set of hops within AS2 might be hidden to AS1. In this case, the 958 solution will allow A to learn that the more optimal TE LSP path to 959 B that complies with the set of constraints traverses ASBR2 without 960 a detailed knowledge of the lists of the hops used within AS2. 962 Optionally, the TE LSP path cost within AS2 could be provided to A, 963 via for example PCC-PCS signaling [PATH-COMP], such that A (PCC) 964 could use this information to compute an optimal path, even if the 965 computed path is not provided by AS2. 967 In addition, the management requirements discussed in section 5.1.10 968 above, when used across different SP admin domains, SHOULD include 969 similar confidentiality requirements discussed here in terms of 970 "hiding" intermediate hops or interface address and/ or labels in 971 the transiting or peering SPs. 973 5.2.2. Policy Control 975 In some cases, some policy control might be necessary at the AS 976 boundaries, namely ingress policy controls enabling SPs to enforce 977 the inter-AS policies per interconnect agreements or modify some 978 requested parameters conveyed by incoming inter-AS MPLS TE signaling 979 requests. 981 It is worth noting that such policy control mechanism may also be 982 used between ASes within a SP. 984 This section only discusses the elements that may be used to form a 985 set of ingress control policies. However, how exactly SPs establish 986 bilateral or multilateral agreements upon which the control policies 987 can be built are beyond the scope of this document. 989 5.2.2.1. Inter-AS TE Agreement Enforcement Polices 991 The following provides a set of TE-LSP parameters in the inter-AS TE 992 requests(RSVP Path Message) that could be enforced at the AS 993 boundaries: 995 - RSVP-TE session attributes: affinities and preemption 996 priorities 997 - Per AS or SP bandwidth admission control to ensure that RSVP-TE 998 messages do not request for bandwidth resources over their 999 allocation. 1000 - Request origins which can be represented by HE tunnel ending IP 1001 address, originating AS#, neighbor AS#, neighbor ASBR interface 1002 IP address, etc. 1003 - DS-TE TE-Class . 1004 - FRR attribute: local protection desired bit, node protection 1005 desired bit and bandwidth protection desired bit carried in the 1006 SESSION 1007 - ATTRIBUTE or the FAST-REROUTE objects in the RSVP Path message 1008 as defined in [TE-FRR]. 1009 - Optimization allowed or not. 1011 In some cases, a TE policy server could also be used for the 1012 enforcement of inter-AS TE policies. This requirement could allow 1013 SPs to make the inter-AS TE policies scale better. 1015 The signaling of a non policy compliant request MUST trigger the 1016 generation of a RSVP Path Error message by the policy enforcing 1017 node towards the Head-end LSR, indicating the cause. The 1018 Head-end LSR SHOULD take appropriate actions, such as re-route, upon 1019 receipt of such a message. 1021 5.2.2.2. Inter-AS TE Rewrite Policies 1023 In some situations, SPs may need to rewrite some attributes of the 1024 incoming inter-AS TE signaling requests due to for example, a lack 1025 of resources for a particular TE-Class, non compliant preemption, 1026 upon mutual agreements. The following lists a set of parameters 1027 that can potentially be rewritten at the AS boundaries: 1029 - RSVP-TE session attributes: affinities and preemption 1030 priorities 1031 - DS-TE TE-Class . 1032 - ERO expansion requests 1034 Simimarly, the re-writing node MUST generate a RSVP Path Error 1035 Message towards the Head-end LSR indicating the cause in terms 1036 of types of changes made so as to maintain the end-to-end integrity 1037 of inter-AS TE LSP. 1039 5.2.2.3 Inter-AS Traffic Policing 1041 The proposed solution SHOULD also provide a set of policing 1042 mechanisms which could be configured on the inter-AS links, 1043 to ensure that traffic routed through the tunnel does not exceed 1044 the bandwidth negotiated during LSP signaling. 1046 For example, an ingress policer could be configured to enforce 1047 the traffic contract on the mutually agreed resource requirements 1048 of the established inter-AS TE LSP (i.e. RSVP bandwidth) on the 1049 interface to which the inter-AS link is connected. 1051 6. Evaluation Criteria 1053 There may be multiple solutions to satisfy the requirements for 1054 Inter-AS MPLS TE presented in previous sections. 1056 This section provides general guidelines, which could be applied in 1057 the selection of an optimum solution. 1059 6.1. Detailed Requirement Satisfactions 1061 The proposed solution SHOULD include at least all of the 1062 Application Scenarios presented in section 4 above. It MUST meet all 1063 the requirements described in section 5 each time a MUST is 1064 specified. 1066 6.2. Scalability and Extensibility 1068 The proposed solution(s) MUST have minimum impact on the network 1069 scalability from both intra and inter-AS perspectives. 1071 This requirement applies to both of the following: 1073 - IGP (impact in terms of IGP flooding, SPF, etc.). 1074 - BGP (impact in terms of additional information carried within 1075 BGP, number of routes, flaps, overload events, etc.). 1076 - RSVP TE (message rate, number of retained states, ,etc.). 1078 In addition, the solution(s) MUST allow extensions as both inter-AS 1079 MPLS TE and current intra-AS MPLS TE specifications evolve. 1081 6.3. Complexity and Risks 1083 The proposed solution (s) SHOULD not introduce unnecessary 1084 complexity to the current operating network to such a degree that it 1085 would affect the stability and diminish the benefits of deploying 1086 such solution over SP networks. 1088 6.4. Performance 1090 The solution SHOULD be evaluated taking into account various 1091 performance criteria: 1093 - Degree of path optimality of the inter-AS TE LSP path 1094 - TE LSP setup time. 1095 - Fail and restoration time 1097 Other criteria might be added as this draft will evolve. 1099 6.5. Backward Compatibility 1101 The deployment of inter-AS MPLS TE SHOULD not have impact on 1102 existing BGP-based traffic engineering or MPLS TE mechanisms to 1103 allow for a smooth migration or co-existence. 1105 7. Security Considerations 1107 The proposed solution(s) MUST address security issues across 1108 multiple SP administrative domains. Although inter-AS MPLS TE is 1109 not expected to add specific security extensions beyond those of 1110 current intra-AS TE, greater considerations MUST be given in terms 1111 of how to establish a trusted model across AS boundaries. SPs 1112 SHOULD have a means to authenticating, such as using RSVP INTEGRITY 1113 object, allowing and possibly denying inter-AS signaling requests 1114 and SHOULD be protected from DoS attacks. 1116 8. Acknowledgement 1118 We would like to thank Yuichi Ikejiri, David Allan, Kurt Erik 1119 Lindqvist, Dave McDysan, Christian Jacquenet, Kireeti Kompella, 1120 Ed Kern, Jim Boyle and Thomas Nadeauor for their suggestions and 1121 helpful comments during the discussions of this draft. 1123 9. Editor's Addresses 1125 Raymond Zhang 1126 Infonet Services Corporation 1127 2160 E. Grand Ave. 1128 El Segundo, CA 90025 1129 USA 1130 Email: raymond_zhang@infonet.com 1132 JP Vasseur 1133 CISCO Systems, Inc. 1134 300 Beaver Brook Road 1135 Boxborough , MA - 01719 1136 USA 1137 Email: jpv@cisco.com 1139 10. Normative References 1141 [TE-REQ], Awduche et. al., "Requirements for Traffic Engineering 1142 over MPLS", RFC2702, September 1999. 1144 [TE-RSVP], Awduche et. al., "RSVP-TE: Extensions to RSVP for LSP 1145 Tunnels", RFC 3209, December 2001 1147 [GMPLS-ROUT], Kompella, et. al., "RGeneralized Multi-Protocol Label 1148 Switching (GMPLS) Signaling Resource ReserVation Protocol-Traffic 1149 Engineering (RSVP-TE) Extensions, RFC 3473, January 2003. 1151 [BGP], Rekhter, et. al., "A Border Gateway Protocol 4 (BGP-4)", 1152 RFC 1771, March 1995 1154 [LSPPING], Kompella, et.. al.," Detecting Data Plane Liveliness in 1155 MPLS", Internet Draft , June 2003, 1156 (Work in Progress) 1158 [MPLS-TTL], Agarwal, et. al., "Time to Live (TTL) Processing in MPLS 1159 Networks", RFC 3443, January, 2003 1161 [DS-TE], Le Faucheur, et. al., ''Requirements for support of 1162 DiffServ-aware MPLS Traffic Engineering'', RFC 3564, July, 2003 1164 [DSTE-PROT], Le Faucheur, et. al., "Protocol extensions for support 1165 of Diff-Serv-aware MPLS Traffic Engineering", draft-ietf-tewg-diff 1166 -te-proto-05.txt, September, 2003 (Work in Progress). 1168 [TE-FRR], Pan, et. al., "Fast Reroute Techniques in RSVP-TE", 1169 draft-ietf-mpls-rsvp-lsp-fastreroute-03.txt, June 2003 1170 (Work in Progress). 1172 [ISIS-TE], Smit, Li, "IS-IS extensions for Traffic Engineering", 1173 draft-ietf-isis-traffic-05.txt, August, 2003 (Work in Progress). 1175 [OSPF-TE] Katz, Yeung, "Traffic Engineering Extensions to OSPF", 1176 draft-ietf-ospf-ospfv3-traffic-01.txt, June, 2001 1177 (Work in Progress). 1179 [PATH-COMP], Vasseur, et. al., ''RSVP Path computation request and 1180 reply messages'', draft-vasseur-mpls-computation-rsvp-03.txt, June 1181 2002. (Work in Progress) 1183 [OSPF-TE-CAP], Vasseur, Psenak. "OSPF TE TLV capabilities", 1184 draft-vasseur-mpls-ospf-te-cap-00.txt, October 2002. 1185 (Work in Progress) 1187 [MPLS-LSPHIE] Kompella, Rekhter, "LSP Hierarchy with Generalized 1188 MPLS TE", draft-ietf-mpls-lsp-hierarchy-08.txt , March 2002. 1189 (work in progress) 1191 [MPLS-Recov], Sharma V., et al, "Framework for Multi-Protocol Label 1192 Switching (MPLS)-based Recovery", RFC 3469, Feb, 2003 1194 [BGP-Label], Rekhter and Rosen, "Carrying Label Information in 1195 BGP-4", RFC 3107, May 2001 1197 [INTER-AS-TE], Vasseur and Zhang, "Inter-AS MPLS Traffic 1198 Engineering", draft-vasseur-inter-as-te-01.txt, June, 2003 (work 1199 in progress). 1201 [EXCLUDE-ROUTE], Farrel, et. al., "draft-ietf-ccamp-rsvp-te-exclude 1202 -route-00.txt", June 2003 (work in progress). 1204 11. Informative References 1206 [MPLS-ARCH], Rosen, et. al., "Multiprotocol Label Switching 1207 Architecture", RFC 3031, January 2001 1209 [BGP-MPLSVPN], Rosen, et. al., "BGP/MPLSVPN", draft-ietf-l3vpn 1210 -rfc2547bis-01.txt, July 2002 (work in progress). 1212 [DIFF_ARCH], Blake, et. al., "An Architecture for Differentiated 1213 Services", RFC 2475, December 1998. 1215 [DIFF_AF], Heinanen,et. al., "Assured Forwarding PHB Group", RFC 1216 2597, June 1999. 1218 [DIFF_EF], Davie, et. al., "An Expedited Forwarding PHB (Per-Hop 1219 Behavior)", RFC 3246, March 2002. 1221 [MPLS-Diff], Le Faucheur, et. al., "MPLS Support of Differentiated 1222 Services", RFC 3270, May 2002 1224 [TE-OVW], Awduche, et. al., "Overview and Principles of Internet 1225 Traffic Engineering", RFC 3272,May 2002 1227 [PSTE], Li, et. al., "A Provider Architecture for Differentiated 1228 Services and Traffic Engineering", RFC 2430, October 1998 1230 [TE-APP], Boyle, et. al., "Applicability Statement of Traffic 1231 Engineering", RFC 3346, August 2002. 1233 [TE-SURVIV], Lai, et. al., "Network Hierachy and Multilayer 1234 Suvivability", RFC 3386, November, 2002. 1236 12. Full Copyright Statement 1238 Copyright (C) The Internet Society (2003). All Rights Reserved. 1240 This document and translations of it may be copied and furnished to 1241 others, and derivative works that comment on or otherwise explain it 1242 or assist in its implementation may be prepared, copied, published 1243 and distributed, in whole or in part, without restriction of any 1244 kind, provided that the above copyright notice and this paragraph 1245 are included on all such copies and derivative works. However, this 1246 document itself may not be modified in any way, such as by removing 1247 the copyright notice or references to the Internet Society or other 1248 Internet organizations, except as needed for the purpose of 1249 developing Internet standards in which case the procedures for 1250 copyrights defined in the Internet Standards process MUST be 1251 followed, or as required to translate it into languages other than 1252 English. 1254 The limited permissions granted above are perpetual and will not be 1255 revoked by the Internet Society or its successors or assigns. 1257 This document and the information contained herein is provided on an 1258 "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING 1259 TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING 1260 BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION 1261 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF 1262 MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 1264 Appendix A. Brief Description of BGP based Inter-AS Traffic 1265 Engineering 1267 In today's Service Provider (SP) network, BGP is deployed to meet 1268 two different sets of requirements: 1270 - Establishing a scalable exterior routing plane separating from 1271 data forwarding plane within SP's administrative domain 1272 - Exchanging network reachability information with different BGP 1273 autonomous systems (ASes) that could belong to a different SP 1274 or simply, a different AS within a SP network. 1276 Over connections across the AS boundaries, traffic engineering may 1277 also be accomplished via a set of BGP capabilities by appropriately 1278 enforcing BGP-based inter-AS routing policies. The current 1279 BGP-based inter-AS traffic engineering practices may be summarized 1280 as follows: 1282 - "Closest exit" routing where egress traffic from one SP to 1283 another follows the path defined by the lowest IGP or intra-AS 1284 MPLS TE tunnel metrics of the BGP next-HOP of exterior routes 1285 learned from other AS over the inter-AS links 1286 - "BGP path attribute" based routing selection mechanism where 1287 the egress traffic path is determined by interconnect (peering 1288 or transit) policies based upon one or a combination of BGP 1289 path attributes, like AS_PATH, MULTI_EXIT_DISC (MED), and 1290 Local_Pref. 1292 SPs have often faced a number of un-deterministic factors in their 1293 practices of inter-AS traffic engineering employing the methods 1294 mentioned above: 1296 - Sub-optimum traffic distribution across inter-AS links 1297 - Un-deterministic traffic condition changes due to uncoordinated 1298 IGP routing policies or topology changes within other AS and 1299 uncoordinated BGP routing policy changes (MED or as-prepend, 1300 etc.) 1302 In addition, to achieve some degrees of granularity, SPs may choose 1303 to enforce BGP inter-AS policies that are specific to one or a set 1304 of inter-AS links for ingress traffic destined to certain PoPs or 1305 regions within SP's network from another AS by tagging certain sets 1306 of routes with a specific attribute when announcing to another AS. 1307 This of course goes under the assumption that the other AS permits 1308 automated egress policy by matching the predefined attribute from 1309 incoming routes.