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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 a 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 (December 2003) is 7437 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 1167, but no explicit reference was found in the text == Unused Reference: 'OSPF-TE' is defined on line 1170, but no explicit reference was found in the text == Unused Reference: 'OSPF-TE-CAP' is defined on line 1178, but no explicit reference was found in the text == Unused Reference: 'BGP-Label' is defined on line 1189, but no explicit reference was found in the text == Unused Reference: 'INTER-AS-TE' is defined on line 1192, but no explicit reference was found in the text == Unused Reference: 'TE-SURVIV' is defined on line 1228, 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 (~~), 15 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-03.txt CISCO Systems, Inc 5 December 2003 6 Expires: June 2004 8 MPLS Inter-AS Traffic Engineering requirements 9 draft-ietf-tewg-interas-mpls-te-req-03.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....9 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...................15 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. Scalability and Hierarchical LSP Support......................17 94 5.1.9. Mapping of traffic onto Inter-AS MPLS TE Tunnels..............17 95 5.1.10. Inter-AS MPLS TE Management..................................18 96 5.1.10.1. Inter-AS MPLS TE MIB Requirements..........................18 97 5.1.10.2. Inter-AS MPLS TE Fault Management Requirements.............18 98 5.1.11. Extensibility................................................19 99 5.1.12. Complexity and Risks.........................................19 100 5.1.13. Backward Compatibility.......................................19 101 5.2. Requirements for Inter-AS MPLS TE across Multiple SP 102 Administrative Domains..........................................19 103 5.2.1. Confidentiality...............................................19 104 5.2.2. Policy Control................................................20 105 5.2.2.1. Inter-AS TE Agreement Enforcement Polices...................20 106 5.2.2.2. Inter-AS TE Rewrite Policies................................21 107 5.2.2.3 Inter-AS Traffic Policing....................................21 108 6. Evaluation Criteria...............................................22 109 6.1. Detailed Requirement Satisfactions..............................22 110 6.2. Performance.....................................................22 111 7. Security Considerations...........................................22 112 8. Acknowledgement...................................................22 113 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 CE: Customer Edge Equipment 263 PE: Provider Edge Equipment that has direct connections to CEs. 265 P: Provider Equipment that has backbone trunk connections only. 267 VRF: Virtual Private Network (VPN) Routing and Forwarding Instance. 269 PoP: Point of presence or a node in SP's network. 271 SRLG: A set of links may constitute a 'shared risk link group' 272 (SRLG) if they share a resource whose failure may affect all 273 links in the set as defined in [GMPLS-ROUT]. 275 Please note that the terms of CE, PE and P used throughout this 276 document are generic in their definitions. In particular, whenever 277 such acronyms are used, it does not necessarily mean that CE is 278 connected to a PE in a VRF environment described in such IETF drafts 279 as [BGP-MPLSVPN]. 281 3.2. Objectives and Requirements of Inter-AS Traffic Engineering 283 As mentioned in section 1 above, some SPs have requirements for 284 achieving the same set of traffic engineering objectives as 285 presented in [TE-OVW] across AS boundaries. 287 This section examines these requirements in each of the key 288 corresponding areas: 1) Inter-AS bandwidth guarantees; 2) 289 Inter-AS Resource Optimization and 3) Fast Recovery across ASes, 290 i.e. Recovery of Inter-AS Links/SRLG and ASBR Nodes. 292 3.2.1. Inter-AS Bandwidth Guarantees 294 The DiffServ IETF working group has defined a set of mechanisms 295 described in [DIFF_ARCH], [DIFF_AF] and [DIFF_EF] or [MPLS-Diff] 296 that can be activated at the edge or over a DiffServ domain to 297 contribute to the enforcement of a (set of) QoS policy(ies), which 298 can be expressed in terms of maximum one-way transit delay, 299 inter-packet delay variation, loss rate, etc. 301 Many SPs have some or full deployment of Diffserv implementations in 302 their networks today, either across the entire network or at the 303 least, on the edge of the network across CE-PE links. 305 In situations where strict QOS bounds are required, admission 306 control inside the backbone of a network is in some cases required 307 in addition to current Diffserv mechanisms. 309 When the propagation delay can be bounded, the performance targets, 310 such as maximum one-way transit delay may be guaranteed by providing 311 bandwidth guarantees along the Diffserv-enabled path. 313 One typical example of this requirement is to provide bandwidth 314 guarantees over an end-to-end path for VoIP traffic classified as EF 315 (Expedited Forwarding [DIFF_EF]) class in a Diffserv-enabled 316 network. When the EF path is extended across multiple ASes, 317 inter-AS bandwidth guarantee is then required. 319 Another case for inter-AS bandwidth guarantee is the requirement for 320 guaranteeing a certain amount of transit bandwidth across one or 321 multiple ASes. 323 Several application scenarios are presented to further illustrate 324 this requirement in section 4 below. 326 3.2.2. Inter-AS Resource Optimization 328 In Service Provider (SP) networks, the BGP protocol [BGP] is 329 deployed to exchange routing information between ASes. The inter-AS 330 capabilities of BGP may also be employed for traffic engineering 331 purposes across the AS boundaries. Appendix A provides a 332 brief description of the current BGP-based inter-AS traffic 333 engineering practices. 335 SPs have managed to survive with this coarse set of BGP-based 336 traffic engineering facilities across inter-AS links in a largely 337 best effort environment. Certainly in many cases ample bandwidth 338 within SP's network and across inter-AS links reduces the need for 339 more elaborated inter-AS TE policies. 341 However, in the case where a SP network is deployed over multiple 342 ASes, for example, as the number of inter-AS links grows, the 343 complexity of the inter-AS policies and the difficulty in inter-AS 344 TE path optimization increase to a level such that it may soon 345 become unmanageable. 347 Another example is where inter-AS links are established between 348 different SP administrative domains. Un-deterministic factors such 349 as un-coordinated routing and network changes as well as sub-optimum 350 traffic conditions would potentially lead to a complex set of 351 Inter-AS traffic engineering policies where current traffic 352 engineering mechanisms would probably not scale well. 354 In these situations where resource optimization is required and/ or 355 specific routing requirements arise, the BGP-based inter-AS 356 facilities will need to be complemented by a more granular inter-AS 357 traffic engineering mechanism. 359 3.2.3. Fast Recovery across ASes 361 When extending services such as VoIP across ASes, customers often 362 demands SPs to maintain the same level of performance targets such 363 as packet loss and service availability as ones that can be achieved 364 within an AS. As a consequence, fast convergence in a stable 365 fashion upon link/SRLG/node failures becomes a strong requirement. 366 This is clearly difficult to achieve with current inter-domain 367 techniques, especially in cases of link/SRLG failures between ASBRs 368 or ASBR node failures. 370 3.3. Inter-AS Traffic Engineering Requirements Statement 372 Just as in the applicable case of deploying MPLS TE in a SP's 373 network, an inter-AS TE method in addition to BGP-based traffic 374 engineering capabilities needs to be deployed across inter-AS links 375 over where resource optimization, QOS guarantees and fast recovery 376 are required. 378 This is especially critical in a Diffserv-enabled, multi-class 379 environment described in [PSTE] where statistical performance 380 targets must be maintained consistently over the entire path 381 across different ASes. 383 The approach of extending current intra-AS MPLS TE capabilities 384 [TE-RSVP] across inter-AS links for IP/MPLS networks is considered 385 here because of already available implementations and operational 386 experiences. 388 Please note that the inter-AS traffic engineering over an IP-only 389 network is for future consideration since there is no sufficient 390 interest for similar requirements to those of IP/MPLS networks 391 at this time. More specifically, this document only covers the 392 inter-AS TE requirements for packet based IP/MPLS networks. 394 4. Application Scenarios 396 The following sections present a few application scenarios over 397 IP/MPLS networks where requirements cannot be addressed with current 398 intra-AS MPLS TE mechanism and give rise to considerations for 399 inter-AS MPLS traffic engineering requirements. 401 Although not explicitly noted in the following discussions, fast 402 recovery of traffic path(s) crossing multiple ASes in a stable 403 fashion is particularly important in case of link/SRLG/node failures 404 at AS boundaries for all application scenarios presented here. 406 4.1. Application Scenarios Requiring Inter-AS Bandwidth Guarantees 408 4.1.1 Scenario I - Extended or Virtual PoP (VPoP) 410 A global service provider (SP1), for example would like to expand 411 its reach in a region where a regional service provider's (SP2) 412 network has already established an extended coverage in its PoP 413 density. 415 In this scenario, the SP1 may establish interconnections with SP2 in 416 one or multiple points in that region. It may then use SP2's 417 network as an extended transport by co-locating aggregation routers 418 in some SP2's PoPs that are in the regions where SP1 has a larger 419 number of customer sites. 421 In order to ensure bandwidth capacity provided by SP2 and achieve 422 some degrees of transparency to SP2's network changes in terms of 423 capacity and network conditions, one or more Inter-AS MPLS TE 424 trunk(s) can be built between SP1's ASBR or PE router inside AS1 and 425 SP1's PE routers co-locating in SP2's PoPs, as illustrated in the 426 diagram below: 428 <===========Inter-AS MPLS TE Tunnel===========> 429 ----- ----- 430 ________|ASBR |___Inter-AS___|ASBR |________ 431 | | RTR | Link | RTR | | 432 ---- ----- ----- ----- ----- 433 |SP1 |_____| SP2 | | SP1 | 434 |VPoP| |P/PE | |P/PE | 435 ---- ----- ----- ----- ----- 436 |________|ASBR |___Inter-AS___|ASBR |________| 437 | RTR | Link | RTR | 438 ----- ----- 439 <=================Inter-AS MPLS TE Tunnel=================> 440 +-SP1 AS1-+ +-------SP2 AS2-----+ +------SP1 AS1------+ 442 In situations where end-to-end Diffserv paths must be maintained, 443 both SP's networks may need to provision Diffserv PHB at each hop 444 supporting a set of traffic classes with compatible performance 445 targets. The subsequent issues regarding Service Level Agreement 446 (SLA) boundaries, reporting and measuring system inter-operability 447 and support demarcations are beyond the scope of this document and 448 will therefore not be discussed here. 450 Note also that either the SP1 or SP2 network may not be a 451 Diffserv-aware network. The scenario would still apply to provide 452 bandwidth guarantees. 454 The SP2, on the other hand, can similarly choose to expand its reach 455 beyond its servicing region over SP1's network via inter-AS MPLS 456 TE paths. 458 It is worth mentioning that these remote aggregation routers 459 co-located in other SP's network will unlikely participate in 460 hosting SP's IGP and BGP routing planes and will most likely 461 maintain its own AS or be part of the SP1's AS. In this case, such 462 TE tunnels may cross several ASes, but the Head-end and Tail-end 463 LSRs of TE tunnel may have the same AS number, as shown in the 464 diagram above. 466 4.1.2. Scenario II - Extended or Virtual Trunk 468 Instead of co-locating a PE router in SP2's PoP, SP1, for example 469 may also choose to aggregate customer VPN sites onto a SP2's PE 470 router where inter-AS TE tunnels can be built and signaled through 471 SP2's MPLS network between the SP2 PoP (to which SP1 customer CEs 472 are directly connected) and SP1's ASBR or PE routers inside SP2's 473 network. This allows SP1�s customers connected to SP2 PE router to 474 receive a guaranteed bandwidth service up to the TE LSP tail-end 475 router located in SP1's network. 477 In this scenario, there could be two applicable cases: 479 Case 1 - the inter-AS MPLS TE tunnel functions as an extended or 480 virtual trunk aggregating SP1 CE's local-loop access circuits on 481 SP2's MPLS network over which the bandwidth can be guaranteed to the 482 TE LSP tail-end router located in SP1�s network, as shown in the 483 diagram below: 485 <====Inter-AS MPLS TE Tunnel====> 486 or 487 < ===Inter-AS MPLS TE Tunnel===============> 489 ---- ----- ----- ----- ----- 490 | CE |_____Local___| SP2 |___|ASBR |___Inter-AS___|ASBR |___|SP1 | 491 | | Loop | PE | | RTR | Link | RTR | |PE | 492 ---- ----- ----- ----- ----- 494 +SP1 Customer AS3+ +-----SP2 AS2---+ +-SP1 AS1-------+ 496 Case 2 - the inter-AS MPLS TE tunnel in this case functions as an 497 extended or virtual local access link from SP1's CE on SP2's network 498 to the SP1's ASBR or PE: 500 <==============Inter-AS MPLS TE Tunnel==============> 501 or 502 <==============Inter-AS MPLS TE Tunnel========================> 504 ---- ----- ----- ----- ----- 505 | CE |____Local_____| SP2 |___|ASBR |___Inter-AS___|ASBR |___|SP1 | 506 | | Loop | PE | | RTR | Link | RTR | |PE | 507 ---- ----- ----- ----- ----- 509 +SP1 Customer AS3+ +------SP2 AS2---+ +--SP1 AS1-----+ 510 In case 2 above, SP2 may elect to establish an aggregating or 511 hierarchical intra-AS MPLS TE tunnel between the transiting P or PE 512 router and SP2's ASBR router just to reduce the number of tunnel 513 states signaled from the SP2 PE to where SP1's CEs are connected. 515 4.1.3. Scenario III - End-to-end Inter-AS MPLS TE From CE to CE 517 In this scenario as illustrated below, customers require to 518 establish MPLS TE tunnel from CE1 to CE2 end-to-end across several 519 SP's networks. One application example would be the guaranteed 520 bandwidth for voice- or video-over-IP services. 522 <======================Inter-AS MPLS TE Tunnel==================> 524 --- ----- ----- ----- ----- --- 525 |CE1|_____| SP2 |___|ASBR |__Inter-AS__|ASBR |____| SP1 |_____|CE2| 526 | | | PE | | RTR | Link | RTR | | PE | | | 527 --- ----- ----- ----- ----- --- 529 +Cust AS1+ +---SP2 AS-----+ +-------SP1 AS-------+ +Cust ASx+ 531 The diagram below illustrates another example where CE1 and CE2 are 532 customers of SP1 with eBGP peering relationships established across 533 the CE-PE links. A inter-AS MPLS TE tunnel may then be established 534 from CE1 in AS1 to CE2 which may belong to the same AS or different 535 AS than that of CE1 across SP1's network in AS2. 537 <===============Inter-AS MPLS TE Tunnel=====================> 539 --- ----- ---- ---- ----- --- 540 |CE1|______| SP1 |_____|SP1 |____|SP1 |____| SP1 |_________|CE2| 541 | | | PE1 | |P1 | |P2 | | PE2 | | | 542 --- ----- ---- ---- ----- --- 544 +-Cust AS1-+ +-------------SP1 AS2----------------+ +-Cust ASx-+ 546 The above example shows that SP1's network has a single AS. 547 Obviously, there may be multiple ASes between CE1 and CE2 as well in 548 the SP1's network. 550 In addition, where both CE1 and CE2 residing in the same AS, they 551 likely share the same private AS number. 553 Scenario III however, will not scale well should there be a larger 554 number of inter-AS TE MPLS tunnels in some degrees of partial mesh 555 or full mesh. Therefore, it is expected that this scenario will 556 not have a large number of deployments, unless some mechanisms such 557 as hierarchical intra-AS TE-LSPs are used to reduce the number of 558 signaling states 560 4.2. Application Scenarios Requiring Inter-AS Resource Optimization 562 The scenarios presented in this section mainly deal with inter-AS 563 resource optimization. 565 4.2.1. Scenario IV - TE across multi-AS within a Single SP 566 Administrative Domain 568 As mentioned in [TE-APP], SPs have generally admitted that the 569 current MPLS TE mechanism provides a great deal of tactical and 570 strategic values in areas of traffic path optimization [TE-RSVP] and 571 rapid local repair capabilities [TE-FRR] via a set of on-line or 572 off-line constraint-based searching algorithms. 574 From a service provider's perspective, another way of stating the 575 objectives of traffic engineering is to be able to deliver more 576 customer traffic with already available capacity in the network 577 without violating performance targets, and/ or to provide better QOS 578 services via an improved network utilization, operating more likely 579 below congestion thresholds. 581 It is worth noting that situations where resource provisioning is 582 not an issue, e.g. low density in inter-AS connectivity or ample 583 inter-AS capacity may not require more scalable and granular TE 584 facilities beyond BGP routing policies since such policies could be 585 rather simple and because inter-AS resource optimization is not an 586 absolute requirement. 588 However many SPs, especially those with networks across multiple 589 continents as well as sparsely connected, have designed their 590 multi-AS routing policies, for example, along or within the 591 continental or sub-continental boundaries where the number of ASes 592 can range from a very few to dozens. Generally, inter-continent or 593 sub-continent capacity is very expensive. Some Service Providers 594 have multiple ASes in the same country and would like to optimize 595 resources over their inter-region links. This would demand a 596 more scalable degree of resource optimization, which warrants the 597 consideration of extending current intra-AS MPLS TE capabilities 598 across inter-AS links. 600 In addition, one may only realize higher efficiency in conducting 601 traffic optimization and path protection/ restoration planning when 602 coordinating all network resources (not partially) as a whole. For 603 a network which may consist of many ASes, this could be realized via 604 the establishment of inter-AS TE LSPs as shown in the diagragm 605 below: 607 <===================Inter-AS MPLS Tunnel=============> 608 -------- -------- -------- 609 | |_______________| |____________| | 610 | SP1 |_______________| SP1 |____________| SP1 | 611 | AS1 |_______________| AS2 |____________| AS3 | 612 | | | | | | 613 -------- -------- -------- 614 || || 615 || --------- || 616 ||___________________| SP1 |________________|| 617 |____________________| AS4 |_________________| 618 | | 619 --------- 620 The motivation for inter-AS MPLS TE is even more prominent in a 621 Diffserv-enabled network over which statistical performance targets 622 are to be maintained from any point to any point of the network as 623 illustrated in the diagram below with an inter-AS DS-TE LSP: 625 <===================Inter-AS MPLS DS-TE Tunnel=============> 626 ---- ----- ----- ----- ----- ---- 627 | PE |__| P |___|ASBR |___Inter-AS___|ASBR |___|P |___|PE | 628 | RTR| | RTR | | RTR | Link | RTR | |RTR | |RTR | 629 ---- ----- ----- ----- ----- ---- 630 +------------SP1 AS1---------+ +------------SP1 AS2------+ 632 For example , the inter-AS MPLS DS-TE LSP shown in the diagram above 633 could be used to transport a set of L2 Pseudo Wires or VoIP traffic 634 with corresponding QoS requirement. 636 Furthermore, fast recovery in case of ASBR-ASBR link failure or ASBR 637 node failure is a strong requirement for such services. 639 4.2.2. Scenario V - Transit ASes as Primary and Redundant Transport 641 Scenario V presents another possible deployment case. SP1 with AS1 642 wants to link a regional network to its core backbone by building an 643 inter-AS MPLS TE tunnel over one or multiple transit ASes belonging 644 to SP2, SP3, etc. as shown in the following diagram: 646 <===========Inter-AS MPLS TE Tunnel=======> 647 [ ] [ ] [ ] 648 [ ---- ---- ] [ ---- ---- ] [ ---- ---- ] 649 [ |P/PE|__|ASBR|]_Inter-AS_[|ASBR|.|ASBR|]_Inter-AS_[|ASBR| |P/PE|] 650 [ |RTR | |RTR |] Link [|RTR | |RTR |] Link [|RTR | |RTR |] 651 [ ---- ---- ] [ ---- ---- ] [ ---- ---- ] 652 [ ] [ ] [ ] 653 <================Inter-AS MPLS TE Tunnel=====================> 654 +SP1 Regional ASx+ +Transit SP2 AS2,etc...SPi ASi+ +------SP1 AS1-+ 656 This scenario can be viewed as a broader case of Scenario I shown in 657 section 4.1.1 where the "VPoP" could be expanded into a regional 658 network of SP1. By the same token, the AS number for SP1's 659 regional network ASx may be the same as or different from AS1. 661 The inter-AS MPLS TE LSP in this case may also be used to backup an 662 internal path as depicted in the diagram below, although this could 663 introduce routing complexities: 665 <===========Inter-AS MPLS TE Tunnel=======> 666 +----------------------------SP1 AS1-----------------------------+ 667 [ ] 668 [ ---- ---- ---- ---- ] 669 [ |P/PE|__|ASBR|__________Primary Intera-AS________|P | |PE |] 670 [ |RTR | |RTR | Link |RTR | |RTR |] 671 [ ---- ---- ---- ---- ] 672 [ | | ] 673 [ ---- ---- ] 674 [ |ASBR| |ASBR| ] 675 [ |RTR | |RTR | ] 676 [ ---- ---- ] 677 ^ | | ^ 678 | | | | 679 | | [ ] | | 680 | | [ ---- ---- ] | | 681 | |__ Inter-AS_[|ASBR|..|ASBR|]_Inter-AS_| | 682 | Link [|RTR | |RTR |] Link | 683 | [ ---- ---- ] | 684 | [ ] | 685 | | 686 +======Backup Inter-AS MPLS TE Tunnel======+ 687 +Transit SP2 AS2,SP3 AS3,etc....SPi ASi+ 689 5. Detailed Requirements for Inter-AS MPLS Traffic Engnineering 691 This section discusses detailed requirements for inter-AS MPLS TE in 692 two principal areas: 1) requirements for inter-AS MPLS TE in the 693 same SP administrative domain and 2) requirements for inter-AS MPLS 694 TE across different SP administrative domains. 696 5.1. Requirements within one SP Administrative Domain 698 This section presents detailed requirements for inter-AS MPLS TE 699 within the same SP administrative domain. 701 5.1.1. Inter-AS MPLS TE Operations and Interoperability 703 The inter-AS MPLS TE solution SHOULD be consistent with requirements 704 discussed in [TE-REQ] and the derived solution MUST be such that 705 it will interoperate seamlessly with current intra-AS MPLS TE 706 mechanism and inherit its capability sets from [TE-RSVP]. 708 The proposed solution SHOULD allow to provision at the Head/Tail end 709 with end-to-end RSVP signaling (eventually with loose paths) 710 traversing across the interconnected ASBRs, without further 711 provisioning required along the transit path. 713 5.1.2. Protocol Signaling and Path Computations 715 One can conceive that an inter-AS MPLS TE tunnel path signaled 716 across inter-AS links consists of a sequence of intra-AS segments. 718 The proposed solution SHOULD provide the ability to either 719 explicitly select or auto-discover the following elements 720 when signaling the inter-AS TE LSP path: 722 - a set of AS numbers as loose HoPs 723 - a set of LSRs including ASBRs 725 and to specify the above elements in the ERO and record them in the 726 RRO of the Resv message just to keep track of the set of ASes or 727 ASBRs traversed by the inter-As TE LSP. 729 In the case of establishing inter-AS TE LSP traversing multiple ASes 730 within the same SP networks, the solution SHOULD also allow the 731 Headend LSR to explicitly specify the hops across anyone of 732 the transiting ASes and the TE tunnel headhend SHOULD also check 733 the explicit segment to make sure that the constrainsts are met. 735 In addition, The proposed solution SHOULD also provide the ability 736 to specify and signal that certain loose or explicit nodes (e.g. AS 737 numbers, etc.) and resources to be explicitly excluded in the 738 inter-AS TE LSP path establishment, such as one defined in 739 [EXCLUDE-ROUTE] for instance. 741 5.1.3 Optimality 743 The solution SHOULD allow the set up of an inter-AS TE LSP that 744 complies with a set of TE constraints defined in [TE-REQ]) and 745 follow an optimal path. 747 An optimal path is defined as a path whose end-to-end cost is 748 minimal, based upon either an IGP or a TE metric. Note that in 749 the case of an inter-AS path across several ASes having completely 750 different IGP metric policies, the notion of minimal path might 751 require IGP metric normalization, for example. 753 The solution SHOULD provide mechanism(s) to compute and establish an 754 optimal end-to-end path for the inter-AS TE LSP and SHOULD also 755 allow for reduced suboptimality since the path may not remain 756 optimal for the life-time of the LSP 758 5.1.4 Support of diversely routed inter-AS TE LSP 760 In some cases it might be desirable to set up multiple inter-AS TE 761 LSPs between a pair of LSRs, when: 763 (1) A single TE LSP satisfying the required set of constraints 764 cannot be found, in which case it may require load splitting. 766 (2) Multiple TE paths may be required to limit the impact of a 767 network element failure to a portion of the traffic. As an 768 example, two VoIP gateways may load balance the traffic among 769 a set of inter-AS TE LSPs. 771 (3) Path protection (e.g. 1:1 or 1:N) as discussed in 772 [MPLS-Recov]. 774 In the examples above, being able to set up diversely routed TE LSPs 775 becomes a requirement for inter-AS TE. 777 The solution SHOULD be able to set up a set of link/SRLG/Node 778 diversely routed inter-AS TE LSPs. 780 5.1.5. Re-optimization 782 Once an inter-AS TE LSP has been established and should there be any 783 resource or other changes inside anyone of transiting ASes, the 784 solution MUST be able to re-optimize the LSP accordingly and 785 non-disruptively, either upon expiration of a configurable timer or 786 triggered by a network event or a manual request at the TE tunnel 787 Head-end. 789 The solution SHOULD provide an option for the Head-End LSRs to 790 control if re-optimizing or not should there exist a more optimal 791 path in one of the transit ASes along the inter-AS TE LSP path. 793 In the case of an identical set of traversed path, the solution 794 SHOULD provide an option for the Head-End LSRs to control if 795 re-optimizing or not should there exist a more optimal path in one 796 of the transit ASes along the inter-AS TE LSP path. 798 Furthermore, the solution MUST provide the ability to reject 799 re-optimizatization at AS boundaries. 801 5.1.6. Fast Recovery support using MPLS TE Fast Reroute 803 There are in general two or more inter-AS links between multiple 804 pair of ASBRs for redundancy. The topological density between ASes 805 in a SP network with multi-ASes is generally much higher. In the 806 event of an inter-AS link failure, rapid local protection SHOULD 807 also be made available and interoperate with current intra-AS MPLS 808 TE fast re-route mechanism from [TE-FRR]. 810 The traffic routed onto an inter-AS TE tunnel SHOULD also be fast 811 protected against any node failure where the node could be internal 812 to an AS or at the AS boundary. 814 5.1.7. DS-TE Support 816 The proposed inter-AS MPLS TE solution SHOULD also satisfy core 817 requirements documented in [DS-TE] and interoperate seamlessly with 818 current intra-AS MPLS DS-TE mechanism [DSTE-PROT]. 820 It is worth pointing out that the compatibility clause in section 821 4.1 of [DS-TE] SHOULD also be faithfully applied in the development 822 of the solutions. 824 5.1.8. Scalability and Hierarchical LSP Support 826 The proposed solution(s) MUST have minimum impact on the network 827 scalability from both intra and inter-AS perspectives. 829 This requirement applies to all of the following: 831 - IGP (impact in terms of IGP flooding, CSPF, etc.). 832 - BGP (impact in terms of additional information carried within 833 BGP, number of routes, flaps, overload events, etc.). 834 - RSVP TE (message rate, number of retained states, ,etc.). 836 It is also conceivable that there would potentially be scalability 837 issues as the number of required inter-AS MPLS TE tunnels increases. 838 In order to reduce the number of tunnel states to be maintained by 839 each 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(s). One such mechanism, for example is 842 described in [MPLS-LSPHIE]. 844 5.1.9. Mapping of traffic onto 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 5.1.11. Extensibility 932 The solution(s) MUST allow extensions as both inter-AS MPLS TE and 933 current intra-AS MPLS TE specifications evolve. 935 5.1.12. Complexity and Risks 937 The proposed solution(s) SHOULD not introduce unnecessary complexity 938 to the current operating network to such a degree that it would 939 affect the stability and diminish the benefits of deploying such a 940 solution over SP networks. 942 5.1.13. Backward Compatibility 944 The deployment of inter-AS MPLS TE SHOULD not have impact on 945 existing BGP-based traffic engineering or MPLS TE mechanisms to 946 allow for a smooth migration or co-existence. 948 5.2. Requirements for Inter-AS MPLS TE across Multiple SP 949 Administrative Domains. 951 The requirements for inter-AS MPLS TE across multiple SP admin 952 domains SHOULD include all requirements discussed in section 5.1 953 above in addition to what are presented in this section here. 955 Please note that the SP with multi-AS networks may choose not to 956 turn on the features discussed in the following two sections when 957 building TE tunnels across ASes in its own domain. 959 5.2.1. Confidentiality 961 Since an inter-AS TE LSP may span multiple ASes belonging to 962 different SPs, the solution MIGHT allow to "hide" the set of hops 963 used by the TE LSP within an AS as illustrated in the following 964 example: 966 [ ASBR1-----ASBR2 ] 967 [ ] [ ] 968 [ A ] [ B ] 969 [ AS1 ] [ AS2 ] 970 [ SP1 ]-----[ SP2 ] 971 [ ] [ ] 973 Suppose there is an inter-AS TE LSP from A (within AS1 of SP1) to B 974 (within AS2 of SP2). When computing an inter-AS TE LSP path, the 975 set of hops within AS2 might be hidden to AS1. In this case, the 976 solution will allow A to learn that the more optimal TE LSP path to 977 B that complies with the set of constraints traverses ASBR2 without 978 a detailed knowledge of the lists of the hops used within AS2. 980 Optionally, the TE LSP path cost within AS2 could be provided to A, 981 via for example PCC-PCS signaling [PATH-COMP], such that A (PCC) 982 could use this information to compute an optimal path, even if the 983 computed path is not provided by AS2. 985 In addition, the management requirements discussed in section 5.1.10 986 above, when used across different SP admin domains, SHOULD include 987 similar confidentiality requirements discussed here in terms of 988 "hiding" intermediate hops or interface address and/ or labels in 989 the transiting or peering SPs. 991 5.2.2. Policy Control 993 In some cases, policy control might be necessary at the AS 994 boundaries, namely ingress policy controls enabling SPs to enforce 995 the inter-AS policies per interconnect agreements or modify some 996 requested parameters conveyed by incoming inter-AS MPLS TE signaling 997 requests. 999 It is worth noting that such policy control mechanism may also be 1000 used between ASes within a SP. 1002 This section only discusses the elements that may be used to form a 1003 set of ingress control policies. However, how exactly SPs establish 1004 bilateral or multilateral agreements upon which the control policies 1005 can be built are beyond the scope of this document. 1007 5.2.2.1. Inter-AS TE Agreement Enforcement Polices 1009 The following provides a set of TE-LSP parameters in the inter-AS TE 1010 requests(RSVP Path Message) that could be enforced at the AS 1011 boundaries: 1013 - RSVP-TE session attributes: affinities and preemption 1014 priorities 1015 - Per AS or SP bandwidth admission control to ensure that RSVP-TE 1016 messages do not request for bandwidth resources over their 1017 allocation. 1019 - Request origins which can be represented by HE tunnel ending IP 1020 address, originating AS#, neighbor AS#, neighbor ASBR interface 1021 IP address, etc. 1022 - DS-TE TE-Class . 1023 - FRR attribute: local protection desired bit, node protection 1024 desired bit and bandwidth protection desired bit carried in the 1025 SESSION 1026 - ATTRIBUTE or the FAST-REROUTE objects in the RSVP Path message 1027 as defined in [TE-FRR]. 1028 - Optimization allowed or not. 1030 In some cases, a TE policy server could also be used for the 1031 enforcement of inter-AS TE policies. This requirement could allow 1032 SPs to make the inter-AS TE policies scale better. 1034 The signaling of a non policy compliant request SHOULD trigger the 1035 generation of a RSVP Path Error message by the policy enforcing 1036 node towards the Head-end LSR, indicating the cause. The 1037 Head-end LSR SHOULD take appropriate actions, such as re-route, upon 1038 receipt of such a message. 1040 5.2.2.2. Inter-AS TE Rewrite Policies 1042 In some situations, SPs may need to rewrite some attributes of the 1043 incoming inter-AS TE signaling requests due to for example, a lack 1044 of resources for a particular TE-Class, non compliant preemption, 1045 upon mutual agreements. The following lists a set of parameters 1046 that can potentially be rewritten at the AS boundaries: 1048 - RSVP-TE session attributes: affinities and preemption 1049 priorities 1050 - DS-TE TE-Class . 1051 - ERO expansion requests 1053 Simimarly, the re-writing node SHOULD generate a RSVP Path Error 1054 Message towards the Head-end LSR indicating the cause in terms 1055 of types of changes made so as to maintain the end-to-end integrity 1056 of inter-AS TE LSP. 1058 5.2.2.3 Inter-AS Traffic Policing 1060 The proposed solution SHOULD also provide a set of policing 1061 mechanisms which could be configured on the inter-AS links, 1062 to ensure that traffic routed through the tunnel does not exceed 1063 the bandwidth negotiated during LSP signaling. 1065 For example, an ingress policer could be configured to enforce 1066 the traffic contract on the mutually agreed resource requirements 1067 of the established inter-AS TE LSP (i.e. RSVP bandwidth) on the 1068 interface to which the inter-AS link is connected. 1070 6. Evaluation Criteria 1072 There may be multiple solutions to satisfy the requirements for 1073 Inter-AS MPLS TE presented in previous sections. 1075 This section provides general guidelines, which could be applied in 1076 the selection of an optimum solution. 1078 6.1. Detailed Requirement Satisfactions 1080 The proposed solution SHOULD include at least all of the 1081 Application Scenarios presented in section 4 above. It MUST meet all 1082 the requirements described in section 5 each time a MUST is 1083 specified. 1085 If a solution can fulfill just a subset of those requirements in 1086 section 5, then it MUST be explicitly documented 1088 6.2. 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 7. Security Considerations 1101 The proposed solution(s) MUST address security issues across 1102 multiple SP administrative domains. Although inter-AS MPLS TE is 1103 not expected to add specific security extensions beyond those of 1104 current intra-AS TE, greater considerations MUST be given in terms 1105 of how to establish a trusted model across AS boundaries. SPs 1106 SHOULD have a means to authenticating, such as using RSVP INTEGRITY 1107 object, allowing and possibly denying inter-AS signaling requests 1108 and SHOULD be protected from DoS attacks. 1110 8. Acknowledgement 1112 We would like to thank Yuichi Ikejiri, David Allan, Kurt Erik 1113 Lindqvist, Dave McDysan, Christian Jacquenet, Kireeti Kompella, 1114 Ed Kern, Jim Boyle, Thomas Nadeauor and Yakov Rekhter for their 1115 suggestions and helpful comments during the discussions of this 1116 draft. 1118 9. Editor's Addresses 1120 Raymond Zhang 1121 Infonet Services Corporation 1122 2160 E. Grand Ave. 1123 El Segundo, CA 90025 1124 USA 1125 Email: raymond_zhang@infonet.com 1127 JP Vasseur 1128 CISCO Systems, Inc. 1129 300 Beaver Brook Road 1130 Boxborough , MA - 01719 1131 USA 1132 Email: jpv@cisco.com 1134 10. Normative References 1136 [TE-REQ], Awduche et. al., "Requirements for Traffic Engineering 1137 over MPLS", RFC2702, September 1999. 1139 [TE-RSVP], Awduche et. al., "RSVP-TE: Extensions to RSVP for LSP 1140 Tunnels", RFC 3209, December 2001 1142 [GMPLS-ROUT], Kompella, et. al., "RGeneralized Multi-Protocol Label 1143 Switching (GMPLS) Signaling Resource ReserVation Protocol-Traffic 1144 Engineering (RSVP-TE) Extensions, RFC 3473, January 2003. 1146 [BGP], Rekhter, et. al., "A Border Gateway Protocol 4 (BGP-4)", 1147 RFC 1771, March 1995 1149 [LSPPING], Kompella, et.. al.," Detecting Data Plane Liveliness in 1150 MPLS", Internet Draft , June 2003, 1151 (Work in Progress) 1153 [MPLS-TTL], Agarwal, et. al., "Time to Live (TTL) Processing in MPLS 1154 Networks", RFC 3443, January, 2003 1156 [DS-TE], Le Faucheur, et. al., ''Requirements for support of 1157 DiffServ-aware MPLS Traffic Engineering'', RFC 3564, July, 2003 1159 [DSTE-PROT], Le Faucheur, et. al., "Protocol extensions for support 1160 of Diff-Serv-aware MPLS Traffic Engineering", draft-ietf-tewg-diff 1161 -te-proto-05.txt, September, 2003 (Work in Progress). 1163 [TE-FRR], Pan, et. al., "Fast Reroute Techniques in RSVP-TE", 1164 draft-ietf-mpls-rsvp-lsp-fastreroute-03.txt, June 2003 1165 (Work in Progress). 1167 [ISIS-TE], Smit, Li, "IS-IS extensions for Traffic Engineering", 1168 draft-ietf-isis-traffic-05.txt, August, 2003 (Work in Progress). 1170 [OSPF-TE] Katz, Yeung, "Traffic Engineering Extensions to OSPF", 1171 draft-ietf-ospf-ospfv3-traffic-01.txt, June, 2001 1172 (Work in Progress). 1174 [PATH-COMP], Vasseur, et. al., ''RSVP Path computation request and 1175 reply messages'', draft-vasseur-mpls-computation-rsvp-03.txt, June 1176 2002. (Work in Progress) 1178 [OSPF-TE-CAP], Vasseur, Psenak. "OSPF TE TLV capabilities", 1179 draft-vasseur-mpls-ospf-te-cap-00.txt, October 2002. 1180 (Work in Progress) 1182 [MPLS-LSPHIE] Kompella, Rekhter, "LSP Hierarchy with Generalized 1183 MPLS TE", draft-ietf-mpls-lsp-hierarchy-08.txt , March 2002. 1184 (work in progress) 1186 [MPLS-Recov], Sharma V., et al, "Framework for Multi-Protocol Label 1187 Switching (MPLS)-based Recovery", RFC 3469, Feb, 2003 1189 [BGP-Label], Rekhter and Rosen, "Carrying Label Information in 1190 BGP-4", RFC 3107, May 2001 1192 [INTER-AS-TE], Vasseur and Zhang, "Inter-AS MPLS Traffic 1193 Engineering", draft-vasseur-inter-as-te-01.txt, June, 2003 (work 1194 in progress). 1196 [EXCLUDE-ROUTE], Farrel, et. al., "draft-ietf-ccamp-rsvp-te-exclude 1197 -route-00.txt", June 2003 (work in progress). 1199 11. Informative References 1201 [MPLS-ARCH], Rosen, et. al., "Multiprotocol Label Switching 1202 Architecture", RFC 3031, January 2001 1204 [BGP-MPLSVPN], Rosen, et. al., "BGP/MPLSVPN", draft-ietf-l3vpn 1205 -rfc2547bis-01.txt, July 2002 (work in progress). 1207 [DIFF_ARCH], Blake, et. al., "An Architecture for Differentiated 1208 Services", RFC 2475, December 1998. 1210 [DIFF_AF], Heinanen,et. al., "Assured Forwarding PHB Group", RFC 1211 2597, June 1999. 1213 [DIFF_EF], Davie, et. al., "An Expedited Forwarding PHB (Per-Hop 1214 Behavior)", RFC 3246, March 2002. 1216 [MPLS-Diff], Le Faucheur, et. al., "MPLS Support of Differentiated 1217 Services", RFC 3270, May 2002 1219 [TE-OVW], Awduche, et. al., "Overview and Principles of Internet 1220 Traffic Engineering", RFC 3272,May 2002 1222 [PSTE], Li, et. al., "A Provider Architecture for Differentiated 1223 Services and Traffic Engineering", RFC 2430, October 1998 1225 [TE-APP], Boyle, et. al., "Applicability Statement of Traffic 1226 Engineering", RFC 3346, August 2002. 1228 [TE-SURVIV], Lai, et. al., "Network Hierachy and Multilayer 1229 Suvivability", RFC 3386, November, 2002. 1231 12. Full Copyright Statement 1233 Copyright (C) The Internet Society (2003). All Rights Reserved. 1235 This document and translations of it may be copied and furnished to 1236 others, and derivative works that comment on or otherwise explain it 1237 or assist in its implementation may be prepared, copied, published 1238 and distributed, in whole or in part, without restriction of any 1239 kind, provided that the above copyright notice and this paragraph 1240 are included on all such copies and derivative works. However, this 1241 document itself may not be modified in any way, such as by removing 1242 the copyright notice or references to the Internet Society or other 1243 Internet organizations, except as needed for the purpose of 1244 developing Internet standards in which case the procedures for 1245 copyrights defined in the Internet Standards process MUST be 1246 followed, or as required to translate it into languages other than 1247 English. 1249 The limited permissions granted above are perpetual and will not be 1250 revoked by the Internet Society or its successors or assigns. 1252 This document and the information contained herein is provided on an 1253 "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING 1254 TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING 1255 BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION 1256 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF 1257 MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 1259 Appendix A. Brief Description of BGP based Inter-AS Traffic 1260 Engineering 1262 In today's Service Provider (SP) network, BGP is deployed to meet 1263 two different sets of requirements: 1265 - Establishing a scalable exterior routing plane separating from 1266 data forwarding plane within SP's administrative domain 1267 - Exchanging network reachability information with different BGP 1268 autonomous systems (ASes) that could belong to a different SP 1269 or simply, a different AS within a SP network. 1271 Over connections across the AS boundaries, traffic engineering may 1272 also be accomplished via a set of BGP capabilities by appropriately 1273 enforcing BGP-based inter-AS routing policies. The current 1274 BGP-based inter-AS traffic engineering practices may be summarized 1275 as follows: 1277 - "Closest exit" routing where egress traffic from one SP to 1278 another follows the path defined by the lowest IGP or intra-AS 1279 MPLS TE tunnel metrics of the BGP next-HOP of exterior routes 1280 learned from other AS over the inter-AS links 1281 - "BGP path attribute" based routing selection mechanism where 1282 the egress traffic path is determined by interconnect (peering 1283 or transit) policies based upon one or a combination of BGP 1284 path attributes, like AS_PATH, MULTI_EXIT_DISC (MED), and 1285 Local_Pref. 1287 SPs have often faced a number of un-deterministic factors in their 1288 practices of inter-AS traffic engineering employing the methods 1289 mentioned above: 1291 - Sub-optimum traffic distribution across inter-AS links 1292 - Un-deterministic traffic condition changes due to uncoordinated 1293 IGP routing policies or topology changes within other AS and 1294 uncoordinated BGP routing policy changes (MED or as-prepend, 1295 etc.) 1297 In addition, to achieve some degrees of granularity, SPs may choose 1298 to enforce BGP inter-AS policies that are specific to one or a set 1299 of inter-AS links for ingress traffic destined to certain PoPs or 1300 regions within SP's network from another AS by tagging certain sets 1301 of routes with a specific attribute when announcing to another AS. 1302 This of course goes under the assumption that the other AS permits 1303 automated egress policy by matching the predefined attribute from 1304 incoming routes.