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(See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (November 5, 2007) is 6010 days in the past. Is this intentional? Checking references for intended status: Informational ---------------------------------------------------------------------------- No issues found here. Summary: 2 errors (**), 0 flaws (~~), 1 warning (==), 7 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group K. Kumaki, Ed. 3 Internet Draft KDDI Corporation 4 Intended Status: Informational 5 Created: November 5, 2007 6 Expires: May 5, 2008 8 Interworking Requirements to Support operation of MPLS-TE over GMPLS 9 Networks 11 draft-ietf-ccamp-mpls-gmpls-interwork-reqts-03.txt 13 Status of this Memo 15 By submitting this Internet-Draft, each author represents that any 16 applicable patent or other IPR claims of which he or she is aware 17 have been or will be disclosed, and any of which he or she becomes 18 aware will be disclosed, in accordance with Section 6 of BCP 79. 20 Internet-Drafts are working documents of the Internet Engineering 21 Task Force (IETF), its areas, and its working groups. Note that 22 other groups may also distribute working documents as 23 Internet-Drafts. 25 Internet-Drafts are draft documents valid for a maximum of six months 26 and may be updated, replaced, or obsoleted by other documents at any 27 time. It is inappropriate to use Internet-Drafts as reference 28 material or to cite them other than as "work in progress." 30 The list of current Internet-Drafts can be accessed at 31 http://www.ietf.org/ietf/1id-abstracts.txt 33 The list of Internet-Draft Shadow Directories can be accessed at 34 http://www.ietf.org/shadow.html. 36 Abstract 38 Operation of a Multiprotocol Label Switching (MPLS) traffic 39 engineering (TE) network as a client network to a Generalized MPLS 40 (GMPLS) network has enhanced operational capabilities compared to 41 those provided by a co-existent protocol model (i.e., operation of 42 MPLS-TE over an independently managed transport layer). 44 The GMPLS network may be a packet or a non-packet network, and may 45 itself be a multi-layer network supporting both packet and non-packet 46 technologies. A MPLS-TE Label Switched Path (LSP) originates and 47 terminates on an MPLS Label Switching Router (LSR). The GMPLS network 48 provides transparent transport for the end-to-end MPLS-TE LSP. 50 This document describes a framework and Service Provider requirements 51 for operating MPLS-TE networks over GMPLS networks. 53 Table of Contents 55 1. Introduction...................................................2 56 1.1 Terminology................................................3 57 2. Reference model................................................4 58 3. Detailed Requirements..........................................4 59 3.1 End-to-End Signaling.......................................5 60 3.2 Triggered Establishment of GMPLS LSPs......................5 61 3.3 Diverse Paths for End-to-End MPLS-TE LSPs..................5 62 3.4 Advertisement of MPLS-TE Information via the GMPLS Network.5 63 3.5 Selective Advertisement of MPLS-TE Information via a Border 64 Node...........................................................5 65 3.6 Interworking of MPLS-TE and GMPLS Protection...............6 66 3.7 Independent Failure Recovery and Reoptimization............6 67 3.8 Complexity and Risks.......................................6 68 3.9 Scalability Considerations.................................6 69 3.10 Performance Considerations................................7 70 3.11 Management Considerations.................................7 71 4. Security Considerations........................................7 72 5. Recommended Solution Architecture..............................8 73 5.1 Use of Contiguous, Hierarchical, and Stitched LSPs.........9 74 5.2 MPLS-TE Control Plane Connectivity.........................9 75 5.3 Fast Reroute Protection....................................9 76 5.4 GMPLS LSP Advertisement...................................10 77 5.5 GMPLS Deployment Considerations...........................10 78 6. IANA Considerations...........................................10 79 7. Acknowledgments...............................................10 80 8. References....................................................10 81 8.1 Normative References......................................10 82 8.2 Informative References....................................11 83 9. Author's Address..............................................11 84 10. Contributors' Addresses......................................12 85 11. Intellectual Property Statement..............................12 87 1. Introduction 89 Multiprotocol Label Switching traffic engineering (MPLS-TE) networks 90 are often deployed over transport networks such that the transport 91 networks provide connectivity between the Label Switching Routers 92 (LSRs) in the MPLS-TE network. Increasingly, these transport networks 93 are operated using a Generalized Multiprotocol Label Switching 94 (GMPLS) control plane, and label Switched Paths (LSPs) in the GMPLS 95 network provide connectivity as virtual data links advertised as TE 96 links in the MPLS-TE network. 98 GMPLS protocols were developed as extensions to MPLS-TE protocols. 99 MPLS-TE is limited to the control of packet switching networks, but 100 GMPLS can also control technologies at layers one and two. 102 The GMPLS network may be managed by an operator as a separate network 103 (as it may have been when it was under management plane control 104 before the use of GMPLS as a control plane), but optimizations of 105 management and operation may be achieved by coordinating the use of 106 the MPLS-TE and GMPLS networks and operating the two networks with a 107 close client/server relationship. 109 GMPLS LSP setup may triggered by the signaling of MPLS-TE LSPs in the 110 MPLS-TE network so that the GMPLS network is reactive to the needs of 111 the MPLS-TE network. The triggering process can be under the control 112 of operator policies without needing direct intervention by an 113 operator. 115 The client/server configuration just described can also apply in 116 migration scenarios for MPLS-TE packet switching networks that are 117 being migrated to be under GMPLS control. [MIGRATE] describes a 118 migration scenario called the Island Model. In this scenario, groups 119 of nodes (islands) are migrated from the MPLS-TE protocols to the 120 GMPLS protocols and operate entirely surrounded by MPLS-TE nodes (the 121 sea). This scenario can be effectively managed as a client/server 122 network relationship using the framework described in this document. 124 In order to correctly manage the dynamic interaction between the MPLS 125 and GMPLS networks, it is necessary to understand the operational 126 requirements and the control that the operator can impose. Although 127 this problem is very similar to the multi-layer networks described in 128 [MLN], it must be noted that those networks operate GMPLS protocols 129 in both the client and server networks which facilitates smoother 130 interworking. Where the client network uses MPLS-TE protocols over 131 the GMPLS server network there is a need to study the interworking of 132 the two protocol sets. 134 This document examines the protocol requirements for protocol 135 interworking to operate an MPLS-TE network as a client network over a 136 GMPLS server network, and provides a framework for such operations. 138 1.1 Terminology 140 Although this Informational document is not a protocol specification, 141 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 142 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 143 document are to be interpreted as described in [RFC2119] for clarity 144 of exposure of the requirements. 146 2. Reference model 148 The reference model used in this document is shown in Figure 1. It 149 can easily be seen that the interworking between MPLS-TE and GMPLS 150 protocols must occur on a node and not on a link. Nodes on the 151 interface between the MPLS-TE and GMPLS networks must be responsible 152 for handling both protocol sets and for providing any protocol 153 interworking that is required. We call these nodes Border Routers. 155 -------------- ------------------------- -------------- 156 | MPLS Client | | GMPLS Server Network | | MPLS Client | 157 | Network | | | | Network | 158 | | | | | | 159 | ---- --+--+-- ----- ----- --+--+-- ---- | 160 | | | | | | | | | | | | | | 161 | |MPLS|_| Border |__|GMPLS|_|GMPLS|__| Border |_|MPLS| | 162 | |LSR | | Router | | LSR | | LSR | | Router | |LSR | | 163 | | | | | | | | | | | | | | 164 | ---- --+--+-- ----- ----- --+--+-- ---- | 165 | | | | | | 166 | | | | | | 167 -------------- ------------------------- -------------- 169 | | GMPLS LSP | | 170 | |<------------------------->| | 171 | | 172 |<--------------------------------------------->| 173 End-to-End MPLS-TE LSP 175 Figure 1. Reference model of MPLS-TE/GMPLS interworking 177 MPLS-TE network connectivity is provided through a GMPLS LSP which is 178 created between Border Routers. End-to-end connectivity between MPLS 179 LSRs in the client MPLS-TE networks is provided by an MPLS-TE LSP 180 that is carried across the MPLS-TE network by the GMPLS LSP using 181 hierarchical LSP techniques [RFC4206], LSP stitching segments 182 [STITCH], or a contiguous LSP. LSP stitching segments and contiguous 183 LSPs are only available where the GMPLS network is a packet switching 184 network. 186 3. Detailed Requirements 188 This section describes detailed requirements for MPLS-TE/GMPLS 189 interworking in support of the reference model shown in Figure 1. 191 3.1 End-to-End Signaling 193 The solution MUST be able to preserve MPLS signaling information 194 signaled within the MPLS-TE client network at the start of the MPLS- 195 TE LSP, and deliver it on the other side of the GMPLS server network 196 for use within the MPLS-TE client network at the end of the MPLS-TE 197 LSP. This may require protocol mapping (and re-mapping), protocol 198 tunneling, or the use of remote protocol adjacencies. 200 3.2 Triggered Establishment of GMPLS LSPs 202 The solution MUST provide the ability to establish end-to-end MPLS- 203 TE LSPs over a GMPLS server network. It SHOULD be possible for GMPLS 204 LSPs across the core network to be set up between Border Routers 205 triggered by the signaling of MPLS-TE LSPs in the client network, and 206 in this case, policy controls MUST be made available at the border 207 routers so that the operator of the GMPLS network can manage how core 208 network resources are utilized. GMPLS LSPs MAY also be pre- 209 established as the result of management plane control. 211 3.3 Diverse Paths for End-to-End MPLS-TE LSPs 213 The solution SHOULD provide the ability to establish end-to-end MPLS- 214 TE LSPs having diverse paths for protection of the LSP traffic. This 215 means that MPLS-TE LSPs SHOULD be kept diverse both within the client 216 MPLS-TE network and as they cross the server GMPLS network. This 217 means that there SHOULD be a mechanism to request the provision of 218 diverse GMPLS LSPs between a pair of Border Routers to provide 219 protection of the GMPLS span, but also that there SHOULD be a way to 220 keep GMPLS LSPs between different Border Routers disjoint. 222 3.4 Advertisement of MPLS-TE Information via the GMPLS Network 224 The solution SHOULD provide the ability to exchange advertisements of 225 TE information between MPLS-TE client networks across the GMPLS 226 server network. 228 The advertisement of TE information from within an MPLS-TE client 229 network to all LSRs in the client network enables a head end LSR to 230 compute an optimal path for an LSP to a tail end LSR that is reached 231 over the GMPLS server network. 233 Where there is more than one client MPLS-TE network, the TE 234 information from separate MPLS-TE networks MUST be kept private, 235 confidential and secure. 237 3.5 Selective Advertisement of MPLS-TE Information via a Border Node 238 The solution SHOULD provide the ability to distribute TE reachability 239 information from the GMPLS server network to MPLS-TE networks 240 selectively. This information is useful for the LSRs in the MPLS-TE 241 networks to compute paths that cross the GMPLS server network and to 242 select the correct Border Routers to provide connectivity. 244 The solution MUST NOT distribute TE information from within a non-PSC 245 (Packet Switch Capable) GMPLS server network to any client MPLS-TE 246 network as that information may cause confusion and selection of 247 inappropriate paths. 249 3.6 Interworking of MPLS-TE and GMPLS Protection 251 If an MPLS-TE LSP is protected using MPLS Fast Reroute (FRR) 252 [RFC4090], then similar protection MUST be provided over the GMPLS 253 island. Operator and policy controls SHOULD be made available at the 254 Border Router to determine how suitable protection is provided in the 255 GMPLS island. 257 3.7 Independent Failure Recovery and Reoptimization 259 The solution SHOULD provide failure recovery and reoptimization in 260 the GMPLS server network without impacting the MPLS-TE client network 261 and vice versa. That is, it SHOULD be possible to recover from a 262 fault within the GMPLS island or to reoptimize the path across the 263 GMPLS island without requiring signaling activity within the MPLS-TE 264 client network. Similarly, it SHOULD be possible to perform recovery 265 or reoptimization within the MPLS-TE client network without requiring 266 signaling activity within the GMPLS server networks. 268 If a failure in the GMPLS server network can not be repaired 269 transparently, some kind of notification of the failure SHOULD be 270 transmitted to MPLS-TE network. 272 3.8 Complexity and Risks 274 The solution SHOULD NOT introduce unnecessary complexity to the 275 current operating network to such a degree that it would affect the 276 stability and diminish the benefits of deploying such a solution in 277 service provider networks. 279 3.9 Scalability Considerations 281 The solution MUST scale well with consideration to at least the 282 following metrics. 284 - The number of GMPLS-capable nodes (i.e., the size of the GMPLS 285 server network). 287 - The number of MPLS-TE-capable nodes (i.e., the size of the MPLS-TE 288 client network). 289 - The number of MPLS-TE client networks. 290 - The number of GMPLS LSPs. 291 - The number of MPLS-TE LSPs. 293 3.10 Performance Considerations 295 The solution SHOULD be evaluated with regard to the following 296 criteria. 298 - Failure and restoration time. 299 - Impact and scalability of the control plane due to added 300 overheads. 301 - Impact and scalability of the data/forwarding plane due to added 302 overheads. 304 3.11 Management Considerations 306 Manageability of the deployment of an MPLS-TE client network over 307 GMPLS server network MUST addresses the following considerations. 309 - Need for coordination of MIB modules used for control plane 310 management and monitoring in the client and server networks. 311 - Need for diagnostic tools that can discover and isolate faults 312 across the border between the MPLS-TE client and GMPLS server 313 networks. 315 4. Security Considerations 317 Border routers in the model described in this document are present on 318 administrative domain boundaries. That is, the administrative 319 boundary does not lie on a link as it might in the inter-Autonomous 320 System case seen in IP networks. Thus, many security concerns for the 321 inter-domain exchange of control plane messages do not arise in this 322 model - the border router participates fully in both the MPLS and the 323 GMPLS network and must participate in the security procedures of both 324 networks. Security considerations for MPLS-TE and GMPLS protocols are 325 discussed in [SECURITY]. 327 However, policy considerations at the border routers are very 328 important and may be considered to form part of the security of the 329 networks. In particular, the server network (the GMPLS network) may 330 wish to protect itself from behavior in the client network (such as 331 frequent demands to set up and tear down server LSPs) by appropriate 332 policies implemented at the border routers. It should be observed 333 that, because the border routers form part of both networks, they are 334 trusted in both networks, and policies configured (whether locally or 335 centrally) for use by a border router are expected to be observed. 337 Nevertheless, authentication and access controls for operators will 338 be particularly important at border routers. Operators of the client 339 MPLS-TE network MUST NOT be allowed to configure the server GMPLS 340 network (including setting server network policies), and operators of 341 the server GMPLS network MUST NOT be able configure the client MPLS- 342 TE network. Obviously, it SHOULD be possible to grant an operator 343 privileges in both networks. It may also be desirable to give 344 operators of one network access to (for example) status information 345 about the other network. 347 Mechanisms for authenticating operators and providing access controls 348 do not form part of the responsibilities of the GMPLS protocol set, 349 and will depend on the management plane protocols and techniques 350 implemented. 352 5. Recommended Solution Architecture 354 The recommended solution architecture to meet the requirements set 355 out in Section 3 is known as the Border Peer Model. This architecture 356 is a variant of the Augmented Model described in [RFC3945]. The 357 remainder of this document presents an overview of this architecture. 359 In the Augmented Model, routing information from the lower layer 360 (server) network is filtered at the interface to the higher layer 361 (client) network and a subset of the information is distributed 362 within the higher layer network. 364 In the Border Peer Model, the interface between the client and server 365 networks is the Border Router. This router has visibility of the 366 routing information in the server network yet also participates as a 367 peer in the client network. Thus the Border Router has full 368 visibility into both networks. However, the Border Router does not 369 distribute server routing information into the client network, nor 370 does it distribute client routing information into the server network. 372 The Border Peer Model may also be contrasted with the Overlay Model 373 [RFC3945]. In this model there is a protocol request/response 374 interface (the user network interface - UNI) between the client and 375 server networks. [RFC4208] shows how this interface may be supported 376 by GMPLS protocols operated between client edge and server edge 377 routers while retaining the routing information within the server 378 network. That is, in the Overlay Model there is no exchange of 379 routing or reachability information between client and server 380 networks, and no network element has visibility into both client and 381 server networks. The Border Peer Model can be viewed as placing the 382 UNI within the Border Router thus giving the Border Router peer 383 capabilities in both the client and server network. 385 5.1 Use of Contiguous, Hierarchical, and Stitched LSPs 387 All three LSP types MAY be supported in the Border Peer Model, but 388 contiguous LSPs are the hardest to support because they require 389 protocol mapping between the MPLS-TE client network and the GMPLS 390 server network. Such protocol mapping can be achieved currently since 391 MPLS-TE signaling protocols are a subset of GMPLS, but this mechanism 392 is not future-proofed. 394 Contiguous and stitched LSPs can only be supported where the GMPLS 395 server network has the same switching type (that is, packet 396 switching) as the MPLS-TE network. Requirements for independent 397 failure recovery within the GMPLS island require the use of loose 398 path reoptimization techniques [RFC4736] and end-to-end make-before- 399 break [RFC3209] which will not provide rapid recovery. 401 For these reasons, the use of hierarchical LSPs across the server 402 network is RECOMMENDED for the Border Peer Model, but see the 403 discussion of Fast Reroute protection in Section 5.3. 405 5.2 MPLS-TE Control Plane Connectivity 407 Control plane connectivity between MPLS-TE LSRs connected by a GMPLS 408 island in the Border Peer Model MAY be provided by the control 409 channels of the GMPLS network. If this is done, a tunneling mechanism 410 (such as GRE [RFC2784]) SHOULD be used to ensure that MPLS-TE 411 information is not consumed by the GMPLS LSRs. But care is required 412 to avoid swamping the control plane of the GMPLS network with MPLS-TE 413 control plane (particularly routing) messages. 415 In order to ensure scalability, control plane messages for the MPLS- 416 TE client network MAY be carried between Border Routers in a single 417 hop MPLS-TE LSP routed through the data plane of the GMPLS server 418 network. 420 5.3 Fast Reroute Protection 422 If the GMPLS network is packet switching, Fast Reroute protection can 423 be offered on all hops of a contiguous LSP. If the GMPLS network is 424 packet switching then all hops of a hierarchical GMPLS LSP or GMPLS 425 stitching segment can be protected using Fast Reroute. If the end-to- 426 end MPLS-TE LSP requests Fast Reroute protection, the GMPLS packet 427 switching network SHOULD provide such protection. 429 However, note that it is not possible to provide FRR node protection 430 of the upstream Border Router without careful consideration of 431 available paths, and protection of the downstream Border Router is 432 not possible where hierarchical LSPs or stitching segments are used. 434 Note further that Fast Reroute is not available in non-packet 435 technologies. However, other protection techniques are supported by 436 GMPLS for non-packet networks and are likely to provide similar 437 levels of protection. 439 The limitations of FRR need careful consideration by the operator and 440 may lead to the decision to provide end-to-end protection for the 441 MPLS-TE LSP. 443 5.4 GMPLS LSP Advertisement 445 In the Border Peer Model, the LSPs established by the Border Routers 446 in the GMPLS server network SHOULD be advertised in the MPLS-TE 447 client network as real or virtual links. In case real links are 448 advertised into the MPLS-TE client network, the Border Routers in the 449 MPLS-TE client network MAY establish IGP neighbors. The Border 450 Routers MAY automatically advertise the GMPLS LSPs when establishing 451 them. 453 5.5 GMPLS Deployment Considerations 455 The Border Peer Model does not require the existing MPLS-TE client 456 network to be GMPLS aware and does not affect on the operation and 457 management of the existing MPLS-TE client network. Only border 458 routers need to be upgraded with the GMPLS functionality. In this 459 fashion, the Border Peer Model renders itself for incremental 460 deployment of the GMPLS server network, without requiring 461 reconfiguration of existing areas/ASes, changing operation of IGP and 462 BGP or software upgrade of the existing MPLS-TE client network. 464 6. IANA Considerations 466 This requirements document makes no requests for IANA action. 468 [RFC Editor: please remove this section before publication.] 470 7. Acknowledgments 472 The author would like to express thanks to Raymond Zhang, Adrian 473 Farrel, and Deborah Brungard for their helpful and useful comments 474 and feedback. 476 8. References 478 8.1 Normative References 480 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 481 Requirement Levels", BCP 14, RFC 2119, March 1997. 483 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V. 484 and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP 485 Tunnels", RFC 3209, December 2001. 487 [RFC3945] Mannie, E., "Generalized Multi-Protocol Label Switching 488 (GMPLS) Architecture", RFC3945, October 2004. 490 [RFC4090] Pan, P., Swallow, G. and A. Atlas, "Fast Reroute 491 Extensions to RSVP-TE for LSP Tunnels", RFC 4090, May 2005. 493 [RFC4206] Kompella, K., and Rekhter, Y., "Label Switched Paths (LSP) 494 Hierarchy with Generalized Multi-Protocol Label Switching 495 (GMPLS) Traffic Engineering (TE)", RFC 4206, October 2005. 497 [RFC4208] Swallow, G., et al., "Generalized Multiprotocol Label 498 Switching (GMPLS) User-Network Interface (UNI): Resource 499 ReserVation Protocol-Traffic Engineering (RSVP-TE) Support 500 for the Overlay Model", RFC 4208, October 2005. 502 [STITCH] Ayyangar, A., Vasseur, JP. "Label Switched Path Stitching 503 with Generalized MPLS Traffic Engineering", draft-ietf- 504 ccamp-lsp-stitching, work in progress. 506 8.2 Informative References 508 [RFC2784] Farinacci, D., et al., "Generic Routing Encapsulation 509 (GRE)", RFC 2784, March 2000. 511 [RFC4736] Vasseur, JP., Ikejiri, Y., and Zhang, R., "Reoptimization 512 of Multiprotocol Label Switching (MPLS) Traffic Engineering 513 (TE) loosely routed Label Switch Path (LSP)", RFC4736, 514 November 2006. 516 [MIGRATE] Shiomoto, K., et al., "Framework for MPLS-TE to GMPLS 517 migration", draft-ietf-ccamp-mpls-gmpls-interwork-fmwk, 518 work in progress. 520 [MLN] Shiomoto, K., Papadimitriou, D., Le Roux, J.L., Vigoureux, M., 521 Brungard, D., "Requirements for GMPLS-based multi-region and 522 multi-layer networks (MRN/MLN)", draft-ietf-ccamp-gmpls-mln- 523 reqs, work in progress. 525 [SECURITY] Fang, L., "Security Framework for MPLS and GMPLS Networks", 526 draft-ietf-mpls-mpls-and-gmpls-security-framework, work in 527 progress. 529 9. Author's Address 531 Kenji Kumaki 532 KDDI Corporation 533 Garden Air Tower 534 Iidabashi, Chiyoda-ku, 535 Tokyo 102-8460, JAPAN 536 Email: ke-kumaki@kddi.com 538 10. Contributors' Addresses 540 Tomohiro Otani 541 KDDI R&D Laboratories, Inc. 542 2-1-15 Ohara Kamifukuoka Phone: +81-49-278-7357 543 Saitama, 356-8502. Japan Email: otani@kddilabs.jp 545 Shuichi Okamoto 546 NICT JGN II Tsukuba Reserach Center 547 1-8-1, Otemachi Chiyoda-ku, Phone : +81-3-5200-2117 548 Tokyo, 100-0004, Japan E-mail :okamoto-s@nict.go.jp 550 Kazuhiro Fujihara 551 NTT Communications Corporation 552 Tokyo Opera City Tower 3-20-2 Nishi Shinjuku, Shinjuku-ku 553 Tokyo 163-1421, Japan 554 EMail: kazuhiro.fujihara@ntt.com 556 Yuichi Ikejiri 557 NTT Communications Corporation 558 Tokyo Opera City Tower 3-20-2 Nishi Shinjuku, Shinjuku-ku 559 Tokyo 163-1421, Japan 560 EMail: y.ikejiri@ntt.com 562 11. 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