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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 Network work group Mach Chen 2 Internet Draft Renhai Zhang 3 Expires: March 2008 Huawei Technologies Co.,Ltd 4 Category: Standards Track Xiaodong Duan 5 China Mobile 6 September 6, 2007 8 ISIS Traffic Engineering (ISIS-TE) Extensions in Support of Inter-AS 9 Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS) 10 Traffic Engineering 11 draft-chen-ccamp-isis-interas-te-extension-01.txt 13 Status of this Memo 15 By submitting this Internet-Draft, each author represents that 16 any applicable patent or other IPR claims of which he or she is 17 aware have been or will be disclosed, and any of which he or she 18 becomes aware will be disclosed, in accordance with Section 6 of 19 BCP 79. 21 Internet-Drafts are working documents of the Internet Engineering 22 Task Force (IETF), its areas, and its working groups. Note that other 23 groups may also distribute working documents as 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 This Internet-Draft will expire on March 6, 2008. 38 Abstract 40 This document describes extensions to the ISIS Traffic Engineering 41 (ISIS-TE) mechanisms to support Multiprotocol Label Switching (MPLS) 42 and Generalized MPLS (GMPLS) Traffic Engineering (TE) for multiple 43 Autonomous Systems (ASes). It defines ISIS-TE extensions for the 44 flooding of TE information about inter-AS links which can be used to 45 perform inter-AS TE path computation. 47 Conventions used in this document 49 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 50 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 51 document are to be interpreted as described in RFC-2119 [RFC2119]. 53 Table of Contents 55 1. Introduction.................................................2 56 2. Problem Statement............................................3 57 2.1. A Note on Non-Objectives................................3 58 2.2. Per-Domain Path Determination...........................4 59 2.3. Backward Recursive Path Computation.....................5 60 3. Extensions to ISIS-TE........................................7 61 3.1. Remote AS Number Sub-TLV................................7 62 3.2. Remote ASBR ID Sub-TLV..................................8 63 3.3. Inter-AS Reachability TLV...............................9 64 4. Procedure for Inter-AS TE Links..............................9 65 5. Security Considerations.....................................11 66 6. IANA Considerations.........................................11 67 6.1. Inter-AS Reachability TLV..............................11 68 6.2. Sub-TLVs for the Inter-AS Reachability TLV.............11 69 6.3. Sub-TLVs for the Extended IS Reachability TLV..........12 70 7. Acknowledgments.............................................12 71 8. References..................................................12 72 8.1. Normative References...................................12 73 8.2. Informative References.................................12 74 Authors' Addresses.............................................14 75 Intellectual Property Statement................................14 76 Disclaimer of Validity.........................................15 77 Copyright Statement............................................15 79 1. Introduction 81 [ISIS-TE] defines extensions to the ISIS protocol [ISIS] to support 82 intra-area Traffic Engineering (TE). The extensions provide a way of 83 encoding the TE information for TE-enabled links within the network 84 (TE links) and flooding this information within an area. The Extended 85 IS reachability TLV and Traffic Engineering Router ID TLV, which are 86 defined in [ISIS-TE], are used to carry such TE information. The 87 Extended IS reachability TLV has several nested sub-TLVs which 88 describe the TE attributes for a TE link. 90 [ISIS-TE-V3] and [GMPLS-TE] define similar extensions to ISIS [ISIS] 91 in support of IPv6 and GMPLS traffic engineering respectively. 93 Requirements for establishing Multiprotocol Label Switching (MPLS) TE 94 Label Switched Paths (LSPs) that cross multiple Autonomous Systems 95 (ASes) are described in [INTER-AS-TE-REQ]. As described in [INTER-AS- 96 TE-REQ], a method SHOULD provide the ability to compute a path 97 spanning multiple ASes. So a path computation entity that may be the 98 head-end Label Switching Router (LSR), an AS Border Router (ASBR), or 99 a Path Computation Element (PCE [PCE]) needs to know the TE 100 information not only of the links within an AS, but also of the links 101 that connect to other ASes. 103 In this document, some extensions to ISIS-TE are defined in support 104 of carrying inter-AS TE link information for inter-AS Traffic 105 Engineering. Two new sub-TLVs are added to the Extended IS 106 reachability TLV, and a new TLV, which is referred to as inter-AS 107 reachability TLV, is defined. The extensions are equally applicable 108 to IPv4 and IPv6 as identical extensions to [ISIS-TE] and [ISIS-TE- 109 V3]. The detailed definitions and procedures are discussed in the 110 following sections. 112 2. Problem Statement 114 As described in [INTER-AS-TE-REQ], in the case of establishing an 115 inter-AS TE LSP traversing multiple ASes, the Path message [RFC3209] 116 may include the following elements in the Explicit Route Object (ERO) 117 in order to describe the path of the LSP: 119 - a set of AS numbers as loose hops; and/or 121 - a set of LSRs including ASBRs as loose hops. 123 Two methods for determining inter-AS paths are currently discussed. 124 The per-domain method [PD-PATH] determines the path one domain at a 125 time. The backward recursive method [BRPC] uses cooperation between 126 PCEs to determine an optimum inter-domain path. The sections that 127 follow examine how inter-AS TE link information could be useful in 128 both cases. 130 2.1. A Note on Non-Objectives 132 It is important to note that this document does not make any change 133 to the confidentiality and scaling assumptions surrounding the use of 134 ASes in the Internet. In particular, this document is conformant to 135 the requirements set out in [INTER-AS-TE-REQ]. 137 The following lists of features are explicit exclusions. 139 o There is no attempt to distribute TE information from within one 140 AS to another AS. 142 o There is no mechanism proposed to distribute any form of TE 143 reachability information for destinations outside the AS. 145 o There is no proposed change to the PCE architecture or usage. 147 o TE aggregation is not supported or recommended. 149 o There is no exchange of private information between ASes. 151 o No ISIS adjacencies are formed on the inter-AS link. 153 2.2. Per-Domain Path Determination 155 In the per-domain method of determining an inter-AS path for an MPLS- 156 TE LSP, when an LSR that is an entry-point to an AS receives a PATH 157 message from an upstream AS with an ERO containing a next hop that is 158 an AS number, it needs to find which LSRs (ASBRs) within the local AS 159 are connected to the downstream AS so that it can compute a TE LSP 160 segment across the AS to one of those LSRs and forward the PATH 161 message to the LSR and hence into the next AS. See the figure below 162 for an example: 164 R1------R3----R5-----R7------R9-----R11 165 | | \ | / | 166 | | \ | ---- | 167 | | \ | / | 168 R2------R4----R6 --R8------R10----R12 169 : : 170 <-- AS1 -->:<---- AS2 --->:<--- AS3 ---> 172 Figure 1: Inter-AS Reference Model 174 The figure shows three ASes (AS1, AS2, and AS3) and twelve LSRs (R1 175 through R12). R3 and R4 are ASBRs in AS1. R5, R6, R7, and R8 are 176 ASBRs in AS2. R9 and R10 are ASBRs in AS3. 178 If an inter-AS TE LSP is planned to be established from R1 to R12, 179 the AS sequence is limited as: AS1, AS2, AS3. 181 Suppose that the Path message enters AS2 from R3. The next hop in the 182 ERO shows AS3, and R5 must determine a path segment across AS2 to 183 reach AS3. It has a choice of three exit points from AS2 (R6, R7, and 184 R8) and it needs to know which of these provide TE connectivity to 185 AS3, and whether the TE connectivity (for example, available 186 bandwidth) is adequate for the requested LSP. 188 Alternatively, if the next hop in the ERO is the entry ASBR for AS3 189 (say R9), R5 needs to know which of its exit ASBRs has a TE link that 190 connects to R9. Since there may be multiple exist ASBRs that are 191 connected to R9 (both R7 and R8 in this example), R5 also needs to 192 know the TE properties of the inter-AS TE links so that it can select 193 the correct exit ASBR. 195 Once the path message reaches the exit ASBR, any choice of inter-AS 196 TE link can be made by the ASBR if not already made by entry ASBR 197 that computed the segment. 199 More details can be found in the Section 4.0 of [PD-PATH], which 200 clearly points out why advertising of inter-AS links is desired. 202 To enable R5 to make the correct choice of exit ASBR the following 203 information is needed: 205 o List of all inter-AS TE links for the local AS. 207 o TE properties of each inter-AS TE link. 209 o AS number of the neighboring AS connected to by each inter-AS TE 210 link. 212 o Identity (TE Router ID) of the neighboring ASBR connected to by 213 each inter-AS TE link. 215 In GMPLS networks further information may also be required to select 216 the correct TE links as defined in [GMPLS-TE]. 218 The example above shows how this information is needed at the entry 219 point ASBRs for each AS (or the PCEs that provide computation 220 services for the ASBRs), but this information is also needed 221 throughout the local AS if path computation function is fully 222 distributed among LSRs in the local AS, for example to support LSPs 223 that have start points (ingress nodes) within the AS. 225 2.3. Backward Recursive Path Computation 227 Another scenario using PCE techniques has the same problem. [BRPC] 228 defines a PCE-based TE LSP computation method (called Backward 229 Recursive Path Computation) to compute optimal inter-domain 230 constrained MPLS-TE or GMPLS LSPs. In this path computation method, a 231 specific set of traversed domains (ASes) are assumed to be selected 232 before computation starts. Each downstream PCE in domain(i) returns 233 to its upstream neighbor PCE in domain(i-1) a multipoint-to-point 234 tree of potential paths. Each tree consists of the set of paths from 235 all Boundary Nodes located in domain(i) to the destination where each 236 path satisfies the set of required constraints for the TE LSP 237 (bandwidth, affinities, etc.). 239 So a PCE needs to select Boundary Nodes (that is, ASBRs) that provide 240 connectivity from the upstream AS. In order that the tree of paths 241 provided by one PCE to its neighbor can be correlated, the identities 242 of the ASBRs for each path need to be referenced, so the PCE must 243 know the identities of the ASBRs in the remote AS reached by any 244 inter-AS TE link, and, in order that it provides only suitable paths 245 in the tree, the PCE must know the TE properties of the inter-AS TE 246 links. See the following figure as an example: 248 PCE1<------>PCE2<-------->PCE3 249 / : : 250 / : : 251 R1------R3----R5-----R7------R9-----R11 252 | | \ | / | 253 | | \ | ---- | 254 | | \ | / | 255 R2------R4----R6 --R8------R10----R12 256 : : 257 <-- AS1 -->:<---- AS2 --->:<--- AS3 ---> 259 Figure 2: BRPC for Inter-AS Reference Model 261 The figure shows three ASes (AS1, AS2, and AS3), three PCEs(PCE1, 262 PCE2, and PCE3) and twelve LSRs (R1 through R12). R3 and R4 are ASBRs 263 in AS1. R5, R6, R7, and R8 are ASBRs in AS2. R9 and R10 are ASBRs in 264 AS3. PCE1, PCE2, and PCE3 cooperate to perform inter-AS path 265 computation and are responsible for path segment computation within 266 their own domains. 268 If an inter-AS TE LSP is planned to be established from R1 to R12, 269 the traversed domains are assumed to be selected: AS1->AS2->AS3, and 270 the PCE chain is: PCE1->PCE2->PCE3. First, the path computation 271 request originated from the PCC (R1) is relayed by PCE1 and PCE2 272 along the PCE chain to PCE3, then PCE3 begins to compute the path 273 segments from the entry boundary nodes that provide connection from 274 AS2 to the destination (R12). But, to provide suitable path segments, 275 PCE3 must determine which entry boundary nodes provide connectivity 276 to its upstream neighbor AS (identified by its AS number) , and must 277 know the TE properties of the inter-AS TE links. In the same way, 278 PCE2 also needs to determine the entry boundary nodes according to 279 its upstream neighbor AS and the inter-AS TE link capabilities. 281 Thus, to support Backward Recursive Path Computation the same 282 information as listed in Section 2.2 is required. 284 3. Extensions to ISIS-TE 286 Note that this document does not define mechanisms for distribution 287 of TE information from one AS to another, does not distribute any 288 form of TE reachability information for destinations outside the AS, 289 does not change the PCE architecture or usage, does not suggest or 290 recommend any form of TE aggregation, and does not feed private 291 information between ASes. See section 2.1. 293 In this document, two new sub-TLVs are added to the extended IS 294 reachability TLV to carry the information about the neighboring AS 295 number and the remote ASBR ID of an inter-AS link. A new TLV, which 296 is referred to as inter-AS reachability TLV, is defined to flood the 297 information about the neighboring AS and the remote ASBR ID within a 298 whole AS. 300 3.1. Remote AS Number Sub-TLV 302 As described in [ISIS-TE], the Extended IS reachability TLV describes 303 a single link and consists of a set of sub-TLVs. A new sub-TLV, the 304 Remote AS Number sub-TLV is added to the extended IS reachability TLV 305 when advertising inter-AS links. The Remote AS Number sub-TLV 306 specifies the AS number of the neighboring AS to which the advertised 307 link connects. 309 The Remote AS number sub-TLV is TLV type 23 (which needs to be 310 confirmed by IANA), and is four octets in length. The format is as 311 follows: 313 0 1 2 3 314 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 315 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 316 | Type | Length | 317 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 318 | Remote AS Number | 319 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 321 The Remote AS number field has 4 octets. When only two octets are 322 used for the AS number, as in current deployments, the left (high- 323 order) two octets MUST be set to zero. The Remote AS Number Sub-TLV 324 MUST be included when a router advertises an inter-AS TE link. 326 3.2. Remote ASBR ID Sub-TLV 328 A new sub-TLV, which is referred to as the Remote ASBR ID sub-TLV, is 329 added to the extended IS reachability TLV when advertising inter-AS 330 links. The remote ASBR ID sub-TLV specifies the identifier of the 331 remote ASBR to which the advertised inter-AS link connects, which 332 could be any stable and routable address of the remote ASBR (e.g., 333 the Router ID, TE Router ID or interface address). The TE Router ID 334 is RECOMMENDED. 336 The Remote ASBR ID sub-TLV is TLV type 24 (which needs to be 337 confirmed by IANA), and is four or sixteen octets in length. The 338 format of the remote ASBR ID sub-TLV is as follows: 340 0 1 2 3 341 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 342 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 343 | Type | Length | 344 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 345 | Remote ASBR ID | 346 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 348 or 350 0 1 2 3 351 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 352 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 353 | Type | Length | 354 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 355 | Remote ASBR ID | 356 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 357 | Remote ASBR ID (continued) | 358 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 359 | Remote ASBR ID (continued) | 360 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 361 | Remote ASBR ID (continued) | 362 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 364 If a router implements traffic engineering for IPv4, the length of 365 the remote ASBR ID is 4. If a router implements traffic engineering 366 for IPv6, the length of the remote ASBR ID is 16. The Remote ASBR ID 367 Sub-TLV MUST be included when a router advertises an inter-AS TE 368 link . 370 3.3. Inter-AS Reachability TLV 372 The inter-AS reachability TLV has type 141 (which needs to be 373 confirmed by IANA). This is an optional TLV, when needed, it is used 374 to flood the reachability information of the inter-AS links within a 375 whole AS. And such reachability information SHOULD include the 376 neighboring AS number and the remote ASBR ID to which an inter-AS 377 link connects. The inter-AS reachability TLV contains a data 378 structure consisting of: 380 6 octets of System ID 381 1 octet of Pseudonode Number 382 1 octet flags 383 1 bit of up/down information 384 1 bit indicating the presence of sub-TLVs 385 6 bits reserved 386 1 octet of length of sub-TLVs 387 0-246 octets of sub-TLVs 388 where each sub-TLV consists of a sequence of: 389 1 octet of sub-type 390 1 octet of length of the value field of the sub-TLV 391 0-244 octets of value 393 In this document, two sub-TLVs are defined for the inter-AS 394 Reachability TLV, they are: 396 Sub-TLV type Length Name 397 ------------ ------ --------------------- 398 23 4 Remote AS number 399 24 4or16 Remote ASBR Identifier 401 These two sub-TLVs have the same format and semantics as defined in 402 Section 3.1 and section 3.2 of this memo. 404 4. Procedure for Inter-AS TE Links 406 When TE is enabled on an inter-AS link and the link is up, the ASBR 407 SHOULD advertise this link using the normal procedures for ISIS-TE 408 [ISIS-TE]. When either the link is down or TE is disabled on the 409 link , the ASBR SHOULD withdraw the advertisement. When there are 410 changes to the TE parameters for the link (for example, when the 411 available bandwidth changes) the ASBR SHOULD re-advertise the link, 412 but the ASBR MUST take precautions against excessive re- 413 advertisements. 415 Hellos MUST NOT be exchanged (and consequently, an ISIS adjacency 416 MUST NOT be formed) over the inter-AS link. 418 The information advertised comes from the ASBR's knowledge of the TE 419 capabilities of the link, the ASBR's knowledge of the current status 420 and usage of the link, and configuration at the ASBR of the remote AS 421 number and remote ASBR TE Router ID. 423 When the inter-AS reachability information needs to reach all routers 424 (including area border routers, ASBRs, and PCEs) in the AS, the ASBR 425 SHOULD carry the Remote AS sub-TLV and Remote ASBR ID sub-TLV in the 426 inter-AS reachability TLV. As defined in Section 4.1 of [ISIS-TE], 427 the inter-AS reachability TLV also defines an up/down bit to 428 facilitate the redistribution of inter-AS reachability information 429 freely between level 1 and level 2. The semantics of the up/down bit 430 in the new inter-AS reachability TLV are identical to the semantics 431 of the up/down bit defined in [ISIS-TE]. That is, the up/down bit 432 SHALL be set to 0 when the inter-AS reachability information first 433 injected into ISIS [ISIS], and the up/dawn bit SHALL be set to 1 if 434 the inter-AS reachability information needs to be advertised from 435 high level to low level. 437 Legacy routers receiving an advertisement for an inter-AS TE link are 438 able to ignore it because they do not know the new TLV and sub-TLVs 439 that are defined in Section 3 in this document. They will continue to 440 flood the LSP, but will not attempt to use the information received 441 as if the link were an intra-AS TE link. 443 Since there is no ISIS adjacency running on the inter-AS link, the 444 local ASBR SHOULD do a "proxy" advertisement for the backward 445 direction of an inter-AS TE link, which facilitates a path 446 computation entity to do a 2-way check before including the link in a 447 path computation. As the objective of such a "proxy" advertisement is 448 to avoid using an inter-AS TE link when the backward direction of the 449 inter-AS TE link is unavailable or unsuitable, only some mandatory or 450 essential TE information needs to be advertised, i.e. the Link ID, 451 the Link Type, and the Remote AS number of an inter-AS TE link. 453 Routers or PCEs that are capable of processing advertisements of 454 inter-AS TE links SHOULD NOT use such links to compute paths that 455 exit an AS to a remote ASBR and then immediately re-enter the AS 456 through another TE link. Such paths would constitute extremely rare 457 occurrences and SHOULD NOT be allowed except as the result of 458 specific policy configurations at the router or PCE computing the 459 path. 461 5. Security Considerations 463 The protocol extensions defined in this document are relatively minor 464 and can be secured within the AS in which they are used by the 465 existing ISIS security mechanisms. 467 There is no exchange of information between ASes, and no change to 468 the ISIS security relationship between the ASes. In particular, since 469 no ISIS adjacency is formed on the inter-AS links, there is no 470 requirement for ISIS security between the ASes. 472 It should be noted, however, that some of the information included in 473 these new advertisements(the remote AS number and the remote ASBR ID) 474 are obtained from a neighboring administration and cannot be verified 475 in anyway. Since the means of delivery of this information is likely 476 to be part of a commercial relationship, the source of the 477 information should be carefully checked before it is entered as 478 configuration information at the ASBR responsible for advertising the 479 inter-AS TE links. 481 6. IANA Considerations 483 IANA is requested to make the following allocations from registries 484 under its control. 486 6.1. Inter-AS Reachability TLV 488 This document defines the following new ISIS TLV type that needs to 489 be reflected in the ISIS TLV code-point registry as described in 490 Section 3.3: 492 Type Description IIH LSP SNP 493 ---- ---------------------- --- --- --- 494 141 Inter-AS reachability n y n 495 information 497 6.2. Sub-TLVs for the Inter-AS Reachability TLV 499 This document defines the following new sub-TLV types of top- 500 level TLV 141 that need to be reflected in the ISIS sub-TLV registry 501 for TLV 141 as described in Sections 3.3 and 6.1: 503 Type Description Length 504 ---- ------------------------------ -------- 505 23 Remote AS number 4 506 24 Remote ASBR Identifier 4 or 16 508 6.3. Sub-TLVs for the Extended IS Reachability TLV 510 This document also defines the following new sub-TLV types of top- 511 level TLV 22 that need to be reflected in the ISIS sub-TLV registry 512 for TLV 22 as described in Section 3.1: 514 Type Description Length 515 ---- ------------------------------ -------- 516 23 Remote AS number 4 517 24 Remote ASBR Identifier 4 or 16 519 7. Acknowledgments 521 The authors would like to thank Adrian Farrel, Jean-Louis Le Roux, 522 Christian Hopps, and Les Ginsberg for their review and comments to 523 this document. 525 8. References 527 8.1. Normative References 529 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 530 Requirement Levels", BCP 14, RFC 2119, March 1997. 532 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., 533 and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP 534 Tunnels", RFC 3209, December 2001. 536 [ISIS] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and 537 dual environments", RFC 1195, December 1990. 539 8.2. Informative References 541 [INTER-AS-TE-REQ] Zhang and Vasseur, "MPLS Inter-AS Traffic 542 Engineering Requirements", RFC4216, November 2005. 544 [PD-PATH] Ayyangar, A., Vasseur, JP., and Zhang, R., "A Per-domain 545 path computation method for establishing Inter-domain", 546 draft-ietf-ccamp-inter-domain-pd-path-comp, (work in 547 progress). 549 [BRPC] JP. Vasseur, Ed., R. Zhang, N. Bitar, JL. Le Roux, "A Backward 550 Recursive PCE-based Computation (BRPC) procedure to compute 551 shortest inter-domain Traffic Engineering Label Switched 552 Paths ", draft-ietf-pce-brpc, (work in progress) 554 [PCE] Farrel, A., Vasseur, JP., and Ash, J., "A Path Computation 555 Element (PCE)-Based Architecture", RFC4655, August 2006. 557 [ISIS-TE-V3] Harrison, J., Berger, J., and Bartlett, M., "IPv6 558 Traffic Engineering in IS-IS", draft-ietf-isis-ipv6-te, 559 {work in progress}. 561 [ISIS-TE] Smit, H. and T. Li, "Intermediate System to Intermediate 562 System (IS-IS) Extensions for Traffic Engineering (TE)", 563 RFC 3784, June 2004. 565 [GMPLS-TE] K.Kompella and Y.Rekhter, "IS-IS Extensions in Support of 566 Generalized Multi-Protocol Label Switching", RFC 4205, 567 October 2005. 569 Authors' Addresses 571 Mach Chen 572 Huawei Technologies Co.,Ltd 573 KuiKe Building, No.9 Xinxi Rd., 574 Hai-Dian District 575 Beijing, 100085 576 P.R. China 578 Email: mach@huawei.com 580 Renhai Zhang 581 Huawei Technologies Co.,Ltd 582 KuiKe Building, No.9 Xinxi Rd., 583 Hai-Dian District 584 Beijing, 100085 585 P.R. China 587 Email: zhangrenhai@huawei.com 589 Duanxiao Dong 590 China Mobile 591 53A,Xibianmennei Ave,Xunwu District 592 Beijing, China 594 Email: duanxiaodong@chinamobile.com 596 Intellectual Property Statement 598 The IETF takes no position regarding the validity or scope of any 599 Intellectual Property Rights or other rights that might be claimed to 600 pertain to the implementation or use of the technology described in 601 this document or the extent to which any license under such rights 602 might or might not be available; nor does it represent that it has 603 made any independent effort to identify any such rights. 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Please address the information to the IETF at 618 ietf-ipr@ietf.org. 620 Disclaimer of Validity 622 This document and the information contained herein are provided on an 623 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 624 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND 625 THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS 626 OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF 627 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 628 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 630 Copyright Statement 632 Copyright (C) The IETF Trust (2007). 634 This document is subject to the rights, licenses and restrictions 635 contained in BCP 78, and except as set forth therein, the authors 636 retain all their rights.