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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) -- Possible downref: Non-RFC (?) normative reference: ref. '4' -- Possible downref: Non-RFC (?) normative reference: ref. '6' ** Obsolete normative reference: RFC 2370 (ref. '8') (Obsoleted by RFC 5250) -- Possible downref: Non-RFC (?) normative reference: ref. '9' -- Obsolete informational reference (is this intentional?): RFC 2434 (ref. '10') (Obsoleted by RFC 5226) Summary: 3 errors (**), 0 flaws (~~), 2 warnings (==), 6 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group D. Katz 3 Internet Draft Juniper Networks 4 Category: Standards Track D. Yeung 5 Expires: February 2003 Procket Networks 6 K. Kompella 7 Juniper Networks 8 August 2002 10 Traffic Engineering Extensions to OSPF Version 2 11 draft-katz-yeung-ospf-traffic-07.txt 13 Status 15 This document is an Internet-Draft and is in full conformance with 16 all provisions of Section 10 of RFC2026. 18 Internet-Drafts are working documents of the Internet Engineering 19 Task Force (IETF), its areas, and its working groups. Note that 20 other groups may also distribute working documents as Internet- 21 Drafts. 23 Internet-Drafts are draft documents valid for a maximum of six months 24 and may be updated, replaced, or obsoleted by other documents at any 25 time. It is inappropriate to use Internet- Drafts as reference 26 material or to cite them other than as "work in progress." 28 The list of current Internet-Drafts can be accessed at 29 http://www.ietf.org/ietf/1id-abstracts.txt 31 The list of Internet-Draft Shadow Directories can be accessed at 32 http://www.ietf.org/shadow.html. 34 Copyright Notice 36 Copyright (C) The Internet Society (2002). All Rights Reserved. 38 Abstract 40 This document describes extensions to the OSPF protocol version 2 to 41 support intra-area Traffic Engineering, using Opaque Link State 42 Advertisements. 44 Changes 46 Changes from the -06 version (this section to be removed before 47 publication). 49 Comments from the ADs incorporated, as well as minor editing changes 50 to conform to draft-rfc-editor-rfc2223bis-02.txt. 52 Clean up front page headers. 53 (First page) 54 Clarify that this memo is for *intra-area* TE. 55 (Title, Abstract, section 1.2) 56 Add a "Conventions" section (rfc 2119). 57 (Section 1.3) 58 Clarify what should be done with Reserved field in section 2.2. 59 (Section 2.2) 60 Add an IANA Considerations section. 61 (Section 2.3.2, 2.4.2 and 8) 62 Clarify "IEEE Floating Point Format", and add reference. 63 (Section 2.4.2) 64 Clarify text for Resource Class/Color (match IS-IS TE text). 65 (Section 2.5.9) 66 Add text on originating TE LSAs. 67 (Section 3) 68 Broke up references into Normative and Informative (for now, 69 IS-IS TE is Informative, pending reply from Routing ADs). 70 Add IPR Notices and Full Copyright Notice, as per rfc 2026. 72 1. Introduction 74 This document specifies a method of adding traffic engineering 75 capabilities to OSPF Version 2 [1]. The architecture of traffic 76 engineering is described in [2]. The semantic content of the 77 extensions is essentially identical to the corresponding extensions 78 to IS-IS [3]. It is expected that the traffic engineering extensions 79 to OSPF will continue to mirror those in IS-IS. 81 The extensions provide a way of describing the traffic engineering 82 topology (including bandwidth and administrative constraints) and 83 distributing this information within a given OSPF area. This 84 topology does not necessarily match the regular routed topology, 85 though this proposal depends on Network LSAs to describe multiaccess 86 links. 88 1.1. Applicability 90 Many of the extensions specified in this document are in response to 91 the requirements stated in [2], and thus are referred to as "traffic 92 engineering extensions", and are also commonly associated with MPLS 93 Traffic Engineering. A more accurate (albeit bland) designation is 94 "extended link attributes", as what is proposed is simply to add more 95 attributes to links in OSPF advertisements. 97 The information made available by these extensions can be used to 98 build an extended link state database just as router LSAs are used to 99 build a "regular" link state database; the difference is that the 100 extended link state database (referred to below as the traffic 101 engineering database) has additional link attributes. Uses of the 102 traffic engineering database include: 104 o monitoring the extended link attributes; 105 o local constraint-based source routing; and 106 o global traffic engineering. 108 For example, an OSPF-speaking device can participate in an OSPF area, 109 build a traffic engineering database, and thereby report on the 110 reservation state of links in that area. 112 In "local constraint-based source routing", a router R can compute a 113 path from a source node A to a destination node B; typically, A is R 114 itself, and B is specified by a "router address" (see below). This 115 path may be subject to various constraints on the attributes of the 116 links and nodes that the path traverses, e.g., use green links that 117 have unreserved bandwidth of at least 10Mbps. This path could then 118 be used to carry some subset of the traffic from A to B, forming a 119 simple but effective means of traffic engineering. How the subset of 120 traffic is determined, and how the path is instantiated is beyond the 121 scope of this document; suffice it to say that one means of defining 122 the subset of traffic is "those packets whose IP destinations were 123 learned from B", and one means of instantiating paths is using MPLS 124 tunnels. As an aside, note that constraint-based routing can be NP- 125 hard, or even unsolvable, depending on the nature of the attributes 126 and constraints and thus many implementations will use heuristics. 127 Consequently, we don't attempt to sketch an algorithm here. 129 Finally, for "global traffic engineering", a device can build a 130 traffic engineering database, input a traffic matrix and an 131 optimization function, crunch on the information, and thus compute 132 optimal or near-optimal routing for the entire network. The device 133 can subsequently monitor the traffic engineering topology and react 134 to changes by recomputing the optimal routes. 136 1.2. Limitations 138 As mentioned above, this document specifies extensions and procedures 139 for intra-area distribution of Traffic Engineering information. 140 Methods for inter-area and inter-AS (Autonomous System) are not 141 discussed here. 143 The extensions specified in this document capture the reservation 144 state of point-to-point links. The reservation state of multiaccess 145 links is not accurately reflected, except in the special case that 146 there are only two devices in the multiaccess subnetwork. 148 This document also does not support unnumbered links. This 149 deficiency is addressed in [4]; see also [5] and [6]. 151 1.3. Conventions 153 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 154 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 155 document are to be interpreted as described in RFC 2119 [7]. 157 2. LSA Format 159 2.1. LSA type 161 This extension makes use of the Opaque LSA [8]. 163 Three types of Opaque LSAs exist, each of which has different 164 flooding scope. This proposal uses only Type 10 LSAs, which have 165 area flooding scope. 167 One new LSA is defined, the Traffic Engineering LSA. This LSA 168 describes routers, point-to-point links, and connections to 169 multiaccess networks (similar to a Router LSA). For traffic 170 engineering purposes, the existing Network LSA suffices for 171 describing multiaccess links, so no additional LSA is defined for 172 this purpose. 174 2.2. LSA ID 176 The LSA ID of an Opaque LSA is defined as having eight bits of type 177 and 24 bits of type-specific data. The Traffic Engineering LSA uses 178 type 1. The remaining 24 bits are broken up into eight bits of 179 reserved space (which SHOULD be zero on transmission and ignored on 180 receipt) and sixteen bits of instance: 182 0 1 2 3 183 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 1 184 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 185 | 1 | Reserved | Instance | 186 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 188 The Instance field is an arbitrary value used to maintain multiple 189 Traffic Engineering LSAs. A maximum of 65536 Traffic Engineering 190 LSAs may be sourced by a single system. The LSA ID has no 191 topological significance. 193 2.3. LSA Format Overview 195 2.3.1. LSA Header 197 The Traffic Engineering LSA starts with the standard LSA header: 199 0 1 2 3 200 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 1 201 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 202 | LS age | Options | 10 | 203 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 204 | 1 | Reserved | Instance | 205 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 206 | Advertising Router | 207 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 208 | LS sequence number | 209 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 210 | LS checksum | Length | 211 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 213 2.3.2. TLV Header 215 The LSA payload consists of one or more nested Type/Length/Value 216 (TLV) triplets for extensibility. The format of each TLV is: 218 0 1 2 3 219 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 1 220 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 221 | Type | Length | 222 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 223 | Value... | 224 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 226 The Length field defines the length of the value portion in octets 227 (thus a TLV with no value portion would have a length of zero). The 228 TLV is padded to four-octet alignment; padding is not included in 229 the length field (so a three octet value would have a length of 230 three, but the total size of the TLV would be eight octets). Nested 231 TLVs are also 32-bit aligned. Unrecognized types are ignored. 233 This memo defines Types 1 and 2. See the IANA Considerations section 234 for allocation of new Types. 236 2.4. LSA payload details 238 An LSA contains one top-level TLV. 240 There are two top-level TLVs defined: 242 1 - Router Address 243 2 - Link 245 2.4.1. Router Address TLV 247 The Router Address TLV specifies a stable IP address of the 248 advertising router that is always reachable if there is any 249 connectivity to it. This is typically implemented as a "loopback 250 address"; the key attribute is that the address does not become 251 unusable if an interface is down. In other protocols this is known 252 as the "router ID," but for obvious reasons this nomenclature is 253 avoided here. 255 If IS-IS is also active in the domain, this address can also be used 256 to compute the mapping between the OSPF and IS-IS topologies. For 257 example, suppose a router R is advertising both IS-IS and OSPF 258 Traffic Engineering LSAs, and suppose further that some router S is 259 building a single Traffic Engineering Database (TED) based on both 260 IS-IS and OSPF TE information. R may then appear as two separate 261 nodes in S's TED; however, if both the IS-IS and OSPF LSAs generated 262 by R contain the same Router Address, then S can determine that the 263 IS-IS TE LSA and the OSPF TE LSA from R are indeed from a single 264 router. 266 The router address TLV is type 1, and has a length of 4, and the 267 value is the four octet IP address. It must appear in exactly one 268 Traffic Engineering LSA originated by a router. 270 2.4.2. Link TLV 272 The Link TLV describes a single link. It is constructed of a set of 273 sub-TLVs. There are no ordering requirements for the sub-TLVs. 275 Only one Link TLV shall be carried in each LSA, allowing for fine 276 granularity changes in topology. 278 The Link TLV is type 2, and the length is variable. 280 The following sub-TLVs are defined: 282 1 - Link type (1 octet) 283 2 - Link ID (4 octets) 284 3 - Local interface IP address (4 octets) 285 4 - Remote interface IP address (4 octets) 286 5 - Traffic engineering metric (4 octets) 287 6 - Maximum bandwidth (4 octets) 288 7 - Maximum reservable bandwidth (4 octets) 289 8 - Unreserved bandwidth (32 octets) 290 9 - Administrative group (4 octets) 292 This memo defines sub-Types 1 through 9. See the IANA Considerations 293 section for allocation of new sub-Types. 295 The Link Type and Link ID sub-TLVs are mandatory, i.e., must appear 296 exactly once. All other sub-TLVs defined here may occur at most 297 once. These restrictions need not apply to future sub-TLVs. 298 Unrecognized sub-TLVs are ignored. 300 Various values below use the (32 bit) IEEE Floating Point format. 301 For quick reference, this format is as follows: 303 0 1 2 3 304 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 1 305 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 306 |S| Exponent | Fraction | 307 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 309 where S is the sign; Exponent is the exponent base 2 in "excess 127" 310 notation; and Fraction is the mantissa - 1, with an implied binary 311 point in front of it. Thus the above represents the value 312 (-1)**(S) * 2**(Exponent-127) * (1 + Fraction) 314 For more details, refer to [9]. 316 2.5. Sub-TLV Details 318 2.5.1. Link Type 320 The Link Type sub-TLV defines the type of the link: 322 1 - Point-to-point 323 2 - Multiaccess 325 The Link Type sub-TLV is TLV type 1, and is one octet in length. 327 2.5.2. Link ID 329 The Link ID sub-TLV identifies the other end of the link. For point- 330 to-point links, this is the Router ID of the neighbor. For 331 multiaccess links, this is the interface address of the designated 332 router. The Link ID is identical to the contents of the Link ID 333 field in the Router LSA for these link types. 335 The Link ID sub-TLV is TLV type 2, and is four octets in length. 337 2.5.3. Local Interface IP Address 339 The Local Interface IP Address sub-TLV specifies the IP address(es) 340 of the interface corresponding to this link. If there are multiple 341 local addresses on the link, they are all listed in this sub-TLV. 343 The Local Interface IP Address sub-TLV is TLV type 3, and is 4N 344 octets in length, where N is the number of local addresses. 346 2.5.4. Remote Interface IP Address 348 The Remote Interface IP Address sub-TLV specifies the IP address(es) 349 of the neighbor's interface corresponding to this link. This and the 350 local address are used to discern multiple parallel links between 351 systems. If the Link Type of the link is Multiaccess, the Remote 352 Interface IP Addess is set to 0.0.0.0 . 354 The Remote Interface IP Address sub-TLV is TLV type 4, and is 4N 355 octets in length, where N is the number of neighbor addresses. 357 2.5.5. Traffic Engineering Metric 359 The Traffic Engineering Metric sub-TLV specifies the link metric for 360 traffic engineering purposes. This metric may be different than the 361 standard OSPF link metric. Typically, this metric is assigned by a 362 network admistrator. 364 The Traffic Engineering Metric sub-TLV is TLV type 5, and is four 365 octets in length. 367 2.5.6. Maximum Bandwidth 369 The Maximum Bandwidth sub-TLV specifies the maximum bandwidth that 370 can be used on this link in this direction (from the system 371 originating the LSA to its neighbor), in IEEE floating point format. 372 This is the true link capacity. The units are bytes per second. 374 The Maximum Bandwidth sub-TLV is TLV type 6, and is four octets in 375 length. 377 2.5.7. Maximum Reservable Bandwidth 379 The Maximum Reservable Bandwidth sub-TLV specifies the maximum 380 bandwidth that may be reserved on this link in this direction, in 381 IEEE floating point format. Note that this may be greater than the 382 maximum bandwidth (in which case the link may be oversubscribed). 383 This SHOULD be user-configurable; the default value should be the 384 Maximum Bandwidth. The units are bytes per second. 386 The Maximum Reservable Bandwidth sub-TLV is TLV type 7, and is four 387 octets in length. 389 2.5.8. Unreserved Bandwidth 391 The Unreserved Bandwidth sub-TLV specifies the amount of bandwidth 392 not yet reserved at each of the eight priority levels, in IEEE 393 floating point format. The values correspond to the bandwidth that 394 can be reserved with a setup priority of 0 through 7, arranged in 395 increasing order with priority 0 occurring at the start of the sub- 396 TLV, and priority 7 at the end of the sub-TLV. The initial values 397 (before any bandwidth is reserved) are all set to the Maximum 398 Reservable Bandwidth. Each value will be less than or equal to the 399 Maximum Reservable Bandwidth. The units are bytes per second. 401 The Unreserved Bandwidth sub-TLV is TLV type 8, and is 32 octets in 402 length. 404 2.5.9. Administrative Group 406 The Administrative Group sub-TLV contains a 4-octet bit mask assigned 407 by the network administrator. Each set bit corresponds to one 408 administrative group assigned to the interface. A link may belong to 409 multiple groups. 411 By convention the least significant bit is referred to as 'group 0', 412 and the most significant bit is referred to as 'group 31'. 414 The Administrative Group is also called Resource Class/Color [2]. 416 The Administrative Group sub-TLV is TLV type 9, and is four octets in 417 length. 419 3. Elements of Procedure 421 Routers shall originate Traffic Engineering LSAs whenever the LSA 422 contents change, and whenever otherwise required by OSPF (an LSA 423 refresh, for example). Note that this does not mean that every 424 change must be flooded immediately; an implementation MAY set 425 thresholds (for example, a bandwidth change threshold) that trigger 426 immediate flooding, and initiate flooding of other changes after a 427 short time interval. In any case, the origination of Traffic 428 Engineering LSAs SHOULD be rate-limited to at most one every 429 MinLSInterval [1]. 431 Upon receipt of a changed Traffic Engineering LSA or Network LSA 432 (since these are used in traffic engineering calculations), the 433 router should update its traffic engineering database. No SPF or 434 other route calculations are necessary. 436 4. Compatibility Issues 438 There should be no interoperability issues with routers that do not 439 implement these extensions, as the Opaque LSAs will be silently 440 ignored. 442 The result of having routers that do not implement these extensions 443 is that the traffic engineering topology will be missing pieces; 444 however, if the topology is connected, TE paths can still be 445 calculated and ought to work. 447 5. Normative References 449 [1] Moy, J., "OSPF Version 2", RFC 2328, April 1998. 451 [4] Kompella, K., Rekhter, Y., et al, "OSPF Extensions in Support of 452 Generalized MPLS," work in progress. 454 [6] Kompella, K., and Rekhter, Y., "Signalling Unnumbered Links in 455 RSVP-TE," work in progress. 457 [7] Bradner, S., "Key words for use in RFCs to Indicate Requirement 458 Levels", BCP 14, RFC 2119, March 1997. 460 [8] Coltun, R., "The OSPF Opaque LSA Option," RFC 2370, July 1998. 462 [9] IEEE, "IEEE Standard for Binary Floating-Point Arithmetic", 463 Standard 754-1985, 1985 (ISBN 1-5593-7653-8). 465 6. Informative References 467 [2] Awduche, D., et al, "Requirements for Traffic Engineering Over 468 MPLS," RFC 2702, September 1999. 470 [3] Smit, H. and T. Li, "ISIS Extensions for Traffic Engineering," 471 work in progress. 473 [5] Kompella, K., Rekhter, Y., and Kullberg, A., "Signalling 474 Unnumbered Links in CR-LDP," work in progress. 476 [10] Narten, T., and Alvestrand, H., "Guidelines for Writing an IANA 477 Considerations Section in RFCs", RFC 2434, BCP 26, October 1998. 479 7. Security Considerations 481 This document raises no new security issues for OSPF. 483 8. IANA Considerations 485 The top level Types in a TE LSA as well as Types for sub-TLVs in a TE 486 Link TLV are to be registered with IANA. 488 Following the guidelines set in [10], top level Types in TE LSAs from 489 3 through 32767 are to be assigned by Expert Review (the said Expert 490 to be decided by the IESG). Types from 32768 through 65535 are 491 reserved for Private Use. In all cases, assigned values Types MUST 492 be registered with IANA. 494 Also, sub-Types of a TE Link TLV from 10 to 32767 are to be assigned 495 by Expert Review; values from 32768 through 32772 are reserved for 496 Private Use; and values from 32773 through 65535 are to be assigned 497 First Come First Served. In all cases, assigned values are to be 498 registered with IANA. 500 9. Authors' Addresses 502 Dave Katz 503 Juniper Networks 504 1194 N. Mathilda Ave. 505 Sunnyvale, CA 94089 USA 507 Phone: +1 408 745 2000 508 Email: dkatz@juniper.net 510 Derek M. Yeung 511 Procket Networks, Inc. 512 1100 Cadillac Court 513 Milpitas, CA 95035 USA 515 Phone: +1 408 635-7900 516 Email: myeung@procket.com 518 Kireeti Kompella 519 Juniper Networks 520 1194 N. Mathilda Ave. 521 Sunnyvale, CA 94089 USA 523 Phone: +1 408 745 2000 524 Email: kireeti@juniper.net 526 10. IPR Notices 528 The IETF takes no position regarding the validity or scope of any 529 intellectual property or other rights that might be claimed to 530 pertain to the implementation or use of the technology described in 531 this document or the extent to which any license under such rights 532 might or might not be available; neither does it represent that it 533 has made any effort to identify any such rights. Information on the 534 IETF's procedures with respect to rights in standards-track and 535 standards-related documentation can be found in BCP-11. 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