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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. 'IEEE754' Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 Network Working Group S. Giacalone 2 Internet Draft Unaffiliated 3 Intended status: Proposed Standard 4 Expires: July 2015 D. Ward 5 Cisco Systems 7 J. Drake 8 Juniper Networks 10 A. Atlas 11 Juniper Networks 13 S. Previdi 14 Cisco Systems 16 January 09, 2015 18 OSPF Traffic Engineering (TE) Metric Extensions 19 draft-ietf-ospf-te-metric-extensions-11.txt 21 Abstract 23 In certain networks, such as, but not limited to, financial 24 information networks (e.g., stock market data providers), network 25 performance information (e.g., link propagation delay) is becoming 26 critical to data path selection. 28 This document describes common extensions to RFC 3630 "Traffic 29 Engineering (TE) Extensions to OSPF Version 2" and RFC 5329 "Traffic 30 Engineering Extensions to OSPF Version 3" to enable network 31 performance information to be distributed in a scalable fashion. The 32 information distributed using OSPF TE Metric Extensions can then be 33 used to make path selection decisions based on network performance. 35 Note that this document only covers the mechanisms by which network 36 performance information is distributed. The mechanisms for measuring 37 network performance information or using that information, once 38 distributed, are outside the scope of this document. 40 Status of this Memo 42 This Internet-Draft is submitted in full conformance with the 43 provisions of BCP 78 and BCP 79. 45 Internet-Drafts are working documents of the Internet Engineering 46 Task Force (IETF), its areas, and its working groups. Note that 47 other groups may also distribute working documents as Internet- 48 Drafts. 50 Internet-Drafts are draft documents valid for a maximum of six months 51 and may be updated, replaced, or obsoleted by other documents at any 52 time. It is inappropriate to use Internet-Drafts as reference 53 material or to cite them other than as "work in progress." 55 The list of current Internet-Drafts can be accessed at 56 http://www.ietf.org/ietf/1id-abstracts.txt 58 The list of Internet-Draft Shadow Directories can be accessed at 59 http://www.ietf.org/shadow.html 61 This Internet-Draft will expire on July 9, 2015. 63 Copyright Notice 65 Copyright (c) 2015 IETF Trust and the persons identified as the 66 document authors. All rights reserved. 68 This document is subject to BCP 78 and the IETF Trust's Legal 69 Provisions Relating to IETF Documents 70 (http://trustee.ietf.org/license-info) in effect on the date of 71 publication of this document. Please review these documents 72 carefully, as they describe your rights and restrictions with respect 73 to this document. Code Components extracted from this document must 74 include Simplified BSD License text as described in Section 4.e of 75 the Trust Legal Provisions and are provided without warranty as 76 described in the Simplified BSD License. 78 Table of Contents 80 1. Introduction...................................................4 81 2. Conventions used in this document..............................5 82 3. TE Metric Extensions to OSPF TE................................5 83 4. Sub-TLV Details................................................7 84 4.1. Unidirectional Link Delay Sub-TLV.........................7 85 4.1.1. Type.................................................7 86 4.1.2. Length...............................................7 87 4.1.3. A bit................................................7 88 4.1.4. Reserved.............................................7 89 4.1.5. Delay Value..........................................7 90 4.2. Min/Max Unidirectional Link Delay Sub-TLV.................8 91 4.2.1. Type.................................................8 92 4.2.2. Length...............................................8 93 4.2.3. A bit................................................8 94 4.2.4. Reserved.............................................8 95 4.2.5. Min Delay............................................9 96 4.2.6. Reserved.............................................9 97 4.2.7 Max Delay.............................................9 98 4.3. Unidirectional Delay Variation Sub-TLV....................9 99 4.3.1. Type................................................10 100 4.3.2. Length..............................................10 101 4.3.3. Reserved............................................10 102 4.3.4. Delay Variation.....................................10 103 4.4. Unidirectional Link Loss Sub-TLV.........................10 104 4.4.1. Type................................................11 105 4.4.2. Length..............................................11 106 4.4.3. A bit...............................................11 107 4.4.4. Reserved............................................11 108 4.4.5. Link Loss...........................................11 109 4.5. Unidirectional Residual Bandwidth Sub-TLV................11 110 4.5.1. Type................................................12 111 4.5.2. Length..............................................12 112 4.5.3. Residual Bandwidth..................................12 113 4.6. Unidirectional Available Bandwidth Sub-TLV...............12 114 4.6.1. Type................................................13 115 4.6.2. Length..............................................13 116 4.6.3. Available Bandwidth.................................13 117 4.7. Unidirectional Utilized Bandwidth Sub-TLV................13 118 4.7.1. Type................................................14 119 4.7.2. Length..............................................14 120 4.7.3. Utilized Bandwidth..................................14 121 5. Announcement Thresholds and Filters...........................14 122 6. Announcement Suppression......................................15 123 7. Network Stability and Announcement Periodicity................15 124 8. Enabling and Disabling Sub-TLVs...............................16 125 9. Static Metric Override........................................16 126 10. Compatibility................................................16 127 11. Security Considerations......................................16 128 12. IANA Considerations..........................................17 129 13. References...................................................17 130 13.1. Normative References....................................17 131 13.2. Informative References..................................18 132 14. Acknowledgments..............................................19 133 15. Author's Addresses...........................................19 135 1. Introduction 137 In certain networks, such as, but not limited to, financial 138 information networks (e.g., stock market data providers), network 139 performance information (e.g., link propagation delay) is becoming as 140 critical to data path selection as other metrics. 142 Because of this, using metrics such as hop count or cost as routing 143 metrics is becoming only tangentially important. Rather, it would be 144 beneficial to be able to make path selection decisions based on 145 network performance information (such as link propagation delay) in a 146 cost-effective and scalable way. 148 This document describes extensions to OSPFv2 and OSPFv3 TE (hereafter 149 called "OSPF TE Metric Extensions"), that can be used to distribute 150 network performance information (viz link propagation delay, delay 151 variation, link loss, residual bandwidth, available bandwidth, and 152 utilized bandwidth). 154 The data distributed by OSPF TE Metric Extensions is meant to be used 155 as part of the operation of the routing protocol (e.g., by replacing 156 cost with link propagation delay or considering bandwidth as well as 157 cost), by enhancing CSPF, or for use by a PCE [RFC4655] or an Alto 158 server [RFC7285]. With respect to CSPF, the data distributed by OSPF 159 TE Metric Extensions can be used to setup, fail over, and fail back 160 data paths using protocols such as RSVP-TE [RFC3209]. 162 Note that the mechanisms described in this document only distribute 163 network performance information. The methods for measuring that 164 information or acting on it once it is distributed are outside the 165 scope of this document. A method for measuring loss and delay in an 166 MPLS network is described in [RFC6374]. 168 While this document does not specify the method for measuring 169 network performance information, any measurement of link propagation 170 delay SHOULD NOT vary significantly based upon the offered traffic 171 load and hence SHOULD NOT include queuing delays. For a forwarding 172 adjacency (FA) [RFC4206], care must be taken that measurement of the 173 link propagation delay avoids significant queuing delay; this can be 174 accomplished in a variety of ways, e.g., measuring with a traffic 175 class that experiences minimal queuing or summing the measured link 176 propagation delay of the links on the FA's path. 178 2. Conventions used in this document 180 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 181 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 182 document are to be interpreted as described in RFC-2119 [RFC2119]. 184 In this document, these words will appear with that interpretation 185 only when in ALL CAPS. Lower case uses of these words are not to be 186 interpreted as carrying RFC-2119 significance. 188 3. TE Metric Extensions to OSPF TE 190 This document defines new OSPF TE sub-TLVs that are used to 191 distribute network performance information. The extensions in this 192 document build on the ones provided in OSPFv2 TE [RFC3630] and OSPFv3 193 TE [RFC5329]. 195 OSPFv2 TE LSAs [RFC3630] are opaque LSAs [RFC5250] with area 196 flooding scope while OSPFv3 Intra-Area-TE-LSAs have their own LSA 197 type, also with area flooding scope; both consist of a single TLV 198 with one or more nested sub-TLVs. The Link TLV is common to both 199 and describes the characteristics of a link between OSPF neighbors. 201 This document defines several additional sub-TLVs for the Link TLV: 203 Type Length Value 205 TBD1 4 Unidirectional Link Delay 207 TBD2 8 Min/Max Unidirectional Link Delay 209 TBD3 4 Unidirectional Delay Variation 211 TBD4 4 Unidirectional Link Loss 213 TBD5 4 Unidirectional Residual Bandwidth 215 TBD6 4 Unidirectional Available Bandwidth 217 TBD7 4 Unidirectional Utilized Bandwidth 218 As can be seen in the list above, the sub-TLVs described in this 219 document carry different types of network performance information. 220 Many (but not all) of the sub-TLVs include a bit called the Anomalous 221 (or A) bit. When the A bit is clear (or when the sub-TLV does not 222 include an A bit), the sub-TLV describes steady state link 223 performance. This information could conceivably be used to construct 224 a steady state performance topology for initial tunnel path 225 computation, or to verify alternative failover paths. 227 When network performance violates configurable link-local thresholds 228 a sub-TLV with the A bit set is advertised. These sub-TLVs could be 229 used by the receiving node to determine whether to move traffic to a 230 backup path, or whether to calculate an entirely new path. From an 231 MPLS perspective, the intent of the A bit is to permit LSP ingress 232 nodes to: 234 A) Determine whether the link referenced in the sub-TLV affects any 235 of the LSPs for which it is ingress. If there are, then: 237 B) The node determines whether those LSPs still meet end-to-end 238 performance objectives. If not, then: 240 C) The node could then conceivably move affected traffic to a pre- 241 established protection LSP or establish a new LSP and place the 242 traffic in it. 244 If link performance then improves beyond a configurable minimum 245 value (reuse threshold), that sub-TLV can be re-advertised with the 246 Anomalous bit cleared. In this case, a receiving node can 247 conceivably do whatever re-optimization (or failback) it wishes 248 (including nothing). 250 The A bit was intentionally omitted from some sub-TLVs to help 251 mitigate oscillations. See section 7. 1. for more information. 253 Link delay, delay variation, and link loss MUST be encoded as 254 integers. Consistent with existing OSPF TE specifications [RFC3630], 255 residual, available, and utilized bandwidth MUST be encoded in IEEE 256 single precision floating point [IEEE754]. Link delay and delay 257 variation MUST be in units of microseconds, link loss MUST be a 258 percentage, and bandwidth MUST be in units of bytes per second. All 259 values (except residual bandwidth) MUST be calculated as rolling 260 averages where the averaging period MUST be a configurable period of 261 time. See section 5. for more information. 263 4. Sub-TLV Details 265 4.1. Unidirectional Link Delay Sub-TLV 267 This sub-TLV advertises the average link delay between two directly 268 connected OSPF neighbors. The delay advertised by this sub-TLV MUST 269 be the delay from the advertising node to its neighbor (i.e., the 270 forward path delay). The format of this sub-TLV is shown in the 271 following diagram: 273 0 1 2 3 274 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 1 275 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 276 | TBD1 | 4 | 277 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 278 |A| RESERVED | Delay | 279 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 281 4.1.1. Type 283 This sub-TLV has a type of TBD1. 285 4.1.2. Length 287 The length is 4. 289 4.1.3. A bit 291 This field represents the Anomalous (A) bit. The A bit is set when 292 the measured value of this parameter exceeds its configured maximum 293 threshold. The A bit is cleared when the measured value falls below 294 its configured reuse threshold. If the A bit is clear, the sub-TLV 295 represents steady state link performance. 297 4.1.4. Reserved 299 This field is reserved for future use. It MUST be set to 0 when sent 300 and MUST be ignored when received. 302 4.1.5. Delay Value 304 This 24-bit field carries the average link delay over a configurable 305 interval in micro-seconds, encoded as an integer value. When set to 306 the maximum value 16,777,215 (16.777215 sec), then the delay is at 307 least that value and may be larger. If there is no value to send 308 (unmeasured and not statically specified), then the sub-TLV should 309 not be sent or be withdrawn. 311 4.2. Min/Max Unidirectional Link Delay Sub-TLV 313 This sub-TLV advertises the minimum and maximum delay values between 314 two directly connected OSPF neighbors. The delay advertised by this 315 sub-TLV MUST be the delay from the advertising node to its neighbor 316 (i.e., the forward path delay). The format of this sub-TLV is shown 317 in the following diagram: 319 0 1 2 3 320 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 1 321 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 322 | TBD2 | 8 | 323 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 324 |A| RESERVED | Min Delay | 325 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 326 | RESERVED | Max Delay | 327 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 329 4.2.1. Type 331 This sub-TLV has a type of TBD2. 333 4.2.2. Length 335 The length is 8. 337 4.2.3. A bit 339 This field represents the Anomalous (A) bit. The A bit is set when 340 one or more measured values exceed a configured maximum threshold. 341 The A bit is cleared when the measured value falls below its 342 configured reuse threshold. If the A bit is clear, the sub-TLV 343 represents steady state link performance. 345 4.2.4. Reserved 347 This field is reserved for future use. It MUST be set to 0 when sent 348 and MUST be ignored when received. 350 4.2.5. Min Delay 352 This 24-bit field carries minimum measured link delay value (in 353 microseconds) over a configurable interval, encoded as an integer 354 value. 356 Implementations MAY also permit the configuration of an offset value 357 (in microseconds) to be added to the measured delay value to 358 advertise operator specific delay constraints. 360 When set to the maximum value 16,777,215 (16.777215 sec), then the 361 delay is at least that value and may be larger. 363 4.2.6. Reserved 365 This field is reserved for future use. It MUST be set to 0 when sent 366 and MUST be ignored when received. 368 4.2.7 Max Delay 370 This 24-bit field carries the maximum measured link delay value (in 371 microseconds) over a configurable interval, encoded as an integer 372 value. 374 Implementations may also permit the configuration of an offset value 375 (in microseconds) to be added to the measured delay value to 376 advertise operator specific delay constraints. 378 It is possible for min delay and max delay to be the same value. 380 When the delay value is set to maximum value 16,777,215 (16.777215 381 sec), then the delay is at least that value and may be larger. 383 4.3. Unidirectional Delay Variation Sub-TLV 385 This sub-TLV advertises the average link delay variation between two 386 directly connected OSPF neighbors. The delay variation advertised by 387 this sub-TLV MUST be the delay from the advertising node to its 388 neighbor (i.e., the forward path delay variation). The format of this 389 sub-TLV is shown in the following diagram: 391 0 1 2 3 392 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 1 393 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 394 | TBD3 | 4 | 395 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 396 | RESERVED | Delay Variation | 397 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 399 4.3.1. Type 401 This sub-TLV has a type of TBD3. 403 4.3.2. Length 405 The length is 4. 407 4.3.3. Reserved 409 This field is reserved for future use. It MUST be set to 0 when sent 410 and MUST be ignored when received. 412 4.3.4. Delay Variation 414 This 24-bit field carries the average link delay variation over a 415 configurable interval in micro-seconds, encoded as an integer value. 416 When set to 0, it has not been measured. When set to the maximum 417 value 16,777,215 (16.777215 sec), then the delay is at least that 418 value and may be larger. 420 4.4. Unidirectional Link Loss Sub-TLV 422 This sub-TLV advertises the loss (as a packet percentage) between two 423 directly connected OSPF neighbors. The link loss advertised by this 424 sub-TLV MUST be the packet loss from the advertising node to its 425 neighbor (i.e., the forward path loss). The format of this sub-TLV is 426 shown in the following diagram: 428 0 1 2 3 429 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 1 430 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 431 | TBD4 | 4 | 432 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 433 |A| RESERVED | Link Loss | 434 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 436 4.4.1. Type 438 This sub-TLV has a type of TBD4 440 4.4.2. Length 442 The length is 4. 444 4.4.3. A bit 446 This field represents the Anomalous (A) bit. The A bit is set when 447 the measured value of this parameter exceeds its configured maximum 448 threshold. The A bit is cleared when the measured value falls below 449 its configured reuse threshold. If the A bit is clear, the sub-TLV 450 represents steady state link performance. 452 4.4.4. Reserved 454 This field is reserved for future use. It MUST be set to 0 when sent 455 and MUST be ignored when received. 457 4.4.5. Link Loss 459 This 24-bit field carries link packet loss as a percentage of the 460 total traffic sent over a configurable interval. The basic unit is 461 0.000003%, where (2^24 - 2) is 50.331642%. This value is the highest 462 packet loss percentage that can be expressed (the assumption being 463 that precision is more important on high speed links than the ability 464 to advertise loss rates greater than this, and that high speed links 465 with over 50% loss are unusable). Therefore, measured values that are 466 larger than the field maximum SHOULD be encoded as the maximum value. 468 4.5. Unidirectional Residual Bandwidth Sub-TLV 470 This sub-TLV advertises the residual bandwidth between two directly 471 connected OSPF neighbors. The residual bandwidth advertised by this 472 sub-TLV MUST be the residual bandwidth from the advertising node to 473 its neighbor. 475 The format of this sub-TLV is shown in the following diagram: 477 0 1 2 3 478 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 1 479 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 480 | TBD5 | 4 | 481 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 482 | Residual Bandwidth | 483 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 485 4.5.1. Type 487 This sub-TLV has a type of TBD5. 489 4.5.2. Length 491 The length is 4. 493 4.5.3. Residual Bandwidth 495 This field carries the residual bandwidth on a link, forwarding 496 adjacency [RFC4206], or bundled link in IEEE floating point format 497 with units of bytes per second. For a link or forwarding adjacency, 498 residual bandwidth is defined to be Maximum Bandwidth [RFC3630] minus 499 the bandwidth currently allocated to RSVP-TE LSPs. For a bundled 500 link, residual bandwidth is defined to be the sum of the component 501 link residual bandwidths. 503 The calculation of Residual Bandwidth is different than that of 504 Unreserved Bandwidth [RFC3630]. Residual Bandwidth subtracts tunnel 505 reservations from Maximum Bandwidth (i.e., the link capacity) 506 [RFC3630] and provides an aggregated remainder across QoS classes. 507 Unreserved Bandwidth [RFC3630], on the other hand, is subtracted from 508 the Maximum Reservable Bandwidth (the bandwidth that can 509 theoretically be reserved) [RFC3630] and provides per-QoS-class 510 remainders. Residual Bandwidth and Unreserved Bandwidth [RFC3630] can 511 be used concurrently, and each has a separate use case (e.g., the 512 former can be used for applications like Weighted ECMP while the 513 latter can be used for call admission control). 515 4.6. Unidirectional Available Bandwidth Sub-TLV 517 This TLV advertises the available bandwidth between two directly 518 connected OSPF neighbors. The available bandwidth advertised by this 519 sub-TLV MUST be the available bandwidth from the advertising node to 520 its neighbor. The format of this sub-TLV is shown in the following 521 diagram: 523 0 1 2 3 524 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 1 525 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 526 | TBD6 | 4 | 527 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 528 | Available Bandwidth | 529 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 531 4.6.1. Type 533 This sub-TLV has a type of TBD6. 535 4.6.2. Length 537 The length is 4. 539 4.6.3. Available Bandwidth 541 This field carries the available bandwidth on a link, forwarding 542 adjacency, or bundled link in IEEE floating point format with units 543 of bytes per second. For a link or forwarding adjacency, available 544 bandwidth is defined to be residual bandwidth (see section 4.5. ) 545 minus the measured bandwidth used for the actual forwarding of non- 546 RSVP-TE LSP packets. For a bundled link, available bandwidth is 547 defined to be the sum of the component link available bandwidths. 549 4.7. Unidirectional Utilized Bandwidth Sub-TLV 551 This Sub-TLV advertises the bandwidth utilization between two 552 directly connected OSPF neighbors. The bandwidth utilization 553 advertised by this sub-TLV MUST be the bandwidth from the advertising 554 node to its neighbor. The format of this Sub-TLV is shown in the 555 following diagram: 557 0 1 2 3 558 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 1 559 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 560 | TBD7 | 4 | 561 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 562 | Utilized Bandwidth | 563 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 565 4.7.1. Type 567 This sub-TLV has a type of TBD7. 569 4.7.2. Length 571 The length is 4. 573 4.7.3. Utilized Bandwidth 575 This field carries the bandwidth utilization on a link, forwarding 576 adjacency, or bundled link in IEEE floating point format with units 577 of bytes per second. For a link or forwarding adjacency, bandwidth 578 utilization represents the actual utilization of the link (i.e., as 579 measured by the advertising node). For a bundled link, bandwidth 580 utilization is defined to be the sum of the component link bandwidth 581 utilizations. 583 5. Announcement Thresholds and Filters 585 The values advertised in all sub-TLVs (except min/max delay and 586 residual bandwidth) MUST represent an average over a period or be 587 obtained by a filter that is reasonably representative of an 588 average. For example, a rolling average is one such filter. 590 Min and max delay MAY be the lowest and/or highest measured value 591 over a measurement interval or MAY make use of a filter, or other 592 technique to obtain a reasonable representation of a min and max 593 value representative of the interval with compensation for outliers. 595 The measurement interval, any filter coefficients, and any 596 advertisement intervals MUST be configurable for each sub-TLV. 598 In addition to the measurement intervals governing re-advertisement, 599 implementations SHOULD provide for each sub-TLV configurable 600 accelerated advertisement thresholds, such that: 602 1. If the measured parameter falls outside a configured upper bound 603 for all but the min delay metric (or lower bound for min delay 604 metric only) and the advertised sub-TLV is not already outside 605 that bound or, 607 2. If the difference between the last advertised value and current 608 measured value exceed a configured threshold then, 610 3. The advertisement is made immediately. 612 4. For sub-TLVs which include an A-bit (except min/max delay), an 613 additional threshold SHOULD be included corresponding to the 614 threshold for which the performance is considered anomalous (and 615 sub-TLVs with the A bit are sent). The A-bit is cleared when the 616 sub-TLV's performance has been below (or re-crosses) this 617 threshold for an advertisement interval(s) to permit fail back. 619 To prevent oscillations, only the high threshold or the low threshold 620 (but not both) may be used to trigger any given sub-TLV that supports 621 both. 623 Additionally, once outside of the bounds of the threshold, any re- 624 advertisement of a measurement within the bounds would remain 625 governed solely by the measurement interval for that sub-TLV. 627 6. Announcement Suppression 629 When link performance values change by small amounts that fall under 630 thresholds that would cause the announcement of a sub-TLV, 631 implementations SHOULD suppress sub-TLV re-advertisement and/or 632 lengthen the period within which they are refreshed. 634 Only the accelerated advertisement threshold mechanism described in 635 section 5 may shorten the re-advertisement interval. 637 All suppression and re-advertisement interval back-off timer features 638 SHOULD be configurable. 640 7. Network Stability and Announcement Periodicity 642 Sections 5 and 6 provide configurable mechanisms to bound the number 643 of re-advertisements. Instability might occur in very large networks 644 if measurement intervals are set low enough to overwhelm the 645 processing of flooded information at some of the routers in the 646 topology. Therefore care should be taken in setting these values. 648 Additionally, the default measurement interval for all sub-TLVs 649 should be 30 seconds. 651 Announcements must also be able to be throttled using configurable 652 inter-update throttle timers. The minimum announcement periodicity is 653 1 announcement per second. The default value should be set to 120 654 seconds. 656 Implementations should not permit the inter-update timer to be lower 657 than the measurement interval. 659 Furthermore, it is recommended that any underlying performance 660 measurement mechanisms not include any significant buffer delay, any 661 significant buffer induced delay variation, or any significant 662 loss due to buffer overflow or due to active queue management. 664 8. Enabling and Disabling Sub-TLVs 666 Implementations MUST make it possible to individually enable or 667 disable the advertisement of each sub-TLV. 669 9. Static Metric Override 671 Implementations SHOULD permit the static configuration and/or manual 672 override of dynamic measurements for each sub-TLV in order to 673 simplify migration and to mitigate scenarios where dynamic 674 measurements are not possible. 676 10. Compatibility 678 As per [RFC3630], an unrecognized TLV should be silently ignored. 679 I.e., it should not be processed but it should be included in LSAs 680 sent to OSPF neighbors. 682 11. Security Considerations 684 This document does not introduce security issues beyond those 685 discussed in [RFC3630]. OSPFv2 HMAC-SHA [RFC5709] provides 686 additional protection for OSPFv2. OSPFv3 IPsec [RFC4552] and OSPFv3 687 Authentication Trailer [RFC7166] provide additional protection for 688 OSPFv3. 690 OSPF KARP [RFC6863] provides an analysis of OSPFv2 and OSPFv3 routing 691 security and OSPFv2 Security Extensions [OSPFSEC] provides extensions 692 designed to address the identified gaps in OSPFv2. 694 12. IANA Considerations 696 IANA maintains the registry for the Link TLV sub-TLVs. OSPF TE Metric 697 Extensions will require one new type code for each sub-TLV defined in 698 this document, as follows: 700 Type Description 702 TBD1 Unidirectional Link Delay 704 TBD2 Min/Max Unidirectional Link Delay 706 TBD3 Unidirectional Delay Variation 708 TBD4 Unidirectional Link Loss 710 TBD5 Unidirectional Residual Bandwidth 712 TBD6 Unidirectional Available Bandwidth 714 TBD7 Unidirectional Utilized Bandwidth 716 13. References 718 13.1. Normative References 720 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 721 Requirement Levels", BCP 14, RFC 2119, March 1997. 723 [RFC3630] Katz, D., Kompella, K., Yeung, D., "Traffic 724 Engineering (TE) Extensions to OSPF Version 2", RFC 3630, 725 September 2003. 727 [RFC5329] Ishiguro, K., Manral, V., Davey, A., Lindem, A., "Traffic 728 Engineering Extensions to OSPF Version 3", RFC 5329, 729 September 2009. 731 [IEEE754] Institute of Electrical and Electronics Engineers, 732 "Standard for Floating-Point Arithmetic", IEEE Standard 733 754, August 2008. 735 13.2. Informative References 737 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, 738 V., Swallow, G., "RSVP-TE: Extensions to RSVP for LSP 739 Tunnels", RFC 3209, December 2001. 741 [RFC4206] Kompella, K., Rekhter, Y., "Label Switched Paths (LSP) 742 Hierarchy with Generalized Multi-Protocol Label Switching 743 (GMPLS) Traffic Engineering (TE)", RFC 4206, October 2005. 745 [RFC4552] Gupta, M., Melam, M., "Authentication/Confidentiality for 746 OSPFv3", RFC 4552, June 2006. 748 [RFC4655] Farrel, A., Vasseur, J.-P., Ash, J., "A Path Computation 749 Element (PCE)-Based Architecture", RFC 4655, August 2006. 751 [RFC5250] Berger, L., Bryskin I., Zinin, A., Coltun, R., "The OSPF 752 Opaque LSA Option", RFC 5250, July 2008. 754 [RFC5709] Bhatia, M., Manral, V., Fanto, M., White, R., Barnes, M., 755 Li, T., Atkinson, R., "OSPFv2 HMAC-SHA Cryptographic 756 Authentication", RFC 5709, October 2009. 758 [RFC6374] Frost, D., Bryant, S., "Packet Loss and Delay 759 Measurement for MPLS Networks", RFC 6374, September 2011. 761 [RFC6863] Hartman, S., Zhang, D., "Analysis of OSPF Security 762 According to the Keying and Authentication for Routing 763 Protocols (KARP) Design Guide", RFC 6863, March 2013. 765 [RFC7166] Bhatia, M., Manral, V., Lindem, A., "Supporting 766 Authentication Trailer for OSPFv3", RFC 7166, March 2014. 768 [RFC7285] Almi, R., Penno, R., Yang, Y., Kiesel, S., Previdi, S., 769 Roome, W., Shalunov, S., Woundy, R., "Application-Layer 770 Traffic Optimization (ALTO) Protocol", RFC 7285, September 771 2014. 773 [OSPFSEC] Bhatia, M., Hartman, S., Zhang, D., Lindem, A., "Security 774 Extensions for OSPFv2 when using Manual Key Management", 775 draft-ietf-ospf-security-extension-manual-keying, Work in 776 Progress. 778 14. Acknowledgments 780 The authors would like to recognize Nabil Bitar, Edward Crabbe, Don 781 Fedyk, Acee Lindem, David McDysan, and Ayman Soliman for their 782 contributions to this document. 784 The authors would also like to acknowledge Curtis Villamizar for his 785 significant comments and direct content collaboration. 787 This document was prepared using 2-Word-v2.0.template.dot. 789 15. Author's Addresses 791 Spencer Giacalone 792 Unaffiliated 794 Email: spencer.giacalone@gmail.com 796 Dave Ward 797 Cisco Systems 798 170 West Tasman Dr. 799 San Jose, CA 95134, USA 801 Email: dward@cisco.com 803 John Drake 804 Juniper Networks 805 1194 N. Mathilda Ave. 806 Sunnyvale, CA 94089, USA 808 Email: jdrake@juniper.net 810 Alia Atlas 811 Juniper Networks 812 1194 N. Mathilda Ave. 813 Sunnyvale, CA 94089, USA 815 Email: akatlas@juniper.net 817 Stefano Previdi 818 Cisco Systems 819 Via Del Serafico 200 820 00142 Rome 821 Italy 823 Email: sprevidi@cisco.com