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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 Network Working Group S. Giacalone 2 Internet Draft Thomson Reuters 3 Intended status: Proposed Standard 4 Expires: June 2014 D. Ward 5 Cisco Systems 7 J. Drake 8 Juniper Networks 10 A. Atlas 11 Juniper Networks 13 S. Previdi 14 Cisco Systems 16 December 5, 2013 18 OSPF Traffic Engineering (TE) Metric Extensions 19 draft-ietf-ospf-te-metric-extensions-05.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 criteria (e.g. latency) are becoming as critical to data 26 path selection as other metrics. 28 This document describes extensions to OSPF TE [RFC3630] such that 29 network performance information can be distributed and collected in a 30 scalable fashion. The information distributed using OSPF TE Metric 31 Extensions can then be used to make path selection decisions based on 32 network performance. 34 Note that this document only covers the mechanisms with which network 35 performance information is distributed. The mechanisms for measuring 36 network performance or acting on that information, once distributed, 37 are outside the scope of this document. 39 Status of this Memo 41 This Internet-Draft is submitted in full conformance with the 42 provisions of BCP 78 and BCP 79. 44 Internet-Drafts are working documents of the Internet Engineering 45 Task Force (IETF), its areas, and its working groups. Note that 46 other groups may also distribute working documents as Internet- 47 Drafts. 49 Internet-Drafts are draft documents valid for a maximum of six months 50 and may be updated, replaced, or obsoleted by other documents at any 51 time. It is inappropriate to use Internet-Drafts as reference 52 material or to cite them other than as "work in progress." 54 The list of current Internet-Drafts can be accessed at 55 http://www.ietf.org/ietf/1id-abstracts.txt 57 The list of Internet-Draft Shadow Directories can be accessed at 58 http://www.ietf.org/shadow.html 60 This Internet-Draft will expire on May 5, 2014. 62 Copyright Notice 64 Copyright (c) 2013 IETF Trust and the persons identified as the 65 document authors. All rights reserved. 67 This document is subject to BCP 78 and the IETF Trust's Legal 68 Provisions Relating to IETF Documents 69 (http://trustee.ietf.org/license-info) in effect on the date of 70 publication of this document. Please review these documents 71 carefully, as they describe your rights and restrictions with respect 72 to this document. Code Components extracted from this document must 73 include Simplified BSD License text as described in Section 4.e of 74 the Trust Legal Provisions and are provided without warranty as 75 described in the Simplified BSD License. 77 Table of Contents 79 1. Introduction...................................................4 80 2. Conventions used in this document..............................5 81 3. TE Metric Extensions to OSPF TE................................5 82 4. Sub TLV Details................................................7 83 4.1. Unidirectional Link Delay Sub-TLV.........................7 84 4.1.1. Type.................................................7 85 4.1.2. Length...............................................7 86 4.1.3. A bit................................................7 87 4.1.4. Reserved.............................................7 88 4.1.5. Delay Value..........................................8 89 4.2. Min/Max Unidirectional Link Delay Sub-TLV.................8 90 4.2.1. Type.................................................8 91 4.2.2. Length...............................................8 92 4.2.3. A bit................................................8 93 4.2.4. Reserved.............................................9 94 4.2.5. Low Delay............................................9 95 4.2.6. High Delay...........................................9 96 4.2.7. Reserved.............................................9 97 4.3. Unidirectional Delay Variation Sub-TLV...................10 98 4.3.1. Type................................................10 99 4.3.2. Length..............................................10 100 4.3.3. Reserved............................................10 101 4.3.4. Delay Variation.....................................10 102 4.4. Unidirectional Link Loss Sub-TLV.........................10 103 4.4.1. Type................................................11 104 4.4.2. Length..............................................11 105 4.4.3. A bit...............................................11 106 4.4.4. Reserved............................................11 107 4.4.5. Link Loss...........................................11 108 4.5. Unidirectional Residual Bandwidth Sub-TLV................12 109 4.5.1. Type................................................12 110 4.5.2. Length..............................................12 111 4.5.3. Residual Bandwidth..................................12 112 4.6. Unidirectional Available Bandwidth Sub-TLV...............13 113 4.6.1. Type................................................13 114 4.6.2. Length..............................................13 115 4.6.3. Available Bandwidth.................................13 116 4.7. Unidirectional Utilized Bandwidth Sub-TLV................13 117 4.7.1. Type................................................14 118 4.7.2. Length..............................................14 119 4.7.3. Utilized Bandwidth..................................14 120 5. Announcement Thresholds and Filters...........................14 121 6. Announcement Suppression......................................15 122 7. Network Stability and Announcement Periodicity................16 123 8. Enabling and Disabling Sub-TLVs...............................16 124 9. Static Metric Override........................................16 125 10. Compatibility................................................17 126 11. Security Considerations......................................17 127 12. IANA Considerations..........................................17 128 13. References...................................................17 129 13.1. Normative References....................................17 130 13.2. Informative References..................................17 131 14. Acknowledgments..............................................18 132 15. Author's Addresses...........................................18 134 1. Introduction 136 In certain networks, such as, but not limited to, financial 137 information networks (e.g. stock market data providers), network 138 performance information (e.g. latency) is becoming as critical to 139 data path selection as other metrics. 141 In these networks, extremely large amounts of money rest on the 142 ability to access market data in "real time" and to predictably make 143 trades faster than the competition. Because of this, using metrics 144 such as hop count or cost as routing metrics is becoming only 145 tangentially important. Rather, it would be beneficial to be able to 146 make path selection decisions based on performance data (such as 147 latency) in a cost-effective and scalable way. 149 This document describes extensions to OSPF TE (hereafter called "OSPF 150 TE Metric Extensions"), that can be used to distribute network 151 performance information (such as link delay, delay variation, packet 152 loss, residual bandwidth, and available 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 latency or considering bandwidth as well as cost), by 157 enhancing CSPF, or for other uses such as supplementing the data used 158 by an Alto server [Alto]. With respect to CSPF, the data distributed 159 by OSPF TE Metric Extensions can be used to setup, fail over, and 160 fail back data paths using protocols such as RSVP-TE [RFC3209].[ 161 Draft-ietf-mpls-te-express-path] describes some methods for using 162 this information to compute Label Switched Paths (LSPs) at the LSP 163 ingress. 165 Note that the mechanisms described in this document only disseminate 166 performance information. The methods for initially gathering that 167 performance information, such as [RFC6375], or acting on it once it 168 is distributed are outside the scope of this document. Example 169 mechanisms to measure latency, delay variation, and loss in an MPLS 170 network are given in [RFC6374]. While this document does not 171 specify how the performance information should be obtained, the 172 measurement of delay SHOULD NOT vary significantly based upon the 173 offered traffic load. Thus, queuing delays and/or loss SHOULD NOT 174 be included in any dynamic delay measurement. For links, such as 175 Forwarding Adjacencies, care must be taken that measurement of the 176 associated delay avoids significant queuing delay; that could be 177 accomplished in a variety of ways, including either by measuring 178 with a traffic class that experiences minimal queuing or by summing 179 the measured link delays of the components of the link's path. 181 2. Conventions used in this document 183 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 184 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 185 document are to be interpreted as described in RFC-2119 [RFC2119]. 187 In this document, these words will appear with that interpretation 188 only when in ALL CAPS. Lower case uses of these words are not to be 189 interpreted as carrying RFC-2119 significance. 191 3. TE Metric Extensions to OSPF TE 193 This document proposes new OSPF TE sub-TLVs that can be announced in 194 OSPF TE LSAs to distribute network performance information. The 195 extensions in this document build on the ones provided in OSPF TE 196 [RFC3630] and GMPLS [RFC4203]. 198 OSPF TE LSAs [RFC3630] are opaque LSAs [RFC5250] with area flooding 199 scope. Each TLV has one or more nested sub-TLVs which permit the TE 200 LSA to be readily extended. There are two main types of OSPF TE LSA; 201 the Router Address or Link TE LSA. Like the extensions in GMPLS 202 (RFC4203), this document proposes several additional sub-TLVs for 203 the Link TE LSA: 205 Type Length Value 207 TBD1 4 Unidirectional Link Delay 209 TBD2 8 Low/High Unidirectional Link Delay 211 TBD3 4 Unidirectional Delay Variation 213 TBD4 4 Unidirectional Packet Loss 215 TBD5 4 Unidirectional Residual Bandwidth 217 TBD6 4 Unidirectional Available Bandwidth 218 TBD7 4 Unidirectional Utilized Bandwidth 220 As can be seen in the list above, the sub-TLVs described in this 221 document carry different types of network performance information. 222 Many (but not all) of the sub-TLVs include a bit called the Anomalous 223 (or "A") bit. When the A bit is clear (or when the sub-TLV does not 224 include an A bit), the sub-TLV describes steady state link 225 performance. This information could conceivably be used to construct 226 a steady state performance topology for initial tunnel path 227 computation, or to verify alternative failover paths. 229 When network performance violates configurable link-local thresholds 230 a sub-TLV with the A bit set is advertised. These sub-TLVs could be 231 used by the receiving node to determine whether to fail traffic to a 232 backup path, or whether to calculate an entirely new path. From an 233 MPLS perspective, the intent of the A bit is to permit LSP ingress 234 nodes to: 236 A) Determine whether the link referenced in the sub-TLV affects any 237 of the LSPs for which it is ingress. If there are, then: 239 B) The node determines whether those LSPs still meet end-to-end 240 performance objectives. If not, then: 242 C) The node could then conceivably move affected traffic to a pre- 243 established protection LSP or establish a new LSP and place the 244 traffic in it. 246 If link performance then improves beyond a configurable minimum 247 value (reuse threshold), that sub-TLV can be re-advertised with the 248 Anomalous bit cleared. In this case, a receiving node can 249 conceivably do whatever re-optimization (or failback) it wishes to 250 do (including nothing). 252 Note that when a sub-TLV does not include the A bit, that sub-TLV 253 cannot be used for failover purposes. The A bit was intentionally 254 omitted from some sub-TLVs to help mitigate oscillations. See section 255 7. 1. for more information. 257 Consistent with existing OSPF TE specifications (RFC3630), the 258 bandwidth advertisements defined in this draft MUST be encoded as 259 IEEE floating point values. The delay and delay variation 260 advertisements defined in this draft MUST be encoded as integer 261 values. Delay values MUST be quantified in units of microseconds, 262 packet loss MUST be quantified as a percentage of packets sent, and 263 bandwidth MUST be sent as bytes per second. All values (except 264 residual bandwidth) MUST be calculated as rolling averages where the 265 averaging period MUST be a configurable period of time. See section 266 5. for more information. 268 4. Sub TLV Details 270 4.1. Unidirectional Link Delay Sub-TLV 272 This sub-TLV advertises the average link delay between two directly 273 connected OSPF neighbors. The delay advertised by this sub-TLV MUST 274 be the delay from the local neighbor to the remote one (i.e. the 275 forward path latency). The format of this sub-TLV is shown in the 276 following diagram: 278 0 1 2 3 279 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 1 280 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 281 | TBD1 | 4 | 282 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 283 |A| RESERVED | Delay | 284 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 286 4.1.1. Type 288 This sub-TLV has a type of TBD1. 290 4.1.2. Length 292 The length is 4. 294 4.1.3. A bit 296 This field represents the Anomalous (A) bit. The A bit is set when 297 the measured value of this parameter exceeds its configured maximum 298 threshold. The A bit is cleared when the measured value falls below 299 its configured reuse threshold. If the A bit is clear, the sub-TLV 300 represents steady state link performance. 302 4.1.4. Reserved 304 This field is reserved for future use. It MUST be set to 0 when sent 305 and MUST be ignored when received. 307 4.1.5. Delay Value 309 This 24-bit field carries the average link delay over a configurable 310 interval in micro-seconds, encoded as an integer value. When set to 311 the maximum value 16,777,215 (16.777215 sec), then the delay is at 312 least that value and may be larger. If there is no value to send 313 (unmeasured and not statically specified), then the sub-TLV should 314 not be sent or be withdrawn. 316 4.2. Min/Max Unidirectional Link Delay Sub-TLV 318 This sub-TLV advertises the minimum and maximum delay values between 319 two directly connected OSPF neighbors. The delay advertised by this 320 sub-TLV MUST be the delay from the local neighbor to the remote one 321 (i.e. the forward path latency). The format of this sub-TLV is shown 322 in the following diagram: 324 0 1 2 3 325 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 1 326 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 327 | TBD2 | 8 | 328 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 329 |A| RESERVED | Min Delay | 330 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 331 | RESERVED | Max Delay | 332 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 334 4.2.1. Type 336 This sub-TLV has a type of TBD2. 338 4.2.2. Length 340 The length is 8. 342 4.2.3. A bit 344 This field represents the Anomalous (A) bit. The A bit is set when 345 one or more measured values exceed a configured maximum threshold. 346 The A bit is cleared when the measured value falls below its 347 configured reuse threshold. If the A bit is clear, the sub-TLV 348 represents steady state link performance. 350 4.2.4. Reserved 352 This field is reserved for future use. It MUST be set to 0 when sent 353 and MUST be ignored when received. 355 4.2.5. Low Delay 357 This 24-bit field carries minimum measured link delay value (in 358 microseconds) over a configurable interval, encoded as an integer 359 value. 361 Implementations MAY also permit the configuration of a static (non 362 dynamic) offset value (in microseconds) to be added to the measured 363 delay value, to facilitate the communication of operator specific 364 delay constraints. 366 When set to the maximum value 16,777,215 (16.777215 sec), then the 367 delay is at least that value and may be larger. 369 4.2.6. High Delay 371 This 24-bit field carries the maximum measured link delay value (in 372 microseconds) over a configurable interval, encoded as an integer 373 value. 375 Implementations MAY also permit the configuration of a static (non 376 dynamic) offset value (in microseconds) to be added to the measured 377 delay value, to facilitate the communication of operator specific 378 delay constraints. 380 It is possible for the high delay and low delay to be the same value. 382 When the delay value is set to maximum value 16,777,215 (16.777215 383 sec), then the delay is at least that value and may be larger. 385 4.2.7. Reserved 387 This field is reserved for future use. It MUST be set to 0 when sent 388 and MUST be ignored when received. 390 When only an average delay value is sent, this field is not present 391 in the TLV. 393 4.3. Unidirectional Delay Variation Sub-TLV 395 This sub-TLV advertises the average link delay variation between two 396 directly connected OSPF neighbors. The delay variation advertised by 397 this sub-TLV MUST be the delay from the local neighbor to the remote 398 one (i.e. the forward path latency). The format of this sub-TLV is 399 shown in the following diagram: 401 0 1 2 3 402 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 1 403 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 404 | TBD3 | 4 | 405 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 406 | RESERVED | Delay Variation | 407 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 409 4.3.1. Type 411 This sub-TLV has a type of TBD3. 413 4.3.2. Length 415 The length is 4. 417 4.3.3. Reserved 419 This field is reserved for future use. It MUST be set to 0 when sent 420 and MUST be ignored when received. 422 4.3.4. Delay Variation 424 This 24-bit field carries the average link delay variation over a 425 configurable interval in micro-seconds, encoded as an integer value. 426 When set to 0, it has not been measured. When set to the maximum 427 value 16,777,215 (16.777215 sec), then the delay is at least that 428 value and may be larger. 430 4.4. Unidirectional Link Loss Sub-TLV 432 This sub-TLV advertises the loss (as a packet percentage) between two 433 directly connected OSPF neighbors. The link loss advertised by this 434 sub-TLV MUST be the packet loss from the local neighbor to the remote 435 one (i.e. the forward path loss). The format of this sub-TLV is shown 436 in the following diagram: 438 0 1 2 3 439 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 1 440 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 441 | TBD4 | 4 | 442 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 443 |A| RESERVED | Link Loss | 444 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 446 4.4.1. Type 448 This sub-TLV has a type of TBD4 450 4.4.2. Length 452 The length is 4. 454 4.4.3. A bit 456 This field represents the Anomalous (A) bit. The A bit is set when 457 the measured value of this parameter exceeds its configured maximum 458 threshold. The A bit is cleared when the measured value falls below 459 its configured reuse threshold. If the A bit is clear, the sub-TLV 460 represents steady state link performance. 462 4.4.4. Reserved 464 This field is reserved for future use. It MUST be set to 0 when sent 465 and MUST be ignored when received. 467 4.4.5. Link Loss 469 This 24-bit field carries link packet loss as a percentage of the 470 total traffic sent over a configurable interval. The basic unit is 471 0.000003%, where (2^24 - 2) is 50.331642%. This value is the highest 472 packet loss percentage that can be expressed (the assumption being 473 that precision is more important on high speed links than the ability 474 to advertise loss rates greater than this, and that high speed links 475 with over 50% loss are unusable). Therefore, measured values that are 476 larger than the field maximum SHOULD be encoded as the maximum value. 477 When set to a value of all 1s (2^24 - 1), the link packet loss has 478 not been measured. 480 4.5. Unidirectional Residual Bandwidth Sub-TLV 482 This sub-TLV advertises the residual bandwidth between two directly 483 connected OSPF neighbors. The residual bandwidth advertised by this 484 sub-TLV MUST be the residual bandwidth from the system originating 485 the LSA to its neighbor. 487 The format of this sub-TLV is shown in the following diagram: 489 0 1 2 3 490 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 1 491 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 492 | TBD5 | 4 | 493 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 494 | Residual Bandwidth | 495 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 497 4.5.1. Type 499 This sub-TLV has a type of TBD5. 501 4.5.2. Length 503 The length is 4. 505 4.5.3. Residual Bandwidth 507 This field carries the residual bandwidth on a link, forwarding 508 adjacency [RFC4206], or bundled link in IEEE floating point format 509 with units of bytes per second. For a link or forwarding adjacency, 510 residual bandwidth is defined to be Maximum Bandwidth [RFC3630] minus 511 the bandwidth currently allocated to RSVP-TE LSPs. For a bundled 512 link, residual bandwidth is defined to be the sum of the component 513 link residual bandwidths. 515 The calculation of Residual Bandwidth is different than that of 516 Unreserved Bandwidth [RFC3630]. Residual Bandwidth subtracts tunnel 517 reservations from Maximum Bandwidth (i.e. the link capacity) 518 [RFC3630] and provides an aggregated remainder across QoS classes. 519 Unreserved Bandwidth [RFC3630], on the other hand, is subtracted from 520 the Maximum Reservable Bandwidth (the bandwidth that can 521 theoretically be reserved) [RFC3630] and provides per-QoS-class 522 remainders. Residual Bandwidth and Unreserved Bandwidth [RFC3630] can 523 be used concurrently, and each has a separate use case (e.g. the 524 former can be used for applications like Weighted ECMP while the 525 latter can be used for call admission control). 527 4.6. Unidirectional Available Bandwidth Sub-TLV 529 This TLV advertises the available bandwidth between two directly 530 connected OSPF neighbors. The available bandwidth advertised by this 531 sub-TLV MUST be the available bandwidth from the system originating 532 the LSA to its neighbor. The format of this sub-TLV is shown in the 533 following diagram: 535 0 1 2 3 536 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 1 537 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 538 | TBD6 | 4 | 539 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 540 | Available Bandwidth | 541 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 543 4.6.1. Type 545 This sub-TLV has a type of TBD6. 547 4.6.2. Length 549 The length is 4. 551 4.6.3. Available Bandwidth 553 This field carries the available bandwidth on a link, forwarding 554 adjacency, or bundled link in IEEE floating point format with units 555 of bytes per second. For a link or forwarding adjacency, available 556 bandwidth is defined to be residual bandwidth (see section 4.5. ) 557 minus the measured bandwidth used for the actual forwarding of non- 558 RSVP-TE LSP packets. For a bundled link, available bandwidth is 559 defined to be the sum of the component link available bandwidths. 561 4.7. Unidirectional Utilized Bandwidth Sub-TLV 563 This Sub-TLV advertises the bandwidth utilization between two 564 directly connected OSPF neighbors. The bandwidth utilization 565 advertised by this sub-TLV MUST be the bandwidth from the system 566 originating this Sub-TLV. The format of this Sub-TLV is shown in the 567 following diagram: 569 0 1 2 3 570 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 1 571 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 572 | TBD7 | 4 | 573 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 574 | Utilized Bandwidth | 575 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 577 4.7.1. Type 579 This sub-TLV has a type of TBD7. 581 4.7.2. Length 583 The length is 4. 585 4.7.3. Utilized Bandwidth 587 This field carries the bandwidth utilization on a link, forwarding 588 adjacency, or bundled link in IEEE floating point format with units 589 of bytes per second. For a link or forwarding adjacency, bandwidth 590 utilization represents the actual utilization of the link (i.e. as 591 measured in the router). For a bundled link, bandwidth utilization is 592 defined to be the sum of the component link bandwidth utilizations. 594 5. Announcement Thresholds and Filters 596 The values advertised in all sub-TLVs (except min/max delay and 597 residual bandwidth) MUST represent an average over a period or be 598 obtained by a filter that is reasonably representative of an 599 average. For example, a rolling average is one such filter. 601 Low or high delay MAY be the lowest and/or highest measured value 602 over a measurement interval or MAY make use of a filter, or other 603 technique to obtain a reasonable representation of a low and high 604 value representative of the interval with compensation for outliers. 606 The measurement interval, any filter coefficients, and any 607 advertisement intervals MUST be configurable per sub-TLV. 609 In addition to the measurement intervals governing re-advertisement, 610 implementations SHOULD provide per sub-TLV configurable accelerated 611 advertisement thresholds, such that: 613 1. If the measured parameter falls outside a configured upper bound 614 for all but the min delay metric (or lower bound for min-delay 615 metric only) and the advertised sub-TLV is not already outside 616 that bound or, 618 2. If the difference between the last advertised value and current 619 measured value exceed a configured threshold then, 621 3. The advertisement is made immediately. 623 4. For sub-TLVs which include an A-bit (except low/high delay), an 624 additional threshold SHOULD be included corresponding to the 625 threshold for which the performance is considered anomalous (and 626 sub-TLVs with the A bit are sent). The A-bit is cleared when the 627 sub-TLV's performance has been below (or re-crosses) this 628 threshold for an advertisement interval(s) to permit fail back. 630 To prevent oscillations, only the high threshold or the low threshold 631 (but not both) may be used to trigger any given sub-TLV that supports 632 both. 634 Additionally, once outside of the bounds of the threshold, any 635 readvertisement of a measurement within the bounds would remain 636 governed solely by the measurement interval for that sub-TLV. 638 6. Announcement Suppression 640 When link performance values change by small amounts that fall under 641 thresholds that would cause the announcement of a sub-TLV, 642 implementations SHOULD suppress sub-TLV readvertisement and/or 643 lengthen the period within which they are refreshed. 645 Only the accelerated advertisement threshold mechanism described in 646 section 6 may shorten the re-advertisement interval. 648 All suppression and re-advertisement interval backoff timer features 649 SHOULD be configurable. 651 7. Network Stability and Announcement Periodicity 653 Sections 6 and 7 provide configurable mechanisms to bound the number 654 of re-advertisements. Instability might occur in very large networks 655 if measurement intervals are set low enough to overwhelm the 656 processing of flooded information at some of the routers in the 657 topology. Therefore care SHOULD be taken in setting these values. 659 Additionally, the default measurement interval for all sub-TLVs 660 SHOULD be 30 seconds. 662 Announcements MUST also be able to be throttled using configurable 663 inter-update throttle timers. The minimum announcement periodicity is 664 1 announcement per second. The default value SHOULD be set to 120 665 seconds. 667 Implementations SHOULD NOT permit the inter-update timer to be lower 668 than the measurement interval. 670 Furthermore, it is RECOMMENDED that any underlying performance 671 measurement mechanisms not include any significant buffer delay, any 672 significant buffer induced delay variation, or any significant 673 loss due to buffer overflow or due to active queue management. 675 8. Enabling and Disabling Sub-TLVs 677 Implementations MUST make it possible to individually enable or 678 disable each sub-TLV based on configuration. 680 9. Static Metric Override 682 Implementations SHOULD permit the static configuration and/or manual 683 override of dynamic measurements data on a per sub-TLV, per metric 684 basis in order to simplify migrations and to mitigate scenarios where 685 measurements are not possible across an entire network. 687 10. Compatibility 689 As per (RFC3630), unrecognized TLVs should be silently ignored 691 11. Security Considerations 693 This document does not introduce security issues beyond those 694 discussed in [RFC3630] and [RFC5329]. 696 12. IANA Considerations 698 IANA maintains the registry for the sub-TLVs. OSPF TE Metric 699 Extensions will require one new type code per sub-TLV defined in this 700 document. 702 13. References 704 13.1. Normative References 706 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 707 Requirement Levels", BCP 14, RFC 2119, March 1997. 709 [RFC3630] Katz, D., Kompella, K., Yeung, D., "Traffic 710 Engineering (TE) Extensions to OSPF Version 2", RFC 3630, 711 September 2003. 713 [RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay 714 Measurement for MPLS Networks", RFC 6374, September 2011. 716 13.2. Informative References 718 [RFC2328] Moy, J, "OSPF Version 2", RFC 2328, April 1998 720 [RFC3031] Rosen, E., Viswanathan, A., Callon, R., "Multiprotocol 721 Label Switching Architecture", January 2001 723 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, 724 V., and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP 725 Tunnels", RFC 3209, December 2001. 727 [RFC5250] Berger, L., Bryskin I., Zinin, A., Coltun, R., "The OSPF 728 Opaque LSA Option", RFC 5250, July 2008. 730 [RFC6375] Frost, D. and S. Bryant, "A Packet Loss and Delay 731 Measurement Profile for MPLS-Based Transport Networks", 732 RFC 6375, September 2011. 734 [Alto] R. Alimi R. Penno Y. Yang, "ALTO Protocol" 736 [Draft-ietf-mpls-te-express-path] Atlas, A., Drake, J., Giacalone, 737 S., Ward, D., Previdi, S., and C. Filsfils, "Performance- 738 based Path Selection for Explicitly Routed LSPs using TE 739 Metric Extensions", Draft-ietf-mpls-te-express-path (work 740 in progress), October 2013 742 14. Acknowledgments 744 The authors would like to recognize Ayman Soliman, Nabil Bitar, David 745 McDysan, Edward Crabbe, and Don Fedyk for their contributions. 747 The authors also recognize Curtis Villamizar for significant comments 748 and direct content collaboration. 750 This document was prepared using 2-Word-v2.0.template.dot. 752 15. Author's Addresses 754 Spencer Giacalone 755 Thomson Reuters 756 195 Broadway 757 New York, NY 10007, USA 759 Email: Spencer.giacalone@thomsonreuters.com 761 Dave Ward 762 Cisco Systems 763 170 West Tasman Dr. 765 San Jose, CA 95134, USA 767 Email: dward@cisco.com 769 John Drake 770 Juniper Networks 771 1194 N. Mathilda Ave. 772 Sunnyvale, CA 94089, USA 774 Email: jdrake@juniper.net 776 Alia Atlas 777 Juniper Networks 778 1194 N. Mathilda Ave. 779 Sunnyvale, CA 94089, USA 781 Email: akatlas@juniper.net 783 Stefano Previdi 784 Cisco Systems 785 Via Del Serafico 200 786 00142 Rome 787 Italy 789 Email: sprevidi@cisco.com