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Giacalone 2 Internet Draft Thomson Reuters 3 Intended status: Proposed Standard 4 Expires: August 2013 D. Ward 5 Cisco Systems 7 J. Drake 8 Juniper Networks 10 A. Atlas 11 Juniper Networks 13 S. Previdi 14 Cisco Systems 16 February 25, 2013 18 OSPF Traffic Engineering (TE) Metric Extensions 19 draft-ietf-ospf-te-metric-extensions-03.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 August 25, 2013. 62 Copyright Notice 64 Copyright (c) 2012 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...................................................3 80 2. Conventions used in this document..............................4 81 3. TE Metric Extensions to OSPF TE................................5 82 4. Sub TLV Details................................................6 83 4.1. Unidirectional Link Delay Sub-TLV.........................6 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..........................................7 89 4.2. Unidirectional Delay Variation Sub-TLV....................7 90 4.2.1. Type.................................................8 91 4.2.2. Length...............................................8 92 4.2.3. Reserved.............................................8 93 4.2.4. Delay Variation......................................8 94 4.3. Unidirectional Link Loss Sub-TLV..........................8 95 4.3.1. Type.................................................8 96 4.3.2. Length...............................................9 97 4.3.3. A bit................................................9 98 4.3.4. Reserved.............................................9 99 4.3.5. Link Loss............................................9 100 4.4. Unidirectional Residual Bandwidth Sub-TLV.................9 101 4.4.1. Type................................................10 102 4.4.2. Length..............................................10 103 4.4.3. Residual Bandwidth..................................10 104 4.5. Unidirectional Available Bandwidth Sub-TLV...............10 105 4.4.4. Type................................................11 106 4.4.5. Length..............................................11 107 4.4.6. Available Bandwidth.................................11 108 5. Announcement Thresholds and Filters...........................11 109 6. Announcement Suppression......................................12 110 7. Network Stability and Announcement Periodicity................12 111 8. Compatibility.................................................12 112 9. Security Considerations.......................................12 113 10. IANA Considerations..........................................12 114 11. References...................................................13 115 11.1. Normative References....................................13 116 11.2. Informative References..................................13 117 12. Acknowledgments..............................................13 118 13. Author's Addresses...........................................14 120 1. Introduction 122 In certain networks, such as, but not limited to, financial 123 information networks (e.g. stock market data providers), network 124 performance information (e.g. latency) is becoming as critical to 125 data path selection as other metrics. 127 In these networks, extremely large amounts of money rest on the 128 ability to access market data in "real time" and to predictably make 129 trades faster than the competition. Because of this, using metrics 130 such as hop count or cost as routing metrics is becoming only 131 tangentially important. Rather, it would be beneficial to be able to 132 make path selection decisions based on performance data (such as 133 latency) in a cost-effective and scalable way. 135 This document describes extensions to OSPF TE (hereafter called "OSPF 136 TE Metric Extensions"), that can be used to distribute network 137 performance information (such as link delay, delay variation, packet 138 loss, residual bandwidth, and available bandwidth). 140 The data distributed by OSPF TE Metric Extensions is meant to be used 141 as part of the operation of the routing protocol (e.g. by replacing 142 cost with latency or considering bandwidth as well as cost), by 143 enhancing CSPF, or for other uses such as supplementing the data used 144 by an Alto server [Alto]. With respect to CSPF, the data distributed 145 by OSPF TE Metric Extensions can be used to setup, fail over, and 146 fail back data paths using protocols such as RSVP-TE [RFC3209]. 148 Note that the mechanisms described in this document only disseminate 149 performance information. The methods for initially gathering that 150 performance information, such as [RFC6375], or acting on it once it 151 is distributed are outside the scope of this document. Example 152 mechanisms to measure latency, delay variation, and loss in an MPLS 153 network are given in [RFC6374]. While this document does not 154 specify how the performance information should be obtained, the 155 measurement of delay SHOULD NOT vary significantly based upon the 156 offered traffic load. Thus, queuing delays SHOULD NOT be included 157 in the delay measurement. For links, such as Forwarding 158 Adjacencies, care must be taken that measurement of the associated 159 delay avoids significant queuing delay; that could be accomplished 160 in a variety of ways, including either by measuring with a traffic 161 class that experiences minimal queuing or by summing the measured 162 link delays of the components of the link's path. 164 2. Conventions used in this document 166 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 167 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 168 document are to be interpreted as described in RFC-2119 [RFC2119]. 170 In this document, these words will appear with that interpretation 171 only when in ALL CAPS. Lower case uses of these words are not to be 172 interpreted as carrying RFC-2119 significance. 174 3. TE Metric Extensions to OSPF TE 176 This document proposes new OSPF TE sub-TLVs that can be announced in 177 OSPF TE LSAs to distribute network performance information. The 178 extensions in this document build on the ones provided in OSPF TE 179 [RFC3630] and GMPLS [RFC4203]. 181 OSPF TE LSAs [RFC3630] are opaque LSAs [RFC5250] with area flooding 182 scope. Each TLV has one or more nested sub-TLVs which permit the TE 183 LSA to be readily extended. There are two main types of OSPF TE LSA; 184 the Router Address or Link TE LSA. Like the extensions in GMPLS 185 (RFC4203), this document proposes several additional sub-TLVs for 186 the Link TE LSA: 188 Type Length Value 190 TBD1 4 Unidirectional Link Delay 192 TBD2 4 Unidirectional Delay Variation 194 TBD3 4 Unidirectional Packet Loss 196 TBD4 4 Unidirectional Residual Bandwidth 198 TBD5 4 Unidirectional Available Bandwidth 200 As can be seen in the list above, the sub-TLVs described in this 201 document carry different types of network performance information. 202 Many (but not all) of the sub-TLVs include a bit called the Anomalous 203 (or "A") bit. When the A bit is clear (or when the sub-TLV does not 204 include an A bit), the sub-TLV describes steady state link 205 performance. This information could conceivably be used to construct 206 a steady state performance topology for initial tunnel path 207 computation, or to verify alternative failover paths. 209 When network performance violates configurable link-local thresholds 210 a sub-TLV with the A bit set is advertised. These sub-TLVs could be 211 used by the receiving node to determine whether to fail traffic to a 212 backup path, or whether to calculate an entirely new path. From an 213 MPLS perspective, the intent of the A bit is to permit LSP ingress 214 nodes to: 216 A) Determine whether the link referenced in the sub-TLV affects any 217 of the LSPs for which it is ingress. If there are, then: 219 B) The node determines whether those LSPs still meet end-to-end 220 performance objectives. If not, then: 222 C) The node could then conceivably move affected traffic to a pre- 223 established protection LSP or establish a new LSP and place the 224 traffic in it. 226 If link performance then improves beyond a configurable minimum 227 value (reuse threshold), that sub-TLV can be re-advertised with the 228 Anomalous bit cleared. In this case, a receiving node can 229 conceivably do whatever re-optimization (or failback) it wishes to 230 do (including nothing). 232 Note that when a sub-TLV does not include the A bit, that sub-TLV 233 cannot be used for failover purposes. The A bit was intentionally 234 omitted from some sub-TLVs to help mitigate oscillations. See section 235 7. 1. for more information. 237 Consistent with existing OSPF TE specifications (RFC3630), the 238 bandwidth advertisements defined in this draft MUST be encoded as 239 IEEE floating point values. The delay and delay variation 240 advertisements defined in this draft MUST be encoded as integer 241 values. Delay values MUST be quantified in units of microseconds, 242 packet loss MUST be quantified as a percentage of packets sent, and 243 bandwidth MUST be sent as bytes per second. All values (except 244 residual bandwidth) MUST be calculated as rolling averages where the 245 averaging period MUST be a configurable period of time. See section 246 5. for more information. 248 4. Sub TLV Details 250 4.1. Unidirectional Link Delay Sub-TLV 252 This sub-TLV advertises the average link delay between two directly 253 connected OSPF neighbors. The delay advertised by this sub-TLV MUST 254 be the delay from the local neighbor to the remote one (i.e. the 255 forward path latency). The format of this sub-TLV is shown in the 256 following diagram: 258 0 1 2 3 259 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 1 260 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 261 | TBD1 | 4 | 262 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 263 |A| RESERVED | Delay | 264 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 266 4.1.1. Type 268 This sub-TLV has a type of TBD1. 270 4.1.2. Length 272 The length is 4. 274 4.1.3. A bit 276 This field represents the Anomalous (A) bit. The A bit is set when 277 the measured value of this parameter exceeds its configured maximum 278 threshold. The A bit is cleared when the measured value falls below 279 its configured reuse threshold. If the A bit is clear, the sub-TLV 280 represents steady state link performance. 282 4.1.4. Reserved 284 This field is reserved for future use. It MUST be set to 0 when sent 285 and MUST be ignored when received. 287 4.1.5. Delay Value 289 This 24-bit field carries the average link delay over a configurable 290 interval in micro-seconds, encoded as an integer value. When set to 291 0, it has not been measured. When set to the maximum value 16,777,215 292 (16.777215 sec), then the delay is at least that value and may be 293 larger. 295 4.2. Unidirectional Delay Variation Sub-TLV 297 This sub-TLV advertises the average link delay variation between two 298 directly connected OSPF neighbors. The delay variation advertised by 299 this sub-TLV MUST be the delay from the local neighbor to the remote 300 one (i.e. the forward path latency). The format of this sub-TLV is 301 shown in the following diagram: 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 | TBD2 | 4 | 307 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 308 | RESERVED | Delay Variation | 309 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 311 4.2.1. Type 313 This sub-TLV has a type of TBD2. 315 4.2.2. Length 317 The length is 4. 319 4.2.3. Reserved 321 This field is reserved for future use. It MUST be set to 0 when sent 322 and MUST be ignored when received. 324 4.2.4. Delay Variation 326 This 24-bit field carries the average link delay variation over a 327 configurable interval in micro-seconds, encoded as an integer value. 328 When set to 0, it has not been measured. When set to the maximum 329 value 16,777,215 (16.777215 sec), then the delay is at least that 330 value and may be larger. 332 4.3. Unidirectional Link Loss Sub-TLV 334 This sub-TLV advertises the loss (as a packet percentage) between two 335 directly connected OSPF neighbors. The link loss advertised by this 336 sub-TLV MUST be the packet loss from the local neighbor to the remote 337 one (i.e. the forward path loss). The format of this sub-TLV is shown 338 in the following diagram: 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 | TBD3 | 4 | 344 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 345 |A| RESERVED | Link Loss | 346 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 348 4.3.1. Type 350 This sub-TLV has a type of TBD3 352 4.3.2. Length 354 The length is 4 356 4.3.3. A bit 358 This field represents the Anomalous (A) bit. The A bit is set when 359 the measured value of this parameter exceeds its configured maximum 360 threshold. The A bit is cleared when the measured value falls below 361 its configured reuse threshold. If the A bit is clear, the sub-TLV 362 represents steady state link performance. 364 4.3.4. Reserved 366 This field is reserved for future use. It MUST be set to 0 when sent 367 and MUST be ignored when received. 369 4.3.5. Link Loss 371 This 24-bit field carries link packet loss as a percentage of the 372 total traffic sent over a configurable interval. The basic unit is 373 0.000003%, where (2^24 - 2) is 50.331642%. This value is the highest 374 packet loss percentage that can be expressed (the assumption being 375 that precision is more important on high speed links than the ability 376 to advertise loss rates greater than this, and that high speed links 377 with over 50% loss are unusable). Therefore, measured values that are 378 larger than the field maximum SHOULD be encoded as the maximum value. 379 When set to a value of all 1s (2^24 - 1), the link packet loss has 380 not been measured. 382 4.4. Unidirectional Residual Bandwidth Sub-TLV 384 This TLV advertises the residual bandwidth (defined in section 4.4.3. 385 between two directly connected OSPF neighbors. The residual bandwidth 386 advertised by this sub-TLV MUST be the residual bandwidth from the 387 system originating the LSA to its neighbor. 389 The format of this 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 | TBD4 | 4 | 395 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 396 | Residual Bandwidth | 397 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 399 4.4.1. Type 401 This sub-TLV has a type of TBD4. 403 4.4.2. Length 405 The length is 4. 407 4.4.3. Residual Bandwidth 409 This field carries the residual bandwidth on a link, forwarding 410 adjacency [RFC4206], or bundled link in IEEE floating point format 411 with units of bytes per second. For a link or forwarding adjacency, 412 residual bandwidth is defined to be Maximum Bandwidth [RFC3630] minus 413 the bandwidth currently allocated to RSVP-TE LSPs. For a bundled 414 link, residual bandwidth is defined to be the sum of the component 415 link residual bandwidths. 417 Note that although it may seem possible to calculate Residual 418 Bandwidth using the existing sub-TLVs in RFC 3630, this is not a 419 consistently reliable approach and hence the Residual Bandwidth sub- 420 TLV has been added here. For example, because the Maximum Reservable 421 Bandwidth [RFC3630] can be larger than the capacity of the link, 422 using it as part of an algorithm to determine the value of the 423 Maximum Bandwidth [RFC3630] minus the bandwidth currently allocated 424 to RSVP-TE LSPs cannot be considered reliably accurate. 426 4.5. Unidirectional Available Bandwidth Sub-TLV 428 This TLV advertises the available bandwidth (defined in section 429 4.4.6. ) between two directly connected OSPF neighbors. The available 430 bandwidth advertised by this sub-TLV MUST be the available bandwidth 431 from the system originating the LSA to its neighbor. The format of 432 this sub-TLV is shown in the following diagram: 434 0 1 2 3 435 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 1 436 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 437 | TBD5 | 4 | 438 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 439 | Available Bandwidth | 440 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 442 4.4.4. Type 444 This sub-TLV has a type of TBD5. 446 4.4.5. Length 448 The length is 4. 450 4.4.6. Available Bandwidth 452 This field carries the available bandwidth on a link, forwarding 453 adjacency, or bundled link in IEEE floating point format with units 454 of bytes per second. For a link or forwarding adjacency, available 455 bandwidth is defined to be residual bandwidth (see section 4.4. ) 456 minus the measured bandwidth used for the actual forwarding of non- 457 RSVP-TE LSP packets. For a bundled link, available bandwidth is 458 defined to be the sum of the component link available bandwidths. 460 5. Announcement Thresholds and Filters 462 The values advertised in all sub-TLVs MUST be controlled using an 463 exponential filter (i.e. a rolling average) with a configurable 464 measurement interval and filter coefficient. 466 Implementations are expected to provide separately configurable 467 advertisement thresholds. All thresholds MUST be configurable on a 468 per sub-TLV basis. 470 The announcement of all sub-TLVs that do not include the A bit SHOULD 471 be controlled by variation thresholds that govern when they are sent. 473 Sub-TLV that include the A bit are governed by several thresholds. 474 Firstly, a threshold SHOULD be implemented to govern the announcement 475 of sub-TLVs that advertise a change in performance, but not an SLA 476 violation (i.e. when the A bit is not set). Secondly, implementations 477 MUST provide configurable thresholds that govern the announcement of 478 sub-TLVs with the A bit set (for the indication of a performance 479 violation). Thirdly, implementations SHOULD provide reuse 480 thresholds. This threshold governs sub-TLV re-announcement with the A 481 bit cleared to permit fail back. 483 6. Announcement Suppression 485 When link performance average values change, but fall under the 486 threshold that would cause the announcement of a sub-TLV with the A 487 bit set, implementations MAY suppress or throttle sub-TLV 488 announcements. All suppression features and thresholds SHOULD be 489 configurable. 491 7. Network Stability and Announcement Periodicity 493 To mitigate concerns about stability, all values (except residual 494 bandwidth) MUST be calculated as rolling averages where the averaging 495 period MUST be a configurable period of time, rather than 496 instantaneous measurements. 498 Announcements MUST also be able to be throttled using configurable 499 inter-update throttle timers. The minimum announcement periodicity is 500 1 announcement per second. 502 8. Compatibility 504 As per (RFC3630), unrecognized TLVs should be silently ignored 506 9. Security Considerations 508 This document does not introduce security issues beyond those 509 discussed in [RFC3630] and [RFC5329]. 511 10. IANA Considerations 513 IANA maintains the registry for the sub-TLVs. OSPF TE Metric 514 Extensions will require one new type code per sub-TLV defined in this 515 document. 517 11. References 519 11.1. Normative References 521 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 522 Requirement Levels", BCP 14, RFC 2119, March 1997. 524 [RFC3630] Katz, D., Kompella, K., Yeung, D., "Traffic 525 Engineering (TE) Extensions to OSPF Version 2", RFC 3630, 526 September 2003. 528 [RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay 529 Measurement for MPLS Networks", RFC 6374, September 2011. 531 11.2. Informative References 533 [RFC2328] Moy, J, "OSPF Version 2", RFC 2328, April 1998 535 [RFC3031] Rosen, E., Viswanathan, A., Callon, R., "Multiprotocol 536 Label Switching Architecture", January 2001 538 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, 539 V., and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP 540 Tunnels", RFC 3209, December 2001. 542 [RFC5250] Berger, L., Bryskin I., Zinin, A., Coltun, R., "The OSPF 543 Opaque LSA Option", RFC 5250, July 2008. 545 [RFC6375] Frost, D. and S. Bryant, "A Packet Loss and Delay 546 Measurement Profile for MPLS-Based Transport Networks", 547 RFC 6375, September 2011. 549 [Alto] R. Alimi R. Penno Y. Yang, "ALTO Protocol" 551 12. Acknowledgments 553 The authors would like to recognize Ayman Soliman for his 554 contributions. 556 This document was prepared using 2-Word-v2.0.template.dot. 558 13. Author's Addresses 560 Spencer Giacalone 561 Thomson Reuters 562 195 Broadway 563 New York, NY 10007, USA 565 Email: Spencer.giacalone@thomsonreuters.com 567 Dave Ward 568 Cisco Systems 569 170 West Tasman Dr. 570 San Jose, CA 95134, USA 572 Email: dward@cisco.com 574 John Drake 575 Juniper Networks 576 1194 N. Mathilda Ave. 577 Sunnyvale, CA 94089, USA 579 Email: jdrake@juniper.net 581 Alia Atlas 582 Juniper Networks 583 1194 N. Mathilda Ave. 584 Sunnyvale, CA 94089, USA 586 Email: akatlas@juniper.net 588 Stefano Previdi 589 Cisco Systems 590 Via Del Serafico 200 591 00142 Rome 592 Italy 594 Email: sprevidi@cisco.com