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Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (March 08, 2012) is 3726 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Downref: Normative reference to an Informational RFC: RFC 6375 == Outdated reference: draft-ietf-alto-protocol has been published as RFC 7285 Summary: 3 errors (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Networking Working Group S. Previdi, Ed. 3 Internet-Draft Cisco Systems, Inc. 4 Intended status: Standards Track S. Giacalone 5 Expires: September 9, 2012 Thomson Reuters 6 D. Ward 7 Cisco Systems, Inc. 8 J. Drake 9 A. Atlas 10 Juniper Networks 11 C. Filsfils 12 Cisco Systems, Inc. 13 March 08, 2012 15 IS-IS Traffic Engineering (TE) Metric Extensions 16 draft-previdi-isis-te-metric-extensions-01 18 Abstract 20 In certain networks, such as, but not limited to, financial 21 information networks (e.g. stock market data providers), network 22 performance criteria (e.g. latency) are becoming as critical to data 23 path selection as other metrics. 25 This document describes extensions to IS-IS TE [RFC5305] such that 26 network performance information can be distributed and collected in a 27 scalable fashion. The information distributed using ISIS TE Express 28 Path can then be used to make path selection decisions based on 29 network performance. 31 Note that this document only covers the mechanisms with which network 32 performance information is distributed. The mechanisms for measuring 33 network performance or acting on that information, once distributed, 34 are outside the scope of this document. 36 Requirements Language 38 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 39 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 40 document are to be interpreted as described in RFC 2119 [RFC2119]. 42 In this document, these words will appear with that interpretation 43 only when in ALL CAPS. Lower case uses of these words are not to be 44 interpreted as carrying RFC-2119 significance. 46 Status of this Memo 48 This Internet-Draft is submitted in full conformance with the 49 provisions of BCP 78 and BCP 79. 51 Internet-Drafts are working documents of the Internet Engineering 52 Task Force (IETF). Note that other groups may also distribute 53 working documents as Internet-Drafts. The list of current Internet- 54 Drafts is at http://datatracker.ietf.org/drafts/current/. 56 Internet-Drafts are draft documents valid for a maximum of six months 57 and may be updated, replaced, or obsoleted by other documents at any 58 time. It is inappropriate to use Internet-Drafts as reference 59 material or to cite them other than as "work in progress." 61 This Internet-Draft will expire on September 9, 2012. 63 Copyright Notice 65 Copyright (c) 2012 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. Express Path Extensions to IS-IS TE . . . . . . . . . . . . . 4 82 3. Sub TLV Details . . . . . . . . . . . . . . . . . . . . . . . 6 83 3.1. Unidirectional Link Delay Sub-TLV . . . . . . . . . . . . 6 84 3.2. Unidirectional Delay Variation Sub-TLV . . . . . . . . . . 7 85 3.3. Unidirectional Link Loss Sub-TLV . . . . . . . . . . . . . 7 86 3.4. Unidirectional Residual Bandwidth Sub-TLV . . . . . . . . 8 87 3.5. Unidirectional Available Bandwidth Sub-TLV . . . . . . . . 9 88 4. Announcement Thresholds and Filters . . . . . . . . . . . . . 10 89 5. Announcement Suppression . . . . . . . . . . . . . . . . . . . 11 90 6. Network Stability and Announcement Periodicity . . . . . . . . 11 91 7. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 11 92 8. Security Considerations . . . . . . . . . . . . . . . . . . . 11 93 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 94 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11 95 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 96 11.1. Normative References . . . . . . . . . . . . . . . . . . . 12 97 11.2. Informative References . . . . . . . . . . . . . . . . . . 12 98 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13 100 1. Introduction 102 In certain networks, such as, but not limited to, financial 103 information networks (e.g. stock market data providers), network 104 performance information (e.g. latency) is becoming as critical to 105 data path selection as other metrics. 107 In these networks, extremely large amounts of money rest on the 108 ability to access market data in "real time" and to predictably make 109 trades faster than the competition. Because of this, using metrics 110 such as hop count or cost as routing metrics is becoming only 111 tangentially important. Rather, it would be beneficial to be able to 112 make path selection decisions based on performance data (such as 113 latency) in a cost-effective and scalable way. 115 This document describes extensions to IS-IS Extended Reachability TLV 116 defined in [RFC5305] (hereafter called "IS-IS TE Express Path"), that 117 can be used to distribute network performance information (such as 118 link delay, delay variation, packet loss, residual bandwidth, and 119 available bandwidth). 121 The data distributed by IS-IS TE Express Path is meant to be used as 122 part of the operation of the routing protocol (e.g. by replacing cost 123 with latency or considering bandwidth as well as cost), by enhancing 124 CSPF, or for other uses such as supplementing the data used by an 125 Alto server [I-D.ietf-alto-protocol]. With respect to CSPF, the data 126 distributed by IS- IS TE Express Path can be used to setup, fail 127 over, and fail back data paths using protocols such as RSVP-TE 128 [RFC3209]. 130 Note that the mechanisms described in this document only disseminate 131 performance information. The methods for initially gathering that 132 performance information, such as [RFC6375], or acting on it once it 133 is distributed are outside the scope of this document. 135 2. Express Path Extensions to IS-IS TE 137 This document proposes new IS-IS TE sub-TLVs that can be announced in 138 ISIS Extended Reachability TLV (TLV-22) to distribute network 139 performance information. The extensions in this document build on 140 the ones provided in IS-IS TE [RFC5305] and GMPLS [RFC4203]. 142 IS-IS Extended Reachability TLV 22 (defined in [RFC5305]), Inter-AS 143 reachability information TLV 141 (defined in [RFC5316]) and MT-ISN 144 TLV 222 (defined in [RFC5120]) have nested sub-TLVs which permit the 145 TLVs to be readily extended. This document proposes several 146 additional sub-TLVs: 148 Type Value 150 TBD1 Unidirectional Link Delay 152 TBD2 Unidirectional Delay Variation 154 TBD3 Unidirectional Packet Loss 156 TBD4 Unidirectional Residual Bandwidth Sub TLV 158 TBD5 Unidirectional Available Bandwidth Sub TLV 160 As can be seen in the list above, the sub-TLVs described in this 161 document carry different types of network performance information. 162 Many (but not all) of the sub-TLVs include a bit called the Anomalous 163 (or "A") bit. When the A bit is clear (or when the sub-TLV does not 164 include an A bit), the sub-TLV describes steady state link 165 performance. This information could conceivably be used to construct 166 a steady state performance topology for initial tunnel path 167 computation, or to verify alternative failover paths. 169 When network performance violates configurable link-local thresholds 170 a sub-TLV with the A bit set is advertised. These sub-TLVs could be 171 used by the receiving node to determine whether to fail traffic to a 172 backup path, or whether to calculate an entirely new path. From an 173 MPLS perspective, the intent of the A bit is to permit LSP ingress 174 nodes to: 176 A) Determine whether the link referenced in the sub-TLV affects any 177 of the LSPs for which it is ingress. If there are, then: 179 B) Determine whether those LSPs still meet end-to-end performance 180 objectives. If not, then: 182 C) The node could then conceivably move affected traffic to a pre- 183 established protection LSP or establish a new LSP and place the 184 traffic in it. 186 If link performance then improves beyond a configurable minimum value 187 (reuse threshold), that sub-TLV can be re-advertised with the 188 Anomalous bit cleared. In this case, a receiving node can 189 conceivably do whatever re-optimization (or failback) it wishes to do 190 (including nothing). 192 Note that when a sub-TLV does not include the A bit, that sub-TLV 193 cannot be used for failover purposes. The A bit was intentionally 194 omitted from some sub-TLVs to help mitigate oscillations. See 195 Section 4 for more information. 197 Consistent with existing IS-IS TE specifications [RFC5305], the 198 bandwidth advertisements defined in this draft MUST be encoded as 199 IEEE floating point values. The delay and delay variation 200 advertisements defined in this draft MUST be encoded as integer 201 values. Delay values MUST be quantified in units of microseconds, 202 packet loss MUST be quantified as a percentage of packets sent, and 203 bandwidth MUST be sent as bytes per second. All values (except 204 residual bandwidth) MUST be calculated as rolling averages where the 205 averaging period MUST be a configurable period of time. See 206 Section 4 for more information. 208 3. Sub TLV Details 210 3.1. Unidirectional Link Delay Sub-TLV 212 This sub-TLV advertises the average link delay between two directly 213 connected IS-IS neighbors. The delay advertised by this sub-TLV MUST 214 be the delay from the local neighbor to the remote one (i.e. the 215 forward path latency). The format of this sub-TLV is shown in the 216 following diagram: 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 |A| RESERVED | Delay | 222 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 223 | Delay | 224 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 226 This sub-TLV has a type of TBD1. 227 The length is 4. 229 Where: 231 "A" represents the Anomalous (A) bit. The A bit is set when the 232 measured value of this parameter exceeds its configured maximum 233 threshold. The A bit is cleared when the measured value falls below 234 its configured reuse threshold. If the A bit is clear, the sub-TLV 235 represents steady state link performance. 237 The "Reserved" field is reserved for future use. It MUST be set to 0 238 when sent and MUST be ignored when received. 240 "Delay Value" is a 24-bit field carries the average link delay over a 241 configurable interval in micro-seconds, encoded as an integer value. 242 When set to 0, it has not been measured. When set to the maximum 243 value 16,777,215 (16.777215 sec), then the delay is at least that 244 value and may be larger. 246 3.2. Unidirectional Delay Variation Sub-TLV 248 This sub-TLV advertises the average link delay variation between two 249 directly connected IS-IS neighbors. The delay variation advertised 250 by this sub-TLV MUST be the delay from the local neighbor to the 251 remote one (i.e. the forward path latency). The format of this sub- 252 TLV is shown in the following diagram: 254 0 1 2 3 255 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 1 256 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 257 | Type | Length |A| RESERVED |Delay Variation| 258 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 259 | Delay Variation | 260 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 262 This sub-TLV has a type of TBD2. 263 The length is 4. 265 Where: 267 "A" represents the Anomalous (A) bit. The A bit is set when the 268 measured value of this parameter exceeds its configured maximum 269 threshold. The A bit is cleared when the measured value falls below 270 its configured reuse threshold. If the A bit is clear, the sub-TLV 271 represents steady state link performance. 273 The "Reserved" field is reserved for future use. It MUST be set to 0 274 when sent and MUST be ignored when received. 276 "Delay Variation" is a 24-bit field carries the average link delay 277 variation over a configurable interval in micro-seconds, encoded as 278 an integer value. When set to 0, it has not been measured. When set 279 to the maximum value 16,777,215 (16.777215 sec), then the delay is at 280 least that value and may be larger. 282 3.3. Unidirectional Link Loss Sub-TLV 284 This sub-TLV advertises the loss (as a packet percentage) between two 285 directly connected IS-IS neighbors. The link loss advertised by this 286 sub-TLV MUST be the packet loss from the local neighbor to the remote 287 one (i.e. the forward path loss). The format of this sub-TLV is 288 shown in the following diagram: 290 0 1 2 3 291 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 1 292 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 293 | Type | Length |A| RESERVED | Link Loss | 294 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 295 | Link Loss | 296 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 298 This sub-TLV has a type of TBD3. 299 The length is 4. 301 Where: 303 The "A" bit represents the Anomalous (A) bit. The A bit is set when 304 the measured value of this parameter exceeds its configured maximum 305 threshold. The A bit is cleared when the measured value falls below 306 its configured reuse threshold. If the A bit is clear, the sub-TLV 307 represents steady state link performance. 309 "Reserved" field is reserved for future use. It MUST be set to 0 310 when sent and MUST be ignored when received. 312 "Link Loss" is a 24-bit field carries link packet loss as a 313 percentage of the total traffic sent over a configurable interval. 314 The basic unit is 0.000003%, where (2^24 - 2) is 50.331642%. This 315 value is the highest packet loss percentage that can be expressed 316 (the assumption being that precision is more important on high speed 317 links than the ability to advertise loss rates greater than this, and 318 that high speed links with over 50% loss are unusable). Therefore, 319 measured values that are larger than the field maximum SHOULD be 320 encoded as the maximum value. When set to a value of all 1s (2^24 - 321 1), the link packet loss has not been measured. 323 3.4. Unidirectional Residual Bandwidth Sub-TLV 325 This TLV advertises the residual bandwidth between two directly 326 connected IS-IS neighbors. The residual bandwidth advertised by this 327 sub-TLV MUST be the residual bandwidth from the system originating 328 the sub-TLV to its neighbor. The format of this sub-TLV is shown in 329 the following diagram: 331 0 1 2 3 332 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 1 333 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 334 | Type | Length | Residual Bandwidth | 335 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 336 | Residual Bandwidth | 337 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 339 This sub-TLV has a type of TBD4. 340 The length is 4. 342 Where: 344 "Residual Bandwidth" is the residual bandwidth in IEEE floating point 345 format in units of bytes per second. The link may be a single link, 346 forwarding adjacency [RFC4206], or bundled link. For a link or 347 forwarding adjacency, residual bandwidth is defined to be Maximum 348 Link Bandwidth [RFC5305] minus the bandwidth currently allocated to 349 RSVP-TE LSPs. For a bundled link, residual bandwidth is defined to 350 be the sum of the component link residual bandwidths. 352 Note that although it may seem possible to calculate Residual 353 Bandwidth using the existing sub-TLVs in [RFC5305], this is not a 354 consistently reliable approach and hence the Residual Bandwidth sub- 355 TLV has been added here. For example, because the Maximum Reservable 356 Bandwidth [RFC5305] can be larger than the capacity of the link, 357 using it as part of an algorithm to determine the value of the 358 Maximum Link Bandwidth [RFC5305]minus the bandwidth currently 359 allocated to RSVP-TE Label Switched Paths cannot be considered 360 reliably accurate. 362 3.5. Unidirectional Available Bandwidth Sub-TLV 364 This TLV advertises the available bandwidth between two directly 365 connected IS-IS neighbors. The available bandwidth advertised in 366 this sub-TLV MUST be the available bandwidth from the originating 367 system to its neighbor. The format of this sub-TLV is shown in the 368 following diagram: 370 0 1 2 3 371 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 1 372 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 373 | Type | Length | Available Bandwidth | 374 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 375 | Available Bandwidth | 376 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 378 This sub-TLV has a type of TBD5. 379 The length is 4. 381 Where: 383 "Available Bandwidth" is a field that carries the available bandwidth 384 on a link, forwarding adjacency, or bundled link in IEEE floating 385 point format with units of bytes per second. For a link or 386 forwarding adjacency, available bandwidth is defined to be residual 387 bandwidth (see Section 3.4) minus the measured bandwidth used for the 388 actual forwarding of non-RSVP-TE Label Switched Paths packets. For a 389 bundled link, available bandwidth is defined to be the sum of the 390 component link available bandwidths. 392 4. Announcement Thresholds and Filters 394 The values advertised in all sub-TLVs MUST be controlled using an 395 exponential filter (i.e. a rolling average) with a configurable 396 measurement interval and filter coefficient. 398 Implementations are expected to provide separately configurable 399 advertisement thresholds. All thresholds MUST be configurable on a 400 per sub-TLV basis. 402 The announcement of all sub-TLVs that do not include the A bit SHOULD 403 be controlled by variation thresholds that govern when they are sent. 405 Sub-TLVs that include the A bit are governed by several thresholds. 406 Firstly, a threshold SHOULD be implemented to govern the announcement 407 of sub-TLVs that advertise a change in performance, but not an SLA 408 violation (i.e. when the A bit is not set). Secondly, 409 implementations MUST provide configurable thresholds that govern the 410 announcement of sub-TLVs with the A bit set (for the indication of a 411 performance violation). Thirdly, implementations SHOULD provide 412 reuse thresholds. These thresholds govern sub-TLV re-announcement 413 with the A bit cleared to permit fail back. 415 5. Announcement Suppression 417 When link performance average values change, but fall under the 418 threshold that would cause the announcement of a sub-TLV with the A 419 bit set, implementations MAY suppress or throttle sub-TLV 420 announcements. All suppression features and thresholds SHOULD be 421 configurable. 423 6. Network Stability and Announcement Periodicity 425 To mitigate concerns about stability, all values (except residual 426 bandwidth) MUST be calculated as rolling averages where the averaging 427 period MUST be a configurable period of time, rather than 428 instantaneous measurements. 430 Announcements MUST also be able to be throttled using configurable 431 inter-update throttle timers. The minimum announcement periodicity 432 is 1 announcement per second. 434 7. Compatibility 436 As per [RFC5305], unrecognized Sub-TLVs should be silently ignored 438 8. Security Considerations 440 This document does not introduce security issues beyond those 441 discussed in [RFC3630] and [RFC5329]. 443 9. IANA Considerations 445 IANA maintains the registry for the sub-TLVs. IS-IS TE Express Path 446 will require one new type code per sub-TLV defined in this document. 448 10. Acknowledgements 450 The authors would like to recognize Ayman Soliman and Les Ginsberg 451 for their contributions. 453 11. References 454 11.1. Normative References 456 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 457 Requirement Levels", BCP 14, RFC 2119, March 1997. 459 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., 460 and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP 461 Tunnels", RFC 3209, December 2001. 463 [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering 464 (TE) Extensions to OSPF Version 2", RFC 3630, 465 September 2003. 467 [RFC4203] Kompella, K. and Y. Rekhter, "OSPF Extensions in Support 468 of Generalized Multi-Protocol Label Switching (GMPLS)", 469 RFC 4203, October 2005. 471 [RFC4206] Kompella, K. and Y. Rekhter, "Label Switched Paths (LSP) 472 Hierarchy with Generalized Multi-Protocol Label Switching 473 (GMPLS) Traffic Engineering (TE)", RFC 4206, October 2005. 475 [RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi 476 Topology (MT) Routing in Intermediate System to 477 Intermediate Systems (IS-ISs)", RFC 5120, February 2008. 479 [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic 480 Engineering", RFC 5305, October 2008. 482 [RFC5316] Chen, M., Zhang, R., and X. Duan, "ISIS Extensions in 483 Support of Inter-Autonomous System (AS) MPLS and GMPLS 484 Traffic Engineering", RFC 5316, December 2008. 486 [RFC5329] Ishiguro, K., Manral, V., Davey, A., and A. Lindem, 487 "Traffic Engineering Extensions to OSPF Version 3", 488 RFC 5329, September 2008. 490 [RFC6375] Frost, D. and S. Bryant, "A Packet Loss and Delay 491 Measurement Profile for MPLS-Based Transport Networks", 492 RFC 6375, September 2011. 494 11.2. Informative References 496 [I-D.ietf-alto-protocol] 497 Penno, R., Alimi, R., and Y. Yang, "ALTO Protocol", 498 draft-ietf-alto-protocol-10 (work in progress), 499 October 2011. 501 Authors' Addresses 503 Stefano Previdi (editor) 504 Cisco Systems, Inc. 505 Via Del Serafico 200 506 Rome 00191 507 IT 509 Email: sprevidi@cisco.com 511 Spencer Giacalone 512 Thomson Reuters 513 195 Broadway 514 New York, NY 10007 515 USA 517 Email: Spencer.giacalone@thomsonreuters.com 519 Dave Ward 520 Cisco Systems, Inc. 521 3700 Cisco Way 522 SAN JOSE, CA 95134 523 US 525 Email: wardd@cisco.com 527 John Drake 528 Juniper Networks 529 1194 N. Mathilda Ave. 530 Sunnyvale, CA 94089 531 USA 533 Email: jdrake@juniper.net 535 Alia Atlas 536 Juniper Networks 537 1194 N. Mathilda Ave. 538 Sunnyvale, CA 94089 539 USA 541 Email: akatlas@juniper.net 542 Clarence Filsfils 543 Cisco Systems, Inc. 544 Brussels 545 Belgium 547 Email: cfilsfil@cisco.com