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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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-23) exists of draft-ietf-ospf-ospfv3-lsa-extend-10 Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group Z. Zhang 3 Internet-Draft L. Wang 4 Updates: 2328, 5340 (if approved) Juniper Networks, Inc. 5 Intended status: Standards Track A. Lindem 6 Expires: February 9, 2017 Cisco Systems 7 August 8, 2016 9 OSPF Two-part Metric 10 draft-ietf-ospf-two-part-metric-07.txt 12 Abstract 14 This document specifies an optional extension to the OSPF protocol, 15 to represent the metric on a multi-access network as two parts: the 16 metric from a router to the network, and the metric from the network 17 to the router. The router to router metric would be the sum of the 18 two. This document updates RFC 2328 and RFC 5340. 20 Status of This Memo 22 This Internet-Draft is submitted in full conformance with the 23 provisions of BCP 78 and BCP 79. 25 Internet-Drafts are working documents of the Internet Engineering 26 Task Force (IETF). Note that other groups may also distribute 27 working documents as Internet-Drafts. The list of current Internet- 28 Drafts is at http://datatracker.ietf.org/drafts/current/. 30 Internet-Drafts are draft documents valid for a maximum of six months 31 and may be updated, replaced, or obsoleted by other documents at any 32 time. It is inappropriate to use Internet-Drafts as reference 33 material or to cite them other than as "work in progress." 35 This Internet-Draft will expire on February 9, 2017. 37 Copyright Notice 39 Copyright (c) 2016 IETF Trust and the persons identified as the 40 document authors. All rights reserved. 42 This document is subject to BCP 78 and the IETF Trust's Legal 43 Provisions Relating to IETF Documents 44 (http://trustee.ietf.org/license-info) in effect on the date of 45 publication of this document. Please review these documents 46 carefully, as they describe your rights and restrictions with respect 47 to this document. Code Components extracted from this document must 48 include Simplified BSD License text as described in Section 4.e of 49 the Trust Legal Provisions and are provided without warranty as 50 described in the Simplified BSD License. 52 This document may contain material from IETF Documents or IETF 53 Contributions published or made publicly available before November 54 10, 2008. The person(s) controlling the copyright in some of this 55 material may not have granted the IETF Trust the right to allow 56 modifications of such material outside the IETF Standards Process. 57 Without obtaining an adequate license from the person(s) controlling 58 the copyright in such materials, this document may not be modified 59 outside the IETF Standards Process, and derivative works of it may 60 not be created outside the IETF Standards Process, except to format 61 it for publication as an RFC or to translate it into languages other 62 than English. 64 Table of Contents 66 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 67 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 68 2. Proposed Enhancement . . . . . . . . . . . . . . . . . . . . 3 69 3. Speficications . . . . . . . . . . . . . . . . . . . . . . . 4 70 3.1. Router Interface Parameters . . . . . . . . . . . . . . . 4 71 3.2. Advertising Network-to-Router Metric in OSPFv2 . . . . . 4 72 3.3. Advertising Network-to-Router Metric in OSPFv3 . . . . . 5 73 3.4. Advertising Network-to-Router TE Metric . . . . . . . . . 5 74 3.5. OSPF Stub Router Behavior . . . . . . . . . . . . . . . . 5 75 3.6. SPF Calculation . . . . . . . . . . . . . . . . . . . . . 6 76 3.7. Backward Compatibility . . . . . . . . . . . . . . . . . 6 77 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 78 5. Security Considerations . . . . . . . . . . . . . . . . . . . 7 79 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 80 6.1. Normative References . . . . . . . . . . . . . . . . . . 7 81 6.2. Informative References . . . . . . . . . . . . . . . . . 8 82 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 8 83 Appendix B. Contributors' Addreses . . . . . . . . . . . . . . . 9 84 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 86 1. Introduction 88 With Open Shortest Path First (OSPF, [RFC2328], [RFC5340]) protocol, 89 for a broadcast network, a Network-LSA is advertised to list all 90 routers on the network, and each router on the network includes a 91 link in its Router-LSA to describe its connection to the network. 92 The link in the Router-LSA includes a metric but the listed routers 93 in the Network LSA do not include a metric. This is based on the 94 assumption that from a particular router, all others on the same 95 network can be reached with the same metric. 97 With some broadcast networks, different routers can be reached with 98 different metrics. [RFC6845] extends the OSPF protocol with a hybrid 99 interface type for that kind of broadcast network, where no Network 100 LSA is advertised and Router-LSAs simply include p2p links to all 101 routers on the same network with individual metrics. Broadcast 102 capability is still utilized to optimize database synchronization and 103 adjacency maintenance. 105 That works well for broadcast networks where the metric between 106 different pair of routers are really independent. For example, VPLS 107 networks. 109 With certain types of broadcast networks, further optimization can be 110 made to reduce the size of the Router-LSAs and number of updates. 112 Consider a satellite radio network with fixed and mobile ground 113 terminals. All communication goes through the satellite. When the 114 mobile terminals move about, their communication capability may 115 change. When OSPF runs over the radio network (routers being or in 116 tandem with the terminals), [RFC6845] hybrid interface can be used, 117 but with the following drawbacks. 119 Consider that one terminal/router moves into an area where its 120 communication capability degrades significantly. Through the radio 121 control protocol, all other routers determine that the metric to this 122 particular router changed and they all need to update their Router- 123 LSAs accordingly. The router in question also determines that its 124 metric to reach all others also changed and it also needs to update 125 its Router-LSA. Consider that there could be many terminals and many 126 of them can be moving fast and frequently, the number/frequency of 127 updates of those large Router-LSAs could inhibit network scaling. 129 1.1. Requirements Language 131 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 132 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 133 document are to be interpreted as described in [RFC2119]. 135 2. Proposed Enhancement 137 Notice that in the above scenario, when one terminal's communication 138 capability changes, its metric to all other terminals and the metric 139 from all other terminals to it will all change in a similar fashion. 140 Given this, the above problem can be easily addressed by breaking the 141 metric into two parts: the metric to the satellite and the metric 142 from the satellite. The metric from terminal R1 to R2 would be the 143 sum of the metric from R1 to the satellite and the metric from the 144 satellite to R2. 146 Now instead of using the [RFC6845] hybrid interface type, the network 147 is just treated as a regular broadcast network. A router on the 148 network no longer lists individual metrics to each neighbor in its 149 Router-LSA. Instead, each router advertises the metric from the 150 network to itself in addition to the normal metric for the network. 151 With the normal Router-to-Network and additional Network-to-Router 152 metrics advertised for each router, individual router-to-router 153 metric can be calculated. 155 With the proposed enhancement, the size of Router-LSA will be 156 significantly reduced. In addition, when a router's communication 157 capability changes, only that router needs to update its Router-LSA. 159 Note that while the example uses the satellite as the relay point at 160 the radio level (layer-2), at layer-3, the satellite does not 161 participate in packet forwarding. In fact, the satellite does not 162 need to be running any layer-3 protocol. Therefore for generality, 163 the metric is abstracted as to/from the "network" rather that 164 specifically to/from the "satellite". 166 3. Speficications 168 The following protocol specifications are added to or modified from 169 the base OSPF protocol. If an area contains one or more two-part 170 metric networks, then all routers in the area MUST support the 171 extensions specified herein. This is ensured by procedures described 172 in Section 3.7. 174 3.1. Router Interface Parameters 176 The "Router interface parameters" have the following additions: 178 o Two-part metric: TRUE if the interface connects to a multi-access 179 network that uses two-part metric. All routers connected to the 180 same network SHOULD have the same configuration for their 181 corresponding interfaces. 183 o Interface input cost: Link state metric from the two-part-metric 184 network to this router. Defaulted to "Interface output cost" but 185 not valid for normal networks using a single metric. May be 186 configured or dynamically adjusted to a value different from the 187 "Interface output cost". 189 3.2. Advertising Network-to-Router Metric in OSPFv2 191 For OSPFv2, the Network-to-Router metric is encoded in an OSPF 192 Extended Link TLV Sub-TLV [RFC7684], defined in this document as the 193 Network-to-Router Metric Sub-TLV. The type of the Sub-TLV is TBD2. 195 The length of the Sub-TLV is 4 (for the value part only). The value 196 part of the Sub-TLV is defined as follows: 198 0 1 2 3 199 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 1 200 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 201 | MT | 0 | MT metric | 202 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 204 Multiple such Sub-TLVs can exist in a single OSPF Extended Link TLV, 205 one for each topology [RFC4915]. The OSPF Extended Link TLV 206 identifies the transit link to the network, and is part of an OSPFv2 207 Extended-Link Opaque LSA. The Sub-TLV MUST ONLY appear in Extended- 208 Link TLVs for Link Type 2 (link to transit network), and MUST be 209 ignored if received for other link types. 211 3.3. Advertising Network-to-Router Metric in OSPFv3 213 For OSPFv3, the same Network-to-Router Metric Sub-TLV definition is 214 used, though it is part of the Router-Link TLV of E-Router-LSA 215 [I-D.ietf-ospf-ospfv3-lsa-extend] and the type is TBD3. Currently 216 OSPFv3 Multi-Toplogy is not defined so the only valid value for the 217 MT field is 0 and only one such Sub-TLV SHOULD be included in the 218 Router-Link TLV. Received Sub-TLVs with non-zero MT field MUST be 219 ignored. 221 Similarly, the Sub-TLV MUST ONLY appear in Router-Link TLVs for Link 222 Type 2 (connection to a transit network) and MUST be ignored if 223 received for other link types. 225 3.4. Advertising Network-to-Router TE Metric 227 A Traffic Engineering Network-to-Router Metric Sub-TLV is defined, 228 similar to the Traffic Engineering Metric Sub-TLV defined in 229 Section 2.5.5 of [RFC3630]. The only difference is the TLV type, 230 which is TBD4. The Sub-TLV MUST only appear in type 2 Link TLVs 231 (Multi-access) of Traffic Engineer LSAs (OSPF2) or Intra-Area-TE-LSAs 232 (OSPFv3) [RFC5329], and MUST appear at most once in one such Link 233 TLV. 235 3.5. OSPF Stub Router Behavior 237 When an OSPF router with interfaces including two-part metric is 238 advertising itself as a stub router [RFC6987], only the Router-to- 239 Network metric in the stub router's OSPF Router-LSA links is set to 240 the MaxLinkMetric. This is fully backward compatible and will result 241 in the same behavior as [RFC6987]. 243 3.6. SPF Calculation 245 The first stage of the shortest-path tree calculation is described in 246 section 16.1 of [RFC2328] and modified for OSPFv3 as described in 247 section 4.8.1 of [RFC5340]. With two-part metric, when a vertex V 248 corresponding to a Network-LSA has just been added to the Shortest 249 Path Tree (SPT) and an adjacent vertex W (joined by a link in V's 250 corresponding Network-LSA) is being added to the candidate list, the 251 cost from V to W (W's network-to-router cost) is determined as 252 follows: 254 o For OSPFv2, if vertex W has a corresponding Extended-Link Opaque 255 LSA with an Extended Link TLV for the link from W to V, and the 256 Extended Link TLV has a Network-to-Router Metric Sub-TLV for the 257 corresponding topology, then the cost from V to W is the metric in 258 the Sub-TLV. Otherwise, the cost is 0. 260 o For OSPFv3, if vertex W has a corresponding E-Router-LSA with a 261 Router-Link TLV for the link from W to V, and the Router-Link TLV 262 has a Network-to-Router Metric Sub-TLV, then the cost from V to W 263 is the metric in the Sub-TLV. If not, the cost is 0. 265 3.7. Backward Compatibility 267 Due to the change of procedures in the SPF calculation, all routers 268 in an area that includes one or more two-part metric networks must 269 support the changes specified in this document. To ensure that, if 270 an area is provisioned to support two-part metric networks, all 271 routers supporting this capability must advertise a Router 272 Information (RI) LSA with a Router Functional Capabilities TLV 273 [RFC7770] that includes the following Router Functional Capability 274 Bit: 276 Bit Capabilities 278 TBD1 OSPF Two-part Metric (TPM) 280 Upon detecting the presence of a reachable Router-LSA without a 281 companion RI LSA that has the bit set, all routers MUST recalculate 282 routes without considering any network-to-router costs. 284 4. IANA Considerations 286 This document requests the following IANA assignments: 288 o A new bit (TBD1) in Registry for OSPF Router Informational 289 Capability Bits, to indicate the capability of supporting two-part 290 metric. 292 o A new Sub-TLV type (TBD2) in OSPF Extended Link TLV Sub-TLV 293 registry, for the Network-to-Router Metric Sub-TLV. 295 o A new Sub-TLV type (TBD3) in OSPFv3 Extended-LSA Sub-TLV registry, 296 for the Network-to-Router Metric Sub-TLV. 298 o A new Sub-TLV type (TBD4) in Types for sub-TLVs of TE Link TLV 299 (Value 2) registry, for the Network-to-Router TE Metric Sub-TLV. 301 5. Security Considerations 303 This document does not introduce new security risks. Existing 304 security considerations in OSPFv2 and OSPFv3 apply. 306 6. References 308 6.1. Normative References 310 [I-D.ietf-ospf-ospfv3-lsa-extend] 311 Lindem, A., Mirtorabi, S., Roy, A., and F. Baker, "OSPFv3 312 LSA Extendibility", draft-ietf-ospf-ospfv3-lsa-extend-10 313 (work in progress), May 2016. 315 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 316 Requirement Levels", BCP 14, RFC 2119, 317 DOI 10.17487/RFC2119, March 1997, 318 . 320 [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, 321 DOI 10.17487/RFC2328, April 1998, 322 . 324 [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering 325 (TE) Extensions to OSPF Version 2", RFC 3630, 326 DOI 10.17487/RFC3630, September 2003, 327 . 329 [RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P. 330 Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF", 331 RFC 4915, DOI 10.17487/RFC4915, June 2007, 332 . 334 [RFC5329] Ishiguro, K., Manral, V., Davey, A., and A. Lindem, Ed., 335 "Traffic Engineering Extensions to OSPF Version 3", 336 RFC 5329, DOI 10.17487/RFC5329, September 2008, 337 . 339 [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 340 for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, 341 . 343 [RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W., 344 Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute 345 Advertisement", RFC 7684, DOI 10.17487/RFC7684, November 346 2015, . 348 [RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and 349 S. Shaffer, "Extensions to OSPF for Advertising Optional 350 Router Capabilities", RFC 7770, DOI 10.17487/RFC7770, 351 February 2016, . 353 6.2. Informative References 355 [RFC6845] Sheth, N., Wang, L., and J. Zhang, "OSPF Hybrid Broadcast 356 and Point-to-Multipoint Interface Type", RFC 6845, 357 DOI 10.17487/RFC6845, January 2013, 358 . 360 [RFC6987] Retana, A., Nguyen, L., Zinin, A., White, R., and D. 361 McPherson, "OSPF Stub Router Advertisement", RFC 6987, 362 DOI 10.17487/RFC6987, September 2013, 363 . 365 Appendix A. Acknowledgements 367 The authors would like to thank Abhay Roy, Hannes Gredler, Peter 368 Psenak and Eric Wu for their comments and suggestions. 370 The RFC text was produced using Marshall Rose's xml2rfc tool. 372 Appendix B. Contributors' Addreses 374 David Dubois 375 General Dynamics C4S 376 400 John Quincy Adams Road 377 Taunton, MA 02780 379 EMail: dave.dubois@gd-ms.com 381 Vibhor Julka 382 Individual 384 EMail: vjulka1@yahoo.com 386 Tom McMillan 387 L3 Communications, Linkabit 388 9890 Towne Centre Drive 389 San Diego, CA 92121 391 EMail: tom.mcmillan@l-3com.com 393 Authors' Addresses 395 Zhaohui Zhang 396 Juniper Networks, Inc. 397 10 Technology Park Drive 398 Westford, MA 01886 400 Email: zzhang@juniper.net 402 Lili Wang 403 Juniper Networks, Inc. 404 10 Technology Park Drive 405 Westford, MA 01886 407 Email: liliw@juniper.net 409 Acee Lindem 410 Cisco Systems 411 301 Midenhall Way 412 Cary, NC 27513 414 Email: acee@cisco.com