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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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-23) exists of draft-ietf-ospf-ospfv3-lsa-extend-10 Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 3 comments (--).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: March 2, 2017 Cisco Systems 7 August 29, 2016 9 OSPF Two-part Metric 10 draft-ietf-ospf-two-part-metric-09.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. 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 March 2, 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 Table of Contents 54 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 55 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 56 2. Proposed Enhancement . . . . . . . . . . . . . . . . . . . . 3 57 3. Speficications . . . . . . . . . . . . . . . . . . . . . . . 4 58 3.1. Router Interface Parameters . . . . . . . . . . . . . . . 4 59 3.2. Advertising Network-to-Router Metric in OSPFv2 . . . . . 4 60 3.3. Advertising Network-to-Router TE Metric . . . . . . . . . 5 61 3.4. Advertising Network-to-Router Metric in OSPFv3 . . . . . 5 62 3.5. OSPF Stub Router Behavior . . . . . . . . . . . . . . . . 5 63 3.6. SPF Calculation . . . . . . . . . . . . . . . . . . . . . 5 64 3.7. Backward Compatibility . . . . . . . . . . . . . . . . . 6 65 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 66 5. Security Considerations . . . . . . . . . . . . . . . . . . . 6 67 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 68 6.1. Normative References . . . . . . . . . . . . . . . . . . 6 69 6.2. Informative References . . . . . . . . . . . . . . . . . 7 70 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 8 71 Appendix B. Contributors' Addreses . . . . . . . . . . . . . . . 9 72 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 74 1. Introduction 76 With Open Shortest Path First (OSPF, [RFC2328], [RFC5340]) protocol, 77 for a broadcast network, a Network-LSA is advertised to list all 78 routers on the network, and each router on the network includes a 79 link in its Router-LSA to describe its connection to the network. 80 The link in the Router-LSA includes a metric but the listed routers 81 in the Network LSA do not include a metric. This is based on the 82 assumption that from a particular router, all others on the same 83 network can be reached with the same metric. 85 With some broadcast networks, different routers can be reached with 86 different metrics. [RFC6845] extends the OSPF protocol with a hybrid 87 interface type for that kind of broadcast network, where no Network 88 LSA is advertised and Router-LSAs simply include p2p links to all 89 routers on the same network with individual metrics. Broadcast 90 capability is still utilized to optimize database synchronization and 91 adjacency maintenance. 93 That works well for broadcast networks where the metric between 94 different pair of routers are really independent. For example, VPLS 95 networks. 97 With certain types of broadcast networks, further optimization can be 98 made to reduce the size of the Router-LSAs and number of updates. 100 Consider a satellite radio network with fixed and mobile ground 101 terminals. All communication goes through the satellite. When the 102 mobile terminals move about, their communication capability may 103 change. When OSPF runs over the radio network (routers being or in 104 tandem with the terminals), [RFC6845] hybrid interface can be used, 105 but with the following drawbacks. 107 Consider that one terminal/router moves into an area where its 108 communication capability degrades significantly. Through the radio 109 control protocol, all other routers determine that the metric to this 110 particular router changed and they all need to update their Router- 111 LSAs accordingly. The router in question also determines that its 112 metric to reach all others also changed and it also needs to update 113 its Router-LSA. Consider that there could be many terminals and many 114 of them can be moving fast and frequently, the number/frequency of 115 updates of those large Router-LSAs could inhibit network scaling. 117 1.1. Requirements Language 119 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 120 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 121 document are to be interpreted as described in [RFC2119]. 123 2. Proposed Enhancement 125 Notice that in the above scenario, when one terminal's communication 126 capability changes, its metric to all other terminals and the metric 127 from all other terminals to it will all change in a similar fashion. 128 Given this, the above problem can be easily addressed by breaking the 129 metric into two parts: the metric to the satellite and the metric 130 from the satellite. The metric from terminal R1 to R2 would be the 131 sum of the metric from R1 to the satellite and the metric from the 132 satellite to R2. 134 Now instead of using the [RFC6845] hybrid interface type, the network 135 is just treated as a regular broadcast network. A router on the 136 network no longer lists individual metrics to each neighbor in its 137 Router-LSA. Instead, each router advertises the metric from the 138 network to itself in addition to the normal metric for the network. 139 With the normal Router-to-Network and additional Network-to-Router 140 metrics advertised for each router, individual router-to-router 141 metric can be calculated. 143 With the proposed enhancement, the size of Router-LSA will be 144 significantly reduced. In addition, when a router's communication 145 capability changes, only that router needs to update its Router-LSA. 147 Note that while the example uses the satellite as the relay point at 148 the radio level (layer-2), at layer-3, the satellite does not 149 participate in packet forwarding. In fact, the satellite does not 150 need to be running any layer-3 protocol. Therefore for generality, 151 the metric is abstracted as to/from the "network" rather that 152 specifically to/from the "satellite". 154 3. Speficications 156 The following protocol specifications are added to or modified from 157 the base OSPF protocol. If an area contains one or more two-part 158 metric networks, then all routers in the area MUST support the 159 extensions specified herein. This is ensured by procedures described 160 in Section 3.7. 162 3.1. Router Interface Parameters 164 The "Router interface parameters" have the following additions: 166 o Two-part metric: TRUE if the interface connects to a multi-access 167 network that uses two-part metric. All routers connected to the 168 same network SHOULD have the same configuration for their 169 corresponding interfaces. 171 o Interface input cost: Link state metric from the two-part-metric 172 network to this router. Defaulted to "Interface output cost" but 173 not valid for normal networks using a single metric. May be 174 configured or dynamically adjusted to a value different from the 175 "Interface output cost". 177 3.2. Advertising Network-to-Router Metric in OSPFv2 179 For OSPFv2, the Network-to-Router metric is encoded in an OSPF 180 Extended Link TLV Sub-TLV [RFC7684], defined in this document as the 181 Network-to-Router Metric Sub-TLV. The type of the Sub-TLV is TBD2. 182 The length of the Sub-TLV is 4 (for the value part only). The value 183 part of the Sub-TLV is defined as follows: 185 0 1 2 3 186 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 1 187 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 188 | MT | 0 | MT metric | 189 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 191 Multiple such Sub-TLVs can exist in a single OSPF Extended Link TLV, 192 one for each topology [RFC4915]. The OSPF Extended Link TLV 193 identifies the transit link to the network, and is part of an OSPFv2 194 Extended-Link Opaque LSA. The Sub-TLV MUST ONLY appear in Extended- 195 Link TLVs for Link Type 2 (link to transit network), and MUST be 196 ignored if received for other link types. 198 3.3. Advertising Network-to-Router TE Metric 200 A Traffic Engineering Network-to-Router Metric Sub-TLV is defined, 201 similar to the Traffic Engineering Metric Sub-TLV defined in 202 Section 2.5.5 of [RFC3630]. The only difference is the TLV type, 203 which is TBD3. The Sub-TLV MUST only appear in type 2 Link TLVs 204 (Multi-access) of Traffic Engineer LSAs (OSPF2) or Intra-Area-TE-LSAs 205 (OSPFv3) [RFC5329], and MUST appear at most once in one such Link 206 TLV. 208 3.4. Advertising Network-to-Router Metric in OSPFv3 210 Network-to-Router metric advertisement in OSPFv3 Extended-Router-LSA 211 [I-D.ietf-ospf-ospfv3-lsa-extend] will be described in a separate 212 document. 214 3.5. OSPF Stub Router Behavior 216 When an OSPF router with interfaces including two-part metric is 217 advertising itself as a stub router [RFC6987], only the Router-to- 218 Network metric in the stub router's OSPF Router-LSA links is set to 219 the MaxLinkMetric. This is fully backward compatible and will result 220 in the same behavior as [RFC6987]. 222 3.6. SPF Calculation 224 The first stage of the shortest-path tree calculation is described in 225 section 16.1 of [RFC2328]. With two-part metric, when a vertex V 226 corresponding to a Network-LSA has just been added to the Shortest 227 Path Tree (SPT) and an adjacent vertex W (joined by a link in V's 228 corresponding Network-LSA) is being added to the candidate list, the 229 cost from V to W (W's network-to-router cost) is determined as 230 follows: 232 o For OSPFv2, if vertex W has a corresponding Extended-Link Opaque 233 LSA with an Extended Link TLV for the link from W to V, and the 234 Extended Link TLV has a Network-to-Router Metric Sub-TLV for the 235 corresponding topology, then the cost from V to W is the metric in 236 the Sub-TLV. Otherwise, the cost is 0. 238 o OSPFv3 [RFC5340] SPF changes will be described in a separate 239 document. 241 3.7. Backward Compatibility 243 Due to the change of procedures in the SPF calculation, all routers 244 in an area that includes one or more two-part metric networks must 245 support the changes specified in this document. To ensure that, if 246 an area is provisioned to support two-part metric networks, all 247 routers supporting this capability must advertise a Router 248 Information (RI) LSA with a Router Functional Capabilities TLV 249 [RFC7770] that includes the following Router Functional Capability 250 Bit: 252 Bit Capabilities 254 TBD1 OSPF Two-part Metric (TPM) 256 Upon detecting the presence of a reachable Router-LSA without a 257 companion RI LSA that has the bit set, all routers MUST recalculate 258 routes without considering any network-to-router costs. 260 4. IANA Considerations 262 This document requests the following IANA assignments: 264 o A new bit (TBD1) in Registry for OSPF Router Informational 265 Capability Bits, to indicate the capability of supporting two-part 266 metric. 268 o A new Sub-TLV type (TBD2) in OSPF Extended Link TLV Sub-TLV 269 registry, for the Network-to-Router Metric Sub-TLV. 271 o A new Sub-TLV type (TBD3) in Types for sub-TLVs of TE Link TLV 272 (Value 2) registry, for the Network-to-Router TE Metric Sub-TLV. 274 5. Security Considerations 276 This document does not introduce new security risks. Existing 277 security considerations in OSPFv2 and OSPFv3 apply. 279 6. References 281 6.1. Normative References 283 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 284 Requirement Levels", BCP 14, RFC 2119, 285 DOI 10.17487/RFC2119, March 1997, 286 . 288 [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, 289 DOI 10.17487/RFC2328, April 1998, 290 . 292 [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering 293 (TE) Extensions to OSPF Version 2", RFC 3630, 294 DOI 10.17487/RFC3630, September 2003, 295 . 297 [RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P. 298 Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF", 299 RFC 4915, DOI 10.17487/RFC4915, June 2007, 300 . 302 [RFC5329] Ishiguro, K., Manral, V., Davey, A., and A. Lindem, Ed., 303 "Traffic Engineering Extensions to OSPF Version 3", 304 RFC 5329, DOI 10.17487/RFC5329, September 2008, 305 . 307 [RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W., 308 Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute 309 Advertisement", RFC 7684, DOI 10.17487/RFC7684, November 310 2015, . 312 [RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and 313 S. Shaffer, "Extensions to OSPF for Advertising Optional 314 Router Capabilities", RFC 7770, DOI 10.17487/RFC7770, 315 February 2016, . 317 6.2. Informative References 319 [I-D.ietf-ospf-ospfv3-lsa-extend] 320 Lindem, A., Mirtorabi, S., Roy, A., and F. Baker, "OSPFv3 321 LSA Extendibility", draft-ietf-ospf-ospfv3-lsa-extend-10 322 (work in progress), May 2016. 324 [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 325 for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, 326 . 328 [RFC6845] Sheth, N., Wang, L., and J. Zhang, "OSPF Hybrid Broadcast 329 and Point-to-Multipoint Interface Type", RFC 6845, 330 DOI 10.17487/RFC6845, January 2013, 331 . 333 [RFC6987] Retana, A., Nguyen, L., Zinin, A., White, R., and D. 334 McPherson, "OSPF Stub Router Advertisement", RFC 6987, 335 DOI 10.17487/RFC6987, September 2013, 336 . 338 Appendix A. Acknowledgements 340 The authors would like to thank Abhay Roy, Hannes Gredler, Peter 341 Psenak and Eric Wu for their comments and suggestions. 343 The RFC text was produced using Marshall Rose's xml2rfc tool. 345 Appendix B. Contributors' Addreses 347 David Dubois 348 General Dynamics C4S 349 400 John Quincy Adams Road 350 Taunton, MA 02780 352 EMail: dave.dubois@gd-ms.com 354 Vibhor Julka 355 Individual 357 EMail: vjulka1@yahoo.com 359 Tom McMillan 360 L3 Communications, Linkabit 361 9890 Towne Centre Drive 362 San Diego, CA 92121 364 EMail: tom.mcmillan@l-3com.com 366 Authors' Addresses 368 Zhaohui Zhang 369 Juniper Networks, Inc. 370 10 Technology Park Drive 371 Westford, MA 01886 373 Email: zzhang@juniper.net 375 Lili Wang 376 Juniper Networks, Inc. 377 10 Technology Park Drive 378 Westford, MA 01886 380 Email: liliw@juniper.net 382 Acee Lindem 383 Cisco Systems 384 301 Midenhall Way 385 Cary, NC 27513 387 Email: acee@cisco.com