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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) == Missing Reference: 'TPM' is mentioned on line 264, but not defined == Unused Reference: 'I-D.acee-ospf-rfc4970bis' is defined on line 299, but no explicit reference was found in the text == Unused Reference: 'I-D.ietf-ospf-ospfv3-lsa-extend' is defined on line 305, but no explicit reference was found in the text == Outdated reference: draft-ietf-ospf-ospfv3-lsa-extend has been published as RFC 8362 Summary: 0 errors (**), 0 flaws (~~), 5 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Open Shortest Path First 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: November 5, 2016 Cisco Systems 7 D. Dubois 8 General Dynamics C4S 9 V. Julka 10 T. McMillan 11 L3 Communications, Linkabit 12 May 4, 2016 14 OSPF Two-part Metric 15 draft-ietf-ospf-two-part-metric-04.txt 17 Abstract 19 This document specifies an optional extension to the OSPF protocol, 20 to represent the metric on a multi-access network as two parts: the 21 metric from a router to the network, and the metric from the network 22 to the router. The router to router metric would be the sum of the 23 two. This document updates RFC 2328 and RFC 5340. 25 Requirements Language 27 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 28 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 29 document are to be interpreted as described in [RFC2119]. 31 Status of This Memo 33 This Internet-Draft is submitted in full conformance with the 34 provisions of BCP 78 and BCP 79. 36 Internet-Drafts are working documents of the Internet Engineering 37 Task Force (IETF). Note that other groups may also distribute 38 working documents as Internet-Drafts. The list of current Internet- 39 Drafts is at http://datatracker.ietf.org/drafts/current/. 41 Internet-Drafts are draft documents valid for a maximum of six months 42 and may be updated, replaced, or obsoleted by other documents at any 43 time. It is inappropriate to use Internet-Drafts as reference 44 material or to cite them other than as "work in progress." 46 This Internet-Draft will expire on November 5, 2016. 48 Copyright Notice 50 Copyright (c) 2016 IETF Trust and the persons identified as the 51 document authors. All rights reserved. 53 This document is subject to BCP 78 and the IETF Trust's Legal 54 Provisions Relating to IETF Documents 55 (http://trustee.ietf.org/license-info) in effect on the date of 56 publication of this document. Please review these documents 57 carefully, as they describe your rights and restrictions with respect 58 to this document. Code Components extracted from this document must 59 include Simplified BSD License text as described in Section 4.e of 60 the Trust Legal Provisions and are provided without warranty as 61 described in the Simplified BSD License. 63 Table of Contents 65 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 66 2. Proposed Enhancement . . . . . . . . . . . . . . . . . . . . 3 67 3. Speficications . . . . . . . . . . . . . . . . . . . . . . . 4 68 3.1. Router Interface Parameters . . . . . . . . . . . . . . . 4 69 3.2. Advertising Network-to-Router Metric in OSPFv2 . . . . . 4 70 3.3. Advertising Network-to-Router Metric in OSPFv3 . . . . . 5 71 3.4. Advertising Network-to-Router TE Metric . . . . . . . . . 5 72 3.5. OSPF Stub Router Behavior . . . . . . . . . . . . . . . . 5 73 3.6. SPF Calculation . . . . . . . . . . . . . . . . . . . . . 6 74 3.7. Backward Compatibility . . . . . . . . . . . . . . . . . 6 75 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 76 5. Security Considerations . . . . . . . . . . . . . . . . . . . 7 77 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7 78 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 79 7.1. Normative References . . . . . . . . . . . . . . . . . . 7 80 7.2. Informative References . . . . . . . . . . . . . . . . . 8 81 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 83 1. Introduction 85 With Open Shortest Path First (OSPF, [RFC2328, RFC5340]) protocol, 86 for a broadcast network, a Network-LSA is advertised to list all 87 routers on the network, and each router on the network includes a 88 link in its Router-LSA to describe its connection to the network. 89 The link in the Router-LSA includes a metric but the listed routers 90 in the Network LSA do not include a metric. This is based on the 91 assumption that from a particular router, all others on the same 92 network can be reached with the same metric. 94 With some broadcast networks, different routers can be reached with 95 different metrics. [RFC6845] extends the OSPF protocol with a hybrid 96 interface type for that kind of broadcast network, where no Network 97 LSA is advertised and Router-LSAs simply include p2p links to all 98 routers on the same network with individual metrics. Broadcast 99 capability is still utilized to optimize database synchronization and 100 adjacency maintenance. 102 That works well for broadcast networks where the metric between 103 different pair of routers are really independent. For example, VPLS 104 networks. 106 With certain types of broadcast networks, further optimization can be 107 made to reduce the size of the Router-LSAs and number of updates. 109 Consider a satellite radio network with fixed and mobile ground 110 terminals. All communication goes through the satellite. When the 111 mobile terminals move about, their communication capability may 112 change. When OSPF runs over the radio network (routers being or in 113 tandem with the terminals), [RFC6845] hybrid interface can be used, 114 but with the following drawbacks. 116 Consider that one terminal/router moves into an area where its 117 communication capability degrades significantly. Through the radio 118 control protocol, all other routers determine that the metric to this 119 particular router changed and they all need to update their Router- 120 LSAs accordingly. The router in question also determines that its 121 metric to reach all others also changed and it also needs to update 122 its Router-LSA. Consider that there could be many terminals and many 123 of them can be moving fast and frequently, the number/frequency of 124 updates of those large Router-LSAs could inhibit network scaling. 126 2. Proposed Enhancement 128 Notice that in the above scenario, when one terminal's communication 129 capability changes, its metric to all other terminals and the metric 130 from all other terminals to it will all change in a similar fashion. 131 Given this, the above problem can be easily addressed by breaking the 132 metric into two parts: the metric to the satellite and the metric 133 from the satellite. The metric from terminal R1 to R2 would be the 134 sum of the metric from R1 to the satellite and the metric from the 135 satellite to R2. 137 Now instead of using the [RFC6845] hybrid interface type, the network 138 is just treated as a regular broadcast network. A router on the 139 network no longer lists individual metrics to each neighbor in its 140 Router-LSA. Instead, each router advertises the metric from the 141 network to itself in addition to the normal metric for the network. 142 With the normal Router-to-Network and additional Network-to-Router 143 metrics advertised for each router, individual router-to-router 144 metric can be calculated. 146 With the proposed enhancement, the size of Router-LSA will be 147 significantly reduced. In addition, when a router's communication 148 capability changes, only that router needs to update its Router-LSA. 150 Note that while the example uses the satellite as the relay point at 151 the radio level (layer-2), at layer-3, the satellite does not 152 participate in packet forwarding. In fact, the satellite does not 153 need to be running any layer-3 protocol. Therefore for generality, 154 the metric is abstracted as to/from the "network" rather that 155 specifically to/from the "satellite". 157 3. Speficications 159 The following protocol specifications are added to or modified from 160 the base OSPF protocol. If an area contains one or more two-part 161 metric networks, then all routers in the area must support the 162 extensions specified herein. This is ensured by procedures described 163 in Section 3.7. 165 3.1. Router Interface Parameters 167 The "Router interface parameters" have the following additions: 169 o Two-part metric: TRUE if the interface connects to a multi-access 170 network that uses two-part metric. All routers connected to the 171 same network SHOULD have the same configuration for their 172 corresponding interfaces. 174 o Interface input cost: Link state metric from the two-part-metric 175 network to this router. Defaulted to "Interface output cost" but 176 not valid for normal networks using a single metric. May be 177 configured or dynamically adjusted to a value different from the 178 "Interface output cost". 180 3.2. Advertising Network-to-Router Metric in OSPFv2 182 For OSPFv2, the Network-to-Router metric is encoded in an OSPF 183 Extended Link TLV Sub-TLV [RFC7684], defined in this document as the 184 Network-to-Router Metric Sub-TLV. The type of the Sub-TLV is TBD. 185 The length of the Sub-TLV is 4 (for the value part only). The value 186 part of the Sub-TLV is defined as follows: 188 0 1 2 3 189 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 1 190 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 191 | MT | 0 | MT metric | 192 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 194 Multiple such Sub-TLVs can exist in a single OSPF Extended Link TLV, 195 one for each topology [RFC4915]. The OSPF Extended Link TLV 196 identifies the transit link to the network, and is part of an OSPFv2 197 Extended-Link Opaque LSA. The Sub-TLV MUST ONLY appear in Extended- 198 Link TLVs for Link Type 2 (link to transit network), and MUST be 199 ignored if received for other link types. 201 3.3. Advertising Network-to-Router Metric in OSPFv3 203 For OSPFv3, the same Network-to-Router Metric Sub-TLV definition is 204 used, though it is part of the Router-Link TLV of E-Router-LSA [I- 205 D.ietf-ospf-ospfv3-lsa-extend]. Currently OSPFv3 Multi-Toplogy is 206 not defined so the only valid value for the MT field is 0 and only 207 one such Sub-TLV SHOULD be included in the Router-Link TLV. Received 208 Sub-TLVs with non-zero MT field MUST be ignored. 210 Similarly, the Sub-TLV MUST ONLY appear in Router-Link TLVs for Link 211 Type 2 (connection to a transit network) and MUST be ignored if 212 received for other link types. 214 3.4. Advertising Network-to-Router TE Metric 216 A Traffic Engineering Network-to-Router Metric Sub-TLV is defined, 217 similar to the Traffic Engineering Metric Sub-TLV defined in 218 Section 2.5.5 of [RFC3630]. The only difference is the TLV type, 219 which is TBD. The Sub-TLV MUST only appear in type 2 Link TLVs 220 (Multi-access) of Traffic Engineer LSAs (OSPF2) or Intra-Area-TE-LSAs 221 (OSPFv3) [RFC5329], and MUST appear at most once in one such Link 222 TLV. 224 3.5. OSPF Stub Router Behavior 226 When an OSPF router with interfaces including two-part metric is 227 advertising itself as a stub router [RFC6987], only the Router-to- 228 Network metric in the stub router's OSPF Router-LSA links is set to 229 the MaxLinkMetric. This is fully backward compatible and will result 230 in the same behavior as [RFC6987]. 232 3.6. SPF Calculation 234 During the first stage of shortest-path tree calculation for an area, 235 when a vertex V corresponding to a Network-LSA is added to the 236 shortest-path tree and its adjacent vertex W (joined by a link in V's 237 corresponding Network LSA), the cost from V to W, which is W's 238 network-to-router cost, is determined as follows: 240 o For OSPFv2, if vertex W has a corresponding Extended-Link Opaque 241 LSA with an Extended Link TLV for the link from W to V, and the 242 Extended Link TLV has a Network-to-Router Metric Sub-TLV for the 243 corresponding topology, then the cost from V to W is the metric in 244 the Sub-TLV. Otherwise, the cost is 0. 246 o For OSPFv3, if vertex W has a corresponding E-Router-LSA with a 247 Router-Link TLV for the link from W to V, and the Router-Link TLV 248 has a Network-to-Router Metric Sub-TLV, then the cost from V to W 249 is the metric in the Sub-TLV. If not, the cost is 0. 251 3.7. Backward Compatibility 253 Due to the change of procedures in the SPF calculation, all routers 254 in an area that includes one or more two-part metric networks must 255 support the changes specified in this document. To ensure that, if 256 an area is provisioned to support two-part metric networks, all 257 routers supporting this capability must advertise a Router 258 Information (RI) LSA with a Router Functional Capabilities TLV [I- 259 D.acee-ospf-rfc4970bis] that includes the following Router Functional 260 Capability Bit: 262 Bit Capabilities 264 0 OSPF Two-part Metric [TPM] 266 Upon detecting the presence of a reachable Router-LSA without a 267 companion RI LSA that has the bit set, all routers MUST recalculate 268 routes w/o considering any network-to-router costs. 270 4. IANA Considerations 272 This document requests the following IANA assignments: 274 o A new bit in Registry for OSPF Router Informational Capability 275 Bits, to indicate the capability of supporting two-part metric. 277 o A new Sub-TLV type in OSPF Extended Link TLV Sub-TLV registry, for 278 the Network-to-Router Metric Sub-TLV. 280 o A new Sub-TLV type in OSPFv3 Extended-LSA Sub-TLV registry, for 281 the Network-to-Router Metric Sub-TLV. 283 o A new Sub-TLV type in Types for sub-TLVs of TE Link TLV (Value 2) 284 registry, for the Network-to-Router TE Metric Sub-TLV. 286 5. Security Considerations 288 This document does not introduce new security risks. 290 6. Acknowledgements 292 The authors would like to thank Abhay Roy, Hannes Gredler, Peter 293 Psenak and Eric Wu for their comments and suggestions. 295 7. References 297 7.1. Normative References 299 [I-D.acee-ospf-rfc4970bis] 300 Lindem, A., Shen, N., Vasseur, J., Aggarwal, R., and S. 301 Shaffer, "Extensions to OSPF for Advertising Optional 302 Router Capabilities", draft-acee-ospf-rfc4970bis-00 (work 303 in progress), July 2014. 305 [I-D.ietf-ospf-ospfv3-lsa-extend] 306 Lindem, A., Mirtorabi, S., Roy, A., and F. Baker, "OSPFv3 307 LSA Extendibility", draft-ietf-ospf-ospfv3-lsa-extend-09 308 (work in progress), November 2015. 310 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 311 Requirement Levels", BCP 14, RFC 2119, 312 DOI 10.17487/RFC2119, March 1997, 313 . 315 [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, 316 DOI 10.17487/RFC2328, April 1998, 317 . 319 [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering 320 (TE) Extensions to OSPF Version 2", RFC 3630, 321 DOI 10.17487/RFC3630, September 2003, 322 . 324 [RFC4915] Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P. 325 Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF", 326 RFC 4915, DOI 10.17487/RFC4915, June 2007, 327 . 329 [RFC5329] Ishiguro, K., Manral, V., Davey, A., and A. Lindem, Ed., 330 "Traffic Engineering Extensions to OSPF Version 3", 331 RFC 5329, DOI 10.17487/RFC5329, September 2008, 332 . 334 [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 335 for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, 336 . 338 [RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W., 339 Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute 340 Advertisement", RFC 7684, DOI 10.17487/RFC7684, November 341 2015, . 343 7.2. Informative References 345 [RFC6845] Sheth, N., Wang, L., and J. Zhang, "OSPF Hybrid Broadcast 346 and Point-to-Multipoint Interface Type", RFC 6845, 347 DOI 10.17487/RFC6845, January 2013, 348 . 350 [RFC6987] Retana, A., Nguyen, L., Zinin, A., White, R., and D. 351 McPherson, "OSPF Stub Router Advertisement", RFC 6987, 352 DOI 10.17487/RFC6987, September 2013, 353 . 355 Authors' Addresses 357 Zhaohui Zhang 358 Juniper Networks, Inc. 359 10 Technology Park Drive 360 Westford, MA 01886 362 EMail: zzhang@juniper.net 364 Lili Wang 365 Juniper Networks, Inc. 366 10 Technology Park Drive 367 Westford, MA 01886 369 EMail: liliw@juniper.net 370 Acee Lindem 371 Cisco Systems 372 301 Midenhall Way 373 Cary, NC 27513 375 EMail: acee@cisco.com 377 David Dubois 378 General Dynamics C4S 379 400 John Quincy Adams Road 380 Taunton, MA 02780 382 EMail: dave.dubois@gdc4s.com 384 Vibhor Julka 385 L3 Communications, Linkabit 386 9890 Towne Centre Drive 387 San Diego, CA 92121 389 EMail: vibhor.julka@l-3Com.com 391 Tom McMillan 392 L3 Communications, Linkabit 393 9890 Towne Centre Drive 394 San Diego, CA 92121 396 EMail: tom.mcmillan@l-3com.com