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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 (February 27, 2009) is 5536 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) No issues found here. Summary: 1 error (**), 0 flaws (~~), 1 warning (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group A. Lindem 3 Internet-Draft Redback Networks 4 Intended status: Standards Track A. Roy 5 Expires: August 31, 2009 S. Mirtorabi 6 Cisco Systems 7 February 27, 2009 9 OSPF Transport Instance Extensions 10 draft-ietf-ospf-transport-instance-00.txt 12 Status of this Memo 14 This Internet-Draft is submitted to IETF in full conformance with the 15 provisions of BCP 78 and BCP 79. 17 Internet-Drafts are working documents of the Internet Engineering 18 Task Force (IETF), its areas, and its working groups. Note that 19 other groups may also distribute working documents as Internet- 20 Drafts. 22 Internet-Drafts are draft documents valid for a maximum of six months 23 and may be updated, replaced, or obsoleted by other documents at any 24 time. It is inappropriate to use Internet-Drafts as reference 25 material or to cite them other than as "work in progress." 27 The list of current Internet-Drafts can be accessed at 28 http://www.ietf.org/ietf/1id-abstracts.txt. 30 The list of Internet-Draft Shadow Directories can be accessed at 31 http://www.ietf.org/shadow.html. 33 This Internet-Draft will expire on August 31, 2009. 35 Copyright Notice 37 Copyright (c) 2009 IETF Trust and the persons identified as the 38 document authors. All rights reserved. 40 This document is subject to BCP 78 and the IETF Trust's Legal 41 Provisions Relating to IETF Documents in effect on the date of 42 publication of this document (http://trustee.ietf.org/license-info). 43 Please review these documents carefully, as they describe your rights 44 and restrictions with respect to this document. 46 Abstract 48 OSPFv2 and OSPFv3 include a reliable flooding mechanism to 49 disseminate routing topology and Traffic Engineering (TE) information 50 within a routing domain. Given the effectiveness of these 51 mechanisms, it is convenient to envision using the same mechanism for 52 dissemination of other types of information within the domain. 53 However, burdening OSPF with this additional information will impact 54 intra-domain routing convergence and possibly jeopardize the 55 stability of the OSPF routing domain. This document presents 56 mechanism to relegate this ancillary information to a separate OSPF 57 instance and minimize the impact. 59 Table of Contents 61 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 62 1.1. Requirements notation . . . . . . . . . . . . . . . . . . 3 63 2. OSPF Transport Instance . . . . . . . . . . . . . . . . . . . 4 64 2.1. OSPFv2 Transport Instance Packets Differentiation . . . . 4 65 2.2. OSPFv3 Transport Instance Packets Differentiation . . . . 4 66 2.3. Instance Relationship to Normal OSPF Instances . . . . . . 4 67 2.3.1. Ships in the Night Relationship to Normal OSPF 68 Instances . . . . . . . . . . . . . . . . . . . . . . 4 69 2.3.2. Tigher Coupling with Normal OSPF Instances . . . . . . 5 70 2.4. Network Prioritization . . . . . . . . . . . . . . . . . . 5 71 2.5. OSPF Transport Instance Omission of Routing Calculation . 5 72 2.6. Non-routing Instance Separation . . . . . . . . . . . . . 5 73 2.7. Non-Routing Sparse Topologies . . . . . . . . . . . . . . 6 74 2.7.1. Remote OSPF Neighbor . . . . . . . . . . . . . . . . . 7 75 3. OSPF Transport Instance Information Encoding . . . . . . . . . 8 76 3.1. OSPFv2 Transport Instance Information Encoding . . . . . . 8 77 3.2. OSPFv3 Transport Instance Information Encoding . . . . . . 8 78 4. Security Considerations . . . . . . . . . . . . . . . . . . . 9 79 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 80 6. Normative References . . . . . . . . . . . . . . . . . . . . . 11 81 Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . . 12 82 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13 84 1. Introduction 86 OSPFv2 [OSPFV2] and OSPFv3 [OSPFV3] include a reliable flooding 87 mechanism to disseminate routing topology and Traffic Engineering 88 (TE) information within a routing domain. Given the effectiveness of 89 these mechanisms, it is convenient to envision using the same 90 mechanism for dissemination of other types of information within the 91 domain. However, burdening OSPF with this additional information 92 will impact intra-domain routing convergence and possibly jeopardize 93 the stability of the OSPF routing domain. This document presents 94 mechanism to relegate this ancillary information to a separate OSPF 95 instance and minimize the impact. 97 1.1. Requirements notation 99 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 100 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 101 document are to be interpreted as described in [RFC-KEYWORDS]. 103 2. OSPF Transport Instance 105 In order to isolate the overhead of flooding non-routing information, 106 its flooding will be relegated to a separate protocol instance. This 107 instance should be given lower priority when contending for router 108 resources including processing, backplane bandwidth, and line card 109 bandwidth. How that is realized is an implementation issue and is 110 beyond the scope of this document. 112 2.1. OSPFv2 Transport Instance Packets Differentiation 114 OSPFv2 currently doesn't offer a mechanism to differentiate Transport 115 instance packets from normal instance packets sent and received on 116 the same interface. However, the [MULTI-INST] provides the necessary 117 packet encoding to support multiple OSPF protocol instances. 119 2.2. OSPFv3 Transport Instance Packets Differentiation 121 Fortunately, OSPFv3 already supports separate instances within the 122 packet encodings. The existing OSPFv3 packet header instance ID 123 field will be used to differentiate packets received on the same link 124 (refer to section 2.4 in [OSPFV3]). 126 2.3. Instance Relationship to Normal OSPF Instances 128 There are basically two alternatives for the relationship between a 129 normal OSPF instance and a Transport Instance. In both cases, we 130 must guarantee that any information we've received is treated as 131 valid if and only if the router sending it is reachable. We'll refer 132 to this as the "condition of reachability" in this document. 134 1. Ships in the Night - The Transport Instance has no relationship 135 or dependency on any other OSPF instance. 137 2. Child Instance - The Transport Instance has a child-parent 138 relationship with a normal OSPF instance and is dependent on this 139 for topology information and assuring the "condition of 140 reachability". 142 2.3.1. Ships in the Night Relationship to Normal OSPF Instances 144 In this mode, the Transport Instance is not dependent on any other 145 OSPF instance. It does, however, have much of the overhead as 146 topology information must be advertised to satisfy the condition of 147 reachability. 149 Prefix information does this need to be advertised. This implies 150 that for OSPFv2, only router-LSAs, network-LSAs, and type 4 summary- 151 LSAs need to be advertised. In the router-LSAs, the stub (type 3) 152 links may be suppressed. For OSPFv3, this implies that router-LSAs, 153 Network-LSAs, and inter-area-router-LSAs must be advertised. 155 2.3.2. Tigher Coupling with Normal OSPF Instances 157 Further optimization and coupling between the transport instance and 158 a normal OSPF instance are beyond the scope of this document. This 159 is an area for future study. 161 2.4. Network Prioritization 163 While OSPFv2 (section 4.3 in [OSPFV2]) are normally sent with IP 164 precedence Internetwork Control, any packets sent by a transport 165 instance will be sent with IP precedence Flash (B'011'). This is 166 only appropriate given that this is a pretty flashy mechanism. 168 Similarly, OSPFv3 transport instance packets will be sent with the 169 traffic class mapped to flash (B'011') as specified in ([OSPFV3]. 171 By setting the IP/IPv6 precedence differently for OSPF transport 172 instance packets, normal OSPF routing instances can be given priority 173 during both packet transmission and reception. In fact, Some router 174 implemenations map the IP precedence directly to their internal 175 packet priority. However, implementation issues are beyond the scope 176 of this document. 178 2.5. OSPF Transport Instance Omission of Routing Calculation 180 Since the whole point of the transport instance is to separate the 181 routing and non-routing processing and fate-sharing, a transport 182 instance SHOULD NOT install any routes. OSPF routers SHOULD NOT 183 advertise any transport instance LSAs containing IP or IPv6 prefixes 184 and OSPF routers receiving LSAs advertising prefixes SHOULD ignore 185 them. This implies that an OSPFv2 transport instance Link State 186 Database should not include any Summary-LSAs (type 3) , AS-External- 187 LSAs (type 5), or NSSA-LSAs (type 7) and the Router-LSAs should not 188 include any stub (type 3) links. An OSPFv3 transport instance Link 189 State database should not include any Inter-Area-Prefix-LSAs (type 190 0x2003), AS-External-LSAs (0x4005), NSSA-LSAs (type 0x2007), or 191 Intra-Area-Prefix-LSAs (type 0x2009). If they are erroneously 192 advertised, they MUST be ignored by OSPF routers supporting this 193 specification. 195 2.6. Non-routing Instance Separation 197 It has been suggested that an implementatin could obtain the same 198 level of separation between IP routing information and non-routing 199 information in a single instance with slight modifications to the 200 OSPF protocol. The authors refute this contention for the following 201 reasons: 203 o Adding internal and external mechanisms to prioritize routing 204 information over non-routing information are much more complex 205 than simply relegating the non-routing information to a separate 206 instance as proposed in this specification. 208 o The instance boundary offers much better separation for allocation 209 of finite resources such as buffers, memory, processor cores, 210 sockets, and bandwidth. 212 o The instance boundary decreases the level of fate sharing for 213 failures. Each instance may be implemented as a separate process 214 or task. 216 o With non-routing information, many times not every router in the 217 OSPF routing domain requires knowledge of every piece of routing 218 information. In these cases, groups of routers which need to 219 share information can be segregated into sparse topologies greatly 220 reducing the amount of non-routing information any single router 221 needs to maintain. 223 2.7. Non-Routing Sparse Topologies 225 With non-routing information, many times not every router in the OSPF 226 routing domain requires knowledge of every piece of routing 227 information. In these cases, groups of routers which need to share 228 information can be segregated into sparse topologies. This will 229 greatly reduce the amount of information any single router needs to 230 maintain with the core routers possibly not requiring any non-routing 231 information at all. 233 With normal OSPF, every router in an OSPF area must have every piece 234 of topological and IP or IPv6 prefix routing information. With non- 235 routing information, only the routers needing to share a set of 236 information need be part of the corresponding sparse topology. For 237 directly attached routers, one only need to configure the esired 238 topologies on the interfaces with routers requiring the non-routing 239 information. When the routers making up the sparse topology are not 240 part of a uniconnected graph, two alternatives exist. The first 241 alternative is configure tunnels to form a fully connected graph 242 including only those routers in the sparse topology. The second 243 alternative is use remote neighbors as described in Section 2.7.1. 245 2.7.1. Remote OSPF Neighbor 247 With sparse topologies, OSPF routers sharing non-routing information 248 may not be directly connected. OSPF adjacencies with remote 249 neighbors are formed exactly as they are with regular OSPF neighbors. 250 The main difference is that a remote OSPF neighbor's address is 251 configured and IP routing is used to deliver packet to the remote 252 neighbor. Other salient feature of remote neighbor include: 254 o All OSPF packets are addressed to the remote neighbor's configured 255 IP address. 257 o The adjacency is represented in the router Router-LSA as a router 258 (type-1) link with the link data set to the remote neighbor 259 address. 261 o Similar to NBMA networks, a poll-interval is configured to 262 determine if the remote neighbor is reachable. This value is 263 normally much higher than the hello interval. 265 3. OSPF Transport Instance Information Encoding 267 The format of the TLVs within the body of an LSA containing non- 268 routing information is the same as the format used by the Traffic 269 Engineering Extensions to OSPF [TE]. The LSA payload consists of one 270 or more nested Type/Length/Value (TLV) triplets. The format of each 271 TLV is: 273 0 1 2 3 274 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 1 275 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 276 | Type | Length | 277 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 278 | Value... | 279 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 281 TLV Format 283 However, each unique application using the mechanisms defined in this 284 document will have it's own unique ID. Whether to encode this ID as 285 the top-level TLV or make it part of the OSPF LSA ID is open for 286 debate. 288 The specific TLVs and sub-TLVs relating to a given application and 289 the corresponding IANA considerations MUST for standard applications 290 MUST be specified in the document corresponding to that application. 292 3.1. OSPFv2 Transport Instance Information Encoding 294 Application specific information will be flooded in opaque LSAs as 295 specified in [OPAQUE]. 297 3.2. OSPFv3 Transport Instance Information Encoding 299 Application specific information will be flooded in separate LSAs 300 with separate function codes. Refer to section A.4.2.1 of [OSPFV3] 301 for information on the LS Type encoding in OSPFv3. 303 4. Security Considerations 305 The security considerations for the Transport Instance will not be 306 different for those for OSPFv2 [OSPFV2] and OSPFv3 [OSPFV3]. 308 5. IANA Considerations 310 No new IANA assignments are required for this draft. 312 6. Normative References 314 [MULTI-INST] 315 Lindem, A., Mirtorabi, S., and A. Roy, "OSPF Multi- 316 Instance Extensions", 317 draft-acee-ospf-multi-instance-02.txt (work in progress). 319 [OPAQUE] Berger, L., Bryskin, I., Zinin, A., and R. Coltun, "The 320 OSPF Opaque LSA Option", RFC 5250, July 2008. 322 [OSPFV2] Moy, J., "OSPF Version 2", RFC 2328, April 1998. 324 [OSPFV3] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 325 for IPv6", RFC 5340, July 2008. 327 [RFC-KEYWORDS] 328 Bradner, S., "Key words for use in RFC's to Indicate 329 Requirement Levels", RFC 2119, March 1997. 331 [TE] Katz, D., Yeung, D., and K. Kompella, "Traffic Engineering 332 Extensions to OSPF", RFC 3630, September 2003. 334 Appendix A. Acknowledgments 336 The RFC text was produced using Marshall Rose's xml2rfc tool. 338 Authors' Addresses 340 Acee Lindem 341 Redback Networks 342 102 Carric Bend Court 343 Cary, NC 27519 344 USA 346 Email: acee@redback.com 348 Abhay Roy 349 Cisco Systems 350 225 West Tasman Drive 351 San Jose, CA 95134 352 USA 354 Email: akr@cisco.com 356 Sina Mirtorabi 357 Cisco Systems 358 3 West Plumeria Drive 359 San Jose, CA 95134 360 USA 362 Email: sina@cisco.com