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Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == Using lowercase 'not' together with uppercase 'MUST', 'SHALL', 'SHOULD', or 'RECOMMENDED' is not an accepted usage according to RFC 2119. Please use uppercase 'NOT' together with RFC 2119 keywords (if that is what you mean). Found 'SHOULD not' in this paragraph: Each tag SHOULD be treated as an independent identifier that MAY be used in policy to perform a policy action. Whether or not tag A precedes or succeeds tag B SHOULD not change the meaning of the tag set. -- The document date (June 26, 2014) is 3563 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references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 4970 (Obsoleted by RFC 7770) == Outdated reference: A later version (-11) exists of draft-ietf-rtgwg-remote-lfa-02 Summary: 2 errors (**), 0 flaws (~~), 3 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Open Shortest Path First IGP S. Hegde 3 Internet-Draft H. Raghuveer 4 Intended status: Standards Track H. Gredler 5 Expires: December 28, 2014 Juniper Networks, Inc. 6 R. Shakir 7 British Telecom 8 A. Smirnov 9 Cisco Systems, Inc. 10 Z. Li 11 Huawei Technologies 12 June 26, 2014 14 Advertising per-node administrative tags in OSPF 15 draft-hegde-ospf-node-admin-tag-02 17 Abstract 19 This document describes an extension to OSPF protocol [RFC2328] to 20 add an optional operational capability, that allows tagging and 21 grouping of the nodes in an OSPF domain. This allows 22 simplification,ease of management and control over route and path 23 selection based on configured policies. 25 This document describes the protocol extensions to disseminate per- 26 node admin-tags to the OSPFv2 and OSPFv3 protocol. 28 Requirements Language 30 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 31 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 32 document are to be interpreted as described in RFC 2119 [RFC2119]. 34 Status of This Memo 36 This Internet-Draft is submitted in full conformance with the 37 provisions of BCP 78 and BCP 79. 39 Internet-Drafts are working documents of the Internet Engineering 40 Task Force (IETF). Note that other groups may also distribute 41 working documents as Internet-Drafts. The list of current Internet- 42 Drafts is at http://datatracker.ietf.org/drafts/current/. 44 Internet-Drafts are draft documents valid for a maximum of six months 45 and may be updated, replaced, or obsoleted by other documents at any 46 time. It is inappropriate to use Internet-Drafts as reference 47 material or to cite them other than as "work in progress." 48 This Internet-Draft will expire on December 28, 2014. 50 Copyright Notice 52 Copyright (c) 2014 IETF Trust and the persons identified as the 53 document authors. All rights reserved. 55 This document is subject to BCP 78 and the IETF Trust's Legal 56 Provisions Relating to IETF Documents 57 (http://trustee.ietf.org/license-info) in effect on the date of 58 publication of this document. Please review these documents 59 carefully, as they describe your rights and restrictions with respect 60 to this document. Code Components extracted from this document must 61 include Simplified BSD License text as described in Section 4.e of 62 the Trust Legal Provisions and are provided without warranty as 63 described in the Simplified BSD License. 65 Table of Contents 67 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 68 2. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 2 69 3. Administrative Tag TLV . . . . . . . . . . . . . . . . . . . 3 70 4. OSPF per-node administrative tag TLV . . . . . . . . . . . . 3 71 4.1. TLV format . . . . . . . . . . . . . . . . . . . . . . . 3 72 4.2. Elements of procedure . . . . . . . . . . . . . . . . . . 4 73 5. Applications . . . . . . . . . . . . . . . . . . . . . . . . 5 74 6. Security Considerations . . . . . . . . . . . . . . . . . . . 8 75 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 76 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9 77 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 78 9.1. Normative References . . . . . . . . . . . . . . . . . . 9 79 9.2. Informative References . . . . . . . . . . . . . . . . . 9 80 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 82 1. Introduction 84 This document provides mechanisms to advertise per-node 85 administrative tags in the OSPF Router Information LSA [RFC4970]. In 86 certain path-selection applications like for example in traffic- 87 engineering or LFA backup selection there is a need to tag the nodes 88 based on their roles in the network and have policies to prefer or 89 prune a certain group of nodes. 91 2. Applicability 93 For the purpose of advertising per-node administrative tags within 94 OSPF a new TLV is proposed. Because path selection is a functional 95 set which applies both to TE and non-TE applications, this new TLV is 96 carried in the Router Information LSA (RI LSA) [RFC4970] 98 3. Administrative Tag TLV 100 An administrative Tag is a 32-bit integer value that can be used to 101 identify a group of nodes in the OSPF domain. 103 The new TLV defined will be carried within an RI LSA for OSPFV2 and 104 OSPFV3. Router information LSA [RFC4970] can have link,area or AS 105 level flooding scope. Choosing the flooding scope to flood the group 106 tags are defined by the policies and is a local matter. 108 The TLV specifies one or more administrative tag values. An OSPF 109 node advertises the set of groups it is part of in the OSPF domain. 110 (for example, all PE-nodes are configured with certain tag value, all 111 P-nodes are configured with a different tag value in a domain). The 112 total number of admin tags that a given router can advertise at one 113 time is restricted to 64. If more tags are needed in future, multi- 114 instancing of the RI LSA [RFC4970] may be required. 116 4. OSPF per-node administrative tag TLV 118 4.1. TLV format 120 The format of the TLVs within the body of an RI LSA is the same as 121 the format used by the Traffic Engineering Extensions to OSPF 122 [RFC3630]. 124 The LSA payload consists of one or more nested Type/Length/Value 125 (TLV) triplets. The format of each TLV is: 127 0 1 2 3 128 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 1 129 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 130 | Type | Length | 131 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 132 | Administrative Tag #1 | 133 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 134 | Administrative Tag #2 | 135 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 136 // // 137 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 138 | Administrative Tag #N | 139 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 141 Figure 1: OSPF per-node Administrative Tag TLV 143 Type : TBA 145 Length: A 16-bit field that indicates the length of the value portion 146 in octets and will be a multiple of 4 octets dependent on the number 147 of tags advertised. 149 Value: A sequence of multiple 4 octets defining the administrative 150 tags. The number of tags carried in this TLV is restricted to 64. 152 4.2. Elements of procedure 154 Meaning of the Node administrative tags is generally opaque to OSPF. 155 Router advertising the Node administrative tag (or tags) may be 156 configured to do so without knowing (or even explicitly supporting) 157 functionality implied by the tag. 159 Interpretation of the tag values is implementation-specific. The 160 meaning of a Node administrative tag is defined by the network local 161 policy and is controlled via the configuration. There are no tag 162 values defined by this specification. 164 The semantics of the tag order has no meaning. That is, there is no 165 implied meaning to the ordering of the tags that indicates a certain 166 operation or set of operations that need to be performed based on the 167 ordering. 169 Each tag SHOULD be treated as an independent identifier that MAY be 170 used in policy to perform a policy action. Whether or not tag A 171 precedes or succeeds tag B SHOULD not change the meaning of the tag 172 set. 174 To avoid incomplete or inconsistent interpretations of the Node 175 administrative tags the same tag value MUST NOT be advertised by a 176 router in RI LSAs of different scopes. The same tag MAY be 177 advertised in multiple RI LSAs of the same scope, for example, OSPF 178 Area Border Router (ABR) may advertise the same tag in area-scope RI 179 LSAs in multiple areas connected to the ABR. 181 The Node administrative tags are not meant to be extended by the 182 future OSPF standards. The new OSPF extensions MUST NOT require use 183 of Node administrative tags or define well-known tag values. 184 Instead, the future OSPF extensions must define their own data 185 signaling tailored to the needs of the feature. 187 Being part of the RI LSA, the Node administrative tag TLV must be 188 reasonably small and stable. In particular, but not limited to, 189 implementations supporting the Node administrative tags MUST NOT tie 190 advertised tags to changes in the network topology (both within and 191 outside the OSPF domain) or reachability of routes. 193 5. Applications 195 This section lists several examples of how implementations might use 196 the Node administrative tags. These examples are given only to 197 demonstrate generic usefulness of the router tagging mechanism. 198 Implementation supporting this specification is not required to 199 implement any of the use cases. It is also worth noting that in some 200 described use cases routers configured to advertise tags help other 201 routers in their calculations but do not themselves implement the 202 same functionality. 204 1. Service auto-discovery 206 Router tagging may be used to automatically discover group of 207 routers sharing a particular service. 209 For example, service provider might desire to establish full mesh 210 of MPLS TE tunnels between all PE routers in the area of MPLS VPN 211 network. Marking all PE routers with a tag and configuring 212 devices with a policy to create MPLS TE tunnels to all other 213 devices advertising this tag will automate maintenance of the 214 full mesh. When new PE router is added to the area, all other PE 215 devices will open TE tunnels to it without the need of 216 reconfiguring them. 218 2. Fast-Rerouting policy 220 Increased deployment of Loop Free Alternates (LFA) as defined in 221 [RFC5286] poses operation and management challenges. 223 [I-D.litkowski-rtgwg-lfa-manageability] proposes policies which, 224 when implemented, will ease LFA operation concerns. 226 One of the proposed refinements is to be able to group the nodes 227 in IGP domain with administrative tags and engineer the LFA based 228 on configured policies. 230 (a) Administrative limitation of LFA scope 232 Service provider access infrastructure is frequently designed 233 in layered approach with each layer of devices serving 234 different purposes and thus having different hardware 235 capabilities and configured software features. When LFA 236 repair paths are being computed, it may be desirable to 237 exclude devices from being considered as LFA candidates based 238 on their layer. 240 For example, if the access infrastructure is divided into the 241 Access, Distribution and Core layers it may be desirable for 242 a Distribution device to compute LFA only via Distribution or 243 Core devices but not via Access devices. This may be due to 244 features enabled on Access routers; due to capacity 245 limitations or due to the security requirements. Managing 246 such a policy via configuration of the router computing LFA 247 is cumbersome and error prone. 249 With the Node administrative tags it is possible to assign a 250 tag to each layer and implement LFA policy of computing LFA 251 repair paths only via neighbors which advertise the Core or 252 Distribution tag. This requires minimal per-node 253 configuration and network automatically adapts when new links 254 or routers are added. 256 (b) LFA calculation optimization 258 Calculation of LFA paths may require significant resources of 259 the router. One execution of Dijkstra algorithm is required 260 for each neighbor eligible to become next hop of repair 261 paths. Thus a router with a few hundreds of neighbors may 262 need to execute the algorithm hundreds of times before the 263 best (or even valid) repair path is found. Manually 264 excluding from the calculation neighbors which are known to 265 provide no valid LFA (such as single-connected routers) may 266 significantly reduce number of Dijkstra algorithm runs. 268 LFA calculation policy may be configured so that routers 269 advertising certain tag value are excluded from LFA 270 calculation even if they are otherwise suitable. 272 3. Controlling Remote LFA tunnel termination 274 [I-D.ietf-rtgwg-remote-lfa] proposed method of tunneling traffic 275 after connected link failure to extend the basic LFA coverage and 276 algorithm to find tunnel tail-end routers fitting LFA 277 requirement. In most cases proposed algorithm finds more than 278 one candidate tail-end router. In real life network it may be 279 desirable to exclude some nodes from the list of candidates based 280 on the local policy. This may be either due to known limitations 281 of the node (the router does accept targeted LDP sessions 282 required to implement Remote LFA tunneling) or due to 283 administrative requirements (for example, it may be desirable to 284 choose tail-end router among co-located devices). 286 The Node administrative tag delivers simple and scalable 287 solution. Remote LFA can be configured with a policy to accept 288 during the tail-end router calculation as candidates only routers 289 advertising certain tag. Tagging routers allows to both exclude 290 nodes not capable of serving as Remote LFA tunnel tail-ends and 291 to define a region from which tail-end router must be selected. 293 4. Mobile backhaul network service deployment 295 The topology of mobile backhaul network usually adopts ring 296 topology to save fiber resource and it is divided into the 297 aggregate network and the access network. Cell Site 298 Gateways(CSGs) connects the eNodeBs and RNC(Radio Network 299 Controller) Site Gateways(RSGs)connects the RNCs. The mobile 300 traffic is transported from CSGs to RSGs. The network takes a 301 typical aggregate traffic model that more than one access rings 302 will attach to one pair of aggregate site gateways(ASGs) and more 303 than one aggregate rings will attach to one pair of RSGs. 305 ---------------- 306 / \ 307 / \ 308 / \ 309 +------+ +----+ Access +----+ 310 |eNodeB|---|CSG1| Ring 1 |ASG1|------------- 311 +------+ +----+ +----+ \ 312 \ / \ 313 \ / +----+ +---+ 314 \ +----+ |RSG1|----|RNC| 315 -------------| | Aggregate +----+ +---+ 316 |ASG2| Ring | 317 -------------| | +----+ +---+ 318 / +----+ |RSG2|----|RNC| 319 / \ +----+ +---+ 320 / \ / 321 +------+ +----+ Access +----+ / 322 |eNodeB|---|CSG2| Ring 2 |ASG3|------------ 323 +------+ +----+ +----+ 324 \ / 325 \ / 326 \ / 327 ----------------- 329 Figure 2: Mobile Backhaul Network 331 A typical mobile backhaul network with access rings and aggregate 332 links is shown in figure above. The mobile backhaul networks 333 deploy traffic engineering due to the strict Service Level 334 Agreements(SLA). The TE paths may have additional constraints to 335 avoid passing via different access rings or to get completely 336 disjoint backup TE paths. The mobile backhaul networks towards 337 the access side change frequently due to the growing mobile 338 traffic and addition of new eNodeBs. It's complex to satisfy the 339 requirements using cost, link color or explicit path 340 configurations. The node administrative tag defined in this 341 document can be effectively used to solve the problem for mobile 342 backhaul networks. The nodes in different rings can be assigned 343 with specific tags. TE path computation can be enhanced to 344 consider additional constraints based on node administrative 345 tags. 347 6. Security Considerations 349 This document does not introduce any further security issues other 350 than those discussed in [RFC2328] and [RFC5340]. 352 7. IANA Considerations 354 IANA maintains the registry for the TLVs. OSPF Administrative Tags 355 will require one new type code for the TLV defined in this document. 357 8. Acknowledgments 359 Thanks to Bharath R and Pushpasis Sarakar for useful inputs. Thanks 360 to Chris Bowers for providing useful inputs to remove ambiguity 361 related to tag-ordering. 363 9. References 365 9.1. Normative References 367 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 368 Requirement Levels", BCP 14, RFC 2119, March 1997. 370 [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998. 372 [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering 373 (TE) Extensions to OSPF Version 2", RFC 3630, September 374 2003. 376 [RFC4970] Lindem, A., Shen, N., Vasseur, JP., Aggarwal, R., and S. 377 Shaffer, "Extensions to OSPF for Advertising Optional 378 Router Capabilities", RFC 4970, July 2007. 380 [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 381 for IPv6", RFC 5340, July 2008. 383 9.2. Informative References 385 [I-D.ietf-rtgwg-remote-lfa] 386 Bryant, S., Filsfils, C., Previdi, S., Shand, M., and S. 387 Ning, "Remote LFA FRR", draft-ietf-rtgwg-remote-lfa-02 388 (work in progress), May 2013. 390 [I-D.litkowski-rtgwg-lfa-manageability] 391 Litkowski, S., Decraene, B., Filsfils, C., and K. Raza, 392 "Operational management of Loop Free Alternates", draft- 393 litkowski-rtgwg-lfa-manageability-01 (work in progress), 394 February 2013. 396 [RFC5286] Atlas, A. and A. Zinin, "Basic Specification for IP Fast 397 Reroute: Loop-Free Alternates", RFC 5286, September 2008. 399 Authors' Addresses 401 Shraddha Hegde 402 Juniper Networks, Inc. 403 Embassy Business Park 404 Bangalore, KA 560093 405 India 407 Email: shraddha@juniper.net 409 Harish Raghuveer 410 Juniper Networks, Inc. 411 Embassy Business Park 412 Bangalore 560093 413 India 415 Email: hraghuveer@juniper.net 417 Hannes Gredler 418 Juniper Networks, Inc. 419 1194 N. Mathilda Ave. 420 Sunnyvale, CA 94089 421 US 423 Email: hannes@juniper.net 425 Rob Shakir 426 British Telecom 428 Email: rob.shakir@bt.com 430 Anton Smirnov 431 Cisco Systems, Inc. 432 De Kleetlaan 6a 433 Diegem 1831 434 Belgium 436 Email: as@cisco.com 437 Li Zhenbin 438 Huawei Technologies 439 Huawei Bld. No.156 Beiqing Rd 440 Beijing 100095 441 China 443 Email: lizhenbin@huawei.com