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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: - If it's DROther or BDR for that link, SHOULD not take any action. - If receiving node is DR for the link, it MUST remove the originator of the link overload TLV from the list of connected neighbors and MUST re-originate the network LSA and flood into the OSPF area. -- The document date (July 16, 2015) is 2494 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references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 3137 (Obsoleted by RFC 6987) == Outdated reference: draft-ietf-ospf-ospfv3-lsa-extend has been published as RFC 8362 == Outdated reference: draft-ietf-ospf-prefix-link-attr has been published as RFC 7684 Summary: 2 errors (**), 0 flaws (~~), 4 warnings (==), 1 comment (--).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 P. Sarkar 4 Intended status: Standards Track H. Gredler 5 Expires: January 17, 2016 Juniper Networks, Inc. 6 M. Nanduri 7 Microsoft Corporation 8 L. Jalil 9 Verizon 10 July 16, 2015 12 OSPF Link Overload 13 draft-hegde-ospf-link-overload-01 15 Abstract 17 Many OSPFv2 or OSPFv3 deployments run on overlay networks provisioned 18 by means of pseudo-wires or L2-circuits. when the devices in the 19 underlying network go for maintenance, it is useful to divert the 20 traffic away from the node before the maintenance is actually 21 scheduled. Since the nodes in the underlying network are not visible 22 to OSPF, existing stub router mechanism described in [RFC3137] cannot 23 be used. It is useful for routers in OSPFv2 or OSPFv3 routing domain 24 to be able to advertise a link being in overload state to indicate 25 impending maintenance activity in the underlying network devices. 27 This document describes the protocol extensions to disseminate link 28 overload information in OSPFv2 and OSPFv3 protocol. 30 Requirements Language 32 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 33 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 34 document are to be interpreted as described in RFC 2119 [RFC2119]. 36 Status of This Memo 38 This Internet-Draft is submitted in full conformance with the 39 provisions of BCP 78 and BCP 79. 41 Internet-Drafts are working documents of the Internet Engineering 42 Task Force (IETF). Note that other groups may also distribute 43 working documents as Internet-Drafts. The list of current Internet- 44 Drafts is at http://datatracker.ietf.org/drafts/current/. 46 Internet-Drafts are draft documents valid for a maximum of six months 47 and may be updated, replaced, or obsoleted by other documents at any 48 time. It is inappropriate to use Internet-Drafts as reference 49 material or to cite them other than as "work in progress." 51 This Internet-Draft will expire on January 17, 2016. 53 Copyright Notice 55 Copyright (c) 2015 IETF Trust and the persons identified as the 56 document authors. All rights reserved. 58 This document is subject to BCP 78 and the IETF Trust's Legal 59 Provisions Relating to IETF Documents 60 (http://trustee.ietf.org/license-info) in effect on the date of 61 publication of this document. Please review these documents 62 carefully, as they describe your rights and restrictions with respect 63 to this document. Code Components extracted from this document must 64 include Simplified BSD License text as described in Section 4.e of 65 the Trust Legal Provisions and are provided without warranty as 66 described in the Simplified BSD License. 68 Table of Contents 70 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 71 2. Link overload sub TLV . . . . . . . . . . . . . . . . . . . . 3 72 2.1. OSPFv2 Link overload sub TLV . . . . . . . . . . . . . . 3 73 2.2. OSPFv3 Link overload sub TLV . . . . . . . . . . . . . . 3 74 3. Elements of procedure . . . . . . . . . . . . . . . . . . . . 4 75 3.1. Point-to-point links . . . . . . . . . . . . . . . . . . 4 76 3.2. Broadcast/NBMA links . . . . . . . . . . . . . . . . . . 4 77 3.3. Point-to-multipoint links . . . . . . . . . . . . . . . . 5 78 4. Backward compatibility . . . . . . . . . . . . . . . . . . . 5 79 5. Applications . . . . . . . . . . . . . . . . . . . . . . . . 5 80 5.1. Pseudowire Services . . . . . . . . . . . . . . . . . . . 5 81 5.2. Controller based Traffic Engineering Deployments . . . . 6 82 6. Security Considerations . . . . . . . . . . . . . . . . . . . 6 83 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 84 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7 85 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 86 9.1. Normative References . . . . . . . . . . . . . . . . . . 7 87 9.2. Informative References . . . . . . . . . . . . . . . . . 7 88 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 90 1. Introduction 92 It is useful for routers in OSPFv2 or OSPFv3 routing domain to be 93 able to advertise a link being in overload state to indicate 94 impending maintenance activity on the link. This document provides 95 mechanisms to advertise link overload state in the flexible encodings 96 provided by OSPFv2 Prefix/Link Attribute Advertisement( 97 [I-D.ietf-ospf-prefix-link-attr]) and OSPFv3 Extended LSA 98 ([I-D.ietf-ospf-ospfv3-lsa-extend]). Throughout this document, OSPF 99 is used when the text applies to both OSPFv2 and OSPFv3. OSPFv2 or 100 OSPFv3 is used when the text is specific to one version of the OSPF 101 protocol. 103 2. Link overload sub TLV 105 2.1. OSPFv2 Link overload sub TLV 107 Link overload sub TLV is carried as part of the Extended link TLV as 108 defined in [I-D.ietf-ospf-prefix-link-attr] for OSPFv2. 110 0 1 2 3 111 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 1 112 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 113 | Type | Length | 114 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 115 | Remote IP address | 116 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 118 Figure 1: Link overload sub TLV for OSPFv2 120 Type : TBA 122 Length: 4 124 Value: Remote IPv4 address. The remote IP4 address is used to 125 identify the particular link that is in overload state when there are 126 multiple parallel links between two nodes. 128 2.2. OSPFv3 Link overload sub TLV 130 Link overload sub TLV is carried in the Router-link TLV as defined in 131 the [I-D.ietf-ospf-ospfv3-lsa-extend] for OSPFv3. The Router-Link 132 TLV contains the neighbor interface-id and can uniquely identify the 133 link on the remote node. 135 0 1 2 3 136 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 1 137 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 138 | Type | Length | 139 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 141 Figure 2: Link overload sub TLV for OSPFv3 143 Type : TBA 145 Length: 0 147 3. Elements of procedure 149 The Link Overload sub TLV indicates that the Link which carries the 150 sub TLV is overloaded. The node that has the link going for 151 maintenance, sets metric of the link to MAX-METRIC and re-originates 152 the router LSA. The metric in the reverse direction also need to 153 change to divert the traffic from reverse direction. The node SHOULD 154 originate Link overload sub TLV and include it in Extended link TLV 155 and originate the Extended Link Opaque LSA as defined in 156 [I-D.ietf-ospf-prefix-link-attr] for OSPFv2 and E-Router-LSA as 157 defined in [I-D.ietf-ospf-ospfv3-lsa-extend] for OSPFv3 and flood in 158 the OSPF area. 160 when the originator of the Link Overload sub TLV, purges the extended 161 link opaque LSA or re-originates without the Link Overload sub TLV, 162 the metric on the remote node SHOULD be changed back to the original 163 value. 165 Based on the link type of the overloaded link below actions MAY be 166 taken by the receiver. 168 3.1. Point-to-point links 170 When a link overload TLV is received for a point-to-point link the 171 receiver SHOULD identify the local link which corresponds to the 172 overloaded link and set the metric to MAX-METRIC (0xffff). Receiver 173 node MUST re-originate the router-LSA with the changed metric and 174 flood into the OSPF area. 176 3.2. Broadcast/NBMA links 178 Broadcast or NBMA networks in OSPF are represented by a star topology 179 where the Designated Router (DR) is the central point to which all 180 other routers on the broadcast or NBMA network connect. As a result, 181 routers on the broadcast or NBMA network advertise only their 182 adjacency to the DR. Routers that do not act as DR do not form or 183 advertise adjacencies with each other. For the Broadcast links, the 184 MAX-METRIC on the outgoing link cannot be changed since all the 185 neighbors are on same link. Setting the link cost to MAX-METRIC 186 would impact paths going via all neighbors. 188 When a link-overload TLV is received by the remote end for a 189 broadcast/NBMA link 191 - If it's DROther or BDR for that link, SHOULD not take any action. 192 - If receiving node is DR for the link, it MUST remove the originator 193 of the link overload TLV from the list of connected neighbors and 194 MUST re-originate the network LSA and flood into the OSPF area. 196 3.3. Point-to-multipoint links 198 Operation for the point-to-multipoint links is similar to the point- 199 to-point links. When a link overload TLV is received for a point-to- 200 multipoint link the receiver SHOULD identify the neighbor which 201 corresponds to the overloaded link and set the metric to MAX-METRIC 202 (0xffff). Receiver node MUST re-originate the router-LSA with the 203 changed metric and flood into the OSPF area. 205 4. Backward compatibility 207 The mechanism described in the document is fully backward 208 compatible.It is required that the originator and receiver of link- 209 overload sub TLV understand the extensions defined in this document 210 and in case of broadcast links the originator and the DR need to 211 understand the extensions. Other nodes in the network compute based 212 on increased metric and hence the feature is backward compatible. 214 5. Applications 216 5.1. Pseudowire Services 218 ---------PE3----------------PE4---------- 219 | | 220 | | 221 CE1---------PE1----------------PE2---------CE2 222 | | 223 | | 224 ----------------------------------------- 225 Private VLAN 227 Figure 3: Pseudowire Services 229 Many service providers offer pseudo-wire services to customers using 230 L2 circuits. The IGP protocol that runs in the customer network 231 would also to run over the pseudo-wire to get seamless private 232 network for the customer. Service providers want to offer overload 233 kind of functionality when the PE device is taken-out for 234 maintenance.The provider should guarantee that the PE is taken out 235 for maintenance only after the service is successfully diverted on 236 the alternate path. Link overload feature provides facilities to 237 achieve this service by increasing the metric on the link but still 238 allowing the traffic to use the link when there is no alternate path 239 available. 241 5.2. Controller based Traffic Engineering Deployments 243 _____________ 244 | | 245 -------------| Controller |-------------- 246 | |____________ | | 247 | | 248 | ------- Primary Path --------------- | 249 PE1---------P1----------------P2---------PE2 250 | | 251 | | 252 |________P3________| 254 Alternate Path 256 Figure 4: Controller based Traffic Engineering 258 Controller based deployments where the controller participates in the 259 IGP protocol gets the link-overload information when the link 260 maintenance is impending. Using this information controller finds an 261 alternate path. If there are no alternate paths satisfying the 262 traffic engineering constraints, controller might temporarily relax 263 the constraints and put the service on different path. In the above 264 example when P1->P2 link goes for maintenance, controller gets the 265 link-overload information and sets up an alternate path via 266 P1->P3->P2. Once the traffic is diverted, P1->P2 link can be taken 267 out for maintenance/upgrade. 269 6. Security Considerations 271 This document does not introduce any further security issues other 272 than those discussed in [RFC2328] and [RFC5340]. 274 7. IANA Considerations 276 This specification updates one OSPF registry: 278 OSPF Extended Link TLVs Registry 280 i) TBD - Link Overload TLV OSPFV3 Router Link TLV Registry 282 i) TBD - Link Overload TLV 284 8. Acknowledgements 286 9. References 288 9.1. Normative References 290 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 291 Requirement Levels", BCP 14, RFC 2119, March 1997. 293 [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998. 295 [RFC3137] Retana, A., Nguyen, L., White, R., Zinin, A., and D. 296 McPherson, "OSPF Stub Router Advertisement", RFC 3137, 297 June 2001. 299 [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 300 for IPv6", RFC 5340, July 2008. 302 9.2. Informative References 304 [I-D.ietf-ospf-ospfv3-lsa-extend] 305 Lindem, A., Mirtorabi, S., Roy, A., and F. Baker, "OSPFv3 306 LSA Extendibility", draft-ietf-ospf-ospfv3-lsa-extend-06 307 (work in progress), February 2015. 309 [I-D.ietf-ospf-prefix-link-attr] 310 Psenak, P., Gredler, H., Shakir, R., Henderickx, W., 311 Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute 312 Advertisement", draft-ietf-ospf-prefix-link-attr-03 (work 313 in progress), February 2015. 315 Authors' Addresses 316 Shraddha Hegde 317 Juniper Networks, Inc. 318 Embassy Business Park 319 Bangalore, KA 560093 320 India 322 Email: shraddha@juniper.net 324 Pushpasis Sarkar 325 Juniper Networks, Inc. 326 Embassy Business Park 327 Bangalore, KA 560093 328 India 330 Email: psarkar@juniper.net 332 Hannes Gredler 333 Juniper Networks, Inc. 334 1194 N. Mathilda Ave. 335 Sunnyvale, CA 94089 336 US 338 Email: hannes@juniper.net 340 Mohan Nanduri 341 Microsoft Corporation 342 One Microsoft Way 343 Redmond, WA 98052 344 US 346 Email: mnanduri@microsoft.com 348 Luay Jalil 349 Verizon 351 Email: luay.jalil@verizon.com