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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references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 7752 (Obsoleted by RFC 9552) == Outdated reference: A later version (-22) exists of draft-ietf-spring-segment-routing-policy-02 Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Inter-Domain Routing Z. Li 3 Internet-Draft Huawei 4 Intended status: Standards Track S. Aldrin 5 Expires: August 26, 2019 Google, Inc 6 J. Tantsura 7 Apstra 8 G. Mirsky 9 ZTE Corp. 10 S. Zhuang 11 Huawei 12 K. Talaulikar 13 Cisco Systems 14 February 22, 2019 16 BGP Link-State Extensions for Seamless BFD 17 draft-li-idr-bgp-ls-sbfd-extensions-03 19 Abstract 21 Seamless Bidirectional Forwarding Detection (S-BFD) defines a 22 simplified mechanism to use Bidirectional Forwarding Detection (BFD) 23 with large portions of negotiation aspects eliminated, thus providing 24 benefits such as quick provisioning as well as improved control and 25 flexibility to network nodes initiating the path monitoring. The 26 link-state routing protocols (IS-IS and OSPF) have been extended to 27 advertise the Seamless BFD (S-BFD) Discriminators. 29 This draft defines extensions to the BGP Link-state address-family to 30 carry the S-BFD Discriminators information via BGP. 32 Requirements Language 34 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 35 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 36 "OPTIONAL" in this document are to be interpreted as described in BCP 37 14 [RFC2119] [RFC8174] when, and only when, they appear in all 38 capitals, as shown here. 40 Status of This Memo 42 This Internet-Draft is submitted in full conformance with the 43 provisions of BCP 78 and BCP 79. 45 Internet-Drafts are working documents of the Internet Engineering 46 Task Force (IETF). Note that other groups may also distribute 47 working documents as Internet-Drafts. The list of current Internet- 48 Drafts is at https://datatracker.ietf.org/drafts/current/. 50 Internet-Drafts are draft documents valid for a maximum of six months 51 and may be updated, replaced, or obsoleted by other documents at any 52 time. It is inappropriate to use Internet-Drafts as reference 53 material or to cite them other than as "work in progress." 55 This Internet-Draft will expire on August 26, 2019. 57 Copyright Notice 59 Copyright (c) 2019 IETF Trust and the persons identified as the 60 document authors. All rights reserved. 62 This document is subject to BCP 78 and the IETF Trust's Legal 63 Provisions Relating to IETF Documents 64 (https://trustee.ietf.org/license-info) in effect on the date of 65 publication of this document. Please review these documents 66 carefully, as they describe your rights and restrictions with respect 67 to this document. Code Components extracted from this document must 68 include Simplified BSD License text as described in Section 4.e of 69 the Trust Legal Provisions and are provided without warranty as 70 described in the Simplified BSD License. 72 Table of Contents 74 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 75 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 76 3. Problem and Requirement . . . . . . . . . . . . . . . . . . . 3 77 4. BGP-LS Extensions for S-BFD Discriminator . . . . . . . . . . 4 78 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 79 6. Manageability Considerations . . . . . . . . . . . . . . . . 6 80 6.1. Operational Considerations . . . . . . . . . . . . . . . 6 81 6.2. Management Considerations . . . . . . . . . . . . . . . . 6 82 7. Security Considerations . . . . . . . . . . . . . . . . . . . 6 83 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7 84 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 85 9.1. Normative References . . . . . . . . . . . . . . . . . . 7 86 9.2. Informative References . . . . . . . . . . . . . . . . . 7 87 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 89 1. Introduction 91 Seamless Bidirectional Forwarding Detection (S-BFD) [RFC7880] defines 92 a simplified mechanism to use Bidirectional Forwarding Detection 93 (BFD) [RFC5880] with large portions of negotiation aspects 94 eliminated, thus providing benefits such as quick provisioning as 95 well as improved control and flexibility to network nodes initiating 96 the path monitoring. 98 For monitoring of a service path end-to-end via S-BFD, the headend/ 99 initiator node needs to know the S-BFD Discriminator of the 100 destination/tail-end node of that service. The link-state routing 101 protocols (IS-IS, OSPF and OSPFv3) have been extended to advertise 102 the S-BFD Discriminators. With this a initiator node can learn the 103 S-BFD discriminator for all nodes within its IGP area/level or 104 optionally within the domain. With networks being divided into 105 multiple IGP domains for scaling and operational considerations, the 106 service endpoints that require end to end S-BFD monitoring often span 107 across IGP domains. 109 BGP Link-State (BGP-LS) [RFC7752] enables the collection and 110 distribution of IGP link-state topology information via BGP sessions 111 across IGP areas/levels and domains. The S-BFD discriminator(s) of a 112 node can thus be distributed along with the topology information via 113 BGP-LS across IGP domains and even across multiple Autonomous Systems 114 (AS) within an administrative domain. 116 This draft defines extensions to BGP-LS for carrying the S-BFD 117 Discriminators information. 119 2. Terminology 121 This memo makes use of the terms defined in [RFC7880]. 123 3. Problem and Requirement 125 Seamless MPLS [I-D.ietf-mpls-seamless-mpls] extends the core domain 126 and integrates aggregation and access domains into a single MPLS 127 domain. In a large network, the core and aggregation networks can be 128 organized as different ASes. Although the core and aggregation 129 networks are segmented into different ASes, an E2E LSP can be created 130 using hierarchical BGP signaled LSPs based on iBGP labeled unicast 131 within each AS, and eBGP labeled unicast to extend the LSP across AS 132 boundaries. This provides a seamless MPLS transport connectivity for 133 any two service end-points across the entire domain. In order to 134 detect failures for such end to end services and trigger faster 135 protection and/or re-routing, S-BFD MAY be used for the Service Layer 136 (e.g. for MPLS VPNs, PW, etc. ) or the Transport Layer monitoring. 137 This brings up the need for setting up S-BFD session spanning across 138 AS domains. 140 In a similar Segment Routing (SR) [RFC8402] multi-domain network, an 141 end to end SR Policy [I-D.ietf-spring-segment-routing-policy] path 142 may be provisioned between service end-points across domains either 143 via local provisioning or by a controller or signalled from a Path 144 Computation Engine (PCE). Monitoring using S-BFD can similarly be 145 setup for such a SR Policy. 147 Extending the automatic discovery of S-BFD discriminators of nodes 148 from within the IGP domain to across the administrative domain using 149 BGP-LS enables setting up of S-BFD sessions on demand across IGP 150 domains. The S-BFD discriminators for service end point nodes MAY be 151 learnt by the PCE or a controller via the BGP-LS feed that it gets 152 from across IGP domains and it can signal or provision the remote 153 S-BFD discriminator on the initiator node on demand when S-BFD 154 monitoring is required. The mechanisms for the signaling of the 155 S-BFD discriminator from the PCE/controller to the initiator node and 156 setup of the S-BFD session is outside the scope of this document. 158 Additionally, the service end-points themselves MAY also learn the 159 S-BFD discriminator of the remote nodes themselves by receiving the 160 BGP-LS feed via a route reflector (RR) or a centralized BGP Speaker 161 that is consolidating the topology information across the domains. 162 The initiator node can then itself setup the S-BFD session to the 163 remote node without a controller/PCE assistance. 165 While this document takes examples of MPLS and SR paths, the S-BFD 166 discriminator advertisement mechanism is applicable for any S-BFD 167 use-case in general. 169 4. BGP-LS Extensions for S-BFD Discriminator 171 The BGP-LS [RFC7752] specifies the Node NLRI for advertisement of 172 nodes and their attributes using the BGP-LS Attribute. The S-BFD 173 discriminators of a node are considered as its node level attribute 174 and advertised as such. 176 This document defines a new BGP-LS Attribute TLV called the S-BFD 177 Discriminators TLV and its format is as follows: 179 0 1 2 3 180 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 1 181 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 182 | Type | Length | 183 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 184 | Discriminator 1 | 185 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 186 | Discriminator 2 (Optional) | 187 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 188 | ... | 189 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 190 | Discriminator n (Optional) | 191 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 193 Figure 1: S-BFD Discriminators TLV 195 where: 197 o Type: TBD (see IANA Considerations Section 5) 199 o Length: variable. Minimum of 8 octets and increments of 4 octets 200 there on for each additional discriminator 202 o Discriminators : multiples of 4 octets, each carrying a S-BFD 203 local discriminator value of the node. At least one discriminator 204 MUST be included in the TLV. 206 The S-BFD Discriminators TLV can only be added to the BGP-LS 207 Attribute associated with the Node NLRI that originates the 208 corresponding underlying IGP TLV/sub-TLV as described below. This 209 information is derived from the protocol specific advertisements as 210 below.. 212 o IS-IS, as defined by the S-BFD Discriminators sub-TLV in 213 [RFC7883]. 215 o OSPFv2/OSPFv3, as defined by the S-BFD Discriminators TLV in 216 [RFC7884]. 218 When the node is not running any of the IGPs but running a protocol 219 like BGP, then the locally provisioned S-BFD discriminators of the 220 node MAY be originated as part of the BGP-LS attribute within the 221 Node NLRI corresponding to the local node. 223 5. IANA Considerations 225 This document requests assigning code-points from the registry "BGP- 226 LS Node Descriptor, Link Descriptor, Prefix Descriptor, and Attribute 227 TLVs" based on table below. The column "IS-IS TLV/Sub-TLV" defined 228 in the registry does not require any value and should be left empty. 230 +---------------+--------------------------+----------+ 231 | Code Point | Description | Length | 232 +---------------+--------------------------+----------+ 233 | TBD | S-BFD Discriminators TLV | variable | 234 +---------------+--------------------------+----------+ 236 6. Manageability Considerations 238 This section is structured as recommended in [RFC5706]. 240 The new protocol extensions introduced in this document augment the 241 existing IGP topology information that was distributed via [RFC7752]. 242 Procedures and protocol extensions defined in this document do not 243 affect the BGP protocol operations and management other than as 244 discussed in the Manageability Considerations section of [RFC7752]. 245 Specifically, the malformed NLRIs attribute tests in the Fault 246 Management section of [RFC7752] now encompass the new TLVs for the 247 BGP-LS NLRI in this document. 249 6.1. Operational Considerations 251 No additional operation considerations are defined in this document. 253 6.2. Management Considerations 255 No additional management considerations are defined in this document. 257 7. Security Considerations 259 The new protocol extensions introduced in this document augment the 260 existing IGP topology information that was distributed via [RFC7752]. 261 Procedures and protocol extensions defined in this document do not 262 affect the BGP security model other than as discussed in the Security 263 Considerations section of [RFC7752]. More specifically the aspects 264 related to limiting the nodes and consumers with which the topology 265 information is shared via BGP-LS to trusted entities within an 266 administrative domain. 268 Advertising the S-BFD Discriminators via BGP-LS makes it possible for 269 attackers to initiate S-BFD sessions using the advertised 270 information. The vulnerabilities this poses and how to mitigate them 271 are discussed in [RFC7752]. 273 8. Acknowledgements 275 The authors would like to thank Nan Wu for his contributions to this 276 work. 278 9. References 280 9.1. Normative References 282 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 283 Requirement Levels", BCP 14, RFC 2119, 284 DOI 10.17487/RFC2119, March 1997, 285 . 287 [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and 288 S. Ray, "North-Bound Distribution of Link-State and 289 Traffic Engineering (TE) Information Using BGP", RFC 7752, 290 DOI 10.17487/RFC7752, March 2016, 291 . 293 [RFC7880] Pignataro, C., Ward, D., Akiya, N., Bhatia, M., and S. 294 Pallagatti, "Seamless Bidirectional Forwarding Detection 295 (S-BFD)", RFC 7880, DOI 10.17487/RFC7880, July 2016, 296 . 298 [RFC7883] Ginsberg, L., Akiya, N., and M. Chen, "Advertising 299 Seamless Bidirectional Forwarding Detection (S-BFD) 300 Discriminators in IS-IS", RFC 7883, DOI 10.17487/RFC7883, 301 July 2016, . 303 [RFC7884] Pignataro, C., Bhatia, M., Aldrin, S., and T. Ranganath, 304 "OSPF Extensions to Advertise Seamless Bidirectional 305 Forwarding Detection (S-BFD) Target Discriminators", 306 RFC 7884, DOI 10.17487/RFC7884, July 2016, 307 . 309 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 310 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 311 May 2017, . 313 9.2. Informative References 315 [I-D.ietf-mpls-seamless-mpls] 316 Leymann, N., Decraene, B., Filsfils, C., Konstantynowicz, 317 M., and D. Steinberg, "Seamless MPLS Architecture", draft- 318 ietf-mpls-seamless-mpls-07 (work in progress), June 2014. 320 [I-D.ietf-spring-segment-routing-policy] 321 Filsfils, C., Sivabalan, S., daniel.voyer@bell.ca, d., 322 bogdanov@google.com, b., and P. Mattes, "Segment Routing 323 Policy Architecture", draft-ietf-spring-segment-routing- 324 policy-02 (work in progress), October 2018. 326 [RFC5706] Harrington, D., "Guidelines for Considering Operations and 327 Management of New Protocols and Protocol Extensions", 328 RFC 5706, DOI 10.17487/RFC5706, November 2009, 329 . 331 [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection 332 (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, 333 . 335 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 336 Decraene, B., Litkowski, S., and R. Shakir, "Segment 337 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 338 July 2018, . 340 Authors' Addresses 342 Zhenbin Li 343 Huawei 344 Huawei Bld., No.156 Beiqing Rd. 345 Beijing 100095 346 China 348 Email: lizhenbin@huawei.com 350 Sam Aldrin 351 Google, Inc 353 Email: aldrin.ietf@gmail.com 355 Jeff Tantsura 356 Apstra 358 Email: jefftant.ietf@gmail.com 359 Greg Mirsky 360 ZTE Corp. 362 Email: gregimirsky@gmail.com 364 Shunwan Zhuang 365 Huawei 366 Huawei Bld., No.156 Beiqing Rd. 367 Beijing 100095 368 China 370 Email: zhuangshunwan@huawei.com 372 Ketan Talaulikar 373 Cisco Systems 374 India 376 Email: ketant@cisco.com