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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) Summary: 1 error (**), 0 flaws (~~), 1 warning (==), 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 S. Zhuang 4 Intended status: Standards Track Huawei 5 Expires: November 6, 2022 K. Talaulikar, Ed. 6 Arrcus Inc 7 S. Aldrin 8 Google, Inc 9 J. Tantsura 10 Microsoft 11 G. Mirsky 12 Ericsson 13 May 5, 2022 15 BGP Link-State Extensions for Seamless BFD 16 draft-ietf-idr-bgp-ls-sbfd-extensions-10 18 Abstract 20 Seamless Bidirectional Forwarding Detection (S-BFD) defines a 21 simplified mechanism to use Bidirectional Forwarding Detection (BFD) 22 with large portions of negotiation aspects eliminated, thus providing 23 benefits such as quick provisioning as well as improved control and 24 flexibility to network nodes initiating the path monitoring. The 25 link-state routing protocols (IS-IS and OSPF) have been extended to 26 advertise the Seamless BFD (S-BFD) Discriminators. 28 This document defines extensions to the BGP Link-state address-family 29 to carry the S-BFD Discriminators' information via BGP. 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 https://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 6, 2022. 48 Copyright Notice 50 Copyright (c) 2022 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 (https://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. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 67 2.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 68 3. BGP-LS Extensions for S-BFD Discriminator . . . . . . . . . . 3 69 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 70 5. Manageability Considerations . . . . . . . . . . . . . . . . 5 71 6. Security Considerations . . . . . . . . . . . . . . . . . . . 5 72 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 73 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 74 8.1. Normative References . . . . . . . . . . . . . . . . . . 6 75 8.2. Informative References . . . . . . . . . . . . . . . . . 6 76 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 78 1. Introduction 80 Seamless Bidirectional Forwarding Detection (S-BFD) [RFC7880] defines 81 a simplified mechanism to use Bidirectional Forwarding Detection 82 (BFD) [RFC5880] with large portions of negotiation aspects 83 eliminated, thus providing benefits such as quick provisioning as 84 well as improved control and flexibility to network nodes initiating 85 the path monitoring. 87 For monitoring of a service path end-to-end via S-BFD, the headend 88 node (i.e. Initiator) needs to know the S-BFD Discriminator of the 89 destination/tail-end node (i.e. Responder) of that service. The 90 link-state routing protocols (IS-IS [RFC7883] and OSPF [RFC7884]) 91 have been extended to advertise the S-BFD Discriminators. With this, 92 an Initiator can learn the S-BFD discriminator for all Responders 93 within its IGP area/level, or optionally within the domain. With 94 networks being divided into multiple IGP domains for scaling and 95 operational considerations, the service endpoints that require end to 96 end S-BFD monitoring often span across IGP domains. 98 BGP Link-State (BGP-LS) [RFC7752] enables the collection and 99 distribution of IGP link-state topology information via BGP sessions 100 across IGP areas/levels and domains. The S-BFD discriminator(s) of a 101 node can thus be distributed along with the topology information via 102 BGP-LS across IGP domains and even across multiple Autonomous Systems 103 (AS) within an administrative domain. 105 This document defines extensions to BGP-LS for carrying the S-BFD 106 Discriminators information. 108 2. Terminology 110 This memo makes use of the terms defined in [RFC7880]. 112 2.1. Requirements Language 114 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 115 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 116 "OPTIONAL" in this document are to be interpreted as described in BCP 117 14 [RFC2119] [RFC8174] when, and only when, they appear in all 118 capitals, as shown here. 120 3. BGP-LS Extensions for S-BFD Discriminator 122 BGP-LS [RFC7752] specifies the Node Network Layer Reachability 123 Information (NLRI) for the advertisement of nodes and their 124 attributes using the BGP-LS Attribute. The S-BFD discriminators of a 125 node are considered a node-level attribute and advertised as such. 127 This document defines a new BGP-LS Attribute TLV called the S-BFD 128 Discriminators TLV and its format is as follows: 130 0 1 2 3 131 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 1 132 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 133 | Type | Length | 134 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 135 | Discriminator 1 | 136 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 137 | Discriminator 2 (Optional) | 138 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 139 | ... | 140 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 141 | Discriminator n (Optional) | 142 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 144 Figure 1: S-BFD Discriminators TLV 146 where: 148 o Type: 1032 150 o Length: variable. It MUST be a minimum of 4 octets and increments 151 by 4 octets for each additional discriminator. 153 o Discriminator n: 4 octets each, carrying an S-BFD local 154 discriminator value of the node. At least one discriminator MUST 155 be included in the TLV. 157 The S-BFD Discriminators TLV can be added to the BGP-LS Attribute 158 associated with the Node NLRI that originates the corresponding 159 underlying IGP TLV/sub-TLV as described below. This information is 160 derived from the protocol specific advertisements as follows: 162 o IS-IS, as defined by the S-BFD Discriminators sub-TLV in 163 [RFC7883]. 165 o OSPFv2/OSPFv3, as defined by the S-BFD Discriminator TLV in 166 [RFC7884]. 168 4. IANA Considerations 170 IANA is requested to permanently allocate the following code-point 171 from the "BGP-LS Node Descriptor, Link Descriptor, Prefix Descriptor, 172 and Attribute TLVs" registry. The column "IS-IS TLV/Sub-TLV" defined 173 in the registry does not require any value and should be left empty. 175 +------------+--------------------------+---------------+ 176 | Code Point | Description | Reference | 177 +------------+--------------------------+---------------+ 178 | 1032 | S-BFD Discriminators TLV | This document | 179 +---------------+--------------------------+------------+ 181 Table 1: S-BFD Discriminators TLV Code-Point Allocation 183 5. Manageability Considerations 185 The new protocol extensions introduced in this document augment the 186 existing IGP topology information that was distributed via BGP-LS 187 [RFC7752]. Procedures and protocol extensions defined in this 188 document do not affect the BGP protocol operations and management 189 other than as discussed in the Manageability Considerations section 190 of [RFC7752]. Specifically, the malformed NLRIs attribute tests in 191 the Fault Management section of [RFC7752] now encompass the new TLV 192 for the BGP-LS NLRI in this document. 194 6. Security Considerations 196 The new protocol extensions introduced in this document augment the 197 existing IGP topology information that can be distributed via BGP-LS 198 [RFC7752]. Procedures and protocol extensions defined in this 199 document do not affect the BGP security model other than as discussed 200 in the Security Considerations section of [RFC7752]. More 201 specifically, the aspects related to limiting the nodes and consumers 202 with which the topology information is shared via BGP-LS to trusted 203 entities within an administrative domain. 205 The TLV introduced in this document is used to propagate IGP defined 206 information ([RFC7883] and [RFC7884]). The TLV represents 207 information used to set up S-BFD sessions. The IGP instances 208 originating this information are assumed to support any required 209 security and authentication mechanisms (as described in [RFC7883] and 210 [RFC7884]). 212 Advertising the S-BFD Discriminators via BGP-LS makes it possible for 213 attackers to initiate S-BFD sessions using the advertised 214 information. The vulnerabilities this poses and how to mitigate them 215 are discussed in [RFC7880]. 217 7. Acknowledgements 219 The authors would like to thank Nan Wu for his contributions to this 220 work. The authors would also like to thank Gunter Van De Velde and 221 Thomas Fossati for their reviews. The authors would also like to 222 thank Jeff Haas for his shepherd review and Alvaro Retana for his AD 223 review of this document. 225 8. References 227 8.1. Normative References 229 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 230 Requirement Levels", BCP 14, RFC 2119, 231 DOI 10.17487/RFC2119, March 1997, 232 . 234 [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and 235 S. Ray, "North-Bound Distribution of Link-State and 236 Traffic Engineering (TE) Information Using BGP", RFC 7752, 237 DOI 10.17487/RFC7752, March 2016, 238 . 240 [RFC7880] Pignataro, C., Ward, D., Akiya, N., Bhatia, M., and S. 241 Pallagatti, "Seamless Bidirectional Forwarding Detection 242 (S-BFD)", RFC 7880, DOI 10.17487/RFC7880, July 2016, 243 . 245 [RFC7883] Ginsberg, L., Akiya, N., and M. Chen, "Advertising 246 Seamless Bidirectional Forwarding Detection (S-BFD) 247 Discriminators in IS-IS", RFC 7883, DOI 10.17487/RFC7883, 248 July 2016, . 250 [RFC7884] Pignataro, C., Bhatia, M., Aldrin, S., and T. Ranganath, 251 "OSPF Extensions to Advertise Seamless Bidirectional 252 Forwarding Detection (S-BFD) Target Discriminators", 253 RFC 7884, DOI 10.17487/RFC7884, July 2016, 254 . 256 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 257 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 258 May 2017, . 260 8.2. Informative References 262 [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection 263 (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, 264 . 266 Authors' Addresses 268 Zhenbin Li 269 Huawei 270 Huawei Bld., No.156 Beiqing Rd. 271 Beijing 100095 272 China 274 Email: lizhenbin@huawei.com 276 Shunwan Zhuang 277 Huawei 278 Huawei Bld., No.156 Beiqing Rd. 279 Beijing 100095 280 China 282 Email: zhuangshunwan@huawei.com 284 Ketan Talaulikar (editor) 285 Arrcus Inc 286 India 288 Email: ketant.ietf@gmail.com 290 Sam Aldrin 291 Google, Inc 293 Email: aldrin.ietf@gmail.com 295 Jeff Tantsura 296 Microsoft 298 Email: jefftant.ietf@gmail.com 300 Greg Mirsky 301 Ericsson 303 Email: gregimirsky@gmail.com