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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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-11) exists of draft-ietf-bfd-seamless-base-09 Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Internet Engineering Task Force C. Pignataro 3 Internet-Draft Cisco 4 Intended status: Standards Track M. Bhatia 5 Expires: October 31, 2016 Ionos Networks 6 S. Aldrin 7 Huawei Technologies 8 T. Ranganath 9 Nokia 10 April 29, 2016 12 OSPF Extensions to Advertise Seamless Bidirectional Forwarding Detection 13 (S-BFD) Target Discriminators 14 draft-ietf-ospf-sbfd-discriminator-06 16 Abstract 18 This document defines a new OSPF Router Information (RI) TLV that 19 allows OSPF routers to flood the Seamless Bidirectional Forwarding 20 Detection (S-BFD) discriminator values associated with a target 21 network identifier. This mechanism is applicable to both OSPFv2 and 22 OSPFv3. 24 Requirements Language 26 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 27 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 28 document are to be interpreted as described in RFC 2119 [RFC2119]. 30 Status of This Memo 32 This Internet-Draft is submitted in full conformance with the 33 provisions of BCP 78 and BCP 79. 35 Internet-Drafts are working documents of the Internet Engineering 36 Task Force (IETF). Note that other groups may also distribute 37 working documents as Internet-Drafts. The list of current Internet- 38 Drafts is at http://datatracker.ietf.org/drafts/current/. 40 Internet-Drafts are draft documents valid for a maximum of six months 41 and may be updated, replaced, or obsoleted by other documents at any 42 time. It is inappropriate to use Internet-Drafts as reference 43 material or to cite them other than as "work in progress." 45 This Internet-Draft will expire on October 31, 2016. 47 Copyright Notice 49 Copyright (c) 2016 IETF Trust and the persons identified as the 50 document authors. All rights reserved. 52 This document is subject to BCP 78 and the IETF Trust's Legal 53 Provisions Relating to IETF Documents 54 (http://trustee.ietf.org/license-info) in effect on the date of 55 publication of this document. Please review these documents 56 carefully, as they describe your rights and restrictions with respect 57 to this document. Code Components extracted from this document must 58 include Simplified BSD License text as described in Section 4.e of 59 the Trust Legal Provisions and are provided without warranty as 60 described in the Simplified BSD License. 62 Table of Contents 64 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 65 1.1. Relationship Between OSPF and S-BFD . . . . . . . . . . . 3 66 2. Implementation . . . . . . . . . . . . . . . . . . . . . . . 3 67 2.1. S-BFD Discriminator TLV . . . . . . . . . . . . . . . . . 3 68 2.2. Flooding Scope . . . . . . . . . . . . . . . . . . . . . 4 69 3. Backward Compatibility . . . . . . . . . . . . . . . . . . . 5 70 4. Security Considerations . . . . . . . . . . . . . . . . . . . 5 71 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 72 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 73 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 74 7.1. Normative References . . . . . . . . . . . . . . . . . . 6 75 7.2. Informative References . . . . . . . . . . . . . . . . . 6 76 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 78 1. Introduction 80 Seamless Bidirectional Forwarding Detection (S-BFD), specified in 81 [I-D.ietf-bfd-seamless-base], is a simplified mechanism for using 82 Bidirectional Forwarding Detection (BFD) with many negotiations 83 eliminated. This is achieved by using four-octet discriminators, 84 unique within an administrative domain, to identify the Network 85 Targets. These S-BFD discriminators can be advertised by the IGPs, 86 and this document concerns itself with OSPF. Specifically, this 87 document defines a new TLV (named the S-BFD Discriminator TLV) to be 88 carried within the OSPF Router Information (RI) Link State 89 Advertisement (LSA) ([RFC7770]). 91 1.1. Relationship Between OSPF and S-BFD 93 This document, implicitly, defines a relationship between OSPF and 94 S-BFD. S-BFD assigns one or more discriminators to each S-BFD 95 reflector node. OSPF, in turn, learns about these from S-BFD, and 96 floods them in the newly defined TLV. After this information is 97 flooded, it is stored in all the OSPF nodes such that S-BFD 98 initiators can map out target nodes to target discriminators, and can 99 therefore construct the S-BFD probe. 101 When multiple S-BFD discriminators are advertised, how a given 102 discriminator is mapped to a specific use case is out of scope for 103 this document. 105 2. Implementation 107 This extension makes use of the Router Information (RI) Opaque LSA, 108 defined in [RFC7770] , for both OSPFv2 [RFC2328] and OSPFv3 109 [RFC5340], by defining a new OSPF Router Information (RI) TLV: the 110 S-BFD Discriminator TLV. 112 The S-BFD Discriminator TLV is OPTIONAL. Upon receipt of the TLV, a 113 router may decide to install the S-BFD discriminator in BFD Target 114 Identifier Table. 116 In the presence of multiple instances of the OSPF/OSPFv3 RI LSA, the 117 S-BFD discriminators for an OSPF router are the union of all 118 discriminators advertised in all instances of the S-BFD Discriminator 119 TLV (see Section 2.1) in all advertised non-MaxAge OSPF RI LSAs. 121 2.1. S-BFD Discriminator TLV 123 The format of the S-BFD Discriminator TLV is as follows: 125 0 1 2 3 126 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 1 127 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 128 | Type | Length | 129 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 130 | Discriminator 1 | 131 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 132 | Discriminator 2 (Optional) | 133 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 134 | ... | 135 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 136 | Discriminator n (Optional) | 137 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 139 Type - S-BFD Discriminator TLV Type (TBD [to be filled in by IANA]) 141 Length - Total length of the discriminator(s) that appear in the 142 Value field, in octets. Each discriminator is 4 octets, so the 143 Length is 4 times the number of discriminators included in the TLV. 144 There is no optional padding for this field. 146 Discriminator(s) - The Value field of the TVL includes the S-BFD 147 network target discriminator value or values. 149 Routers that do not recognize the S-BFD Discriminator TLV Type will 150 ignore the TLV [RFC7770], and therefore will not learn S-BFD 151 discriminators via OSPF. 153 2.2. Flooding Scope 155 The S-BFD Discriminator TLV is advertised within OSPFv2 Router 156 Information LSAs (Opaque type of 4 and Opaque ID of 0) or OSPFv3 157 Router Information LSAs (function code of 12), which are defined in 158 [RFC7770]. As such, elements of procedure are inherited from those 159 defined in [RFC7770]. 161 In OSPFv2, the flooding scope is controlled by the opaque LSA type 162 (as defined in [RFC5250]) and in OSPFv3, by the S1/S2 bits (as 163 defined in [RFC5340]). If the flooding scope is area local, then the 164 S-BFD Discriminator TLV MUST be carried within an OSPFv2 type 10 165 router information LSA or an OSPFV3 Router Information LSA with the 166 S1 bit set and the S2 bit clear. If the flooding scope is the entire 167 IGP domain, then the S-BFD Discriminator TLV MUST be carried within 168 an OSPFv2 type 11 Router Information LSA or OSPFv3 Router Information 169 LSA with the S1 bit clear and the S2 bit set. 171 When the S-BFD Reflector is deactivated, the OSPF speaker advertising 172 this S-BFD discriminator MUST originate a new Router Information LSA 173 that no longer includes the corresponding S-BFD Discriminator TLV, 174 provided there are other TLVs in the LSA. If there are no other TLVs 175 in the LSA, it MUST either send an empty Router Information LSA or 176 purge it by prematurely ageing it. 178 For intra-area reachability, the S-BFD Discriminator TLV information 179 regarding a specific target identifier is only considered current and 180 useable when the router advertising this information is itself 181 reachable via OSPF calculated paths in the same area of the LSA in 182 which the S-BFD Discriminator TLV appears. In the case of domain- 183 wide flooding, i.e., where the originator is sitting in a remote 184 area, the mechanism described in section 5 of [RFC5250] should be 185 used. 187 Although the S-BFD discriminators may change when enabling the S-BFD 188 functionality or via an explicit configuration event, such changes 189 are expected to occur very rarely. Such a change in the information 190 will require S-BFD Discriminator TLV in OSPF to be advertised. 192 A change in information in the S-BFD Discriminator TLV MUST NOT 193 trigger any SPF computation at a receiving router. 195 3. Backward Compatibility 197 The S-BFD Discriminator TLV defined in this document does not 198 introduce any interoperability issues. 200 A router not supporting the S-BFD Discriminator TLV will just 201 silently ignore the TLV as specified in [RFC7770]. 203 4. Security Considerations 205 This document defines OSPF extensions to distribute the S-BFD 206 discriminator within an administrative domain. Hence the security of 207 the S-BFD discriminator distribution relies on the security of OSPF. 209 OSPF provides no encryption mechanism for protecting the privacy of 210 LSAs and, in particular, the privacy of the S-BFD discriminator 211 advertisement information. This however is not a concern as there 212 isn't any need to hide the discriminator value that can be used to 213 reach the Reflectors. 215 5. IANA Considerations 217 IANA has defined a registry for TLVs carried in the Router 218 Information LSA defined in [RFC7770]. IANA needs to assign a new TLV 219 codepoint for the S-BFD Discriminator TLV carried within the Router 220 Information LSA. 222 Value TLV Name Reference 223 ----- -------- ---------- 224 TBD S-BFD (this document) 225 Discriminator 227 6. Acknowledgements 229 The authors would like to thank Nobo Akiya, Les Ginsberg, Mach Chen 230 and Peter Psenak for insightful comments and useful suggestions. 232 7. References 234 7.1. Normative References 236 [I-D.ietf-bfd-seamless-base] 237 Akiya, N., Pignataro, C., Ward, D., Bhatia, M., and J. 238 Networks, "Seamless Bidirectional Forwarding Detection 239 (S-BFD)", draft-ietf-bfd-seamless-base-09 (work in 240 progress), April 2016. 242 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 243 Requirement Levels", BCP 14, RFC 2119, 244 DOI 10.17487/RFC2119, March 1997, 245 . 247 [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, 248 DOI 10.17487/RFC2328, April 1998, 249 . 251 [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 252 for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, 253 . 255 [RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and 256 S. Shaffer, "Extensions to OSPF for Advertising Optional 257 Router Capabilities", RFC 7770, DOI 10.17487/RFC7770, 258 February 2016, . 260 7.2. Informative References 262 [RFC5250] Berger, L., Bryskin, I., Zinin, A., and R. Coltun, "The 263 OSPF Opaque LSA Option", RFC 5250, DOI 10.17487/RFC5250, 264 July 2008, . 266 Authors' Addresses 268 Carlos Pignataro 269 Cisco Systems, Inc. 271 Email: cpignata@cisco.com 273 Manav Bhatia 274 Ionos Networks 276 Email: manav@ionosnetworks.com 277 Sam Aldrin 278 Huawei Technologies 280 Email: aldrin.ietf@gmail.com 282 Trilok Ranganath 283 Nokia 285 Email: trilok.ranganatha@nokia.com