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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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-11) exists of draft-ietf-bfd-seamless-base-09 Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 1 comment (--).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 29, 2016 Ionos Networks 6 S. Aldrin 7 Huawei Technologies 8 T. Ranganath 9 Nokia 10 April 27, 2016 12 OSPF Extensions to Advertise Seamless Bidirectional Forwarding Detection 13 (S-BFD) Target Discriminators 14 draft-ietf-ospf-sbfd-discriminator-05 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 29, 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 . . . . . . . . . . . . . . . . . . . . . . 6 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 flooding scope for S-BFD discriminator information advertised 156 through OSPF can be limited to one or more OSPF areas, or can be 157 extended across the entire OSPF routing domain. 159 Note that the S-BFD session may be required to span multiple areas, 160 in which case the flooding scope may comprise these areas. This 161 could be the case for an ABR, for instance, advertising the S-BFD 162 discriminator information within the backbone area and/or a subset of 163 its attached IGP area(s). 165 The S-BFD Discriminator TLV is advertised within OSPFv2 Router 166 Information LSAs (Opaque type of 4 and Opaque ID of 0) or OSPFv3 167 Router Information LSAs (function code of 12), which are defined in 168 [RFC7770]. As such, elements of procedure are inherited from those 169 defined in [RFC7770]. 171 In OSPFv2, the flooding scope is controlled by the opaque LSA type 172 (as defined in [RFC5250]) and in OSPFv3, by the S1/S2 bits (as 173 defined in [RFC5340]). If the flooding scope is area local, then the 174 S-BFD Discriminator TLV MUST be carried within an OSPFv2 type 10 175 router information LSA or an OSPFV3 Router Information LSA with the 176 S1 bit set and the S2 bit clear. If the flooding scope is the entire 177 IGP domain, then the S-BFD Discriminator TLV MUST be carried within 178 an OSPFv2 type 11 Router Information LSA or OSPFv3 Router Information 179 LSA with the S1 bit clear and the S2 bit set. 181 When the S-BFD Reflector is deactivated, the OSPF speaker advertising 182 this S-BFD discriminator MUST originate a new Router Information LSA 183 that no longer includes the corresponding S-BFD Discriminator TLV, 184 provided there are other TLVs in the LSA. If there are no other TLVs 185 in the LSA, it MUST either send an empty Router Information LSA or 186 purge it by prematurely ageing it. 188 For intra-area reachability, the S-BFD Discriminator TLV information 189 regarding a specific target identifier is only considered current and 190 useable when the router advertising this information is itself 191 reachable via OSPF calculated paths in the same area of the LSA in 192 which the S-BFD Discriminator TLV appears. In the case of domain- 193 wide flooding, i.e., where the originator is sitting in a remote 194 area, the mechanism described in section 5 of [RFC5250] should be 195 used. 197 A change in information in the S-BFD Discriminator TLV MUST NOT 198 trigger any SPF computation at a receiving router. 200 3. Backward Compatibility 202 The S-BFD Discriminator TLV defined in this document does not 203 introduce any interoperability issues. 205 A router not supporting the S-BFD Discriminator TLV will just 206 silently ignore the TLV as specified in [RFC7770]. 208 4. Security Considerations 210 This document defines OSPF extensions to distribute the S-BFD 211 discriminator within an administrative domain. Hence the security of 212 the S-BFD discriminator distribution relies on the security of OSPF. 214 OSPF provides no encryption mechanism for protecting the privacy of 215 LSAs and, in particular, the privacy of the S-BFD discriminator 216 advertisement information. This however is not a concern as there 217 isn't any need to hide the discriminator value that can be used to 218 reach the Reflectors. 220 5. IANA Considerations 222 IANA has defined a registry for TLVs carried in the Router 223 Information LSA defined in [RFC7770]. IANA needs to assign a new TLV 224 codepoint for the S-BFD Discriminator TLV carried within the Router 225 Information LSA. 227 Value TLV Name Reference 228 ----- -------- ---------- 229 TBD S-BFD (this document) 230 Discriminator 232 6. Acknowledgements 234 The authors would like to thank Nobo Akiya, Les Ginsberg, Mach Chen 235 and Peter Psenak for insightful comments and useful suggestions. 237 7. References 239 7.1. Normative References 241 [I-D.ietf-bfd-seamless-base] 242 Akiya, N., Pignataro, C., Ward, D., Bhatia, M., and J. 243 Networks, "Seamless Bidirectional Forwarding Detection 244 (S-BFD)", draft-ietf-bfd-seamless-base-09 (work in 245 progress), April 2016. 247 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 248 Requirement Levels", BCP 14, RFC 2119, 249 DOI 10.17487/RFC2119, March 1997, 250 . 252 [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, 253 DOI 10.17487/RFC2328, April 1998, 254 . 256 [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 257 for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, 258 . 260 [RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and 261 S. Shaffer, "Extensions to OSPF for Advertising Optional 262 Router Capabilities", RFC 7770, DOI 10.17487/RFC7770, 263 February 2016, . 265 7.2. Informative References 267 [RFC5250] Berger, L., Bryskin, I., Zinin, A., and R. Coltun, "The 268 OSPF Opaque LSA Option", RFC 5250, DOI 10.17487/RFC5250, 269 July 2008, . 271 Authors' Addresses 273 Carlos Pignataro 274 Cisco Systems, Inc. 276 Email: cpignata@cisco.com 277 Manav Bhatia 278 Ionos Networks 280 Email: manav@ionosnetworks.com 282 Sam Aldrin 283 Huawei Technologies 285 Email: aldrin.ietf@gmail.com 287 Trilok Ranganath 288 Nokia 290 Email: trilok.ranganatha@nokia.com