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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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-11) exists of draft-ietf-bfd-seamless-base-04 ** Obsolete normative reference: RFC 4970 (Obsoleted by RFC 7770) Summary: 1 error (**), 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 M. Bhatia 3 Internet-Draft Ionos Networks 4 Intended status: Standards Track C. Pignataro 5 Expires: March 27, 2016 Cisco Systems 6 S. Aldrin 7 Huawei Technologies 8 T. Ranganath 9 Alcatel-Lucent 10 September 24, 2015 12 OSPF extensions to advertise S-BFD Target Discriminator 13 draft-ietf-ospf-sbfd-discriminator-02 15 Abstract 17 This document defines a new OSPF Router Information (RI) TLV that 18 allows OSPF routers to flood the S-BFD discriminator values 19 associated with a target network identifier. This mechanism is 20 applicable to both OSPFv2 and OSPFv3. 22 Requirements Language 24 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 25 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 26 document are to be interpreted as described in RFC 2119 [RFC2119]. 28 Status of This Memo 30 This Internet-Draft is submitted in full conformance with the 31 provisions of BCP 78 and BCP 79. 33 Internet-Drafts are working documents of the Internet Engineering 34 Task Force (IETF). Note that other groups may also distribute 35 working documents as Internet-Drafts. The list of current Internet- 36 Drafts is at http://datatracker.ietf.org/drafts/current/. 38 Internet-Drafts are draft documents valid for a maximum of six months 39 and may be updated, replaced, or obsoleted by other documents at any 40 time. It is inappropriate to use Internet-Drafts as reference 41 material or to cite them other than as "work in progress." 43 This Internet-Draft will expire on March 27, 2016. 45 Copyright Notice 47 Copyright (c) 2015 IETF Trust and the persons identified as the 48 document authors. All rights reserved. 50 This document is subject to BCP 78 and the IETF Trust's Legal 51 Provisions Relating to IETF Documents 52 (http://trustee.ietf.org/license-info) in effect on the date of 53 publication of this document. Please review these documents 54 carefully, as they describe your rights and restrictions with respect 55 to this document. Code Components extracted from this document must 56 include Simplified BSD License text as described in Section 4.e of 57 the Trust Legal Provisions and are provided without warranty as 58 described in the Simplified BSD License. 60 Table of Contents 62 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 63 1.1. Relationship between OSPF and S-BFD . . . . . . . . . . . 2 64 2. Implementation . . . . . . . . . . . . . . . . . . . . . . . 3 65 2.1. S-BFD Discriminator TLV . . . . . . . . . . . . . . . . . 3 66 2.2. Flooding Scope . . . . . . . . . . . . . . . . . . . . . 4 67 3. Backward Compatibility . . . . . . . . . . . . . . . . . . . 5 68 4. Security Considerations . . . . . . . . . . . . . . . . . . . 5 69 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 70 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 71 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 72 7.1. Normative References . . . . . . . . . . . . . . . . . . 5 73 7.2. Informative References . . . . . . . . . . . . . . . . . 6 74 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 76 1. Introduction 78 Seamless Bidirectional Forwarding Detection (S-BFD), specified in 79 [I-D.ietf-bfd-seamless-base], is a simplified mechanism for using BFD 80 with many negotiations eliminated. This is achieved by using unique 81 network-wide discriminators to identify the Network Targets (e.g., IP 82 addresses). These S-BFD discriminators can be advertised by the 83 IGPs, and this document concerns itself with OSPF. Specifically, 84 this document defines a new TLV (named the S-BFD Discriminator TLV) 85 to be carried within the OSPF Router Information LSA ([RFC4970]). 87 1.1. Relationship between OSPF and S-BFD 89 This document, implicitly, defines a relationship between OSPF and 90 S-BFD. S-BFD assigns one or more Discriminators to each S-BFD 91 reflector node. OSPF, in turn, learns about these from S-BFD, and 92 floods them in the newly defined TLV. After this information is 93 flooded, it is stored in all the OSPF nodes such that S-BFD 94 initiators can map out target nodes to target Discriminators, and can 95 therefore construct the S-BFD probe. 97 2. Implementation 99 This extension makes use of the Router Information (RI) Opaque LSA, 100 defined in [RFC4970] , for both OSPFv2 [RFC2328] and OSPFv3 101 [RFC5340], by defining a new OSPF Router Information (RI) TLV: the 102 S-BFD Discriminator TLV. 104 The S-BFD Discriminator TLV is OPTIONAL. Upon receipt of the TLV, a 105 router may decide to ignore this TLV or install the S-BFD 106 discriminator in BFD Target Identifier Table. 108 In the presence of multiple instances of the OSPF/OSPFv3 RI LSA, the 109 S-BFD Discriminators for an OSPF router are the superset of all 110 Discriminators advertised in all instances of the S-BFD Discriminator 111 TLV (see Section 2.1) in all advertised non-MaxAge OSPF RI LSAs. 113 2.1. S-BFD Discriminator TLV 115 The format of the S-BFD Discriminator TLV is as follows: 117 0 1 2 3 118 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 1 119 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 120 | Type | Length | 121 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 122 | Discriminator 1 | 123 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 124 | Discriminator 2 (Optional) | 125 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 126 | ... | 127 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 128 | Discriminator n (Optional) | 129 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 131 Type - S-BFD Discriminator TLV Type 133 Length - Total length of the discriminator (Value field) in octets, 134 not including the optional padding. The Length is a multiple of 4 135 octets, and consequently specifies how many Discriminators are 136 included in the TLV. 138 Value - S-BFD network target discriminator value or values. 140 Routers that do not recognize the S-BFD Discriminator TLV Type MUST 141 ignore the TLV. S-BFD discriminator is associated with the BFD 142 Target Identifier type, that allows demultiplexing to a specific task 143 or service. 145 2.2. Flooding Scope 147 The flooding scope for S-BFD Discriminator information advertised 148 through OSPF can be limited to one or more OSPF areas, or can be 149 extended across the entire OSPF routing domain. 151 Note that the S-BFD session may be required to pan multiple areas, in 152 which case the flooding scope may comprise these areas. This could 153 be the case for an ABR, for instance, advertising the S-BFD 154 Discriminator information within the backbone area and/or a subset of 155 its attached IGP area(s). 157 The S-BFD Discriminator TLV is advertised within OSPFv2 Router 158 Information LSAs (Opaque type of 4 and Opaque ID of 0) or OSPFv3 159 Router Information LSAs (function code of 12), which are defined in 160 [RFC4970]. As such, elements of procedure are inherited from those 161 defined in [RFC4970]. 163 In OSPFv2, the flooding scope is controlled by the opaque LSA type 164 (as defined in [RFC5250]) and in OSPFv3, by the S1/S2 bits (as 165 defined in [RFC5340]). If the flooding scope is area local, then the 166 S-BFD Discriminator TLV MUST be carried within an OSPFv2 type 10 167 router information LSA or an OSPFV3 Router Information LSA with the 168 S1 bit set and the S2 bit clear. If the flooding scope is the entire 169 IGP domain, then the S-BFD Discriminator TLV MUST be carried within 170 an OSPFv2 type 11 Router Information LSA or OSPFv3 Router Information 171 LSA with the S1 bit clear and the S2 bit set. 173 When the S-BFD Reflector is deactivated, the OSPF speaker advertising 174 this S-BFD Discriminator MUST originate a new Router Information LSA 175 that no longer includes the corresponding S-BFD Discriminator TLV, 176 provided there are other TLVs in the LSA. If there are no other TLVs 177 in the LSA, it MUST either send an empty Router Information LSA or 178 purge it by prematurely ageing it. 180 For intra-area reachability, the S-BFD Discriminator TLV information 181 regarding a specific target identifier is only considered current and 182 useable when the router advertising this information is itself 183 reachable via OSPF calculated paths in the same area of the LSA in 184 which the S-BFD Discriminator TLV appears. In the case of domain- 185 wide flooding, i.e., where the originator is sitting in a remote 186 area, the mechanism described in section 5 of [RFC5250] should be 187 used. 189 A change in information in the S-BFD Discriminator TLV MUST NOT 190 trigger any SPF computation at a receiving router. 192 3. Backward Compatibility 194 The S-BFD Discriminator TLV defined in this document does not 195 introduce any interoperability issues. 197 A router not supporting the S-BFD Discriminator TLV will just 198 silently ignore the TLV as specified in [RFC4970]. 200 4. Security Considerations 202 This document defines OSPF extensions to distribute the S-BFD 203 discriminator within an administrative domain. Hence the security of 204 the S-BFD discriminator distribution relies on the security of OSPF. 206 OSPF provides no encryption mechanism for protecting the privacy of 207 LSAs and, in particular, the privacy of the S-BFD discriminator 208 advertisement information. This however is not a concern as there 209 isn't any need to hide the discriminator value that can be used to 210 reach the Reflectors. 212 5. IANA Considerations 214 IANA has defined a registry for TLVs carried in the Router 215 Information LSA defined in [RFC4970]. IANA needs to assign a new TLV 216 codepoint for the S-BFD Discriminator TLV carried within the Router 217 Information LSA. 219 Value TLV Name Reference 220 ----- -------- ---------- 221 TBD S-BFD (this document) 222 Discriminator 224 6. Acknowledgements 226 The authors would like to thank Nobo Akiya, Les Ginsberg, Mach Chen 227 and Peter Psenak for insightful comments and useful suggestions. 229 7. References 231 7.1. Normative References 233 [I-D.ietf-bfd-seamless-base] 234 Akiya, N., Pignataro, C., Ward, D., Bhatia, M., and J. 235 Networks, "Seamless Bidirectional Forwarding Detection 236 (S-BFD)", draft-ietf-bfd-seamless-base-04 (work in 237 progress), January 2015. 239 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 240 Requirement Levels", BCP 14, RFC 2119, March 1997. 242 [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998. 244 [RFC4970] Lindem, A., Shen, N., Vasseur, JP., Aggarwal, R., and S. 245 Shaffer, "Extensions to OSPF for Advertising Optional 246 Router Capabilities", RFC 4970, July 2007. 248 [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 249 for IPv6", RFC 5340, July 2008. 251 7.2. Informative References 253 [RFC5250] Berger, L., Bryskin, I., Zinin, A., and R. Coltun, "The 254 OSPF Opaque LSA Option", RFC 5250, July 2008. 256 Authors' Addresses 258 Manav Bhatia 259 Ionos Networks 261 Email: manav@ionosnetworks.com 263 Carlos Pignataro 264 Cisco Systems 266 Email: cpignata@cisco.com 268 Sam Aldrin 269 Huawei Technologies 271 Email: aldrin.ietf@gmail.com 273 Trilok Ranganath 274 Alcatel-Lucent 276 Email: trilok.ranganatha@alcatel-lucent.com