idnits 2.17.1 draft-ietf-ospf-sbfd-discriminator-04.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (April 13, 2016) is 2933 days in the past. Is this intentional? 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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-11) exists of draft-ietf-bfd-seamless-base-08 Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 1 comment (--).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 M. Bhatia 3 Internet-Draft Ionos Networks 4 Intended status: Standards Track C. Pignataro 5 Expires: October 15, 2016 Cisco Systems 6 S. Aldrin 7 Huawei Technologies 8 T. Ranganath 9 Alcatel-Lucent 10 April 13, 2016 12 OSPF extensions to advertise S-BFD Target Discriminator 13 draft-ietf-ospf-sbfd-discriminator-04 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 October 15, 2016. 45 Copyright Notice 47 Copyright (c) 2016 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 . . . . . . . . . . . . . . . . . . . . . . . . . 6 72 7.1. Normative References . . . . . . . . . . . . . . . . . . 6 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 ([RFC7770]). 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 When multiple S-BFD Discriminators are advertised, how a given 98 Discriminator is mapped to a specific use case is out of scope for 99 this document. 101 2. Implementation 103 This extension makes use of the Router Information (RI) Opaque LSA, 104 defined in [RFC7770] , for both OSPFv2 [RFC2328] and OSPFv3 105 [RFC5340], by defining a new OSPF Router Information (RI) TLV: the 106 S-BFD Discriminator TLV. 108 The S-BFD Discriminator TLV is OPTIONAL. Upon receipt of the TLV, a 109 router may decide to ignore this TLV or install the S-BFD 110 discriminator in BFD Target Identifier Table. 112 In the presence of multiple instances of the OSPF/OSPFv3 RI LSA, the 113 S-BFD Discriminators for an OSPF router are the superset of all 114 Discriminators advertised in all instances of the S-BFD Discriminator 115 TLV (see Section 2.1) in all advertised non-MaxAge OSPF RI LSAs. 117 2.1. S-BFD Discriminator TLV 119 The format of the S-BFD Discriminator TLV is as follows: 121 0 1 2 3 122 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 1 123 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 124 | Type | Length | 125 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 126 | Discriminator 1 | 127 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 128 | Discriminator 2 (Optional) | 129 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 130 | ... | 131 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 132 | Discriminator n (Optional) | 133 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 135 Type - S-BFD Discriminator TLV Type 137 Length - Total length of the discriminator (Value field) in octets, 138 not including the optional padding. The Length is a multiple of 4 139 octets, and consequently specifies how many Discriminators are 140 included in the TLV. 142 Value - S-BFD network target discriminator value or values. 144 Routers that do not recognize the S-BFD Discriminator TLV Type will 145 ignore the TLV [RFC7770], and therefore will not learn S-BFD 146 Discriminators via OSPF. S-BFD discriminator is associated with the 147 BFD Target Identifier type, that allows demultiplexing to a specific 148 task or service. 150 2.2. Flooding Scope 152 The flooding scope for S-BFD Discriminator information advertised 153 through OSPF can be limited to one or more OSPF areas, or can be 154 extended across the entire OSPF routing domain. 156 Note that the S-BFD session may be required to pan multiple areas, in 157 which case the flooding scope may comprise these areas. This could 158 be the case for an ABR, for instance, advertising the S-BFD 159 Discriminator information within the backbone area and/or a subset of 160 its attached IGP area(s). 162 The S-BFD Discriminator TLV is advertised within OSPFv2 Router 163 Information LSAs (Opaque type of 4 and Opaque ID of 0) or OSPFv3 164 Router Information LSAs (function code of 12), which are defined in 165 [RFC7770]. As such, elements of procedure are inherited from those 166 defined in [RFC7770]. 168 In OSPFv2, the flooding scope is controlled by the opaque LSA type 169 (as defined in [RFC5250]) and in OSPFv3, by the S1/S2 bits (as 170 defined in [RFC5340]). If the flooding scope is area local, then the 171 S-BFD Discriminator TLV MUST be carried within an OSPFv2 type 10 172 router information LSA or an OSPFV3 Router Information LSA with the 173 S1 bit set and the S2 bit clear. If the flooding scope is the entire 174 IGP domain, then the S-BFD Discriminator TLV MUST be carried within 175 an OSPFv2 type 11 Router Information LSA or OSPFv3 Router Information 176 LSA with the S1 bit clear and the S2 bit set. 178 When the S-BFD Reflector is deactivated, the OSPF speaker advertising 179 this S-BFD Discriminator MUST originate a new Router Information LSA 180 that no longer includes the corresponding S-BFD Discriminator TLV, 181 provided there are other TLVs in the LSA. If there are no other TLVs 182 in the LSA, it MUST either send an empty Router Information LSA or 183 purge it by prematurely ageing it. 185 For intra-area reachability, the S-BFD Discriminator TLV information 186 regarding a specific target identifier is only considered current and 187 useable when the router advertising this information is itself 188 reachable via OSPF calculated paths in the same area of the LSA in 189 which the S-BFD Discriminator TLV appears. In the case of domain- 190 wide flooding, i.e., where the originator is sitting in a remote 191 area, the mechanism described in section 5 of [RFC5250] should be 192 used. 194 A change in information in the S-BFD Discriminator TLV MUST NOT 195 trigger any SPF computation at a receiving router. 197 3. Backward Compatibility 199 The S-BFD Discriminator TLV defined in this document does not 200 introduce any interoperability issues. 202 A router not supporting the S-BFD Discriminator TLV will just 203 silently ignore the TLV as specified in [RFC7770]. 205 4. Security Considerations 207 This document defines OSPF extensions to distribute the S-BFD 208 discriminator within an administrative domain. Hence the security of 209 the S-BFD discriminator distribution relies on the security of OSPF. 211 OSPF provides no encryption mechanism for protecting the privacy of 212 LSAs and, in particular, the privacy of the S-BFD discriminator 213 advertisement information. This however is not a concern as there 214 isn't any need to hide the discriminator value that can be used to 215 reach the Reflectors. 217 5. IANA Considerations 219 IANA has defined a registry for TLVs carried in the Router 220 Information LSA defined in [RFC7770]. IANA needs to assign a new TLV 221 codepoint for the S-BFD Discriminator TLV carried within the Router 222 Information LSA. 224 Value TLV Name Reference 225 ----- -------- ---------- 226 TBD S-BFD (this document) 227 Discriminator 229 6. Acknowledgements 231 The authors would like to thank Nobo Akiya, Les Ginsberg, Mach Chen 232 and Peter Psenak for insightful comments and useful suggestions. 234 7. References 236 7.1. Normative References 238 [I-D.ietf-bfd-seamless-base] 239 Akiya, N., Pignataro, C., Ward, D., Bhatia, M., and J. 240 Networks, "Seamless Bidirectional Forwarding Detection 241 (S-BFD)", draft-ietf-bfd-seamless-base-08 (work in 242 progress), February 2016. 244 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 245 Requirement Levels", BCP 14, RFC 2119, 246 DOI 10.17487/RFC2119, March 1997, 247 . 249 [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, 250 DOI 10.17487/RFC2328, April 1998, 251 . 253 [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF 254 for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, 255 . 257 [RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and 258 S. Shaffer, "Extensions to OSPF for Advertising Optional 259 Router Capabilities", RFC 7770, DOI 10.17487/RFC7770, 260 February 2016, . 262 7.2. Informative References 264 [RFC5250] Berger, L., Bryskin, I., Zinin, A., and R. Coltun, "The 265 OSPF Opaque LSA Option", RFC 5250, DOI 10.17487/RFC5250, 266 July 2008, . 268 Authors' Addresses 270 Manav Bhatia 271 Ionos Networks 273 Email: manav@ionosnetworks.com 275 Carlos Pignataro 276 Cisco Systems 278 Email: cpignata@cisco.com 279 Sam Aldrin 280 Huawei Technologies 282 Email: aldrin.ietf@gmail.com 284 Trilok Ranganath 285 Alcatel-Lucent 287 Email: trilok.ranganatha@alcatel-lucent.com