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(The document does seem to have the reference to RFC 2119 which the ID-Checklist requires). -- The document date (24 February 2022) is 79 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) == Unused Reference: 'RFC4486' is defined on line 185, but no explicit reference was found in the text Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Inter-Domain Routing J. Haas 3 Internet-Draft Juniper Networks 4 Intended status: Standards Track 24 February 2022 5 Expires: 28 August 2022 7 BGP Cease Notification Subcode For BFD 8 draft-ietf-idr-bfd-subcode-02 10 Abstract 12 The Bidirectional Forwarding Detection protocol (BFD) is used to 13 detect loss of connectivity between two forwarding engines, typically 14 with low latency. BFD is leveraged by routing protocols, including 15 the Border Gateway Protocol (BGP), to use that detection of loss of 16 connectivity to bring down the protocol connections faster than the 17 native protocol timers. 19 This document defines a Subcode for the BGP Cease NOTIFICATION 20 message for when a BGP connection is being closed due to a BFD 21 session going down. 23 Requirements Language 25 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 26 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 27 document are to be interpreted as described in BCP 14 [RFC2119] 28 [RFC8174] when, and only when, they appear in all capitals, as shown 29 here. 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 28 August 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 (https://trustee.ietf.org/ 55 license-info) in effect on the date of publication of this document. 56 Please review these documents carefully, as they describe your rights 57 and restrictions with respect to this document. Code Components 58 extracted from this document must include Revised BSD License text as 59 described in Section 4.e of the Trust Legal Provisions and are 60 provided without warranty as described in the Revised BSD License. 62 Table of Contents 64 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 65 2. BFD Cease NOTIFICATION Subcode . . . . . . . . . . . . . . . 3 66 3. Operational Considerations . . . . . . . . . . . . . . . . . 3 67 4. Security Considerations . . . . . . . . . . . . . . . . . . . 3 68 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 69 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 4 70 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 71 7.1. Normative References . . . . . . . . . . . . . . . . . . 4 72 7.2. Informative References . . . . . . . . . . . . . . . . . 4 73 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5 75 1. Introduction 77 The Bidirectional Forwarding Detection protocol (BFD) [RFC5880] is 78 used to detect loss of connectivity between two forwarding engines, 79 typically with low latency. BFD is utilized as a service for various 80 clients, including routing protocols, to provide an advisory 81 mechanism for those clients to take action when a BFD session goes 82 down [RFC5882]. This is typically used by the clients to take faster 83 action in terminating their connections than the native protocol 84 timers might allow. 86 The Border Gateway Protocol, Version 4 (BGP) [RFC4271] terminates its 87 sessions upon Hold Timer expiration when the speaker does not receive 88 a BGP message within the negotiated Hold Time interval. The minimum 89 Hold Time interval supported by the protocol is three seconds. The 90 Hold Timer may be optionally negotiated to being disabled with a Hold 91 Time interval of zero. 93 If a BGP speaker desires to have its sessions terminate faster than 94 the supported BGP Hold Timer can accommodate upon loss of 95 connectivity, BFD is used to supply that faster detection. When the 96 BFD session state changes to Down, the BGP speaker terminates the 97 session. BGP will send a NOTIFICATION message, if possible, and then 98 close the TCP connection for the session. 100 2. BFD Cease NOTIFICATION Subcode 102 The value 10 has been allocated by IANA for the "BFD Down" Cease 103 NOTIFICATION message Subcode. 105 When a BGP session is terminated due to a BFD session going into the 106 Down state, the BGP Speaker SHOULD send a NOTIFICATION message with 107 the Error Code Cease and the Error Subcode "BFD Down". 109 3. Operational Considerations 111 A BFD session may go Down when there is only a partial loss of 112 connectivity between two BGP Speakers. Operators using BFD for their 113 BGP sessions make choices for what BFD timers are used based on a 114 variety of inputs for stability vs. fast failure depending on the 115 role BGP is playing for the deployment. 117 In the event of a BGP session being terminated due to a BFD Down 118 event from partial loss of connectivity as detected by BFD, the 119 remote BGP Speaker might be able to receive the BGP NOTIFICATION 120 message with the BFD Down Subcode. The receiving BGP Speaker will 121 then have an understanding that the session is being terminated 122 because of a BFD-detected issue and not an issue with the BGP 123 speaker. 125 When there is a total loss of connectivity between two BGP Speakers, 126 it may not be possible for the NOTIFICATION message to have been 127 sent. Even so, BGP speakers SHOULD provide this reason as part of 128 their operational state; e.g. bgpPeerLastError in the BGP MIB. 129 [RFC4273]. 131 When the procedures in [RFC8538] for sending a NOTIFICATION message 132 with a Cease Code and Hard Reset Subcode, and the session is being 133 terminated because BFD has gone Down, the BFD Down Subcode SHOULD be 134 encapsulated in the Hard Reset's data portion of the NOTIFICATION 135 message. 137 4. Security Considerations 139 This document introduces no additional BGP security considerations. 141 5. IANA Considerations 143 IANA has assigned the value 10 from the BGP Cease NOTIFICATION 144 message subcodes registry with the Name "BFD Down", and a Reference 145 of this document. 147 6. Acknowledgments 149 Thanks to Jeff Tantsura, and Dale Carder for their comments on the 150 draft. 152 Bruno Rijsman had a substantively similar proposal to this document 153 in 2006; draft-rijsman-bfd-down-subcode. That draft did not progress 154 in IDR at that time. The author of this draft was unaware of Bruno's 155 prior work when creating this proposal. 157 7. References 159 7.1. Normative References 161 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 162 Requirement Levels", BCP 14, RFC 2119, 163 DOI 10.17487/RFC2119, March 1997, 164 . 166 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 167 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 168 DOI 10.17487/RFC4271, January 2006, 169 . 171 [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection 172 (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010, 173 . 175 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 176 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 177 May 2017, . 179 7.2. Informative References 181 [RFC4273] Haas, J., Ed. and S. Hares, Ed., "Definitions of Managed 182 Objects for BGP-4", RFC 4273, DOI 10.17487/RFC4273, 183 January 2006, . 185 [RFC4486] Chen, E. and V. Gillet, "Subcodes for BGP Cease 186 Notification Message", RFC 4486, DOI 10.17487/RFC4486, 187 April 2006, . 189 [RFC5882] Katz, D. and D. Ward, "Generic Application of 190 Bidirectional Forwarding Detection (BFD)", RFC 5882, 191 DOI 10.17487/RFC5882, June 2010, 192 . 194 [RFC8538] Patel, K., Fernando, R., Scudder, J., and J. Haas, 195 "Notification Message Support for BGP Graceful Restart", 196 RFC 8538, DOI 10.17487/RFC8538, March 2019, 197 . 199 Author's Address 201 Jeffrey Haas 202 Juniper Networks 203 Email: jhaas@juniper.net