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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group K.P. Patel 3 Internet-Draft R.F. Fernando 4 Intended status: Standards Track Cisco Systems 5 Expires: October 27, 2013 J.S. Scudder 6 J.H. Haas 7 Juniper Networks 8 April 25, 2013 10 Notification Message support for BGP Graceful Restart 11 draft-ietf-idr-bgp-gr-notification-01.txt 13 Abstract 15 The current BGP Graceful Restart mechanism limits the usage of BGP 16 Graceful Restart to BGP protocol messages other than a BGP 17 NOTIFICATION message. This document defines an extension to the BGP 18 Graceful Restart that permits the Graceful Restart procedures to be 19 performed when the BGP speaker receives a BGP NOTIFICATION Message. 20 This document also defines a new BGP NOTIFICATION Cease Error subcode 21 to prevent BGP speakers supporting the extension defined in this 22 document from performing a Graceful Restart. 24 Status of This Memo 26 This Internet-Draft is submitted in full conformance with the 27 provisions of BCP 78 and BCP 79. 29 Internet-Drafts are working documents of the Internet Engineering 30 Task Force (IETF). Note that other groups may also distribute 31 working documents as Internet-Drafts. The list of current Internet- 32 Drafts is at http://datatracker.ietf.org/drafts/current/. 34 Internet-Drafts are draft documents valid for a maximum of six months 35 and may be updated, replaced, or obsoleted by other documents at any 36 time. It is inappropriate to use Internet-Drafts as reference 37 material or to cite them other than as "work in progress." 39 This Internet-Draft will expire on October 27, 2013. 41 Copyright Notice 43 Copyright (c) 2013 IETF Trust and the persons identified as the 44 document authors. All rights reserved. 46 This document is subject to BCP 78 and the IETF Trust's Legal 47 Provisions Relating to IETF Documents 48 (http://trustee.ietf.org/license-info) in effect on the date of 49 publication of this document. Please review these documents 50 carefully, as they describe your rights and restrictions with respect 51 to this document. Code Components extracted from this document must 52 include Simplified BSD License text as described in Section 4.e of 53 the Trust Legal Provisions and are provided without warranty as 54 described in the Simplified BSD License. 56 This document may contain material from IETF Documents or IETF 57 Contributions published or made publicly available before November 58 10, 2008. The person(s) controlling the copyright in some of this 59 material may not have granted the IETF Trust the right to allow 60 modifications of such material outside the IETF Standards Process. 61 Without obtaining an adequate license from the person(s) controlling 62 the copyright in such materials, this document may not be modified 63 outside the IETF Standards Process, and derivative works of it may 64 not be created outside the IETF Standards Process, except to format 65 it for publication as an RFC or to translate it into languages other 66 than English. 68 Table of Contents 70 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 71 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 72 2. Modifications to BGP Graceful Restart Capability . . . . . . 3 73 3. BGP Hard Reset Subcode . . . . . . . . . . . . . . . . . . . 4 74 4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 4 75 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 76 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 77 7. Security Considerations . . . . . . . . . . . . . . . . . . . 5 78 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 79 8.1. Normative References . . . . . . . . . . . . . . . . . . 6 80 8.2. Informative References . . . . . . . . . . . . . . . . . 6 81 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 83 1. Introduction 85 For many classes of errors, the BGP protocol must send a NOTIFICATION 86 message and reset the peering session to handle the error condition. 87 The BGP Graceful Restart extension defined in [RFC4724] requires that 88 normal BGP procedures defined in [RFC4271] be followed when a 89 NOTIFICATION message is sent or received. This document defines an 90 extension to BGP Graceful Restart that permits the Graceful Restart 91 procedures to be performed when the BGP speaker receives a 92 NOTIFICATION message. This permits the BGP speaker to avoid flapping 93 reachability and continue forwarding while the BGP speaker restarts 94 the session to handle errors detected in the BGP protocol. 96 This document defines a BGP NOTIFICATION cease Error subcode for the 97 Cease Error code to prevent BGP speakers supporting the extension 98 defined in this document from performing a Graceful Restart. 100 1.1. Requirements Language 102 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 103 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 104 document are to be interpreted as described in RFC 2119 [RFC2119]. 106 2. Modifications to BGP Graceful Restart Capability 108 The BGP Graceful Restart Capability is augmented to signal the 109 Graceful Restart support for BGP NOTIFICATION messages. In 110 particular, the Restart flags field and the Flags field for Address 111 Family are augmented as follows: 113 +--------------------------------------------------+ 114 | Restart Flags (4 bits) | 115 +--------------------------------------------------+ 116 | Restart Time in seconds (12 bits) | 117 +--------------------------------------------------+ 118 | Address Family Identifier (16 bits) | 119 +--------------------------------------------------+ 120 | Subsequent Address Family Identifier (8 bits) | 121 +--------------------------------------------------+ 122 | Flags for Address Family (8 bits) | 123 +--------------------------------------------------+ 124 | ... | 125 +--------------------------------------------------+ 126 | Address Family Identifier (16 bits) | 127 +--------------------------------------------------+ 128 | Subsequent Address Family Identifier (8 bits) | 129 +--------------------------------------------------+ 130 | Flags for Address Family (8 bits) | 131 +--------------------------------------------------+ 133 Restart Flags: 135 This field contains bit flags relating to restart. 137 0 1 2 3 138 +-+-+-+-+ 139 |R|N| | 140 +-+-+-+-+ 142 The second most significant bit "N" is defined as a BGP Graceful 143 Notification bit, which is used to indicate the Graceful Restart 144 support for BGP NOTIFICATION messages. BGP speaker indicates the 145 Graceful Restart support for BGP NOTIFICATION messages and its 146 ability to handle the new BGP NOTIFICATION Cease message subcode and 147 the format for a BGP NOTIFICATION Cease message defined in [RFC4486] 148 when the Graceful NOTIFICATION bit is set (value 1). 150 Flags for Address Family: 152 This field contains bit flags relating to routes that were 153 advertised with the given AFI and SAFI. 155 0 1 2 3 4 5 6 7 156 +-+-+-+-+-+-+-+-+ 157 |F|N| Reserved | 158 +-+-+-+-+-+-+-+-+ 160 The usage of second most significant bit "N" is deprecated. This bit 161 SHOULD be reserved and set to 0. 163 3. BGP Hard Reset Subcode 165 A new BGP Cease message subcode is defined known as BGP Hard Reset 166 Subcode. The value of this subcode is 9. 168 Whenever a BGP speaker receives a NOTIFICATION message with the Cease 169 Error code and Hard Reset Error subcode, the speaker MUST terminate 170 the BGP session following the standard procedures in [RFC4271]. 172 4. Operation 174 A BGP speaker that is willing to receive and send BGP NOTIFICATION 175 messages in Graceful mode SHOULD advertise the BGP Graceful 176 Notification Flag "N" using the Graceful Restart Capability as 177 defined in [RFC4724]. 179 When a BGP Speaker receives a BGP NOTIFICATION message, it SHOULD 180 follow the standard rules of the receiving speaker mentioned in 181 [RFC4724] for all AFI/SAFIs for which it has announced the BGP 182 Graceful Notification flag. The BGP speaker generating a BGP 183 NOTIFICATION message SHOULD follow the standard rules of the 184 receiving Speaker in [RFC4724] for all AFI/SAFIs that were announced 185 with the BGP Graceful Notification flag. 187 A BGP speaker MAY continue to operate in the Graceful Restart mode 188 even if it receives a Graceful Restart capability without a Graceful 189 Notification Flag. 191 When a BGP speaker resets its session due to a HOLDTIME expiry, it 192 SHOULD follow the standard rules of the receiving speaker mentioned 193 in [RFC4724] aside from generating a BGP NOTIFICATION message as 194 mentioned in [RFC4271]. 196 Once the session is re-established, both BGP speakers MUST set their 197 "Forwarding State" bit to 1 if they want to apply planned graceful 198 restart. The handling of the "Forwarding State" bit should be done 199 as specified by the procedures of the Receiving speaker in [RFC4724] 200 are applied. 202 As part of this extension, any possible consecutive restarts SHOULD 203 NOT delete a route (from the peer) previously marked as stale, until 204 required by rules mentioned in [RFC4724]. 206 5. Acknowledgements 208 The authors would like to thank Robert Raszuk for the review and 209 comments. 211 6. IANA Considerations 213 This document defines a new BGP Cease message subcode known as BGP 214 Hard Reset Subcode. IANA mantains the list of existing BGP Cease 215 message subcodes. This document proposes defining a new BGP Cease 216 message subcode known as BGP Hard Reset Subcode with the value 9. 218 7. Security Considerations 220 This extension to BGP does not change the underlying security issues 221 inherent in the existing [RFC4724] and [RFC4271] 223 8. References 224 8.1. Normative References 226 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 227 Requirement Levels", BCP 14, RFC 2119, March 1997. 229 [RFC2842] Chandra, R. and J. Scudder, "Capabilities Advertisement 230 with BGP-4", RFC 2842, May 2000. 232 [RFC3392] Chandra, R. and J. Scudder, "Capabilities Advertisement 233 with BGP-4", RFC 3392, November 2002. 235 [RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway 236 Protocol 4 (BGP-4)", RFC 4271, January 2006. 238 [RFC4486] Chen, E. and V. Gillet, "Subcodes for BGP Cease 239 Notification Message", RFC 4486, April 2006. 241 [RFC4724] Sangli, S., Chen, E., Fernando, R., Scudder, J., and Y. 242 Rekhter, "Graceful Restart Mechanism for BGP", RFC 4724, 243 January 2007. 245 8.2. Informative References 247 [RFC2858] Bates, T., Rekhter, Y., Chandra, R., and D. Katz, 248 "Multiprotocol Extensions for BGP-4", RFC 2858, June 2000. 250 Authors' Addresses 252 Keyur Patel 253 Cisco Systems 254 170 W. Tasman Drive 255 San Jose, CA 95134 256 USA 258 Email: keyupate@cisco.com 260 Rex Fernando 261 Cisco Systems 262 170 W. Tasman Drive 263 San Jose, CA 95134 264 USA 266 Email: rex@cisco.com 267 John Scudder 268 Juniper Networks 269 1194 N. Mathilda Ave 270 Sunnyvale, CA 94089 271 USA 273 Email: jgs@juniper.net 275 Jeff Haas 276 Juniper Networks 277 1194 N. Mathilda Ave 278 Sunnyvale, CA 94089 279 USA 281 Email: jhaas@juniper.net