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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group K. Patel 3 Internet-Draft R. Fernando 4 Intended status: Standards Track Cisco Systems 5 Expires: August 5, 2011 J. Scudder 6 J. Haas 7 Juniper Networks 8 February 2011 10 Graceful Restart Extensions for BGP 11 draft-keyupate-idr-bgp-gr-extension-00.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 August 5, 2011. 41 Copyright Notice 43 Copyright (c) 2011 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 . . . . . . . . . . . . . . . . . . . . . . . . . 4 71 1.1. Requirements Language . . . . . . . . . . . . . . . . . . . 4 72 2. Modifications to BGP Graceful Restart Capability . . . . . . . 4 73 3. BGP Hard Reset Subcode . . . . . . . . . . . . . . . . . . . . 5 74 4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 75 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6 76 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 77 7. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 78 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 79 8.1. Normative References . . . . . . . . . . . . . . . . . . . 7 80 8.2. Informative References . . . . . . . . . . . . . . . . . . 7 81 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 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 flags field for Address Family is augmented as 111 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 Flags for Address Family: 135 This field contains bit flags relating to routes that were 136 advertised with the given AFI and SAFI. 138 0 1 2 3 4 5 6 7 139 +-+-+-+-+-+-+-+-+ 140 |F|N| Reserved | 141 +-+-+-+-+-+-+-+-+ 143 The second most significant bit "N" is defined as a BGP Graceful 144 Notification bit, which is used to indicate the Graceful Restart 145 support for BGP NOTIFICATION messages. BGP speaker indicates the 146 Graceful Restart support for BGP NOTIFICATION messages and its 147 ability to handle the new BGP NOTIFICATION Cease message subcode and 148 the format for a BGP NOTIFICATION Cease message defined in [RFC4486] 149 when the Graceful NOTIFICATION bit is set (value 1). 151 3. BGP Hard Reset Subcode 153 A new BGP Cease message subcode is defined known as BGP Hard Reset 154 Subcode. The value of this subcode is 9. 156 Whenever a BGP speaker receives a NOTIFICATION message with the Cease 157 Error code and Hard Reset Error subcode, the speaker MUST terminate 158 the BGP session following the standard procedures in [RFC4271]. 160 4. Operation 162 A BGP speaker that is willing to receive and send BGP NOTIFICATION 163 messages in Graceful mode should advertise the BGP Graceful 164 Notification Flag "N" using the Graceful Restart Capability as 165 defined in [RFC4724]. 167 When a BGP Speaker receives a BGP NOTIFICATION message, it SHOULD 168 follow the standard rules of the receiving speaker mentioned in 169 [RFC4724] for all AFI/SAFIs for which it has announced the BGP 170 Graceful Notification flag. The BGP speaker generating a BGP 171 NOTIFICATION message SHOULD follow the standard rules of the 172 receiving Speaker in [RFC4724] for all AFI/SAFIs that were announced 173 with the BGP Graceful Notification flag. 175 Once the session is re-established, both BGP speakers MUST set their 176 "Forwarding State" bit to 1 if they want to apply planned graceful 177 restart. The handling of the "Forwarding State" bit should be done 178 as specified by the procedures of the Receiving speaker in [RFC4724] 179 are applied. 181 As part of this extension, possible consecutive restarts SHOULD NOT 182 delete a route (from the peer) previously marked as stale, until 183 required by rules mentioned in [RFC4724]. 185 5. Acknowledgements 187 The authors would like to thank Robert Raszuk for the review and 188 comments. 190 6. IANA Considerations 192 This document defines a new BGP Cease message subcode known as BGP 193 Hard Reset Subcode. IANA mantains the list of existing BGP Cease 194 message subcodes. This document proposes defining a new BGP Cease 195 message subcode known as BGP Hard Reset Subcode with the value 9. 197 7. Security Considerations 199 This extension to BGP does not change the underlying security issues 200 inherent in the existing [RFC4724] and [RFC4271] 202 8. References 204 8.1. Normative References 206 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 207 Requirement Levels", BCP 14, RFC 2119, March 1997. 209 [RFC2842] Chandra, R. and J. Scudder, "Capabilities Advertisement 210 with BGP-4", RFC 2842, May 2000. 212 [RFC3392] Chandra, R. and J. Scudder, "Capabilities Advertisement 213 with BGP-4", RFC 3392, November 2002. 215 [RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway 216 Protocol 4 (BGP-4)", RFC 4271, January 2006. 218 [RFC4486] Chen, E. and V. Gillet, "Subcodes for BGP Cease 219 Notification Message", RFC 4486, April 2006. 221 [RFC4724] Sangli, S., Chen, E., Fernando, R., Scudder, J., and Y. 222 Rekhter, "Graceful Restart Mechanism for BGP", RFC 4724, 223 January 2007. 225 8.2. Informative References 227 [RFC2858] Bates, T., Rekhter, Y., Chandra, R., and D. Katz, 228 "Multiprotocol Extensions for BGP-4", RFC 2858, June 2000. 230 Authors' Addresses 232 Keyur Patel 233 Cisco Systems 234 170 W. Tasman Drive 235 San Jose, CA 95134 236 USA 238 Email: keyupate@cisco.com 240 Rex Fernando 241 Cisco Systems 242 170 W. Tasman Drive 243 San Jose, CA 95134 244 USA 246 Email: rex@cisco.com 247 John Scudder 248 Juniper Networks 249 1194 N. Mathilda Ave 250 Sunnyvale, CA 94089 251 USA 253 Email: jgs@juniper.net 255 Jeff Haas 256 Juniper Networks 257 1194 N. Mathilda Ave 258 Sunnyvale, CA 94089 259 USA 261 Email: jhaas@juniper.net