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Boilerplate error? (The document does seem to have the reference to RFC 2119 which the ID-Checklist requires). -- The document date (December 1, 2016) is 2700 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references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 4893 (Obsoleted by RFC 6793) == Outdated reference: A later version (-12) exists of draft-ietf-idr-large-community-09 Summary: 1 error (**), 0 flaws (~~), 3 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group D. Rao 3 Internet-Draft Cisco Systems 4 Intended status: Standards Track P. Mohapatra 5 Expires: June 4, 2017 Sproute Networks 6 J. Haas 7 Juniper Networks, Inc. 8 December 1, 2016 10 Generic Subtype for BGP Four-octet AS specific extended community 11 draft-ietf-idr-as4octet-extcomm-generic-subtype-10 13 Abstract 15 Maintaining the current best practices with communities, ISPs and 16 enterprises that are assigned a 4-octet AS number may want the BGP 17 UPDATE messages they receive from their customers or peers to include 18 a 4-octet AS specific BGP extended community. This document defines 19 a new sub-type within the four-octet AS specific extended community 20 to facilitate this practice. 22 Requirements Language 24 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 25 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to 26 be interpreted as described in [RFC2119] only when they appear in all 27 upper case. They may also appear in lower or mixed case as English 28 words, without normative meaning. 30 Status of This Memo 32 This Internet-Draft is submitted in full conformance with the 33 provisions of BCP 78 and BCP 79. 35 Internet-Drafts are working documents of the Internet Engineering 36 Task Force (IETF). Note that other groups may also distribute 37 working documents as Internet-Drafts. The list of current Internet- 38 Drafts is at http://datatracker.ietf.org/drafts/current/. 40 Internet-Drafts are draft documents valid for a maximum of six months 41 and may be updated, replaced, or obsoleted by other documents at any 42 time. It is inappropriate to use Internet-Drafts as reference 43 material or to cite them other than as "work in progress." 45 This Internet-Draft will expire on June 4, 2017. 47 Copyright Notice 49 Copyright (c) 2016 IETF Trust and the persons identified as the 50 document authors. All rights reserved. 52 This document is subject to BCP 78 and the IETF Trust's Legal 53 Provisions Relating to IETF Documents 54 (http://trustee.ietf.org/license-info) in effect on the date of 55 publication of this document. Please review these documents 56 carefully, as they describe your rights and restrictions with respect 57 to this document. Code Components extracted from this document must 58 include Simplified BSD License text as described in Section 4.e of 59 the Trust Legal Provisions and are provided without warranty as 60 described in the Simplified BSD License. 62 Table of Contents 64 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 65 2. Generic Sub-type Definition . . . . . . . . . . . . . . . . . 3 66 3. Deployment Considerations . . . . . . . . . . . . . . . . . . 4 67 4. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 4 68 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 69 6. Security Considerations . . . . . . . . . . . . . . . . . . . 5 70 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 71 7.1. Normative References . . . . . . . . . . . . . . . . . . 5 72 7.2. Informative References . . . . . . . . . . . . . . . . . 5 73 Appendix A. Document History . . . . . . . . . . . . . . . . . . 5 74 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 76 1. Introduction 78 Maintaining the current best practices with communities, ISPs and 79 enterprises that are assigned a 4-octet AS number may want the BGP 80 UPDATE messages they receive from their customers or peers to include 81 a 4-octet AS specific extended community. This document defines a 82 new sub-type within the four-octet AS specific extended community to 83 facilitate this practice. 85 For example, [RFC1998] describes an application of BGP community 86 attribute ([RFC1997]) to implement flexible routing policies for 87 sites multi-homed to one or multiple providers. In a two-octet AS 88 environment, the advertised routes are usually associated with a 89 community attribute that encodes the provider's AS number in the 90 first two octets of the community and a LOCAL_PREF value in the 91 second two octets of the community. The community attribute signals 92 the provider edge routers connected to the site to set the 93 corresponding LOCAL_PREF on their advertisements to the IBGP mesh. 95 In this way, customers can put into practice topologies like active- 96 backup. 98 When such a provider is assigned a four-octet AS number, the existing 99 mechanism of using communities is not sufficient since the AS portion 100 of the RFC 1997 community cannot exceed two bytes. The natural 101 alternative is to extend the same mechanism using extended 102 communities since it allows for encoding eight bytes of information. 104 [RFC5668] defines a format for a four-octet AS specific extended 105 community with a designated type field. That document defines two 106 sub-types: Four-octet specific Route Target extended community and 107 Four-octet specific Route Origin extended community. This document 108 specifies a generic sub-type for the four-octet AS specific extended 109 community to provide benefits such as the one cited above as the 110 Internet migrates to four-octet AS space. 112 2. Generic Sub-type Definition 114 0 1 2 3 115 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 1 116 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 117 | 0x02 or 0x42 | 0x04 | Global | 118 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 119 | Administrator | Local Administrator | 120 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 122 This is an extended type with Type Field comprising of 2 octets and 123 Value Field comprising of 6 octets. 125 The high-order octet of this extended type is set to either 0x02 (for 126 transitive communities) or 0x42 (for non-transitive communities). 127 The low-order octet or the sub-type is set to 0x04. 129 The Value Field consists of two sub-fields: 131 Global Administrator sub-field: 4 octets 133 This sub-field contains a four-octet Autonomous System number. 135 Local Administrator sub-field: 2 octets 137 This sub-field contains a value that can influence routing 138 policies. This value has semantics that are of significance 139 for the Autonomous System in the Global Administrator field. 141 3. Deployment Considerations 143 There are situations in peering where a 4-octet AS specific generic 144 extended community cannot be used. 146 A speaker with a 4-octet AS may not support 4-octet extended 147 communities; or the speaker may have a customer or peer that does not 148 support 4-octet extended communities. In all such cases, the speaker 149 may need to define an appropriate standard community value for the 150 same purpose. As an example, a peer may tag its routes with a 151 community that encodes AS_TRANS [RFC4893] as the first two octets. 153 Similarly, as per [RFC4893], a 2-octet Autonomous System number can 154 be converted into a 4-octet Autonomous System number by setting the 155 two high-order octets of the 4-octet field to zero. As a 156 consequence, at least in principle, an Autonomous System that has a 157 2-octet AS number could use either a standard community or the 158 4-octet AS specific generic extended community. This is undesirable, 159 as they would be treated as different communities, even if they had 160 the same values. 162 Therefore, for backward compatibility with existing deployments and 163 to avoid inconsistencies between standard communities and 4-octet 164 extended communities, Autonomous Systems that use 2-octet Autonomous 165 System numbers SHOULD use standard 2-octet communities as defined in 166 RFC1997 rather than the 4-octet AS specific extended community as 167 defined in this document. 169 4. Acknowledgments 171 The authors would like to thank Paul Jakma, Bruno Decraene and Cayle 172 Spandon for their useful comments on the document. 174 5. IANA Considerations 176 Prior revisions of this document requested IANA to make assignments 177 from the Transitive Four-Octet AS Specific Extended Community Sub- 178 Type registry and the Non-Transitive Four-Octet AS Specific Extended 179 Community Sub-Type registry. The sub-type value of 0x04 in each of 180 those registries was previously assigned: 182 Name Value 183 ---- ----- 184 transitive generic four-octet AS specific 0x0204 185 non-transitive generic four-octet AS specific 0x4204 187 IANA is requested to deprecate these assignments. 189 6. Security Considerations 191 There are no additional security risks introduced by this design. 193 7. References 195 7.1. Normative References 197 [RFC1997] Chandra, R., Traina, P., and T. Li, "BGP Communities 198 Attribute", RFC 1997, DOI 10.17487/RFC1997, August 1996, 199 . 201 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 202 Requirement Levels", BCP 14, RFC 2119, 203 DOI 10.17487/RFC2119, March 1997, 204 . 206 [RFC4893] Vohra, Q. and E. Chen, "BGP Support for Four-octet AS 207 Number Space", RFC 4893, DOI 10.17487/RFC4893, May 2007, 208 . 210 [RFC5668] Rekhter, Y., Sangli, S., and D. Tappan, "4-Octet AS 211 Specific BGP Extended Community", RFC 5668, 212 DOI 10.17487/RFC5668, October 2009, 213 . 215 7.2. Informative References 217 [I-D.ietf-idr-large-community] 218 Heitz, J., Snijders, J., Patel, K., Bagdonas, I., and N. 219 Hilliard, "BGP Large Communities", draft-ietf-idr-large- 220 community-09 (work in progress), November 2016. 222 [RFC1998] Chen, E. and T. Bates, "An Application of the BGP 223 Community Attribute in Multi-home Routing", RFC 1998, 224 DOI 10.17487/RFC1998, August 1996, 225 . 227 Appendix A. Document History 229 This final version of the document exists only to request IANA to 230 deprecate its prior Extended Community assignments and provide a 231 historical record of the reason. 233 During the development of the BGP Four-octet feature [RFC4893], 234 operators had offered their commentarythat parity was needed with 235 existing BGP Community practices similar to those defined in 236 [RFC1998]. What became clear over time was that some operators 237 encoded an AS number as the second field of their community; 238 essentially, as the "target". 240 Since an Extended Community's Local Administrator field cannot encode 241 more than two octets of value, the Extended Community format was not 242 appropriate for addressing parity of existing operational practices. 243 The BGP Large Communities Feature [I-D.ietf-idr-large-community] 244 supplanted the work begun in this document. 246 Authors' Addresses 248 Dhananjaya Rao 249 Cisco Systems 250 170 W. Tasman Drive 251 San Jose, CA 95134 252 USA 254 Email: dhrao@cisco.com 256 Pradosh Mohapatra 257 Sproute Networks 259 Email: mpradosh@yahoo.com 261 Jeffrey Haas 262 Juniper Networks, Inc. 263 1133 Innovation Way 264 Sunnyvale, CA 94089 265 US 267 Email: jhaas@juniper.net