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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in RFCs) == Unused Reference: 'RFC5226' is defined on line 202, but no explicit reference was found in the text == Outdated reference: A later version (-10) exists of draft-ietf-idr-as4octet-extcomm-generic-subtype-06 ** Obsolete normative reference: RFC 5226 (Obsoleted by RFC 8126) 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 B. Decraene 3 Internet-Draft Orange 4 Intended status: Standards Track P. Francois 5 Expires: June 5, 2014 IMDEA Networks 6 December 2, 2013 8 Assigned BGP extended communities 9 draft-ietf-idr-reserved-extended-communities-06 11 Abstract 13 This document defines an IANA registry in order to assign non- 14 transitive extended communities from. These are similar to the 15 existing well-known BGP communities defined in RFC 1997 but provide a 16 control over inter-AS community advertisement as, per RFC RFC 4360, 17 they are not transitive across Autonomous System boundaries. 19 For that purpose, this document defines the use of the reserved 20 Autonomous System number 0.65535 in the non-transitive generic four- 21 octet AS specific extended community type. 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 RFC 2119 [RFC2119]. 29 Status of This Memo 31 This Internet-Draft is submitted in full conformance with the 32 provisions of BCP 78 and BCP 79. 34 Internet-Drafts are working documents of the Internet Engineering 35 Task Force (IETF). Note that other groups may also distribute 36 working documents as Internet-Drafts. The list of current Internet- 37 Drafts is at http://datatracker.ietf.org/drafts/current/. 39 Internet-Drafts are draft documents valid for a maximum of six months 40 and may be updated, replaced, or obsoleted by other documents at any 41 time. It is inappropriate to use Internet-Drafts as reference 42 material or to cite them other than as "work in progress." 44 This Internet-Draft will expire on June 5, 2014. 46 Copyright Notice 47 Copyright (c) 2013 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 1. Introduction 62 [RFC1997] defines the BGP community attribute and some BGP well-known 63 communities whose meaning SHALL be understood by all compliant 64 implementations. New communities can be registered in the IANA "BGP 65 Well-known Communities" registry but it can't be assumed anymore that 66 they will be known by all BGP implementations. Implementations or 67 BGP policies which recognize them will behave as specified in the 68 IANA registry. Implementations which do not recognize those new IANA 69 assigned communities will propagate them from BGP neighbor to BGP 70 neighbor and from AS to AS with an unlimited scope. 72 There is currently no agreed way to register a non-transitive well- 73 known community. 75 On one hand, [RFC1997] defines BGP Well-known communities with no 76 structure to set their transitiveness across ASes. Without 77 structure, communities can only be filtered by explicitly enumerating 78 all community values that will be denied or allowed to BGP speakers 79 in neighboring ASes. This is not satisfactory as this would require 80 upgrading all border routers to understand this community before its 81 first usage. 83 On the other hand, [RFC4360] defines the BGP extended community 84 attribute with a structure including a type and a transitive bit "T". 85 This transitive bit, when set, allows to restrict the scope of the 86 community within an AS. But there is no IANA registry to allocate 87 one well-known extended community. [RFC4360] defines IANA registries 88 to allocate BGP Extended Communities types. Each type is able to 89 encode 2^48 or 2^56 values depending on the type being extended or 90 regular. Therefore, one needing to reserve a single non-transitive 91 extended community would need to reserve an extended subtype which 92 represents 2^48 communities, while a single value is used. This 93 would both waste the resources and disable the ability to define 94 global policies on reserved communities, such as to accept them or to 95 filter them out. In addition, using a new community type typically 96 requires a software upgrade on both the router setting the community 97 and the router using it in a BGP policy. So this would not allow the 98 networking community to quickly define and use a new community. 100 To address this limitation, this document defines an IANA registry in 101 order to allow the registration of non-transitive extended 102 communities. These are similar to the existing Well-known BGP 103 communities defined in [RFC1997] but provides a control on inter-AS 104 community advertisement. Indeed, as per [RFC4360] non-transitive 105 communities are removed from routes propagated to another AS. 107 2. Assigned non-transitive extended communities 109 [I-D.ietf-idr-as4octet-extcomm-generic-subtype] defines a generic 110 sub-type for the four-octet AS specific extended community. The 111 value of the four-octets Global Administrator sub-field contains a 112 four-octet Autonomous System number. The value of their two-octet 113 Local Administrator sub-field has semantics defined by the Autonomous 114 System set in the Global Administrator sub-field. 116 This document updates [I-D.ietf-idr-as4octet-extcomm-generic-subtype] 117 and defines the use of the Local Administrator sub-field of the "non- 118 transitive generic four-octet AS specific" extended community type 119 when the AS number has the reserved value 0.65535 (0x0000FFFF). 121 When the AS number, encoded in the Global Administrator sub-field, 122 has the reserved value 0.65535, the communities have global 123 significance. The lists of those communities are maintained by the 124 IANA in the registry "Assigned non-transitive extended communities". 126 Note that this use of the reserved AS number 0.65535 in the AS field 127 of the communities is similar to the one defined by [RFC1997] for the 128 BGP Well-Known communities. In particular, [RFC1997] also uses the 129 reserved AS number 65535. 131 3. Assigned transitive extended communities 133 As per [RFC6793], a 2-octet Autonomous System number can be converted 134 into a 4-octet Autonomous System number by setting the two high-order 135 octets of the 4-octet field to zero. This applies to the reserved 136 2-octet Autonous System number 65535 which could use either a 137 standard community or the 4-octet AS specific generic extended 138 community. As noted in 139 [I-D.ietf-idr-as4octet-extcomm-generic-subtype], this is undesirable 140 as they would be treated as different communities, even if they had 141 the same values. 143 Therefore, this document does not define a transitive extended 144 community registry. Transitive communities are to be assigned as per 145 [RFC1997]. 147 4. IANA Considerations 149 The IANA is requested to create and maintain a registry entitled 150 "Assigned non-transitive extended communities" with the following 151 registration procedure: 153 Registry Name: Assigned non-transitive extended communities 154 with Global Significance 156 Range Registration Procedures 157 ----------- ------------------------- 158 0x0000-8000 First Come First Served 159 0x8001-FFFF Standards Action/Early IANA Allocation 161 An application may need both a transitive and a non-transitive 162 community and it may be beneficial to have the same value for both 163 communities. Therefore, the IANA SHOULD try to accommodate such 164 request to get both a non-transitive community from the above 165 "Assigned non transitive extended communities" and a transitive 166 community from [RFC1997] BGP Well-known Communities with the same 167 (lower two-octets) value for both. 169 5. Security Considerations 171 This document defines IANA actions. In itself, it has no impact on 172 the security of the BGP protocol. 174 It allows the allocation of non-transitive global communities which 175 are not propagated across Autonomous System boundaries. Compared to 176 a transitive well-known community, a non-transitive community can 177 provide some security benefit both for the sender and the receiver of 178 the community. 180 6. Acknowledgements 182 We would like to acknowledge John Scudder, Jeffrey Haas and Yakov 183 Rekhter for their contribution to this document. 185 7. Normative References 187 [I-D.ietf-idr-as4octet-extcomm-generic-subtype] 188 Rao, D., Mohapatra, P., and J. Haas, "Generic Subtype for 189 BGP Four-octet AS specific extended community", draft- 190 ietf-idr-as4octet-extcomm-generic-subtype-06 (work in 191 progress), October 2012. 193 [RFC1997] Chandrasekeran, R., Traina, P., and T. Li, "BGP 194 Communities Attribute", RFC 1997, August 1996. 196 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 197 Requirement Levels", BCP 14, RFC 2119, March 1997. 199 [RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended 200 Communities Attribute", RFC 4360, February 2006. 202 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 203 IANA Considerations Section in RFCs", BCP 26, RFC 5226, 204 May 2008. 206 [RFC6793] Vohra, Q. and E. Chen, "BGP Support for Four-Octet 207 Autonomous System (AS) Number Space", RFC 6793, December 208 2012. 210 Appendix A. Appendix A. Changes / Author Notes 212 [RFC Editor: Please remove this section before publication ] 214 Changes -01: 216 o Name changed from 'Reserved BGP extended communities' to 'Assigned 217 BGP extended communities' 219 o Addition of section 'Assigned extended communities' 221 Changes -02: no change, refresh only. 223 Changes -03: 225 o Use of AS number 0.65535 (0x0000FFFF) instead of AS 0. This is 226 better aligned with RFC 1997 which also uses AS 65535. 228 o Remove the transitive flavor of assigned extended communities. 229 RFC 1997 well-known standard communities to be used instead. 231 Changes -04: no change, refresh only. 233 Changes -05: minor editorial change (RFC 4893 obsoleted by 6793). 235 Changes -06: typo fixed, minor editorial change. 237 Authors' Addresses 239 Bruno Decraene 240 Orange 241 38 rue du General Leclerc 242 Issy Moulineaux cedex 9 92794 243 France 245 Email: bruno.decraene@orange.com 247 Pierre Francois 248 IMDEA Networks 249 Avda. del Mar Mediterraneo, 22 250 Leganese 28918 251 ES 253 Email: pierre.francois@imdea.org