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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in RFCs) == Unused Reference: 'RFC5226' is defined on line 203, but no explicit reference was found in the text == Outdated reference: A later version (-10) exists of draft-ietf-idr-as4octet-extcomm-generic-subtype-07 ** Obsolete normative reference: RFC 5226 (Obsoleted by RFC 8126)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: July 17, 2015 IMDEA Networks 6 January 13, 2015 8 Assigned BGP extended communities 9 draft-ietf-idr-reserved-extended-communities-08 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 July 17, 2015. 46 Copyright Notice 48 Copyright (c) 2015 IETF Trust and the persons identified as the 49 document authors. All rights reserved. 51 This document is subject to BCP 78 and the IETF Trust's Legal 52 Provisions Relating to IETF Documents 53 (http://trustee.ietf.org/license-info) in effect on the date of 54 publication of this document. Please review these documents 55 carefully, as they describe your rights and restrictions with respect 56 to this document. Code Components extracted from this document must 57 include Simplified BSD License text as described in Section 4.e of 58 the Trust Legal Provisions and are provided without warranty as 59 described in the Simplified BSD License. 61 1. Introduction 63 [RFC1997] defines the BGP community attribute and some BGP well-known 64 communities whose meaning SHALL be understood by all compliant 65 implementations. New communities can be registered in the IANA "BGP 66 Well-known Communities" registry but it can't be assumed anymore that 67 they will be known by all BGP implementations. Implementations or 68 BGP policies which recognize them will behave as specified in the 69 IANA registry. Implementations which do not recognize those new IANA 70 assigned communities will propagate them from BGP neighbor to BGP 71 neighbor and from AS to AS with an unlimited scope. 73 There is currently no agreed way to register a non-transitive well- 74 known community. 76 On one hand, [RFC1997] defines BGP Well-known communities with no 77 structure to set their transitiveness across ASes. Without 78 structure, communities can only be filtered by explicitly enumerating 79 all community values that will be denied or allowed to BGP speakers 80 in neighboring ASes. This is not satisfactory as this would require 81 upgrading all border routers to understand this community before its 82 first usage. 84 On the other hand, [RFC4360] defines the BGP extended community 85 attribute with a structure including a type and a transitive bit "T". 86 This transitive bit, when set, allows to restrict the scope of the 87 community within an AS. But there is no IANA registry to allocate 88 one well-known extended community. [RFC4360] defines IANA registries 89 to allocate BGP Extended Communities types. Each type is able to 90 encode 2^48 or 2^56 values depending on the type being extended or 91 regular. Therefore, one needing to reserve a single non-transitive 92 extended community would need to reserve an extended subtype which 93 represents 2^48 communities, while a single value is used. This 94 would both waste the resources and disable the ability to define 95 global policies on reserved communities, such as to accept them or to 96 filter them out. In addition, using a new community type typically 97 requires a software upgrade on both the router setting the community 98 and the router using it in a BGP policy. So this would not allow the 99 networking community to quickly define and use a new community. 101 To address this limitation, this document defines an IANA registry in 102 order to allow the registration of non-transitive extended 103 communities. These are similar to the existing Well-known BGP 104 communities defined in [RFC1997] but provides a control on inter-AS 105 community advertisement. Indeed, as per [RFC4360] non-transitive 106 communities are removed from routes propagated to another AS. 108 2. Assigned non-transitive extended communities 110 [I-D.ietf-idr-as4octet-extcomm-generic-subtype] defines a generic 111 sub-type for the four-octet AS specific extended community. The 112 value of the four-octets Global Administrator sub-field contains a 113 four-octet Autonomous System number. The value of their two-octet 114 Local Administrator sub-field has semantics defined by the Autonomous 115 System set in the Global Administrator sub-field. 117 This document updates [I-D.ietf-idr-as4octet-extcomm-generic-subtype] 118 and defines the use of the Local Administrator sub-field of the "non- 119 transitive generic four-octet AS specific" extended community type 120 when the AS number has the reserved value 0.65535 (0x0000FFFF). 122 When the AS number, encoded in the Global Administrator sub-field, 123 has the reserved value 0.65535, the communities have global 124 significance. The lists of those communities are maintained by the 125 IANA in the registry "Assigned non-transitive extended communities". 127 Note that this use of the reserved AS number 0.65535 in the AS field 128 of the communities is similar to the one defined by [RFC1997] for the 129 BGP Well-Known communities. In particular, [RFC1997] also uses the 130 reserved AS number 65535. 132 3. Assigned transitive extended communities 134 As per [RFC6793], a 2-octet Autonomous System number can be converted 135 into a 4-octet Autonomous System number by setting the two high-order 136 octets of the 4-octet field to zero. This applies to the reserved 137 2-octet Autonous System number 65535 which could use either a 138 standard community or the 4-octet AS specific generic extended 139 community. As noted in 140 [I-D.ietf-idr-as4octet-extcomm-generic-subtype], this is undesirable 141 as they would be treated as different communities, even if they had 142 the same values. 144 Therefore, this document does not define a transitive extended 145 community registry. Transitive communities are to be assigned as per 146 [RFC1997]. 148 4. IANA Considerations 150 The IANA is requested to create and maintain a registry entitled 151 "Assigned non-transitive extended communities" with the following 152 registration procedure: 154 Registry Name: Assigned non-transitive extended communities 155 with Global Significance 157 Range Registration Procedures 158 ----------- ------------------------- 159 0x0000-8000 First Come First Served 160 0x8001-FFFF Standards Action/Early IANA Allocation 162 An application may need both a transitive and a non-transitive 163 community and it may be beneficial to have the same value for both 164 communities. Therefore, the IANA SHOULD try to accommodate such 165 request to get both a non-transitive community from the above 166 "Assigned non transitive extended communities" and a transitive 167 community from [RFC1997] BGP Well-known Communities with the same 168 (lower two-octets) value for both. 170 5. Security Considerations 172 This document defines IANA actions. In itself, it has no impact on 173 the security of the BGP protocol. 175 It allows the allocation of non-transitive global communities which 176 are not propagated across Autonomous System boundaries. Compared to 177 a transitive well-known community, a non-transitive community can 178 provide some security benefit both for the sender and the receiver of 179 the community. 181 6. Acknowledgements 183 We would like to acknowledge John Scudder, Jeffrey Haas and Yakov 184 Rekhter for their contribution to this document. 186 7. Normative References 188 [I-D.ietf-idr-as4octet-extcomm-generic-subtype] 189 Rao, D., Mohapatra, P., and J. Haas, "Generic Subtype for 190 BGP Four-octet AS specific extended community", draft- 191 ietf-idr-as4octet-extcomm-generic-subtype-07 (work in 192 progress), July 2014. 194 [RFC1997] Chandrasekeran, R., Traina, P., and T. Li, "BGP 195 Communities Attribute", RFC 1997, August 1996. 197 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 198 Requirement Levels", BCP 14, RFC 2119, March 1997. 200 [RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended 201 Communities Attribute", RFC 4360, February 2006. 203 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 204 IANA Considerations Section in RFCs", BCP 26, RFC 5226, 205 May 2008. 207 [RFC6793] Vohra, Q. and E. Chen, "BGP Support for Four-Octet 208 Autonomous System (AS) Number Space", RFC 6793, December 209 2012. 211 Appendix A. Appendix A. Changes / Author Notes 213 [RFC Editor: Please remove this section before publication ] 215 Changes -01: 217 o Name changed from 'Reserved BGP extended communities' to 'Assigned 218 BGP extended communities' 220 o Addition of section 'Assigned extended communities' 222 Changes -02: no change, refresh only. 224 Changes -03: 226 o Use of AS number 0.65535 (0x0000FFFF) instead of AS 0. This is 227 better aligned with RFC 1997 which also uses AS 65535. 229 o Remove the transitive flavor of assigned extended communities. 230 RFC 1997 well-known standard communities to be used instead. 232 Changes -04: no change, refresh only. 234 Changes -05: minor editorial change (RFC 4893 obsoleted by 6793). 236 Changes -06: typo fixed, minor editorial change. 238 Changes -07, 08: no change, refresh only. 240 Authors' Addresses 242 Bruno Decraene 243 Orange 244 38 rue du General Leclerc 245 Issy Moulineaux cedex 9 92794 246 France 248 Email: bruno.decraene@orange.com 250 Pierre Francois 251 IMDEA Networks 252 Avda. del Mar Mediterraneo, 22 253 Leganese 28918 254 ES 256 Email: pierre.francois@imdea.org