Network Working Group B. Decraene Internet-Draft France Telecom - Orange Intended status: Standards Track P. Francois Expires:August 11,November 24, 2011UCL February 07,Universite catholique de Louvain May 23, 2011ReservedAssigned BGP extended communitiesdraft-ietf-idr-reserved-extended-communities-00draft-ietf-idr-reserved-extended-communities-01 Abstract This documentassigns two BGP extended community types, one transitive and one non-transitive. It alsodefines two IANA registries in order toallow the allocation of reservedassign transitive and non-transitive extendedcommunities.communities from. These are similar to the existingreserved (formerly Well-known)well-known BGP communities defined in RFC 1997 butprovidesprovide an easier control of inter-AS community advertisement as a community could be chosen as transitive or non- transitive across ASes. For that purpose, this document defines the use of the reserved AS number 0 for the transitive and non-transitive generic four-octet AS specific extended community types. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire onAugust 11,November 24, 2011. Copyright Notice Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. 1. Introduction [RFC1997] defines the BGP community attribute and some BGPWell knownwell-known communities whose meaning SHALL be understood by all compliant implementations. Newreservedcommunities can be registered in the IANA "BGP Well-known Communities" registry but it can't be assumed anymore that they will be known by all BGP implementations. Implementations or BGP policies which recognize them will behave as specified.ImplementationImplementations which do not recognize those new reserved communities will propagate them from BGP neighbor to BGP neighbor and from AS to AS with an unlimited scope. There is currently no agreed way toreserveregister a non transitivewellwell- known community:oOn one hand, [RFC1997] defines BGP Well-known communities with no structure to set their transitiveness across ASes. Without structure,non transitivecommunities can only be filtered by explicitly enumerating all community values that will be denied or allowed to BGP speakers in neighboring ASes. This is not satisfactory as this would require upgrading all border routers to understand this community before its first usage.oOn the other hand, [RFC4360] defines the BGP extended community attribute with a structure including a type and a transitive bit "T".TheThis transitive bit, when set, allows to restrict the scope of the community within an AS. But their is no IANA registry to allocatea (single) well knownone well-known extended community.RFC 4360[RFC4360] defines IANA registries to allocate BGP Extended Communities types. Each type is able to encode 2^48 or 2^56 values depending on the type being extended or regular. Therefore, one needing to reserve a single non-transitive extended community would need to reserve an extended subtype which represents 2^48 communities, while a single value is used. This would both waste the resources and disable the ability to define global policies on reserved communities, such as to accept them or to filter them out. To address this limitation, this documentassigns two BGP extended community types, one transitive and one non-transitive. It alsodefines two IANA registries in order to allow theallocationregistration ofreservedtransitive and non-transitive extended communities. These are similar to the existing Well-known BGP communities defined inRFC 1997[RFC1997] but provides a control on inter-AS community advertisement as a community could be chosen as transitive or non-transitive across ASes. 2.IANA Considerations IANA is requested to assign, from the registry "BGP Extended Communities Type - extended, transitive type",Assigned extended communities [I-D.ietf-idr-as4octet-extcomm-generic-subtype] defines atype value TBDgeneric sub-type for"BGP Reserved transitive extended communities": Registry Name: BGP Extended Communities Type - extended, transitive Name Type Value ---- ---------- BGP Reserved transitivethe four-octet AS specific extendedcommunities TBD (e.g. 0x9000) IANA is requested to assign, fromcommunity. The value of theregistry "BGP Extended Communities Type - extended, non-transitive",four-octets Global Administrator sub-field contains atypefour-octet Autonomous System number. The valueTBDof their two-octet Local Administrator sub-field has semantics defined by the Autonomous System set in the Global Administrator sub-field. This document updates [I-D.ietf-idr-as4octet-extcomm-generic-subtype] and defines the use of the Local Administrator sub-field when the AS number encoded in the Global Administrator sub-field has the reserved value 0. When the AS number encoded in the Global Administrator sub-field has the reserved value 0, the communities have global significance. The lists of those communities are maintained by the IANA in the registries "Assigned transitive extended communities" for"BGP Reserved non-transitivethe "transitive generic four-octet AS specific" extendedcommunities": Registry Name: BGP Extended Communities Type - extended, non-transitive Name Type Value ---- ---------- BGP Reservedcommunity type and "Assigned non-transitive extendedcommunities TBD (e.g. 0xd000)communities" for the "non- transitive generic four-octet AS specific" extended community type. Note that this use of the reserved AS number 0 in the AS field of the communities is similar to theIANA: suggested valueone defined by [RFC1997] for thetwo reservedBGPExtended Communities extended type are 0x9000 and 0xd000. Otherwise, both values should be identical, except for their T - Transitive bit (bit 1 as defined in [RFC4360]).Well-Known communities. 3. IANA Considerations The IANA is requested to create and maintain a registry entitled"BGP Reserved"Assigned transitive extendedcommunities":communities" with the following registration procedure: Registry Name:BGP ReservedAssigned transitive extended communities Range Registration Procedures-------------------------------------- -------------------------0x000000000000-FFFFFFFEFFFF Reserved 0xFFFFFFFF0000-00FFFFFF80000x0000-8000 First Come First Served0x00FFFFFF8001-FFFFFFFFFFFF0x8001-FFFF Standards Action/Early IANA Allocation The IANA is requested to create and maintain a registry entitled"BGP Reserved"Assigned non-transitive extendedcommunities":communities" with the following registration procedure: Registry Name:BGP ReservedAssigned non-transitive extended communities Range Registration Procedures-------------------------------------- -------------------------0x000000000000-FFFFFFFEFFFF Reserved 0xFFFFFFFF0000-00FFFFFF80000x0000-8000 First Come First Served0x00FFFFFF8001-FFFFFFFFFFFF0x8001-FFFF Standards Action/Early IANA Allocation An application may need both a transitive and a non-transitivereserved community. Itcommunity and it may be beneficial to have the same value for both communities. (Note that both extendedcommunitycommunities will still be different as they will differ from their T bit). The IANA SHOULD try to accommodate such request tohaveget both a transitive and non- transitivereservedassigned community with the same value for both.3.4. Security Considerations This document defines IANA actions. In itself, it has no impact on the security of the BGP protocol.4.5. Normative References [I-D.ietf-idr-as4octet-extcomm-generic-subtype] Rao, D., Mohapatra, P., and J. Haas, "Generic Subtype for BGP Four-octet AS specific extended community", draft-ietf-idr-as4octet-extcomm-generic-subtype-03 (work in progress), October 2010. [RFC1997] Chandrasekeran, R., Traina, P., and T. Li, "BGP Communities Attribute", RFC 1997, August 1996. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended Communities Attribute", RFC 4360, February 2006. [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 5226, May 2008. Authors' Addresses Bruno Decraene France Telecom - Orange38-4038 rue du General Leclerc Issy Moulineaux cedex 9 92794 France Email: bruno.decraene@orange-ftgroup.com Pierre FrancoisUCLUniversite catholique de Louvain Place Ste Barbe, 2 Louvain-la-Neuve 1348 BE Email: francois@info.ucl.ac.be