Network Working Group J. Mitchell Internet-Draft Microsoft Corporation Updates: 1930 (if approved) December 20, 2012 Intended status: Informational Expires: June 23, 2013 Autonomous System (AS) Reservation for Private Use draft-ietf-idr-as-private-reservation-01 Abstract This document describes the reservation of Autonomous System numbers (ASNs) that are for Private Use only and should not be advertised to the Internet, known as Private Use ASNs. This document enlarges the total space available for Private Use ASNs by documenting the reservation of a second, larger range and updates RFC 1930 by replacing Section 10. 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/. 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Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of Mitchell Expires June 23, 2013 [Page 1] Internet-Draft Private Use AS Reservation December 2012 the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. 1. Introduction The original IANA reservation of Autonomous System Numbers (ASNs) for Private Use was a block of 1023 ASNs. This was also documented by IETF in Section 10 of [RFC1930]. Since the time when that range was reserved, BGP has seen much wider deployment in service provider, enterprise, and datacenter networks. The places in these networks where Private Use ASNs are in use include networks that are attached to the Internet, utilizing implementation specific features to remove them upon advertisement to Internet peers, and networks that are not attached to the Internet. The limited size of the current range of Private Use ASNs has led to the re-use of the same ASN within a single organization, requiring the use of a number of implementation specific features that manipulate the AS_PATH or remove AS_PATH based loop prevention described in Section 9 of [RFC4271]. These workarounds have increased the operational complexity of the networks since the implementations of these functions vary and are not defined in existing BGP standards. Since the introduction of BGP Support for Four-octet AS Number Space [RFC6793], the total size of the ASN space has increased dramatically, and a larger subset of the space should be available to network operators to deploy in Private Use cases. The existing range of Private Use ASNs is widely deployed and the ability to renumber this resource in existing networks cannot be coordinated given these ASNs by definition are not registered. Therefore this documents the existing Private Use ASN reservation, while also introducing a second, larger range that can also be utilized. 2. Private Use ASNs To allow the continued growth of usage of the BGP protocol in networks that utilize Private Use ASNs, two ranges of ASNs are reserved by this document in Section 5. The first which was previously defined in [RFC1930] out of the original 16-bit Autonomous System range and a second, larger range out of the higher part of the Four-Octet AS Number Space [RFC6793]. Mitchell Expires June 23, 2013 [Page 2] Internet-Draft Private Use AS Reservation December 2012 3. Operational Considerations If Private Use ASNs are used and prefixes are originated from these ASNs which are destined to the Internet, Private Use ASNs must be removed from the AS_PATH before being advertised to the global Internet. Operators are cautioned to ensure any implementation specific features that recognize Private Use ASNs have been updated to recognize both ranges prior to making use of the newer, numerically higher range of Private Use ASNs. Some implementations of such features will fail to remove any Private Use ASNs from the AS_PATH if the AS_PATH contains a mix of Private Use and non-Private Use ASNs and if these implementations are not updated, the newer range may be classified as the later. Normal AS_PATH filtering may also be used to limit prefixes originating from Private Use ASNs from being advertised to the global Internet and can help in transition scenarios until the implementation specific features that manipulate AS_PATH are updated. 4. Acknowledgements The author would like to acknowledge Christopher Morrow, Jason Schiller, and John Scudder for their advice on how to pursue this change. The author would also like to thank Brian Dickson, David Farmer, Jeffrey Haas, Nick Hilliard, Warren Kumari, and Jeff Wheeler for their comments and suggestions. 5. IANA Considerations [Note to IANA, NOT for publication: The IANA should update the "16- bit Autonomous System Numbers" registry to reference this RFC (when published) for the existing Private Use reservation. Further, to maintain consistency from an operator standpoint, it is suggested that the end of the "32-bit Autonomous System Numbers" range be reserved for Private Use, and a size of 94,967,295 (value to replace TBD1 below) is suggested corresponding to the range of 4200000000 (value to replace TBD2 below) to 4294967294 (value to replace TBD3 below).] IANA has reserved, for Private Use, a contiguous block of 1023 Autonomous System numbers from the "16-bit Autonomous System Numbers" registry, namely 64512 - 65534 inclusive. IANA has also reserved, for Private Use, a contiguous block of TBD1 Autonomous System numbers from the "32-bit Autonomous System Numbers" registry, namely TBD2 - TBD3 inclusive. Mitchell Expires June 23, 2013 [Page 3] Internet-Draft Private Use AS Reservation December 2012 These reservations have been documented in the IANA Autonomous System Numbers Registry [IANA.AS]. 6. Security Considerations This document does not introduce any additional security concerns in regards to Private Use ASNs. 7. References 7.1. Normative References [RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway Protocol 4 (BGP-4)", RFC 4271, January 2006. [RFC6793] Vohra, Q. and E. Chen, "BGP Support for Four-Octet Autonomous System (AS) Number Space", RFC 6793, December 2012. 7.2. Informative References [IANA.AS] IANA, "Autonomous System (AS) Numbers", December 2012, . [RFC1930] Hawkinson, J. and T. Bates, "Guidelines for creation, selection, and registration of an Autonomous System (AS)", BCP 6, RFC 1930, March 1996. Author's Address Jon Mitchell Microsoft Corporation 12012 Sunset Hills Road Reston, VA 20190 USA Email: Jon.Mitchell@microsoft.com Mitchell Expires June 23, 2013 [Page 4]