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Checking references for intended status: Best Current Practice ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) No issues found here. Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group J. Mitchell 3 Internet-Draft Microsoft Corporation 4 Updates: 1930 (if approved) December 21, 2012 5 Intended status: BCP 6 Expires: June 24, 2013 8 Autonomous System (AS) Reservation for Private Use 9 draft-ietf-idr-as-private-reservation-02 11 Abstract 13 This document describes the reservation of Autonomous System numbers 14 (ASNs) that are for Private Use only and MUST NOT be advertised to 15 the Internet, known as Private Use ASNs. This document enlarges the 16 total space available for Private Use ASNs by documenting the 17 reservation of a second, larger range and updates RFC 1930 by 18 replacing Section 10. 20 Status of this Memo 22 This Internet-Draft is submitted in full conformance with the 23 provisions of BCP 78 and BCP 79. 25 Internet-Drafts are working documents of the Internet Engineering 26 Task Force (IETF). Note that other groups may also distribute 27 working documents as Internet-Drafts. The list of current Internet- 28 Drafts is at http://datatracker.ietf.org/drafts/current/. 30 Internet-Drafts are draft documents valid for a maximum of six months 31 and may be updated, replaced, or obsoleted by other documents at any 32 time. It is inappropriate to use Internet-Drafts as reference 33 material or to cite them other than as "work in progress." 35 This Internet-Draft will expire on June 24, 2013. 37 Copyright Notice 39 Copyright (c) 2012 IETF Trust and the persons identified as the 40 document authors. All rights reserved. 42 This document is subject to BCP 78 and the IETF Trust's Legal 43 Provisions Relating to IETF Documents 44 (http://trustee.ietf.org/license-info) in effect on the date of 45 publication of this document. Please review these documents 46 carefully, as they describe your rights and restrictions with respect 47 to this document. Code Components extracted from this document must 48 include Simplified BSD License text as described in Section 4.e of 49 the Trust Legal Provisions and are provided without warranty as 50 described in the Simplified BSD License. 52 1. Introduction 54 The original IANA reservation of Autonomous System Numbers (ASNs) for 55 Private Use was a block of 1023 ASNs. This was also documented by 56 IETF in Section 10 of [RFC1930]. Since the time when that range was 57 reserved, BGP has seen much wider deployment in service provider, 58 enterprise, and datacenter networks. The places in these networks 59 where Private Use ASNs are in use include networks that are attached 60 to the Internet, utilizing implementation specific features to remove 61 them upon advertisement to Internet peers, and networks that are not 62 attached to the Internet. 64 The limited size of the current range of Private Use ASNs has led to 65 the re-use of the same ASN within a single organization, requiring 66 the use of a number of implementation specific features that 67 manipulate the AS_PATH or remove AS_PATH based loop prevention 68 described in Section 9 of [RFC4271]. These workarounds have 69 increased the operational complexity of the networks since the 70 implementations of these functions vary and are not defined in 71 existing BGP standards. 73 Since the introduction of BGP Support for Four-octet AS Number Space 74 [RFC6793], the total size of the ASN space has increased 75 dramatically, and a larger subset of the space should be available to 76 network operators to deploy in Private Use cases. The existing range 77 of Private Use ASNs is widely deployed and the ability to renumber 78 this resource in existing networks cannot be coordinated given these 79 ASNs by definition are not registered. Therefore this documents the 80 existing Private Use ASN reservation, while also introducing a 81 second, larger range that can also be utilized. 83 2. Requirements Language 85 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 86 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 87 document are to be interpreted as described in RFC 2119 [RFC2119]. 89 3. Private Use ASNs 91 To allow the continued growth of usage of the BGP protocol in 92 networks that utilize Private Use ASNs, two ranges of ASNs are 93 reserved by this document in Section 6. The first which was 94 previously defined in [RFC1930] out of the original 16-bit Autonomous 95 System range and a second, larger range out of the higher part of the 96 Four-Octet AS Number Space [RFC6793]. 98 4. Operational Considerations 100 If Private Use ASNs are used and prefixes are originated from these 101 ASNs which are destined to the Internet, Private Use ASNs MUST be 102 removed from the AS_PATH before being advertised to the global 103 Internet. Operators are cautioned to ensure any implementation 104 specific features that recognize Private Use ASNs have been updated 105 to recognize both ranges prior to making use of the newer, 106 numerically higher range of Private Use ASNs. Some existing 107 implementations that remove Private Use ASNs from the AS_PATH may 108 fail to remove Private Use ASNs if the AS_PATH contains a mixture of 109 Private Use and Non-Private Use ASNs. If such implementations have 110 not been updated to recognize the new range of ASNs in this document 111 and a mix of old and new range Private Use ASNs exist in the path, 112 these implementations may cease to remove any Private Use ASNs from 113 the AS_PATH. Normal AS_PATH filtering may be used to prevent 114 prefixes originating from Private Use ASNs from being advertised to 115 the global Internet. Using AS_PATH filtering to filter the new range 116 of Private Use ASNs on a network may also mitigate the leaking of 117 Private Use ASNs to the global Internet in certain cases. These 118 cases include the case where a network is reliant on AS_PATH 119 manipulation features that have not been updated to recognize the new 120 range as described above. 122 5. Acknowledgements 124 The author would like to acknowledge Christopher Morrow, Jason 125 Schiller, and John Scudder for their advice on how to pursue this 126 change. The author would also like to thank Brian Dickson, David 127 Farmer, Jeffrey Haas, Nick Hilliard, Warren Kumari, and Jeff Wheeler 128 for their comments and suggestions. 130 6. IANA Considerations 132 [Note to IANA, NOT for publication: The IANA should update the "16- 133 bit Autonomous System Numbers" registry to reference this RFC (when 134 published) for the existing Private Use reservation. Further, to 135 maintain consistency from an operator standpoint, it is suggested 136 that the end of the "32-bit Autonomous System Numbers" range be 137 reserved for Private Use, and a size of 94,967,295 (value to replace 138 TBD1 below) is suggested corresponding to the range of 4200000000 139 (value to replace TBD2 below) to 4294967294 (value to replace TBD3 140 below).] 142 IANA has reserved, for Private Use, a contiguous block of 1023 143 Autonomous System numbers from the "16-bit Autonomous System Numbers" 144 registry, namely 64512 - 65534 inclusive. 146 IANA has also reserved, for Private Use, a contiguous block of TBD1 147 Autonomous System numbers from the "32-bit Autonomous System Numbers" 148 registry, namely TBD2 - TBD3 inclusive. 150 These reservations have been documented in the IANA Autonomous System 151 Numbers Registry [IANA.AS]. 153 7. Security Considerations 155 This document does not introduce any additional security concerns in 156 regards to Private Use ASNs. 158 8. References 160 8.1. Normative References 162 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 163 Requirement Levels", BCP 14, RFC 2119, March 1997. 165 [RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway 166 Protocol 4 (BGP-4)", RFC 4271, January 2006. 168 [RFC6793] Vohra, Q. and E. Chen, "BGP Support for Four-Octet 169 Autonomous System (AS) Number Space", RFC 6793, 170 December 2012. 172 8.2. Informative References 174 [IANA.AS] IANA, "Autonomous System (AS) Numbers", December 2012, 175 . 177 [RFC1930] Hawkinson, J. and T. Bates, "Guidelines for creation, 178 selection, and registration of an Autonomous System (AS)", 179 BCP 6, RFC 1930, March 1996. 181 Author's Address 183 Jon Mitchell 184 Microsoft Corporation 185 12012 Sunset Hills Road 186 Reston, VA 20190 187 USA 189 Email: Jon.Mitchell@microsoft.com