Internet DRAFT - draft-ietf-idr-as-private-reservation
draft-ietf-idr-as-private-reservation
Network Working Group J. Mitchell
Internet-Draft Microsoft Corporation
Updates: 1930 (if approved) May 29, 2013
Intended status: Best Current Practice
Expires: November 30, 2013
Autonomous System (AS) Reservation for Private Use
draft-ietf-idr-as-private-reservation-05
Abstract
This document describes the reservation of Autonomous System numbers
(ASNs) that are for Private Use only and MUST 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
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This Internet-Draft will expire on November 30, 2013.
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
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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, Border Gateway Protocol (BGP), documented in [RFC4271], has
seen deployment in new application domains, such as datacenter
networks, which require a larger Private Use AS Space.
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 these 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. 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].
3. Private Use ASNs
To allow the continued growth of usage of the BGP protocol in new
network applications that utilize Private Use ASNs, two ranges of
ASNs are reserved by this document in Section 6. 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].
4. Operational Considerations
If Private Use ASNs are used and prefixes are originated from these
ASNs, Private Use ASNs MUST be removed from AS path attributes
(including AS4_PATH if utilizing four-octet AS number space) before
being advertised to the global Internet. Operators SHOULD ensure all
EBGP speakers support [RFC6793] and 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 in the four-octet AS
number space. Some existing implementations that remove Private Use
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ASNs from the AS_PATH are known to not remove Private Use ASNs if the
AS_PATH contains a mixture of Private Use and Non-Private Use ASNs.
If such implementations have not been updated to recognize the new
range of ASNs in this document and a mix of old and new range Private
Use ASNs exist in the AS4_PATH, these implementations will likely
cease to remove any Private Use ASNs from either of the AS path
attributes. Normal AS path filtering MAY also be used to prevent
prefixes originating from Private Use ASNs from being advertised to
the global Internet.
5. 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, Joel Jaeggli, Warren Kumari, and
Jeff Wheeler for their comments and suggestions.
6. IANA Considerations
[Note to IANA, this paragraph to be removed upon publication: The
IANA should update the "16-bit Autonomous System Numbers" registry to
reference this RFC for the existing Private Use reservation. The end
of the "32-bit Autonomous System Numbers" range will be reserved for
Private Use, and a size of 94,967,295 (value to replace TBD1 below)
corresponding to the range of 4200000000 (value to replace TBD2
below) to 4294967294 (value to replace TBD3 below). Text after this
sentence should be published in the document.]
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.
These reservations have been documented in the IANA Autonomous System
Numbers Registry [IANA.AS].
7. Security Considerations
Private Use ASNs do not raise any unique security concerns. Loss of
connectivity might result from inappropriate use of them,
specifically outside of a single organization, since they are not
globally unique. This loss of connectivity is limited to the
organization using Private Use ASNs inappropriately or without
reference to Section 4. General BGP security considerations are
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discussed in [RFC4271] and [RFC4272]. Identification of the
originator of a route with a Private Use ASN in the AS path would
have to be done by tracking the route back to the neighboring
globally unique AS in the path or by inspecting other attributes.
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[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.
8.2. Informative References
[IANA.AS] IANA, "Autonomous System (AS) Numbers", May 2013,
<http://www.iana.org/assignments/as-numbers/>.
[RFC1930] Hawkinson, J. and T. Bates, "Guidelines for creation,
selection, and registration of an Autonomous System (AS)",
BCP 6, RFC 1930, March 1996.
[RFC4272] Murphy, S., "BGP Security Vulnerabilities Analysis", RFC
4272, January 2006.
Author's Address
Jon Mitchell
Microsoft Corporation
One Microsoft Way
Redmond, WA 98052
USA
Email: Jon.Mitchell@microsoft.com
Mitchell Expires November 30, 2013 [Page 4]
