draft-ietf-idr-last-as-reservation-07.txt   rfc7300.txt 
IDR J. Haas Internet Engineering Task Force (IETF) J. Haas
Internet-Draft Juniper Networks Request for Comments: 7300 Juniper Networks
Updates: 1930 (if approved) J. Mitchell BCP: 6 J. Mitchell
Intended status: Best Current Practice Microsoft Corporation Updates: 1930 Microsoft Corporation
Expires: November 22, 2014 May 21, 2014 Category: Best Current Practice July 2014
ISSN: 2070-1721
Reservation of Last Autonomous System (AS) Numbers Reservation of Last Autonomous System (AS) Numbers
draft-ietf-idr-last-as-reservation-07
Abstract Abstract
This document reserves two Autonomous System numbers (ASNs) at the This document reserves two Autonomous System Numbers (ASNs) at the
end of the 16 bit and 32 bit ranges, described in this document as end of the 16-bit and 32-bit ranges, described in this document as
"Last ASNs" and provides guidance to implementers and operators on "Last ASNs", and provides guidance to implementers and operators on
their use. This document updates section 10 of RFC 1930. their use. This document updates Section 10 of RFC 1930.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This memo documents an Internet Best Current Practice.
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 This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It has been approved for publication by the Internet
time. It is inappropriate to use Internet-Drafts as reference Engineering Steering Group (IESG). Further information on BCPs is
material or to cite them other than as "work in progress." available in Section 2 of RFC 5741.
This Internet-Draft will expire on November 22, 2014. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7300.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
1. Introduction 1. Introduction
IANA has reserved the last Autonomous System Number (ASN), 65535, of Over a decade ago, IANA reserved the last Autonomous System Number
the 16 bit autonomous system number range for over a decade with the (ASN) of the 16-bit ASN range, 65535, with the intention that it not
intention that it not be used by network operators running BGP be used by network operators running BGP [RFC4271]. Since the
[RFC4271]. Since the introduction of BGP Support for Four-Octet AS introduction of "BGP Support for Four-Octet Autonomous System (AS)
Number Space [RFC6793], IANA has also reserved the last ASN of the 32 Number Space" [RFC6793], IANA has also reserved the last ASN of the
bit autonomous system number range, 4294967295. This reservation has 32-bit autonomous system number range, 4294967295. This reservation
been documented in the IANA Autonomous System Numbers Registry has been documented in the IANA "Autonomous System (AS) Numbers"
[IANA.AS]. Although these "Last ASNs" border on Private Use ASN registry [IANA.AS]. Although these "Last ASNs" border on Private Use
[RFC6996] ranges, they are not defined or reserved as Private Use ASN [RFC6996] ranges, they are not defined or reserved as Private Use
ASNs by [IANA.AS]. This document describes the reasoning for ASNs by [IANA.AS]. This document describes the reasoning for
reserving these Last ASNs and provides guidance both to operators and reserving Last ASNs and provides guidance both to operators and to
to implementers on their use. implementers on their use.
2. Requirements Language 2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
3. Reasons for Last ASNs Reservation 3. Reasons for Reservation of the Last ASNs
A subset of the BGP communities of ASN 65535, the last ASN of the 16 A subset of the BGP communities of ASN 65535, the last ASN of the
bit range, are reserved for use by Well-known communities as 16-bit range, are reserved for use by Well-known Communities as
described in [RFC1997] and [IANA.WK]. Although this is not currently described in [RFC1997] and [IANA.WK]. Although this is not currently
true of ASN 4294967295, if there is a future need for another Special true of ASN 4294967295, if there is a future need for another Special
Use ASN that is not designed to be globally routable, or the Use ASN that is not designed to be globally routable, or for the
associated BGP communities of such an ASN, ASN 4294967295 could be a associated BGP communities of such an ASN, ASN 4294967295 could be a
valid candidate for such purpose. This document does not prescribe valid candidate for such purpose. This document does not prescribe
any such Special Use to this ASN at the time of publication. any such Special Use to this ASN at the time of publication.
4. Operational Considerations 4. Operational Considerations
Operators SHOULD NOT use these Last ASNs for any other purpose or as Operators SHOULD NOT use these Last ASNs for any other purpose or as
Private Use ASNs. Operational use of these Last ASNs could have Private Use ASNs. Operational use of these Last ASNs could have
undesirable results. For example; use of AS 65535 as if it were a undesirable results. For example; use of AS 65535 as if it were a
Private Use ASN, may result in inadvertent use of BGP Well-known Private Use ASN, may result in inadvertent use of BGP Well-known
Community values [IANA.WK], causing undesirable routing behavior. Community values [IANA.WK], causing undesirable routing behavior.
These last ASNs MUST NOT be advertised to the global Internet within Last ASNs MUST NOT be advertised to the global Internet within
AS_PATH or AS4_PATH attributes. Operators SHOULD filter Last ASNs AS_PATH or AS4_PATH attributes. Operators SHOULD filter Last ASNs
within the AS_PATH and AS4_PATH attributes. within the AS_PATH and AS4_PATH attributes.
5. Implementation Considerations 5. Implementation Considerations
While these Last ASNs are reserved, they remain valid ASNs from a BGP While Last ASNs are reserved, they remain valid ASNs from a BGP
protocol perspective. Therefore, implementations of BGP [RFC4271] perspective. Therefore, implementations of BGP [RFC4271] SHOULD NOT
SHOULD NOT treat the use of these Last ASNs as any type of protocol treat the use of Last ASNs as any type of protocol error. However,
error. However, implementations MAY generate a local warning message if a Last ASN is configured as the local AS, implementations MAY
indicating improper use of a reserved ASN. generate a warning message indicating improper use of a reserved ASN.
Implementations that provide tools that filter Private Use ASNs Implementations that provide tools that filter Private Use ASNs
within the AS_PATH and AS4_PATH attributes MAY also include these within the AS_PATH and AS4_PATH attributes MAY also include Last
Last ASNs. ASNs.
6. IANA Considerations 6. IANA Considerations
[Note to IANA, TO BE REMOVED BEFORE PUBLICATION: IANA please update
the reservations for values 65535 and 4294967295 in the registries
mentioned below to reference this document.]
IANA has reserved last Autonomous System number 65535 from the IANA has reserved last Autonomous System number 65535 from the
"16-bit Autonomous System Numbers" registry for the reasons described "16-bit Autonomous System Numbers" registry for the reasons described
in this document. in this document.
IANA has also reserved last Autonomous System number 4294967295 from IANA has also reserved last Autonomous System number 4294967295 from
the "32-bit Autonomous System Numbers" registry for the reasons the "32-bit Autonomous System Numbers" registry for the reasons
described in this document. described in this document.
These reservations have been documented in the IANA Autonomous System These reservations have been documented in the IANA "Autonomous
Numbers Registry [IANA.AS] and the IANA Special-Purpose AS Numbers System (AS) Numbers" registry [IANA.AS] and the IANA "Special-Purpose
Registry [IANA.SpecialAS]. Autonomous System (AS) Numbers" registry [IANA.SpecialAS].
7. Security Considerations 7. Security Considerations
This document does not introduce any additional security concerns in This document does not introduce any additional security concerns in
regards to usage of Last ASNs. Although the BGP protocol is designed regards to usage of Last ASNs. Although the BGP is designed to allow
to allow usage of these Last ASNs, security issues related to BGP usage of Last ASNs, security issues related to BGP implementation
implementation errors could be triggered by Last ASN usage. errors could be triggered by Last ASN usage.
8. References 8. References
8.1. Normative References 8.1. Normative References
[IANA.AS] IANA, , "Autonomous System (AS) Numbers", May 2014, [IANA.AS] IANA, "Autonomous System (AS) Numbers",
<http://www.iana.org/assignments/as-numbers/>. <http://www.iana.org/assignments/as-numbers/>.
[IANA.SpecialAS] [IANA.SpecialAS]
IANA, , "Special-Purpose Autonomous System (AS) Numbers", IANA, "Special-Purpose Autonomous System (AS) Numbers",
May 2014, <http://www.iana.org/assignments/ <http://www.iana.org/assignments/
iana-as-numbers-special-registry/>. iana-as-numbers-special-registry/>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway [RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
Protocol 4 (BGP-4)", RFC 4271, January 2006. Protocol 4 (BGP-4)", RFC 4271, January 2006.
[RFC6793] Vohra, Q. and E. Chen, "BGP Support for Four-Octet [RFC6793] Vohra, Q. and E. Chen, "BGP Support for Four-Octet
Autonomous System (AS) Number Space", RFC 6793, December Autonomous System (AS) Number Space", RFC 6793, December
2012. 2012.
8.2. Informative References 8.2. Informative References
[IANA.WK] IANA, , "Border Gateway Protocol (BGP) Well-known [IANA.WK] IANA, "Border Gateway Protocol (BGP) Well-known
Communities", May 2014, <http://www.iana.org/assignments/ Communities", <http://www.iana.org/assignments/
bgp-well-known-communities/>. bgp-well-known-communities/>.
[RFC1997] Chandrasekeran, R., Traina, P., and T. Li, "BGP [RFC1997] Chandrasekeran, R., Traina, P., and T. Li, "BGP
Communities Attribute", RFC 1997, August 1996. Communities Attribute", RFC 1997, August 1996.
[RFC6996] Mitchell, J., "Autonomous System (AS) Reservation for [RFC6996] Mitchell, J., "Autonomous System (AS) Reservation for
Private Use", BCP 6, RFC 6996, July 2013. Private Use", BCP 6, RFC 6996, July 2013.
Appendix A. Acknowledgments Appendix A. Acknowledgments
The authors would like to thank Michelle Cotton and Elwyn Davis for The authors would like to thank Michelle Cotton and Elwyn Davies for
encouraging the proper documentation of the reservation of these ASNs encouraging the proper documentation of the reservation of these
and David Farmer for his contributions to the document. ASNs, and David Farmer for his contributions to the document.
Authors' Addresses Authors' Addresses
Jeffrey Haas Jeffrey Haas
Juniper Networks Juniper Networks
Email: jhaas@juniper.net EMail: jhaas@juniper.net
Jon Mitchell Jon Mitchell
Microsoft Corporation Microsoft Corporation
One Microsoft Way One Microsoft Way
Redmond, WA 98052 Redmond, WA 98052
USA USA
Email: Jon.Mitchell@microsoft.com EMail: Jon.Mitchell@microsoft.com
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