draft-ietf-idr-last-as-reservation-01.txt   draft-ietf-idr-last-as-reservation-02.txt 
IDR J. Haas IDR J. Haas
Internet-Draft Juniper Networks Internet-Draft Juniper Networks
Intended status: Informational J. Mitchell Intended status: Informational J. Mitchell
Expires: April 18, 2014 Microsoft Corporation Expires: August 10, 2014 Microsoft Corporation
October 15, 2013 February 6, 2014
Reservation of Last Autonomous System (AS) Numbers Reservation of Last Autonomous System (AS) Numbers
draft-ietf-idr-last-as-reservation-01 draft-ietf-idr-last-as-reservation-02
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. their use.
Status of This Memo Status of This Memo
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 18, 2014. This Internet-Draft will expire on August 10, 2014.
Copyright Notice Copyright Notice
Copyright (c) 2013 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 IANA has reserved the last Autonomous System Number (ASN), 65535, of
the 16 bit autonomous system number range for over a decade with the the 16 bit autonomous system number range for over a decade with the
intention that it not be used by network operators running BGP intention that it not be used by network operators running BGP
[RFC4271]. Since the introduction of BGP Support for Four-Octet AS [RFC4271]. Since the introduction of BGP Support for Four-Octet AS
Number Space [RFC6793], IANA has also reserved the ASN of the 32 bit Number Space [RFC6793], IANA has also reserved the last ASN of the 32
autonomous system number range, 4294967295. This reservation has bit autonomous system number range, 4294967295. This reservation has
been documented in the IANA Autonomous System Numbers Registry been documented in the IANA Autonomous System Numbers Registry
[IANA.AS]. Although these "Last ASNs" border on Private Use ASN [IANA.AS]. Although these "Last ASNs" border on Private Use ASN
[RFC6996] ranges, they are not defined or reserved as Private Use [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 these Last ASNs and provides guidance both to operators and
to implementers on their use. to 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",
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4. Operational Considerations 4. Operational Considerations
Operators SHOULD NOT use these Last ASNs as if they are Private Use Operators SHOULD NOT use these Last ASNs as if they are Private Use
ASNs or for any other purpose. Operational use of these Last ASNs ASNs or for any other purpose. Operational use of these Last ASNs
could have undesirable results. For example; use of AS 65535 as if could have undesirable results. For example; use of AS 65535 as if
it were a Private Use ASN, may result in inadvertent use of BGP Well- it were a Private Use ASN, may result in inadvertent use of BGP Well-
known Community values [IANA.WK], causing undesireable routing known Community values [IANA.WK], causing undesireable routing
behavior. behavior.
These last ASNs MUST NOT be advertised to the global Internet within These last ASNs MUST NOT be advertised to the global Internet within
AS_PATH or AS4_PATH attributes. Operators that choose to do inbound AS_PATH or AS4_PATH attributes. Operators that choose to do
filtering of Private Use ASNs within the AS_PATH and AS4_PATH filtering of Private Use ASNs within the AS_PATH and AS4_PATH
attributes SHOULD also filter these Last ASNs. attributes SHOULD also filter these Last ASNs.
5. Implementation Considerations 5. Implementation Considerations
While these Last ASNs are reserved, they remain valid ASNs from a BGP While these Last ASNs are reserved, they remain valid ASNs from a BGP
protocol perspective. Therefore, implementations of BGP [RFC4271] protocol perspective. Therefore, implementations of BGP [RFC4271]
SHOULD NOT treat the use of these Last ASNs as any type of protocol SHOULD NOT treat the use of these Last ASNs as any type of protocol
error. However, implementations MAY generate a local warning message error. However, implementations MAY generate a local warning message
indicating improper use of a reserved ASN. 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 these
Last ASNs. Last ASNs.
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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 protocol is designed
to allow usage of these Last ASNs, security issues related to BGP to allow usage of these Last ASNs, security issues related to BGP
implementation errors could be triggered by Last ASN usage. implementation 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", October 2013, [IANA.AS] IANA, , "Autonomous System (AS) Numbers", February 2014,
<http://www.iana.org/assignments/as-numbers/>. <http://www.iana.org/assignments/as-numbers/>.
[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", October 2013, <http://www.iana.org/ Communities", February 2014, <http://www.iana.org/
assignments/bgp-well-known-communities/>. assignments/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. Acknowledgements Appendix A. Acknowledgements
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