Network Working Group G. Huston
Request for Comments: 5398 December 2008
Category: Informational
Autonomous System (AS) Number Reservation for Documentation Use
1. Introduction
To reduce the likelihood of conflict and confusion when relating documented examples to deployed systems, two blocks of Autonomous System numbers (ASNs) are reserved for use in examples in RFCs, books, documentation, and the like. This document describes the reservation of two blocks of ASNs as reserved numbers for use in documentation.
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RFC 5398 ASN Documentation Reservation December 2008
Similar considerations have been applied to IPv4 addresses [IANA.IPv4], IPv6 addresses [RFC3849], and domain names [RFC2606], and reservations have been made for similar purposes.
2. ASNs for Documentation Use
To allow documentation to accurately describe deployment examples, the use of public or private-use AS numbers is inappropriate, and a reserved block of AS numbers is required. This ensures that documentation does not clash with public- or private-use AS numbers in deployed networks, and mitigates the risks to operational integrity of the network through inappropriate use of documentation to perform literal configuration of routing elements on production systems.
3. Operational Implications
This assignment implies that BGP operational configurations should not peer with neighboring ASes that are numbered from this reserved AS number set.
4. IANA Considerations
IANA has reserved a contiguous block of 16 Autonomous System numbers from the unallocated number range within the "16-bit" number set for documentation purposes, namely 64496 - 64511, and a contiguous block of 16 Autonomous System numbers from the "32-bit" number set for documentation, namely 65536 - 65551. These reservations have been documented in the IANA AS Number Registry [IANA.AS].
5. Security Considerations
AS number reservations do not have any direct impact on Internet infrastructure security.
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RFC 5398 ASN Documentation Reservation December 2008 6. AcknowledgementsThe author acknowledges the work of Tomoya Yoshida, Gaurab Upadhaya, and Philip Smith in authoring a policy proposal that was submitted to the APNIC Policy Process in 2008 relating to the reservation of AS numbers for documentation purposes.
7. Informative References
[IANA.AS] IANA, "Autonomous System (AS) Numbers", Sep 2008,