Unique Origin Autonomous System Numbers (ASNs) per Node for Globally Anycasted Services
RFC 6382

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Internet Engineering Task Force (IETF)                      D. McPherson
Request for Comments: 6382                                   R. Donnelly
BCP: 169                                                       F. Scalzo
Category: Best Current Practice                           Verisign, Inc.
ISSN: 2070-1721                                             October 2011

             Unique Origin Autonomous System Numbers (ASNs)
                per Node for Globally Anycasted Services

Abstract

   This document makes recommendations regarding the use of unique
   origin autonomous system numbers (ASNs) per node for globally
   anycasted critical infrastructure services in order to provide
   routing system discriminators for a given anycasted prefix.  Network
   management and monitoring techniques, or other operational
   mechanisms, may employ this new discriminator in whatever manner best
   accommodates their operating environment.

Status of This Memo

   This memo documents an Internet Best Current Practice.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   BCPs is available in Section 2 of RFC 5741.

   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/rfc6382.

Copyright Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

McPherson, et al.         Best Current Practice                 [Page 1]
RFC 6382           Unique ASNs for Anycasted Services       October 2011

Table of Contents

   1. Introduction ....................................................2
   2. Terminology .....................................................4
   3. Recommendation for Unique Origin ASNs ...........................5
   4. Additional Recommendations for Globally Anycasted Services ......6
   5. Security Considerations .........................................7
   6. Deployment Considerations .......................................7
   7. Acknowledgements ................................................9
   8. IANA Considerations .............................................9
   9. References ......................................................9
      9.1. Normative References .......................................9
      9.2. Informative References .....................................9

1.  Introduction

   IP anycasting [RFC4786] has been deployed for an array of network
   services since the early 1990s.  It provides a mechanism for a given
   network resource to be available in a more distributed manner,
   locally and/or globally, with a more robust and resilient footprint,
   commonly yielding better localization and absorption of systemic
   query loads, as well as better protections in the face of distributed
   denial-of-service (DDoS) attacks, network partitions, and other
   similar incidents.  A large part of the Internet root DNS
   infrastructure, as well as many other resources, has been anycasted
   for nearly a decade.

   While the benefits realized by anycasting network services is proven,
   some issues do emerge with asserting routing system reachability for
   a common network identifier from multiple locations.  Specifically,
   anycasting in BGP requires injection of reachability information in
   the routing system for a common IP address prefix from multiple
   locations.  These anycasted prefixes and network services have
   traditionally employed a common origin autonomous system number (ASN)
   in order to preserve historically scarce 16-bit AS number space
   utilized by BGP for routing domain identifiers in the global routing
   system.  Additionally, a common origin AS number was used in order to
   ease management overhead of resource operations associated with
   acquiring and maintaining multiple discrete AS numbers as well as to
   avoid triggering various operations-oriented reporting functions
   aimed at identifying "inconsistent origin AS announcements" observed
   in the routing system.  As a result, the representation of routing
   system path attributes associated with those service instances, and
   that anycasted prefix itself, typically bear no per-instance