Architectural Considerations of IP Anycast
draft-iab-anycast-arch-implications-07

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Document Type Active Internet-Draft
Last updated 2013-05-06
Stream IAB
Intended RFC status Informational
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Internet Engineering Task Force                             D. McPherson
Internet-Draft                                            Verisign, Inc.
Intended status: Informational                                   D. Oran
Expires: November 7, 2013                                  Cisco Systems
                                                               D. Thaler
                                                   Microsoft Corporation
                                                            E. Osterweil
                                                          Verisign, Inc.
                                                             May 6, 2013

               Architectural Considerations of IP Anycast
                <draft-iab-anycast-arch-implications-07>

Abstract

   This memo discusses architectural implications of IP anycast, and
   provides some historical analysis of anycast use by various IETF
   protocols.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
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   This Internet-Draft will expire on November 7, 2013.

Copyright Notice

   Copyright (c) 2013 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
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   (http://trustee.ietf.org/license-info) in effect on the date of
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   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.

Table of Contents

   1.  Overview . . . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Background . . . . . . . . . . . . . . . . . . . . . . . . . .  4
     2.1.  Anycast History  . . . . . . . . . . . . . . . . . . . . .  4
     2.2.  Anycast in IPv6  . . . . . . . . . . . . . . . . . . . . .  6
     2.3.  DNS Anycast  . . . . . . . . . . . . . . . . . . . . . . .  6
     2.4.  BCP 126 on Operation of Anycast Services . . . . . . . . .  8
   3.  Principles . . . . . . . . . . . . . . . . . . . . . . . . . .  8
     3.1.  Layering and Resiliency  . . . . . . . . . . . . . . . . .  8
     3.2.  Anycast Addresses as Destinations  . . . . . . . . . . . .  9
     3.3.  Anycast Addresses as Sources . . . . . . . . . . . . . . . 10
     3.4.  Service Discovery  . . . . . . . . . . . . . . . . . . . . 10
   4.  Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
     4.1.  Regarding Widespread Anycast Use . . . . . . . . . . . . . 11
     4.2.  Transport Implications . . . . . . . . . . . . . . . . . . 11
     4.3.  Stateful Firewalls, Middleboxes and Anycast  . . . . . . . 12
     4.4.  Security Considerations  . . . . . . . . . . . . . . . . . 12
     4.5.  Deployment Considerations  . . . . . . . . . . . . . . . . 14
   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 15
   6.  Conclusions  . . . . . . . . . . . . . . . . . . . . . . . . . 15
   7.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 15
   8.  Informative References . . . . . . . . . . . . . . . . . . . . 15
   Appendix A.  IAB Members . . . . . . . . . . . . . . . . . . . . . 19
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19

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1.  Overview

   IP anycast is used for at least one critical Internet service, that
   of the Domain Name System [RFC1035] root servers.  As of early 2009,
   at least 10 of the 13 root name servers were using IP anycast
   [RSSAC29].  Use of IP anycast is growing for other applications as
   well.  It has been deployed for over a decade for DNS resolution
   services and is currently used by several DNS Top Level Domain (TLD)
   operators.  IP anycast is also used for other services in operational
   environments, including Network Time Protocol (NTP) [RFC5905]
   services.

   Anycast addresses are syntactically indistinguishable from unicast
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