IPv6 Formal Anycast Addresses and Functional Anycast Addresses
draft-smith-6man-form-func-anycast-addresses-01

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Internet Engineering Task Force                                 M. Smith
Internet-Draft                                          November 3, 2019
Updates: RFC4291, RFC4443, RFC6724 (if
         approved)
Intended status: Standards Track
Expires: May 6, 2020

     IPv6 Formal Anycast Addresses and Functional Anycast Addresses
            draft-smith-6man-form-func-anycast-addresses-01

Abstract

   Currently, IPv6 anycast addresses are chosen from within the existing
   IPv6 unicast address space, with the addresses nominated as anycast
   addresses through configuration.  An alternative scheme would be to
   have a special class of addresses for use as anycast addresses.  This
   memo proposes a distinct general anycast addressing class for IPv6,
   and a more specific scheme for functional anycast addresses.

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
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on May 6, 2020.

Copyright Notice

   Copyright (c) 2019 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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   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
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Smith                      Expires May 6, 2020                  [Page 1]
Internet-DraftIPv6 Formal And Functional Anycast Addresses November 2019

   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.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Drawbacks of Informal Anycast Addresses . . . . . . . . . . .   4
   4.  Formal Anycast Addresses  . . . . . . . . . . . . . . . . . .   5
     4.1.  Address Format  . . . . . . . . . . . . . . . . . . . . .   5
     4.2.  Address Fields  . . . . . . . . . . . . . . . . . . . . .   5
       4.2.1.  Formal Anycast Prefix . . . . . . . . . . . . . . . .   6
       4.2.2.  Visible Scope . . . . . . . . . . . . . . . . . . . .   6
       4.2.3.  Anycast Identifier Format . . . . . . . . . . . . . .   6
       4.2.4.  Anycast Identifier  . . . . . . . . . . . . . . . . .   6
     4.3.  Anycast Address Registration Protocol . . . . . . . . . .   6
     4.4.  Network Service Provider Visible Scope  . . . . . . . . .   7
     4.5.  Link-Local Visible Scope  . . . . . . . . . . . . . . . .   7
     4.6.  ICMPv6 Destination Unreachable Message  . . . . . . . . .   8
     4.7.  Default Address Selection . . . . . . . . . . . . . . . .   9
       4.7.1.  Formal Anycast Scope Comparison . . . . . . . . . . .   9
       4.7.2.  Source Address Selection  . . . . . . . . . . . . . .   9
       4.7.3.  Destination Address Selection . . . . . . . . . . . .   9
     4.8.  Non-Local Anycast Forwarding  . . . . . . . . . . . . . .  10
     4.9.  Advice on Structuring the Anycast Identifier Field Values  11
   5.  Functional Anycast Addresses  . . . . . . . . . . . . . . . .  13
     5.1.  Features  . . . . . . . . . . . . . . . . . . . . . . . .  13
     5.2.  Address Format  . . . . . . . . . . . . . . . . . . . . .  14
     5.3.  Assignment of Anycast Function Identifiers  . . . . . . .  16
     5.4.  Assigned Anycast Function Identifiers . . . . . . . . . .  17
     5.5.  Sources of Inspiration for Anycast Function Identifiers .  18
     5.6.  Global Scope Functional Anycast Addresses on the Internet  19
     5.7.  Example Use Cases . . . . . . . . . . . . . . . . . . . .  20
       5.7.1.  Devices Factory Configured with NTP Functional
               Anycast Addresses . . . . . . . . . . . . . . . . . .  20
       5.7.2.  Branch Office DNS Resolvers . . . . . . . . . . . . .  22
       5.7.3.  Automatic eBGP Session Establishment  . . . . . . . .  23
       5.7.4.  An ISP's Anycast DNS Resolvers  . . . . . . . . . . .  25
       5.7.5.  Microservices Architecture Applications . . . . . . .  27
       5.7.6.  Global Time Distribution Network  . . . . . . . . . .  27
       5.7.7.  Multipath Transport Layer Protocols . . . . . . . . .  27