Distributed Prefix Assignment Algorithm
RFC 7695

Document Type RFC - Proposed Standard (November 2015; No errata)
Last updated 2015-11-24
Replaces draft-pfister-homenet-prefix-assignment
Stream IETF
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Stream WG state Submitted to IESG for Publication
Document shepherd Mark Townsley
Shepherd write-up Show (last changed 2015-04-21)
IESG IESG state RFC 7695 (Proposed Standard)
Consensus Boilerplate Yes
Telechat date
Responsible AD Terry Manderson
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IANA IANA review state Version Changed - Review Needed
IANA action state No IC
Internet Engineering Task Force (IETF)                        P. Pfister
Request for Comments: 7695                                   B. Paterson
Category: Standards Track                                  Cisco Systems
ISSN: 2070-1721                                                 J. Arkko
                                                                Ericsson
                                                           November 2015

                Distributed Prefix Assignment Algorithm

Abstract

   This document specifies a distributed algorithm for dividing a set of
   prefixes in a manner that allows for automatic assignment of sub-
   prefixes that are unique and non-overlapping.  Used in conjunction
   with a protocol that provides flooding of information among a set of
   participating nodes, prefix configuration within a network may be
   automated.

Status of This Memo

   This is an Internet Standards Track document.

   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
   Internet Standards 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/rfc7695.

Copyright Notice

   Copyright (c) 2015 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.

Pfister, et al.              Standards Track                    [Page 1]
RFC 7695               Prefix Assignment Algorithm         November 2015

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Definitions . . . . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Subroutine-Specific Terminology . . . . . . . . . . . . .   6
   3.  Applicability Statement . . . . . . . . . . . . . . . . . . .   7
   4.  Algorithm Specification . . . . . . . . . . . . . . . . . . .   9
     4.1.  Prefix Assignment Algorithm Subroutine  . . . . . . . . .   9
     4.2.  Overriding and Destroying Existing Assignments  . . . . .  12
     4.3.  Other Events  . . . . . . . . . . . . . . . . . . . . . .  13
   5.  Prefix Selection Considerations . . . . . . . . . . . . . . .  14
   6.  Implementation Capabilities and Node Behavior . . . . . . . .  16
   7.  Algorithm Parameters  . . . . . . . . . . . . . . . . . . . .  17
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  17
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  18
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  18
     11.2.  Informative References . . . . . . . . . . . . . . . . .  18
   Appendix A.  Static Configuration Example . . . . . . . . . . . .  19
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  20
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  20

1.  Introduction

   This document specifies a distributed algorithm for automatic prefix
   assignment.  The algorithm provides a generic alternative to
   centralized (human- or software-based) approaches for network prefix
   and address assignment.  Although it does not have to be configured
   to operate properly, it supports custom configuration by means of
   variable priority assignments, and can therefore be used in fully
   autonomic as well as configured networks.  This document focuses on
   the algorithm itself and therefore context-specific considerations
   (such as the process of selecting a prefix value and length when
   making a new assignment) are out of scope.

   The algorithm makes use of a flooding mechanism allowing
   participating nodes to advertise prefixes assigned to the links to
   which they are directly connected or for other purposes, e.g., for
   private assignment or prefix delegation.  Advertising a prefix
   therefore serves two purposes.  It is a claim that a prefix is in
   use, meaning that no other node may advertise an overlapping prefix
   (unless it has a greater priority).  And, it is a way for other nodes
   to know which prefixes have been assigned to the links to which they
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