Internet DRAFT - draft-fan-sunset4-router-id


Network Working Group                                             P. Fan
Internet-Draft                                              China Mobile
Intended status: Informational                             June 20, 2014
Expires: December 22, 2014

             Managing Router Identifiers during IPv4 Sunset


   This document describes problems of managing protocol identifiers
   when turning off IPv4 and migrating to IPv6 only network, with some
   potential solutions discussed.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
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   This Internet-Draft will expire on December 22, 2014.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Problem Statement . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Solution Ideas  . . . . . . . . . . . . . . . . . . . . . . .   2
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   3
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   3

1.  Introduction

   There are many places in IETF protocols where a unique identifier is
   needed.  An identifier is typically referred to as a router ID or
   system ID identifying a router/system running the protocol, and is
   traditionally designed to be a 32-bit number.  Usually the IDs are
   required to be unique across some domain, but the actual value is not
   relevant.  The value of IDs is often conventionally chosen to be an
   IPv4 address on the router, and in many implementations the IDs are
   even expressed in dotted decimal notation.  There is some operational
   convenience of the common practice of tying the IDs to IP addresses:

   1.  A human-readable set of information is easy for network operators
       to deal with.

   2.  IDs can be auto-configured, saving the work of planning and

   3.  It is helpful to quickly perform diagnosis and troubleshooting,
       and easy to identify the availability and location of the
       identified router.

2.  Problem Statement

   In an IPv6 only network, there are no IP addresses that can be
   directly used to number an ID.  IDs have to be planned individually
   to meet the uniqueness requirement, and the advantages of tying to IP
   addresses indicated in section 1 are lost.

3.  Solution Ideas

   If the ID is required to correspond to some information on the router
   or system, e.g. an IP address, the ID should be extended to meet the
   requirement; if the value is irrelevant and only needs to be unique,
   there has been suggestion about avoiding protocol change.

   One can use some record keeping mechanisms, e.g.  DNS or even text
   file, to associate IDs and IPv6 addresses to retain some of the

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   operational convenience, though extra record keeping does introduce
   additional work.  Record keeping should be reliable enough so as to
   be reachable when a network problem occurs.  Another option is to use
   some external provisioning system, e.g. network management system, to
   manage and allocate the IDs.

   Another possible solution is to embed the ID into an IPv6 address,
   e.g. use a /96 IPv6 prefix and append it with a 32-bit long ID, then
   an ID is naturally tied to an IP address.

   The above ideas require IDs be planned and generated in advance and
   meet the uniqueness requirement.  IDs can be manually planned,
   possibly with some hierarchy or design rule, or can be created
   automatically.  A simple way of automatic ID creation is to generate
   pseudo-random numbers, and one can use another source of data such as
   the clock time at boot or configuration time to provide additional
   entropy during the generation of unique IDs.

   One can also hash an IPv6 address down to a value as ID.  It is
   necessary to be able to override the hashed value, and desirable if
   hash is provided by the router implementation.  The hash algorithm is
   supposed to be known and the same across the domain.  Since typically
   the number of routers in a domain is far smaller than the value range
   of IDs, the hashed IDs are hardly likely to conflict with each other,
   as long as the hash algorithm is not designed too badly.

4.  Security Considerations


5.  IANA Considerations


6.  Acknowledgements

   Thanks to Fred Baker, Shane Amante, David Farmer, Wes George for
   their valuable ideas in forming this document.

Author's Address

   Peng Fan
   China Mobile
   32 Xuanwumen West Street, Xicheng District
   Beijing  100053
   P.R. China


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