Network Working Group                                        M. Blanchet
Internet-Draft                                                  Viagenie
Intended status: Standards Track                       February 26, 2007
Expires: August 30, 2007


                    IPv6 Routing Policies Guidelines
               draft-ietf-v6ops-routing-guidelines-01.txt

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Copyright Notice

   Copyright (C) The IETF Trust (2007).

Abstract

   Guidelines on how to manage and filter IPv6 routes are needed for
   operators of networks, either providers or enterprises.  It describes
   IPv6 routes from the protocol point of view.  It does not discuss
   operational or policy issues such as the maximum length of prefixes
   to filter.  This document is a followup on RFC2772 work but for the
   production IPv6 Internet.  RFC2772 is obsoleted.





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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Address Types . . . . . . . . . . . . . . . . . . . . . . . . . 3
     2.1.  Node-scoped Unicast . . . . . . . . . . . . . . . . . . . . 3
     2.2.  IPv4-Mapped Addresses . . . . . . . . . . . . . . . . . . . 3
     2.3.  Link-scoped Unicast . . . . . . . . . . . . . . . . . . . . 3
     2.4.  Site-scoped Unicast . . . . . . . . . . . . . . . . . . . . 3
     2.5.  Global Unicast  . . . . . . . . . . . . . . . . . . . . . . 3
       2.5.1.  Documentation Prefix  . . . . . . . . . . . . . . . . . 4
       2.5.2.  6to4  . . . . . . . . . . . . . . . . . . . . . . . . . 4
       2.5.3.  Teredo  . . . . . . . . . . . . . . . . . . . . . . . . 4
       2.5.4.  6bone . . . . . . . . . . . . . . . . . . . . . . . . . 4
     2.6.  Default Route . . . . . . . . . . . . . . . . . . . . . . . 4
     2.7.  Multicast . . . . . . . . . . . . . . . . . . . . . . . . . 5
     2.8.  Unknown addresses . . . . . . . . . . . . . . . . . . . . . 5
   3.  Implementing routing policies . . . . . . . . . . . . . . . . . 5
   4.  RPSL Implementation . . . . . . . . . . . . . . . . . . . . . . 5
   5.  Security Considerations . . . . . . . . . . . . . . . . . . . . 6
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 6
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 6
     7.1.  Normative References  . . . . . . . . . . . . . . . . . . . 6
     7.2.  Informative References  . . . . . . . . . . . . . . . . . . 7
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . . . 7
   Intellectual Property and Copyright Statements  . . . . . . . . . . 8


























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.  Introduction

   To maintain stability, efficiency and scalability of the IPv6
   Internet, guidelines for routing policies are needed for operators
   deploying IPv6 networks.  Prior experience on IPv6 routing guidelines
   on the 6bone[RFC2772], practical deployment of the IPv6 internet and
   IPv6 specifications were used as input to this document.

   This document first describes the different types of addresses and
   then summarizes the suggested policies in RPSL.

   "Advertisement" in this document refers to the prefix advertisement,
   not the next-hop.


.  Address Types

2.1.  Node-scoped Unicast

   The node-scoped unicast addresses[RFC4291] such as the loopback
   (::1/128), the unspecified (::/128) must not be advertised in an IGP
   or EGP and should be filtered out when received.

2.2.  IPv4-Mapped Addresses

   IPv4-mapped addresses (::FFFF:0:0/96) [RFC4291] must not be
   advertised and should be filtered out.

2.3.  Link-scoped Unicast

   The link-scoped unicast[RFC4291] routes (fe80::/10) must not be
   advertised in an IGP or EGP and should be filtered out when received.

2.4.  Site-scoped Unicast

   The site-scoped unicast routes, known as Unique-local[RFC4193],
   (fc00::/7) may be advertised in an IGP.  It must not be advertised in
   an EGP connected to the global Internet and should be filtered out
   when received.  However, it may be advertised in an EGP between two
   networks sharing a private interconnect, but must not be advertised
   outside the scope of these networks.  When advertised in an EGP,
   these routes should be of length /48 or smaller.

2.5.  Global Unicast

   The global unicast routes (2000::/3) [RFC4291] may be advertised in
   an IGP or EGP.




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   A minimal EGP routing policy should filter out routes that exceed a
   maximum length.  Determining the maximum length of a global Internet
   route is outside the scope of this document.

   A finer EGP routing policy may use only the allocated address space
   from IANA to registries as specified in
   http://www.iana.org/assignments/ipv6-unicast-address-assignments.
   This would result in better filtering since the non-allocated
   prefixes will be filtered out.

   An even finer EGP routing policy may use only the assigned address
   space from registries to providers as available in the registries
   databases.  This would result in the best filtering since the non-
   assigned prefixes will be filtered out.  However, this requires the
   synchronization of the filters with the registries databases.

2.5.1.  Documentation Prefix

   The 2001:0db8::/32 prefix[RFC3849] is used for documentation purposes
   and must not be advertised in an IGP or EGP and should be filtered
   out when received.

2.5.2.  6to4

   The 6to4[RFC4291][RFC3056] prefix (2002::/16) may be advertised in an
   IGP or EGP, when the site is running a 6to4 relay or offering a 6to4
   transit service.  However, the provider of this service should be
   aware of the implications of running such service[RFC3964], which
   includes some specific filtering rules for 6to4.

2.5.3.  Teredo

   The Teredo[RFC4380] prefix (2001::/32) may be advertised in an IGP or
   EGP, when the site is running a Teredo relay or offering a Teredo
   transit service.

2.5.4.  6bone

   The 6bone experimental network used some experimental allocations,
   such as 5f00::/8[RFC1897] and 3ffe::/16[RFC2471] that were later
   returned to IANA[RFC3701].  These prefixes should not be advertised
   in an EGP unless IANA reallocates them subsequently.

2.6.  Default Route

   The default unicast route (::) may be advertised in an IGP.  It must
   not be advertised in an EGP unless it has been requested by the
   recipient.



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2.7.  Multicast

   Multicast addresses (ff00::/8) [RFC4291] have a 4 bits scope in the
   address field.  Only addresses having the 'E' value in the scope
   field are of global scope, all other values are local or reserved.
   Therefore, only ffXe:: routes may be advertised outside an
   organisation network, where X may be any value.

   Multicast routes must not appear in unicast routing tables.

2.8.  Unknown addresses

   Any non listed address above must not be advertised and should be
   filtered out.  Future work might reserve additional address space for
   protocol use which might require specific routing guidelines.  The
   reader should refer to newer versions of the normative references in
   this document to verify the existence of newer protocol address
   space.


.  Implementing routing policies

   This document focuses on protocol addresses and their use in the
   networks.  It does not discuss any allocation policies and their
   impact on the routing policies, such as /48 Micro-allocations for
   infrastructure providers or maximum length of a unicast prefix.  As
   such, to implement a complete routing policy, one should augment
   these guidelines with the current registry allocation policies and by
   appropriate ingress filtering techniques[RFC3704].


.  RPSL Implementation

   The Route Policy Specification Language(RPSL) [RFC4012] used in route
   registries supports the policies described in this document and
   should be considered to manage route policies.

   The following RPSL code implements the policies described in this
   document.  This code should be considered as an example and should be
   adapted to the target usage.











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   route-set: rs-exclude
   mp-members: ::1/128, ::/128, ::ffff:0:0/96^+, fe80::/10^+,
    2001:0db8::/32^+

   route-set: rs-ula
   mp-members: fc00::/7^+

   route-set: rs-global-unicast
   mp-members: 2000::/3^+

   route-set: rs-6to4
   mp-members: 2002::/16^+

   route-set: rs-teredo
   mp-members: 2001::/32^+

   filter-set: fltr-v6egp
   mp-filter: NOT (rs-exclude AND rs-ula) AND rs-global-unicast

   filter-set: fltr-v6igp
   mp-filter: NOT rs-exclude AND rs-global-unicast


.  Security Considerations

   This document list guidelines that should improve the security of
   networks by the filtering of invalid routing prefixes.


.  Acknowledgements

   Florent Parent, Pekka Savola, Tim Chown, Alain Baudot, Stig Venaas,
   Vincent Jardin, Olaf Bonness, David Green, Gunter Van de Velde,
   Michael Barnes, Fred Baker, Edward Lewis, Marla Azinger, Brian
   Carpenter, Mark Smith and Kevin Loch have provided input and
   suggestions to this document.


.  References

7.1.  Normative References

   [RFC1897]  Hinden, R. and J. Postel, "IPv6 Testing Address
              Allocation", RFC 1897, January 1996.

   [RFC2471]  Hinden, R., Fink, R., and J. Postel, "IPv6 Testing Address
              Allocation", RFC 2471, December 1998.




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   [RFC3056]  Carpenter, B. and K. Moore, "Connection of IPv6 Domains
              via IPv4 Clouds", RFC 3056, February 2001.

   [RFC3849]  Huston, G., Lord, A., and P. Smith, "IPv6 Address Prefix
              Reserved for Documentation", RFC 3849, July 2004.

   [RFC4012]  Blunk, L., Damas, J., Parent, F., and A. Robachevsky,
              "Routing Policy Specification Language next generation
              (RPSLng)", RFC 4012, March 2005.

   [RFC4193]  Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
              Addresses", RFC 4193, October 2005.

   [RFC4291]  Hinden, R. and S. Deering, "IP Version 6 Addressing
              Architecture", RFC 4291, February 2006.

   [RFC4380]  Huitema, C., "Teredo: Tunneling IPv6 over UDP through
              Network Address Translations (NATs)", RFC 4380,
              February 2006.

7.2.  Informative References

   [RFC2772]  Rockell, R. and B. Fink, "6Bone Backbone Routing
              Guidelines", RFC 2772, February 2000.

   [RFC3701]  Fink, R. and R. Hinden, "6bone (IPv6 Testing Address
              Allocation) Phaseout", RFC 3701, March 2004.

   [RFC3704]  Baker, F. and P. Savola, "Ingress Filtering for Multihomed
              Networks", BCP 84, RFC 3704, March 2004.

   [RFC3964]  Savola, P. and C. Patel, "Security Considerations for
              6to4", RFC 3964, December 2004.


Author's Address

   Marc Blanchet
   Viagenie

   Email: Marc.Blanchet@viagenie.ca










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Acknowledgment

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   Administrative Support Activity (IASA).





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