RFC 3056 (rfc3056) - Page 2 of 23

Connection of IPv6 Domains via IPv4 Clouds

RFC 3056       Connection of IPv6 Domains via IPv4 Clouds  February 2001


Table of Contents

   1. Introduction................................................. 2
   1.1. Terminology................................................ 4
   2. IPv6 Prefix Allocation....................................... 5
   2.1 Address Selection........................................... 6
   3. Encapsulation in IPv4........................................ 6
   3.1. Link-Local Address and NUD................................. 7
   4. Maximum Transmission Unit.................................... 7
   5. Unicast scenarios, scaling, and transition to normal prefixes 8
   5.1 Simple scenario - all sites work the same................... 8
   5.2 Mixed scenario with relay to native IPv6...................  9
   5.2.1 Variant scenario with ISP relay.......................... 12
   5.2.2 Summary of relay router configuration.................... 12
   5.2.2.1. BGP4+ not used........................................ 12
   5.2.2.2. BGP4+ used............................................ 12
   5.2.2.3. Relay router scaling.................................. 13
   5.2.3 Unwilling to relay....................................... 13
   5.3 Sending and decapsulation rules............................ 13
   5.4 Variant scenario with tunnel to IPv6 space................. 14
   5.5 Fragmented Scenarios....................................... 14
   5.6 Multihoming................................................ 16
   5.7 Transition Considerations.................................. 16
   5.8 Coexistence with firewall, NAT or RSIP..................... 16
   5.9 Usage within Intranets..................................... 17
   5.10 Summary of impact on routing.............................. 18
   5.11. Routing loop prevention.................................. 18
   6. Multicast and Anycast....................................... 19
   7. ICMP messages............................................... 19
   8. IANA Considerations......................................... 19
   9. Security Considerations..................................... 19
   Acknowledgements............................................... 20
   References..................................................... 20
   Authors' Addresses............................................. 22
   Intellectual Property.......................................... 22
   Full Copyright Statement....................................... 23

1. Introduction

   This memo specifies an optional interim mechanism for IPv6 sites to
   communicate with each other over the IPv4 network without explicit
   tunnel setup, and for them to communicate with native IPv6 domains
   via relay routers.  Effectively it treats the wide area IPv4 network
   as a unicast point-to-point link layer.  The mechanism is intended as
   a start-up transition tool used during the period of co-existence of
   IPv4 and IPv6.  It is not intended as a permanent solution.





Carpenter & Moore           Standards Track