Transition Mechanisms for IPv6 Hosts and Routers
RFC 1933
| Document | Type |
RFC - Proposed Standard
(April 1996; No errata)
Obsoleted by RFC 2893
|
|
|---|---|---|---|
| Last updated | 2013-03-02 | ||
| Stream | IETF | ||
| Formats | plain text html pdf htmlized bibtex | ||
| Stream | WG state | (None) | |
| Document shepherd | No shepherd assigned | ||
| IESG | IESG state | RFC 1933 (Proposed Standard) | |
| Consensus Boilerplate | Unknown | ||
| Telechat date | |||
| Responsible AD | (None) | ||
| Send notices to | (None) | ||
Network Working Group R. Gilligan
Request for Comments: 1933 E. Nordmark
Category: Standards Track Sun Microsystems, Inc.
April 1996
Transition Mechanisms for IPv6 Hosts and Routers
Status of this Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Abstract
This document specifies IPv4 compatibility mechanisms that can be
implemented by IPv6 hosts and routers. These mechanisms include
providing complete implementations of both versions of the Internet
Protocol (IPv4 and IPv6), and tunneling IPv6 packets over IPv4
routing infrastructures. They are designed to allow IPv6 nodes to
maintain complete compatibility with IPv4, which should greatly
simplify the deployment of IPv6 in the Internet, and facilitate the
eventual transition of the entire Internet to IPv6.
1. Introduction
The key to a successful IPv6 transition is compatibility with the
large installed base of IPv4 hosts and routers. Maintaining
compatibility with IPv4 while deploying IPv6 will streamline the task
of transitioning the Internet to IPv6. This specification defines a
set of mechanisms that IPv6 hosts and routers may implement in order
to be compatible with IPv4 hosts and routers.
The mechanisms in this document are designed to be employed by IPv6
hosts and routers that need to interoperate with IPv4 hosts and
utilize IPv4 routing infrastructures. We expect that most nodes in
the Internet will need such compatibility for a long time to come,
and perhaps even indefinitely.
However, IPv6 may be used in some environments where interoperability
with IPv4 is not required. IPv6 nodes that are designed to be used
in such environments need not use or even implement these mechanisms.
The mechanisms specified here include:
Gilligan & Nordmark Standards Track [Page 1]
RFC 1933 IPv6 Transition Mechanisms April 1996
- Dual IP layer. Providing complete support for both IPv4 and
IPv6 in hosts and routers.
- IPv6 over IPv4 tunneling. Encapsulating IPv6 packets within
IPv4 headers to carry them over IPv4 routing infrastructures.
Two types of tunneling are employed: configured and automatic.
Additional transition and compatibility mechanisms may be developed
in the future. These will be specified in other documents.
1.2. Terminology
The following terms are used in this document:
Types of Nodes
IPv4-only node:
A host or router that implements only IPv4. An
IPv4-only node does not understand IPv6. The installed
base of IPv4 hosts and routers existing before the
transition begins are IPv4-only nodes.
IPv6/IPv4 node:
A host or router that implements both IPv4 and IPv6.
IPv6-only node:
A host or router that implements IPv6, and does not
implement IPv4. The operation of IPv6-only nodes is not
addressed here.
IPv6 node:
Any host or router that implements IPv6. IPv6/IPv4 and
IPv6-only nodes are both IPv6 nodes.
IPv4 node:
Any host or router that implements IPv4. IPv6/IPv4 and
IPv4-only nodes are both IPv4 nodes.
Gilligan & Nordmark Standards Track [Page 2]
RFC 1933 IPv6 Transition Mechanisms April 1996
Types of IPv6 Addresses
IPv4-compatible IPv6 address:
An IPv6 address, assigned to an IPv6/IPv4 node, which
bears the high-order 96-bit prefix 0:0:0:0:0:0, and an
IPv4 address in the low-order 32-bits. IPv4-compatible
addresses are used by the automatic tunneling mechanism.
IPv6-only address:
The remainder of the IPv6 address space. An IPv6
address that bears a prefix other than 0:0:0:0:0:0.
Techniques Used in the Transition
IPv6-over-IPv4 tunneling:
The technique of encapsulating IPv6 packets within IPv4
so that they can be carried across IPv4 routing
infrastructures.
IPv6-in-IPv4 encapsulation:
IPv6-over-IPv4 tunneling.
Configured tunneling:
IPv6-over-IPv4 tunneling where the IPv4 tunnel endpoint
address is determined by configuration information on
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