Routing Aspects of IPv6 Transition
RFC 2185
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RFC - Informational
(September 1997; No errata)
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Authors |
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Dimitry Haskin
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Ross Callon
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Last updated |
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2013-03-02
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IETF
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plain text
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(None)
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No shepherd assigned
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IESG |
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RFC 2185 (Informational)
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Unknown
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Network Working Group R. Callon
Request for Comments: 2185 Cascade Communications Co.
Category: Informational D. Haskin
Bay Networks Inc.
September 1997
Routing Aspects Of IPv6 Transition
Status of this memo
This memo provides information for the Internet community. This memo
does not specify an Internet standard of any kind. Distribution of
this memo is unlimited.
Abstract
This document gives an overview of the routing aspects of the IPv6
transition. It is based on the protocols defined in the document
"Transition Mechanisms for IPv6 Hosts and Routers" [1]. Readers
should be familiar with the transition mechanisms before reading this
document.
The proposals contained in this document are based on the work of the
Ngtrans working group.
1. TERMINOLOGY
This paper uses the following terminology:
node - a protocol module that implements IPv4 or IPv6.
router - a node that forwards packets not explicitly
addressed to itself.
host - any node that is not a router.
border router - a router that forwards packets across
routing domain boundaries.
link - a communication facility or medium over which
nodes can communicate at the link layer, i.e., the layer
immediately below internet layer.
interface - a node's attachment to a link.
address - an network layer identifier for an interface or
a group of interfaces.
Callon & Haskin Informational [Page 1]
RFC 2185 Routing Aspects Of IPv6 Transition September 1997
neighbors - nodes attached to the same link.
routing domain - a collection of routers which coordinate
routing knowledge using a single routing protocol.
routing region (or just "region") - a collection of routers
interconnected by a single internet protocol (e.g. IPv6)
and coordinating their routing knowledge using routing
protocols from a single internet protocol stack. A
routing region may be a superset of a routing domain.
tunneling - encapsulation of protocol A within protocol B,
such that A treats B as though it were a datalink layer.
reachability information - information describing the set of
reachable destinations that can be used for packet
forwarding decisions.
routing information - same as reachability information.
address prefix - the high-order bits in an address.
routing prefix - address prefix that expresses destinations
which have addresses with the matching address prefixes.
It is used by routers to advertise what systems they are
capable of reaching.
route leaking - advertisement of network layer reachability
information across routing region boundaries.
2. ISSUES AND OUTLINE
This document gives an overview of the routing aspects of IPv4 to
IPv6 transition. The approach outlined here is designed to be
compatible with the existing mechanisms for IPv6 transition [1].
During an extended IPv4-to-IPv6 transition period, IPv6-based systems
must coexist with the installed base of IPv4 systems. In such a dual
internetworking protocol environment, both IPv4 and IPv6 routing
infrastructure will be present. Initially, deployed IPv6-capable
domains might not be globally interconnected via IPv6-capable
internet infrastructure and therefore may need to communicate across
IPv4-only routing regions. In order to achieve dynamic routing in
such a mixed environment, there need to be mechanisms to globally
distribute IPv6 network layer reachability information between
dispersed IPv6 routing regions. The same techniques can be used in
later stages of IPv4-to-IPv6 transition to route IPv4 packets between
isolated IPv4-only routing region over IPv6 infrastructure.
Callon & Haskin Informational [Page 2]
RFC 2185 Routing Aspects Of IPv6 Transition September 1997
The IPng transition provides a dual-IP-layer transition, augmented by
use of encapsulation where necessary and appropriate. Routing issues
related to this transition include:
(1) Routing for IPv4 packets
(2) Routing for IPv6 packets
(2a) IPv6 packets with IPv6-native addresses
(2b) IPv6 packets with IPv4-compatible addresses
(3) Operation of manually configured static tunnels
(4) Operation of automatic encapsulation
(4a) Locating encapsulators
(4b) Ensuring that routing is consist with
encapsulation
Basic mechanisms required to accomplish these goals include: (i)
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