RFC 2185 (rfc2185) - Page 2 of 13

Routing Aspects of IPv6 Transition

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