You want to configure a router to act as a gateway between IPv4 and IPv6 networks.
Cisco includes a protocol translation feature that allows you to interconnect IPv6 and IPv4 networks:
configure terminalEnter configuration commands, one per line. End with CNTL/Z. Router1(config)#
permit ipv6 any anyRouter1(config-ipv6-acl)#
ipv6 nat prefix
ipv6 nat v6v4 source
no ip addressRouter1(config-if)#
Starting in IOS Version 12.2(13)T, Cisco introduced the ability to use a router as a protocol gateway, translating between IPv6 and IPv4 worlds by means of Network Address Translation with Protocol Translation (NAT-PT). For more information on NAT in general, please refer to Chapter 21.
RFCs 4038 and 4291 include discussions of how to address IPv4 packets that originate in an IPv6 network. The current standard method is called the “IPv4-Mapped IPv6 Address,” which works very simply. If an IPv6 device wants to send a packet to an IPv4 device whose address ...