Alcatel-Lucent 6850-48 Network Guide

Configuring IPv6

IPv6 Overview

OmniSwitch AOS Release 6 Network Configuration Guide

page 26-11

In the above diagram:

1 The 6to4 hosts receive 6to4 prefix from Router Advertisement.

2 The 6to4 host sends IPv6 packets to 6to4 border router.

3 The 6to4 border router encapsulates IPv6 packets with IPv4 headers and sends to the destination 6to4 
border router over the IPv4 domain.

4 The destination 6to4 border router strips IPv4 header and forwards to 6to4 destination host.

In this scenario, 6to4 sites have connectivity to native IPv6 domains through a relay router, which is 
connected to both the IPv4 and IPv6 domains. The 6to4 border routers are still used by 6to4 sites for 
encapsulating/decapsulating host traffic and providing connectivity across the IPv4 domain. In addition, 
each border router has a default IPv6 route pointing to the relay router.

In essence, a relay router is a 6to4 border router on which a 6to4 tunnel interface is configured. However, 
a native IPv6 router interface is also required on the relay router to transmit 6to4 traffic to/from IPv6 hosts 
connected to an IPv6 domain. Therefore, the relay router participates in both the IPv4 and IPv6 routing 
domains.

The following diagram illustrates the basic traffic flow between native IPv6 hosts and 6to4 sites:

In the above diagram:

1 The 6to4 relay router advertises a route to 2002::/16 on its IPv6 router interface.

2 The IPv6 host traffic received by the relay router that has a next hop address that matches 2002::/16 is 
routed to the 6to4 tunnel interface configured on the relay router.