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IPv6 Overview Configuring IPv6
page 15-8 OmniSwitch 6600 Family Network Configuration Guide April 2006
6to4 Site to 6to4 Site over IPv4 Domain
In this scenario, isolated IPv6 sites have connectivity over an IPv4 network through 6to4 border routers.
An IPv6 6to4 tunnel interface is configured on each border router and assigned an IPv6 address with the
6to4 well-known prefix, as described above. IPv6 hosts serviced by the 6to4 border router have at least
one IPv6 router interface configured with a 6to4 address. Note that additional IPv6 interfaces or external
IPv6 routing protocols are not required on the 6to4 border router.
The following diagram illustrates the basic traffic flow between IPv6 hosts communicating over an IPv4
domain:
In the above diagram:
1 6to4 hosts receive 6to4 prefix from Router Advertisement.
2 6to4 host sends IPv6 packets to 6to4 border router.
3 6to4 border router encapsulates IPv6 packets with IPv4 headers and sends to destination 6to4 border
router over the IPv4 domain.
4 Destination 6to4 border router strips IPv4 header and forwards to 6to4 destination host.
6to4 Site to IPv6 Site over IPv4/IPv6 Domains
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. 6to4 border routers are still used by 6to4 sites for encapsu-
lating/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 in that a 6to4 tunnel interface is configured on the router.
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:
6to4 Site
IPv4 Domain
6to4 Host
6to4 Host
6to4 Site
IPv6 6to4
Border Router
IPv6 6to4
Border Router