Configuration restrictions and guidelines
Follow these guidelines when you configure a 6to4 tunnel:
You do not need to configure a destination address for a 6to4 tunnel, because the destination IPv4 address is embedded in the 6to4 IPv6 address.
Do not specify the same source addresses for local tunnel interfaces in the same tunnel mode.
Automatic tunnels do not support dynamic routing. You must configure a static route destined for the destination IPv6 network if the destination IPv6 network is not in the same subnet as the IPv6 address of the tunnel interface. You can specify the local tunnel interface as the egress interface of the route or specify the IPv6 address of the peer tunnel interface as the next hop of the route. For more information about route configuration, see Layer 3—IP Routing Configuration Guide.