Configuration guidelines
Follow these guidelines when you configure a 6to4 tunnel:
Specify a public address or interface as the source address or interface for the tunnel.
No destination address needs to be configured for a 6to4 tunnel because the destination address can automatically be obtained from the IPv4 address embedded in the 6to4 IPv6 address.
To encapsulate and forward IPv6 packets whose destination address does not belong to the subnet where the receiving tunnel interface resides, configure a static route to reach the destination IPv6 address through this tunnel interface on the device. Because automatic tunnels do not support dynamic routing, you can configure a static route to that destination IPv6 address with this tunnel interface as the outbound interface or the peer tunnel interface address as the next hop. A similar configuration is required at the other tunnel end. For the detailed configuration, see Layer 3—IP Routing Configuration Guide.
Automatic tunnel interfaces using the same encapsulation protocol cannot share the same source IP address.