Configuration guidelines
Follow these guidelines when you configure an IPv4 over IPv4 tunnel:
The tunnel source end and destination end must be public addresses or interfaces.
To encapsulate and forward IPv4 packets whose destination address does not belong to the subnet where the receiving tunnel interface resides, configure a static route or dynamic routing for forwarding those packets through this tunnel interface. If you configure a static route to that destination IPv4 address, specify 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. If you configure dynamic routing at both ends, enable the dynamic routing protocol on both tunnel interfaces. For the detailed configuration, see Layer 3—IP Routing Configuration Guide.
The IPv4 address of the local tunnel interface cannot be on the same subnet as the destination address of the tunnel.
The destination address of a route with a tunnel interface as the egress interface must not be on the same subnet as the destination address of the tunnel.
Two or more tunnel interfaces using the same encapsulation protocol must have different source and destination addresses.
If you specify a source interface instead of a source address for the tunnel, the source address of the tunnel is the primary IP address of the source interface.