Caveats

To change X3 to another mode when X2 unnumbered to X3 is configured, first terminate the relationship with X2 by changing X2 to another mode. Otherwise, if you change the IP address or mask of interface X3, it causes X3 to reconnect to the PPPoE server.

If X3 is set as unnumbered interface, other interfaces cannot connect to X3 using an L2 Bridge.