there was a leased line 256kbps connecting two remote sites with serial interfaces. Today the leased line replaced with a fiber optic cable. the one serial interface remains on the side and the other side the Fiber ending into a switch converted to copper.
If we connect that ethernet cable into a routers ethernet interface is there any problem , is there any need of encapsulation protocol?that router leads to internet .
You can easily replace the serial interface with the ethernet interface which gives u the option of upgrade in a fly.
You really dont need to change any encapsulation...