What happens with link layer LAN Ethernet header data once the once the frame reaches the main home router and is forwarded to the first network core router?
Routers are network layer devices and forward based on the IP destination address. Local network switches forward based on MAC address in frame headers. To get the frame to the home router, router MAC address is placed in frame header originating at the host, but getting the frame from home router to the next one in WAN, the MAC address plays no role, since this is done based on IP.
So, what happens with MAC address once the frame reaches the home router and is forward to the next one? Is is deleted? Are there protocols to discover the MAC address of the next router (like ARP in the local network); is MAC address of the next router even needed?