What four functions does a router perform at each hop along the path when forwarding frames?

Accept the frame, de-encapsulate it to expose the packet, re-encapsulate the packet into a new frame, then forward it on the next segment.

A router connects different network segments that may use different media (Ethernet, fiber, serial WAN) and therefore different Layer 2 frame formats. It cannot simply pass a frame through, because the frame is only meaningful on the link it arrived on. So at every hop the router strips off the incoming Layer 2 header to recover the original Layer 3 packet, then wraps that same packet in a brand-new frame built for the outgoing link. The Layer 3 packet (and its IP addresses) stays unchanged end to end, while the Layer 2 frame is rebuilt at each hop — which is why a packet can cross many different media types on its journey.

* At each hop the L2 frame is rebuilt while the L3 packet rides through unchanged. *

At each hop, a router performs these four Layer 2 functions:

1. Accepts a frame from the network medium
2. De-encapsulates the frame to expose the encapsulated packet
3. Re-encapsulates the packet into a new frame
4. Forwards the new frame on the medium of the next network segment

Key insight: Packets may experience numerous data link layers and media transitions as they travel across a network. The Layer 2 header changes at each hop, but the Layer 3 packet remains the same.

Go deeper:

• Host to Host through a Router (Practical Networking) — walks through accept → de-encapsulate → re-encapsulate → forward, showing the L2 frame regenerated each hop while the IP header stays identical.
• Data Link Layer (NetworkAcademy.IO CCNA) — reinforces it from a CCNA angle: MAC addresses change per hop, IP addresses stay constant, FCS recomputed.