Switched Traffic vs Routed Traffic [Basics]
When a computer has a packet to send it knows the destination IP address where it wants to send the traffic. But the computer must also make sure to add a destination MAC address to the traffic which points to the next hop router. This is how the computer makes sure that the packet will end up at its default gateway (via ARP usually)
When the router receives the packet it will look at the destination IP address of the packet. Based on that destination IP address the router will know which way to forward the packet and which the next hop router will be.
Then it can strip off the old destination MAC address (which was the router’s own MAC address) and replace it with a new destination MAC address that points to the next hop router.
In simple words, the Destination MAC changes for each Hop. the router overrides the destination MAC address with the resolved Next hop (via ARP) for the routed traffic based on the destination IP.
The switches do not deliver packets based on the destination IP address. Instead, the switches look at the destination MAC address to see where it should send the packet next.
The switched traffic destination MAC address doesn’t change, the switch will only make a switching decision based on the MAC address table (MAC to port).