Transmitting Packets to Remote Segments
Remember, when TCP/IP hosts transmit a packet to a remote segment, they cannot use ARP because routers filter broadcasts.
Instead, TCP/IP hosts transmitting packets to remote segments contact their default gateway, which is the network interface on a router.
The TCP/IP host sends the data packet with the destination MAC address of the router. However, since the ultimate destination for the packet is a client on a remote network, the destination IP address is the address of the remote host.
When the router receives the packet, it pulls off the Network Interface (OSI layer 2) information and analyzes the packet at the Internetwork (OSI layer 3) layer.