|  | 3.3 | Basics of Data Flow Through LANs
| 3.3.4 | Packet flow through Layer 3 devices

The main device that is discussed at the Network layer is the router. Routers actually operate at Layer 1 (bits on the medium at router interfaces), Layer 2 (frames switched from one interface to another), based on packet information and Layer 3 (routing decisions).

Packet flow through routers (i.e. selection of best path and actual switching to the proper output port) involves the use of Layer 3 network addresses. After the proper port has been selected, the router encapsulates the packet in a frame again to send the packet to its next destination. This process happens for every router in the path from the source host to the destination host.

| Web Links
| Encapsulation
| Packets
| Data Encapsulation
| Encapsulation Slide
| Encapsulation of PDUs