|  | 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