|  | 11.1 | Layer 3 Devices
| 11.1.2 | Layer 3 addresses
Bridges and switches use physical, or MAC addresses, to make data forwarding decisions. Routers use a Layer 3 addressing scheme to make forwarding decisions. They use IP, or logical addresses, rather than MAC addresses. Because IP addresses are implemented in software, and refer to the network on which a device is located, sometimes these Layer 3 addresses are referred to as protocol addresses, or network addresses. Physical, or MAC addresses, are usually assigned by the NIC manufacturer and are hard-coded into the NIC. The network administrator usually assigns IP addresses. In fact, it is not unusual for a network administrator to group devices together in the IP addressing scheme, according to their geographical location, department, or floor within a building. Because they are implemented in software, IP addresses are fairly easy to change. Finally, bridges and switches are primarily used to connect segments of a network. Routers are used to connect separate networks and to access the worldwide Internet. They do this by providing end-to-end routing.