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. Routers connect two or more networks, each of which must have a unique network number in order for routing to be successful. The unique network number is incorporated into the IP address that is assigned to each device attached to that network. Example: A network has a unique network number - A. It has four devices attached to it. The IP addresses of the devices are A2, A3, A4, and A5. Since the interface where the router connects to a network is considered to be part of that network, the interface where the router connects to network A has an IP address of A1. Example: Another network, with a unique network number - B - has four devices attached to it. This network is also attached to the same router, but at a different interface. The IP addresses of the devices on this second network are B1, B2, B3, and B4. The IP address of the router's second interface is B5. Example: You want to send data from one network to another. The source network is A; the destination network is B; and a router is connected to networks A, B, C, and D. When data (frames), coming from network A, reaches the router, the router performs the following functions: 1. It strips off the data link header, carried by the frame. (The data link header contains the MAC addresses of the source and destination.) 2. It examines the network layer address to determine the destination network. 3. It consults its routing ...
