The State of Hawaii Department of Education defines a LAN as a network of computers in a school. A router is hardware that allows messages to be sent between two or more networks. Like a bridge, a router has its own microprocessor and knows where the workstations are located, however, a router has more software intelligence than a bridge and is more suited for complex environments or large internetworks. Messages sent in a network are broken into manageable chunks called packets. The packet size is controlled by the Network Layer and is identical on both sides.
End nodes send packets directly to the router.
The router reads the destination code that tells where the packets are intended. The router is able to consider and select one of the many different possible paths available to forward the packets. A routing decision is based on the destination node's network-layer address and other factors such as the shortest path to the node, transit delay, congestion at other routers, and the number of routers between the source and destination stations. Once a decision has been made, a new destination code is established. The destination address, which remains constant, and the address of the next node along the route.