The packet is then sent into the network, which makes copies of the packet and sends a copy to every node on the network. LAN Topologies LAN topologies define the manner in which network devices are organized. These topologies are logical architectures, but the actual devices need not be physically organized in these configurations. Logical bus and ring topologies, for example, are commonly organized physically as a star. A bus topology is a linear LAN architecture in which transmissions from network stations propagate the length of the medium and are received by all other stations.
Some networks implement a local bus topology.
A ring topology is a LAN architecture that consists of a series of devices connected to one another by unidirectional transmission links to form a single closed loop. Figure 2-4 depicts a logical ring topology. A star topology is a LAN architecture in which the endpoints on a network are connected to a common central hub, or switch, by dedicated links. Logical bus and ring topologies are often implemented physically in a star topology, which is illustrated in Figure 2-5 . A tree topology is a LAN architecture that is identical to the bus topology, except that branches with multiple nodes are possible in this case.