Logical Topologies
The logical topology of a network refers to the logical paths that the signals use to travel from one point on the network to anotherthat is, the way in which data accesses the network media and transmits packets across it.
The physical and logical topologies of a network can be the same. For example, in a network physically shaped as a linear bus, the data travels along the length of the cable. Therefore, the network has both a physical bus topology and a logical bus topology.
On the other hand, a network can have quite different physical and logical topologies. For example, a physical topology in the shape of a star, in which cable segments connect all computers to a central hub, can have a logical ring topology. Remember that in a ring, the data travels from one computer to the next, and inside the hub, the wiring connections are such that the signal actually travels around in a circle from one port to the next, creating a logical ring. Therefore, you cannot always predict how data travels in a network simply by observing its physical layout.
Star topology is by far the most common implementation of LANs today. Ethernet uses a logical bus topology in either a physical bus or a physical star. An Ethernet hub is an example of a physical star topology with a logical bus topology.
Figure 1-6 Common Physical Topologies
Bus Topology
Ring Topology
Star Topology
Bus Topology
Ring Topology
Star Topology
Figure 1-7 shows some common logical topologies used in networking.
Figure 1-7 Common Logical Topologies
Server
Figure 1-7 Common Logical Topologies
Server
Continue reading here: Bus Topology
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