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Understand that every type of network has both a physical and a logical topology. The physical topology of a network refers to the physical layout of the devices, but mostly the cabling and cabling layout. The logical topology defines the logical path on which the signal will travel on the physical topology. Figure 1.11 shows the four types of topologies:

Figure 1.11 Physical vs. Logical Topolgies

Here are the topology types, although the most common, and pretty much only network we use today is a physical star, logical bus technology, which is considered a hybrid topology (think Ethernet):

■ Bus: In a bus topology, every workstation is connected to a single cable, meaning every host is directly connected to every other workstation in the network.

■ Ring: In a ring topology, computers and other network devices are cabled together in a way that the last device is connected to the first to form a circle or ring.

■ Star: The most common physical topology is a star topology, which is your Ethernet switching physical layout. A central cabling device (switch) connects the computers and other network devices together. This category includes star and extended star topologies. Physical connection is commonly made using twisted-pair wiring.

■ Mesh: In a mesh topology, every network device is cabled together with a connection to each other. Redundant links increase reliability and self-healing. The physical connection is commonly made using fiber or twisted-pair wiring.

■ Hybrid: Ethernet uses a physical star layout (cables come from all directions), and the signal travels end-to-end, like a bus route.

Exam Essentials

Describe the major physical topologies in use. Identify the differences between a physical and logical topology. List the distinguishing features of the star, ring, bus, mesh, and hybrid topologies