Page 48 - M. Abrahim Thesis

Chapter (2) Network Fundamental and Layered Network Architecture

electrical signal representing the data bounces back at the end of the wire, causing errors in the
network. https://www.youtube.com/watch?v=dMUOQj4AwB0

2.10.1.2 Star and Extended-Star Topologies

The star topology, shown in Figure below, is the most commonly used physical topology
in Ethernet LANs. When installed, the star topology resembles spokes in a bicycle wheel. The
star topology is made up of a central connection point that is a device such as a hub, switch, or
router, where all the cabling segments meet. Each host in the network is connected to the
central device with its own cable.

Although a physical star topology costs more to implement than the physical bus
topology, the advantages of a star topology make it worth the additional cost. Because each host
is connected to the central device with its own cable, when that cable has a problem, only that
host is affected; the rest of the network remains operational.
This benefit is extremely important and is why virtually every newly designed Ethernet
LAN has a physical star topology. A central connection point might be desirable for security or
restricted access, but this is also a main disadvantage of a star topology. If the central device
fails, the whole network becomes disconnected, s shown in Figure 2-22.

Figure 2-22 shown a Star Topology of Network Devices

When a star network is expanded to include an additional networking device that is
connected to the main networking device, it is called an extended-star topology, as shown in
Figure 2-23.

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