Page 75 - M. Abrahim Thesis

Computer Network 2021

Figure 3-20 shown a Collision Phenomena

Collision domains are the connected physical network segments where collisions can
occur. Collisions cause the network to be inefficient. Every time there is a collision on a network,
all transmission stops for a period of time. This time is variable, as determined by a back-off
algorithm for each network device, which is necessary to allow broadcast transmission to
resume. Except for a single isolated Ethernet LAN environment, the types of devices that
interconnect the media segments define collision domains.

These devices have been classified as OSI Layers 1, 2, or 3 devices. Layer 1 devices do not
break up collision domains; Layers 2 and 3 devices do break up collision domains, as described
in Figure 3-21. Breaking up or increasing the number of collision domains with Layer 2 and 3
devices is known as segmentation.

Figure 3-21 shown a Collision Domain Segmentation

Layer 1 devices, such as repeaters and hubs, serve the primary function of extending the
Ethernet cable segments. By extending the network, more hosts can be added. However, every

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