Figure 2-3 shows how a switch
has been used to isolate each user and device into its own collision domain.
Figure 2-3 Creating Multiple Collision Domains Using a Switch
Collision
Domain 4
Collision
Domain 3
Collision
Domain 2
Collision
Domain 1
144 Chapter 2: Ethernet LANs
Summary of Ethernet Local-Area Networks
The key points that were discussed in the previous sections are as follows:
?– A segment is a network connection made by a single unbroken network cable. Ethernet
cables and segments can only span a limited physical distance, after which the
transmissions become degraded.
?– A hub works like a multiport repeater and can effectively extend a network segment
by receiving the incoming frames, amplifying the electrical signals, and transmitting
these frames back out through all ports to all devices that are connected to segments on
the same Ethernet hub.
?– If two or more stations connected to the same hub transmit at the same time, a collision
results because of the half-duplex nature of the Ethernet 802.3 CSMA/CD
speci?¬?cation.
?– The network segments that share the same bandwidth are called collision domains
because when two or more devices on the same segment both communicate and send
data at the same time, collisions can occur within that shared segment.
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