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standard, designed to raise the data transmission capacity of 10Base-T from 10Mbits/sec to
100Mbits/sec. An important technology incorporated by 100Base-T is its use of the Carrier Sense
Multiple Access with Collision Detection (CSMA/CD) protocol, which is the same protocol that
10Base-T uses, because of its ability to work with several different types of cable, including basic
twisted-pair wiring. Both of these features play an important role in network considerations, and
they make 100Base-T an attractive migration path for those networks based on 10Base-T. Since
the 100Mbps Fast Ethernet is compatible with all other 10Mbps Ethernet environments, it provides
a straightforward upgrade and takes advantage of the existing investment in hardware, software,
and personnel training.
1.3 Switching Technology
Switching is a cost-effective way of increasing the total network capacity available to users on a
LAN. If an Ethernet network begins to display symptoms of congestion, low throughput, slow
response times, and high rates of collision, installing a switch to a network can preserve much or
all of the existing network's cabling and workstation interface card infrastructure while still greatly
enhancing the throughput for users. A switch is a viable solution even if demanding applications,
such as multimedia production and video conferencing, are on the horizon. The most promising
techniques, as well as the best return on investment, could well consist of installing the right
mixture of Ethernet switches.
A switch increases capacity and decreases network loading by dividing a local area network into
different LAN segments. Dividing a LAN into multiple segments is one of the most common ways
of increasing available bandwidth. If segmented correctly, most network traffic will remain within a
single segment, enjoying the full-line speed bandwidth of that segment. Switches provide full-line
speed and dedicated bandwidth for all connections. This is in contrast to hubs, which use the
traditional shared networking topology, where the connected nodes contend for the same network
bandwidth. When two switching nodes are communicating, they are connected with a dedicated
channel between them, so there is no contention for network bandwidth with other nodes. As a
result, the switch reduces considerably the likelihood of traffic congestion. For Fast Ethernet
networks, a switch is an effective way of eliminating the problem of chaining hubs beyond the “two-
repeater limit.” A switch can be used to split parts of the network into different collision domains,
making it possible to expand your Fast Ethernet network beyond the 205-meter network diameter
limit for 100BASE-TX networks. Switches supporting both traditional 10Mbps Ethernet and
100Mbps Fast Ethernet are also ideal for bridging between existing 10Mbps networks and new
100Mbps networks. Switching LAN technology is a marked improvement over the previous
generation of network hubs and bridges, which were characterized by higher latencies. Routers
have also been used to segment local area networks, but the cost of a router, and the setup and
maintenance required make routers relatively impractical. Today switches are an ideal solution to
most kinds of local area network congestion problems.
1.4 Key Features
