About Fast Ethernet
As the demand for desktop video, multimedia development, imaging, and other speed-intensive applications continues to rise, the need for high per- formance, fault tolerant LAN technology will become more critical.
Standard Ethernet, which has been the most popular networking technolo- gy to date with a maximum data throughput of 10 Mbps, is becoming insufficient to handle the latest video, multimedia, and other speed-inten- sive client/server LAN applications.
Among the proposed solutions to the dilemma of network speed, Fast Ethernet has emerged as the most viable and economical. Capable of send- ing and receiving data at 100 Mbps (megabits per second), it is more than fast enough to handle even the most demanding video and other real-time applications.
Although there are a number of different competing Fast Ethernet imple- mentations, 100BaseTX is by far the most popular. Operating on two pairs of Category 5 unshielded twisted-pair (UTP) cabling, 100BaseTX supports high speed signaling and is relatively inexpensive. Because it uses four wires for data transmission and the same packet format, packet length, error control, and management information as 10BaseT, 100BaseTX can be made to communicate with older 10BaseT equipment when routed through a switch.
This scalability is one of 100BaseTX's major advantages over other forms of Fast Ethernet: it allows critical, speed-dependent network segments to be upgraded to 100BaseTX speeds as needed without rewiring, refitting, and retraining an entire site. Heterogeneous networks can now mix both slow and fast network segments for different users or for different depart- ments. Publishing, R&D, video, multimedia, or accounting departments can enjoy a 100Mbps pace, while other corporate segments can operate at slower and more economic 10Mbps speeds.
A network without a switch is often called a shared-bandwidth network because the net's overall bandwidth is shared among all of the nodes – each PC, file server, or other node gets a piece of the bandwidth. In a shared network, data packets are sent to all available nodes until they fall upon their destination. Much of the bandwidth, consequently, is wasted because some packets have to spend time "looking" for their destinations.