Fast Ethernet Overview
Fast Ethernet Overview
The term Ethernet is commonly used for all carrier sense multiple access collision detect (CSMA/CD), LANs that generally conform to Ethernet specifications, including Fast Ethernet under IEEE 802.3u.
Note 100BaseTX is intended for Environment A, and 100BaseFX is intended for Environment B.
IEEE 802.3u is well suited to applications where a local communication medium must carry sporadic, occasionally heavy traffic at high peak data rates. Stations on a CSMA/CD LAN can access the network at any time. Before sending data, the station listens to the network to see if it is already in use. If it is, the station waits until the network is not in use, then transmits; this is
Both Ethernet and IEEE 802.3u are broadcast networks, which means that all stations see all transmissions. Each station must examine received frames to determine whether it is the intended destination and, if it is, pass the frame to a higher protocol layer for processing.
IEEE 802.3u specifies the following different physical layers for 100BaseT:
•
•
•
Each physical layer protocol has a name that summarizes its characteristics in the format
speed/signaling method/segment length, where speed is the LAN speed in Mbps, signaling method is either baseband or broadband, and segment length is typically the maximum length between stations in hundreds of meters. Therefore, 100BaseT specifies a
Overview