The ability to link a wide range of computers using a vendor-neutral network technology is an essential feature for today's LAN managers. Most LANs must support a wide variety of computers purchased from different vendors, which requires a high degree of network interoperability of the sort that Ethernet provides. Each Ethernet-equipped computer, also known as a station, operates independently of all other stations on the network: there is no central controller. All stations attached to an Ethernet are connected to a shared.
signaling system, also called the medium. Ethernet signals are transmitted serially, one bit at a time, over the shared signal channel to every attached station. .
To send data a station first listens to the channel, and when the channel is idle the station transmits its data in the form of an Ethernet frame, or packet. .
After each frame transmission, all stations on the network must contend equally for the next frame transmission opportunity. This ensures that access to the network channel is fair, and that no single station can lock out the other stations. Access to the shared channel is determined by the medium access control (MAC) mechanism embedded in the Ethernet interface located in each station. The medium access control mechanism is based on a system called Carrier Sense Multiple Access with Collision Detection (CSMA/CD). .
Thick coaxial segments are still sometimes installed as a backbone segment for interconnecting Ethernet hubs, since thick coaxial media provides a low-cost cable with good electrical shielding that can carry signals relatively long distances between hubs. On the other hand, thick coaxial cable is limited to carrying 10-Mbps signals only, which means you must replace the cable if you wish to link hubs together at higher speeds. High quality twisted-pair cable or fiber optic cable can carry either 10-Mbps or 100-Mbps signals, therefore many sites prefer to use these cables as a way of linking hubs together.