The physical media used to transmit data in a networked environment. There are four major types of transmission media commonly in use today. These are:
- Coaxial cable - Somewhat expensive, lower bandwidth, higher resistance to electromagnetic interference, easy to splice. Coaxial cable is used
primarily in legacy networks and in cable television/cable modem networks.
- Twisted pair cable - Inexpensive, bandwidth up to 1GB currently supported, low resistance to electromagnetic interference, relatively easy to splice. Very common in Ethernet applications as well as for voice communications (telephone).
- Fiber-optic cable - Very expensive, high bandwidth, immune to electromagnetic interference, very difficult to splice. Fiber optic cable is often used for network or Internet backbones, or in locations with extreme electromagnetic activity.
- Wireless - Inexpensive, bandwidth up to 54MB currently supported, low resistance to electromagnetic interference, very easy for signal to be intercepted as it is broadcast over open air. This media is becoming very common, especially with laptop computers and handheld devices.
On the OSI reference model, transmission media would operate at Layer 1, the Physical layer.
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