Both coaxial and twisted pair cables serve as a basic connection medium for network cabling. Information transmitted across wired computer networks and through computer network nodes travels through network cables and passes from the cables to the network nodes through special connectors. Each type of cable has a specific design that promotes the integrity of data transmission and reduces the potential for signal interference, with the different designs reflecting different basic approaches to achieving the same goal.
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A network can be composed of both coaxial cable and twisted pair cable so that one section of the network uses coaxial cable and a different section uses twisted pair cable. Each type of cable has specific properties that can make it better suited for use under different conditions. A network's size, both in terms of the physical distance over which the network extends and in terms of the number of devices attached to the network, can influence the choice of one type of cable over the other.
Coaxial cable, sometimes referred to as coax, has four internal layers. At the core is an inner conductor. An insulating layer covers the inner conductor, and a second conductive layer in turn covers the inner insulating layer. The final layer is a thin insulating layer that is the visible, outer layer of the cable. Coaxial cable is generally less expensive than twisted pair cable. Coaxial cable is seldom used in computer networks anymore, but is widely used for cable television services and video connections, like those used by closed circuit surveillance systems.
Twisted pair cabling comes in two varieties: shielded and unshielded. The design common to both varieties is two conductors twisted around each other, with one conductor serving as the forward circuit and the other as the return circuit. Unshielded twisted pair cable (UTP) is less expensive than shielded twisted pair (STP) cable. However, the lack of shielding around UTP cable makes it more susceptible to interference from electronic devices.
Coaxial cabling connects to network devices through BNC connectors. These connectors can take configurations such as simple male/female connectors, T-connectors that enable three separate cables to be connected or as terminal connectors. By contrast, twisted pair cables generally connect through RJ connectors, like the RJ-45 connectors used on Ethernet networks and the smaller RJ-11 connector used with telephone cables.
Strengths And Weaknesses
Both coaxial cable and twisted pair cable can support network speeds in both the megabit and gigabit ranges. Both are susceptible in varying degrees to signal interference, where external signals interfere with transmission inside the cable, and signal leakage, where signals inside the cable leak out and become a source of interference to other devices. Coaxial cable, being of a standard design, varies little in its susceptibility to interference. For twisted pair cable, however, the cables resistance to interference depends in large part on the degree to which the twisting scheme remains in place, and therefore can vary widely.