Network Components Flashcards
Media:
Devices need to be interconnected via some sort of media. This media could be copper cabling. Alternatively, it could be a fiber-optic cable. Media might not even be a cable, as is the case with wireless networks, where radio waves travel through the media of air.
Coaxial Cable:
Coaxial cable (referred to as coax) consists of two conductors. One of the conductors is an inner insulated conductor. This inner conductor is surrounded by another conductor. This second conductor is sometimes made of metallic foil or woven wire. Because the inner conductor is shielded by the metallic out conductor, coaxial cable is resistant to electromagnetic interference (EMI). Coaxial Cables have an associated characteristic impedance that needs to be balanced with the device (or terminator) with which the cable connects. Coaxial cable’s role in modern computer networks is as the media used by cable modems.
Electromagnetic Interference (EMI) or Radio Frequency Interference (RFI)
EMI occurs when an external signal is received on a wire and might result in a corrupted data transmission. As another example, EMI occurs when a wire acts as an antenna and radiates electromagnetic waves, which might interfere with data transmission on another cable.
Coaxial Cable: RG-59
Radio Guide (RG)
typically used for short-distance applications, such as carrying composite video between two nearby devices. This cable type has loss characteristics such that it is not right for long-distance applications. RG-59 cable has a characteristic impedance of 75 ohms.
Coaxial Cable: RG-6
Radio Guide (RG)
Used by local cable companies to connect individual homes to the cable company’s distribution network. Like RG-59 cable, RG-6 cable has a characteristic impedance of 75 ohms.
Coaxial Cable: RG-58
Radio Guide (RG)
Has loss characteristics and distance limitations like those of RG-59. However, the characteristic impedance of RG-58 is 50 ohms, and this type of coax was popular with early 10BASE2 Ethernet networks.
