Network+

Скачать в pdf «Network+»


Connecting UTP


Clearly, a BNC connector won’t fit easily on UTP cable, so you need to use an RJ (Registered Jack) connector. You are probably familiar with RJ connectors. Most telephones connect with an RJ-11 connector.


The connector used with UTP cable is called RJ-45. The RJ-11 has four wires, or two pairs, and the network connector RJ-45 has four pairs, or eight wires, as shown in Figure 1.16.


FIGURE


. 1 6    RJ-11 and RJ-45 connectors


In almost every case, UTP uses RJ connectors. Even the now-extinct ARCnet used RJ connectors. You use a crimper to attach an RJ connector to a cable, just as you use a crimper with the BNC connector. The only difference is that the die that holds the connector is a different shape. Higher-quality crimping tools have interchangeable dies for both types of cables.

Signaling Methods


The amount of a cable’s available bandwidth (overall capacity, such as 10Mbps) that is used by each signal depends on whether the signaling method is baseband or broadband. Baseband uses the entire bandwidth of the cable for each signal (using one channel). It is typically used with digital signaling.


In broadband, multiple signals can be transmitted on the same cable simultaneously by means of frequency division multiplexing (FDM). Multiplexing is dividing a single medium into multiple channels. With FDM, the cable’s bandwidth is divided into separate channels (or frequencies), and multiple signals can traverse the cable on these frequencies simultaneously.


FDM is typically used for analog transmissions. Another method, time division multiplexing (TDM), can also be used to further divide each individual FDM frequency into individual time slots. Additionally, TDM can be used on baseband systems.

Скачать в pdf «Network+»