Network Technology

In this section, we will look at the various technologies available to implement your network. The primary concern here is to give you a full understanding of the possibilities so that you can design your network to fulfill your real-world requirements. Keep in mind that network technology is a rapidly changing environment, which means, the fastest technology today may not be the fastest tomorrow. It pays to plan ahead here to pave the way for future technologies.

Network Cable Types

There are currently five types of network cable in use today. Each cable type is designed for a specific network configuration and has its own associated strengths and weaknesses. These cable types include:

•  Thick Ethernet—This cable type was originally introduced by Xerox as a means of connecting multiple computers on its campus network. The cable is approximately 15mm thick and is quite rigid. It is also heavily shielded to prevent electrical interference. Thick Ethernet cables are rarely used in today’s networks due to the expense involved.

•  Thin Ethernet (COAX)—This cable is almost identical to the cable used by your cable TV contractor. It has a core cable constructed of copper wire embedded in a plastic insulator that is surrounded by two layers of shielding material with a final plastic insulator. It is very inexpensive compared to thick Ethernet, but rarely used in today’s production environments.

•  Unshielded Twisted Pair (UTP)—This particular cable utilizes two pairs of wire twisted (the more twists the better the signaling capability) around each other to provide a resonant magnetic field to increase signal quality. In appearance, it looks just like your phone cable.

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Note:  There are actually five different categories of UTP cabling. Levels 1 and 2 are low-grade cables designed for voice-only transmissions. Level 3 is the minimum required level for 10Mb networks. Level 4 supports up to 16Mb networks, and Level 5 supports up to 100Mb networks. When you make the choice for your network cable, I recommend that you purchase Level 5 UTP cable, as approximately 75 percent of your installation cost is based on the labor of pulling the cables. If you choose to install Level 5 cable, it will provide the longest service life and make your network cabling Ethernet-ready if you decide to migrate to this medium later.

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•  Shielded Twisted Pair (STP)—Like UTP cable, STP cable includes two pairs of wires twisted around each other. But it differs from UTP by the shielding wrapped around each individual pair as well as the layer of shielding around both pairs. This shielding provides better signaling capabilities than UTP and should be used in electrically noisier environments.

•  Fiber Optics—This is the best cable around for electrically noisy environments because it carries pulses of light rather than electrical pulses. It should be used as the backbone of a computer network to provide the fastest and most error-free data path between servers. Like a COAX cable, a fiber-optic cable has a core, made of glass rather than copper, surrounded by several layers to protect the glass core. However, instead of a single cable used to send and receive data, you are required to use two separate fiber-optic cables—one to send data, and one to receive data.

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Another use of fiber-optic cables is to provide an electrically isolated method of joining two physical segments. For instance, rather than use electrical cables to span two segments in different buildings, use a pair of fiber-optic cables. That way, you have isolated the two networks from electrical interference rather than joining the two networks with a lightning rod. I’ve actually seen the results of a lightning strike that destroyed several network servers connected with wire rather than fiber. After this incident, when the new hardware was installed, the choice for network connection between these two buildings was fiber-optic cables.

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