Telecommunications Hardware: Routers, Modems, Switches, Bridges, and Gateways Video

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  • 0:30 Transmission Media
  • 2:27 Repeaters, Hubs,…
  • 3:55 Routers and Gateways
  • 5:39 Modems
  • 7:33 Network Interface Card
  • 8:11 Lesson Summary
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Lesson Transcript
Instructor: Paul Zandbergen

Paul has a PhD from the University of British Columbia and has taught Geographic Information Systems, statistics and computer programming for 15 years.

Building a computer network requires specialized hardware. Learn about transmission media and the variety of hardware devices needed for a computer network.

Network Hardware

Let's say you're in charge of setting up a computer network for an office building. Every desk has a computer on it, and there are also some printers and other peripheral devices sitting around. What are you going to need in terms of hardware to set up the network? You probably guessed that you're going to need some cables, but what else? Time to sit down and make a shopping list before you head out to the computer store.

Transmission Media

The first thing to consider is how you plan to transmit data across the network. The transmission media of a computer network describes the material substances that carry energy waves, which include the data being transferred. The two main categories are wired, or guided, which uses physical cables, and wireless, or unguided, which uses electromagnetic waves that can travel through a vacuum or a medium, such as air. Wireless signals do not require a physical medium, such as cables.

The most commonly used wired connections use twisted-pair cables, coaxial cables and fiber optic cables. Twisted-pair cables consist of individual copper wires that are twisted into pairs. The wires are wrapped in an insulation material. Twisted-pair cables are widely used for telephone service.

A coaxial cable consists of a copper or aluminum wire wrapped inside an insulating layer. Most cable TV companies use coaxial cables. A fiber optic cable consists of a central fiberglass core surrounded by several layers of protective material. This type of cable transmits light rather than electronic signals. A light emitting diode (LED) or laser is used to create the light pulses. The transmission speed of a fiber optic cable is much faster compared to the other cables. Most networks built today use a fiber optic cable because of its superior speed, but coaxial cable is also very common.

The most commonly used wireless connections use radio waves, microwaves and infrared waves. You obviously don't need cables for a wireless connection, but you will need other hardware for the transmission of wireless signals through the air.

Repeaters, Hubs, Bridges and Switches

A repeater is a device that receives electronic signals, cleans them and retransmits them at a higher power level. Signals transmitted over cable tend to degrade over long distances. Repeaters are needed so that the signal can travel longer distances.

A hub is a networking device used to connect multiple devices directly to the network using cables. Each connection is called a 'port.' The connections typically consist of a fiber optic Ethernet cable. When the hub receives data at one of its ports, it distributes the data to the other ports in the network. Typically, a hub sends all the data it receives to all the other ports.

Switches contain many ports to connect different network segments. They are similar to hubs, but offer greater performance. When a network contains a large number of devices, switches are needed instead of hubs to make sure the communications between devices do not slow down. Contrary to hubs, switches send the data it receives only to specific ports.

Bridges are networking devices that divide up the network into different segments to manage the amount of traffic. This prevents unnecessary traffic from entering other parts of the network and reduces congestion. As a network becomes more complex, bridges make sure your network speed doesn't drop dramatically.

Routers and Gateways

Routers are communication devices used to connect two different networks. A router sorts incoming data and distributes it to the correct destination. For example, if you have a network within a single office building, many different devices from within the network may access resources outside the network. The best example of this would be the Internet. A router ensures that requests from within the network for information over the Internet are distributed to the correct computer within the network.

The Internet itself uses numerous routers to direct all the traffic taking place. Such routers are typically very large and heavy-duty pieces of hardware, designed to handle huge amounts of data traffic. Routers can be used for wired connections, wireless connections or both. A router that provides a wireless connection is referred to as a 'wireless router.'

While routers are used to connect different networks, they only work if the network protocols are the same. A gateway interfaces networks that use different protocols. You can think of a gateway as a router that includes protocol translators. The terms 'router' and 'gateway' are often used interchangeably, but it is important to remember that only gateways make it possible to connect networks using different protocols.

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