Network Connection Devices

Its easy to forget about all the small pieces of hardware that sit and hum along 24-7 just so that we can check our email or catch the latest stats for our fantasy team. Just what are those little boxes and why do they have so many little blinking lights?

Network connections are made possible by two main types of hardware: network media and network connectivity devices. This article is going to cover the later in enough detail to have you picking up the network-speak in no time. Network connection devices include:

• Network interface cards (NIC)
• Hubs
• Switches
• Bridges
• Routers
• Gateways
• Modems

A NIC (network interface card) is a piece of hardware that allows you to plug in–or, interface with– a network cable. NIC’s are usually installed as an expansion card or is already built into your motherboard.

Hubs are devices that connect all of the segments of a network together. That is, every device on the network (computers, printers) has a cable that is also connected to the hub. Hubs work in such a way that every signal that is received on one port is rebroadcast to every other device. So, if one device sends a signal, all the other devices receive the signal, but only one particular device listens for it.

A switch is like a hub in that every device on the network is connected to it. However, a switch does not rebroadcast signals to all other devices. A switch makes a direct link between the device that is transmitting and the device that is receiving. All other devices are totally unaware of the communication taking place. For this reason, switches realize greater performance because bandwidth is not being wasted on needless rebroadcasting.

A bridge is used to to keep network traffic separated between network segments. Traffic is not allowed to pass through the bridge unless its destination is on the other side. Bridges are used to join to network segments or to divide a busy network into two segments.

Routers are devices that can connect several network segments (even segments that are not alike in type). The router has the ability to make decisions about the best way to send network traffic to its destination.

A Gateway is any device that connects network environments that are not alike. For example, a gateway is used to connect LAN (local area network) environments to mainframe environments.

Modems (modulator/demodulator) are devices that change digital data into analog for transmission over analog network medium and then back to digital at the receiving end. There are several types of modems; some losing popularity and others gaining more and more use. These are:

• Telephone (POTS – Plain Old Telephone Service)
• DSL (Digital Subscriber Line)
• Cable

I hope this has shed some light on the various network connection devices. Of course, there’s an enormous amount on information on this subject out on the web. If you’re really serious about getting into networking, grab a study guide for getting certified in the subject (Network +). These books have zero fluff and do a great job presenting the material. They are invaluable and can be very helpful… even if you’re not looking to get certified.