| Network media is what is used to connect Point | | | | CAT 1 - your basic cheap telephone wire. It uses |
| A to Point B. Most people think of media as | | | | 2 pairs of wires. |
| cables, but air is also media for wireless devices. | | | | CAT 2 - also for telephones or alarm systems. It |
| I will explain several different types of media - | | | | uses 2 pairs of wires. |
| Coaxial cable, Unshielded Twisted Pair cable, fiber | | | | CAT 3 - higher quality, and you can send data on |
| optic cable, and wireless media (air). | | | | it - up to 16 Megabits per second (Mbps). It uses |
| Coaxial Cable | | | | 4 pairs of wires. Out of those, only 2 pairs are |
| Coaxial cable, also known as "coax", utilizes one | | | | used (4 wires). |
| wire. There is a copper wire in the middle of the | | | | CAT 4 - 20 Mbps, 4 pairs. |
| cable that is used for data transmission. Around it, | | | | CAT 5 - 100 Mbps, 4 pairs, higher quality (more |
| there is an insulator that prevents the copper | | | | twists per inch). |
| cable from touching the braided shield layer. If the | | | | CAT 6 - 1Gbps (Gigabit per second), 4 pairs, very |
| copper core touched the shield layer, the signal | | | | high quality with several more twists per inch. Also |
| would get scrambled or there could be an | | | | the pairs are twisted around each other. |
| electrical short, so the insulator prevents that. The | | | | Fiber Optic Cable |
| braided metal shield is to keep outside | | | | Fiber optic cables use light, therefore almost |
| interference to a minimum. The interference, or | | | | eliminating interference. Electrical signals and |
| noise, that occurs from other equipment like | | | | magnetism will not interefere with the light signals |
| lights, motors, or any electrical device, can | | | | inside of a fiber optic cable. The light signals will be |
| interfere with the signal in the copper core. The | | | | produced with either a laser or a light emitting |
| shield conducts the noise as it comes near the | | | | diode (LED). A laser is more powerful and |
| cable, and it is grounded. The shield is connected | | | | expensive, so it is used for long distance cables, |
| to a ground when you plug the cable in, so the | | | | while LEDs are used for shorter distances. |
| electrical noise gets terminated. | | | | There are two different types of fiber used - |
| Electricity flows on the outside of the copper | | | | single mode and multi mode. The single mode |
| wire, so the thickness of the wire makes a | | | | fiber has a smaller diameter than multi mode fiber. |
| difference. You can't send as much electricity | | | | It is so small that it is actually more expensive to |
| through a thinner wire or else it will get hot and | | | | make than multi mode fiber. Around the fiber is a |
| catch on fire or melt. If you pass the same | | | | cladding. The cladding reflects the light along the |
| amount of electricity through a thicker wire, it | | | | fiber. With a thinner fiber, there is less room for |
| won't get hot. This is where standards come in. | | | | the light to bounce around, and therefore it can |
| You want to get the right cable so the electricity | | | | go a longer distance before the light dissipates and |
| can flow correctly. The more data you transmit, | | | | the signal gets too weak. Because single mode |
| the more electricity is sent through the cable. | | | | fiber is more expensive and can go longer |
| These cables have an extremely low voltage, so | | | | distances, it is commonly used in WANs (Wide |
| they won't catch on fire if you use the wrong | | | | Area Networks), while multi mode is commongly |
| one, but the data might not get tranmitted | | | | used in LANs (Local Area Networks). |
| correctly if you use the wrong cable. There are | | | | Wireless |
| distance limitations on these cables. For example, | | | | Just as it sounds, wireless networks don't use |
| you could have an RG-58 cable that is up to 185 | | | | wires, they use radio frequency. The 3 primary |
| meters long, but if it were any longer, the signal | | | | wireless standards are 802.11a, 802.11b, and |
| would start to get weaker and it would become | | | | 802.11g. 802.11 is the IEEE standard for wireless |
| unreadable by the computer or device you want | | | | communication. |
| to communicate with. | | | | 802.11a uses the 5GHz frequency to |
| Thin Ethernet, or RG-58, has a distance limitation | | | | communicate. It can communicate at 54Mbps, |
| of 185 meters. | | | | which is fast for wireless, but it has a short range |
| Thick Ethernet, or RG-8 or RG-11, has a distance | | | | of 150 feet. |
| limitation of 500 meters. | | | | 802.11b uses the 2.4GHz frequency to |
| ARCNet, or RG-62, has a variable distance | | | | communicate. It can communicate at just 11Mbps, |
| limitation. | | | | but it has a range of 300 feet. Because it uses |
| UTP Cable | | | | the 2.4GHz frequency, you might run into some |
| UTP stands for Unshielded Twisted Pair. These | | | | problems when using a cordless phone or |
| cables are just copper wire pairs with no shield. | | | | microwave, because many of those products also |
| Each pair of wires is twisted to prevent | | | | use the 2.4GHz frequency. |
| interference, or crosstalk. Since there are several | | | | 802.11g also uses the 2.4GHz frequency to |
| wires in the cable, the electrical signal on one wire | | | | communicate. It can communicate at 54Mbps and |
| could interfere with another wire's signal. So each | | | | has a range of 300 feet. Even though it uses the |
| pair is twisted, which forms sort of a force-field | | | | same frequency as 802.11b, it is faster because it |
| around the pair to lessen interference. The more | | | | sends and recieves data differently. |
| twists per inch on the wire, the more protection it | | | | 802.11g is backwards-compatible with 802.11b. This |
| has against interference, and therefore it is better | | | | means that if you have an 802.11b network, and |
| quality. | | | | a laptop with an 802.11g wireless card, it will be |
| The UTP cables are labeled with a category, or | | | | able to connect to the network. The 802.11g card |
| CAT. UTP cables have a distance limitation of 100 | | | | will just slow down to 11Mbps (the limit on 802.11b |
| meters when sending binary data (not analog | | | | networks). |
| data, such as telephone communication). | | | | |