MODULE 3 - Network Media Types

Explain each Network Media Types. Include images and proper examples.

- Coaxial cable
- Twisted-pair cable (UTP & STP) (Straight-through, crossover, rollover cable)
- Fiber-optic cable
- Wireless Technologies (802.11, 802.11b, 802.11g, 802.11g, 802.11n)

Coaxial cable

Coaxial  cable

A Coaxial cable is a cable used in the transmission of video, communications, and audio. This cable has high bandwidths and greater transmission capacity. Most users relate to a coaxial or coax cable as a cable used to connect their TVs to a cable TV service. However, these cables are also used in networks and what allow a broadband cable Internet connection using a cable modem. The picture is an example of a coaxial cable.

Twisted Pair

Twister Pair cable

A twisted-pair cable is a cable made by intertwining two separate insulated wires. There are two twisted pair types: shielded and unshielded. A Shielded Twisted Pair (STP) has a fine wire mesh surrounding the wires to protect the transmission; an Unshielded Twisted Pair (UTP) do not. Shielded cable is used in older telephone networks, as well as network and data communications to reduce outside interference. The illustration gives an example of how the inside of these wires  look like.

Straight-through cable:

A straight-through cable is a type of twisted pair cable that is used in local area networks to connect a computer to a network hub such as a router. This type of cable is also sometimes called a patch cable and is an alternative to wireless connections where one or more computers access a router through a wireless signal.

Crossover cable:

Crossover cable

A crossover cable is a type of cable installation that is used for the interconnection of two similar devices. It is enabled by reversing the transmission and receiving pins at both ends, so that output from one computer becomes input to the other, and vice versa.

Rollover cable:

Rollover cable

A rollover cable is a network cable that connects a computer terminal to a network router’s console port. It is also referred to as a Cisco console cable and is normally flat and light blue so as to distinguish it from other network cable types. The pin-outs on one end of the cable are reversed from the opposite end, which is how the cable derived its name. Rollover cables are also known as Yost cables or Yost Serial Device Wiring Standard connectors.

Rollover cables primarily connect a device to a switch or router’s console port. This permits programmer to connect to the network device and manipulate the programming as required. Although many network programming tasks can now be centrally completed, there remains the need for technicians to use rollover cables for network hardware upgrades, maintenance, and troubleshooting.

Fiber-optic cable

Fiber-optic cable

A technology that uses glass (or plastic) threads (fibers) to transmit data. A fiber optic cable consists of a bundle of glass threads, each of which is capable of transmitting messages modulated onto light waves.
Fiber optics has several advantages over traditional metal communications lines:

Fiber optic cables have a much greater bandwidth than metal cables. This means that they can carry more data.

Fiber optic cables are less susceptible than metal cables to interference.

Fiber optic cables are much thinner and lighter than metal wires.

Data can be transmitted digitally (the natural form for computer data) rather than analogically.

Wireless Technologies

Wireless

Wireless communication is among technology’s biggest contributions to mankind. Wireless communication involves the transmission of information over a distance without help of wires, cables or any other forms of electrical conductors. The transmitted distance can be anywhere between a few meters (for example, a television’s remote control) and thousands of kilometres (for example, radio communication).

Some of the devices used for wireless communication are cordless telephones, mobiles, GPS units, wireless computer parts, and satellite television.

Wireless communication has the following advantages:

i.      Communication has enhanced to convey the information quickly to the consumers.

ii.        Working professionals can work and access Internet anywhere and anytime without carrying cables or wires wherever they go. This also helps to complete the work anywhere on time and improves the productivity.

iii.    Wireless networks are cheaper to install and maintain.

802.11 Wireless

       The wireless local area network (WLAN) protocol, IEEE 802.11, and associated technologies, such as the 802.1X protocol and Wi-Fi Protected Access (WPA), allow secure high-speed wireless network access and mobile access to a network infrastructure. Until the recent development and wide adoption of IEEE 802.11b, also known as Wi-Fi, in order to obtain high-speed network access to your local area network (LAN) your network client needed to be physically connected to the LAN with some type of wiring.

Benefits

       Some of the specific benefits of implementing a WLAN are included in the following:

    In situations where it is costly, inconvenient, or impossible to lay cables, wireless connections can extend or replace a wired infrastructure. This benefit includes the following:

•        To connect the networks in two buildings separated by a physical, legal, or financial obstacle, you can either use a link provided by a telecommunications vendor (for a fixed installation cost and ongoing recurring costs) or you can create a point-to-point wireless link using wireless LAN technology (for a fixed installation cost, but no recurring costs). Eliminating recurring telecommunications charges can provide significant cost savings.
  
  
•        Wireless LAN technologies can be used to create a temporary network, which is in place for only a specific amount of time. For example, the network needed at a convention or trade show can be a wireless network, rather than deploying the physical cabling required for a traditional Ethernet network.
  
  
•        Some types of buildings, such as historical buildings, might be governed by building codes that prohibit the use of wiring, making wireless networking an important alternative.

802.11b Wireless

       The 802.11b standard for wireless local area networks (WLAN) - often called WI-FI- is part of the 802.11 series of WLAN standards from the Institute of Electrical and Electronics Engineers (IEEE). 802.11b is backward compatible with 802.11.

       Like other 802.11 standards, 802.11b uses the Ethernet protocol and CSMA/CA (carrier sense multiple access with collision avoidance) for path sharing. The modulation used in 802.11 has historically been phase-shift keying (PSK). The modulation method selected for 802.11b is known as complementary code keying (CCK), which allows higher data speeds and is less susceptible to multipath-propagation interference.

802.11g Wireless

      The 802.11g specification is a standard for wireless local area networks (WLANs) that offers transmission over relatively short distances at up to 54 megabits per second (Mbps), compared with the 11 Mbps theoretical maximum with the earlier 802.11b standard. 

      Networks employing 802.11g operate at radio frequencies between 2.400 GHz and 2.4835 GHz, the same band as 802.11b. But the 802.11g specification employs orthogonal frequency division multiplexing (OFDM), the modulation scheme used in 802.11a, to obtain higher data speed. Computers or terminals set up for 802.11g can fall back to speeds of 11 Mbps. This feature makes 802.11b and 802.11g devices compatible within a single network. Modification of an 802.11b access point to 802.11g compliance usually involves only a firmware upgrade.

802.11n Wireless

       802.11n is a specification for wireless LAN (WLAN) communications. 802.11n, an addition to the 802.11family of standards, will increase wireless local area network(WLAN) speed, improve reliability and extend the range of wireless transmissions.

       802.11n uses multiple input / multiple output (MIMO) technology and a wider radio frequency channel. It also provides a mechanism called frame aggregation to decrease time between transmissions. 

Differences between 802.11a, 802.11b, 802.11g and 802.11n

FIX:

802.11a:        Operates in the 5.15GHz to 5.35GHz radio spectrum.        Speed: Up to 54Mbps (actual throughput is closer to 22Mbps)        Range: 50 feet        Less prone to interference.        More expensive.        Because 802.11b and 802.11a use different radio technologies and portions of the spectrum, they are incompatible with one another.      802.11b:        Operates in the 2.4GHz radio spectrum.        Speed: Up to 11Mbps        Range: 100 feet        Prone to interference (it shares airspace with cell phones, Bluetooth, security radios, and other devices).        Least expensive wireless LAN specification.        The Wireless Ethernet Compatibility Alliance (WECA) has done its part by certifying hundreds of products to make sure they work together.      802.11g:        Operates in the 2.4GHz radio spectrum.        Speed: Up to 54Mbps        Range: 100 feet        Prone to interference (it shares airspace with cell phones, Bluetooth, security radios, and other devices).      802.11n (Draft):      Operates in the 2.4 or 5GHz radio spectrum      Speed: Up to 700Mbs      Range: 50 feet        Because 802.11b and 802.11g use the same radio technologies and portions of the spectrum, they are compatible with one another. But because the 802.11n standard has yet to be ratified by WECA, it may not be completely compatible with 802.11b and 802.11g.