Chris Inman

AIL 603

General Networking Information Assignment

1. Describe the importance of the following individuals and entities in relation to networks:

  • Samuel F.B. Morse
  • Samuel Morse is credited with inventing the telegraph, which sent signals over wire. It is believed that Morse had a working model as early as 1835, but he did not obtain a patent until 1837. The telegraph was demonstrated in 1838, marking the beginning of what would be known as “Morse Code”. By 1846 private companies across the United States began to install their own telegraph networks based upon Morse’s patent. For the first time, information could be sent instantaneously from one city to the next without need of a human courier.
  • Alexander Graham Bell
  • Bell is credited with inventing the telephone, though in February 1876 Bell and Elisha Gray actually took their competing patents of the telephone to the patent office on the same day. Bell won the legal fight, thus earning sole credit for the invention. Eventually, the telephone overtook the telegraph. Over one hundred years later, the telephone is still the primary tool for communication between people.
  • Emile Baudot
  • Baudot, a French inventor, patented a new telegraph code in 1874 which eventually supplanted the Morse Code by the mid-20th Century. In 1894 Baudot invented a distribution system for multiple transmissions of several messages over the same telegraph circuit or channel.
  • Donald Murray
  • A British inventor, in 1903 Murray, building upon the work of Baudot, invented a time-division multiplex system for the British Post Office. In the system, a typewriter keyboard punched tape while the receiver printed text. In 1912, Murray sold his patent to Western Union & Western Electric, and this development led to the printing telegraph systems used in the 1920s. In the 1920s AT&T introduced its own system, called Teletype, which was used in business communication. These systems used a modified Baudot code, up until the advent of the computer in the 1960s.
  • Elisha Gray
  • Gray lost a patent battle over the telephone to Alexander Graham Bell. However, Gray invented a device called the telautograph. The telautograph was the first device to transmit drawings to a stationary sheet of paper. Today, the fax machine is the modern version of the device
  • Almon Brown Strowger
  • Strowger is credited with inventing the first automatic telephone exchange, patented in 1891. The system removed the need for a human being switch operator, since the switch was automatic. Now, a person could telephone a person directly, rather than telephoning a switch board operator and requesting a connection to a number.
  • Western Union
  • Founded in the 1850s, Western Union functioned as a communication network based around the telegraph. In 1861, the company established the first transcontinental telegraph across North America. As the telephone supplanted the telegraph, Western Union shifted its business focus to customer money transfers via wire. In the 1940s, the company introduced the first inter-city commercial microwave communication system. In 1974, Western Union launched the first commercial U.S. satellite.
  • The Carterfone
  • Created by Thomas Carter, the Carterfone could connect a two-way mobile radio system to a public switched telephone network. In the late 1960s the Carterfone was involved in a court case whereby it was ruled that the Carterfone (and other devices) could connect to the AT&T network as long as it did not damage the system. The decision allowed non-AT&T products and devices to be connected to the AT&T network, thus ending the AT&T monopoly. Devices such as fax machines, cordless phones, and modems could now connect to the system.

2.Discuss the similarities and differences between DSL and cable modems, including speed, security, advantages and disadvantages.

  • DSL v. Cable Modems
  • Speed: In theory, cable Internet should be faster than DSL due to higher levels of bandwidth, but this advantage could be eliminated for technical reasons. In terms of raw speed, cable modems support approximately 30 megabits per second (Mbps) while DSL supports only 10 Mbps.
  • Security: Relatively speaking, both DSL and cable offer the same level of security, since both allowed the capability to be online at all times. Many, however, believe that DSL is more secure than cable, since cable users in a region are all connected to the same network, or LAN. Concerns aside, if users take the proper security precautions (installing network firewall software, anti-virus software, etc.) then security should be roughly equal.
  • Availability: Cable has a slight edge over DSL in this category. Generally speaking, more homes have cable subscription than phone subscription. Also, if your cable company advertises cable Internet access then you can probably purchase the service. With DSL, even if you are within distance of the phone company you still may have issues connecting for technical reasons.
  • Performance: Both DSL and cable have advantages in this category. Theoretically, cable should provide better performance due to better bandwidth and due to the fact that distance to a central office has no impact on performance. With DSL, performance is largely tied to your location in relation to a central office. The further you are from a central office, the slower the performance.
  • Making a choice: Choosing between the two really comes to you needs as a consumer. Generally, cable is cheaper than DSL, but the gap is narrowing. Both have the same level of security, provided security measures are taken. If you live far away from a central office, then cable would be a better system. Conversely, if you live somewhat close to a central office and connecting is not an issue, then DSL may be a better system. I personally use cable and have never had any problems.

3. TV remote controls were some of the first devices to use infrared signals generated by light-emitting diodes. However, TV remote controls date back to 1950 when Zenith introduced the first remote control, the Lazy Bones. Using the Internet and printed sources, trace the development of the TV remote control as one of the pioneers of infrared technology. Explain how other technologies, such as radio frequency and ultrasonics, were proposed, but rejected. What are the capabilities and limitations of today’s infrared remotes?

ANSWER: The first television remote control, the “Lazy Bones”, was created by Zenith in the 1950s. The Lazy Bones actually was not a wireless remote, but was connected to the computer by a cable. The remote could turn the television on and off, and could change the channel, but costumers did not like the remote because people often tripped over the cable. In 1955 Zenith engineer Eugene Polley invented the “Flash-matic”, the first wireless remote. The “Flash-matic” utilized four photocells in the four corners of the television. A flashlight was directed into specific corners to either turn the television on and off, change the volume, or tune the television. The “Flash-matic” proved unpopular because people often forgot which corner handled specific commands, and the television was so light sensitive that the channel who change or the television would simply turn off due to sunlight. The next year, Dr, Robert Adler Zenith developed the “Zenith Space Command” remote which utilized ultrasonics, and this remote would remain in use for the next twenty-five years. By the early 1980s, scientists realized a new type of remote was needed because the high frequency ultrasound used by the remote was sometimes heard by people and dogs, and noises sometimes changed television channel or turn it on or off. Therefore, a shift, once again led by Zenith, was toward infrared remote technology occurred. Today, most television remotes use infrared technology. The infrared remote uses a low frequency light beam, a beam so low the human eye cannot detect it. There are a few limitations of the infrared remote: 1) clear line of sight from the remote to the television sensor; 2) Can be block by common materials, people, or animals; 3) the longer the distance, the lower the effectiveness; 4) Direct sunlight, rain, fog, dust, or pollen can impact transmission. Still, infrared technology is generally reliable and low cost, is usually more secure, and is not negatively impacted by noise.

4. Describe IP addresses, including what they are, how they work, how to figure out your own IP address, and fixing IP addressing problems.

  • IP address: an identifier for a computer or device on a TCP/IP network. Networks using the TCP/IP route messages based upon the IP address of the destination. The format of an IP address is a 32-bit numeric address written as four numbers separated by periods. Each number can be 0 to 255. Isolated networks can assign IP addresses at random as long as each address is unique. Connecting to a private network to the Internet requires using a registered IP address.
  • An IP Address consists of two parts, one specifying the network, and the other identifying the host. This information is important because it helps you identify the correct Network class. IP Addresses generally fall into three categories: Class A, Class B, and Class C.
  • Class A: The binary number begins with a 0, and the decimal number can be any number between the numbers 1 to 126. The first 8 bits (or 3 numbers) identify the network, and the remaining 24 bits (or 9 numbers) identify the host. For example: IP Address 76.27.144.128- (76) identifies the network and (27.144.128) identifies the host.
  • Class B: The binary number begins with 10, and the decimal number can be between numbers 128 and 191. The first 16 bits (6 decimal numbers) identify the network, and the second 16 bits (6 decimal numbers) identify the host. For example: IP Address 176.129.144.128- (176.129) identifies the network and (144.128) identifies the host.
  • Class C: The binary number begins with 110, and the decimal number can be between numbers 192 and 223. The first 24 bits (9 decimal numbers) identify the network, and the second 8 bits (3 decimal numbers) identify the host. For example: IP Address 196.193.144.128- (196.193) identifies the network and (144.128) identifies the host.
  • Two additional categories: Class D and Class E
  • Class D: The binary addresses start with 1110, and the decimal number can be anywhere from 224 to 239. Class D networks are used to support multicasting.
  • Class E: The binary addresses start with 1111, and the decimal number can be anywhere from 240 to 255. Class E networks are used for experimentation and have not yet been documented or utilized in a standard way.
  • Figuring out your IP Address: There are several Web sites which will tell you the IP Address of your computer. One such site is My IP Address is 76.27.144.128. For computers running Windows NT, 2000, or XP: 1) click on the Start Menu; 2) Click on “Run”; 3) In the “Run” box, type ‘cmd’; 4) A command box should appear. Type ipconfig /all in box, and your IP address should appear. To find the IP address and Media Access Control (MAC) address of a computer running Windows 95, Windows 98, or Windows ME follow the first two steps from above. In the “Run” box, type ‘winipcfg’. The "IP Address" field displays the IP address for the default network adapter. The "Adapter Address" field displays the MAC address for this adapter.
  • Converting IP Address to Binary: The binary number “1” has the values of (128, 64, 32, 16, 8, 4, 2, 1). If a slot is open, it has binary number of “1”. If a slot is closed it has a binary number of “0”. The binary scale must be read from right to left. For example, 76.27.144.128 converted to binary is 01001100.00011011.10010000.10000000. The “76” equals “01001100” because the 3rd, 4th, and 7th slots are all open, and the values for those slots are equal to 4 + 8 + 64, which equals “76”.
  • Fixing IP Address Problems: Sometimes problems occur with IP addresses. These could include 1) a computer not having an IP address, 2) two computers having the same address, 3) or a computer has a bad address that will not allow it to communicate, or talk to, the network. Three actions can generally be taken to solve these problems:
  • Release or Renew an IP Address (works with Windows XP, 2000, and NT): 1) Click the Start menu button; 2) Click “Run”; 3) In the “Run” box, type ‘cmd’ (with quotes), and the command prompt box will appear; 4) Type ipconfig to view the IP status of your computer; 5) If the computer is holding a current IP address, type 'ipconfig /release' to let go of the address; or 6) Type 'ipconfig /renew' to obtain a new IP address (whether or not the computer is holding a current address)
  • Change from dynamic IP address to a static IP address: Changing to a static IP address could provide more security for a home computer. The new address should be chosen from among three ranges: 1) 10.0.0.0 through 10.255.255.255; 2) 172.16.0.0 through 172.31.255.255; 3) 192.168.0.0 through 192.168.255.255.
  • Apply a subnet mask: A subnet mask can also improve security. The subnet mask to an IP address splits the address into two parts: 1) an "extended network address" and 2) a host address.

5. Describe the differences between analog and digital signals.

  • Analog: An analog signal is a sine wave system which carries information, and is a continuous signal which changes over time. The analog wave can have any one of a set of infinite values within the range.
  • Digital: A digital signal is quite different from an analog signal. Digital signals are square waves and are not continuous. The wave or signal is composed of pulses (digits) which maintain constant values, with abrupt changes from one digit to the next. While an analog wave can have several amplitude values, a digital wave only has two values, called nodes. They are usually expressed as either/or combinations such as 1 or 0, High or Low, or True or False. Telecommunications use mostly digital signal technology today, since digital can provide superior sound quality and cost less than analog devices and equipment.