Intro To Computer Networks

1
Intro To Computer Networks

• Basics

2
Objectives

• Explain digital vs. analog communications
• List types of cables
• List network devices
• Explain packet switching and circuit switching
• Describe role of protocols
• Describe various networks
• Recount basics of Internet and Internet access

3
Network-Basics

• A communications network is a collection of
  computers and other devices that communicate to
  share data, hardware and software
• In order to communicate, information must be
  transformed into the format the network uses

4
Network-Basics

• Computers use several coding schemes based on
  binary digits
• ASCII
• EBCDIC
• Unicode
• Binary numbers
• When data is transmitted, it usually takes the
  form of an electromagnetic signal
• On a communication network, your data may be
  converted into several different types of waves

5
Network-Basics

• Data can travel from one network device to
  another over a cable or through the air
• A communications channel is a physical path or a
  frequency for a signal frequency
• Networks use different types of cables

6
Transmission Media

• Wired Network
• twisted-pair cables- phone
• coaxial cable- TV
• Fiber-optic cable is a bundle of extremely thin
  tubes of glass
• Wireless Network
• Microwaves provide another option for
  transporting data
• Radio and microwave transmissions are bent around
  the surface of the earth to reach towers
• Communications satellites play an important part
  in long-distance communications
• A transponder on the satellite receives the
  signal, amplifies it, and retransmits the signal
  back to a ground station

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Network-Basics

• Bandwidth is the transmission capacity of a
  communications channel
• High-bandwidth communications systems, such as
  cable TV, are sometimes referred to as broadband
• Systems with less capacity, such as the telephone
  system, are referred to as narrowband
• The bandwidth of a digital channel is usually
  measured in bits per second (bps)

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Network Components

• Each device that is connected to a network is
  referred to as a node
• The term workstation usually refers to a personal
  computer connected to a local area network (LAN),
  it is also called a client
• A modem is a device that converts signals from a
  computer into a signal that can travel over a
  wide area network

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Network Components

• A network interface card (NIC) is the key
  hardware component for connecting a computer to a
  local area network.
• small circuit board that sends data to and from
  workstation to network
• A server refers to any computer on a LAN or the
  Internet that contains the software to manage and
  process files for other network nodes

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Network Components

• A host computer usually refers to any computer
  that provides services to network users
• A hub is a device that connects several nodes of
  a LAN
• A router is a device that is connected to at
  least two networks and makes decisions about the
  best route for data
• A gateway is a device that performs functions
  similar to a router
• A repeater amplifies and regenerates signals so
  they can retain the strength to reach their
  destinations

11
Protocols

• Communications protocol refers to set of rules
  for transmitting data from one node to another
• Protocols allow two devices to negotiate and
  agree on how data will be transmitted

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Network-Basics

• Simplex signal travels in only one direction
• Half duplex signal travels in both directions,
  but only one direction at a time
• Full duplex signal travels in both directions
  at the same time

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Network Classifications

• Internetwork a network composed of many smaller
  networks
• Intranet uses TCP/IP protocols but owned by a
  private business and does not typically allow
  remote access
• Extranet similar to intranet except that it
  allows remote password-protected access
• WAN (wide area network) covers a large
  geographical area and may consist of smaller
  networks
• LAN (local area network) typically covers a
  very limited geographical area