2.1 Line configuration

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2? ??? ?? ?? ??

• 2.1 ?? ??(Line configuration)
• 2.2 ????(Topology)
• 2.3 ?? ??(Transmission mode)
• 2.4 ???? ??(Categories of Networks)
• 2.5 ??????(Internetworks)
• 2.6 ??

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?? ??

• Fives general concepts provide the basis for the
  relationship between the communicating devices.
• Line configuration
• Topology
• Transmission mode
• Categories of Networks
• Internetworks

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2.1 ?? ??

• refer to the way two or more communication
  devices attach to a link.
• defines the attachment of communication devices
  to a link

Line configuration
Multipiont
Point-to-point
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?? ??(contd)

• ?-?-?(Point-to-point)
• provides a dedicated link between two devices.
• ?????(Multipoint)
• is one in which more than two specific devices
  share a single link

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?? ??(contd)

• ?-?-? ?? ??

Link
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?? ??(contd)

• ?-?-? ?? ??

Link
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?? ??(contd)

• ?-?-? ?? ??

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?? ??(contd)

• ?? ??? ?? ??

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2.2 ????(Topology)

• refer to the way a network is laid out, either
  physically or logically
• defines the physical or logical arrangement of
  link in a network
• A consideration when choosing a topology is the
  relative status of the devices to be linked.
• peer-to-peer the devices share the link
  equally(ring, mesh)
• primary-secondary one device controls traffic
  and the others must transmit through it

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???? ??(Categories of topology)
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Mesh

• every device has a dedicated point-to-point link
  to every other device.
• A fully connected mesh network therefore has
  n(n-1)/2 physical channels to link n devices.

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Mesh(contd)

• Advantages
• the use of dedicated links guarantees that each
  connection can carry its data load.
• a mesh topology is robust.
• Privacy and security.
• Point-to-point links make fault identification
  and fault isolation easy.

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Mesh(contd)

• Mesh topology

of full-duplex links of the fully-connected one
hop network with N nodes N(N-1)/2. eg. N10, of
links 45 N 100, of links 5000.
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Mesh(contd)

• Disadvantage
• are related to the amount of cabling and the
  number of I/O ports
• because every device must be connected to every
  other device, installation and reconfiguration
  are difficult
• the sheer bulk of the wiring can be greater than
  the available space(in walls, ceiling, or floors)
  can accommodate
• the hardware required to connect each link(I/O
  port and cable) can be prohibitively expensive

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Star

• each device has a dedicate point-to-point link
  only to a central controller, usually called a
  hub.

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Star(Contd)

• Star topology

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Star(contd)

• Advantage
• each device needs only one link and one I/O port
  to connect it to any number of others(easy to
  install and reconfigure)
• robustness
• if one link fails, only that link is affected

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Tree

• is a variation of a star
• simple shared hub(wiring concentrator)
• active hub(central hub)
• contains a repeater, which is a hardware device
  that generates the received bit patterns before
  sending them out
• passive hub
• provides a simple physical connection between
  the attached devices
• switching hub
• provides a switching function
• intelligent Hub
• network management function

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Tree(contd)

• Tree topology

Hub
Hub
Hub
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Tree(contd)

• Advantage Disadvantage
• are generally the same as those of a star

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Bus

• is multipoint. One long cable acts as a backbone
  to link all the device in the network
• Nodes are connected to the bus cable by drop
  lines and taps
• drop line
• is a connection running between the device and
  the main cable
• tap
• is a connector either splices into the main
  cable or punctures the sheathing of a cable to
  create a contact with the metallic core

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Bus(contd)

• Bus topology

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Bus(contd)

• Advantage
• include ease of installation
• Disadvantage
• include difficult reconfiguration and fault
  isolation

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Ring

• each device has a dedicated point-to-point line
  configuration only with the two devices on either
  side of it
• Advantage
• is relatively easy to install and reconfigure
• fault isolation is simplified
• Disadvantage
• unidirectional traffic
• break in the ring can disable the entire
  network(dual ring)

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Ring(contd)

• Ring topology

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Hybrid topology
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2.3 ????(Transmission mode)

• is used to define the direction of signal flow
  between two link devices
• ???(Simplex)
• is unidirectional, as on a one-way
  street(keyboard, monitor)
• ???(Half-Duplex)
• each station can both transmit and receive, but
  not at the same time
• ???(Full-Duplex)
• both stations can transmit and receive
  simultaneously

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????(contd)
Transmission modes
Half-duplex
Simplex
Full-duplex
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????(contd)

• ???(Simplex)

Direction of data
Monitor
Mainframe
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????(contd)

• ???(Half-Duplex)

Direction of data at time 1
Direction of data at time 2
Workstation
Workstation
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????(Full-Duplex)

• ???(Full-Duplex)

Direction of data at all the time
Workstation
Workstation
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2.4 ???? ??(categories of Networks)

• three primary categories
• LAN
• MAN
• WAN
• size, ownership, distance it cover, physical
  architecture

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???? ??(contd)
Network
Wide area network (WAN)
Metropolitan area network (MAN)
Local area networks (LAN)
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???? ??(contd)

• LAN(Local Area Networks)
• is usually privately owned and links the
  devices in a single office, building or campus

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???? ??(contd)

• Single building LAN

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???? ??(contd)

• Multiple building LAN

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???? ??(contd)

• MAN(Metropolitan Area Networks)
• is designed to extend over an entire city

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???? ??(contd)

• MAN

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???? ??(contd)

• WAN(Wide Area networks)
• provides long-distance transmission of data,
  voice, image, and video information over large
  geographical areas that may comprise a country, a
  continent, or even the whole world

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???? ??(contd)

• WAN

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2.5 ??????(Internetworks)

• is an interconnection of networks by the use of
  internetworking device(router and gateway)
• cf
• internet an interconnection of networks
• Internet a specific worldwide network

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Internetworks(internet)
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2.6 ??

• ??
• Exercise 3,5,7