Presentation on concept of Networking including the syllabus of class 8. Easy to understand and most important points are being covered here so that students can easily grasp the jest of the chapter

1. CHAPTER 4
Computer Networks

2. Chapter 4
• A computer network is a collection of computers and devices
connected by communications channels that facilitate
communication and sharing of resources among users.
• They may be classified according to a wide variety of
characteristics.
4.1 Local Area Network (LAN)
• It is a combination of programs and equipment that connect
a number of personal computers.
• It serves a local area.
• Supplies networking capability to a group of computers in
close proximity to each other such as in an office building, a
school or a home.

3. 4.1 Local Area Network (LAN)
• Feasible for the owning organization to install high quality, high-speed
communication links interconnecting nodes.
• Typical data transmission speeds are one to 100 megabits per second.
• Useful for sharing resources like files, printers, games or other applications.
• A LAN, in turn, often connects to other LANs and to the Internet or other WAN.
• Specialized operating system software may be used to configure a local area
network.
Examples: industrial plants, office buildings, college or university campuses or similar
locations.

4. 4.1 Local Area Network (LAN)
Ethernet LAN
• The smallest home LAN can have precisely two
computers; a large LAN can accommodate
many thousands of computers.
• Many LANs are divided into logical groups
called subnets.
• It sets up the predictable and inevitable
conflict between PCs, office automation
equipment and the larger midrange and
mainframe computers.

5. 4.1 Local Area Network (LAN)

6. 4.2 Wide Area Network (WAN)
• It is a collection of LANs.
• It spans a large geographic area, such as a state, a province
or a country.
• WANs often connect multiple smaller networks, such as local
area networks (LANs) or metro area networks (MANs).
• Many WANs are corporate or research networks that utilize
leased lines.
• Wide Area Network (WAN) is a computer network that
covers a broad area (i.e. any network, whose
communications links cross metropolitan, regional, or
national boundaries).

7. 4.2 Wide Area Network (WAN)

8. 4.1.1 LAN TOPOLOGIES
• Selecting the topology of the LAN is to
interconnect PCs, minicomputers, or both.
• This choice dictates the cable, cabling
methodology and the networking software
that can operate on the LAN.
• The three basic topologies are the ring, the
star and the bus or tree.

9. 4.1.1 LAN TOPOLOGIES

10. 4.1.2 Linear Bus Topology
Consists of a main run of cable with a
terminator at each end.
All nodes (file server, workstations, and
peripherals) are connected to the linear cable.

11. 4.1.2 Linear Bus Topology
A- Advantages of a Linear Bus Topology
• Easy to connect a computer or peripheral to a linear bus.
• Requires less cable length than a star topology.
B- Disadvantages of a Linear Bus Topology
• Entire network shuts down if there is a break in the main cable.
• Terminators are required at both ends of the backbone cable.
• Difficult to identify the problem if the entire network shuts down.
• Not meant to be used as a stand-alone solution in a large building.

12. 4.1.3 Star Topology
• Designed with each node (file server, workstations, and
peripherals) connected directly to a central network hub,
switch, or concentrator.
• Data on a star network passes through the hub, switch, or
concentrator before continuing to its destination.
• The hub, switch, or concentrator manages and controls all
functions of the network.
 It also acts as a repeater for the data flow.
 Common with twisted pair cable.
 Can also be used with coaxial cable or fiber optic cable.

13. 4.1.3 Star Topology

14. 4.1.3 Star Topology
a- Advantages of a Star Topology
• Easy to install and wire.
• No disruptions to the network when connecting or removing
devices.
• Easy to detect faults and to remove parts.
b-Disadvantages of a Star Topology
• Requires more cable length than a linear topology.
• If the hub, switch, or concentrator fails, nodes attached are
disabled.
• More expensive than linear bus topologies because of the cost of
the hubs, etc.

15. 4.1.4 Tree or Expanded Star
It combines characteristics of linear bus and
star topologies.
It consists of groups of star-configured
workstations connected to a linear bus
backbone cable.
They allow for the expansion of an existing
network.
They enable schools to configure a network to
meet their needs.

16. 4.1.4 Tree or Expanded Star

17. a- Advantages of a Tree Topology
• Point-to-point wiring for individual segments.
• Supported by several hardware and software venders.
b-Disadvantages of a Tree Topology
• Overall length of each segment is limited by the type of cabling used.
• If the backbone line breaks, the entire segment goes down.
Star and ring network topologies are sometimes combined into one network to provide a higher degree of fault tolerance.
Because a star network is susceptible to a failure in the hub and a ring network is sensitive to a break in the ring, combining
both forms offer an alternate route in case one topology fails.