Computer Networks
Software Engr. Imdad Manik
03007060570

1
Objectives for Network Design
• To minimize DOWNTIME
• Allows users to work with other users
regardless of computers used
...
What is a network ?
• A collection of computers and devices
connected by communication channels
that allows more users to ...
What is a Network ?
• All Network must have…..

- Something to share (data)
- A physical pathway (Transmission
Medium)
- P...
Typical Network

IBM Regatta

Multiplexor
Serial

Parallel

Windows 98
Country-wide Branches

18 units
Printers
At 15 bran...
Network Criteria

Performance

Reliability

Security
6
Performance

 # of users
 Medium
 Hardware
 Software

7
Why ?

To Share Peripherals







Printers
Scanners
Hard Disk
CD Rom
Plotters
Tape Backup

Reduce
Cost

8
Why ?

• Enabling Common
Administration & Security
• Network Applications

• Email
• Database Service
• Groupware

9
Types of networks

1. Local Area Network (LAN)
2. Metropolitan Area Network
(MAN)
3. Wide Area Network (WAN)

10
Local Area Network - LAN
 A network that connects computers in a
limited area such as a school, company,
or building.
 C...
Local Area Network - LAN
The two popular types of LANs are :

1. Peer-to-Peer.
2. Client / Server.

12
Peer-to-peer LAN

13
Client / Server

14
METROPOLITAN AREA
NETWORK (MAN)
• MANs connect locations that are
geographically located from 5 to 50
kilometres.
• They i...
Wide Area Network - WAN
• Covers a large area using a communication
channel.
• Connects two or more LANs.
• Internet is th...
NETWORK TOPOLOGY
• The configurations used to describe
networks are sometimes called Network
architecture or network topol...
Ring network
• Data travels around the ring in one direction.
• The message knows the destination because
each workstation...
Ring network topology

19
Bus Network
• Connects all networked devices to a single
cable (called the Bus) running the length
of the network.
• Advan...
Bus Network Topology

21
Star Network
•
•
•
-

All devices on the network are connected to a central device that
controls the entire network.
The c...
Star Network Topology

23
Mesh Network
• Each node has a direct point to point
connection to every other node in the
network.
• Provides best perfor...
Mesh Network Topology

25
Hybrid Network
• Combination of more
than one of the
network
configurations.
Example: a bus
network may have a
ring networ...
LAN Architectures
• Together with the appropriate
transmission media, the LAN topologies
provide the basic physical elemen...
Thank You
• Kindly give the feedback with your
supporting comments to rise for better
presentation ..

28
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Computer Networks

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Computer Networks

  1. 1. Computer Networks Software Engr. Imdad Manik 03007060570 1
  2. 2. Objectives for Network Design • To minimize DOWNTIME • Allows users to work with other users regardless of computers used • The network should expand as they find other users for it. • To keep outsiders from unauthorized access • The ability to manage their networked 2 devices from one place
  3. 3. What is a network ? • A collection of computers and devices connected by communication channels that allows more users to share resources like data, information, hardware, and software. • A group of interconnected systems sharing services and interacting by means of a shared communications link. 3
  4. 4. What is a Network ? • All Network must have….. - Something to share (data) - A physical pathway (Transmission Medium) - Protocols 4
  5. 5. Typical Network IBM Regatta Multiplexor Serial Parallel Windows 98 Country-wide Branches 18 units Printers At 15 branches Multiplexor Windows 2000 with Designer Software Protocol : TCP/IP Serial NT Server Axis 560 Windows 2000 with Lapres Run-time 7 units Printers 5
  6. 6. Network Criteria Performance Reliability Security 6
  7. 7. Performance  # of users  Medium  Hardware  Software 7
  8. 8. Why ? To Share Peripherals       Printers Scanners Hard Disk CD Rom Plotters Tape Backup Reduce Cost 8
  9. 9. Why ? • Enabling Common Administration & Security • Network Applications • Email • Database Service • Groupware 9
  10. 10. Types of networks 1. Local Area Network (LAN) 2. Metropolitan Area Network (MAN) 3. Wide Area Network (WAN) 10
  11. 11. Local Area Network - LAN  A network that connects computers in a limited area such as a school, company, or building.  Consists of a network operating system, networked computers, network interface card, and a communication channel.  LANs are privately controlled w.r.t data processing equipment. 11
  12. 12. Local Area Network - LAN The two popular types of LANs are : 1. Peer-to-Peer. 2. Client / Server. 12
  13. 13. Peer-to-peer LAN 13
  14. 14. Client / Server 14
  15. 15. METROPOLITAN AREA NETWORK (MAN) • MANs connect locations that are geographically located from 5 to 50 kilometres. • They include the transmission of data, voice and television signals through the use of coaxial cables or optical fiber cables as their primary medium of transmission. 15
  16. 16. Wide Area Network - WAN • Covers a large area using a communication channel. • Connects two or more LANs. • Internet is the largest WAN. • WANs use a broad range of communication channel for interconnection that includes switched and leased lines, private microwave circuits, optical fibre, coaxial cable and satellite circuits. However, most WANs implement LAN inter-connectivity via Public Switched Telephone Networks (PSTNs) 16
  17. 17. NETWORK TOPOLOGY • The configurations used to describe networks are sometimes called Network architecture or network topology. The most common network topologies are: - Ring - Bus - Star - Mesh - hybrid 17
  18. 18. Ring network • Data travels around the ring in one direction. • The message knows the destination because each workstation in the ring network has a unique address. • Advantages: - High reliability - Easy expandability - Normally lower cost than star and hybrid networks. 18
  19. 19. Ring network topology 19
  20. 20. Bus Network • Connects all networked devices to a single cable (called the Bus) running the length of the network. • Advantages: - Good reliability, unless the bus itself malfunctions. - Very easy to expand 20
  21. 21. Bus Network Topology 21
  22. 22. Star Network • • • - All devices on the network are connected to a central device that controls the entire network. The central location receives message from a sending node and forwards them to the destination node. Advantages: provides the shortest path between nodes in the network Provides the user with a high degree of central network control Relatively easy to expand the network. Disadvantage: If the central station (hub) malfunctions, the entire network would fail. 22
  23. 23. Star Network Topology 23
  24. 24. Mesh Network • Each node has a direct point to point connection to every other node in the network. • Provides best performance as every node on the network has a direct route to every other node. • Disadvantage: Cost of setting up a mesh network can be very expensive. • N=nodes; no. of links= n(n-1)/2 24
  25. 25. Mesh Network Topology 25
  26. 26. Hybrid Network • Combination of more than one of the network configurations. Example: a bus network may have a ring network as one of its links. 26
  27. 27. LAN Architectures • Together with the appropriate transmission media, the LAN topologies provide the basic physical elements for the design of Local area networks. • Three of the most commonly used LAN architectures that have evolved are: - Ethernet - Token ring - Token Bus 27
  28. 28. Thank You • Kindly give the feedback with your supporting comments to rise for better presentation .. 28

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