Computer Network

1. Dinesh Maharjan, 2022
Data Communication
Instructor: Dinesh Maharjan
2022

21. • Arrangement of computer in network.
• Physical topology: Way nodes are connected
in network
• Logical topology: Way data travels through
network from one node to another.
• Bi-directional, Unidirectional, MAC
addressing, IP addressing.
Network Topology

22. • Computers are connected with single co-axial
cable called backbone.
• The cable is terminated at the ends.
• Data is broadcasted to this cable.
• Data travels bi-directionally.
• Can go to all the nodes in network but
received by only one end node.
• Terminator destroys the data it receives.
Bus Topology

23. Bus Topology

24. Bus Topology

25. • Cheap easy to implement
• Requires less cable
• No network specialized network equipment
should be used.
Bus Topology Advantages

26. • Break in cable takes down entire network.
• Can be used for small network.
• Network disruption when computers are
added or removed.
• Collision of data can occur.
• Difficult to detect the failure of network.
Bus Topology Dis-advantages

27. • Computers are connected circularly through
single cable
• Some type of data called token keeps
revolving through the ring.
• Any Computer needs to send the data gets
the token and send data through it.
• Data travels unidirectionally anti-clockwise.
• Only one node can transmit data at a time.
• Each node acts as repeater.
Ring Topology

28. Ring Topology

29. • No collision of data
• Easier to detect defective node.
• It can extend to long distance as each node
can regenerate the data.
Ring Topology Advantages

30. • If cable breaks down, entire network does not
work.
• Expansion of the network cause disruption.
• Requires more cables and equipment's.
• So expensive.
Ring Topology Disdvantages

31. • Computers are connected to center node
either hub or switch.
• Each device needs a cable.
• Point to point connection between hub and
computers.
• Widely used in modern network.
Star Topology

32. Star Topology

33. • Very easy to connect and manage the
network.
• Easy to extend the network.
• Cable failures affects only single user.
• Easy to locate the failure.
Star Topology Advantages

34. • If hub or switch fails, entire network comes
down.
• Expensive as hub or switch is used.
• Requires more cable.
Star Topology Dis-advantages

35. • Two or more star topology is connected
together.
• Can expand to large distance.
Tree Topology

36. Tree Topology

37. • Point to point connection between each
nodes in the network.
Mesh Topology

38. • No disruption on network expansion.
• None need to use switching to connect.
• Easy to find failure.
Mesh Topology Advantages

39. • Not practical.
• Expensive as redundant cables are used.
• No. of cables grows quadratically to the
number of nodes.
• N(n-1)/2.
Mesh Topology Dis-advantages

76. • Wireless Fidelity is also known as wireless
LAN.
• Connects mobile devices to wired network,
internet and to each other.
• Uses radio technology to transmit and
receive data at high rate..
• Frequency range is 2.4GHz to 5 GHz
WiFi

93. • Noise occurs when unwanted signal couples
with data signal.
• Examples of noise are crosstalk, echo,
singing
Noise

94. • In echo, sender receives same signal or data
that was sent through transmission channel
after some time.
• It occurs due to difference in impedance of
communication channel segments.
• Singing is uncontrolled echo that is received
by sender or receiver continuously.
• Crosstalk is occurs when two media are
close enough to interfere.
• Twisting of wires avoids crosstalk.
Noise

102. • Server contains crucial data, it must be
secured.
• Many servers should be maintained to
provides services to large users.
• It helps to provide reliable services.
• Servers should be very powerful.
• Expensive
Client Server