about Network Topology & Networking Devices included in MSBTE syllabus of SY computer subject Chapter 2 in CNE

2. Topology
• The way of connecting the computers is called as
‘Topology’
• The way in which different systems and nodes are
connected and communicate with each other is
determined by topology of the network.
• Topology can be physical or logical. Physical
Topology is the physical layout of nodes,
workstations and cables in the network; while
logical topology is the way information flows
between different components.

4. Selection Criteria for topologies
• Different network topologies have its own advantages and
disadvantages. So, following factors are considered while
selecting a topology:
1.Cost
2.Number of users
3.Security
4.Reliability
5.Scalability
6.Bandwidth capacity
7.Ease of installation
8.Ease of troubleshooting

5. Type of Topologies
• Following are the six types of topology
1.Bus Topology
2.Ring Topology
3.Star Topology
4.Mesh Topology
5.Tree Topology
6.Hybrid Topology

6. Bus Topology

7. Bus Topology
• Used when a network installation is simple or
temporary.
• Just one cable, with no active electronics to amplify the
signal this make bus a passive topology.
• Long cable called bus is used as a backbone.
• When one comp sends signal; all the comp receives the
information, but one with address matches can encode
& accepts the information.
• Speed in slow b/c only one comp can send msg at a
time. All other comps must wait
• Requires proper termination at both ends of cable.

8. Advantages & Disadvantages
• Advantages
1. Easy to understand,
install, & use for small
n/w.
2. Cabling cost is low.
3. Easy to expand.
• Disadvantages
1. Heavy traffic can not
handle.
2. Connectors are
required to expand
bus so signals can be
attenuates.
3. Cable break all the
network activity will
stop.

9. Ring Topology

10. Ring Topology
• Each comp is connected to next comp with last
one connected to first.
• Used in high performance n/w where large
bandwidth is necessary e.g. time sensitive
features video & audio.
• The msg. flow around the ring in one direction.
There is no termination.
• Some ring n/w do token passing.
• Each comp receives msg. but only dest comp can
read msg. if address matches.

11. Advantages & Disadvantages
• Advantages
1. Every comp having
same capability.
2. Fair sharing of
network.
• Disadvantages
1. Failure of one PC affect
whole network.
2. Difficult to trouble
shooting.
3. Adding or removing is
more difficult.

12. Star Topology

13. Star Topology
• All the cables run from comp to central
location device called hub.
• Used in concentrated network, where end
point is directly reachable from central
location.
• Each comp on star n/w communicates with a
central hub that resend msg.
• Hub broadcast msg while switch sends msg. to
dest comp.

14. Advantages & Disadvantages
• Advantages
1. Easy to modify & Add
new comp without
disturbing others.
2. Central device is best
place to find out faults.
3. A comp failure do not
affect all.
4. Different types of cables
can be used in same
n/w.
• Disadvantages
1. If central hub fails whole
n/w fails.
2. Many star n/w required
devices to rebroadcast
or switch the n/w traffic.
3. Cabling cost is more.

15. Mesh Topology

16. Mesh Topology
• Every device has dedicated point to point link to
every other device.
• Dedicated means that the link carries traffic only
between two devices it connects.
• Also called as complete topology.
• Does not have traffic congestion problem.
• Links are not being shared, so media access
control protocol is not required.
• Advantages in terms of data security.

17. Advantages & Disadvantages
• Advantages
1. Dedicated links
eliminates traffic
problems.
2. Failure of one comp
does not affect to all
3. Provide security &
privacy
4. Point to point links make
fault detection easy.
5. MAC protocol do not
need.
• Disadvantages
1. Installation &
reconfiguration is
difficult
2. More cabling cost
3. More h/w requirement
4. Suitable for small n/w.

18. Tree Topology

19. Tree Topology
• Variation of star.
• All comps are not attached to central hub
majority of them are connected to secondary
hub which are connected to central hub.
• Central hub is active hub contains repeater.
• repeater amplify the signals.
• Secondary hub may be active or passive.

20. Advantages & Disadvantages
• Advantages
1. Allows more devices
to be attached to a
single hub & signals cal
travel more distance.
2. Network can be isolate
& Priorities
communication of diff
comp.
• Disadvantages
1. Central hub fails the
system breaks down.
2. Cabling cost is more.

21. Hybrid Topology
• Two or more basic topologies are combine
together
• Practical n/w generally poses hybrid topology.

22. Hybrid Topology

23. Network Control devices
Need of Network Control devices
1. Computers / LANs do not work in isolation.
They are connected to one another or
internet. For such connection we need
Network Control devices.
2. Connecting devices can be work in diff layers
of n/w.
3. Without Network Control devices
connections can not be possible.

24. Network Control devices
• Following are the types of Network Control
Devices.
1. Repeater
2. Hubs
3. Bridges
4. Switch
5. Routers
6. Gateways
7. Modems

25. 1.Repeater
• A repeater (or regenerator) is a device which
operates only in the physical layer.
• All transmission media weaken the
electromagnetic waves that travel through them.
• A repeater receives a signal and before it
becomes too weak or corrupted, regenerates the
original bit pattern.
• Original signals is duplicated, boosted, to its
original strength.
• It has no filtering capacity.

26. 1.Repeater

27. Advantages & Disadvantages
• Advantages
1. Can regenerate
desired information
2. Reduce effect of noise
3. Can extent the n/w
4. Reduce no. of errors
• Disadvantages
1. Can not connect two
LANs only two
segments of LAN
2. No filtering capability
3. Operate on physical
layer

28. 2. Hubs

29. 2. Hubs
• It operates only in the physical layer.
• Hub is multi-point repeater. A signal received
at any port on the hub is retransmitted on all
other ports.
• A big advantage of the hub is to share the
different applications without the individual
access and can share the resources with the
help of hub.
• Types of Hub: 1. Passive 2. Active 3. Intelligent

30. 2. Hubs
• Passive Hubs:
1. Combines the signals of a network segments. No signal processing or
regeneration
2. Reduce cabling distance b/c it does not boost signals.
3. Each comp receives signals sent by the hub
• Active Hubs:
1. Like passive hubs but have electronic components for regeneration and
amplification of signals. Distance bet two devices can be increase.
2. Drawback is amplifies noise with main signals. Expensive than passive
hubs

31. 2. Hubs
• Intelligent Hubs:
1. Perform some n/w mgmt & intelligent path
selection.
2. All transmission media segment can be
connected permanently b/c each segment
will be used only when a signal is sent to a
device.

32. 3. Bridges

33. 3. Bridges
• It operates on physical & data link layer.
• A bridge is a type of computer network device
that provides interconnection between two
segments networks that use the same protocol
i.e. used to connect 2 LAN.
• A Bridge provides packet filtering at data link
layer, meaning that it only passes the packets to
the segment have a destination node.
• The diff bet repeater & Bridge is bridge is having
filtering capability.

34. 3. Bridges
• Types of Bridge
1. Transparent Bridge
 Filtering Frames
 forwarding
 Blocking
2. Routing Bridge

35. 4. Router

36. 4. Router
• It operates at physical, data link and network layers of OSI
model.
• Routers are devices which can intelligently route network
traffic in different ways.
• Routers are more intelligent than bridges. They consist of a
combination of hardware and software. The hardware can
be a network server, a separate computer or special device.
• The software in a router is the operating system and the
routing protocol.
• Routers use logical and physical addressing to connect two
or more logically separate networks.

37. 5. Switch

38. 5. Switch
• It Switch works at Data link layer and Network layer of OSI
model.
• Switch is used in star topology.
• When centralized management of nodes is required Switch
is used.
• A switch is device that provides a central connection point
for cables from workstations, servers and peripherals.
• A switch is a small hardware device that joins multiple
computers together within one Local Area Network (LAN).
• Switch has a buffer for each link to which it has connected.
• Two types are:1. Store & forward, 2.Cut Through switch

39. 6.Gateways

40. 6.Gateways
• Gateway works at all 7 layers of OSI Model.
• Any device that translates one data format to
another is called a gateway. Only the data format
is translated. Data is kept as it is.
• When networks which are using different
protocols need to be connected to each other, we
need a Gateway between them.
• A network gateway can be implemented
completely in software, completely in hardware,
or as a combination of both.

41. 7.Modem

42. 7.Modem
• Modem is an abbreviation for Modulator and Demodulator.
• Modems are used for data transfer from one computer
network to another computer network through telephone
lines.
• The computer network uses digital signal, while analog
signal is used for carrying massages across phone lines.
• Modulator converts digital signal into analog signal at
transmitting end.
• Demodulator converts analog signal into digital signal at
receiving end.

43. Network Software
• Network software are used for
communication applications like email, instant
message, teleconferencing and video
conferencing.
• Following are the two example of Network
Software
1.NIC Device Driver
2.Client Server Software ex: - 1) Telnet 2) FTP

44. 1.NIC Device Driver
–Functions of NIC include:
• Provide physical link or connectivity between
computer and the network physical medium.
• Prepare data from computer for network
cable.
• Send data to another node in network.
• Control flow of data between computer and
physical medium.

45. 2.Client Server Software
1.Telnet
•TELNET stands for Telecommunication Network.
•This is a network protocol used on Internet or LAN
•It is used to provide a bi-directional interactive text-oriented
communication.

46. 2.FTP
•The File Transfer Protocol (FTP) is a standard network protocol
used to transfer computer files between a client and server on a
computer network.
• FTP is built on a client-server model architecture and uses
separate control and data connections between the client and
the server.