Networking Devices and Networking Topologies hub, router, switch, multiplexer, modem, repeater, bus topology, star topology, ring topology

1. Computer Networking
Networking Devices
Networking Topologies

2. Networking Devices
• Hubs
• Switch
• Router
• Modem
• Repeater
• Multiplexer
Networking Topologies
• Bus Topology
• Star Topology
• Ring Topology

3. Networking Devices
 Networking=Working together
 The devices that help the network to be
linked to each other
 Objective of helping share data and/or
hardwares or softwares

4. Hubs
 connects two or more devices without having to connect to
each other directly
 uses twisted pair cable
 basic function: forward the data it received from a connected
device to all other connected devices regardless of whether the
data is destined for the device.
 creates bottleneck on larger busy networks
 comes in variety of shapes and sizes:
workgroup hubs: consists of 5-8 ports
high density devices: consists up to 32 ports

5. Hubs: how they work!!

6. Hubs
Are of three types:
1. Passive Hubs:
provides a pathway for signals to travel
does not need power to operate
2. Active Hubs:
provides a pathway for signals to travel
regenerates the signals before passing it on
requires power to operate
3. Intelligent Hubs:
performs all the jobs of active and passive
helps in troubleshooting by pointing the actual location
of the problem

7. Switch
• forwards data packages to only the destined device
• checks the MAC address found in the NIC to do so
• by forwarding the data to only the destined device, it reduces the number of
collision in the network
• uses three methods to deal with the data’s as they arrive:
1. Cut through:
o Begins to forward the package as soon as it arrives
o No error checking performed
o Packet is moved quickly
2. Store and forward
o Waits to receive the entire package before forwarding it
o Basic error checking is performed
3. Fragment Free
o Built on the speed advantage of cut through
o Forwards package in fragments

8. Switch: how it works!!

9. Router
• increasingly common sight in any networking environment
• most commonly used to connect a home computer to an ISP
• used to create large networks by joining two network segments
• derives it’s name from the fact that it can route data from one
network to another
• when it receives a packet of data, it reads the header of the
packet to determine the destination address
• when address is determined, it looks in it’s routing table to see
whether it knows how to reach the destination
•If it does know how to reach the destination it then forwards the
data to the next hop on the route
•The next hop could be the final destination or another router

10. Router: how it works!!

11. Modem
• short for modulizer-demodulizer
• converts data being used by a computer into an audio signal
that is able to be transmitted over a phone line
• When the signal gets to its intended destination, another
modem then reconverts the signal back into data
• the process of converting data into audible sound is known as
modulation
• converting it back to the data is known as demodulation
• Modems provide a relatively slow method of communication
• the fastest modem available on the market today has a
maximum speed of 56Kbps
• unsuitable for downloading large files.

12. Modem: how it works!!

13. Repeaters
• send signals over long distances
• function of a repeater is to receive incoming signals or a packet of data,
regenerate the signals to their original strength and retransmit them
• helps computers maintain stronger wireless signals by taking in signals from
routers and remitting them
• primary advantage of using a wireless repeater is that it can improve
wireless signal strength without having to move a computer or router
• further a computer is from the wireless router it connects to, the weaker its
wireless signal will tend to be
• Placing a wireless repeater at some point between a computer and the
router it connects to can enable the computer to receive a stronger signal
• Another benefit of using a wireless repeater is that it can help you reduce
the impact of obstructions that may impact your wireless connection
• Physical objects can weaken wireless signals so we should place a repeater
in a location where few objects rest between it

14. Multiplexer
• accepts multiple inputs and allows only one to go through as
an output
• receiving end accepts this complex signal and reconverts it
into its individual components
• multiplexing is used in both digital and analog data
transmission
• provides great cost advantages, since it reduces the need for
additional wires and/or communication channels but, the initial
cost of setting it up is expensive
• multiplexing can slow down the communication process, since
shifting from one frequency to another causes time delays
• another disadvantage of it requires constant source of
electrical power to operate

15. Multiplexer
Multiplexers are of three types:
1. Frequency division multiplexing :
• divides a single bandwidth into various different frequencies so it can
be used by multiple users
• each different frequency carries a separate signal at the same time
2. Time division multiplexing :
• allows multiple signals to travel across the same transmission
channel
• but allocates different time slots to each.
3. Dense wavelength division multiplexing :
• is a version of frequency division multiplexing
• it sends colored lasers to transmit data over the same bandwidth

16. Network Topologies
• network layout of connected devices
•Arrangement of network
•Layout of connected device

17. Bus topology: the setup!!

18. Bus topology
Advantages
 Easy to add and remove nodes
 Requires small amount of cable compared to other
topologies so is less expensive and easier to setup and
troubleshoot.

19. Bus topology
Disadvantages
 A failure in the central line means the whole network will
go down.
 Only one route for data to take so will performance will
decrease as more data is transmitted.

20. Ring Topology: the setup!!

21. Ring Topology
Advantages
 As all the data can only travel in one direction the
transmission of messages is simple and high rates can
be achieved.
 There is no dependence or need of a central computer
or mainframe.

22. Ring Topology
Disadvantages
 If one node or line fails then data cannot continue to be
transmitted between all the rest of the nodes in the
network.
 Harder to add new nodes into the system, requires the
network to be disrupted.

23. Star Topology: its setup!!

24. Star Topology
ADVANTAGES
 More secure connection as data is sent directly between
nodes (unlike ring networks)
 A failure of the cable will only affect one node, hence faults
are easier to pinpoint.
 Easy to add new nodes without any disruption

25. Star Topology
DISADVANTAGES
 Requires and is dependant upon a central computer.
 Requires more cable and is therefore more expensive to
setup.