This Presentation will helps to learn the basic knowledge in computer network devices along with different usage of each.

1. Networking Devices
S.P. Siddique Ibrahim, AP/CSE
Kumaraguru College of Technology
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2. Internetworking devices
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Increasing power and complexity
Hubs
Bridges
Switches
Routers

3. 3
Why Interconnect?
•To separate / connect one corporate division with another.
•To connect two LANs with different protocols.
•To connect a LAN to the Internet.
•To break a LAN into segments to relieve traffic congestion.
•To provide a security wall between two different types of users.
•To connect WLAN to LAN

4. 4
Introduction
Many times it is necessary to connect a LAN to another LAN or
to a WAN.
Computers within a LAN are often connected using a hub
LAN to LAN connections are often performed with a bridge.
Segments of a LAN are usually connected using a switch.
LAN to WAN connections are usually performed with a router.

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Hubs
Hubs are simple network devices, and their simplicity is
reflected in their low cost.
A hub interconnects two or more workstations into a
local area network.
They provide everything needed to create a small
network.
When a workstation transmits to a hub, the hub
immediately resends the data frame to all connecting
links.
Hubs expand one Ethernet connection into many. For
example, a four-port hub connects up to four machines

6. Simple device Hub
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7. Workstation Hub
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8. Hubs

9. Most hubs are referred to as either active or passive.
Active regenerate a signal before forwarding it to all
the ports on the device and requires a power supply.
 Small workgroup hubs normally use an external
power adapter, but on larger units the power supply is
built in.
Passive hubs, which today are seen only on older
networks, do not need power and they don’t regenerate
the data signal.
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10. Broadcasting
The method of sending data to all systems regardless of the
intended recipient is referred to as broadcasting.
On busy networks, broadcast communications can have a
significant impact on overall network performance
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Switches
A switch is a combination of a hub and a bridge.
It can interconnect two or more workstations, but like a bridge, it
observes traffic flow and learns.
When a frame arrives at a switch, the switch examines the
destination address and forwards the frame out the one necessary
connection.
switches are far more efficient than hubs

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Switches
It looks at the Media Access Control (MAC) addresses of the
devices connected to it to determine the correct port.
A MAC address is a unique number that is stamped into every
NIC.
By forwarding data only to the system to which the data is
addressed, the switch decreases the amount of traffic on each
network link dramatically

13. switch
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14. Corporate switch connection
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15. Bridge
Bridges are networking devices that connect networks.
Sometimes it is necessary to divide networks into subnets to
reduce the amount of traffic on each larger subnet or for
security reasons.
 Once divided, the bridge connects the two subnets and
manages the traffic flow between them.
Today, network switches have largely replaced bridges
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16. Functions of Bridge
A bridge functions by blocking or forwarding data, based on
the destination MAC address written into each frame of data.
If the bridge believes the destination address is on a network
other than that from which the data was received, it can
forward the data to the other networks to which it is
connected. If the address is not on the other side of the
bridge, the data is blocked from passing.
Bridges “learn” the MAC addresses of devices on connected
networks by “listening” to network traffic and recording.
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17. Bridge Device
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Bridge
A bridge connects networks and forwards frames from
one network to another.
BRIDGE
A B
C D
E F
G H
PORTS

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Selective Forwarding
 If A sends a frame to E - the frame must be forwarded by the
bridge.
 If A sends a frame to B - there is no reason to forward the
frame.
BRIDGE
A B
C D
E F
G H

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Workstations connected to a shared segment of a LAN

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Workstations connected to a dedicated segment of a LAN

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A Switch with Two Servers Allowing Simultaneous Access to
Each Server

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A server with two NICs and two connections to a switch

24. Physical Approach
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Bridge Database
 The bridge needs a database that contains
information about which hosts are on which
network.
 The realistic options are:
The system administrator can create and maintain
the database.
The bridge can acquire the database on the fly.
Hard to add
new
computers
Some loss of efficiency

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Bridge interconnecting two identical LANs

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A bridge interconnecting two dissimilar LANs

28. Router
Routers are an increasingly common sight in any network
environment, from a small home office that uses one to
connect to an Internet service provider (ISP) to a corporate
IT environment where racks of routers manage data
communication with disparate remote sites.
Routers make internetworking possible.
Routers are network devices that literally route data around
the network.
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Routers
Thus, routers are often called “layer 3 devices”. They operate at
the third layer, or OSI network layer, of the packet.
Routers often incorporate firewall functions.
An example of a router’s operation is shown on the next slide.

30. By examining data as it arrives, the router can determine the
destination address for the data; then, by using tables of
defined routes, the router determines the best way for the
data to continue its journey.
Unlike bridges and switches, which use the hardware-
configured MAC address to determine the destination of the
data, routers use the software-configured network
address(IP) to make decisions.
This approach makes routers more functional than bridges or
switches.
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33. 33

34. 34

35. 35

36. Switches vs routers
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 Switches are considered layer-two devices, using MAC addresses to forward frames to
their proper destination.
 Routers, layer-three devices, are much more complex, using microprocessor-based
circuitry to route packets between networks based on their IP address.
 Routers provide the following services: route discovery; selection of the best route to
a destination; adaptation to changes in the network; translation from one technology to
another, such as Ethernet to token ring; packet filtering based on IP address, protocol,
or UDP/TCP port number; and connection to a WAN.

37. Bridges vs Routers
Bridge: A bridge is a
device that connects
two segments of the
same network. The two
networks being
connected can be alike
or dissimilar.
Bridges are protocol-
independent. They
simply forward packets
without analyzing and
re-routing messages.
Router: A router is a device that
connects two distinct networks.
Routers are similar to bridges,
but provide additional
functionality, such as the
ability to filter messages and
forward them to different
places based on various
criteria.
The Internet uses routers
extensively to forward packets
from one host to another.
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38. Gateways
The term gateway is applied to any device, system, or
software application that can perform the function of
translating data from one format to another.
The key feature of a gateway is that it converts the format of
the data, not the data itself to another network.
The border device in a network act like a gateway.
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40. Modems
Modem is a contraction of the terms modulator and
demodulator.
Modems perform a simple function: They translate digital
signals from a computer into analog signals that can travel
across conventional phone lines.
The modem modulates the signal at the sending end and
demodulates at the receiving end. Modems provide a
relatively slow method of communication.
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42. 42

43. Internal modem
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44. Network Interface Cards (NICs)
NICs—sometimes called network cards—are the
mechanisms by which computers connect to a network.
NICs come in all shapes and sizes, and they come in prices to
suit all budgets.
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45. PCMCIA NIC & A built-in network
interface on a laptop system.
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46. An expansion NIC.
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47. Transceivers
The term transceiver does not necessarily describe a separate
network device but rather an integrated technology
embedded in devices such as network cards.
 In a network environment, a transceiver gets its name from
being both a transmitter and a receiver of signals, such as
analog or digital.
The transceiver is responsible to place signals onto the
network media and also detecting incoming signals traveling
through the same cable.
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48. Repeaters:
As signals travel along a network cable (or any other medium
of transmission), they degrade and become distorted in a
process that is called attenuation.
 If a cable is long enough, the attenuation will finally make a
signal unrecognizable by the receiver.
A Repeater enables signals to travel longer distances over a
network. Repeaters work at the OSI's Physical layer. A
repeater regenerates the received signals and then
retransmits the regenerated (or conditioned) signals on other
segments.
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51. Booster
A WiFi repeater or extender is used to extend the coverage
area of your WiFi network. It works by receiving your
existing WiFi signal, amplifying it and then transmitting the
boosted signal. With a WiFi repeater you can effectively
double the coverage area of your WiFi network - reaching
far corners of your home or office, different floors, or even
extend coverage to your yard.
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52. What’s the difference between a WiFi
booster, repeater, or extender?
wiFi boosters, repeaters, and extenders are mostly the same
thing - devices to improve WiFi coverage. There isn’t a
clearly defined difference between devices that
manufacturers describe as “repeaters” and devices described
as “extenders”.
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53. Firewalls
A firewall is a networking device, either hardware or
software based, that controls access to your organization’s
network.
This controlled access is designed to protect data and
resources from outside threat.
To do this, firewalls are typically placed at entry/exit points
of a network.
For example, a firewall might be placed between an internal
network and the Internet. After the firewall is in place, it can
control access in and out of that point.
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54. Hardware configuration
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56. Software
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Network Servers
Network servers provide the storage necessary for LAN
software.
They are usually the focal point for the network operating
system.
Increasingly, network servers are functioning as bridges,
switches, and routers. By adding the appropriate card, a server
can assume multiple functions.

59. Network Devices Summary
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60. Contd.,
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Routers (really specialized computers)
The device that connects a LAN to a WAN or a WAN to a WAN
(the INTERNET! – uses IP addresses).
A router accepts an outgoing packet, removes any LAN headers
and trailers, and encapsulates the necessary WAN headers and
trailers.
Because a router has to make wide area network routing
decisions, the router has to dig down into the network layer of
the packet to retrieve the network destination address.

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Connections (in general)
Bridges for LANs and hubs.
Switches for LANs and workstations.
Routers for LANs and WANs (the Internet).

63. Linksys Router for Home Network
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64. The OSI Reference Model
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Network
Layer
Data Link
Layer
Physical
Layer
Application
Layer
Presentation
Layer
Session
Layer
Transport
Layer
Network
Layer
Data Link
Layer
Physical
Layer
Application
Layer
Presentation
Layer
Session
Layer
Transport
Layer

65. The Physical Layer Connection
65
Network
Layer
Data Link
Layer
Physical
Layer
Application
Layer
Presentation
Layer
Session
Layer
Transport
Layer
Network
Layer
Data Link
Layer
Physical
Layer
Application
Layer
Presentation
Layer
Session
Layer
Transport
Layer
SpecifiesSpecifies
electricalelectrical
connectionconnection

66. The Physical Layer Connection
66
Network
Layer
Data Link
Layer
Physical
Layer
Application
Layer
Presentation
Layer
Session
Layer
Transport
Layer
Network
Layer
Data Link
Layer
Physical
Layer
Application
Layer
Presentation
Layer
Session
Layer
Transport
Layer
Hub
AmplificationAmplificationRegenerationRegeneration

67. The Data Link Connection
67
Network
Layer
Data Link
Layer
Physical
Layer
Application
Layer
Presentation
Layer
Session
Layer
Transport
Layer
Network
Layer
Data Link
Layer
Physical
Layer
Application
Layer
Presentation
Layer
Session
Layer
Transport
LayerDelineationDelineation
ofof
DataData
ErrorError
DetectionDetection
AddressAddress
FormattingFormatting

68. 68
Network
Layer
Data Link
Layer
Physical
Layer
Application
Layer
Presentation
Layer
Session
Layer
Transport
Layer
Network
Layer
Data Link
Layer
Physical
Layer
Application
Layer
Presentation
Layer
Session
Layer
Transport
Layer
Bridge
& Switch
The Data Link Connection

69. The Network Layer Connection
69
Network
Layer
Data Link
Layer
Physical
Layer
Application
Layer
Presentation
Layer
Session
Layer
Transport
Layer
Network
Layer
Data Link
Layer
Physical
Layer
Application
Layer
Presentation
Layer
Session
Layer
Transport
Layer
End to endEnd to end
routingrouting

70. The Network Layer Connection
70
Network
Layer
Data Link
Layer
Physical
Layer
Application
Layer
Presentation
Layer
Session
Layer
Transport
Layer
Network
Layer
Data Link
Layer
Physical
Layer
Application
Layer
Presentation
Layer
Session
Layer
Transport
Layer
Router