1. Network Hardware Devices
Computer networking devices are units that mediate data in a computer
network.
 Networking hardware includes all computers, peripherals, interface cards
and other equipment needed to perform data-processing and
communications within the network
Computer networking devices are also called N/W equipment or
Intermediate Systems (IS).Units which are the last receiver are called hosts

2. List of computer networking devices
1)Common basic networking devices:
 Router
 Bridge
 Switch
 Hub
 Repeater

3.  Routers are devices which connect two or more networks that use
similar protocol.
 A router consists of hard ware and software.Hard ware can be a
computer is specific device.Software consists of special
management program that controls flow of data between networks.
 Routers operate at a network layer of O.S.I model.
 Routers use logical and physical address to connect two or more
logically separate network. They make this connection by
organizing the large network into logical network segment (some
times small sub network or sub nets). Each of these sub nets is
given a logical address. Data is grouped into packets or block of
data.
 Router are used to segment LAN’s that have become so large to
conserve the network bandwidth.
Cont...

4. Advantages of Router:
 They use high level of intelligence to rout data.
 Router allows filtering of data so called smart gateway.
Disadvantages of Router:
 High level of intelligence take more processing time which can effect
performance.
 Routers are very complicated which installation and maintenance difficult.

5. Gateway
Gateways are devices which connect two are more
networks that use different protocols.
 A gateway is used to convert two different
environment, such as Frame Relay Network & an X.25
network. For e.g. a gate way can receive email messages
in one format in convert them into another format.
 Gateway can operate at all seven layer of OSI model.
They are similar in function to routers but they are
more powerful and intelligent devices.
Cont...

6. Disadvantages:
 Since Gateway perform data conversion so they are
slower in speed.
Gateway are very expensive device.

7. Repeater
Repeater are used to take the signal that it receive from the
computers & other devices on the LAN and regenerate the
signal in order for the signal to maintain its integrity while
travelling along a longer media run that is normally
possible.
Repeaters are used within network to extend the length of
communication.
Repeaters work at the physical layer of OSI model.
Repeater do not have any capability of directing network
traffic or deciding what particular route that certain data
should take, they are simply devices that sit on the network
and boost the data signal that they receive.
Cont...

8. Advantages of Repeater
 Repeaters easily extend the length of network.
 They require no processing over head, so very little if any performance
degradation occurs.
Disadvantages of Repeaters
Repeaters can not be used to connect segments of different network types.
They cannot be used to segment traffic on a network to reduce congestion .

9. Bridge
Bridge is an internetworking device used to connect similar
network segments.
When the bridge receives the signals it read address of both
sender and receiver. If the sender is a computer in segment A and
the receiver is also segment A, it would not pass the signals to the
segments B. It will however pass signals if the sender is in one
segment and the receiver in other segment.
Bridge works at the data link layer of O.S.I model
They also use the software to help get the job done.
Cont...

10. A B E F
BRIDGE
C D G H
 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.
Advantages of Bridges
one logical network.
Like repeaters they can connect similar network types with different
Bridge extends network segments by connecting them together to make
cabling.
Disadvantages of Bridges
 Bridge possess information about the data they receive with can slow
performance

11. Hub
Hubs serve as central connection points for LAN’s that
typically embrace the star topology.
A Hub connects all the nodes of a network using twisted pair
cable.
The ports which are available on the hub, provide information
point for the device on the network. computer and devices
are
connected to the hub through network cable to individual
ports.
The more ports on the hub, the more expensive the hub.
These are some hubs which are
I. Passive Hub
II. Active Hub
III. Switch/ Intelligent Hub
Cont...

12. Advantages of Hub
 Hubs need almost no configuration.
 Active hub can extend maximum network media distance.
No processing is done at the hub.
Disadvantages of Hub
 Passive hubs can greatly limit maximum media distance.
 Hubs have no intelligence to filter traffic so all data is send
out on all ports whether it is need or not.

13. Switch
A switch is an internetworking device used to manage bandwidth on a large
network.
Switches divide network into what is known as a virtual LAN or VLAN.
Switches use a combination of software and hardware to switch packet
between computer and other devices on the N/W. This software is the switch
operating system and because switch offer a high density of connection
ports,they can easily replace hubs on the network this means that each
computer on the N/w can be connected to its own port to the switch,When
the comp. are directly connected to the switch,The switch can supply each of
the comp. with a dedicated amount of bandwidth.
For ex:Say users are on a 100 Mbps Ethernet N/W via a switch. Each user can
realize a bandwidth of 100 Mbps and thus have to compute for a bandwidth
the way comp. do on a N/W via a Hub because each port on the switch has a
dedicated 100 Mbps this is why switches are rapidly replacing hubs.
Cont...

14. Switch
Switches also replaced bridges as the internetworking devices for conserving
network bandwidth and expanding LANs into larger corporate internetworks.

15. 2).Some hybrid network devices:
 Protocol Converter
Bridge Router
Digital media receiver

16. Protocol Converter
Protocol Converter is a device used to convert standard or proprietary
protocol of one device to the protocol suitable for the other device or tools
to achieve interoperability.
The protocol conv.can be s/w conv,H/W conv, or an integrated conv.
Depending on the protocols.
Protocol converter include an internal master protocol communicating to
the external slave devices and the data collected is used to update the
internal D/B of the converter.When the external master requests for the
data, the internal slave collects the same from the d/b and send it to the
external master.

17. Digital Media Receiver
A digital media receiver (DMR), also commonly referred to as a media
extender, media streamer, or digital media adapter (DMA), is a home
entertainment device that can connect to a home network to retrieve digital
media files (such as music, pictures, or video) from a personal computer or
other networked media server and play them back on a home theater system
or TV.
Cont...

18. A digital media receiver can connect to the home network
using either a wireless or wired (Ethernet) connection.
A DMR includes a user interface that allows users to
navigate through their digital media library, search for, and
play back media files. Different DMRs are designed to
handle different tasks.
Some DMRs only handle music; some handle music and
pictures; some handle music, pictures, and video; while
others go further to allow internet browsing or controlling
Live TV from a PC with a TV tuner.

19. Bridge Router(Brouter)
A network device that combines the functions of a bridge and
a router in one unit.
Brouters operate at both the network layer for routable
protocols and at the data link layer for non-routable
protocols.
As networks continue to become more complex, a mix of
routable and non-routable protocols has led to the need for
the combined features of bridges and routers.
Cont...

20.  Brouters handle both routable and non-routable features by
acting as routers for routable protocols and bridges for non-
routable protocols.
Bridged protocols might propagate throughout the
network, but techniques such as filtering and learning
might be used to reduce potential congestion.
Brouters are used as connecting devices in the networking
system, so it acts as a bridge in a network and as a router in
an internetwork

21. Other hardware for establishing networks or dial-up
connections
 Multiplexer
 Network Card
 Modem
 ISDN terminal adapter
 Line Driver

22. Modem
A modem (modulator-demodulator) is a device that modulates an
analog carrier signal to encode digital information, and also demodulates
such a carrier signal to decode the transmitted information.
 The goal is to produce a signal that can be transmitted easily and
decoded to reproduce the original digital data.
For e.g. Computer information is stored digitally, Whereas information
transmitted over telephone lines is transmitted in the form of analogue
wave. A modem converts between these two forms.

23. Network Interface Card
.
A Network Interface Card is an expansion card which installs into a comp.
and enables that comp. to physically connect to a Local Area Network.
The most command form of Network Interface Card in current use is the
Ethernet card. Other types of Network Interface Cards include wireless
Network Interface Cards and Token Ring Network Interface Cards.
Network Interface Cards are becoming rare, as most motherboards now
include built-in Network Interfaces
Cont...

24. Every N/w card has a unique 48 bit serial number called a MAC
address, which is stored in a rom carried on the card.Every comp. on
the Ethernet N/W must have a card with a unique MAC address , A
MAC address look similar to this:00:60:08:8F:5A:D9.
The H/W address is used by dynamic host configuraton protocol to
identify a specific host. it is also used by address resolution protocol
and reverse address resolution protocol to map host to IP address.

25. ISDN Terminal Adapter
ISDN Terminal Adapter is a device that connects a terminal to the ISDN
N/W.
The TA therefore fulfills a similar function to the ones a modem has on the
POTS network, and is therefore sometimes called an ISDN modem. The
latter term, however, is partially misleading as there is no modulation or
demodulation performed.
ISDN can create multiple channel on a single line.
It is a device with a high throughput rate.
ISDN concept is the integration of both analog or voice data together with
digital data over the same network

26. Line driver
In electronics, a line driver is an amplifier used to improve
the strength of an analog or digital signal at its source by
driving the input to the transmission line with a higher
than normal signal level.
This increases the quality of a transmission over a long run
of cable.
An example of a line driver is an amplifier used to extend
the range of an digital signal. In mobile audio, use of a
line driver allows an amplifier's gain to be set lower,
reducing low-level noise. Line drivers may also be used to
enhance distortion in guitar amplifiers.

27. Multiplexer
A multiplexer or mux is a device that performs multiplexing; it selects
one of many analog or digital input signals and forwards the selected
input into a single line. A multiplexer of 2n inputs has n select lines,
which are used to select which input line to send to the output.
An electronic multiplexer makes it possible for several signals to share
one device or resource, for example one A/D converter or one
communication line, instead of having one device per input signal.
Schematic of a 2-to-1 Multiplexer. It can be equated to a controlled switch.
Cont...

28. Schematic of a 1-to-2 Demultiplexer. Like a multiplexer, it can be equated to a controlled switch.
On the other end, a demultiplexer (or demux) is a device taking a
single input signal and selecting one of many data-output-lines,
which is connected to the single input.
One use for multiplexer is cost saving by connecting a MUX & a
DMUX together over a single channel.

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