This document discusses several common networking devices and their functions. It describes hubs, switches, bridges, routers, gateways, CSU/DSUs, NICs, ISDN adapters, modems, and firewalls. Hubs broadcast traffic to all ports, wasting bandwidth, while switches only forward frames to their destination port. Bridges operate at the data link layer and routers at the network layer. Gateways perform protocol translation. NICs connect devices to the network. Modems convert digital to analog signals for transmission over phone lines. Firewalls control network access for security.

1. BY ADEEBA KHAN
COMPUTER TECHNOLOGY

2. All but the most basic of networks require
devices to provide connectivity and
functionality

3. Some networking devices
✓ Hubs
✓ Switches
✓ Bridges
✓ Routers
✓ Gateways
✓ CSU/DSU (Channel Service Unit/Data Service Unit)
✓ NICs (Network Interface Card)
✓ ISDN (Integrated Services Digital Network) adapters
✓ Modems
✓ Firewalls

4. HUB
CHEAP
SIMPLE BUT
WASTES
BANDWIDTH

5. H
Network with a Hub
SENDER
RECEIVER

6. H
Network with a Hub
SENDER
RECEIVER

7. H
Network with a Hub

8. How a hub behaves
 Each incoming bit is replicated on all other interfaces
 Simplest and cheapest way to create a network
 Lots of unnecessary traffic
 Security problem

9. A hub may be passive or active :-
 Those which operate below the physical layer is a
passive hub.
 Those which operate at the physical layer is an active
hub

10. Uses of hub
 Hubs are used to create small Home Networks.
 Hubs are used for monitoring the networks.
 Hubs are used in Organizations and Computer Labs
for connectivity.
 It Makes one device or peripheral available throughout
the whole network.

11. Repeater
A repeater is a device
that operates only at
the physical layer
Repeater

12. Repeater connecting two segments of a LAN
Function of a repeater

13. Bridge
 Bridge is a more
intelligent form of Hub.
 Packets are processed
based on MAC address
inside the incoming
packet.
 Bridge is not very useful
for end – computing
devices

15. Switch
Switch is bridge with
more than 2 ports.
More scalable and
practical

16. If a hub capture a list where every host can be reached than it
would be able to send every packet straight to it destination
without expanding the entire network.
 Two layer switch operate at physical and data link layer.
 Three layer switch operates at network, data link and physical
layer.

17. The Switch Table
1 2 3 4 5 6
A B
Interface MAC address
1 AA-AA-AA-AA-AA
2 BB-BB-BB-BB-BB

18. The Switch Table
1 2 3 4 5 6
Interface MAC address
1 AA-AA-AA-AA-AA
3 CC-CC-CC-CC-CC
4 DD-DD-DD-DD-DD
6 BB-BB-BB-BB-BB
B
D
A
C

19. Ways in which Switch work..
Flooding
Forwarding
Filtering
Broadcasting

20. Flooding :-
Flooding is performed when the switch has no entry for the
frame's destination MAC address. When a frame is flooded, it is
sent out every single port on the switch except the one it came in
one.
Forwarding :-
Forwarding is performed when the switch does have an entry for
the frame's destination MAC address. Forwarding a frame means
the frame is being sent out only one port on the switch.

21. Filtering :-
Filtering is performed when the switch has an entry for both
the source and destination MAC address, and the MAC table
indicates that both addresses are found off the same port.
Broadcasting :- There is one other frame type that is sent out
every port on the switch except the one that received it, and
that's a broadcast frame, Broadcast frames are intended for all
hosts, and the MAC broadcast address is ff-ff-ff-ff-ff-ff .

22. Router
Routes packets based on
their logical addresses
(host-to-host
addressing)
A router normally
connects LANs and
WANs in the Internet
and has a routing table
that is used for making
decision about the route.

23. The routing tables are normally dynamic and are updated
using routing protocols.

24. Need of Routers
packet
LAPTOP INTERNET SEARCH ENGINE

25. Gateway
Any device that
translates one data
format to another is
called a gateway.
Gateways, also
called protocol
converters, can operate
at any network layer.

26. A gateway takes an application message ,reads it and
interpret it .
Gateway can provide security.
It filter unwanted application layer messages.
 The activities of a gateway are more complex than that
of the router or switch as it communicates using more
than one protocol.

27. Each device work on different layer

28. OTHER NETWORK DEVICES

29. NIC (network interface card)
NIC are devices that enable
computers to connect to the
network.
It is both a physical layer and
data link layer device
It allows users to connect to
each other either by using
cables or wirelessly.

30. How NIC works ?
 A computer or device on a network can be reached by its
MAC(media access control) address through the NIC
card.
 Every Ethernet network card has a unique 48-bit serial
number called a MAC address which is stored in ROM
carried on the card.
 The MACs on the network are used to direct traffic
between the computers

31. The Ethernet address is 6 bytes (48bits),normally written in
Hexadecimal notation with a colon between the bytes.
Example
06:01:02:01:2C:4B
Source address is unicast address –the frame comes from only
one station .
Destination address ,however can be unicast , multicast, or
broadcast.
LSB of first byte defines the type of address. If the bit is 0 ,the
address is unicast otherwise multicast .
Broadcast is a special case of multicast where all bits are 1.

32. Modem
A modem, short for
modulator/demodulator, is
a device that converts the
digital signals generated
by a computer into analog
signals that can travel over
conventional phone lines.

33. The modem at the receiving end converts the signal
back into a format the computer can understand.
Modems can be used as a means to connect to an ISP
or as a mechanism for dialing up to a LAN.

34. FEATURES OF MODEM
Modulated Signals
Data Compression
Error Correction
Flow Control

35. Modulated signal
The essential function of a modem is to create an easily
transmitted and decoded signal that allows digital data to be
sent from place to place without the loss of information.
Data Compression
To reduce the amount of time it takes to send data and to cut
down on the amount of error in the signal, modems need to
employ data compression. Data compression techniques
reduce the size of the signal needed to send the required data.

36. Error Correction
When information is transmitted between modems, it can
sometimes be damaged -- meaning that parts of the data are
altered or lost. To get around this, modems use error correction.
Flow Control
Individual modems send information at different speeds. It's
necessary for faster modems to slow down so that slower
modems can catch up, otherwise the slower modem will
receive more data than it can process.

37. ISDN
Integrated Services Digital Network (ISDN) is a remote
access and WAN technology .
ISDN offers greater speeds than a modem .
Integrated services refers to ISDN's ability to deliver at
minimum two simultaneous connections, in any combination
of data, voice, video, and fax, over a single line. Multiple
devices can be attached to the line, and used as needed.

38. CSU/DSU
 A Channel Service
Unit/Digital Service Unit
(CSU/DSU), is a device
that converts the digital
signal format used on LANs
into one used on WANs.
 The CSU/DSU sits between
the LAN and the access
point provided by the
telecommunications
company.

39. Firewalls
 A firewall controls access to
your organization’s network.
 Firewalls can be implemented
through software or through a
dedicated hardware device

40. Sources
 http://www.pearsonhighered.com/samplechapter/078
9732548.pdf
 Data Communications and networking
by Behrouz A Forouzan (Tata McGrawHill)
 http://www.wikiforu.com/2013/04/hub-types-
applications-in-network.html
 https://www.youtube.com/watch?v=Xmwmezk75Tk

41. THANKYOU