The document discusses various network connecting devices: - Network Interface Cards (NICs) connect computers to external networks and require proper installation including setting parameters, configuration, and interfacing. - Hubs connect multiple nodes through a single device but reduce bandwidth by broadcasting all data to all ports. Switches improve on hubs by only sending data to relevant ports. - Bridges and routers segment networks and determine the best path to send data between different network segments.

1. NETWORK
DEVICES

2. NETWORK CONNECTING DEVICES
 NIC
 Hub
 Switch
 Repeaters
 Multiplexer
 MODEM
 Router
 Bridges
 Gateways
 Firewall

3. NIC (NETWORK INTERFACE CARD)

4. NIC (NETWORK INTERFACE CARD)
• The NIC used to connect the computer to external network.
• It would normally have the PCI connector (Edge connector) to
connect to one of the PC expansion slots .
• An RJ-45 connector to connect to external Ethernet .
• Almost all the NICs have LED indicators showing the network
connectivity.
• NIC are also called Network Adapters and connecting them in a
network their installation and configuration is very important.
For proper installation of NIC, one needs to pass through three
phases:
• Setting
• Configuration
• Interfacing

5. INSTALLATION OF NIC
 Setting: Before connecting NIC it needs settings of
particular parameters like IRQ, I/O Address. IRQ is
basically interrupt request lines that carry a signal from
a device to processor each device in PC must have
unique IRQ number.
 Configuration of NIC: It involves both hardware and
software configuration. Configuring these hardware and
software configurations the next point comes is
interfacing.
 Interfacing: Once the setting of parameters and
configuring of card is done, it is ready for interfacing
After proper connection you need to install a standard
driver for it.

6. HUB
Hubs are used to connect two or more computers. However we can
connect it without hub but for connecting more than 2 devices we
need hub to allow proper data communication within a network
HUB ARCHITECTURE
A hub looks like a box with ports for LAN nodes to plug in. So most
important part of hub is ports used for connecting network nodes

7. HUB
• Hub is a network connecting device used to connect multiple
nodes of a network through a single device.
• A hub connects all the nodes of network using Twisted pair
cables.
• In hub signals received by one port are transmitted to all other
ports, and vice versa.
• All the nodes connected through hub can listen each other.
• The advantage of using hub is low cost and easy integration.
• The disadvantage is reduce bandwidth and data security.
The reduction in bandwidth comes because all workstations are in
same collision domain. If 2 or more workstations try to transmit
data at same time can result in collision. As a result available
bandwidth of Ethernet network is reduced.

8. TYPES OF HUB
 Passive Hubs: Passive hubs are ones which does not provide any
additional feature except for working just as an interface between the
topology. These types of hubs do not help in rectifying/enhancing the
signals. It simply receives signals on input port and broadcasts it on output
ports.
 Active Hubs: These type of hubs takes participation in data
communication within a LAN network. It comes with various features, such
as receiving the signal and storing it for sometime before forwarding it,
helps transmitting data according to priority highest priority data the lower
one. It also rectify/enhance signal before forwarding.
 Intelligent Hubs: These add some more features than active hubs. It
provide all features of passive and active hub. It also provides features,
which helps in managing the network resources effectively and efficiently. It
helps in improving performance of a network. It helps in finding out where
the problem persists. It determines the exact cause of fault. They can
device that which packet goes in which output line. It helps in controlling
and minimizing the data traffic.

9. SWITCH
A switch is network device that connects devices on a computer
network by using packet switching to receive, and forward data to the
destination device. It is similar to Hub but better than it. A switch can
join multiple computers within one LAN, and a hub just connects
multiple Ethernet devices together as a single segment.
A switch on other hand, does not distribute signals without verifying
whether it really needs to propagate to given port or not. It verify on
base of its internal configuration settings. We can say that a Switch is
a Hub with some intelligence.

10. BRIDGE
A bridge is a type of computer network device that provides
interconnection with other networks that use the same
protocol. Bridge devices work at the data link layer of the Open System
Interconnect (OSI) model, connecting two different networks together and
providing communication between them.

11. BRIDGE
• A bridge functions very similar to a switch. It segments a given
network according to the requirements.
• Segmentation using bridge enables keeping unnecessary traffic
from entering different segments of network.
Bridge performs three basic functions:
• Examining and learning the address of the nodes.
• Frame filtering, reformatting and forwarding.
• Routing the frames.
Bridge are of two types:
1. Transparent Bridge
2. Source Routing Bridge

12. REPEATERS
Repeater is a simple hardware device that moves all data packets from
one LAN segment to another. During movement it regenerates, and
amplifies the electrical signals. A repeater takes incoming signals and
repeats it at a higher power so that network speed can be recovered. At
same time it makes signal noise free too.

13. ROUTER
• A router is a device that forwards data packets along networks. It
connects multiple networks and uses routing to forward packets.
• A router is connected to at least two networks, commonly two LANs
or WANs or a LAN and its ISP's network.
• A router is a intelligent connecting device that can send packets to
the correct LAN segment to deliver it to its destination.
• A router finds best route for delivery while data is transmitted

14. GATEWAYS
• A device which is used to bridge different network architectures is known
as “gateway”.
• It can handle messages, addresses and protocol for delivery of a packet to
its destination between two networks.
• Gateways are usually slower than the Bridges and Routers.
• The gateways are used to connect two networks that do not communicate
with the same network protocol.
• Gateways translate these protocols between both networks.

15. MODEM
• Modem stands for Modulator and Demodulator .
• A modem is used to send digital data over phone line.
• The sending modem modulates the data into analog signal compatible
to phone line.
• The receiving modem demodulates the signal back into digital data.
• Wireless modems convert digital data into wave signals.

16. 1. Internal and External Modems: Internal modems are in form
of circuit boards, fitted in expansion slots of motherboard.
External modems are enclosed in separate cases and not inside
system units. It is connected to computer and telephone line by
means of two separate cables.
2. Intelligent and Standard Modems: The standard modems
accept instructions entered from keyboard of a microcomputer
and respond to commands and transmits information
simultaneously. It is done with help of microprocessor chips.
3. Wireless and Short-Haul Modems: Short-Haul modems
transfer data by means of cables. Since they don’t need external
power source, they are also called modem eliminators. The
wireless modems don’t require any kind of cable to transmit the
data signals. It transmit data signals through air.
TYPES OF MODEM

17. MULTIPLEXER
• In electronics, a multiplexer (or mux) is a device that selects between
several analog or digital input signals and forwards it to a single output line.
• A multiplexer is a device that merges several lower speed transmission
channels into one high speed channel at one end of the link.
• Reverse of multiplexing is called demultiplexing
• Multiplexing is done at sender send and demultiplexing is done at receiver
end

18. FIREWALL TECHNOLOGY
Firewall is a system designed to prevent unauthorized access to or
from the private network.

19. • A firewall is a network security system that monitors and controls
incoming and outgoing network traffic based on predetermined
security rules.
• A firewall typically establishes a barrier between a trusted internal
network and untrusted external network, such as the Internet.
• Firewalls can be implemented on both hardware and software.
• Firewalls are commonly used to prevent unauthorized users from
accessing private networks connected to internet.
• All message entering and leaving through intranet pass through
the firewall.
• Firewall examines each message and blocks those that do not
meet the specified security criteria.
FIREWALL

20. FIREWALL TECHNIQUES
 Packet Filters: Looks at each packet entering or leaving the
network and accepts and rejects on user defined rules.
 Application gateway: Applies security mechanisms to
specific applications, such as FTP and Telnet servers.
 Circuit level gateway: Applies security mechanisms when a
TCP or UDP connection is established. Once connection is
made, packets can flow between the hosts without further
checking.
 Proxy server: Intercepts all messages entering and leaving
the network. The proxy server effectively hides the true
network addresses.

21. FIREWALL TYPES
 Host Based Firewalls: Host based firewalls are popularly known as
personal firewalls are devices or programs intended to protect a single
computer. The personal firewalls are generally software based.
E.g. Norton Personal Firewalls and Internet Connection Firewall
 Network Based Firewalls: It normally protects entire network of
computer behind firewall.
a) Software based firewalls: A firewall that runs on generic OS such
as Windows and Linux is known as software firewall.
b) Hardware based firewalls: Firewalls that run in proprietary
hardware and software environment are known as hardware based
firewalls.
 Enterprise Firewalls: Enterprise firewalls are designed for large
geographically distributed networks. They are capable of handling
1000s of users, have faster throughput, and have advanced features.
It have ability to manage multiple firewalls centrally.

22. FIREWALL
 ADVANTAGES OF HARDWARE FIREWALLS:
• Faster speed
• More security
 DISADVANTAGES OF HARDWARE FIREWALLS:
• More costly than software firewalls
• Difficult to install
 ADVANTAGES OF SOFTWARE FIREWALLS:
• Cheaper
• Ideal for personal use or home use
• Easy to configure
 DISADVANTAGES OF HARDWARE FIREWALLS:
• Takes up system resources
• Difficult to remove or un-install