Chp 4: Networks & the Effects of Using Them

4.1 Networks
Networks
Routers
A device that enables data to be sent between different types of networks. It can be connected through cables or wirelessly
to connect a LAN to the internet.
It can be used for:
● connecting networks and devices to the internet,
● storing computer addresses,
● routing data packets.
When a data packet is received, the router checks if the packet is intended for it or another network. The data packet is
routed to the local switch/hub if it's meant for its network. If not, the data packet is sent to the relevant router, which sends it
to the relevant device.
● They consult routing cables to know where to send the data.
Common Network Devices
1. Network Interface Cards (NIC): These are needed to allow a device to connect to a network. Turns binary data into
an electrical signal that allows network access. Usually integrated into the motherboard.
● Each NIC is given a unique hardwired media access control (MAC) address.
Media access control (MAC) address: a number that uniquely identifies a device when connected to a network.
● The first six hex digits identify the manufacturer’s code, and the next 6 identify the device’s serial number.
2. Hubs: they are hardware devices that can have several other devices connected to them. They are used
to connect devices together to form a local area network (LAN). It takes a data packet received by one of
its ports and sends it to all relevant or irrelevant devices that are connected to it.
● It is not very secure to broadcast data to all devices.
● Unnecessary network traffic.
3. Switches: intelligent hubs. Used to connect devices to form a LAN. Unlike hubs, the switches store the
MAC addresses of all devices on a lookup table. So, it only sends data to the relevant device.
In summary:
● Both are used to connect devices in LAN.
● Both use data packets.
● Hubs send data to every device on the network.
● Switches send data to a relevant device only.
● Switches have better security.
● Switches use lookup tables to determine the destination for a data packet.
● Switches use MAC addresses for relevant device locations.
 4. Bridges: Devices that connect one LAN to another LAN that use the same protocol. Unlike routers, they
can’t communicate with external networks, such as the Internet.
Comparison:
● Bridges connect LANs together; routers connect various types of networks together.
● Bridges scan MAC addresses while routers scan the IP addresses.
● Both send out data in the form of data packets.
● Bridges connect networks with the same protocol; routers can connect networks with different protocols.
● The router uses routing tables to direct data packets, but bridges don’t.
● Bridges have only two ports; routers have multiple ports.
Wi-Fi & Bluetooth
Both are used for wireless communication between devices. They both use electromagnetic radiation as the
carrier of data transmission.
Bluetooth uses:
● When transferring data between 2 or more devices that are very close together.
● When the speed of data transmission isn’t crucial.
● For low-bandwidth applications.
Wi-Fi uses:
● Full-scale networks.
● When the data transfer rate is crucial.
● For uses where a higher range and better security are required.
Differences and similarities:
● Bluetooth uses a transmission frequency of 2.4 GHz, whereas Wi-Fi uses a 2.4 – 5.0 GHz range.
● Wi-Fi has a much faster data transfer rate.
● Wi-Fi has a higher geographical range in which it is effective.
● Bluetooth only allows up to 7 devices to be connected simultaneously, whereas the number of devices
connected to a Wi-Fi network depends on the router/routers used.
● Bluetooth uses key-matching encryption. However, Wi-Fi uses WPA (Wi-Fi protected access) and
WEP (wireless equivalent privacy).
Common Network Environments
1. Internet:
● The Internet is a very large global network that consists of many other interconnected networks
● The World Wide Web is a vast collection of web pages that can be accessed using a web browser.
● The World Wide Web allows you to access information by using the internet
Characteristics:
● It is an open network, meaning everyone can access the same resources and information as everybody
else.
● People from all over the world can communicate with each other in real-time.
● Available to anyone who has a suitable device and access to any one of the interconnected networks.
Uses:
● Education and training
● Social Networking
● Online shopping
● Entertainment..
2. Intranet:
● Usually private and are used to send information securely and safely.
● Access to an organization’s Intranet is restricted and only accessible to authorized users such as
employees.
● Intranets have many advantages over the internet, such as:
○ better bandwidth than the internet,
○ data is kept within the organization,
○ less chance of hacking and attacks,
○ administrators can manage access to external sites and links.
Characteristics:
● A private network that is accessible to employees within a company or organization.
● Usually behind a firewall to ensure security.
● Allows for document sharing and the use of collaboration tools between users.
● It can be customized to meet the specific requirements of the business.
● Users will require a username and password to access the Intranet.
3. Extranet:
● Private Intranet that also allows access by selected parties that reside outside of the organization.
These parties, for example, maybe customers, key stakeholders or clients.
● Users will have an authorization level once they have successfully logged in, which will determine which
resources they may access.
● Similarities between the Internet, Intranet and extranet are as follows:
○ They are all web-based technologies
○ They allow users to access information remotely
○ They all use client-server architecture
○ They all use security measures such as authentication and encryption
○ They all promote and facilitate information and resource sharing
● Differences between the internet, intranet and extranet are as follows:
○ The internet is a global network, whereas an intranet/extranet is a private network contained
within an organization
○ The use of the internet covers a wide range of purposes, whereas an intranet/extranet is
designed for specific users and purposes.
○ Much information is publicly available, whereas an intranet/extranet is not.
○ The Internet is not owned solely by one person or organization, whereas the organization usually
owns intranets/extranets.
Network Types
1. Local Area Network (LAN): networks usually contained within a single building or small geographical
location. It is made up of hubs and/or switches, which will connect several devices together. One hub or
switch commonly connects to a router, allowing LAN connectivity to other outside networks such as the
Internet.
Advantages:
● Allows centralized management of updates, backups and software installations.
● Can secure its devices with the use of firewalls, antivirus software and other security features to
prevent unauthorized access.
● A LAN allows users on the network to share resources such as printers and other peripherals.
Disadvantages:
● The network may not function correctly in case of hardware failure.
● They are more prone to attacks than standalone computers.
● Data and peripheral accessing can be slow, based on network traffic.
● LAN networks require maintenance to ensure the software is up-to-date.
 2. Wireless Local Area Network (WLAN): Local Area Networks allow devices to connect wirelessly rather
than using physical cables. Wireless Access Points (WAPs) are connected to an existing wired network,
which provides wireless connectivity. Support a vast range of devices, such as smartphones and laptops,
are very popular in public areas such as shopping malls.
Advantages:
● Allows users to connect anywhere in the range of a Wireless Access Point (WAP).
● They can be used in various indoor and outdoor environments, making them highly flexible.
● As the requirements change, additional WAPs can be added relatively easily.
● Printer access can be given to wireless devices.
Disadvantages:
● The strength of their signals can be affected by obstacles such as walls.
● Speeds can be affected by high-traffic areas.
● It can sustain interference from other devices which can affect performance and connectivity.
● Can be vulnerable to security threats due to signal interception.
 3. Wide Area Networks (WAN): is formed by several LANs connected through a router. It is
expensive. However, it comes with a more enhanced security. Additional hardware is needed
for a WAN: Routers, modems, and proxy servers.
Advantages:

● Provide the ability to connect geographically dispersed locations, such as offices in different
cities or countries.
● Offer the flexibility to scale up or down based on the organisation's needs.
● Administrators can monitor and manage the network infrastructure from a single location.
Disadvantages:

● Setting up and maintaining a WAN can be expensive, especially compared to LANs.