CT.pdf - New & Emerging Technologies & Communications

## 13.1 Types of new and emerging technologies **Much reduced**. This makes research available more quickly to other scientists for review, comment and use. **Holographic imaging** is used to visualise objects in three dimensions. When used with virtual reality, it can enable scientists to move ar...

## 13.1 Types of new and emerging technologies **Much reduced**. This makes research available more quickly to other scientists for review, comment and use. **Holographic imaging** is used to visualise objects in three dimensions. When used with virtual reality, it can enable scientists to move around and inside objects in ways that are not physically possible. Chemical molecules, for example new drugs, can be examined and researched. Parts of the molecules can be moved to find out the effect of doing so. Biological structures can be digitised and the images studied. **Scientists use holographic and fourth-generation storage** because their research can generate huge amounts of data and this must be kept safe. Current holographic and fourth-generation storage is expensive, but it may be the only choice for saving and archiving massive quantities of data for future study. The reduced data-access times of holographic and fourth-generation storage are useful for accessing and analysing the large amounts of data. **3D printing of scanned and digitised objects**, for example fossils, enables the study of objects that are too fragile to touch. The printed models can be handled and moved without fear of damage to the originals. Multiple copies can easily be made available to different scientists or the 3D printer files sent across the world for printing. **Vision enhancement**, with smartglasses, headsets or display screens, can allow scientists to study very small or very distant objects, or objects that reflect light outside the range of human vision. Robotic devices with cameras can enhance the images in various ways to study the environment in which the robotic device is operating. ### Activity 13m Explain why scientific research often requires the use of high-performance computer systems. ## 13.1.17 The impact of new and emerging technologies on the environment ### E-Waste and recycling **E-waste**, or electronic waste, is discarded electronic devices. The discarded devices can be recycled, reused or dismantled. **Recycling** of complete devices often means they are reused by others without being dismantled for parts. **Dismantling and recovering parts and components** to be used in new devices is true recycling. **Gold, silver, nickel and aluminium**, used in circuitry and connections, are not usually directly hazardous to health, but high levels of them are to be avoided. **Cadmium, lithium, manganese, copper and lead**, and many others, are used in electronic components, circuit boards and solder joints in varying quantities, and all can cause environmental damage. **Components and parts that cannot be reused or recycled**, either because it is not economic to do so or because they are no longer suitable, have to be disposed of. **Rare, dangerous and other metals are often left in the discarded waste**. Eventually these metals will leach into the environment and water supplies and may cause damage to crops, animals and human health. **Polymers and plastics used to make cases, supports, covers, wiring and switches are difficult to reuse and recycle**. These remain in the environment for many years without degrading. When plastics are burnt or do eventually degrade, they may release noxious compounds or elements into the environment. **Chlorine is used in the manufacture of, and is found in, some plastics and its release is harmful to life.** **The disposal of e-waste can be by mechanically stripping the material from the device, or by burning the materials and attempting to recover some materials from the ashes**. **Burning destroys the components and releases noxious fumes into the atmosphere unless carried out safely and carefully**. **Industrial containment and safe plants are required to prevent contamination of the air, water supplies and surrounding lands.** **Vast quantities of components and parts that cannot be recycled or recovered are shipped from one country to another for disposal and may end up buried in landfill**. Sometimes, this may be because other countries have better disposal facilities, lower costs or fewer regulations regarding waste disposal. However, the shipping of e-waste around the world can add to the environmental damage. People living near recycling facilities, or near to landfill areas where e-waste is dumped, may feel the effects of hazardous materials, and may become ill or suffer other health problems. **Exposure to hazardous e-waste has been known to affect unborn children.** ### Power consumption As previously discussed, all new and emerging technology requires power to work. The increase in computing power demanded by new technologies used in manufacturing and by businesses, organisations and individuals increases the demand for electrical power. The incorporation of microprocessors, internet capability and communications systems into new areas, for instance home appliances, telecommunications with mobile devices, health care, scientific research and many other areas, has led to further increases in demand for electrical power. ### Manufacturing processes The use of new and emerging technology in manufacturing has reduced costs, increased productivity and increased the consistency and quality of goods. However, there has been an impact on the environment. New technologies in manufacturing often require more electrical power as they run continuously through the day and night. They use raw materials that are already scarce, for example rare metals, and that require extensive mining to extract. New technologies in manufacturing also create waste materials that are difficult to dispose of without considerable cost, and create goods that do not degrade so their components remain in the environment for many years. **Plastics are a major component of many new technologies**, for example robotic devices that are used in many manufacturing processes. **Beneficial impacts** are that manufacturing waste has been reduced, goods last longer so do not need to be replaced so often, working environments are safer for workers, and workers do not need to work very long hours to produce as many goods so they have a healthier lifestyle. For example, using 3D printers in a manufacturing process can reduce overall production times because there is no need for complex milling or drilling of complex shapes, but only the removal of the support materials and final clean-up. This produces longer-lasting goods in a safer workplace. **Waste is reduced and there is less power consumption.** **Robotics also reduces waste** as there are fewer errors in production and goods are more consistently assembled. **Using robotics with AI can help to detect production problems**, for example by more quickly recognising and comparing the production items with pre-set values of perfect objects, so fewer imperfect goods are made and then rejected. ### Practice questions 1. Describe how analysing social-media posts can be used to target users with advertisements. 2. Describe how shoppers could make use of augmented reality (AR) when buying clothes in a store. 3. Explain why surgery from remote locations using robotic devices is more risky than surgery carried out by a surgeon in person. 4. Discuss the impact of wearable computing devices in health care. 5. Discuss the benefits and drawbacks of using robotic devices to manufacture automobiles. 6. Discuss the benefits and drawbacks of the use of computer-aided translation by a company that produces TV sets for the global market. 7. Describe the impact of holographic imaging on commerce. 8. Describe how the disposal of computing devices that are old and no longer usable can pose a danger to the environment. ## 14 Communications Technology ## 14 Communications technology In this chapter you will learn: * The types of computer networks * The role and operations of the components found in computer networks * About network servers and their role in networking * About cloud computing * How data is transmitted and routed across networks * The protocols that enable data to be exchanged between computing devices, across networks and over the internet * About wired, wireless and mobile (cellular) networks * About network security protecting data * How recovery from disasters can be managed. Before starting this chapter, you should: * Be familiar with the terms: component, peripheral, internet and internet-based services, hardware, software, types of computing device (for example desktop and laptop computers), tablets and smartphones, networks and associated types and components, malware and backup. ## 14.1 Networks ### 14.1.1 Types of network A computer network connects computing devices, called 'network nodes', together to enable the exchange of data and access to shared peripherals, for example printers or storage devices, the world wide web, the use of internet-based services such as email, messaging, cloud storage systems and video streaming, and many more. ### Local area network A local area network (LAN) is an internal network that is restricted to a specific area or organisation, such as a school or college campus, a home or a business, and can only be accessed by users belonging to the organisation. LANs communicate at layers 1 and 2 in the Open Systems Interconnection (OSI) model, which is a conceptual model that describes networking in seven layers. LANs use, for example, ethernet technology, which is designed for communication over relatively short distances compared to WANS. LANs do not normally use public telecommunications systems but may be interconnected into a metropolitan area network (MAN) to create a larger LAN that covers, for example, a city for use by city officials in different buildings. #### Characteristics of LANS LANs can have various network topologies connecting nodes together using physical cables, wireless connections and optical connections, and are characterised by covering a relatively small geographical area of usually only a few kilometres. This can be extended, for example by using VPNs, between buildings or campuses to cover much larger areas. Data transfer speeds over LANs can be very high, often in excess of hundreds of gigabits per second. The maximum possible data transfer rates are rarely achieved because some capacity is taken up by the processing of the protocol headers, error corrections, packet collisions and media imperfections. Installation of LANs is relatively easy and has a lower cost than WANs because the area to be covered is smaller, and maintenance is easier because the connection media and devices are similar and compatible. The scalability of LANs is good because they can be extended quickly and easily by adding new devices and transmission media. #### Uses of LANS LANs are used by schools, colleges and other educational organisations to connect together computing devices, such as desktop computers, laptops, tablets and smartphones to enable the exchange of data such as images and videos, files and applications and other digital resources. Peripherals such as printers, scanners and networked storage systems can be shared by network users, which reduces the number, and the running costs, of peripherals. Networked resources, courses and teaching materials can be shared and made available on the network. Teachers can be sent work by students to assess and can send back the results. Businesses, organisations and governments use LANs to connect computing devices to share and exchange data, information and resources. Company files, house-style documents and templates can be centrally stored and accessed by employees so that all company documentation has the same style, layout and appearance. #### Protocols used by LANs Using protocols specified by the Institute of Electrical and Electronics Engineers (IEEE) ensures that networked devices can connect to others anywhere in the world. Ethernet is a networking technology that divides data into frames (packets) that carry the source and destination addresses and basic error-checking data, for transmission over wired connections. Wi-Fi technology does the same for wireless connections. Ethernet and Wi-Fi are the standard technologies for use in LANs and WANs. They work at the lower layers of the TCP/IP and OSI models, and their frames carry the TCP/IP packet information. The TCP/IP model is a conceptual model that describes networking in four layers. The network protocols used on LANs are discussed later in this chapter in Section 14.6 'Network protocols'. #### Advantages and disadvantages of LANs **Table 14.1 Advantages of LANs** LANs reduce the number of peripherals required so there is a reduction in the initial costs of purchase and the running costs of peripherals as there are fewer to maintain. Users may have access to a wider range of peripherals and can choose which printer (inkjet, laser, larger paper size) to use for a particular job. Data, files and documents can easily be shared between users, and company documentation and templates, for example house styles for documentation, can be stored centrally for access by employees. Centrally stored data can be kept safer and more secure by automatic scheduling of backups and archives, and authentication techniques can control access to it. Central storage can provide an application server that is easier to maintain and update than having multiple copies of software applications installed on individual computers. LANs allow communication, for example by email, so that messages, documentation and notifications can be sent to many users, saving the time and cost of duplicating individual messages. Employers can control and monitor what employees are sending and receiving over LANs. Users on a LAN can share a single access point to the internet, where the data leaving and entering the LAN can be controlled and monitored. Shared internet connections from LANs reduce the number of Internet Protocol (IP) addresses that are needed, so one IP address is shown to the internet and hides the IP addresses of the LAN devices from public view. This increases privacy and security. A LAN reduces the time and costs of the maintenance of computers, other devices and software used on the LAN. New software, software updates and other administrative tasks can be centrally organised and distributed. LANs in a home allow members of a household to share peripherals, share a single internet access and set up a smart home controlling and accessing household goods and appliances. The use of Wi-Fi to connect tablets and smartphones, and other mobile devices, allows household members to move around the house with their devices and to use the devices from any location in the house. **Table 14.2 Disadvantages of LANs** The smaller geographic areas covered by LANs can be a disadvantage compared to greater coverage by WANs and mobile networks. Using WANs, mobile technologies and VPNs to extend a LAN adds to the complexity, cost and difficulty of use. A network administrator, or technician support, is usually needed to diagnose and solve network problems and to service and maintain a LAN. This can add to the costs of running an organisation. It can also create privacy concerns for users as a LAN administrator usually has access to all stored data and information on the LAN. Users should encrypt their data and files, but this adds to the complexity of use and to the time taken to process the data. If users store their data on removable storage to protect it, then this undermines the purpose of having a LAN. Also, they may introduce malware via the removable devices. Internet browsing history and personal emails are also available to a LAN administrator when used on a company LAN. Malware can easily spread from device to device over a LAN. Computer viruses, ransomware, Trojans, spyware, adware and other malware can be passed from one device to another over a LAN. Data and files can be damaged, lost or stolen more easily if used and stored on a LAN. ### Wide area network A wide area network (WAN) is a computer network that covers a much larger area than a LAN. It makes use of telecommunications systems to connect nodes from locations distant from each other, such as between cities, regions and countries. Leased, private data lines between geographically separated offices create circuits on public telecommunications systems to become a WAN for global organisations. WANs operate at layers 1, 2 and 3 in the OSI model, which specify the structuring, management and control of network traffic and allow the exchange of data over long distances. WANs use technologies such as Multiprotocol Label Switching (MPLS), Asynchronous Transfer Mode (ATM), frame relay and X.25 for data exchange over public communications systems. #### Characteristics of WANS A WAN is distinguished from a LAN by its use of communication media such as public or leased telecommunications systems and network infrastructure that are not owned or run by a single organisation. Typically, a WAN will cover a greater geographical area than a LAN because the connected LANS are far enough apart from each other to require the use of telecommunication lines. The internet may be regarded as a wide area network that uses public telecommunications systems. WANs make use of different transmission media including the various types of copper cabling, wireless, fibre-optic, microwave and satellite communications systems, often for very long-distance connections. A WAN uses switching and routing technologies to direct the data from the sending device to the receiver. Data travels across the WAN in packets, and is stored on intermediate devices and then forwarded to the next device (called the 'store-and-forward' method of transmission). This is one of the reasons that sending data across WANs may not be as secure as on LANs. **Encrypting the data is a solution to this problem.** **More data transmission errors occur on WANs compared to LANs because the longer distances involve many interconnections and differing technologies**. These add to the background noise that interferes with the data transmission and can cause delays in the propagation of data across the WAN. **Video and audio streaming may be seriously affected by propagation delays.** **WANs have lower data transfer speeds than LANs** because the different transmission media used for the connections require conversions between different protocols; the requirement for routing protocols, the different transmission media and the number of intermediate devices reduces data transfer speeds. WANs can transfer data at about 150 to 200 megabits per second, whereas LANs can reach rates of hundreds of gigabits per second. #### Uses of WANS Wide area networks are used to connect computing devices into a network covering a large geographical area, for example several countries. Businesses, organisations, educational establishments and governments use WANs to exchange data between computers in their remote offices around the world. The internet can be considered to be a WAN, and is used by people all around the world to exchange data, share files, use email and other social-networking platforms, and search for information. #### Protocols used by WANs Wide area networks use High-level Data Link Control (HDLC), Point-to-Point Protocol (PPP) and frame relay to create the frames (packets) that are transmitted across a WAN, in the same way as Ethernet or Wi-Fi protocols create the frames for LANs. HDLC requires little configuration and is used by routers to connect LANS into a WAN using leased telecommunications lines. A router on a LAN uses HDLC to repackage packets from the LAN and send them along the line to a router on another LAN. The packets are converted back for use on the other LAN. HDLC provides error correction for data sent over WANS. PPP is based on HDLC and is also used to connect LANs via leased lines. It is customised for use on dial-up connections into WANs or into the internet. It authenticates and checks the quality of a dial-up connection. Frame relay is used in packet-switching networks such as an Integrated Services Digital Network (ISDN) and in permanent virtual circuits (PVN) and enables data to be transferred across public telecommunications systems. Frame relay can be used to set up a PVN across public telecommunications systems so that a user appears to have a private connection to the WAN or the internet. It can also be used to connect a home LAN, via a router, to the internet via broadband. Frame relay works at the layers 2 and 3 - the Data Link and Network layers of the OSI model and puts data into variable-sized frames (packets). Frame relay does not provide error correction, so it can be unreliable. Devices using frame relay are expected to provide any required error-correction procedures. It can be set up to allow a quality of service (QoS) configuration to prioritise, for example, video streams. Multiprotocol Label Switching (MPLS) is a routing system used on WANs to carry packets of data using other protocols, such as frame relay. It uses short labels instead of long network addresses to identify nodes and passes the packets quickly between nodes. Its use can increase data transfer speeds. #### Advantages and disadvantages of WANs **Table 14.3 Advantages and disadvantages of WANs** **Advantages** * For a company with locations in different areas, connecting LANs into a WAN means that resources can be centralised at head office or in a data centre, making the maintenance, updates, backup and archiving of resources simpler. Users can access all of the company resources regardless of their physical location. * The use of private, leased lines or virtual private networks means that company data does not pass openly over the public telecommunications networks so is kept private and secure. * WANs can also be used to carry voice calls, using VoIP, so the costs of telephone calls between office locations can be reduced. * Conference calls, and video and web-conferencing, can be made using WANs and the discussions can be kept entirely within the company. **Disadvantages** * WANs have high costs of initial set-up because locations are far apart. Technicians setting up WANs may have to travel long distances several times to ensure the correct operation of the WAN. * The gathering of data and resources into centralised locations, such as data centres, may increase the security of the data at the data centre, but can reduce the security resources and personnel available at remote locations, due to costs. This may make the data at these locations less secure and more vulnerable. * WANs may have increased maintenance difficulties and costs. A centralised data centre must run continuously with little or no downtime. Administrators must ensure that the data and resources are available around the clock because company locations using the data centres on a WAN may be in different time zones and work at different times. * The maintenance and management of the links and of leased telecommunication lines increase the costs to companies. This cost may be higher when compared to the use of VPNs over the internet where the costs of the telecoms lines are borne by the telecoms operator and, in the case of problems, traffic is automatically redirected. ### Activity 14a 1. One of the main differences between a LAN and a WAN is the geographical area that they each cover. Describe three other differences. 2. List the main protocols used on LANs. 3. List the main protocols used on WANs. ### Client-server network A client-server network system consists of devices (the clients) that connect to servers providing the services requested by the clients. Clients can be personal computers, laptops or smartphones that request data, files, applications and websites from servers. A client makes a request to the server, which responds to the client by sending the results of the request back to the client. The client and the server must use the same protocol, operating at the Application layer (layer 7) of the OSI model. The data transferred between clients and servers may be encrypted for security. Servers have a scheduling system to prioritise requests and to limit the number of requests from clients. However, very large numbers of requests may result in a denial of service (DoS). #### Characteristics of client-server networks Client-server networks use the request-response model. The client requests a service from the server, which gives a response. Clients do not share any of their resources with the servers and rely on the servers to provide services and content as requested. The server does not initiate client-server sessions but waits for a client to request its services. Servers can support many clients at once. Low-powered clients use, over a network, the higher processing power and greater primary and secondary storage of servers. The client has only to be able to act as an interface for the user and to be able to initiate requests to the server. #### Uses of client-server networks Web servers store web pages and only send them to web browsers (the clients) when the browsers request them. A series of requests and responses may be required to complete the transfer of all the components of a web page. Similarly, an email client will request a message from an email server when the user logs into the email account, for example from a smartphone. Printing from a client to a networked printer, the upload or download of files between clients and file servers, and the posting of photos to social-media websites are further examples of client-server networking. #### Protocols used by client-server networks Client-server networks use the communication protocols of the network (LAN or WAN) upon which they run. Moving files between a laptop and a file server using the File Transfer Protocol (FTP) is an example of a client-server network. The exchanges between client and server use protocols that work in the Application layer of the OSI model, making use of application programming interfaces (API) provided by software creators for their applications. #### Advantages and disadvantages of client-server networks **Table 14.4 Advantages and disadvantages of client-server networks** **Advantages** * Client-server networks have central administration where access rights and allocation of resources are managed by the servers, allowing much greater control over who can or cannot access and use the resources compared to peer-to-peer networks. * Files are stored in one central area and can be found and administered more easily by all users than if they are stored on local hard disks. * A backup and recovery schedule of the files on the server is administered centrally and not by individual users, who do not need to take responsibility for this. **Disadvantages** * The files or services cannot be accessed by clients or users if the server or network fails. * Managing the servers and access rights and permissions can be more complex and usually needs skilled IT technicians, adding to the costs of maintaining the client-server network. * There is a great deal of network traffic when client-server networks are used and this can result in congestion on the network and a perceived reduction in performance by users. ### Peer-to-peer networks Peer-to-peer networking connects nodes (physical devices) together on an equal basis. Nodes may share some of their resources, such as processing power, data storage systems or bandwidth with other peers, but there is no central server to control or co-ordinate the sharing. Because resources are shared between nodes, peer-to-peer networking can be seen as a form of distributed computing. #### Characteristics of peer-to-peer networks Most peer-to-peer networks are unstructured and connections are made as and when, and where, they are required. It is easy to quickly create a local peer-to-peer network by this ad hoc approach. Peer-to-peer networks are very robust and resistant to changes in the network, so nodes can join and leave the network without causing significant errors. #### Uses of peer-to-peer networks Peer-to-peer networks are used to distribute and share digital content, such as digital books, music, computer games, videos and images, to users. Users can search, locate and download digital media from several nodes at once. As the number of nodes storing and sharing the content grows, the capacity of the network increases. File sharing between nodes is a popular use of peer-to-peer networking. Files can be searched for and downloaded from many nodes at once, which increases the speed of download to a node. Once downloaded, the node can make the file available to other nodes. BitTorrent is an example of file sharing using peer-to-peer methods. Large files can be quickly downloaded using BitTorrent. Software companies can use their own proprietary systems to distribute operating systems or applications. Computer files shared by peer-to-peer networking can be altered by any node and can carry malware. Complex systems have been developed for checking the integrity of shared files. #### Protocols used in peer-to-peer networks Peer-to-peer networking protocols all provide the means for connections to be made between nodes without a central server. Digital currency transactions, for example Bitcoin and Litecoin, use peer-to-peer networking. Bitcoin uses a protocol that encrypts transactions and allows nodes to join and leave the network at any time. BitTorrent's protocol is used by several client applications to prepare, transmit and request files over a network. Originally, a small text file would be prepared. The text file, called a 'torrent', contained information, for example file names and sizes, about the files to be shared and the IP addresses of the 'trackers' that stored data about the location of peers on the network that had the complete requested file. Computers that held the complete requested file were called 'seeds'. The trackers were computers that stored lists of seeds and together formed 'swarms'. To download a file, a BitTorrent client first obtained the torrent file and used it to locate trackers and seeds. Multiple requests for torrents from many peers could overwhelm a peer-to-peer network and lead to 'query flooding' of the network. BitTorrent now uses a distributed hash table instead of seeds. BitTorrent downloads require less bandwidth, and are often completed in far less time, than downloads using FTP or HΤΤΡ. #### Advantages and disadvantages of peer-to-peer networks **Table 14.5 Advantages and disadvantages of peer-to-peer networks** **Advantages** * Using a peer-to-peer network removes the costs and administrative time of having a central server. Devices can be quickly and easily added to or removed from peer-to-peer networks, so a peer-to-peer network can be created or shut down quickly with little configuration needed. * Removal or addition of nodes does not affect the operation of the other nodes. * Exchanging files between mobile devices is quick and convenient for users over peer-to-peer networks, such as Apple AirDrop for iPads and iPhones®. * The user's privacy is increased as there is no central record of who is using the network and what it is being used for. **Disadvantages** * Peer-to-peer networks can be insecure as each device has to manage its own security. * There is no central storage of data so archiving and backups of data and files have to be carried out by individual nodes. * No central server means that there is no central record of the users or of what data and files are being exchanged. Illegal activities are difficult to discover and prevent when users use peer-to-peer networks. * Multiple requests from and to nodes, or searching for resources, create a high amount of network traffic. Multiple requests also increase the processing required by the nodes, with the result that requests often fail and nodes do not find what they are looking for. ### Activity 14b Explain why the lack of central control in peer-to-peer networking has drawbacks. ### Virtual private networks Virtual private networks (VPPNs) allow nodes to connect to private LANs using public telecommunications systems, so users can use them to exchange data as if they were connected directly to the private LAN. It appears to the user that the private LAN is being extended across a public telecoms network to wherever they may be located. Because VPNs can connect across the internet, an employee can be anywhere in the world and still connect to the employer's private LAN. VPNs can be used to connect several LANS into a WAN. VPNs are available to individuals and business users. Network traffic is directed to a VPN server where the user's IP address, data and other details are changed so they appear to be coming from the VPN server. VPNs use tunneling protocols that operate at layers 1 and 2 of the OSI model. A tunneling protocol using authentication and encryption provides a secure connection that allows the exchange of sensitive and confidential information between the users and their companies or organisations. #### Characteristics of VPNs A virtual private network creates a point-to-point connection between two nodes over a public telecommunications system. A VPN can connect two nodes, for example two laptops on different networks, to create one logical network. Connecting a single node to a network over a VPN makes it a logical part of the network regardless of its distance from the network. Most basic VPNs do not support all LAN protocols, but commercial installations of VPNs can extend the LAN without any reduction in its capabilities. VPNs require users to authenticate so that their data is transferred securely. Usually, a username and password are used, but businesses and organisations may require their employees to use biometric methods, a dongle or two-factor authentication. Digital certificates can be used where VPNs connect two or more networks. The certificates can be stored to allow the networks to connect automatically. **Encryption can be used to ensure that any data captured or intercepted is unintelligible to unauthorised viewers**. **Integrity checks on the data detect attempts to interfere with the data.** #### Businesses, organisations and governments use VPNs to create a secure connection. Extending a LAN over public telecommunications networks between different buildings or areas allows employees to connect into their LANs from remote locations. Employees working at home can securely access the company resources as if they were physically present in the office. **Voice over Internet Protocol (VoIP) calls can be made more secure by using a VPN.** Individuals can use a VPN to create a secure connection when connecting mobile devices, such as laptops or smartphones, to public unencrypted Wi-Fi to keep user data and information secure. **Using a VPN when shopping online keeps shipping and credit card details encrypted and secure.** VPNs can also be used to avoid regional restrictions (geo-restrictions) when accessing media and information on the internet. A VPN connection can provide an internet address that reflects where the VPN connects into a LAN, instead of where the user is physically located. This is useful when connecting into a corporate LAN as the user is seen by the network services as being local so there are no regional restrictions. However, this feature of VPNs can be used to avoid restrictions on the use of copyright materials. Most video-streaming services have mechanisms in place to recognise when a user is connecting via a VPN and to prevent the illegal use of the streaming service. **Accessing social media from countries where social-networking platforms are censored or banned is made possible by the use of VPN connections**. Using VPNs can attempt to get around restrictions, so in some countries the use of VPNs is banned. #### Protocols used by VPNs The protocols are the Layer 2 Tunneling Protocol, Internet Protocol Security (IPsec) and Transport Layer Security (SSL/TLS). Layer 2 Tunneling Protocol creates the data packets, providing headers and packet information, for transmission over a VPN. Layer 2 Tunneling Protocol itself does not encrypt data but creates the connection - the tunnel - and leaves the encryption to Il'sec. IPsec encrypts an IP packet and places it inside an IPsec packet at one end of a VPN connection, and decrypts it back to the original IP packet at the other end. **Transport Layer Security (TLS) has replaced the Secure Sockets Layer protocol (SSL), and provides the authentication and encryption for data transmission over VPNs**. **Symmetric cryptography is used, with the keys being exchanged by TLS using a 'handshake' at the start of a connection session**. The connection is secure from unauthorised users because the keys cannot be discovered and any interference with the transmitted data can be detected. **IPsec may be unreliable because firewalls may block IPsec data packets due to an inability to read the encrypted IP addresses**. **TLS connections are not affected in this way so are reliable.** **Point-to-Point Tunneling Protocols (PPTP) can also be used to create a tunnel and encapsulate the data packet**. **An additional protocol, for example Secure Shell (SSH), handles the encryption**. SSH creates the tunnel and carries out the encryption of the tunnel but not of the data. #### Advantages and disadvantages of VPNs **Table 14.6 Advantages and disadvantages of VPNs** **Advantages** * The main advantages of VPNs compared to other means of communication over public telecommunications systems are encryption and privacy. The encryption of data transmitted over a VPN ensures that the data is kept secure. * VPNs can help keep the user's internet use, search history and web browsing private. Some internet service providers analyse the type of data, for example email, web use or video streaming, and adjust the available download speeds or bandwidth. This adjustment may restrict the bandwidth available to a user; using a VPN makes this data analysis almost impossible. * Using a VPN to connect geographically distant company LANs over public telecommunications systems is cheaper than renting leased lines as it uses the internet with all its connections already in place. It allows the centralising of resources into data centres so maintenance costs are reduced and security is enhanced. **Disadvantages** * VPNs can have an adverse impact on the performance of a network. The network traffic of a VPN is directed via the servers of the VPN provider and these add a performance overhead to the traffic. VPNs take time to process and transmit data and requests for websites, so the overall network performance is reduced. * VPNs can be difficult and complex to set up and maintain. Free VPN services offer little if any technical support and often change their settings or shut down completely to avoid legal issues. * There may be compatibility problems when using VPNs. While most operating systems and devices are compatible with most VPNs, companies have to ensure that their employees and workers are using the same type of device to connect to the corporate LAN or WAN. * The privacy and anonymity of users is not completely secure. VPN providers may monitor the activity of their users and sell the IP addresses and search data. * The use of a VPN may be illegal in some countries and users may be subject to criminal penalties. ### Activity 14c Explain why company employees working from home use VPNs to connect to the company network over the internet. ### Mobile networks **Mobile**, or **cellular (cell)**, networks are wireless networks. Mobile networks work from base stations, located on poles, tall buildings or towers, which cover a small geographic area called a 'cell'. Base stations provide the mobile network coverage using radio signals that can be received and used by mobile devices such as cell phones. Cells in mobile networks are often drawn as hexagonal in shape because a hexagon is the best