In this section, you’ll discover some of the fundamental concepts of computer networking through a series of video tutorials. You can work through them at your own pace. Try not to watch them all in one go, as it’s a lot to take in – so pace yourself.
Video 1: Network Computing [21m]
Introduction to computer networking. In this video, you’ll learn about some of the fundamental concepts involved with network computing and introduce some of the key components of a computer network
Video 2: Network Communications [23m 52s]
In this video, you’ll learn about the fundamental concepts involved with network communication and discuss the underpinnings of the TCP/IP suite.
Video 3: Internet Primer [13m 34s]
In this video on the basics of the internet, you’ll learn about some of the fundamental concepts involved with the Internet and discuss how and why it works.
Video 4: Networking Security [9m 9s]
This video covers the key concepts of network security. You’ll learn about several key offerings designed to help you secure networks.
Video 5: Modern Communications [25m 21s]
This video covers the new ways in which we can communicate over computer networks, including wide-area mobile connectivity, VoIP, IP telephony, the Internet of Things (IoT) and 5G.
Video 6: Virtualisation and Cloud Technologies [17m 33s]
This video covers the key aspect of virtualisation and cloud technologies. You’ll learn about what we mean by these two terms, and what they mean for you in terms of security considerations.
Video 7: Network Troubleshooting [4m 32s]
Introduction to network troubleshooting tools - using ping, route, traceroute, tracepath, and netcat to troubleshoot Linux network problems.
When you’re ready, click ‘next’ to continue.
Welcome to this video on Modern Communications.
In it you’ll learn about some of the new ways in which we can communicate over computer networks. Specifically, you will learn about Wide area mobile connectivity, VoIP, IP telephony, WLAN, 802.11, the Internet of Things (IoT), 5G and WhatsApp and FaceTime.
One of the biggest changes to the way we communicate has happened through mobile connectivity – put simply, the rise of the mobile phone.
Early cellular networks were able to carry voice data to and from mobile phones, at fairly sedate but sufficient speeds to enable a conversation.
Over time the cellular infrastructure improved, providing greater data transfer rates. At the same time, our appetite for being connected whilst on the move increased, usually filling up the available capacity of the network.
Mobile devices are now able to access the Internet at similar, if not better speeds (in the case of 5G) than our laptops connected to our home broadband.
In a previous video you learnt about the idea that inputs into computers are digitised so that they can handle the input. A similar thing happens to our speech when we make a phone call on a mobile phone, so it is natural to extend the notion to making a phone call using the Internet.
The Voice Over Internet Protocol, or VoIP, is what allows this to happen.
Consumers now think of telecommunications in terms of both products and services.
For example, a customer-owned and customer-installed Wi-Fi local area network may be the first access link supporting a VoIP service, and a consumer may purchase a VoIP software package and install it on their personally owned and operated computer that connects to the Internet via an Internet service provider.
VoIP is sometimes described as IP Telephony, but it would be more correct to say that VoIP is an element of IP Telephony.
IP Telephony is a whole suite of capabilities, centered on the transmission of voice or audio data over an IP network, as well as the transmission of other media such as images and video.
An example of IP Telephony is Web-based conferencing, enabling geographically distant participants to take part in a meeting in exactly the same way as if they were in the same room, down to sharing whiteboards or documents is one such capability.
The important thing to remember here is that these interactions, depending on the network links involved, take place in real time and at a natural conversational pace.
The diagram on screen offers a simple explanation of how VoIP functions.
The main piece of equipment is the Media Gateway – this converts information from one state to another. Whether that is digitising our voice, or recreating our voice from its digital form.
It acts as the bridge between different types of network, such as a Public Switched Telephone Network (PSTN), or Global System for Mobile Communications (GSM), to the IP network.
Once the information is placed on the IP network, it is handled in exactly the same way as any other data – it is broken up into packets and sent off to its destination.
Let’s take a look at some of the other components involved in VoIP.
The equipment which consumers engage with most often is obviously the handset – that will be what we are speaking into and listening to. The handset needs to be equipped with the ability to convert our voice into IP, or be connected to a device that has that capability.
As with everything else on the Internet, there are signaling protocols designed for handling our VoIP data.
Session control protocol (SCP) is a method of creating multiple light-duty connections from a single TCP (Transmission Control Protocol) connection.
Several similar lightweight connections can be active simultaneously.
SCP is a session layer protocol in the Open Systems Interconnection (OSI) model.
H323 is a standard approved by the International Telecommunication Union (ITU) in 1996. It's designed to promote compatibility in videoconference transmissions over IP networks.
H323 was originally promoted as a way to provide consistency in audio, video and data packet transmissions in the event that a LAN did not provide guaranteed quality of service (QoS).
In the session layer (layer five in the seven-layer model), session layer protocols provide services for coordinating communication between local and remote applications, as well as establishing, managing and terminating connections.
The Gateway Control Protocol (Megaco, H.248) is an implementation of the media gateway control protocol architecture for providing telecommunication services across a converged Internetwork.
This network consists of the traditional public switched telephone network (PSTN) and modern packet networks, such as the Internet.
The Media Gateway Control Protocol (MGCP) is a signaling and call control communications protocol used in VoIP telecommunication systems. It implements the media gateway control protocol architecture for controlling media gateways on IP networks connected to the PSTN.
To complete our look at IP Telephony, let’s consider some of the advantages and disadvantages of using this kind of system.
As the conversation is running over a network connection, it is common that VoIP to VoIP calls have a very low cost.
If our VoIP activity takes place on a computer the VoIP software is usually available for free, which means the user only needs to buy a handset or headset to use. You can normally also just use the microphone and speakers built into every laptop.
You can use VoIP wherever you can use a mobile phone, as long as the device you’re using has the necessary capabilities. You can also use VoIP anywhere that you can connect to a wireless broadband connection.
However, the quality of the VoIP connection will depend heavily on the quality of the connection you have to the network. A poor connection will give you a poor VoIP experience.
Finally, the majority of VoIP services do not have the capability to encrypt your communications.
Having mentioned wireless networks, let’s now look at these is some more detail.
A wireless LAN (WLAN) is a local network that relies on radio waves to propagate data to end users. A WLAN is usually the final part of a network, allowing users to connect without having to physically connect. Once the data comes off the wireless network, it is usually carried on physical cables.
Although WLANs use a different medium for transmission, they still work in the same way as physical networks, using the same protocols at many layers of the OSI seven layer model.
While WLANs use many of the same protocols in the OSI model as a wired network, they do employ specialised protocols at the lowest layers. This makes sense, as it is at these layers that we see the big difference between wired and wireless networks – that is, wires or the lack thereof.
IEEE 802 11 is a set of standards for WLAN networking.
The demarcation point, meaning the point that is separated by distinct boundaries, between a wired network and a wireless network, is called the Access Point, or AP. In a corporate environment, there will often be a number of AP’s dotted around the premises, allowing users to stay connected to the network whilst moving around.
One thing to keep in mind is that a WLAN is far more open than a wired network. For a WLAN to work, it must broadcast its presence in some way so that devices can find and connect to it. This gives us extra security considerations – we need the WLAN to be available for use, but not to just anybody.
In order for us to connect to any network, we need a NIC. This is no different for a WLAN – we just need to use a NIC that has a radio transmitter/receiver.
Finally, any network connection is only ever going to run at the best speed of the slowest link. Wireless connectivity is usually slower than the speeds achievable on a wired network.
IEEE 802.11 is a set of standards for carrying out wireless local area network (WLAN) computer communication in the 2.4, 3.6 and 5 GHz frequency bands.
They are implemented by the IEEE LAN/MAN Standards Committee (IEEE 802).
Wi-Fi is a trademark of the Wi-Fi Alliance, a trade association that promotes Wireless LAN technology and certifies products if they conform to certain standards of interoperability; the main standards being IEEE 802.11 and associated sub-sets.
As a result, the term Wi-Fi has become synonymous with IEEE 802.11 networking.
The Wi-Fi Alliance is a trade organisation that tests and certifies equipment for use with the 802.11 WLAN standards. Over the years, new standards have been introduced that have increased data connection speeds and throughput, but also to address security issues of wireless communications:
- 802.11 was the original specification and operated in the 2.4Ghz band at speeds of 1-2Mbps. This specification is now obsolete
- 802.11a operates in the 5GHz band with a maximum net data rate of 54 Mbsps, plus error correction code, which yields realistic net achievable throughput in the mid-20 Mbsps
- The 5Ghz band is less congested than the 2.4Ghz band and so offers better data throughput, however this band is more readily absorbed by solid objects and so has a smaller usable distance
- 802.11b has a maximum data rate of 11 Mbps. This dramatic increase in throughput led to the rapid acceptance of 802.11b as the definitive wireless LAN technology in the early 2000s
- 802.11b devices do however suffer interference from other products operating in the 2.4GHz band – this includes microwave ovens, Bluetooth devices, baby monitors, cordless telephones and some amateur radio equipment amongst others
- 802.11g operates in the 2.4GHz band and offers a maximum bit rate of 54 Mbps exclusive of forward error correction codes, or about 22 Mbps average throughput
I have already mentioned that WLANs use a lot of the same protocols as wired networks, except at the lower layers of the OSI model.
The use of frames is one of the differences between the two.
As you can see on screen, there are three major frame types:
- Data frames do exactly what the name says they do. They are responsible for encapsulating and transporting data from one location to another
- Control frames facilitate in the exchange of data frames between stations
- Management frames allow for the maintenance or discontinuation of communication
It is no surprise that we are now starting to connect devices to the Internet, or our networks, that we would not think of as being some sort of computer. In fact, many of our household appliances do actually contain some limited computing power. For instance, a washing machine. How does it know how to execute any of the different wash programs it has available?
The details for these programs are stored on a circuit board within the device, and a very limited operating system executes them.
Given that even our washing machines are now computers of a sort, the step to connecting it to a network doesn’t seem quite so nonsensical!
The Internet of Things (IoT) is often described as the transformation of the Internet from a network-of-networks that connects end user devices and information to a network of networks which also interconnects many multiple types of devices.
In reality, the Internet of Things is much more than this, as the data produced by these 'things', can be used to create insights which can then be used to make decisions and drive actions.
IoT consists of a wide range of use cases, with some likely to become very complicated in the future.
It is widely believed that IoT will be a key business driver for communication services, as well as enterprises in the coming years.
More recently, the industry has created the term Massive IoT, or MIoT, referring to the connection of many devices and machines (potentially in the order of tens of billions) on a regular basis.
Alternatively, other IoT applications that require high availability, coverage and low latency, can also be categorised under Critical IoT; these applications could be enabled by 5G.
A third group could be called ‘enterprise applications’; these require a moderate bit-rate and mobility support. These Enterprise applications often use devices smarter than basic connected sensors.
With the evolution of M2M to IoT, different types of connectivity have become involved.
In addition to connecting more devices or machines, new value is being created by the data generated, for example, through big data analytics.
So how does something become a part of the IoT?
It is worth considering the elements that are used to construct an IoT service to understand the end-to-end picture of IoT.
It starts with a thing which is identified and addressed. Things exist in the physical world, so to transform them into a digital entity we need a sensor.
Next, you need to think about how to get the information about the thing to another device or service that will use this information.
There are a number of ways to communicate over the Internet, however, many devices are constrained. This means that they have limited processor power and limited memory.
The IoT requires new ways for devices to connect to networks, which has resulted in a new type of Area Network.
PAN stands for personal area network. It is a network covering a very small area, usually a small room. The best-known wireless PAN network technology is Bluetooth.
IoT devices can make good use of LAN technology, using Wi-Fi.
A Metropolitan Area Network, or MAN, allows the interconnection of devices or networks over metropolitan areas (towns or cities). The technology needs to be appropriate for the distance, for example, WiMAX or GSM.
Body Area Networks are now also available. These are usually medical devices attached or inserted into the human body. Many manufacturers are looking at low power networks which allow for intelligence to be embedded into many more things.
5G is a major leap forward for mobile networks so it is worth understanding it in further detail.
Work on International Mobile Telecommunications, or IMT has been happening for over three decades in the International Telecommunications Union, or ITU.
3G and 4G mobile broadband systems are based on the ITU’s IMT standards and they are increasingly becoming the primary means for accessing communication, information and entertainment.
Detailed specifications for IMT2000 (3G) have been in force since the year 2000, and the IMTAdvanced (4G/LTE) specifications were approved by the ITU Radiocommunication Sector (ITU–R) Radiocommunication Assembly in 2012 (RA12).
Fifth-generation 'IMT-2020' technology (5G) brings much faster data speeds, reliable connectivity and low latency to IMT, all of which are required for our new global communications ecosystem of connected devices sending vast amounts of data via ultrafast broadband.
It enables network connectivity with ultra-low latency, equal to less than one-tenth that of present communication systems.
It also makes massive connectivity possible, so that hundreds of thousands of devices can be connected to a cell simultaneously.
This is achieved by adopting new, more efficient and effective radiocommunications techniques and system architectures over a wide range of radio spectra, ranging from the traditional mobile communications bands into the emerging so-called 'millimeter wave' radio bands in the region above 6 GHz.
5G is not just redefining mobile services — it is also ushering in an era of open technologies that are transforming the telecommunications industry.
Software-defined networking (SDN) and Network Functions virtualisation (NFV) represent the future in telecommunications, by virtualising the infrastructure and services to offer unprecedented agility, intelligence, and openness.
For the past five years, SDN and NFV have been progressing due to unique collaboration between standards organisations and open-source communities that are together reshaping how new technologies are adopted.
WhatsApp is a texting service between mobile phones and can be considered a replacement for the regular SMS text messages. Over 900 million users are active worldwide using the WhatsApp service. WhatsApp uses an Internet connection between phones. The service is available for iPhone, Blackberry, Android and Nokia Symbian60-phones.
The major difference between regular SMS text messages and WhatsApp text messages is that WhatsApp is free: You use the Internet connection on your phone (Wi-Fi or part of your mobile data package depending on subscription or pre-paid type). WhatsApp is not restricted to sending text messages, you can also send pictures, videos, voice messages, contact information and share your current location.
In January 2015, WhatsApp introduced a voice calling feature; this helped WhatsApp to attract a completely different segment of the user population. On November 14, 2016, WhatsApp added a video calling feature for users across Android, iPhone, and Windows Phone devices.
Multimedia messages are sent by uploading the image, audio or video to an HTTP server and then sending a link to the content.
WhatsApp follows a 'store and forward' mechanism for exchanging messages between two users. When a user sends a message, it first travels to the WhatsApp server where it is stored. Then the server repeatedly requests that the receiver acknowledges receipt of the message. As soon as the message is acknowledged, the server drops the message; it is no longer available in the database of the server. The WhatsApp server keeps the message for 30 days in its database when it is not delivered (if the receiver is not active on WhatsApp for 30 days it discards the message).
FaceTime is available on supported mobile devices that run on iOS and Macintosh computers that run Mac OS X 10.6.6 onwards.
The video version of FaceTime supports any iOS device with a forward-facing camera, and any Macintosh computer equipped with a FaceTime Camera, formerly known as an iSight Camera.
FaceTime works by connecting any iPhone 4, fourth generation iPod Touch, iPad 2 or or a computer with OS X, to another supported device; Any later versions of these devices are also able to run FaceTime.
FaceTime is currently incompatible with non-Apple devices or any other video calling services.
Mac models introduced in 2011 introduced high-definition video FaceTime, which devices use automatically when both ends have a FaceTime HD camera.
Unlike Skype, a multi-person video chatting application, FaceTime specialises in one-to-one video.
For instance, Facetime will pause if you receive and read messages, emails, or other notifications.
Until the release of iOS 6, FaceTime required a Wi-Fi connection to work. From iOS 6 onwards, FaceTime for the iPhone and iPad has supported FaceTime calls over cellular networks (3G or LTE), provided the carrier has enabled it, which by mid-2013 virtually all carriers worldwide have allowed.
FaceTime Audio uses about three megabytes of data for every five minutes of conversation, with FaceTime Video using significantly more.
Cellular talk time or minutes are not used after switching from a voice call to a FaceTime call.
FaceTime calls can be placed from supported devices to any phone number or email address that is registered to the FaceTime service.
A single email address can be registered to multiple devices and a call placed to that address rings all devices simultaneously.
That brings us to the end of this video.