First and foremost, networks come in all sizes. They range from simple networks that consist of two computers to networks connecting millions of devices. Simple home networks let you share resources, such as printers, documents, pictures, and music, among a few local end devices. In this article, I want to discuss some facts about a network communication process.
Small office and home office (SOHO) networks allow people to work from home or a remote office. Many self-employed workers use these types of networks to advertise and sell products, order supplies and communicate with customers.
Businesses and large organizations use networks to provide consolidation, storage, and access to information on network servers. Networks provide email, instant messaging, and collaboration among employees. Many organizations use their network’s connection to the internet to provide products and services to customers.
The internet is the largest network in existence. In fact, the term internet means a “network of networks”. It is a collection of interconnected private and public networks.
In small businesses and homes, many computers function as both the servers and clients on the network. This type of network is called a peer-to-peer network.
Small Home Networks
Small home networks connect a few computers to each other and to the internet.
All computers that are connected to a network and that participate directly in network communication are classified as hosts. Hosts are also called end devices, endpoints, or nodes. Much of the interaction between end devices is client-server traffic. For example, when you access a web page on the internet, your web browser (the client) is accessing a server. When you send an email message, your email client will connect to an email server.
Servers are simply computers with specialized software. This software enables servers to provide information to other end devices on the network. A server can be single-purpose, providing only one service, such as web pages. A server can be multipurpose, providing a variety of services such as web pages, email, and file transfers.
Client computers have software installed, such as web browsers, email clients, and file transfers applications. This software enables them to request and display the information obtained from the server. A single computer can also run multiple types of client software. For example, a user can check email and view a web page while listening to internet radio.
- File Server – The file server stores corporate and user files in a central location.
- Web Server – The web server runs web server software that allows many computers to access web pages.
- Email Server – The email server runs email server software that enables emails to be sent and received.
The figure shows a switch with wired computers connected to it. The top computer is a file client and to the right of it is the file server. Besides the file, the client is number one. The associated words are as follows: The File Server stores corporate and user files in a central location. The client devices access these files with client software such as windows explorer. There are also a computer labelled web client and a web server. The number 2 beside the web client has the following words: The Web Server runs webserver software and clients use their browser software, such as Windows Internet Explorer, to access web pages on the server. There is an email client computer and an email server. The email client has the number 3 beside it with the following words: The Email Server runs email server software and clients use their mail client software, such as Microsoft Outlook, to access email on the server.
A typical network user at school, at home, or in the office, will normally use some type of computing device to establish many connections with network servers. Those servers could be located in the same room or around the world. Let’s look at a few typical network communication sessions.
Terry is a high school student whose school has recently started a “bring your own device” (BYOD) program. Students are encouraged to use their cell phones or other devices such as tablets or laptops to access learning resources. Terry has just been given an assignment in language arts class to research the effects of World War I on the literature and art of the time. She enters the search terms she has chosen into a search engine app that she has opened on her cell phone.
Terry has connected her phone to the school Wi-Fi network. Her search is submitted from her phone to the school network wirelessly. Before her search can be sent, the data must be addressed so that it can find its way back to Terry. Her search terms are then represented as a string of binary data that has been encoded into radio waves. Her search string is then converted to electrical signals that travel on the school’s wired network until they reach the place at which the school’s network connects to the Internet Service Provider’s (ISP) network. A combination of technologies takes Terry’s search to the search engine website.
For example, Terry’s data flow with the data of thousands of other users along with a fibre-optic network that connects Terry’s ISP with several other ISPs, including the ISP that is used by the search engine company. Eventually, Terry’s search string enters the search engine company’s website and is processed by its powerful servers. The results are then encoded and addressed to Terry’s school and her device.
All of these transitions and connections happen in a fraction of a second, and Terry has started on her path to learning about her subject.
Michelle loves computer games. She has a powerful gaming console that she uses to play games against other players, watch movies, and play music. Michelle connects her game console directly to her network with a copper network cable.
Michelle’s network, like many home networks, connects to an ISP using a router and a cable modem. These devices allow Michelle’s home network to connect to a cable TV network that belongs to Michelle’s ISP. The cable wires for Michelle’s neighbourhood all connect to a central point on a telephone pole and then connect to a fibre-optic network. This fibre-optic network connects many neighbourhoods that are served by Michelle’s ISP.
All those fibre-optic cables connect to telecommunications services that provide access to the high-capacity connections. These connections allow thousands of users in homes, government offices, and businesses to connect internet destinations around the world.
Michelle has connected her game console to a company that hosts a very popular online game. Michelle is registered with the company, and its servers keep track of Michelle’s scores, experiences, and game assets. Michelle’s actions in her game become data that is sent to the gamer network. Michelle’s moves are broken up to groups of binary data that each consist of a string of zeros and ones. Information that identifies Michelle, the game she is playing, and Michelle’s network location are added to the game data. The pieces of data that represent Michelle’s game play are sent at high speed to the game provider’s network. The results are returned to Michelle in the form of graphics and sounds.
All of this happens so quickly that Michelle can compete with hundreds of other gamers in real-time.
Dr. Ismael Awad is an oncologist who performs surgery on cancer patients. He frequently needs to consult with radiologists and other specialists on patient cases. The hospital that Dr. Awad works for subscribes to a special service called a cloud. The cloud allows medical data, including patient x-rays and MRIs to be stored in a central location that is accessed over the internet. In this way, the hospital does not need to manage paper patient records and X-ray films.
When a patient has an X-ray taken, the image is digitized as computer data. The X-ray is then prepared by hospital computers to be sent to the medical cloud service. Because security is very important when working with medical data, the hospital uses network services that encrypt the image data and patient information. This encrypted data cannot be intercepted and read as it travels across the internet to the cloud service provider’s data centres. The data is addressed so that it can be routed to the cloud provider’s data centre to reach the correct services that provide storage and retrieval of high-resolution digital images.
Dr. Awad and the patient’s care team can connect to this special service, meet with other doctors in audio conferences and discuss patient records to decide on the best treatment that can be provided to the patient. Dr. Awad can work with specialists from diverse locations to view the medical images and other patient data and discuss the case.
All of this interaction is digital and takes place using networked services that are provided by the medical cloud service.
Tracing the Path
We tend to think about the data networks we use in our daily lives as we think about driving a car. We do not really care what happens in the engine as long as the car takes us where we want to go. However, just like a car’s mechanic knows the details of how a car operates, cybersecurity analysts need to have a deep understanding of how networks operate.
When we connect to a website to read social media or shop, we seldom care about how our data gets to the website and how data from the website gets to us. We are not aware of the many technologies that enable us to use the internet. A combination of copper and fiber-optic cables that go over land and under the ocean carry data traffic. High-speed wireless and satellite technologies are also used. These connections connect telecommunications facilities and internet service providers (ISP) that are distributed throughout the world, as shown in the figure. These global Tier 1 and Tier 2 ISPs connect portions of the internet together, usually through an Internet Exchange Point (IXP). Larger networks will connect to Tier 2 networks through a Point of Presence (PoP), which is usually a location in the building where physical connections to the ISP are made. The Tier 3 ISPs connect homes and businesses to the internet.
Because of different relationships between ISPs and telecommunications companies, traffic from a computer to an internet server can take many paths. The traffic of a user in one country can take a very indirect path to reach its destination. The traffic might first travel from the local ISP to a facility that has connections to many other ISPs. A user’s internet traffic can go many hundreds of miles in one direction only to be routed in a completely different direction to reach its destination. Some of the traffic can take certain routes to reach the destination, and then take completely different routes to return.
Cybersecurity analysts must be able to determine the origin of traffic that enters the network and the destination of traffic that leaves it. Understanding the path that network traffic takes is essential to this.
I know you might agree with some of the points that I have raised in this article. You might not agree with some of the issues raised. Let me know your views about the topic discussed. We will appreciate it if you can drop your comment. Thanks in anticipation.
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