Computer Networks

My goal was to focus on practical things that people encounter daily, in contrast to the way networks are discussed at university. However, I still wanted to start from the very basics. After the general introduction, I mainly focused on local area networks (LANs).

• Computer networks and their types. To talk about computer networks, we need to define what this term means and how we can classify computer networks.
• Computer networks - basic topology. When creating a computer network, the elements are connected in different ways based on the technology, and we use a certain network topology.
• OSI model. The ISO OSI model is used to describe communication in a computer network, utilizing a system of layers, where only adjacent layers can communicate with each other.
• Ethernet - CSMA/CD, collision domain, duplex. In LAN networks (and often in larger ones as well), the Ethernet technology is predominantly used (compared to others like Token Ring and FDDI). This article describes the basic principles of Ethernet and how it accesses the physical medium, i.e., how it communicates.
• TCP/IP - model, encapsulation, packet vs. frame. The TCP/IP protocol is the dominant protocol in Ethernet networks. This protocol is described using the TCP/IP model, and during transmission, a process called encapsulation of the individual layer data is performed. This article provides an introduction to TCP/IP, along with the model, a description of encapsulation, and the frame (which refers to Ethernet) and packet format.
• TCP/IP - data transmission methods. If we want to send data using TCP/IP, we must first choose the right transmission method, depending on whether we are addressing one or more recipients.
• TCP/IP - addresses, masks, subnets and calculations. The TCP/IP protocol uses IP addresses and subnet masks for addressing, which are used to divide the network into logical blocks - subnets. The description of these terms, along with calculation methods, can be found here.
• VLAN - Virtual Local Area Network. Another significant helper in the logical division of the network into smaller parts are virtual local area networks - VLANs.
• TCP/IP - connection establishment and termination. Communication in TCP/IP always starts with establishing a connection and ends with a prescribed method.
• TCP/IP and Ethernet - network path, active network elements. If I want to send data to another station, I must address it correctly, using the correct physical address (MAC - based on Ethernet) and logical address (IP from the TCP/IP protocol). The communication protocol takes care of most things automatically, but it's good to know how it works and how data travels through the network. This also depends on the active network devices in the path.
• TCP/IP - Routing. If data is transmitted between different subnets (networks), it must pass through a router or other device that performs routing. There are a variety of routing protocols.
• TCP/IP - finding MAC address to IP - ARP. Some other protocols are important for communication in the network, such as ARP for finding the MAC address for an IP address, DHCP for dynamically assigning IP addresses to stations, and DNS for translating IP addresses to domain names and vice versa. A brief explanation of the ARP protocol principle is provided here.
• DNS (Domain Name System) focused on Microsoft. This article slightly deviates from the concept of the series, but its content fits in. A crucial component of TCP/IP, which translates easily memorable domain names to IP addresses, is essential for the functioning of the Internet.