Basics of computer networks

Computer networks, a general term that covers a very wide range of technologies, protocols and methods. Many things in this area are taken for granted, which makes it difficult to find a simple description or logical inclusion in the whole puzzle that makes up the network. Today we will look at networks from a general global perspective, taking into account the interconnections. And in the next parts, we will get to know some areas from a practical point of view in more detail.

If we want to understand how communications work in computer networks, or networks in general, we have to start from the bottom. From a physical point of view, it is about cabling and basic active elements (switches), from a logical point of view, it is about communication at the smallest logical unit, i.e. within a subnet (direct communication). Both of these areas are defined and included in the Ethernet family of technologies.

In order to communicate on a computer network, we need to use some logical addressing that tells us what part of the network the participants are in. And then methods to ensure that the data is routed correctly from sender to receiver. In today's LANs, as in the Internet, this is the Internet Protocol (IP). For addressing, we use IP addresses and subnetting, and for forwarding data, we use routing.

Computer networks today are most often based on the TCP/IP family of protocols. From a physical and logical point of view, we do not use one global network, but a hierarchical division into different parts called subnets. In order for the individual subnets to communicate with each other, we must ensure the correct physical connection, but also allocate the correct address spaces. In the article, we will look together at IPv4 (Internet Protocol Version 4) addresses, how they are distributed and how they are calculated.