This is easiest to explain through an example. With just two numbers (network IP and subnet mask), you can calculate the number of available IP addresses for new devices on your network. In other words, your ISP assigns a single IP address for your network which has X number of IP addresses available for new devices. Rather than your ISP assigning a new IP address for each device that is added to your network, they just give you an "address space". To solve this problem, the concept of subnetting came into existence. I'm sure the engineers working on it didn't think we would ever reach 4.2 billion addresses, but they had a suspicion that if they weren't conservative with the assignments of new addresses, it would not only become a scarce resource, but also a pain in the butt to manage. When IPV4 was invented, it was clear that the IP address space needed to be conserved. Our goal in this post is to understand how each device on your network receives a unique address despite the fact that your ISP only provided you 1 IP address to start with. You will want to look for the entry that shows a "inet" address. To find your computer's IP address, you can type ipconfig into a Windows terminal or ifconfig into a Mac/Linux terminal. With IPV6, we have 1.8x10^19 addresses (2^64), which will never pose a capacity issue. This seems like a large number, but with a world population between 7 and 8 billion, you can see how this could be constraining. If you calculate how many combinations you can have with 32 bits, it is 4.2 billion (2^32). The reason we need IPV6 addresses is because we are running out of the former. Today, most IP addresses are IPV4 addresses, which means that they are 32 bit rather than 64 bit IPV6 addresses. I am assuming that most people reading have an idea what an IP address is, but as a refresher, an IP address is a 32 bit number that identifies a specific network or computer. You will soon understand what this means in full, but for now, just know that your entire home network is represented as a single IP address. Your ISP assigns you ONE IP address, and ONE Subnet mask. Before reading one more word, you need to remember one important fact. ![]() ![]() And this is where the fun begins, because the router has a lot of responsibility for making your home network functional. The modem takes that analog signal, converts it to a digital signal, and sends it over to the router. The signals traveling through the telephone wires your ISP owns are analog signals (wave frequencies), while your computer runs on digital signals (1s and 0s). Regardless the method your ISP uses to get internet to your home, you will always be faced with the same problem. Previously, you had to use "dial up" where you would literally "call in" through the phone line to access the internet. We call this "broadband" and it is the reason we can talk on the phone, watch Netflix, and search the web all at the same time. The internet bootstrapped off of the phone system, and nowadays, there are multiple channels of communication running through each telephone wire. The method of telephone wires often confuses people because given the name, you would assume that only telephone signals can be sent through telephone wires. ![]() Other methods include underground cables and dish satellites. There are multiple ways that internet can reach your home, but the most common is through telephone wires (UTP cables). Fiber optic cables (fastest type - many are in the ocean).Unshielded twisted pair (UTP) cables (100 Mhz).Coaxial cables (what you have in your house).What are these wires we speak of? Many ISPs own a variety of hardware that all are capable of carrying the analog signals we know as the "internet". An ISP is simply a company that owns hardware (wires) and makes that hardware available to customers in the form of internet service. ISPs are confusing in many cases because they offer more than one service, but in the scope of this post, let's consider an ISP that offers only internet as a service. The first thing we need to understand is what an internet service provider actually does. In this post, whether you are a seasoned engineer or simply a Dad trying to figure out why the router isn't working again, I will explain the basics of how your home network works. For most home users, trying to understand a home network is not of interest due to the perceived complexity of the issue.
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