IPv4

Computers use special numbers to talk.

These numbers work like home addresses. They help data find the right place.

There are about four billion of these numbers. This sounds like a lot! But many people use the web now. More people mean we need more numbers.

Soon, we ran out of these special numbers. This is called exhaustion. We are now moving to a new system.

This new system has many more addresses.

It helps all our devices stay connected. It is a big change for the web. We are building a bigger home for data.

Computers use a system to talk to each other. This system is called IPv4. It works like a mailing system for data.

Every device gets a special number. This is called an IP address. These numbers help data find its way.

IPv4 uses 32-bit addresses. This means there are about 4.3 billion unique numbers.

Most addresses look like four numbers with dots. For example, 192.168.0.1 is an address.

But there is a problem. The world is running out of these numbers. This is called address exhaustion. More people use the web every day. We have many new tools like smartphones.

These devices all need their own numbers.

To help, we use new tools. One tool is called NAT. It helps many devices share numbers. We are also moving to a new system. This is called IPv6. It has a much bigger pool of numbers. This will help the internet keep growing.

IPv4 is a very important system for the internet. It is a set of rules called a protocol. This protocol lets different computer networks talk to each other.

It works at the internet layer of the Internet Protocol Suite. This layer gives the internet a way to label everything. Every device gets a unique logical address. This address helps data find its way across the world. Without these addresses, computers would not know where to send information.

How does this system actually work? It uses a method called best-effort delivery. This means the protocol sends data packets but does not guarantee they arrive. It also does not promise they arrive in the right order.

To fix these issues, other protocols like TCP are often used. IPv4 uses 32-bit addresses to identify devices. These addresses are usually written as four numbers separated by dots. For example, 192.168.0.1 is a common way to write one. This is called dot-decimal notation.

People have been working on this system for a long time. In 1981, a document called RFC 791 described IPv4. Before this, the rules for TCP and IP were combined. In March 1982, the US Department of Defense chose this suite. They made it the standard for all military computer networking.

IPv4 was first used on SATNET in 1982. Later, it was used on the ARPANET in January 1983. These early steps helped build the modern internet we use today.

There are many specific facts about these addresses. IPv4 provides about 4,294,967,296 unique addresses. However, many of these are set aside for special tasks. For instance, about 18 million addresses are for private networks.

These private addresses cannot travel on the public internet. On February 3, 2011, the main pool of addresses was exhausted. This means the Internet Assigned Numbers Authority ran out of them. This happened because there were so many new users and devices.

Running out of addresses is a big challenge. This problem is called IPv4 address exhaustion. As more people got smartphones and laptops, the numbers went fast.

To help, engineers created tools like NAT. NAT lets many devices share numbers to save space. The long-term solution is a new system called IPv6. IPv6 was specified in 1998 to provide much more space. It allows for a huge amount of new addresses for everyone.

Internet Protocol version 4, or IPv4, is a fundamental set of rules for digital communication. It serves as a standalone specification for internetworking across packet-switched networks.

As a core protocol, it enables the Internet Protocol Suite to function at the internet layer. Its primary job is to provide a global-scale logical addressing system. This system allows data packets to travel from a source host to a specific destination. The protocol guides these packets through routers, moving them one hop closer to their goal with each step.

IPv4 operates using a connectionless model known as best-effort delivery. This means the protocol sends data packets without guaranteeing they will arrive at their destination. It also does not ensure that packets arrive in the correct sequence or prevent duplicate deliveries. To manage these potential issues, engineers use upper-layer transport protocols. Examples include the Transmission Control Protocol (TCP) or the QUIC protocol, which handle reliability.

Every device in an IPv4 network requires a unique identifier. These identifiers are 32-bit addresses, which provide a total address space of 4,294,967,296 unique addresses.

Because these addresses are binary, they are often written in dot-decimal notation. This notation uses four octets, which are groups of numbers, separated by periods. For instance, an address might look like 192.168.0.1. Another way to write these is through CIDR notation. This method uses a slash and a number to show the routing prefix in a compact format.

Historically, the development of IPv4 changed how computers connected. Earlier versions of the protocol were combined with TCP in a single specification called TCP/IPv3. In September 1981, the IETF published RFC 791, which established IPv4 as its own separate specification. This replaced an earlier definition from January 1980. In March 1982, the US Department of Defense adopted the TCP/IP suite as the standard for all military networking. IPv4 saw its first production deployment on SATNET in 1982, followed by the ARPANET in January 1983.

As the internet grew, the way addresses were assigned also evolved. Originally, the address was split into a network identifier and a host identifier. This old system only allowed for 256 network identifiers, which was not enough. To fix this, engineers introduced classful networking in 1981. This system created five different classes, such as Class A, B, and C, to provide different capacities for hosts. Later, in 1993, Classless Inter-Domain Routing (CIDR) was introduced. CIDR allowed for much more flexible repartitioning of address space for users.

By the late 1980s, experts realized the pool of IPv4 addresses was depleting too quickly. This was not expected in the original design. In the 1990s, market forces accelerated this depletion. More people began using mobile computing devices like laptops, PDAs, and smartphones. High-speed, always-on internet access also increased the demand.

This led to a crisis called IPv4 address exhaustion. To slow this down, technologies like Network Address Translation (NAT) were used. NAT allowed many devices to share addresses, which helped preserve the limited supply.

Specific blocks of addresses are reserved for special purposes rather than general use. For example, about 18 million addresses are set aside for private networks.

These private addresses are not routable on the public internet. Other blocks are used for multicast traffic, which involves sending data to a group of recipients. The IANA maintains the primary address pool, and they officially exhausted the main pool on February 3, 2011. This exhaustion prompted the transition to IPv6, a successor designed with a much larger address space. While IPv6 is the long-term solution, IPv4 remains vital for routing much of today's internet traffic.