As the name implies, IPv4 or Internet Protocol version 4 is the fourth version of the IP or Internet Protocol. This protocol is one of the core protocols used in establishing and maintaining the Internet (as well as some other similarly structured networks).
The original version of the IP was introduced in 1974. Long before the Internet we currently know became established. It also served as the basis of another protocol – the TCP. Or Transmission Control Protocol. Unlike the TCP, which was updated but not majorly reworked since its conception, the IP has seen several revisions. IPv4 was the first major version of it and is, to date. Still, the dominant protocol is used on the Internet.
What Does It Do?
The Internet Protocol, in any version, is responsible for fragmenting and reassembling transmitted data and routing datagrams from host to destination. More simply, IPv4 breaks down the information and packages it into smaller units that can be transferred via the network. And then does so before putting the data back together for the recipient. “Datagram” is the network packets sent back and forth. And each of them is made up of two sections – the header and the payload.
The IP header contains information about the source and destination IP address and additional metadata needed to get the datagram to where it’s going. The payload is the actual data that is being transported. The process of breaking down data into datagrams for transfer is done billions of times daily. Every time a user accesses the Internet and requests to load a webpage, for example.
The original IP created in 1974 wasn’t sufficient for the task that first required its use. In 1981, IPv4 was developed as an improved version. It was this version that the US Department of Defence adopted as the standard for all their military computer networking. Thus, it became a cornerstone of the modern Internet not long after.
The format used for addresses within the IPv4 system consists of four octets of data, most often separated by dots. The design is familiar to most people: 127.0.255.250 would be an example of one such address. It’s worth noting that IP addresses in the IPv4 system aren’t the same as website URLs – although website content is transmitted via the IP protocol, URLs and IP addresses aren’t synonymous. While a phone used to load a website has a unique IP address, the website itself does not – whatever computer the data is stored on, however, does.
Limitations and the Next Step
The purpose of IPv4 is exclusively to get data from A to B – it doesn’t guarantee data delivery, nor does it make sure that information is delivered and assembled in the correct order and at the right time. It also can’t prevent duplicate packets from being sent. Things like that are necessary but are taken care of by upper-layer transport protocols, such as the TCP. All IPv4 does, is take a ‘best-effort’ approach to deliver as much data as possible to the correct location. In contrast, essential aspects such as data integrity are handled by other protocols.
IPv4s most significant limitation is its use of 32-bit addresses. Back at its inception, that wasn’t an issue. The Internet has expanded to a point where address space exhaustion is an issue. The 32-bit addressing system means the total number of possible addresses is 232. In other words, only 4294967296 addresses can exist.
About 18 million of those are reserved for private networks, and another 270 million for multicast addresses – but either way, the Internet is rapidly reaching the point where this number isn’t enough anymore. This prompted the development of a successor protocol – IPv6. In 2011, the primary address pool was formally exhausted, leaving only a tiny space to transition to IPv6.
IPv6 was first proposed in 1998 and ratified as an Internet standard in 2017, long after it started being used by developers in the mid-2000s. Despite being an improvement as far as address spaces go (IPv6 uses 128-bit packets, totaling 3.4×1038 available addresses), IPv4 and IPv6 aren’t interoperable. This means they can’t communicate with each other directly. This also makes it more complicated to transition entirely to IPv6 and is why so much of the Internet is still wholly reliant on the IPv4 system.
IPv4 is the foundational protocol and addressing scheme of the Internet and its precursors. Like many aging protocols, however, it shows signs of outdated design. While for many protocols, this has been a lack of security, for IPv4, it’s a lack of scalability. While the 4 billion addresses it offers may sound like a lot, in the modern world where many people have more than one internet-connected device, it’s simply not enough.
Despite this and the intense pressure to move to the successor IPv6 protocol which provides a vast address space, it has been relatively tricky and slow to transition away from IPv4. Even now, many networks that utilize IPv6 either use dual network stacks involving IPv4 and v6 or use IPv4 internally and translate it via NAT to an IPv6 public address.