IPv4 vs IPv6: A Comprehensive Guide To The Two Internet Protocols

IPv4 vs IPv6: A Comprehensive Guide To The Two Internet Protocols

What is the Internet Protocol? What are the differences between IPv4 and IPv6? Continue reading to find answers to these and many other questions.

The article discusses the differences between IPv4 and IPv6, two versions of the Internet Protocol. It explains that IPv4 was first to be used widely, but its pool of unallocated addresses has since run out. In contrast, IPv6 offers an astonishing number of IP addresses and is slowly gaining adoption.

When IPv4 emerged, no one could have imagined the scale of the internet today. Unsurprisingly, as the internet expanded, the pool of unallocated IPv4 addresses drained fast, and in 2011, IANA (Internet Assigned Numbers Authority) officially exhausted its IPv4 free pool.

By this time, IPv6 was already introduced as an alternative with an astonishing number of IP addresses, but even today, the adoption of this version is surprisingly slow. IPv4 and IPv6 can coexist, but the former dominates the worldwide internet traffic.

To compare IPv4 vs. IPv6, we need to look at how these Internet Protocols emerged, what benefits they offer and what the main differences between IPv4 and IPv6 are.

What is IPv4?

IPv4 is a protocol that was introduced in 1981 and provides internet connections without requiring any contact between the two devices. Each IPv4 address consists of four blocks of octets written in decimal digits between 0-255, which represent unique bytes. There are 4,294,967,296 possible IPv4 addresses in total. However, due to depletion of resources 40 years later we may soon run out if transitioning to IPv6 does not go as smoothly as planned.

Back in the 1980s, 4.29 billion might have sounded like an unlimited number. Today, we are dealing with IPv4 exhaustion.

RIPE NCC, one of the five Regional Internet Registries that allocate internet number resources, ran out of IPv4 in November 2019. When the pools of IPv4 addresses drain, RIRs no longer have the resources to allocate or assign.

However, the need for IPv4 resources has not diminished. While IPv6 already offers a far greater number of unique addresses, the transition from IPv4 is not as smooth as imagined.

Benefits of using IPv4

The IPv4 infrastructure has been around for a long time and is now fully developed and optimized. It's the most popular IP version to identify devices, which we cannot say about IPv6 yet.

Users of IPv4 don't need to worry about upgrading their devices or finding experts who would take care of these upgrades - working with this Internet Protocol version 4 is something that network operators are used to and don't require additional training.

In the past, there were concerns that IPv4 wasn't as secure as IPv6. While that might have been true at one point, the security of the infrastructure has been upgraded so it's just as safe, assuming it's configured appropriately.

The benefits:

  • Set-in-place infrastructure

  • Fully optimized networks

  • Stable security

What is IPv6?

IPv6 stands for Internet Protocol version 6, and it is the newest version of the Internet Protocol. It was introduced in 1995 by the Internet Engineering Task Force, and the exhaustion of IPv4 addresses was already evident by this point. Although the logical sequence suggests that IPv5 would precede IPv6, the so-called Internet Stream Protocol was never fully deployed.

One address is 128 bit-long, and while the first 64 bits represent the network portion, the last – the host portion. An IPv6 address comprises eight groups written in hexadecimal format using values between 0 and FFFF and colons.

There are 340,282,366,920,938,463,463,374,607,431,768,211,456 (340 undecillion) IPv6 addresses in total. Needless to say, when we compare IPv4 vs. IPv6 by numbers, there is no comparison, and the size of this address space is much more suitable for today’s IoT world.

That said, although IPv6 has been around for quite some time, and we do not need to worry about exhausting IPv6 addresses – at least, not in the near future – the adoption of this Internet Protocol has been excruciatingly slow.

According to Google, the availability of IPv6 connectivity among Google users was over 37% in September 2021. This means that IPv4 continues to carry the internet.

Benefits of using IPv6

Complex configurations are the thing of the past with IPv6. While you need to assign IPv4 addresses for one system to communicate with other systems and perform firewall alterations, IPv6 offers stateless auto-configuration. During the process, the host finds an IPv6 router and requests a prefix, creates a link-local address and verifies that the address is unique.

The benefits:

  • More unique IP addresses

  • Stateless auto-configuration

  • Mobile network-friendly

IPv6 is the newest version of the Internet Protocol, introduced in 1995 to address IP address exhaustion. It offers more unique IP addresses and stateless auto-configuration, making it mobile network-friendly. The IPv6 infrastructure is ready for the IoT world's expanding needs.

Key differences between IPv4 and IPv6

IPv4 and IPv6 are both used to identify devices on a network and relay information, but they have several key differences. IPv4 has 4.29 billion addresses and uses 32-bit long numeric addresses, while IPv6 offers 340 undecillion addresses and uses 128-bit alphanumeric addresses.

Additionally, prefixes for IPv6 ranges from 1 to 128 digits compared to just 2 digits for IPv4. The header size is also different, with 40 bytes for IPv6 versus 20-60 bytes for IPv4. Finally, QoS (quality of service) is more efficient in IPv6 than it is in IPv4

The comparison

As you can see, when it comes to comparing IPv4 vs IPv6, there’s more than just the obvious numeric address vs alphanumeric address difference.

While both versions contain extension headers, the IP address header of each IP is different.

The comparison between IPv4 and IPv6 shows that there are many differences between the two versions of the protocol. Notably, extension headers are different, subnet masks are not used with IPv6, and NAT is not necessary with direct addressing. Additionally, DHCP is only used for obtaining IP addresses in an IPv4 network, while permanent addresses eliminate the need for a dynamic host configuration server in an IPv6 network. Finally, IPSec security is stronger with IPv6 and QoS handling is more efficient in networks using this version of the protocol.

The future of Internet Protocols

The outcome of the IPv4 vs. IPv6 battle is murky, even though some believe that IPv6 will become the standard Internet Protocol. In any case, we don’t know when IPv6 will catch up and, eventually, overtake IPv4 in implementation.

The future of IPv4

The future of IPv4 is uncertain, as the current IP addresses might run out soon. However, we still have ways to go before IPv6 becomes the standard Internet Protocol. While we wait for the technology and internet service providers to catch up, we can work with what we have - which is convenient and familiar.

Unfortunately, while IPv4 continues to be the convention, we are left dealing with the lack of IPs, which seriously hinders the growth of businesses across the globe. Buying or selling IPs might seem like the only logical step, but, in hindsight, not the most financially viable. Moreover, there are fewer and fewer opportunities to buy IPs.

Leasing is the gold standard for those wanting to monetize unused IP addresses and those in need of clean and reputable IPs. Lessors can turn their dormant IP addresses into profit, and lessees can use these unused IPs to scale their operations.

Reusing IP addresses helps build a sustainable internet that is not paralyzed by the lack of essential resources. Fortunately, plenty of IPv4 addresses are still unused.

The future of IPv6

While IPv6 may be the future of the internet, we don’t know yet when this future will come. Will we see IPv6 fully replace IPv4 by 2030? 2040? It isn’t reasonable to make such predictions at this time. At the end of the day, the advent of IPv6 is unlikely in the foreseeable future, and we have to find ways to create a sustainable internet with IPv4 today.

ISPs, mobile carriers and data centers will go on to fully adopt IPv6 at some point. However, right now, the costs and time required for full data migration are simply too high.

There’s also a lack of motivation to move from the existing infrastructure, especially since IPv4 and IPv6 can coexist. Dual IP stacking, tunneling and NAT-PT can help achieve that.

  • Dual IP stacking: Network hardware runs IPv4 and IPv6 simultaneously

  • Tunneling: IPv6 data packets are encapsulated within IPv4 packets

  • Network Address Translation-Protocol Translation: IPv4 packets are translated into IPv6 packets, or IPv6 packets are translated into IPv4 packets

All in all, IPv6 adoption is coming slowly but surely. Unsurprisingly, mobile networks are leading the way. In the US, T-Mobile is close to routing 100% of web traffic using IPv6, while AT&T and Comcast are close behind with 80% and 74% routing, respectively.

According to Google’s Per-Country IPv6 adoption statistics (September 2021), India is the number-one country in the world by IPv6 adoption at 62.82%, followed by Malaysia (54.56%), Germany (50.91%), Taiwan (48.39%) and Vietnam (48.58%). The US is currently at 45.75%.

The future of IPv6 is slowly but surely becoming a reality, with mobile carriers leading the way in terms of adoption. In India, Vietnam and other countries around the world, IPv6 adoption rates are steadily growing. However, there are still some challenges to overcome before it can become fully mainstream. One such challenge is transitioning from the existing infrastructure which currently relies on IPv4 - this process will require time and money that not all parties may be willing to invest.


IPv6 may replace IPv4 one day, but that isn’t happening tomorrow. While IPv6 might be more mobile-network friendly, mandate IP security and provide a lot more IP addresses, IPv4 continues to carry the internet today.

IPv4 addresses are running out, which is causing problems for companies that need them to scale their operations. Fortunately, there are still plenty of unused IPv4 addresses available, and businesses can rent them to help alleviate the shortage. Additionally, transitioning from IPv4 to IPv6 will require time and money that not all parties may be willing to invest in. However, we can create a sustainable internet using both protocols simultaneously until IPv6 eventually replaces IPv4.

As long as there are unused IPv4 addresses, there will be someone in need of them. Now is the perfect time to put dormant IPs to use and alleviate the global IPv4 shortage.