40 Years of IPv4 Legacy and Learnings Pave the Way for IPv6

30/09/2021

IPv4, the IP protocol that popularized the Internet and allowed it to become a global network, is turning forty. While experts value the contributions and insights of four decades of IPv4, they agree that the time has come for massive IPv6 deployment to take us into the future.

In this interview, Carlos Martínez, LACNIC CTO and a global technical community leader on Internet issues, reviews the history of IPv4, shares the details of its creation, and advocates for a future with IPv6.

How did the IPv4 protocol originate? How do you assess the creation of IPv4 forty years ago and the four decades during which the protocol has been in operation?

The IPv4 protocol evolved out of the previous network protocol, which was not called IPv3. The name of previous protocol was Network Control Program (NCP) and it combined the functions of what we now know as IP and TCP in a single protocol. One of the most important lessons we learned back then was that this was not a good idea, which is why IP and TCP were developed as two separate protocols.

Today, we can appreciate the value of this lesson when we see that an ISP can enable IPv6 for its customers and the change is practically transparent to their users. If this lesson had not been learned, we would now be thinking about changing TCP or the equivalent function, and the entire process of transitioning to IPv6 would be much more complex.

IPv4 was able to scale to a global network. It gave us the possibility of having the Internet we have today. It is a scalable protocol and good enough to allow us to watch movies and make video calls without giving too much thought to what is going on in the network. IPv4 came into operation when typical Internet speeds were measured in hundreds of bits per second, and it continues in use now that typical speeds are measured in hundreds of millions of bits per second.

IPv4 holds a series of very valuable lessons for those designing new protocols. A key lesson is the one I mentioned above: the clear separation of responsibilities. Thinking about how to extend a protocol without having to change everything was a clear opportunity for improvement. Developers learned this lesson well and implemented these teachings in subsequent designs such as DNS and HTTP, two protocols that can easily be extended.

IPv4 has evidently allowed the Internet to grow, yet it is finite. Does this mean that IPv4 might be considered obsolete in light of IPv6?

I don’t like to use the term ‘obsolete’ to describe something that still works. I think the term ‘legacy’ is a better choice. If society had not adopted the Internet as a key part of its day-to-day life, if the Internet had remained a niche service for academia and governments, then IPv4 would still be good enough.

IPv6 is the element we need today to take a leap into the future and allow the Internet to continue to operate as we know it today.

Could it be that the delay in deploying IPv6 is triggering interest in the ‘few’ globally available IPv4 addresses and increasing the use of transition mechanisms?

The delay in IPv6 content deployment places pressure on operators, but there is also a certain inertia, the habit of using the previous protocol and, in some cases, the need to upgrade equipment and management systems. All this increases interest in the extremely few remaining IPv4 addresses.

This behavior is not exclusive to IPv4 or to the Internet and there are multiple examples of this with various technologies and in different industries. There is an inflection point after which the cost of continuing to operate with the legacy technology outweighs the cost of incorporating the new one, and this is gradually leading more and more operators and content providers to deploy IPv6.

In your opinion, do small businesses have the resources required for IPv6 deployment? Are large businesses motivated enough to undertake this transition?

I don’t think there is a universal answer to these questions. I think there are actually multiple other relevant factors, such as the current Internet penetration levels in each country, the economic situation, the ability to invest.

Small operators have some important advantages (less equipment to convert, simpler processes, the possibility of using open-source routing solutions), but also some disadvantages (smaller staff, less capital). They have an important incentive to have their own numbering resources, which is having their own routing policies to access IXPs and CDNs. Operators who do not have IPv4 must necessarily aim to do this with IPv6.

Large operators have other incentives, but their cases can be very different. Some Brazilian and Mexican operators have managed to achieve very large IPv6 deployments in a remarkably short amount of time.

Following up on the previous question, LACNIC conducted a study this year. What were the main conclusions of this study in relation to the situation five years ago?

The obstacles to IPv6 deployment have changed. In 2016, the first cause mentioned by survey respondents was the lack of IPv6-enabled CPEs (the devices installed by operators in their clients’ homes, in other words, modems or routers as users know them). In 2021 this cause was still mentioned, but it did not top the list and was not considered a pressing issue.

In 2021, the list of obstacles mentioned by survey participants was topped by the need to adapt Operational Support Systems (OSS) and Business Support Systems (BSS), two key pieces of software essential for Internet operation, both for enabling new services as well as for business operations towards customers.

How is the LatAm region doing in relation to the rest of the world in terms of IPv6 deployment and penetration? How do you see its evolution in the coming years?

The IPv6 adoption level in Latin America is similar to the world average: approximately 30% or one in three users can access content over IPv6. However, significant asymmetries persist among the different countries of the region.