The Challenges of Migrating from IPv4 to IPv6

IPv6 has noteworthy challenges to overcome when transitioning from IPv4. What are some main resistance against IPv6 adoption?

It was just about twenty years ago that I began delving into the world of networking.  It was then that I first started studying to get my CCNA certification, and of course, the focus of the content, at least as far as Layer 3 protocols go, was indeed IPv4.

As I think back, I don’t even remember if I was even vaguely aware of the existence of IPv6 at the time.  You may say well, of course not. That was twenty years ago! 

And yet, IPv6 is not as young as we may be led to believe.  The original protocol was defined in RFC 2460 way back in December of 1998!  That means that at the time of this writing, IPv6 is turning 22 this month! 

Despite its significant improvements, its vast scalability, as well as its expected longevity, IPv6 still has several noteworthy challenges that must be overcome when transitioning from IPv4. 

These are not all inherent to IPv6 itself but also to a series of seemingly unrelated factors that, together, form the main resistance against IPv6 adoption.

So why the delay?

IPv6 has been around for almost a quarter of a century (an eternity in telecom years) and has yet to surpass the threshold of a 40% adoption rate on the Internet, according to Google.

There are many reasons for this, and the unexpected truth is that many of the most significant are not technical

I’d like to showcase some of the most prominent obstacles in an attempt to help you understand them and to be able to overcome them more easily in your particular implementations and experience.

Technical obstacles

OK, there are some technical obstacles that have contributed to the relative delay of IPv6 adoption, so let’s start with these first.

IPv4 is very well designed

If you were surprised that IPv6 is around the age of a young adult, you might be astonished to find out that IPv4 is comparatively middle-aged, having been first defined in RFC 791 in September of 1981. 

The reason for IPv4’s successful operation for over four decades is simply the fact that it was designed so well.  Rarely will you find telecom protocols with such longevity.  And remember, IPv4 isn’t going anywhere anytime soon, so expect it to be around still when it enters its sixth decade of existence.

Arguably, IPv6’s greatest enemy is IPv4’s great design.  This, along with several innovative and very effective technologies such as NAT, has suppressed and delayed the need for migration, greatly slowing the transition process.


When new protocols and technologies are developed, many maintain some level of backward compatibility.  For example, Wi-Fi 6, which is defined by the IEEE 802.11ax standard, is backward compatible with previous iterations of the technology, including 802.11g/n/ac. 

Conversely, IPv4 and IPv6 are fundamentally incompatible.  Designers and engineers opted to completely redesign the architecture of the protocol to deliver the required performance and capabilities, resulting in two mutually exclusive protocols

This means that during migration, mechanisms must be put into place that enables communication between IPv4 and IPv6 networks. 

Of course, several very effective transition mechanisms have been defined and developed for this purpose. However, this does introduce a level of complexity to existing networks – complexity that many network administrators would rather not have to deal with.

IPv6 transition mechanisms

Many have developed methodologies that can be used to aid in the transition process between the use of an IPv4 and IPv6 network.  Some of these have been defined in RFCs to be used by multiple vendors, while others have been conjured up to be used by specific equipment. 

As mentioned before, these mechanisms do introduce complexity to a network.  But that’s not the only issue.  There seem to be many mechanisms that are similar and differ slightly in some nuanced way.

For example, we have IPv6 Rapid Deployment (6rd), there’s 6in4 tunneling, and there’s also 6to4, which is a translation mechanism intended to be used temporarily as a transition mechanism. 

Now, these mechanisms are, of course, there to act as an aid to transition and not an obstacle.  However, I have found from experience that many of these mechanisms have performed under par, and many administrators and decision makers are loth to employ them in their production networks.

Administrative obstacles

As mentioned above, many of the most significant challenges involved with the adoption of IPv6 are more administrative rather than technical.  These are further described below.

Network administrator bias

I must admit that when I first started dealing with IPv6, it felt weird.  I didn’t like it, to be honest.  I was so comfortable and familiar with the dotted decimal format of IPv4, and I had learned all of the subnet masks and subnet sizes by memory, simply from experience.  IPv4 seemed so easy, while IPv6 appeared so foreign.  I mean, look at this:

It looks very familiar, almost comforting!  And now, look at this:


It just looks like some incomprehensible alien writing, doesn’t it?  But like with anything else, there is a learning curve, and if that learning curve is overcome, I can tell you from experience that IPv6 turns out to be easier to work with.  No, it does, really!  No more need for variable subnet masks or running out of addresses. 

Due to the vast address space that is made available, creating an IPv6 address scheme for an enterprise is much simpler with IPv6 rather than with IPv4. 

Now, this learning curve is not just limited to addressing format and subnetting but also deals with relearning how to implement routing protocols, multicast, security features, as well as any transition mechanisms you may need to apply, all from the point of view of IPv6.  Even the way network devices behave changes with IPv6.

So, it is indeed no easy task and does present a challenge; however, in the end, it is well worth the effort to learn and apply these changes within the framework of a migration plan.

Current Installation base

One of the things that most decision-makers involved in choosing when to migrate to IPv6 consider is, “do I need to do it now, or can it wait?” 

This need primarily depends upon whether or not the networks you are connecting to (ISP, WAN, partner networks, etc.) require you to use IPv6 (or some related transition mechanism) or if they are content to serve your IPv4 infrastructure.

As my ancestors, the ancient Greeks used to say: “ανάγκα και θεοί πείθονται.”  Need I say more?  Well, I guess a little more would help!  It means “when there is a need, even the gods are persuaded.”  When the need to transition to IPv6 is dire, even the networking gods are persuaded to do so

The great obstacle, in this case, is that there is such a huge IPv4 installation base that no one absolutely needs to migrate, and few are investing the time, money, and effort to be among the first to do so. 

So, if your enterprise can still operate using IPv4 and they don’t need to migrate, in the vast majority of cases, they won’t.

The important takeaway here is to evaluate this need accurately and to ensure that your migration takes place well before the need is dire so that you won’t be praying to the networking gods for help when all your interconnecting networks have already migrated to IPv6.


Among the most difficult obstacles to overcome, in any situation, is the cost of a migration.  For many, especially budget-conscious businesses that can’t afford unnecessary expenditures, currently transitioning to IPv6 is not an option. 

Since IPv4 is still alive and kicking and will be around for years to come, those organizations that don’t have the financial power to do so will be among the last holdouts keeping their IPv4 network up and running. 

Unless their ISP or network equipment vendor stops supporting IPv6, it is unlikely that such entities will move to the new protocol.


As the world moves from IPv4 to IPv6, it is undergoing one of the most elementary and radical migration processes observed in the modern world.  It may sound like I’m being unnecessarily grandiose, but I choose my words specifically.  Such a fundamental change in the communication fabric of the world is no simple matter and, as such, cannot occur overnight.  

Nor, apparently, can it occur in a decade.  However, it will take place, and we will see the benefits of this fundamental shift in the coming years and decades.  I count myself fortunate to be a part of it, as I believe should every network engineer that is active today.

Lazaros Agapidis

Lazaros Agapidis

Lazaros Agapidis is a telecommunications and networking specialist with over twenty years of experience in network design, architecture, deployment, and management. He’s worked with multiple wired and wireless technologies including IP networks, fiber optics, Wi-Fi, as well as mobile communication networks. He has developed training content and courses for multiple vendors, and has been directly involved with teaching telecommunications for more than a decade. Over the years, he’s gained valuable first-hand experience from working on various large-scale telecom projects from both the enterprise as well as the telecom provider point of view.

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One comment

  1. The ISPs have been glacier in their adoption of IPv6 and why I feel that it has hurt its widespread implementation. Comcast supports IPv6, but their implementation is difficult, especially for business customers, to configure.

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