Transitioning from IPv4 to IPv6

The Transition Problem

We have a problem, and that is we are on IPv4 for most of our networks, and we want to be on IP version 6. So how do we make that transition? There's many ways that we can do that, to make that transition from one to the next and make it as smooth as possible.

Dual Stack

The first concept is this dual stack. Dual stack is very simplistic — really it just means we'll use both, for every interface that we have on this network. Let's say this is an internal network right here, and what we want is to use IPv6 on this internal network, but we also want to use IPv4. Well, that means that every device that is on this network can be dual stacked, which means it will have both an IP version 4 and a version 6 address, and therefore it can communicate either way to these different devices. Then if you have technologies that are better off using the IPv6, it can use that; or if you've got technologies that are better off using the IPv4, it can do that. You just need to make sure that all the devices on your network can talk both languages there.

Translation

Another thing that we can do is use translations on our networks in order to be able to facilitate using IPv6. So once again, let's say this is our local company right here that we're managing, and the outside world still is using IPv4, but internally we would like to use IPv6. So we are going to set up all of our devices here on this network and use IPv6. Then what will happen is that throughout this network all the communication will happen in IP version 6, but when it gets sent to the outside world, then we will be translating that to some sort of IPv4 address. And then vice versa: when it comes in, then it will be translating from IPv4 to an IPv6 address. So that's how we can do it. It's similar to a network address translation that we do where we have private addressing on our network and then it needs to be translated to a public address. So similar to that.

Now, what could happen actually for a lot of these companies is just the opposite. Rather than internally we have IPv4 — there's probably going to be a lot of our technologies that are still stuck on IPv4 and we're not switching — our ISP is requiring IPv6. So in a lot of our scenarios it's probably going to be exactly the opposite: the requirement is of the ISP to use IPv6, and so it translates from this IPv4 address to IPv6 as it's leaving the router. So that is also a very possible scenario that could be set up in your business.

This is a chart that I showed you before, and the chart shows us some different address ranges with IPv6. So we covered some of this, but I've added a few more here. I've added some of the addresses that get translated here, and we can see that these ranges right here are dedicated for that transition, and so we can do that address translation from one network to another. So just know that there's some specific ranges that are already set aside to do exactly that.

Tunneling

Then we have this concept of tunneling. Tunneling is how we get traffic from point A to point B when they have similar types of traffic, but across some networks that have different types of networks. Let me give you an example: a VPN tunnel. A VPN tunnel is, you have one network that you need to secure, then you need to connect it to another network that needs to be secure, and it needs to go across insecure networks. So we create a VPN tunnel, which encrypts the data and then transfers it over and then unencrypts the data to get it from point A to point B. So the idea behind tunneling is that we can get this traffic from point A to point B intact, the way it's supposed to be, but it's going to take a different form in between.

Here's an example of it. Let's say on this side of the network we have this all set up as IPv6, and then we have this side of the network that's set up also as IPv6, but everything in between has not made the transition yet. So what we need to do is take this traffic, this IP version 6 traffic, and send it across this link to this IPv6 traffic — so it needs to be IPv4 in between. We do this by encapsulating the IPv6 packets with IPv4 packets. So we take that IPv6, we add IPv4 headers to it, and then we send it across, and then it gets unpacked on the other side and then sent into this network on the other side. So that's tunneling, and how we get the information in there. Sometimes we see that, even though it's traversing this network right here, we view it as being a tunnel that goes from one location to the next, and that's where the things get tunneled across here.

Now, in this example right here, once again we probably would more likely see the reverse. What I mean by that is the IP version 4 would be on each side here, because we're going to have a lot of technologies that are still stuck on using the IPv4 that's on our computers, and it needs to be translated to IPv6 — or I shouldn't say translated, it needs to be tunneled across the IP version 6 — because this center equipment is probably more likely to be equipped with handling IPv6, and this is where we get a lot of the efficiencies of IPv6. So this would be also the scenario here, of IPv4 on each side, and we need to tunnel through the ip version networks right here.

Getting All the Way There

Slowly we can upgrade network to network, and the eventual goal is to get all of our networks set up this exact same way, so that everything is on IPv6 and we can move away from IPv4 and no longer operate it. Unfortunately, that's going to still be a little bit, because there's still a lot of technologies that rely on that IPv4 traffic. It will be a bit before we can make that full transition.