IPv6 from IPv4 is possible

IPv6 - Everything you need to know about switching to the new web standard

Michael Seemann

In Germany, all Internet access is gradually being converted to IPv6. We explain what changes with this Internet protocol for DSL, routers and home networks and what you have to pay attention to so that you can continue to be safe and fast in the network.

The Internet is running out of addresses: More and more devices require online access. You will also notice this in your home network - because where a few years ago you only used your PC or notebook to establish online access, your smartphone, tablet, NAS and television now also want to be provided with it. And then there is also the topic of Smart Home - or the “Internet of Things” (IoT). According to "Cybersecurity Trends 2018", around 500 IoT devices should be in service in every household by 2022. Juniper Research expects up to 50 billion connected IoT devices worldwide. And it is precisely this unbelievable number of clients who all want to access the Internet that is one of the most important reasons for the introduction of the IPv6 protocol (see also the box “Why IPv6 has to come now”).

For a long time you probably noticed little or nothing about this restructuring. Because the change of address on the Internet from the 4 version of the Internet Protocol (IPv4) to the successor version IPv6 has actually been dragging on for around a quarter of a century.

But now all providers in Germany are increasing their efforts and are gradually converting their connections to IPv6. The impact of this change of address on your Internet access depends on the method your provider uses to migrate to IPv6 and the way in which you use your Internet access at home. Therefore, we answer the most important questions that arise about IPv6 for online access and in the home network.

Finding out the IP address: It's that easy to find devices in your network

Has your internet connection already been converted to IPv6?

Your internet router can answer this question. Because in the Internet or connection settings of the modem router you will find the public IP address (sometimes there are two) with which your router is connected to the Internet and can be addressed from there. In the Fritzbox menu, for example, change to the “Internet -› Online Monitor ”directory. If you find a long IPv6 address there (see box "This is how an IPv6 address is made up") that begins with "2001", your connection has already been switched to IPv6.

Can you access IPv6 web pages with an IPv4 connection?

EnlargeIf you use IPv6, you will see this in the menu of your modem router.

In Germany, fewer and fewer Internet connections still use IPv4 only: Older ADSL connections, which are still to be converted to VDSL, are often connected with a pure IPv4 address. These connections can be recognized by the fact that only a public IPv4 address is entered in the Internet (or connection) settings of your modem router - but no IPv6 address, not even in addition to the IPv4 address.

So that a connection to the other IPv6 network is also possible from these pure IPv4 connections, a so-called 6to4 tunnel is used. The router packs the IPv6 data packets to be sent into an IPv4 packet. In this way, IPv6 packets can also be sent or "tunneled" over the IPv4 network. The prerequisite for this is that your router supports IPv6 and the 6to4 tunnel, which is the case with all reasonably up-to-date network devices. If your router cannot do this and this function cannot be activated either, you should point this out to your provider: The chances are then good that you will get a current router with IPv6 support.

To activate the 6to4 tunnel in a Fritzbox, go to “Internet -› Access data - ›IPv6” in the extended web menu and check “IPv6 support active” there. Now select the option "Use IPv6 connection with tunnel protocol" and then select the tunnel protocol "6to4". No further settings are required. Now scroll all the way down and click "Apply" to save the changes. You should then be able to access pages on the Internet from your home network that can only be accessed via IPv6. Please note the following: This 6to4 setting only makes sense if you are only connected to the Internet via a public IPv4 address.

Tips and tools for IPv6

With Windows on-board tools and special network tools, you can find out immediately whether your home network can handle IPv6.

IPv6 check: To quickly check whether you can go online using IPv6 from your home network, simply go to an IPv6 website, such as: ipv6.google.com

IPv6 address: Since Windows Vista, IPv6 has been integrated into Windows and activated automatically. Open the command prompt with Win-R and "cmd". The command "ipconfig" lists the IPv6 and IPv4 addresses of all network adapters on the Windows PC. Please note: The so-called “connection-local IPv6 address” beginning with “fe80” is only used for communication between devices in the same LAN: the router does not forward data packets with this address to the Internet.

EnlargeSoftperfect Network Scanner also shows you the IPv6 addresses of your devices in the home network.

IPv6 ping: You can also ping a website via IPv6 in the command prompt and check whether it can also be reached via IPv6. The command is “ping -6 website”, for example “ping -6 pcwelt.de”.

Softperfect Network Scanner 7.1.6: The tool scans the local network and, in addition to the IPv4 addresses, also displays the IPv6 addresses of IPv6-compatible hosts. To do this, you just need to check the box in front of “Resolve IPv6 addresses” under “Options -› Program Options - ›Additional” in the tool menu. You can download the Network Scanner.

What are the different types of IPv6 connections?

EnlargeThis example shows a Fritzbox that has only received a public IPv4 address from the provider.

Two different variants of IPv6 connections are used in Germany, on the one hand as "Dual Stack", on the other hand as "DS-Lite" (Dual Stack Lite). You can access all IPv6 and all IPv4 websites and services from your home network without any problems using both connection variants - usually via the IPv6 router of your network operator. In principle, this also applies to all major streaming providers. If problems arise here, this is usually not due to the IPv6 or IPv4 protocols, but to incorrectly programmed client apps.

The other way around, however, these connection types can cause problems - namely when you want to access individual devices in your home network via remote access from the Internet. The same applies if you have set up a VPN connection to the home network.

IP telephone connection - these are the advantages and disadvantages

What is a “dual stack” connection for IPv6?

EnlargeIf your router is connected via IPv4, it can still reach IPv6 Internet sites.

"Dual Stack" is a combined IPv4 / IPv6 Internet connection that fully supports both Internet protocols. The term “dual stack” stands for the two (“dual”) versions of the Internet protocol (“protocol stack”). With a “dual stack” connection, you receive two public Internet addresses from your provider: one IPv4 and one IPv6 address. Your router can now receive any incoming and outgoing connections via IPv6 or IPv4 and forward them to the web as required.

Dual stack thus offers a very comfortable transition from IPv4 to IPv6, which the ambitious home network user in particular appreciates. External access to certain home network devices such as NAS or IP cameras or VPN connections can continue to be used in the usual way via IPv4.

However, the dual-stack operation does not mean that the provider spares himself the assignment of one of the hardly available IPv4 addresses: For this reason, it is only offered by the vast majority of providers on request or at an additional cost, for example for a business connection. The only provider in Germany that can still switch dual stacks as standard is Telekom: The former monopoly provider still has a sufficiently large pool of IPv4 addresses.

Why IPv6 has to come now

The big disadvantage of IPv4 is the relatively small number of unique addresses in order to be able to communicate directly with individual devices on the Internet. Because an IPv4 address is limited to 32 bits (4 bytes), with which exactly 232 or almost 4.3 billion devices on the Internet can be uniquely addressed - and that is now far too little.

With IPv6, on the other hand, Internet addresses with a length of 128 bits can be formed, which corresponds to an elusive number of 2128 or 3.4 x 1038 unique address combinations. Written out would be a 34 with 37 zeros. With IPv6, a sufficient number of IP addresses are available in the long term, even if every grain of sand on earth has its own IP address. However, with IPv6 the notation of an IP address also changes (see the box "This is how an IPv6 address is composed").

In the meantime, many online services are already two-pronged: their websites and offers can be accessed via both IPv4 and IPv6 addresses on the Internet. This is the only way to ensure that really every client can access the operator's online offer.

What is a "DS-Lite" connection and which providers offer it?