Mobiles and tablets and IPv6

Does anyone know if mobile phones/tablets are steered more towards IPv6, than IPv4 and if so, is there a way to manually configure IPv6 on these devices?

Edited by dwg1 (Mon 04-Feb-19 02:35:16)

My iPhone uses IPv6 by default when on an IPV6 capable network, falling back to IPv4 when it needs to.

It doesn't appear to allow manual configuration of IPv6 though.

My phone and tablet (both Android) support IPv6 via SLAAC only. There's no option to configure static. If there is IPv6 available it will use that by default.

Look up the term "Happy Eyeballs" (yes really)

Preference will depend more on operating system / version than hardware or applications (in general).

If the installed OS isn't using Happy Eyeballs you can assume it will prefer IPv6 when both available, but the preference can also be influenced by whether the source and target address are on the (same) LAN and whether the received IPv6 address is native or tunnelled over IPv4.

Attempting to manually configure IPv6 is discouraged, partly because there is more likelyhood for getting things wrong, and partly because interfaces tend to have multiple addresses, such as both a global and a link-local address, so it's more effective to manage it at the network (prefix) level than the device level.
If manually addressing it's alot of extra work to also add the routes and DNS settings on each device and more so if you need to renumber a network.

The router and optionally the DHCP server for the network (which may be the same or different) should be able to manage the IPv6 assignments.
If your existing / ISP-issued router doesn't give you enough control over addressing there are other choices.

The ideal case is to have your devices listed in your LAN DNS server with v4 and v6 addresses such that you only need refer to them by DNS name and the IP addresses become an abstraction.

An exception to the general rule would be something like an Active Directory Domain Controller wanting to have a fixed address because of the role it plays in authentication and authorisation. Whereas for something like a printer or even a NAS I wouldn't bother and use DHCP reservations instead much as we can per IPv4.

If you do want to configure IPv6 addresses manually test with ULA addressing - e.g. you can use an RFC 4193 subnet generator
and check 2 or 3 items can communicate on the generated subnet.
more commentary on the Infoblox blog

Edited by prlzx (Mon 04-Feb-19 22:24:40)

It will depend on the mobile network serving their SIM. That will choose the default. I don't think you would be able to choose IPv6 if the network is running on IPv4.

If you can find and alter the APN/Profile in the device's settings you might be able to switch the field APN Protocol between IPv4/IPv6 or IPv4 only or IPv6 only, when the network is running on IPv6.

There have been issues on a certain mobile network where when it switched from using IPv4 to IPv6 certain connectivity issues appeared, often when the device itself is interacting with another device, like signal boosters & games consoles. These issues were often overcome by forcing the APN Protocol to IPv4 only.

My experience of this is purely empirical & I don't understand the theory underlying it.

Thank you all for your quality input My query is more geared towards wifi rather than data. Would I be right in thinking there are very few UK ISPs who have their own IPv6 DNS servers? Could it also be possible that some apps are geared more towards IPv6 than IPv4?

5 years ago it was a minority of ISPs (in terms of customer numbers) notably AAISP IDNet and who had deployed IPv6, but if BT and Sky have done a rollout, I guess that's no longer the case. I can't speak for Talk Talk or Virgin Media but they would another big chunk.

Any ISP who offers true dual stack IPv4 plus IPv6 will have deployed DNS servers within their network as they have always done with IPv4, can even be same box(es).

Note that as a rule, devices on your home LAN receive DNS settings from your router pointing them at its own LAN interface address. It's your home router which receives DNS settings from the ISP on its WAN interface.

There are a couple of ways the router can implement this. It can either just forward all non-local requests to the ISP for resolving, or it can have a small cache to store the most recent / frequent results. A cache is the norm unless the router itself is very low powered.

Yes both my posts are in regards to portable devices (well anything with an IP stack really) connecting to your home network -

- rather than mobile 3G/4G. In that case presence of IPv6 depends on the mobile operator and service they have in your area. Mobile networks can hand out private or public IPs to devices so even on IPv4 I sometimes get an RFC1918 when travelling but mostly a true public one. I haven't seen an IPv6 address on my 4G yet but if anything it's a better fit for that sheer number of end user devices.

Edited by prlzx (Tue 05-Feb-19 20:40:51)

In reply to a post by JonRennie:

My iPhone uses IPv6 by default when on an IPV6 capable network, falling back to IPv4 when it needs to.

It doesn't appear to allow manual configuration of IPv6 though.

I have the same with my OnePlus 5.

I have owned a few Android mobiles and one tablet. I have yet to find the ability to manually input the IPv6 configuration for them. It is my belief that some of them are geared to prioritise IPv6 over IPv4, which can cause issues. In my opinion it would be useful if the ability to manually input IPv6 configurations were added to the Android OS. I know some have mentioned about changing settings causing issues, but these settings would almost certainly be placed in the advanced settings, which by default someone would normallly have to search for..