All race farms now support both IPv4 and IPv6.

On the classic member site, you can tell iRacing to use IPv6 for your connections to race servers by using the Settings link on the central navigation bar, and then moving the IPv6 switch to on.  From the iRacing UI, you can open the Settings using the gear icon near the top right, and move the IPv6 switch to on.  If that switch won't respond, or just keeps moving back to off, then you do not have IPv6.  You can check if you have IPv6 by clicking here:

For most customers, there will be little noticeable difference between running with IPv6 vs. IPv4 (default).  However, for some, the IPv6 routing from their ISPs is significantly worse than IPv4 and for others it will be significantly better.

You can see your IPv4 and IPv6 ping times while on the classic member web site by hovering your mouse cursor over the "Ping" note in at the top of the site. In the iRacing UI, you can click on the "connections" icon on the top bar, and then hover your mouse cursor over the bar graphs next to each farm/protocol. Look at the "Average Ping" value.

If you should find that IPv6 is better to some of our server farms, but IPv4 is better to others, there is a way you can handle this.  You can enable the simulation to use IPv6 as described above.  Then, in your My Documents\iRacing directory, you can (while the simulation is not running), edit a file named "app.ini".  You can just double click on this file, and edit it using Notepad.  Add the "excludeIPv6OnFarms=" setting to the [Misc] section.

excludeIPv6OnFarms=                       ; Comma-separated list of 0 or more of farms to not race using IPv6: (bosrace,sydrace,amstrace)

On the right side of the =, list the farms that you do NOT want to use IPv6.  For example, if you find that your ping times to our Amsterdam and Boston farms are better with IPv4, but are better to Sydney with IPv6, you can tell us to not use IPv6 to our Amsterdam or Boston farms, like this:

excludeIPv6OnFarms=amstrace,bosrace                ; Comma-separated list of 0 or more of farms to not race using IPv6: (bosrace,sydrace,amstrace)

You can also shorten those entries down to just "ams", "bos", and "syd".

As of 2019/07/30

In the "IPv6 is worse than IPv4" camp, there are:

  • Charter cable subscribers in the US northeast have worse ping times to our Boston race farm than IPv4.
  • A fair number of users in Australia have higher pings to our Boston farm than they do with IPv4, but that will most likely be resolved with our new AU/NZ circuit.
  • A fair number of users in Brazil have worse IPv6 ping times to our Boston farm. Some ISP there is routing IPv6 only through China Mobile, with traffic going to the US west coast, instead of to Miami.

In the IPv6 will be better than IPv4 camp:

  • Some iRacing customers are using ISPs that have something called "Carrier Grade NAT" (CGN), and some of those ISPs seem to have poorly implemented this technology. We sometimes see cases where a customer's ISP changes their IPv4 address out from under them in the middle of a race. This causes a disconnection from the race. We have mostly seen this from small ISPs here in the US, but originally started seeing this behavior from ISPs in Germany. For these users, you definitely should switch to IPv6!