General Information About Anycast Routing
Anycast routing means that traffic from you to our race servers will travel as short a distance as possible on the open internet before reaching our internet provider’s backbone to finish its path to our race servers. The return traffic to you will follow the same path back to you, meaning it will avoid the open internet as long as possible.
More typical unicast routing means that traffic from you to our race servers may hop between many different providers until it gets close to the destination race server and arrives on network infrastructure we control. It can be a lot less reliable depending on the providers that exist between you and the iRacing race servers you’re trying to connect to.
This can be confusing when you use tools like ping, PingPlotter, or traceroute to test our servers, because it will always appear that the server is only a few milliseconds away from you, even if it’s halfway around the world. That’s because the test traffic from your machine will appear to stop once it reaches our provider’s infrastructure, even when the server you’re trying to reach is still around the world from there. Please see our Gathering Ping / Trace Data for Troubleshooting page for information about using iRacingPing.exe for more accurate data.
Anycast Routing Configuration for iRacing
All race farms support both unicast and anycast routing. By default, your system will reach our race servers via anycast routing unless there appears to be a problem.
You can tell iRacing not to use anycast routing for your connections to race servers by opening the iRacingUI (or iRacing Web), clicking the Settings icon at the bottom right, click the Network tab and moving the "Prefer Anycast” switch to off.
For most customers, there will be little difference between connecting with anycast (the default) and unicast routing. If anycast routing is slower than unicast for some reason, it is still preferred for more connection stability. If anycast routing is so much slower than unicast routing that the latency will impact performance, your machine should fall back to unicast routing automatically when you join a race.
In the iRacing UI, you can see your unicast and anycast ping times for each farm when you click the "connections" icon on the top bar and hover your mouse cursor over the bar graphs next to each farm/protocol. Look at the "Average Ping" value.
If you find that unicast is better for some of our server farms, but anycast is better for others, there is a way you can handle this. First, make sure you leave the “ Anycast” option described above enabled (the default). Then, in Windows File Explorer, in your Documents\iRacing directory, you can (while the simulation is not running) edit a file named "app.ini". You can double-click on this file, and edit it using Notepad. Add the "excludeAnycastOnFarms=" setting to the [Misc] section.
[Misc]
excludeAnycastOnFarms= ; Comma-separated list of 0 or more of farms to not race using anycast routing: (apne1,apse2,euc1,sae1,use2,usw1)
On the right side of the =, list the farms you do NOT want to use anycast routing. For example, if you find that your ping times or packet loss to our US-east and Sydney farms are worse with anycast than unicast, but anycast is performing well on our other farms, you could use `excludeAnycastOnFarms=use2,apse2`.
[Misc]
excludeAnycastOnFarms=euc1,use2 ; Comma-separated list of 0 or more of farms to not race using anycast routing: (apne1,apse2,euc1,sae1,use2,usw1)
As of 2025/08/04, race farm prefixes are:
euc1 for our farm in Frankfurt
use2 for our US-east farm
usw1 for our US-west farm
sae1 for Sao Paulo
apne1 for Tokyo
apse2 for Sydney