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Subnet router failover

When using subnet routers in large networks, you may want to provide a failover subnet router (also called a high-availability subnet router) to ensure users of your network can continue to access resources if one routing device goes offline.

This feature is only available for the Business plan or higher.

Step 1: Set up multiple subnet routers

Follow our guide to configure subnet routers, exposing the same routes on the same network on 2+ devices. For example, to expose 10.0.0.0/24,10.1.0.0/24, you’ll want to run a command like this on 2+ devices.

sudo tailscale up --advertise-routes=10.0.0.0/24,10.1.0.0/24

You can configure as many subnet routers as you want to act as a failover.

Step 2: Activate the subnet routers in the admin panel

Visit the admin panel, navigate to the machines page, locate your subnet router and using the ellipsis icon icon at the end of the table, select “Review subnet routes…” This will open up the Subnet settings.

Click “Enable” on your routes so that Tailscale distributes the subnet routes to the rest of the nodes on your Tailscale network.

You may want to disable key expiry on your server to avoid having to periodically reauthenticate. See key expiry for more information about machine keys and how to disable their expiry.

Step 3: Done!

Once you have 2+ subnet routers exposing the same route on the same network, the Tailscale control server will automatically manage the failover between the different routers.

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