I'm considering purchasing a new iMac and recently learned that Thunderbolt 3 can be used to create a Thunderbolt network bridge between two Macs. I assume that connection over Thunderbolt will be many times faster than an ethernet connection.

I also want both iMac's to be connected to my LAN via their ethernet adapters. Is it possible for both of these connections to run independently, simultaneously, so that each Mac can still "talk" to the internet and other devices on the LAN, but "talk" to each other at Thunderbolt speeds?

  • Are you planning on large file transfers between the a Macs? If not, you’re not going to see a benefit. It’s like having a 10 lane highway for two motorcycles.
    – Allan
    Feb 18, 2020 at 0:52
  • 1
    Yes. I have 10 motorcycles :P. Not only large files, but also thousands of very small files, frequently, and I intend on running numerous bandwidth heavy applications that hopefully can talk to each other between the two machines. The 1Gbps ethernet already maxes out, and I'm hoping that a thunderbolt bridge will be used when the two machines "talk" instead of the LAN. I'm guessing that macOS will just automatically favor the bridge over the ethernet? Feb 18, 2020 at 2:11
  • It won’t favor just based on speed. It looks for the lowest “cost” like number of hops, latency, etc. Besides, you shouldn’t have the same IP addressing scheme for the TB connection as the LAN. This way you can control the traffic of what goes where.
    – Allan
    Feb 18, 2020 at 4:46

1 Answer 1


Yes, that is definitely possible - indeed this is what happens if you hook them up like this.

Thunderbolt 3 enables transfer rates up to a theoretically high of 40 Gbps.

The relative speed depends on the type of Ethernet connection you're comparing it with. If you're using 10-gigabit ethernet - then you're probably not going to see any practical benefit from the Thunderbolt 3 connection (if you're not transferring stuff from disk, you might get huge benefits though). If you're using gigabit or slow ethernet, you're going to see a massive improvement in transfer speeds.


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