Skip to main content
Wake Forest University

Transferring data between Mac computers using a Thunderbolt bridge

Modified on: Fri, Sep 11, 2026 3:38 PM

Utilize a Thunderbolt network bridge between two Mac computers to achieve the fastest possible data transfer speeds. This method bypasses standard Wi-Fi or Ethernet limitations and optimizes network protocols for large-scale data transfers between two Mac computers.


Prerequisites:

  • Source Mac (the computer with the data)

  • Destination Mac (the computer receiving the data)

  • A certified Thunderbolt 4 or Thunderbolt 5 cable (Standard USB-C charging cables will not provide sufficient bandwidth).

 Phase 1: Pre-Transfer Preparation (Crucial for Maximum Speed) 

Note: Before connecting the computers, preparing your data on the Source Mac is essential for preventing bottlenecks and errors.

  • Manage Cloud Syncing Software If you use cloud storage services (iCloud Drive, Dropbox, OneDrive, or Google Drive for Desktop), you must pause syncing or quit these applications before transferring.

    • Why this matters: Cloud services often use "placeholder" or "online-only" files to save local disk space. If you attempt to copy these placeholders over the network, macOS will attempt to download the full file from the internet on the fly. This will severely throttle your transfer speed and frequently cause the transfer to time out or fail.

  • Compress Large Directories into Archives For folders containing thousands of small files (such as Documents, Photos library, and Music), right-click the folder and select "Compress [Folder Name]" to create a single .zip archive.

    • Why this matters: The SMB network protocol handles a single 50GB .zip file significantly faster than it handles 10,000 individual 5MB files. Zipping files forces the Mac's internal SSDs and the network interface to utilize sequential read/write speeds rather than random read/write speeds, drastically reducing network overhead. You will unpack these archives on the destination Mac once the transfer is complete.

    • Note: Compressing data can take some time, additionally it will take extra space on your Source Mac. Be mindful that you only need to target directories with many small files.  When transferring the data, select those compressed folders, and not the uncompressed data.  For example, if you compressed "Documents" you would transfer the "Documents.zip" in later steps, but not the original "Documents" folder.

 Phase 2: Physical Connection & Network Configuration 
  • Connect the Macs Plug the Thunderbolt 4 or 5 cable directly into a Thunderbolt port on both the Source Mac and the Destination Mac.
  • Configure Thunderbolt Settings (Source Mac)

    1. Open System Settings > Network.

    2. Look for the Thunderbolt Bridge connection (it should show a green indicator). Click on it.

    3. Make a note of the IP Address listed here (e.g., 169.254.x.x or a similar self-assigned IP). You will need this later.

    4. Click Details... > Hardware.

    5. Change the Configure dropdown to Manually.

    6. Change the MTU setting to Custom and enter 9000 (This enables Jumbo Frames).

    7. Click OK.

    • Note: Enabling Jumbo Frames allows the computers to send much larger packets of data at once, reducing the CPU overhead required to process network traffic and maximizing the Thunderbolt cable's bandwidth.

  • Configure Thunderbolt Settings (Destination Mac)

    1. Open System Settings > Network.

    2. Click on the Thunderbolt Bridge connection.

    3. Just like on the Source Mac, click Details... > Hardware.

    4. Change the Configure dropdown to Manually.

    5. Change the MTU setting to Custom and enter 9000. Click OK. (Both computers must have Jumbo Frames enabled for this to work properly).

 Phase 3: Enable File Sharing 
  • Turn on File Sharing (Source Mac)

    1. Open System Settings > General > Sharing.

    2. Toggle the switch next to File Sharing to the ON position.

    3. Click the "i" (info) icon next to File Sharing.

    4. Ensure the folders you want to share (or your entire user folder) are listed in the "Shared Folders" box.

    5. Under "Users," ensure your specific user account is listed and has Read & Write privileges. Click Done.

 Phase 4: Connect and Transfer 
  • Mount the Source Mac as a Server (Destination Mac)

    1. On the Destination Mac, click anywhere on the desktop to ensure Finder is active.

    2. In the top menu bar, click Go > Connect to Server (or press Command + K).

    3. In the Server Address field, type: smb://[IP_Address_of_Source_Mac] (Replace the bracketed text with the IP address you wrote down in Phase 2, Step 2).

    4. Click Connect.

  • Authenticate

    1. A prompt will appear asking for a name and password.

    2. Important: You must authenticate using the Username and Password of the account on the Source Mac (the computer you are connecting to), not the Mac you are currently using.

    3. Select the volumes or user folders you wish to mount. They will appear on your desktop or in the Finder sidebar under "Locations."

  • Execute the Transfer

    1. Open the mounted Source Mac drive in Finder.

    2. Drag and drop the .zip archives and any other large files you prepared onto the Destination Mac’s local internal drive.

    3. Because you are using a Thunderbolt Bridge with Jumbo Frames and compressed archives, you should see transfer speeds dramatically exceeding standard Gigabit network speeds.

 Phase 5: Post-Transfer Clean Up 

Once the transfer is completely finished:

  • Double-click the transferred .zip archives on the Destination Mac to uncompress them into their normal folder structures.

  • Eject the Source Mac network drive from the Destination Mac.

  • Turn off File Sharing on the Source Mac if it is no longer needed.

  • Re-enable, sign into, or un-pause iCloud, Dropbox, OneDrive, or Google Drive on both machines as necessary.

Was this answer helpful? Yes No

Sorry we couldn't be helpful. Help us improve this article with your feedback.