Thunderbolt Bridge

~12 min · thunderbolt, bridge, p2p, static-ip

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The fastest LAN you'll ever build

Connect two Macs with a Thunderbolt cable and macOS automatically presents a Thunderbolt Bridge network interface on both. Throughput is staggering — iperf3 typically reports 20–30 Gbps, with real-world file transfers at 2–3 GB/s (disk-limited, not network-limited).

Setup is two commands

The Thunderbolt Bridge appears in System Settings → Network the moment you connect the cable. By default, link-local addressing (169.254.x.x) auto-configures. For predictable use, set static IPs manually — the cable is point-to-point, so a /30 with two usable addresses is plenty.

Code

Static IPs on both ends·bash

# On Mac A
sudo networksetup -setmanual "Thunderbolt Bridge" 10.10.10.1 255.255.255.252

# On Mac B
sudo networksetup -setmanual "Thunderbolt Bridge" 10.10.10.2 255.255.255.252

# Verify
ifconfig | grep -A 2 'Thunderbolt'

# Test
ping 10.10.10.2   # from Mac A
ping 10.10.10.1   # from Mac B

# Throughput test
iperf3 -s         # on Mac A
iperf3 -c 10.10.10.1 -P 4   # on Mac B
# Expect 20-30 Gbps

Add it to ~/.ssh/config·ssh-config

Host office.tb
    HostName 10.10.10.1
    User you_username

Host server.tb
    HostName 10.10.10.2
    User you_username

External links

Apple Thunderbolt cables

Exercise

If you have two Macs with Thunderbolt ports and a TB3/TB4 cable, connect them. Set static IPs as above. Test ping. Run iperf3 across the bridge — note the staggering speed. Add .tb aliases in ~/.ssh/config so you can ssh office.tb for the fastest path between two specific Macs (great for migrations or ad-hoc fast transfers).