Skip to content

Instantly share code, notes, and snippets.

@scyto
Last active August 23, 2025 17:56
Show Gist options
  • Save scyto/67fdc9a517faefa68f730f82d7fa3570 to your computer and use it in GitHub Desktop.
Save scyto/67fdc9a517faefa68f730f82d7fa3570 to your computer and use it in GitHub Desktop.
Thunderbolt Networking Setup

Thunderbolt Networking

this gist is part of this series

you wil need proxmox kernel 6.2.16-14-pve or higher.

Load Kernel Modules

  • add thunderbolt and thunderbolt-net kernel modules (this must be done all nodes - yes i know it can sometimes work withoutm but the thuderbolt-net one has interesting behaviou' so do as i say - add both ;-)
    1. nano /etc/modules add modules at bottom of file, one on each line
    2. save using x then y then enter

Prepare /etc/network/interfaces

doing this means we don't have to give each thunderbolt a manual IPv6 addrees and that these addresses stay constant no matter what Add the following to each node using nano /etc/network/interfaces

If you see any sections called thunderbolt0 or thunderbol1 delete them at this point.

Create entries to prepopulate gui with reminder

Doing this means we don't have to give each thunderbolt a manual IPv6 or IPv4 addrees and that these addresses stay constant no matter what.

Add the following to each node using nano /etc/network/interfaces this to remind you not to edit en05 and en06 in the GUI

This fragment should go between the existing auto lo section and adapater sections.

iface en05 inet manual
#do not edit it GUI

iface en06 inet manual
#do not edit in GUI

If you see any thunderbol sections delete them from the file before you save it.

*DO NOT DELETE the source /etc/network/interfaces.d/* this will always exist on the latest versions and should be the last or next to last line in /interfaces file

Rename Thunderbolt Connections

This is needed as proxmox doesn't recognize the thunderbolt interface name. There are various methods to do this. This method was selected after trial and error because:

  • the thunderboltX naming is not fixed to a port (it seems to be based on sequence you plug the cables in)
  • the MAC address of the interfaces changes with most cable insertion and removale events
  1. use udevadm monitor command to find your device IDs when you insert and remove each TB4 cable. Yes you can use other ways to do this, i recommend this one as it is great way to understand what udev does - the command proved more useful to me than the syslog or lspci command for troublehsooting thunderbolt issues and behavious. In my case my two pci paths are 0000:00:0d.2and 0000:00:0d.3 if you bought the same hardware this will be the same on all 3 units. Don't assume your PCI device paths will be the same as mine.

  2. create a link file using nano /etc/systemd/network/00-thunderbolt0.link and enter the following content:

[Match]
Path=pci-0000:00:0d.2
Driver=thunderbolt-net
[Link]
MACAddressPolicy=none
Name=en05
  1. create a second link file using nano /etc/systemd/network/00-thunderbolt1.link and enter the following content:
[Match]
Path=pci-0000:00:0d.3
Driver=thunderbolt-net
[Link]
MACAddressPolicy=none
Name=en06

Set Interfaces to UP on reboots and cable insertions

This section en sure that the interfaces will be brought up at boot or cable insertion with whatever settings are in /etc/network/interfaces - this shouldn't need to be done, it seems like a bug in the way thunderbolt networking is handled (i assume this is debian wide but haven't checked).

Huge thanks to @corvy for figuring out a script that should make this much much more reliable for most

  1. create a udev rule to detect for cable insertion using nano /etc/udev/rules.d/10-tb-en.rules with the following content:
ACTION=="move", SUBSYSTEM=="net", KERNEL=="en05", RUN+="/usr/local/bin/pve-en05.sh"
ACTION=="move", SUBSYSTEM=="net", KERNEL=="en06", RUN+="/usr/local/bin/pve-en06.sh"
  1. save the file

  2. create the first script referenced above using nano /usr/local/bin/pve-en05.sh and with the follwing content:

#!/bin/bash

LOGFILE="/tmp/udev-debug.log"
VERBOSE="" # Set this to "-v" for verbose logging
IF="en05"

echo "$(date): pve-$IF.sh triggered by udev" >> "$LOGFILE"

# If multiple interfaces go up at the same time, 
# retry 10 times and break the retry when successful
for i in {1..10}; do
    echo "$(date): Attempt $i to bring up $IF" >> "$LOGFILE"
    /usr/sbin/ifup $VERBOSE $IF >> "$LOGFILE" 2>&1 && {
        echo "$(date): Successfully brought up $IF on attempt $i" >> "$LOGFILE"
        break
    }
  
    echo "$(date): Attempt $i failed, retrying in 3 seconds..." >> "$LOGFILE"
    sleep 3
done

save the file and then

  1. create the second script referenced above using nano /usr/local/bin/pve-en06.sh and with the follwing content:
#!/bin/bash

LOGFILE="/tmp/udev-debug.log"
VERBOSE="" # Set this to "-v" for verbose logging
IF="en06"

echo "$(date): pve-$IF.sh triggered by udev" >> "$LOGFILE"

# If multiple interfaces go up at the same time, 
# retry 10 times and break the retry when successful
for i in {1..10}; do
    echo "$(date): Attempt $i to bring up $IF" >> "$LOGFILE"
    /usr/sbin/ifup $VERBOSE $IF >> "$LOGFILE" 2>&1 && {
        echo "$(date): Successfully brought up $IF on attempt $i" >> "$LOGFILE"
        break
    }
  
    echo "$(date): Attempt $i failed, retrying in 3 seconds..." >> "$LOGFILE"
    sleep 3
done

and save the file

  1. make both scripts executable with chmod +x /usr/local/bin/*.sh
  2. run update-initramfs -u -k all to propogate the new link files into initramfs
  3. Reboot (restarting networking, init 1 and init 3 are not good enough, so reboot)

Enabling IP Connectivity

proceed to the next gist

Slow Thunderbolt Performance? Too Many Retries? No traffic? Try this!

verify neighbors can see each other (connectivity troubleshooting)

##3 Install LLDP - this is great to see what nodes can see which.

  • install lldpctl with apt install lldpd on all 3 nodes
  • execute lldpctl you should info

make sure iommu is enabled (speed troubleshooting)

if you are having speed issues make sure the following is set on the kernel command line in /etc/default/grub file intel_iommu=on iommu=pt one set be sure to run update-grub and reboot

everyones grub command line is different this is mine because i also have i915 virtualization, if you get this wrong you can break your machine, if you are not doing that you don't need the i915 entries you see below

GRUB_CMDLINE_LINUX_DEFAULT="quiet intel_iommu=on iommu=pt" (note if you have more things in your cmd line DO NOT REMOVE them, just add the two intel ones, doesnt matter where.

Pinning the Thunderbolt Driver (speed and retries troubleshooting)

identify you P and E cores by running the following

cat /sys/devices/cpu_core/cpus && cat /sys/devices/cpu_atom/cpus

you should get two lines on an intel system with P and E cores. first line should be your P cores second line should be your E cores

for example on mine:

root@pve1:/etc/pve# cat /sys/devices/cpu_core/cpus && cat /sys/devices/cpu_atom/cpus
0-7
8-15

create a script to apply affinity settings everytime a thunderbolt interface comes up

  1. make a file at /etc/network/if-up.d/thunderbolt-affinity
  2. add the following to it - make sure to replace echo X-Y with whatever the report told you were your performance cores - e.g. echo 0-7
#!/bin/bash

# Check if the interface is either en05 or en06
if [ "$IFACE" = "en05" ] || [ "$IFACE" = "en06" ]; then
# Set Thunderbot affinity to Pcores
    grep thunderbolt /proc/interrupts | cut -d ":" -f1 | xargs -I {} sh -c 'echo X-Y | tee "/proc/irq/{}/smp_affinity_list"'
fi
  1. save the file - done

Extra Debugging for Thunderbolt

dynamic kernel tracing - adds more info to dmesg, doesn't overhwelm dmesg

I have only tried this on 6.8 kernels, so YMMV If you want more TB messages in dmesg to see why connection might be failing here is how to turn on dynamic tracing

For bootime you will need to add it to the kernel command line by adding thunderbolt.dyndbg=+p to your /etc/default/grub file, running update-grub and rebooting.

To expand the example above"

`GRUB_CMDLINE_LINUX_DEFAULT="quiet intel_iommu=on iommu=pt thunderbolt.dyndbg=+p"`  

Don't forget to run update-grub after saving the change to the grub file.

For runtime debug you can run the following command (it will revert on next boot) so this cant be used to cpature what happens at boot time.

`echo -n 'module thunderbolt =p' > /sys/kernel/debug/dynamic_debug/control`

install tbtools

these tools can be used to inspect your thundebolt system, note they rely on rust to be installedm you must use the rustup script below and not intsall rust by package manager at this time (9/15/24)

apt install pkg-config libudev-dev git curl
curl https://sh.rustup.rs -sSf | sh
git clone https://github.com/intel/tbtools
restart you ssh session
cd tbtools
cargo install --path .
@DamianRyse
Copy link

I'm getting crazy high retries on iperf3 regardless of what I tried:

* Set smp_affinity

* cpupower to performance

* Disabled c-states and ASPM

* Tried 3 different thunderbolt cables (OWC, CableMatters, Club3D)

I'm using 3x MS-01, any idea what else to try?

Did you also force the pci speed to gen4?

Yep, no difference

Did you make sure for the affinity script it is executable? You may see earlier that was my issue for one of my ms-01 meshes.

Yep I did. smp_affinity_list look all correct too.

@DamianRyse is that just with turbo boost on in bios?

Hi @DomMintago
Yes, it must be enabled in the UEFI. It can also be enabled/disabled on Linux itself by checking the value of /sys/devices/system/cpu/intel_pstate/no_turbo
0 -> Turbo Mode is enabled
1 -> Turbo Mode is disabled

When Turbo Mode is disabled, it absolutely helps to limit the max througput of your Thunderbolt interfaces to get a stable data transfer rate: (replace "en06" with your interface name)

tc qdisc add dev en06 root tbf rate 10gbit burst 32m latency 400ms

For me, 10gbit was the sweet spot for low to none retries and a almost constant transfer rate of 10 Gbps.

To delete the limit:

tc qdisc del dev en06 root

iperf3 test with Turbo Mode disabled and throughput limited to 10gbit

Connecting to host 10.0.0.2, port 5201
[  5] local 10.0.0.1 port 40840 connected to 10.0.0.2 port 5201
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-1.00   sec  1.19 GBytes  10.3 Gbits/sec   35   2.26 MBytes
[  5]   1.00-2.00   sec  1.16 GBytes  9.98 Gbits/sec    3   2.26 MBytes
[  5]   2.00-3.00   sec  1.16 GBytes  10.0 Gbits/sec    4   2.26 MBytes
[  5]   3.00-4.00   sec  1.16 GBytes  9.98 Gbits/sec    0   2.26 MBytes
[  5]   4.00-5.00   sec  1.16 GBytes  9.99 Gbits/sec    0   2.26 MBytes
[  5]   5.00-6.00   sec  1.16 GBytes  9.99 Gbits/sec    0   2.26 MBytes
[  5]   6.00-7.00   sec  1.16 GBytes  9.99 Gbits/sec    0   2.26 MBytes
[  5]   7.00-8.00   sec  1.16 GBytes  10.0 Gbits/sec    0   2.26 MBytes
[  5]   8.00-9.00   sec  1.16 GBytes  9.99 Gbits/sec    0   2.26 MBytes
[  5]   9.00-10.00  sec  1.16 GBytes  9.98 Gbits/sec    0   2.26 MBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  11.7 GBytes  10.0 Gbits/sec   42            sender
[  5]   0.00-10.00  sec  11.7 GBytes  10.0 Gbits/sec                  receiver

@DomMintago
Copy link

I'm getting crazy high retries on iperf3 regardless of what I tried:

* Set smp_affinity

* cpupower to performance

* Disabled c-states and ASPM

* Tried 3 different thunderbolt cables (OWC, CableMatters, Club3D)

I'm using 3x MS-01, any idea what else to try?

Did you also force the pci speed to gen4?

Yep, no difference

Did you make sure for the affinity script it is executable? You may see earlier that was my issue for one of my ms-01 meshes.

Yep I did. smp_affinity_list look all correct too.
@DamianRyse is that just with turbo boost on in bios?

Hi @DomMintago Yes, it must be enabled in the UEFI. It can also be enabled/disabled on Linux itself by checking the value of /sys/devices/system/cpu/intel_pstate/no_turbo 0 -> Turbo Mode is enabled 1 -> Turbo Mode is disabled

When Turbo Mode is disabled, it absolutely helps to limit the max througput of your Thunderbolt interfaces to get a stable data transfer rate: (replace "en06" with your interface name)

tc qdisc add dev en06 root tbf rate 10gbit burst 32m latency 400ms

For me, 10gbit was the sweet spot for low to none retries and a almost constant transfer rate of 10 Gbps.

To delete the limit:

tc qdisc del dev en06 root

iperf3 test with Turbo Mode disabled and throughput limited to 10gbit

Connecting to host 10.0.0.2, port 5201
[  5] local 10.0.0.1 port 40840 connected to 10.0.0.2 port 5201
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-1.00   sec  1.19 GBytes  10.3 Gbits/sec   35   2.26 MBytes
[  5]   1.00-2.00   sec  1.16 GBytes  9.98 Gbits/sec    3   2.26 MBytes
[  5]   2.00-3.00   sec  1.16 GBytes  10.0 Gbits/sec    4   2.26 MBytes
[  5]   3.00-4.00   sec  1.16 GBytes  9.98 Gbits/sec    0   2.26 MBytes
[  5]   4.00-5.00   sec  1.16 GBytes  9.99 Gbits/sec    0   2.26 MBytes
[  5]   5.00-6.00   sec  1.16 GBytes  9.99 Gbits/sec    0   2.26 MBytes
[  5]   6.00-7.00   sec  1.16 GBytes  9.99 Gbits/sec    0   2.26 MBytes
[  5]   7.00-8.00   sec  1.16 GBytes  10.0 Gbits/sec    0   2.26 MBytes
[  5]   8.00-9.00   sec  1.16 GBytes  9.99 Gbits/sec    0   2.26 MBytes
[  5]   9.00-10.00  sec  1.16 GBytes  9.98 Gbits/sec    0   2.26 MBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  11.7 GBytes  10.0 Gbits/sec   42            sender
[  5]   0.00-10.00  sec  11.7 GBytes  10.0 Gbits/sec                  receiver

Yeah my turbo is on. Limiting throughput does help, I'm just wondering why my retry is so high with the same setup as others

@DamianRyse
Copy link

@DomMintago have you tried another cable? I got one that is "Intel Thunderbolt certified" or something like that.

@Wyox
Copy link

Wyox commented Aug 21, 2025

I've had similar problems with the Retr and I assume this is due to the fact I had the scaling govenor set to powersave. Performance was fine expect for the high Retr so as suggested above I've also tried

# Ensure turbo is on
echo "0" > /sys/devices/system/cpu/intel_pstate/no_turbo
# Ensure that Turbo speed goes to the max
echo 100 > /sys/devices/system/cpu/intel_pstate/max_perf_pct

# Get you performance cores for the command below
cat /sys/devices/cpu_core/cpus && cat /sys/devices/cpu_atom/cpus

# Apply IRQ affinity to performance cores
grep thunderbolt /proc/interrupts | cut -d ":" -f1 | xargs -I {} sh -c 'echo 0-7 | tee "/proc/irq/{}/smp_affinity_list"'

I've went multiple routes after to try and figure out a way to solve the issue without switching the cpu govenor and the script below seems to do the trick for me.

It puts the CPU cores that are used for Thunderbolt IRQ into the highest "performance" preference while keeping others to "balance_power".

# Powersaving measures
echo "powersave" | tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
echo "balance_power" | tee /sys/devices/system/cpu/cpu*/cpufreq/energy_performance_preference
echo 10 | tee /sys/devices/system/cpu/cpu*/power/energy_perf_bias


# Determine the cores that are used for Thunderbolt IRQ. Afaik each port if used to link nodes uses 2 cores for IRQs, 1 RX and 1 TX.
# So if 2 nodes are connected, 4 P cores should be set to performance

THUNDERBOLT_IRQS=$(grep thunderbolt /proc/interrupts | cut -d ":" -f1)
PCORES=$(cat /sys/devices/cpu_core/cpus)
for irq in $THUNDERBOLT_IRQS; do

    IRQ_ON_CPU=$(cat /proc/irq/$irq/effective_affinity_list)

    # Only apply to the cores that need it to save more power
    IRQ_INTERUPTS_ON_CORE=$(awk -v irq="$irq:" -v cpu="$IRQ_ON_CPU" '$1 == irq {print $(cpu + 2)}' /proc/interrupts)
    # Attempt to filter the right cores after a reboot and iperf to each node
    if [ "$IRQ_INTERUPTS_ON_CORE" -gt 10 ]; then
      echo "Applying performance mode que to fact that there were interrupts on this core $IRQ_INTERUPTS_ON_CORE"
      echo "IRQ: $irq on core $IRQ_ON_CPU"
      cat /proc/irq/$irq/smp_affinity_list

      echo "performance" | tee /sys/devices/system/cpu/cpu$IRQ_ON_CPU/cpufreq/energy_performance_preference
      echo "performance applied to $IRQ_ON_CPU"        
    fi
done

There is still improvements in the script. If the kernel decides to switch the cores used for IRQ due to the affinity change, the performance preference is also applied to the previously used cores. But for me this reduced the Retr by a good amount

Connecting to host 10.0.0.82, port 5201
[  5] local 10.0.0.83 port 55778 connected to 10.0.0.82 port 5201
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-1.00   sec  3.05 GBytes  26.2 Gbits/sec   33   3.25 MBytes
[  5]   1.00-2.00   sec  3.05 GBytes  26.2 Gbits/sec   18   3.25 MBytes
[  5]   2.00-3.00   sec  2.95 GBytes  25.3 Gbits/sec   22   3.25 MBytes
[  5]   3.00-4.00   sec  3.07 GBytes  26.4 Gbits/sec    4   3.25 MBytes
[  5]   4.00-5.00   sec  3.08 GBytes  26.5 Gbits/sec    3   3.25 MBytes
[  5]   5.00-6.00   sec  3.06 GBytes  26.3 Gbits/sec    5   3.25 MBytes
[  5]   6.00-7.00   sec  3.06 GBytes  26.3 Gbits/sec    7   3.25 MBytes
[  5]   7.00-8.00   sec  3.04 GBytes  26.1 Gbits/sec    8   3.25 MBytes
[  5]   8.00-9.00   sec  3.07 GBytes  26.3 Gbits/sec   27   3.18 MBytes
[  5]   9.00-10.00  sec  3.06 GBytes  26.3 Gbits/sec    8   3.18 MBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-10.00  sec  30.5 GBytes  26.2 Gbits/sec  135             sender
[  5]   0.00-10.00  sec  30.5 GBytes  26.2 Gbits/sec                  receiver

@archiebug
Copy link

I manged to upgrade ceph to squid using the proxmox guides. I still get the 26 Gbit/s data rate as well. Is there a quick list of next steps to do to get to 9.0?

  1. run upgrade script checker and make sure there are no errors
  2. remedy the frr.service issues (comment out frr.service restart commands in scrtipts). From the initial setup guide, it appears that it lo and en0x under the if-up.d folder. Is there an example to what those should look like now?
  3. follow proxmox guide to upgrade to 9.0

@ssavkar
Copy link

ssavkar commented Aug 23, 2025

I manged to upgrade ceph to squid using the proxmox guides. I still get the 26 Gbit/s data rate as well. Is there a quick list of next steps to do to get to 9.0?

  1. run upgrade script checker and make sure there are no errors
  2. remedy the frr.service issues (comment out frr.service restart commands in scrtipts). From the initial setup guide, it appears that it lo and en0x under the if-up.d folder. Is there an example to what those should look like now?
  3. follow proxmox guide to upgrade to 9.0

So everyone is a little different, for instance I did not make the changes in the if-up.d folder but instead had a dependencies.conf file in my services part of systems which essentially had the same functionality that I fully commented out. After that, with respect to each node, I very carefully followed the directions that proxmox has for the 8 to 9 update and kept double checking pve8to9 to see what warnings or failures arose to keep things all clean.

One thing I did that some have not is besides commenting out the frr files I had used to ensure they came up at the right time, I also (as was the case when you upgraded to squid) on each node set the noout flag to ensure no changes to the node in teh midst of the update.

So “ceph osd set noout”. I then after reboot unset the noout flag.

Only other thing I’d note is that at the end of the process on each node besides cleaning up apt/sources, I also had to remove some old system files and install a new one as suggested by the pve8to9 script which again noted some stale files that needed to still be taken care of.

I didn’t find the need to do much else so long as you really do follow the online instructions ProxMox has put together for the 8 to 9 upgrade.

I still have one node that isn’t part of a cluster which runs my opensense instance and I haven’t yet figured how to deal with that one. Since I can’t really move opensense off of it, at least not at the moment. And of course in the upgrade I’ll lose access to the internet if I tried to leave it as is. But may just deal with that at a later date, not like a real issue sticking with 8 for that one node.

*** oh and to your question as to what they should look like post install, I don’t think you have the same issues we all had with 8 so I have not had to modify anything further for frr to come up ok now.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment