Wifi traffic delays UDP messages over Ethernet

Hello,

My setup is a Jetson Orin Nano Developer Kit with Tegra release 35.5.0 / Jetpack 5.1.3 (flashed with SDK manger).

I have custom robotic hardware connected to the eth0 interface and communicate with it using UDP on a high priority thread. I send a message on this interface and typically get a response after 0.1ms with relatively low timing jitter.

Once I start putting unrelated traffic on the wifi network wlan0 I start to see delay spikes of up to 2ms in the incoming UDP messages on the eth0 interface. My suspicion is that this could be some kernel or OS setting or some unfortunate priority configuration?

Some more detail on how the delay is measured:

After a message is sent to the robotic hardware via UDP on eth0 the reply usually arrives after 0.1-0.2 ms with spikes of up to 0.4 ms. This is measured using tshark and wireshark.

Once I run iperf -c [ip] -b 1000M on the dev-kit to put traffic on the wifi network I repeat the measurements and the spikes will be much larger around 1.6ms.

Hi georg.wiedebach,

Is the delay issue happening for your robotic hardware only?
Or it can also be reproduced with ethernet connecting to a host PC?
If so, please share the detailed reproduce steps(including every commands you used) for us to verify it locally.

Could you help to ensure the network configuration (e.g., IP addresses, subnet masks, etc.) for both interfaces(ethernet and wifi) is correct and does not overlap?

Hi KevinFFF,

I will try to reproduce with a host PC and get back to you.

In the meantime, the network configuration on the Jetson is as follows (using netplan)

(1) the “robotic hardware” interface

network:
  ethernets:
    eth0:
      optional: true
      addresses: [192.168.2.1/24]
  version: 2

(2) the wifi network with unrelated traffic

network:
  wifis:
    wlan0:
      optional: true
      dhcp4: no
      addresses: [192.168.1.211/24]
      access-points:
         [...]
  version: 2

There is no update from you for a period, assuming this is not an issue any more.
Hence we are closing this topic. If need further support, please open a new one.
Thanks

Thanks!
Please let us know the result and share the steps for us to verify it locally.