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Double network bandwidth consumption than rostopic bw! ROS1 with VPN

Hi

I see expected network bandwidth consumption on physical private LAN. But I see double network bandwidth consumption with a VPN (globalprotect). The VPN is being used to connect nodes through internet. I attach a snap below: image description Is there anyone observing the same issue? Any solution? (Sorry if it is a VPN specific issue)

Master:
export ROS_IP=10.72.111.47
export ROS_MASTER_URI=http://10.72.111.47:11311
(e.g.) rosrun image_publisher image_publisher /opt/ros/noetic/share/rviz/images/splash.png


Slave
export ROS_IP=10.72.111.59
export ROS_MASTER_URI=http://10.72.111.47:11311

Asked by JeyP4 on 2023-07-29 06:41:50 UTC

Comments

Please tell us:

  1. How many images per second are you trying to publish?
  2. Please edit your description to show us some exact output from the "rostopic bw" command.
  3. What exactly are you measuring with this "system monitor"?

Asked by Mike Scheutzow on 2023-07-29 15:54:07 UTC

Thanks @Mike Scheutzow. I made an important observation and performed a major edit in the issue. Double bandwidth consumption is only observed with VPN use.

Asked by JeyP4 on 2023-07-29 17:25:47 UTC

Answers

VPNs work by wrapping one IP packet with another IP packet. What you're seeing is the network stack counting each VPN packet twice: the 1st time when it arrives, and the 2nd time when the "unwrapped" packet is sent back into the network stack for delivery to your app.

This is just a VPN artifact - the bandwidth "on the wire" is not really doubled.

Asked by Mike Scheutzow on 2023-07-30 07:38:12 UTC

Comments

@Mike Scheutzow.

The problem is that it is consuming double 4G bandwidth. image description

My doubt is VPN encryption overhead, but I don't know how to change the encryption protocol of Globalprotect app!!

Asked by JeyP4 on 2023-07-30 11:05:19 UTC