hikaru2001
Topic Author
Posts: 31
Joined: 18 Feb 2019, 04:13

Reestablish network connection after the ETH cable replugged in

02 Nov 2020, 08:17

Hello guys,

After I plug out the ethernet cable from RevPi Core3 and plug it in again. The ethernet connection won't be reestablished. My laptop can't ping RevPi Core 3 again until I power on RevPi Core 3 again.
Is that normal? How can I do some settings in order to make RevPi Core3 restart ethernet connection automatically?
Thank you so much!
 
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dirk
KUNBUS
Posts: 1426
Joined: 15 Dec 2016, 13:19

Re: Reestablish network connection after the ETH cable replugged in

02 Nov 2020, 17:04

Hello hikaru2001, I need more information. Can you send me a sos report?
sudo apt update
sudo apt install revpi-tools
revpi-sos
It works like so:
pi@RevPi40302:~ $ revpi-sos
The report will be generated under folder /tmp in a .tar.xz file, which
can be extracted with command: tar -Jxvf xxx.tar.xz in linux or 7zip in Windows.
And then some inspection can be done before it is sent to support@kunbus.com.
Are you going to continue (N/y)?y
report generating...

Your report has been generated and saved in:
/tmp/sosreport-RevPi40302-20201102163308.tar.xz

To make the report have better accessibility, the ownership of the report
can be changed to the current user.
Are you going to proceed(N/y)?y
The ownership of /tmp/sosreport-RevPi40302-20201102163308.tar.xz has been changed to user:pi
Please have in mind that you agree to send us private data i.e. IP address.

Send the report to support@kunbus.com
 
hikaru2001
Topic Author
Posts: 31
Joined: 18 Feb 2019, 04:13

Re: Reestablish network connection after the ETH cable replugged in

03 Nov 2020, 03:16

Hi Dirk,

I have sent you the SOS report by email.
Today I try "sudo ip link set eth0 down && sudo ip link set eth0 up" and find that the connection-reestablish problem can be solved. The network connection will be rebuilt whenever the ethernet cable is plugged out and in again after that command is executed.
 
User avatar
dirk
KUNBUS
Posts: 1426
Joined: 15 Dec 2016, 13:19

Re: Reestablish network connection after the ETH cable replugged in

03 Nov 2020, 15:28

Hi, we have received the sos-report with thanks, discussed it in the RevPi Stand Up and roughly analyzed it:
We noticed the following things in the Kern.log shortly before the eth0 connection is restarted:
There are messages from the USB power management: "eth0: hardware isn't capable of remote wakeup".
One or more Logitech USB HID devices report "HID++ 2.0 device connected".
These are only rough hits but can be a good start for troubleshooting.

The command you describe and the solution is not quite clear to us.
Is it enough to enter the command only once after a connection loss and then not anymore?
Or every time the connection is lost.
 
hikaru2001
Topic Author
Posts: 31
Joined: 18 Feb 2019, 04:13

Re: Reestablish network connection after the ETH cable replugged in

06 Nov 2020, 09:09

Hi Dirk,

The command is only entered once, then the connection will always recover automatically after the cable is plugged out and in again.
 
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dirk
KUNBUS
Posts: 1426
Joined: 15 Dec 2016, 13:19

Re: Reestablish network connection after the ETH cable replugged in

10 Nov 2020, 15:37

Hi hikaru2001, this is interesting that you have to enter the command only once.

Is the command entered on the RevPi or on the laptop? So you need a HDMI and a USB Keyboard as you don't have SSH access to the RevPi.
Call ethtool if there is no more link and see if a physical link is displayed?
We have to reproduce the error so that we can understand what caused it.
Attachments
ethtool1.jpg
ethtool1.jpg (59.12 KiB) Viewed 922 times
 
hikaru2001
Topic Author
Posts: 31
Joined: 18 Feb 2019, 04:13

Re: Reestablish network connection after the ETH cable replugged in

12 Nov 2020, 05:30

Hi Dirk,

Sure the command is entered on RevPi!
After the error is reproduced, I call ethtool and the result is "Link deteted: yes", "Auto-negotiation: on".
 
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dirk
KUNBUS
Posts: 1426
Joined: 15 Dec 2016, 13:19

Re: Reestablish network connection after the ETH cable replugged in

12 Nov 2020, 15:26

Hi hikaru2001, please try the following:
  • Power cycle the RevPi
  • start a Wireshark capture on your Laptop
  • run the command on your RevPi "sudo tcpdump -i eth0 -C /tmp/capture.pcap"
  • pull the Ehternet cable and plug it again after a few seconds
  • ping the RevPi from your laptop - it should not be possible
  • stop and save the Wireshark capture on the laptop
  • cancel the tcpdump on the RevPi
  • run the command on your RevPi "ethtool -S eth0" to give out the error couters and other statistics and make a screenshot.
Send us everything.

Hopefully we'll see things clear then. Thank you for your work.
 
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dirk
KUNBUS
Posts: 1426
Joined: 15 Dec 2016, 13:19

Re: Reestablish network connection after the ETH cable replugged in

26 Nov 2020, 17:06

Hi hikaru2001, do you have updates for me? Is this issue still open?
 
hikaru2001
Topic Author
Posts: 31
Joined: 18 Feb 2019, 04:13

Re: Reestablish network connection after the ETH cable replugged in

27 Nov 2020, 02:57

Hi Dirk,

Sorry for my late reply! On some day of the second last week, the reestablish network connection problem didn't exist while I hadn't done anything to RevPi Core3. I want to simulate the error again for a long time, but not realized.
Maybe the issue can be closed. Thank you!

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