Switchport logs

[networkninja_]

Has anyone seen this kind of logs and can explain further on what it mean?
Started seeing many Switch port and Spanning tree logs for a specific port and want to see if we can get more information on what it means and the reason why it's occurring, there has been no changes on the end device itself

[rwiesmann]

...looks like this port 35 is flapping...what do you have connected on this port?

[CMR]

As @rwiesmann said, this is normal logs for the port simply going up and down, what are the times for these events? It could be a dodgy patch lead, power saving, or many other things.

[networkninja_]

These are display boards that are on the network, they are always on and no power saving settings have been set. I understand I should see these logs during a reboot or something along those lines but the device has not been powered off in days. They are occurring during the day and the logs are consistent for 20 min or so

[mloraditch]

You can run a cable test on the port to check that to some degree, but beyond that you are not likely going to be able to garner more info from the switch itself. The switch just knows the port is active or not, not why it has become active or inactive.

If you want to test the port itself you can always take the device (or another) and plug it directly into the port in your network closet and see if the issue reoccurs. There is always a small chance the port could have gotten damaged by a surge and seeing if another device has the same issue would isolate that enough to be able to probably get an RMA. Although support may ask you to factory reset once and see if the issue still reoccurs after that.

[Brash]

Try a different patch lead, patch port, switch port etc.

You could also try manually setting the speed at 100Mbps and see if it stays stable on that speed.

[michalc1 · Accepted solution]

I understand that the wording in the switchport logs can sometimes be confusing. Many customers initially suspect an RSTP (Rapid Spanning Tree Protocol) issue, but these logs typically reflect a physical layer change rather than a network protocol problem.

For example:

• 'Old 1Gfdx: new down + Designated → Disabled' indicates no data is flowing. This can happen when:
  • A computer is powered off or unplugged
  • A VoIP phone is powered off or disconnected
  • A TV or similar device is turned off or unplugged
  • Other similar scenarios
• 'Down → New 1Gfdx' means data is flowing again, and the port has successfully negotiated a 1Gbps full-duplex connection. This might occur when:
  • A computer is powered on or reconnected
  • A VoIP phone is powered on or plugged in
  • A TV or device is turned on or reconnected
  • Etc.

To help troubleshoot this further, please try moving the cable from port 35 to another available port on the switch. Ensure the new port’s configuration matches the original (e.g., speed, duplex, VLAN settings), and monitor whether the flapping persists.

Additionally, do you have a patch panel between the switch and the end device? If so, we recommend connecting another device directly to the port, bypassing the patch panel, to rule out any issues with the switchport or intermediate cabling.