Switch suddenly shuts down

[LFITS]

I have a network with two new SG350X Switches in a Stack as core switch and some 8 Port SG250-08HP Switches in areas where not enough sockets are available.

When I connect the 8 Port Switch to the Uplink, the switches both react normally and realize the new connection and stay turned on.

When I connect the 8 Port Switch to a Client (Tower PC), the switch reacts normally and stays turned on.

When both the Uplink and the Client are connected, the 8 Port Switch suddenly is turned off and stays off until one connection is gone.

It is not just the port beeing turned off, it is the whole switch that is turned off.

Are there any ideas what could be the root of this?

[balaji.bandi]

Seems like some Loop or Spanntree issue here.

how is these ports configured, have you configured as Trunk ?

[LFITS]

I have not implemented any VLANs yet, so when i look at the VLAN Settings of the core switch most ports are Set to Access (1 U), just two ports are set to Trunk (1U, 2-4094I).

But i did not change these settings myself, i guess when attaching the other cisco switch it reconfigured to trunk, is that correct?

Should i set all Uplink Ports to Trunk Ports?

[balaji.bandi]

yes high level yes you need to configured UPlink port to Trunk, best to suggest post configuration or screenshot to understand better your network.

[Edwin Portillo]

Hi my friend,

Make sure you do not have a port violation configuration, for example:

protect	Drops all the packets from the insecure hosts at the port-security process level but does not increment the security-violation count.
restrict	Drops all the packets from the insecure hosts at the port-security process level and increments the security-violation count.
shutdown	Shuts down the port if there is a security violation.

[LFITS]

Hi Edwin,

in Port Management > Port Settings i see the Protection State as "Unprotected"

in Security > Port Security I see all Interfaces as Unlocked.

[LFITS]

It ended up to be a problem between the SG-250 Switches and the intel NICs i219-v and other i219 versions.

With all other NICs there were no problems, just with those. I ended up installing additional NICs to the PCs to get it working.

[alextabs]

Had the same issue with FW 2.5.8.15 (Nov 21) and Intel NICs in Zotac ZBOX. Same for my provider Modem.

Zyxel and HP Switches i had for testing don't show this behaviour.

No entries in the Log.

I am sure some securtity researcher can build an DoS with this, as this issue effectively shuts down the complete switch.