Powerconnect 6248 Connectivity issue

Question

Currently have two different stacks of 6248's, Floor 1 has 4 switches and Floor 2 has 3. Periodically sometime in the night communication between floor 1 and 2 is lost. Originally there was fiber run between the floors when the issue originally started, a two port lag was then configured and the issue still occurred. Finally I switched the lag to a single cable run and am still seeing the issue. Usually a reboot of the 2nd floor stack resolves the issue.   Last night the issue happened again, I see the uplink port go from Forwarding to Blocking via STP in the buffer log. Once we had a tech onsite I tried disabling STP on the floor 1 uplink port and see it switched manually forwarding however the connection was still not working.   Was hoping I could review the configs with someone and work on correcting this issue.

DELL-Josh Cr · Answer

Hi, Is the firmware on the switches up to date? After disabling STP what was the state of the port? Was it still in blocking?

jambes · Answer

Hi Josh,

All switches are running latest firmware. After disabling STP on Floor 1 stack the port went into manual forwarding state however traffic was still working. Technician got onsite and I was hoping to check the status of the STP on the uplink port on floor 2 but connectivity was restored.

jambes · Answer

Bump

DELL-Josh Cr · Answer

You could try mirroring the port and see if it shows anything, maybe something is flooding the port and shutting it down.

jambes · Answer

Hi Josh,   Wireshark reports tons of pause_time 65535 quant and the mac address of the source points to VLAN 1 CPU of the switches on the 2nd floor.

DELL-Josh Cr · Answer

Is there a lot of traffic on that vlan? You may need a newer, faster switch.

jambes · Answer

Hi Josh,   There should be no traffic on that VLAN. Every port in that stack has been removed from that vlan.

DELL-Josh Cr · Answer

You could try turning off flow control.

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