SG350XG-2F10 flapping port

[madarasz]

Hi guys, 

I would like to ask you for help with my problem.

Description of environment:

2 switches SG350XG-2F10 in stack. 

ProLiant DL380 Gen10 with 2 network cards Adapter 1 - HPE Eth 10/25Gb 2p 640FLR-SFP28 Adptr, Adapter 2 - HP Ethernet 10Gb 2-port 530T Adapter

Adapter1 connected with both ports to unit2 port -XG11 and XG12

Adapter2 connected with port 1 to unit 1 port 7, and port2 to unit 2 port 7

The problem is the port7 of unit 1 is flapping. It does not matter if I connect it to unit1 or unit2 to any free port it is still flapping. We thougth the problem is the adapter but it was changed and problem still persist. If I will connect the cable to other switch which is not in the stack it works correct. 

Could anybody help me what should I try or what can be the problem? 

Thank you and have a nice day. 

Regards Martin

[marce1000]

   - Check port counters on the flapping ports , check error-related counters.

 M.

[madarasz]

Hi thank you for fast reply, There is 0 packets with errors. 

[marce1000]

 - Have devices at the other end such as the Proliant checked for networking errors through the tools that the operating system provides , in Windows you have for instance eventvwr , here is an example : https://kb.iu.edu/d/bfvh

 M.

[madarasz]

there is vsphere and I tried it to find cause the problem but without any network error.

[Georg Pauwen]

Hello,

sounds like it could be related to spanning tree. Can you try and disable spanning tree on port 7 of stack unit 1 ?

https://www.cisco.com/c/en/us/td/docs/switches/lan/csbms/350xseries/2_5_7/Administration/tesla-350-550/cb_350_chapter_11.html#ID-00003889

[madarasz]

Hi, Thank you, I tried it but same result of flapping