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mubashir_133429
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Jun 11, 2014

On shifting of F5 3600 from one cisco 4500 switch to Nexus 7 Vlan flapping started and we last the connectivity with some servers on that switch

We had an activity last night in which our F5 3400 two interfaces were configured in on Vlan on a Cisco 4500 switch, we did same configuration on Nexus 7009 and shifted these two interfaces to Nexus but all of a sudden some of our servers which were in cluster connected with that Nexus restarted and Vlan flapping error was coming on Nexus.

 

So we revert back our F5 activity. Would you please help me why this happened however configuration on both Switches was same.

 

2 Replies

  • Can you describe the STP configuration on the F5 and the old and new switches please? Any differences?

     

    Also, its not clear, are you using trunking and tagging and is this a single device?

     

  • Thanks, so one F5 with two tagged interfaces (carrying VLAN101), one to each switch?

     

    What STP protocol is running on the switches please?

     

    Pass through mode doesn't sound like a good idea to me;

     

    "Pass Through Specifies that when the BIG-IP system receives spanning tree frames (BPDUs), it forwards them to all other interfaces. This is the default setting. When you use Pass Through mode, the BIG-IP system is transparent to spanning tree BPDUs. When set to Pass Through mode, the BIG-IP system is not part of any spanning tree. Note that Pass Through mode is not part of the IEEE spanning tree protocol specifications."

     

    I'd suggest, especially if the switch ports run PortFast, that you change it to disabled.