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How to avoid the server connecting port transition to blocking state during STP re-convergence

Hello All,

I was working on a task to add a new link to the existing link running between Switch B,C and D. There was a an outage of 2 to 3 minutes for all the servers connecting behind the FW which in turn is connecting to the Nexus 5K.

While troubleshooting found the Firewall connected switch port went to blocking state during the RSTP re-convergence.


%STP-6-PORT_RANGE_STATE: new_state=blocking interface=port-channel22

As per my understanding the Switch Ports will go into a blocking state at the time of election process, when a switch receives a BPDU on a port that indicates a better path to the Root Switch

Please correct me if I'm wrong with my RSTP understanding?

On the configuration perspective to find a solution:

The switch port is configured as " switchport mode trunk" . In order to stop receiving the BPDUs we have to configure the command "spanning-tree port type trunk"

Would you please help me to know configuring the switch port as "spanning-tree port type trunk" will avoid the switch port to trasistion to blocking state during the next RSTP reconvergence?

Will there by any impact to the host when I change the switch port configuration to "spanning-tree port type trunk" from "switchport mode trunk"

thanks in advance for your help.



1 Reply 1

Philip D'Ath
VIP Alumni
VIP Alumni

On a Nexus, when connecting a trunk device which does not forward layer 2 frames out other ports (like an ASA), use:

spanning-tree port type edge trunk