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NEXUS9K Port-channel issue



I'm quite new regarding NEXUS 9000 series switch so bear with me please. I had a strange behaviour regarding the port-channel. I have 2 NEXUS9K switches connected over VPC so it acts like one logical switch. On this setup I have aporximatly 10 Port-channels towards the switch. When I was testing this setup I shut down all interfaces on both Nexus switches and then turned them on again.


The results was that all Port-channels went back up again after the interfaces were UP except for one on the secondary NEXUS switch that was stuck in (STP set port state failure), and the physical interface was errdisabled.


The log showed : "%STP-2-SET_PORT_STATE_FAIL: Port state change req to PIXM failed, status = 0x12 [fu hashtable key not present] vdc 1, tree id 0, num ports 6, ports state FW
D, opcode MTS_OPC_PIXM_SET_MULT_CBL_VLAN_BM_FOR_MULT_PORTS, msg id (-945035772), rr_token 0x47ABE604"


On the first Nexus switch the physical interface went normaly up and Port-channel was UP. Well all fine I suppose , the traffic should still flow through first Nexus switch. But when I tested the reachability and other kind of network traffic, sometimes devices over this port-channel were reachable and othetimes they were down. It looked like the switch was still trying to pass traffic over the secondary Nexus switch. Could this happend because from the perspective of the switch that was connected to both Nexus switches both interfaces were active ?


When I shut/no shut the Port-channel it went UP on the secondarty switch and everything started to work normaly.


Could this be a BUG , or is this a normal behaviour or something else.


Thank you in advance

VIP Advisor

VIP Master

Not sure it may be a bug - but before we confirm that - check the below config. ( show version)


If the Switches are in vPC Mode, you need to configure both the switches under port-channel vPC PO number example 

on both the nexus to remediate the spanning-tree loops.


interface port-channel 20



vpc 20


Once you do this Port-channel go down and come up, then traffic from the downside switch can pass the traffic on both the nexus?

if this is not the case please provide more information and config.



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paul driver
VIP Mentor


show vpc
show vpc consistency-parameters global
show vpc consistency-parameters interface xxx

kind regards

Please rate and mark posts accordingly if you have found any of the information provided useful.
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