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"Switchport monitor" behavior

Hi Cisco Community,

I have a Q in regards to the behavior of a Nexus 5K port configured as Trunk and with the switchport monitor option enabled. Here's the configuration of that port:

sh run interface et2/1

interface Ethernet2/1

description Voice_Sniff_toSACTS023

switchport mode trunk

switchport monitor

duplex full

and the configuration of the associated Local SPAN session:

sh monitor sess 1

   session 1


type              : local

state             : up

source intf       :

    rx            : Po83         

    tx            : Po83         

    both          : Po83         

source VLANs      :

    rx            :

source VSANs      :

    rx            :

destination ports : Eth2/1       

Legend: f = forwarding enabled, l = learning enabled

My question is... what occurs to the port if I put the session in shutdown mode with a "monitor session 1 shutdown" command? Does it becomes an active trunk and starts forwarding traffic? I've been digging at Cisco documentation but have not found a clear response about this other than "Does not participate in spanning tree while the SPAN session is active." from the following document:

I'm interested on the behavior as recently we were hit by a Network Loop right after we shutdown a couple of monitoring sessions where the destination ports were connected to a third switch.

Thank you all in advance for helping to give me a clue!


Juan Cruz

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