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I'm in the process of studying to renew my CCNP again. 3 years comes and goes awful fast! While working on my lab gear I thought I wonder if I can shut down STP on a single interface like I've done in HP and Delta networks in the past. This particular set up was 2 Cisco 3750 48 port poe. Version 12 something. I'll need to double check exact version.

I have interfaces 1-4 plugged directly into one another on the two switches. Port 1 to 1, 2 to 2, etc. The switches only had vlan 1. Port 1 on both switches were access ports and 2-4 were dynamic (default) but the operational mode was access in show int f1/0/2 switchport since there are no other vlans on the switches. Both switches were in mode rstp.

On the root switch I decide to use context sensitive help and see if I could stop STP on interface 1. Here's what I typed... Enable Config t Int f1/0/1 No Spanning-tree vlan 1 Exit Exit Show Spanning-tree vlan 1

The response I received was there was no spanning tree instance running! What the heck! I was on an interface. It was running just before that. It's easy to replicate as well.

Questions.. 1. Has anyone else ran into this or know if this is a known bug in version 12 or just a known "gotcha" ? (I'll get my exact version in a bit)

  1. I know this is going to sound elementary. Is there a way to turn STP off for a single interface? (not portfast or bpdu filter like I normally use).

Thank you for your time,

Fixitrod

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For question 1, I think it is normal behavior that you will type the command on interface level and it will be global config mode command

for your second question there is no option for disabling STP on the port level you can disable the STP on VLAN level only

BPDU filter and portfast will provide the expected behavior for disabling the STP on port level

  • I guess I didn't think number 1 through thoroughly because I can type another interface command in from interface config of another interface. Shutting down all stp just stunned me I guess. If portfast and bpdu filter are enabled not a single bpdu will go through? I ask for a particular reason. Cobranet audio devices tend to lock up with stp. Nobody can tell us why but we have proven it. I've had a top 10 college football stadium audio lockup and it never would if stp was off. I have NFL stadium as well but we learned this ahead of time thankfully. – Fixitrod Aug 24 '17 at 5:29

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