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Beginner

Interface consistently down on switch

I'm doing an exercise in packet tracer where I enable security measures on switches. There are three switches connected to each other that I am doing this to. In the process of attempting to do so, I noticed that when I connect the three switches, one of the interfaces on one of the switches is ALWAYS down. And on that switch nothing shows when I implement a show mac address-table command, there is no MAC address information listed for that interface as it is down. Is there a reason for this? Or is there something else I need to do to open that interface?  

 

I have attached a packet tracer file simply showing the topology I am speaking of. 

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Advocate

Re: Interface consistently down on switch

Hi @TheFox ,

 

The switches come with the spanning-tree protocol enabled.

This protocol prevents layer 2 loops from occurring.

To achieve this, turn off some interfaces to leave only one way to all possible destinations.

If you are a Cisco Networking Academy student, you are probably at CCNA2.

The STP protocol is studied in CCNA3, so I encourage you to continue advancing with your studies and continue with your curiosity.

 

Regards

3 REPLIES 3
Advocate

Re: Interface consistently down on switch

Hi @TheFox ,

 

The switches come with the spanning-tree protocol enabled.

This protocol prevents layer 2 loops from occurring.

To achieve this, turn off some interfaces to leave only one way to all possible destinations.

If you are a Cisco Networking Academy student, you are probably at CCNA2.

The STP protocol is studied in CCNA3, so I encourage you to continue advancing with your studies and continue with your curiosity.

 

Regards

Enthusiast

Re: Interface consistently down on switch


I agree with Luis, STP loop prevention is good thing and is on by default
Beginner

Re: Interface consistently down on switch

Thanks for the help. Makes sense!
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