Why is the port not coming up

[Leerical]

Hello all, 

I am starting a lab that I am configuring myself and right off the bat when I connect the ports at least one will not come on although it says it is on when I look at the switch. Any clue as to why it isn't coming up. I have not configured anything I have just connected the ports. I've tried disconnecting and putting it in other ports and the problem just goes from one to the other. 

[Georg Pauwen]

Hello,

for router <--> switch connectivity, you need a straight through cable, it looks like you are using a crossover cable.

[Leerical]

Thanks, I changed that. However, I am referring to Sw1 to Sw2.

[Georg Pauwen · Accepted solution]

Hello,

sorry for the misunderstanding. What you are seeing is related to Spanning Tree Protocol, STP in short. Since you have redundant connections, one of the ports will be blocked in order to avoid a loop.

Check the link below to read up on what STP does:

https://fossbytes.com/spanning-tree-protocol-stp-operational-basics/