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Connecting 2 Catalyst 2950's

Hello all!  I am trying to connect 2 catalyst 2950 switches and having some difficulty.  I have the crossover cable connected and the LEDs are both green.  I've setup the smart ports through the Network Assistant on both ports to 'Switch'.  When I look at the topology view in NA, the link between the 2 switches is gray and the State of it says 'BLK'.  I have a 3rd 2950 switch that these 2 are connected to as well, and those links are both green on the topology view and the state of those is 'FWD'.  I've tried different crossover cables and different ports on each end but no matter what I do, I can't get this link to green.  Anyone have suggestions or where to dig to troubleshoot?

Thanks!

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Re: Connecting 2 Catalyst 2950's

tnelsontime wrote:

Hello all!  I am trying to connect 2 catalyst 2950 switches and having some difficulty.  I have the crossover cable connected and the LEDs are both green.  I've setup the smart ports through the Network Assistant on both ports to 'Switch'.  When I look at the topology view in NA, the link between the 2 switches is gray and the State of it says 'BLK'.  I have a 3rd 2950 switch that these 2 are connected to as well, and those links are both green on the topology view and the state of those is 'FWD'.  I've tried different crossover cables and different ports on each end but no matter what I do, I can't get this link to green.  Anyone have suggestions or where to dig to troubleshoot?

Thanks!

Tony

Sounds like STP (Spanning tree) has blocked this connection. If all 3 switches are interconnected then there will be a L2 loop and one link will have to be blocked. This is normal and it is what you need otherwise all your switches could go down.

Note if you have multiple vlans on each link ie. each link is a trunk between the switches then you can alternate which link is blocked per vlan.

Jon

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