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New Member

Connecting 3 C2950s via gigabit without creating a loop!

I have 3 2950's with GBICs. I want to connect 2 of the 3 back to my 2 core switches via gigabit, but also need to have all 3 connected, preferably by GBIC. I'm using SM/LH back to the Cores. I want to be sure I don't create a loop when connecting the 3 devices together. Thanks for your help!

Cisco Employee

Re: Connecting 3 C2950s via gigabit without creating a loop!

There are 3 ways you can get the connectivity:

1. Uplink all the switches directly to the 2 core switches using 2 links from each 2950 to core1 and core2.This way all the switches will talk to each other via the core.

2. Do the cascading of the 3 2950's and connect the first port of the top 2950 to core1 and second port to the down 2950.Conect last switch's one port to the above 2950 and second port to the second core2 switch. This will create a loop but STP will take care of it and will block one of the port.

3. Connect one 2950 to core1 and another 2950 to core2 and then connect the last 2950 to the other 2950's. This is the worst design that anyone can setup and not recommended at all.

use option1 if possible always.

-amit singh

New Member

Re: Connecting 3 C2950s via gigabit without creating a loop!

Thank you. I wish number 1 was an option, but I'll have to go with number 2. Does it matter if they are all trunk ports or should the last one (the one connected to both the others be an access port)? I'm not even sure if that's possible.

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