Spanning tree with Portchannel (Loop incoming?)

[romanegger]

Dear Cisco Friends

I'm currently configuring 2 Switches to an additional Switch ( all 48 Ports, Catalyst 3560G) and i want to configure them as following (red = new):

PC = Portchannel

As you see, i already configured the ports on every switch and the last step i want to do is to ensure that when i will connect these 2 switches to my root switch, that there will be zero network issues like spanning tree recalculations.

currently the root switch (192.168.2.1) doesn't have any spanning tree configurations so do switches 2 and 3.

I'm afraid to just connect them together to make a huge chaos, so how can i ensure myself that there is no Loop or spanning tree issues without just trying it out?

(also maybe which spanning tree configurations you might find appropriate? simple ones are prefered))

Thanks for your help!

Greetings

[nspasov · Accepted solution]

Hi there. Here are a few things/suggestions that you should do:

1. If switch 1 is to be the root of your STP then you should configure it to be the root for all VLANs 

2. Configure "root guard" on all other ports to prevent other switches from becoming a root switch 

3. Ensure that all switches are running the same type of STP. For instance, RPVSTP

4. Configure the new switches with high STP priority

5. Ensure that the new switches are running in VTP "transparent" mode

6. You will have spanning-tree blocking but it should be happening on the port-channel that is between your two new switches

I hope this helps!

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