EtherChannel, Spanning tree
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11-19-2021 04:00 PM
Hi guys, I'm new to the community and networking in general. I am just learning about Etherchannels and STP, but had a question.
I have set up two Etherchannels from say Switch one to Switch two, and also from Switch one to Switch three.
They both say they are in use, although when I execute the "show spanning-tree" command, it will show Port-channel 1 (to the root bridge) in a root state, and Port-Channel 2 (Not to the root bridge) in a blocking state.
That's all good, but my question arises when I see that the "show spanning-tree" command also shows me the physical interfaces that are being used in those port channels.
For example, PO1 is using F0/23 - 24, and PO2 is using F0/21 - 22, and the command shows 23/24 (to the root bridge) in a forwarding state, but also 21/22 in a forwarding state as well. 21/22 are configured in the PO2, which should, I think be in a blocking state? Should it even show these physical interfaces at all, or did I do something wrong?
Thanks for any help!
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LAN Switching
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11-19-2021 04:12 PM
Not sure until we see your diagram and output :
take example I have a similar setup triangle connected (one of the branch) each other here s output show for vlan 300
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11-19-2021 04:23 PM
Hello
@belsbree22 wrote:
when I see that the "show spanning-tree" command also shows me the physical interfaces that are being used in those port channels.
For example, PO1 is using F0/23 - 24, and PO2 is using F0/21 - 22, and the command shows 23/24 (to the root bridge) in a forwarding state, but also 21/22 in a forwarding state as well. 21/22 are configured in the PO2, which should, I think be in a blocking state? Should it even show these physical interfaces at all, or did I do something wrong?
STP regards the PC relates to a single logical stp instance, so multiple PC are blocked based on the PC not the specific interfaced within the PC.
Are you using any aggregation protocol (pagp, lacp)
Please rate and mark as an accepted solution if you have found any of the information provided useful.
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Kind Regards
Paul
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11-19-2021 04:32 PM
I forgot to attach these images of my show command outputs for reference.
For instance, my outputs do not look like balaji's.
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11-19-2021 05:03 PM
Thank you guys for the replies, I figured out why it showed the Port channel interface and the physical interfaces on "show spanning-tree".
It was because I didn't have those physical interfaces and the port channel interfaces with the same configuration.
Thank you!
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11-19-2021 05:12 PM
Glad you figured out the issue, so we mark as resolved now.. this community is always helpful for learning ..........
