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I have switched network and on all access ports I've configured

spanning-tree portfast edge

When I enable

spanning-tree portfast networks

on trunk ports 1/0/51-52 every access port is blocked.

Do I have a loop?

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spanning-tree portfast network configures an interface for a neighbor network device (switch/bridge) - this likely isn't what you'd expect for portfast mode since the port starts up in blocked state. portfast network also uses UDLD/Bridge Assurance to protect against unidirectional links.

spanning-tree portfast edge is the "normal" portfast mode for end-node (access) ports. It skips the initial blocked state to provide L2 connectivity more quickly after "link up". Note that loop protection is temporarily compromised when a link starts up in the forwarding state, until the tree is converged.

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  • We only use portfast edge on the access ports. Now we are troubleshooting our network and believe that we have some STP issues - ports randomly goes down/up after some time. The trunk ports to other switches haven't any STP confuguration. But when we configure portfast network on the trunk ports to other switches every accessport of the switch goes in a blocked state. My team believes that it is caused by a loop in the network?! I have no idea... – sno0z3 Feb 7 at 21:08
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    Then you'll need to provide more information. Please add a network diagram and the (sanitized) configurations (using the { } function) of your switches to your question. – Zac67 Feb 7 at 21:32

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