Trunk Port Shutdown From One Side
The setting: two Catalyst switches. On each one of them I created two VLANs. A trunk between both switches is set up. Scenario: I shutdown the trunk port on side A: No more VLANs are detected on the local trunk port: However, side B’s trunk port is still untouched. And it shows a list of allowed VLANs on the trunk, as if nothing special has happened: Conclusion Even if the trunking seems to be OK on one switch, we should check the trunk on both sides of the switches.