I've got seven 3500XL switches at a remote site that are gigastacked and have "switchport mode trunk" on all gigastack interfaces. What's the preferred way to remotely change trunking to Dot1q. I discovered in the lab that I can't just add "switchport trunk encap dot1q". This locked up the management VLAN on all switches and I lost connectivity. Debugging spanning-tree events revealed unknown Dot1q BPDUs forced blocking on all VLANS. Good thing I didn't try this at a production site. Looking for any sugguestions...
