202 C HAPTER 9: SPANNING T REE P ROTOCOLConnecting to STPSystems on LegacySwitch UnitsIf you are connecting your Switch to legacy units that support STP, notethe following: Your Switch supports one STP system; however legacy Switch units(for example, the SuperStack II Switch 1000) may support one STPsystem per VLAN. Consequently: If the legacy Switch units use a single VLAN and you connect yourSwitch to them using an untagged link, the STP system of yourSwitch and the STP system of the legacy Switch units arecombined. If the legacy Switch units use multiple VLANs and you connect yourSwitch to them using a VLT tagged link, the STP system of yourSwitch and the STP system of the legacy Switch units arecompletely separate. This means that if you connect your Switch toa legacy Switch unit using multiple VLT links, a loop may created. Some legacy units cannot use VLAN 16 if they are using STP. If yourSwitch is connected to one of these units, VLAN 16 traffic is blockedon the port.Enabling STP To enable STP on your Switch via the command line interface, see“Enabling and Disabling Spanning Tree on a Bridge” on page 116.To enable STP on your Switch via the web management interface:1 From the web interface, click the Configuration icon on the side-bar.2 Click the Advanced Stack Setup hotlink. The Advanced Stack Setup pageis displayed.3 From the Spanning Tree listbox, select Enabled.4 Click the Apply button.You cannot enable STP if you have set up any resilient links on the Switch.
