The following lab test was conducted in response to client questions and requests for clarification regarding Spanning Tree Protocol (STP) interoperability between Dell and Cisco switches. The results show that the Dell Power Connect 6200 series switch behaved as any IEEE 802.1D-compliant bridge would when interacting with Cisco’s proprietary PVST+ protocol (per-VLAN Spanning-Tree). Since the most commonly deployed version of Spanning Tree is the Rapid Spanning Tree Protocol (RSTP – IEEE 802.1w), the Cisco switches in this lab were configured for rapid-PVST+ and the Dell switch was configured for the open standard 802.1w RSTP, which was incorporated into the 2004 version of the 802.1D standard.