Dell PowerConnect 7048P User Manual - Page 635

What are the Optional STP Features? The PowerConnect 7000 Series switches support the following optional STP features: • BPDU flooding • PortFast • BPDU filtering • Root guard • Loop guard • BPDU protection BPDU Flooding The BPDU flooding feature determines the behavior of the switch when it receives a BPDU on a port that is disabled for spanning tree. If BPDU flooding is configured, the switch will flood the received BPDU to all the ports on the switch which are similarly disabled for spanning tree. Port Fast The PortFast feature reduces the STP convergence time by allowing edge ports that are connected to end devices (such as a desktop computer, printer, or file server) to transition to the forwarding state without going through the listening and learning states. BPDU Filtering Ports that have the PortFast feature enabled continue to transmit BPDUs. The BPDU filtering feature prevents PortFast-enabled ports from sending BPDUs. If BPDU filtering is configured globally on the switch, the feature is automatically enabled on all operational PortFast-enabled ports. These ports are typically connected to hosts that drop BPDUs. However, if an operational edge port receives a BPDU, the BPDU filtering feature disables PortFast and allows the port to participate in the spanning-tree calculation. Enabling BPDU filtering on a specific port prevents the port from sending BPDUs and allows the port to drop any BPDUs it receives. Configuring the Spanning Tree Protocol 635