Dell N2000 Series, Configuration Manual

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Configuring the Spanning Tree Protocol
What are the Optional STP Features?
The Dell Networking 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.