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Enhancements
Release L.10.20 Enhancements
Spanning Tree Per-Port BPDU Filtering
The STP BPDU filter feature allows control of spanning-tree participation on a per-port basis. It can
be used to exclude specific ports from becoming part of spanning tree operations. A port with the
BPDU filter enabled will ignore incoming BPDU packets and stay locked in the spanning-tree
forwarding state. All other ports will maintain their role.
Here are some sample scenarios in which this feature may be used:
■ To have STP operations running on selected ports of the switch rather than every port of the
switch at a time.
■ To prevent the spread of errant BPDU frames.
■ To eliminate the need for a topology change when a port's link status changes. For example,
ports that connect to servers and workstations can be configured to remain outside of
standard spanning-tree operations.
■ To protect the network from denial of service attacks with spoofing spanning-tree BPDUs
by dropping incoming BPDU frames.
Note
BPDU protection imposes a more secure mechanism that implements port shut down and a detection
alert when an errant BPDU frame is received (see page 49 for details). BPDU protection will take
precedence over BPDU filtering if both features have been enabled on the same port.
Configuring STP BPDU Filters
The following commands allow you to configure BPDU filters via the CLI.
For example, to configure BPDU filtering on port a9, enter:
ProCurve(config)# spanning-tree a9 bpdu-filter
Caution
Ports configured with the BPDU filter mode remain active (learning and forward frames); however,
spanning-tree cannot receive or transmit BPDUs on the port. The port remains in a forwarding state,
permitting all broadcast traffic. This can create a network storm if there are any loops (that is, trunks
or redundant links) using these ports. If you suddenly have a high load, disconnect the link and
remove (“no”) the bpdu-filter.
Syntax: [no] spanning-tree <port-list | all> bpdu-filter
Enables/disables the BPDU filter feature on the specified port(s).
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