Administrator Guide

Modifying Interface Parameters
On interfaces in Layer 2 mode, you can set the port cost and port priority values.
• Port cost — a value that is based on the interface type. The previous table lists the default values. The greater the port cost, the less
likely the port is selected to be a forwarding port.
• Port priority — inuences the likelihood that a port is selected to be a forwarding port in case that several ports have the same port
cost.
To change the port cost or priority of an interface, use the following commands.
• Change the port cost of an interface.
INTERFACE mode
spanning-tree rstp cost cost
The range is from 0 to 65535.
The default is listed in the previous table.
• Change the port priority of an interface.
INTERFACE mode
spanning-tree rstp priority priority-value
The range is from 0 to 15.
The default is 128.
To view the current values for interface parameters, use the show spanning-tree rstp command from EXEC privilege mode.
Conguring an EdgePort
The EdgePort feature enables interfaces to begin forwarding trac approximately 30 seconds sooner.
In this mode an interface forwards frames by default until it receives a BPDU that indicates that it should behave otherwise; it does not go
through the Learning and Listening states. The bpduguard shutdown-on-violation option causes the interface hardware to shut
down when it receives a BPDU. When only bpduguard is implemented, although the interface is placed in an Error Disabled state when
receiving the BPDU, the physical interface remains up and spanning-tree drops packets in the hardware after a BPDU violation. BPDUs are
dropped in the software after receiving the BPDU violation. This feature is the same as PortFast mode in Spanning Tree.
CAUTION
: Congure EdgePort only on links connecting to an end station. If you enable EdgePort on an interface connected to a
network, it can cause loops.
Dell Networking OS Behavior: Regarding bpduguard shutdown-on-violation behavior:
• If the interface to shut down is a port channel, all the member ports are disabled in the hardware.
• When you add a physical port to a port channel already in the Error Disable state, the new member port is also disabled in the hardware.
• When you remove a physical port from a port channel in the Error Disable state, the error disabled state is cleared on this physical port
(the physical port is enabled in the hardware).
• The reset stack-unit command does not clear the error disabled state of the port or the hardware disabled state. The interface
continues to be disables in the hardware.
• You can clear the Error Disabled state with any of the following methods:
• Perform an shutdown command on the interface.
• Disable the shutdown-on-violation command on the interface (the no spanning-tree stp-id portfast
[bpduguard | [shutdown-on-violation]] command).
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Rapid Spanning Tree Protocol (RSTP)