Administrator Guide

NOTE: The Dell Networking OS implementation of PVST+ uses IEEE 802.1s costs as the default costs. Other
implementations use IEEE 802.1w costs as the default costs. If you are using Dell Networking systems in a multi-vendor
network, verify that the costs are values you intended.
To change the port cost or port priority of an interface, use the following commands.
• Change the port cost of an interface.
INTERFACE mode
spanning-tree pvst vlan cost.
The range is from 0 to 200000.
Refer to the table for the default values.
• Change the port priority of an interface.
INTERFACE mode
spanning-tree pvst vlan priority.
The range is from 0 to 240, in increments of 16.
The default is 128.
The values for interface PVST+ parameters are given in the output of the show spanning-tree pvst command, as previously
shown.
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 be shut down when it receives a BPDU. When you only implement
bpduguard, 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. EdgePort can cause loops if you enable it on
an interface connected to a network.
To enable EdgePort on an interface, use the following command.
• Enable EdgePort on an interface.
INTERFACE mode
spanning-tree pvst edge-port [bpduguard | shutdown-on-violation]
The EdgePort status of each interface is given in the output of the show spanning-tree pvst command, as previously shown.
Dell Networking OS Behavior: Regarding the bpduguard shutdown-on-violation command behavior:
• If the interface to be 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 an Error Disable state, the new member port is also disabled in the
hardware.
• When you remove a physical port from a port channel in an Error Disable state, the Error Disabled state is cleared on this physical
port (the physical port is enabled in the hardware).
• You can clear the Error Disabled state with any of the following methods:
– Perform a shutdown command on the interface.
Per-VLAN Spanning Tree Plus (PVST+)
619