Administrator Guide

Table 68. Default Values for Port Cost
Port Cost Default Value
100-Mb/s Ethernet interfaces 200000
1-Gigabit Ethernet interfaces 20000
10-Gigabit Ethernet interfaces 2000
Port Channel with 100 Mb/s Ethernet interfaces 180000
Port Channel with 1-Gigabit Ethernet interfaces 18000
Port Channel with 10-Gigabit Ethernet interfaces 1800
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.
Configuring an EdgePort
The EdgePort feature enables interfaces to begin forwarding traffic 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:
Configure 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).
• The reset linecard 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.
Per-VLAN Spanning Tree Plus (PVST+)
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