Concept Guide

● Port priority — influences the likelihood that a port is selected to be a forwarding port in case that several ports have the
same port cost.
The following tables lists the default values for port cost by interface.
Table 73. 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
25-Gigabit Ethernet interfaces 1700
40-Gigabit Ethernet interfaces 1400
50-Gigabit Ethernet interfaces 1200
100-Gigabit Ethernet interfaces 200
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
Port Channel with 25-Gigabit Ethernet interfaces 1200
Port Channel with 50-Gigabit Ethernet interfaces 200
Port Channel with 100-Gigabit Ethernet interfaces 180
NOTE: The Dell EMC 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 EMC 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.
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Per-VLAN Spanning Tree Plus (PVST+)