Concept Guide

Port Cost Default Value
Port Channel with two 10-Gigabit Ethernet interfaces 1800
Port Channel with two 40-Gigabit Ethernet interfaces 600
To change the port cost or priority of an interface, use the following commands.
1 Change the port cost of an interface.
INTERFACE mode
spanning-tree msti number cost cost
The range is from 0 to 200000.
For the default, refer to the default values shown in the table.
2 Change the port priority of an interface.
INTERFACE mode
spanning-tree msti number priority priority
The range is from 0 to 240, in increments of 16.
The default is 128.
To view the current values for these interface parameters, use the show config command from INTERFACE 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 be
shut down when it receives a BPDU. When you implement only
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 mstp edge-port [bpduguard | shutdown-on-violation]
Dell Networking OS Behavior: Regarding bpduguard shutdown-on-violation 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 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).
– You can clear the Error Disabled state with any of the following methods:
◦ Use the shutdown command on the interface.
◦ Disable the shutdown-on-violation command on the interface (using the no spanning-tree mstp edge-port
[bpduguard | [shutdown-on-violation]])
command).
Multiple Spanning Tree Protocol (MSTP)
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