D-Link DGS-510 Reference Manual page 609

DGS-1510 Series Gigabit Ethernet SmartPro Switch CLI Reference Guide
spanning-tree guard root
no spanning-tree guard root
Parameters
None.
Default
By default, this option is disabled.
Command Mode
Interface Configuration Mode.
Command Default Level
Level: 12.
Usage Guideline
BPDU guard prevents a port from becoming a root port. This feature is useful for the service provider
to prevent external bridges to a core region of the network influencing the spanning tree active
topology, possibly because those bridges are not under the full control of the administrator.
When a port is guarded from becoming a root port, the port will only play the role as a designated port.
If the port receives the configuration BPDU with a higher priority, the port will change to the alternate
port, which is in the blocking state. The received superior factor will not participate in the STP
computation. The port will listen for BPDUs on the link. If the port times out the received superior
BPDU, it will change to the designated port role.
When a port changes to the alternate port state, due to the root guard, a system message will be
generated. This configuration will take effect for all the spanning-tree versions.
Example
This example shows how to configure to prevent Ethernet interface eth3/0/1 from being a root port.
Switch# configure terminal
Switch(config)# interface eth3/0/1
Switch(config-if)# spanning-tree guard root
Switch(config-if)#
65-10 spanning-tree link-type
This command is used to configure a link-type for a port. Use the no form of this command to revert to
the default setting.
spanning-tree link-type {point-to-point | shared}
no spanning-tree link-type
Parameters
point-to-point
shared
Default
The link type is automatically derived from the duplex setting unless explicitly configuring the link type.
Command Mode
Interface Configuration Mode.
Specifies that the port's link type is point-to-point.
Specifies that the port's link type is a shared media connection.
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