Spanning Tree Commands
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spanning-tree link-type
This command configures the link type for Rapid Spanning Tree and Multiple
Spanning Tree. Use the no form to restore the default.
Syntax
spanning-tree link-type {auto | point-to-point | shared}
no spanning-tree link-type
•auto - Automatically derived from the duplex mode setting.
•point-to-point - Point-to-point link.
•shared - Shared medium.
Default Setting
auto
Command Mode
Interface Configuration (Ethernet, Port Channel)
Command Usage
• Specify a point-to-point link if the interface can only be connected to exactly
one other bridge, or a shared link if it can be connected to two or more bridges.
• When automatic detection is selected, the switch derives the link type from the
duplex mode. A full-duplex interface is considered a point-to-point link, while
a half-duplex interface is assumed to be on a shared link.
• RSTP only works on point-to-point links between two bridges. If you designate
a port as a shared link, RSTP is forbidden. Since MSTP is an extension of
RSTP, this same restriction applies.
Example
spanning-tree mst cost
This command configures the path cost on a spanning instance in the Multiple
Spanning Tree. Use the no form to restore the default.
Syntax
spanning-tree mst instance_id cost cost
no spanning-tree mst instance_id cost
•instance_id - Instance identifier of the spanning tree.
(Range: 1-4094, no leading zeroes)
•cost - Path cost for an interface. (Range: 1-200,000,000)
The recommended range is -
- Ethernet: 200,000-20,000,000
- Fast Ethernet: 20,000-2,000,000
- Gigabit Ethernet: 2,000-200,000
Console(config)#interface ethernet ethernet 1/5
Console(config-if)#spanning-tree link-type point-to-point