Digisol DG-GS1550, Management Manual

Page: 521 / 665

Spanning Tree Commands
4-221
4
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: 0-4094, no leading zeroes)
• cost - Path cost for an interface. (Range: 0 for auto-configuration, 1-65535
for short path cost method25, 1-200,000,000 for long path cost method)
The recommended path cost range is listed in Table 4-62 on
page 4-214. The recommended path cost is listed in Table 4-63 on
page 4-214.
Default Setting
By default, the system automatically detects the speed and duplex mode used
on each port, and configures the path cost according to the values shown
below. Path cost “0” is used to indicate auto-configuration mode. When the
short path cost method is selected and the default path cost recommended by
the IEEE 8021w standard exceeds 65,535, the default is set to 65,535.
• Ethernet – half duplex: 2,000,000; full duplex: 1,000,000; trunk: 500,000
• Fast Ethernet – half duplex: 200,000; full duplex: 100,000; trunk: 50,000
• Gigabit Ethernet – full duplex: 10,000; trunk: 5,000
• 10 Gigabit Ethernet – full duplex: 1000; trunk: 500
Command Mode
Interface Configuration (Ethernet, Port Channel)
Command Usage
• Each spanning-tree instance is associated with a unique set of VLAN IDs.
• This command is used by the multiple spanning-tree algorithm to determine
the best path between devices. Therefore, lower values should be assigned
to interfaces attached to faster media, and higher values assigned to
interfaces with slower media.
• Use the no spanning-tree mst cost command to specify auto-configuration
mode.
• Path cost takes precedence over interface priority.
Example
25. Use the spanning-tree pathcost method command on page 4-208 to set the path cost method.
Console(config)#interface ethernet ethernet 1/5
Console(config-if)#spanning-tree mst 1 cost 50
Console(config-if)#