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spanning-tree cost
This command configures the spanning tree path cost for the specified interface.
Use the
no
form to restore the default auto-configuration mode.
Syntax
spanning-tree
cost
cost
no spanning-tree cost
cost - The path cost for the port.
(Range: 0 for auto-configuration, 1-65535 for short path cost method
28
,
1-200,000,000 for long path cost method)
Table 33-2 Recommended STA Path Cost Range
Port Type Short Path Cost Long Path Cost
(IEEE 802.1D-1998) (802.1D-2004)
Gigabit Ethernet 2,000-65,535 2,000-200,000
10G Ethernet 200-20,000 200-20,000
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 8021D-2004 standard exceeds 65,535, the default is set to 65,535.
Table 33-3 Default STA Path Costs
Port Type Short Path Cost Long Path Cost
(IEEE 802.1D-1998) (802.1D-2004)
Gigabit Ethernet 10,000 10,000
10G Ethernet 1,000 1,000
Command Mode
Interface Configuration (Ethernet, Port Channel)
Command Usage
• This command is used by the Spanning Tree Algorithm to determine the best
path between devices. Therefore, lower values should be assigned to ports
attached to faster media, and higher values assigned to ports with slower
media.
• Path cost takes precedence over port priority.
• When the spanning-tree pathcost method (page 33-6) is set to short, the
maximum value for path cost is 65,535.
28. Use the spanning-tree pathcost method command on page 33-6 to set the path cost method.
33-12
Spanning Tree Commands
33