C
HAPTER
33
| Spanning Tree Commands
– 797 –
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
12
, 1-200,000,000 for long path
cost method)
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.
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 path cost method (page 789) is set to short, the maximum
value for path cost is 65,535.
12. Use the spanning-tree pathcost method command on page 789 to set the path cost
method.
Table 104: Recommended STA Path Cost Range
Port Type Short Path Cost
(IEEE 802.1D-1998)
Long Path Cost
(802.1D-2004)
Ethernet 50-600 200,000-20,000,000
Fast Ethernet 10-60 20,000-2,000,000
Gigabit Ethernet 3-10 2,000-200,000
Table 105: Default STA Path Costs
Port Type Short Path Cost
(IEEE 802.1D-1998)
Long Path Cost
(802.1D-2004)
Ethernet 65,535 1,000,000
Fast Ethernet 65,535 100,000
Gigabit Ethernet 10,000 10,000
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