Spanning Tree Commands
29-12
29
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
35
,
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)
35. Use the spanning-tree pathcost method command on page 29-6 to set the path cost method.
Table 29-2 Recommended STA Path Cost Range
Port Type IEEE 802.1D-1998 IEEE 802.1w-2001
Fast Ethernet 10-60 20,000-2,000,000
Gigabit Ethernet 3-10 2,000-200,000
Table 29-3 Recommended STA Path Cost
Port Type Link Type IEEE 802.1D-1998 IEEE 802.1w-2001
Fast Ethernet Half Duplex
Full Duplex
Trunk
19
18
15
200,000
100,000
50,000
Gigabit Ethernet Full Duplex
Trunk
4
3
10,000
5,000
Table 29-4 Default STA Path Costs
Port Type Link Type IEEE 802.1w-2001
Fast Ethernet Half Duplex
Full Duplex
Trunk
200,000
100,000
50,000
Gigabit Ethernet Full Duplex
Trunk
10,000
5,000
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