Chapter 19
| Spanning Tree Commands
– 538 –
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
11
, 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.
Table 96: Recommended STA Path Cost Range
Port Type Short Path Cost
(IEEE 802.1D-1998)
Long Path Cost
(IEEE 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
10G Ethernet 1-5 200-20,000
11. Use the spanning-tree pathcost method command to set the path cost method. The range
displayed in the CLI prompt message shows the maximum value for path cost. However,
note that the switch still enforces the rules for path cost based on the specified path cost
method (long or short).
Table 97: Default STA Path Costs
Port Type Short Path Cost
(IEEE 802.1D-1998)
Long Path Cost
(IEEE 802.1D-2004)
Ethernet 65,535 1,000,000
Fast Ethernet 65,535 100,000
Gigabit Ethernet 10,000 10,000
10G Ethernet 1,000 1,000
To Next Page
Loading...
Need help?
General