CLI Reference Guide-R05

Chapter 17 | Spanning Tree Commands
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Command Usage
◆ An edge port should only be connected to end nodes which do not generate
BPDUs. If a BPDU is received on an edge port, this indicates an invalid network
configuration, or that the switch may be under attack by a hacker. If an
interface is shut down by BPDU Guard, it must be manually re-enabled using
the no spanning-tree spanning-disabled command if the auto-recovery
interval is not specified.
◆ BPDU guard can only be configured on an interface if the edge port attribute is
not disabled (that is, if edge port is set to enabled or auto with the spanning-
tree edge-port command).
Example
Console(config)#interface ethernet 1/5
Console(config-if)#spanning-tree edge-port
Console(config-if)#spanning-tree bpdu-guard
Console(config-if)#
Related Commands
spanning-tree edge-port (474)
spanning-tree spanning-disabled (483)
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, 1-200,000,000 for long path cost method)
9
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
Table 90: 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
9. 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).