Chapter 19
| Spanning Tree Commands
– 527 –
Default Setting
BPDU Guard: Disabled
Auto-Recovery: Disabled
Auto-Recovery Interval: 300 seconds
Command Mode
Interface Configuration (Ethernet, Port Channel)
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.
◆ Before enabling BPDU Guard, the interface must be configured as an edge port
with the spanning-tree edge-port command. Also note that if the edge port
attribute is disabled on an interface, BPDU Guard will also be disabled on that
interface.
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 (529)
spanning-tree spanning-disabled (537)
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)
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
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