15-5
Cisco ME 3800X and 3600X Switch Software Configuration Guide
OL-23400-01
Chapter 15 Configuring Optional Spanning-Tree Features
Configuring Optional Spanning-Tree Features
Configuring Optional Spanning-Tree Features
• Default Optional Spanning-Tree Configuration, page 15-5
• Optional Spanning-Tree Configuration Guidelines, page 15-5
• Enabling Port Fast, page 15-5 (optional)
• Enabling BPDU Guard, page 15-6 (optional)
• Enabling BPDU Filtering, page 15-7 (optional)
• Enabling EtherChannel Guard, page 15-8 (optional)
• Enabling Root Guard, page 15-9 (optional)
• Enabling Loop Guard, page 15-9 (optional)
Default Optional Spanning-Tree Configuration
Optional Spanning-Tree Configuration Guidelines
You can configure PortFast, BPDU guard, BPDU filtering, EtherChannel guard, root guard, or loop
guard if your switch is running PVST+, rapid PVST+, or MSTP.
Enabling Port Fast
An STP port with the Port Fast feature enabled is moved directly to the spanning-tree forwarding state
without waiting for the standard forward-time delay.
Caution Use Port Fast only when connecting a single end station to an access or trunk port. Enabling this feature
on an interface connected to a switch or hub could prevent spanning tree from detecting and disabling
loops in your network, which could cause broadcast storms and address-learning problems.
You can enable this feature if your switch is running PVST+, rapid PVST+, or MSTP.
Table 15-1 Default Optional Spanning-Tree Configuration
Feature Default Setting
Port Fast, BPDU filtering, BPDU guard Globally disabled (unless they are individually configured per STP port).
EtherChannel guard Globally enabled.
Root guard Disabled on all STP ports.
Loop guard Disabled on all STP ports.
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