H3C Technologies H3C S12500 Series Switches - Manual (Page 107)

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Configuring protection functions
A spanning tree device supports the following protection functions:
• BPDU guard
• Root guard
• Loop guard
• TC-BPDU guard
Enabling BPDU guard
IMPORTANT:
BPDU guard does not take effect on loopback-testing-enabled ports. For more information about
loopback testing, see
Interface Configuration Guide.
For access layer devices, the access ports can directly connect to the user terminals (such as PCs) or file
servers. The access ports are configured as edge ports to allow rapid transition. When these ports
receive configuration BPDUs, the system automatically sets the ports as non-edge ports and starts a new
spanning tree calculation process. This causes a change of network topology. Under normal conditions,
these ports should not receive configuration BPDUs. However, if someone forges configuration BPDUs
maliciously to attack the devices, the network will become instable.
The spanning tree protocol provides the BPDU guard function to protect the system against such attacks.
With the BPDU guard function enabled on the devices, when edge ports receive configuration BPDUs,
the system will close these ports and notify the NMS that these ports have been closed by the spanning
tree protocol. Ports disabled in this way will be re-activated by the device after a detection interval. For
more information about this detection interval, see Fundamentals Configuration Guide.
Configure BPDU guard on a device with edge ports configured.
To enable BPDU guard:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enable the BPDU guard
function for the switch.
stp bpdu-protection
By default, BPDU guard is
disabled.
Enabling root guard
IMPORTANT:
On a port, the root guard function and the loop guard function are mutually exclusive.
The root bridge and secondary root bridge of a spanning tree should be located in the same MST region.
Especially for the CIST, the root bridge and secondary root bridge are put in a high-bandwidth core
region during network design. However, due to possible configuration errors or malicious attacks in the
network, the legal root bridge might receive a configuration BPDU with a higher priority. The current
legal root bridge will be superseded by another device, causing an undesired change of the network