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Enabling BPDU guard
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 will automatically set these ports as non-edge ports and start a
new spanning tree calculation process. This will cause 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 routers, 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. The closed ports will be re-activated by the router after a detection interval. For more
information about this detection interval, see Fundamentals Configuration Guide.
Make this configuration on a router with edge ports configured.
To enable BPDU guard:
Step
1.
Enter system view.
2.
Enable the BPDU guard
function for the router.
NOTE:
BPDU guard does not take effect on loopback test-enabled ports. For more information about loopback
Interface Configuration Guide
testing, see
Enabling root guard
NOTE:
H3C recommends you to enable root guard.
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 may receive a configuration BPDU with a higher priority. The current legal
root bridge will be superseded by another router, causing an undesired change of the network topology.
As a result, the traffic that should go over high-speed links is switched to low-speed links, resulting in
network congestion.
To prevent this situation from happening, MSTP provides the root guard function. If the root guard
function is enabled on a port of a root bridge, this port will keep playing the role of designated port on
all MSTIs. Once this port receives a configuration BPDU with a higher priority from an MSTI, it
immediately sets that port to the listening state in the MSTI, without forwarding the packet (this is
equivalent to disconnecting the link connected with this port in the MSTI). If the port receives no BPDUs
with a higher priority within twice the forwarding delay, it will revert to its original state.
Make this configuration on a designated port.
To enable root guard:
Command
system-view
stp bpdu-protection
.
60
Remarks
N/A
By default, BPDU guard is
disabled.
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