Configuring Root Guard - H3C S5100-SI Operation Manual

Normally, no configuration BPDU will reach edge ports. But malicious users can attack a network by
sending configuration BPDUs deliberately to edge ports to cause network jitter. You can prevent this
type of attacks by utilizing the BPDU guard function. With this function enabled on a switch, the switch
shuts down the edge ports that receive configuration BPDUs and then reports these cases to the
administrator. Ports shut down in this way can only be restored by the administrator.
You are recommended to enable BPDU guard for devices with edge ports configured.
Configuration Prerequisites
MSTP runs normally on the switch.
Configuration procedure
Follow these steps to configure BPDU guard:
To do...
Enter system view
Enable the BPDU guard
function
Configuration example
# Enable the BPDU guard function.
<Sysname> system-view
[Sysname] stp bpdu-protection

Configuring Root Guard

A root bridge and its secondary root bridges must reside in the same region. The root bridge of the CIST
and its secondary root bridges are usually located in the high-bandwidth core region. Configuration
errors or attacks may result in configuration BPDUs with their priorities higher than that of a root bridge,
which causes a new root bridge to be elected and network topology jitter to occur. In this case, flows that
should travel along high-speed links may be led to low-speed links, and network congestion may occur.
You can avoid this problem by utilizing the root guard function. Ports with this function enabled can only
be kept as designated ports in all MSTIs. When a port of this type receives configuration BPDUs with
higher priorities, it turns to the discarding state (rather than become a non-designated port) and stops
forwarding packets (as if it is disconnected from the link). It resumes the normal state if it does not
receive any configuration BPDUs with higher priorities for a specified period.
Use the command...
system-view
stp bpdu-protection
1-35
Remarks
—
Required
The BPDU guard function is
disabled by default.