H3C S5120-SI Series Command Reference Manual page 206

Note that:
After the network topology is stabilized, each non-root-bridge device forwards configuration
BPDUs to the surrounding devices at the interval of hello time to check whether any link is faulty.
Typically, if a device does not receive a BPDU from the upstream device within nine times the hello
time, it will assume that the upstream device has failed and start a new spanning tree calculation
process.
In a very stable network, this kind of spanning tree calculation may occur because the upstream
device is busy. In this case, you can avoid such unwanted spanning tree calculations by
lengthening the timeout time, thus saving the network resources. We recommend that you set the
timeout factor to 5, or 6, or 7 for a stable network.
Examples
# Set the timeout factor of the device to 7.
<Sysname> system-view
[Sysname] stp timer-factor 7
stp transmit-limit
Syntax
stp transmit-limit limit
undo stp transmit-limit
View
Layer 2 Ethernet port view, port group view, Layer 2 aggregate port view
Default Level
2: System level
Parameters
limit: Maximum number of BPDUs the port(s) can send within each hello time, in the range of 1 to 255.
Description
Use the stp transmit-limit command to set the maximum transmission rate of the port(s), that is, the
maximum number of BPDUs the port(s) can send within each hello time.
Use the undo stp transmit-limit command to restore the system default.
By default, the maximum transmission rate of all ports of the device is 10, that is, each port can send up
to 10 BPDUs within each hello time.
Note that:
Configured in Layer 2 Ethernet port view, the setting takes effect on the current port only;
configured in port group view, the setting takes effect on all member ports in the port group.
Configured in Layer 2 aggregate port view, the setting takes effect only on the aggregate port;
configured on a member port in an aggregation group, the setting can take effect only after the port
leaves the aggregation group.
A larger maximum transmission rate value represents more BPDUs that the port will send within
each hello time, but this means that more system resources will be used. An appropriate maximum
transmission rate setting can limit the speed at which a port sends BPDUs and prevent MSTP from
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