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Setting the timeout factor
About timeout factor
The timeout factor is a parameter used to decide the timeout period. The formula for calculating the
timeout period is: timeout period = timeout factor × 3 × hello time.
In a stable network, each non-root-bridge device forwards configuration BPDUs to the downstream
devices at the hello time interval to detect link failures. If a device does not receive a BPDU from the
upstream device within nine times the hello time, it assumes that the upstream device has failed.
Then, it starts a new spanning tree calculation process.
Restrictions and guidelines
As a best practice, set the timeout factor to 5, 6, or 7 in the following situations:
• To prevent undesired spanning tree calculations. An upstream device might be too busy to
forward configuration BPDUs in time, for example, many Layer 2 interfaces are configured on
the upstream device. In this case, the downstream device fails to receive a BPDU within the
timeout period and then starts an undesired spanning tree calculation.
• To save network resources on a stable network.
Procedure
1. Enter system view.
system-view
2. Set the timeout factor of the device.
stp timer-factor factor
The default setting is 3.
Configuring the BPDU transmission rate
About BPDU transmission rate
The maximum number of BPDUs a port can send within each hello time equals the BPDU
transmission rate plus the hello timer value.
The higher the BPDU transmission rate, the more BPDUs are sent within each hello time, and the
more system resources are used. By setting an appropriate BPDU transmission rate, you can limit
the rate at which the port sends BPDUs. Setting an appropriate rate also prevents spanning tree
protocols from using excessive network resources when the network topology changes.
Restrictions and guidelines
The BPDU transmission rate depends on the physical status of the port and the network structure.
As a best practice, use the default setting.
Procedure
1. Enter system view.
system-view
2. Enter interface view.
interface interface-type interface-number
3. Configure the BPDU transmission rate of the ports.
stp transmit-limit limit
The default setting is 10.
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