Configuring System Parameters

STP/Rapid Spanning Tree Protocol (RSTP) parameters that may affect network convergence include the network diameter, hello time, and timeout period for waiting for Bridge Protocol Data Units (BPDUs) from the upstream (3 x hello time x time factor). Therefore, STP/RSTP parameters need to be set properly to help implement rapid network convergence.

Procedure

Run system-view
The system view is displayed.
Run stp bridge-diameter diameter
The network diameter is configured.
- RSTP uses a single spanning tree instance on the entire network, which cannot prevent the performance from deteriorating when the network scale grows. Therefore, the network diameter cannot be larger than 7.
- It is recommended that you run the stp bridge-diameter diameter command to set the network diameter. Then, the device calculates the optimal Forward Delay period, Hello time, and Max Age period based on the set network diameter.
Run stp timer-factor factor
The timeout period for waiting for BPDUs from the upstream of a device is set.
(Optional) If the current device is at the edge of a network, run both or either of the following commands as needed:
- To configure all ports on the devices as edge ports, run the stp edged-port default command.
  
  After ports on a network edge device are configured as edge ports, the ports no longer participate in spanning tree calculation. This speeds up network topology convergence and improves network stability.
- To configure all ports on the devices as BPDU filter ports, run the stp bpdu-filter default command.
  
  After ports on a network edge device are configured as BPDU filter ports, the ports no longer process or send BPDUs.
After the stp bpdu-filter default and stp edged-port default commands are run in the system view, all ports on the device no longer actively send BPDUs or negotiate with directly-connected ports; instead, all the ports are in the Forwarding state. This may lead to a loop on the network, causing broadcast storms. Exercise caution when running these commands.
(Optional) To set the Forward Delay period, Hello time, and Max Age period, perform the following operations:
- To set the Forward Delay period for a device, run the stp timer forward-delay forward-delay command.
- To set the Hello time for a device, run the stp timer hello hello-time command.
- To set the Max Age period for a device, run the stp timer max-age max-age command.
The values of the Hello time, Forward Delay period, and Max Age period must comply with the following formulas. Otherwise, networking flapping occurs.
- 2 × (Forward Delay - 1.0 second) >= Max Age
- Max Age >= 2 × (Hello Time + 1.0 second)
Run commit
The configuration is committed.