Configuration restrictions and guidelines

The length of the forward delay timer is related to the network diameter of the switched network. The larger the network diameter is, the longer the forward delay time should be. If the forward delay timer is too short, temporary redundant paths might occur. If the forward delay timer is too long, network convergence might take a long time. As a best practice, use the automatically calculated value.

An appropriate hello time setting enables the device to promptly detect link failures on the network without using excessive network resources. If the hello time is too long, the device mistakes packet loss for a link failure and triggers a new spanning tree calculation process. If the hello time is too short, the device frequently sends the same configuration BPDUs, which wastes device and network resources. As a best practice, use the automatically calculated value.

If the max age timer is too short, the device frequently begins spanning tree calculations and might mistake network congestion as a link failure. If the max age timer is too long, the device might fail to promptly detect link failures and quickly launch spanning tree calculations, reducing the auto-sensing capability of the network. As a best practice, use the automatically calculated value.