Configuration Guide     328
Configuring Spanning Tree MSTP Configurations
Forward Delay Specify the interval between the port state transition from listening to 
learning. The default value is 15. It is used to prevent the network from 
causing temporary loops during the regeneration of spanning tree. The 
interval between the port state transition from learning to forwarding is also 
the Forward Delay. 
Tx Hold Count Specify the maximum number of BPDU that can be sent in a second. The 
default value is 5.
Max Hops Specify the maximum BPDU hop counts that can be forwarded in a MST 
region. The default value is 20. A switch receives BPDU, then decrements the 
hop count by one and generates BPDUs with the new value. When the hop 
reaches zero, the switch will discard the BPDU. This value can control the 
scale of the spanning tree in the MST region.
Note: Max Hops is a parameter configured in MSTP. You need not configure 
it if the spanning tree mode is STP/RSTP.
Note:
To prevent frequent network flapping, make sure that Hello Time, Forward Delay, and Max Age 
conform to the following formulas:
• 
2*(Hello Time + 1) <= Max Age
• 
2*(Forward Delay - 1) >= Max Age
2)  In the Global Config section, enable Spanning-Tree function and choose the STP mode 
as MSTP and click Apply.
Spanning-Tree Check the box to enable the spanning tree function globally.
Mode Select the desired spanning tree mode as STP/RSTP on the switch. By 
default, it’s STP.
STP: Specify the spanning tree mode as STP. 
RSTP: Specify the spanning tree mode as RSTP. 
MSTP: Specify the spanning tree mode as MSTP.