3Com Switch 8800 Configuration Guide Chapter 38 MSTP Region-configuration38-26The rate of the primary port in an aggregation group is determined by the sum of theport rates in this group. No calculation is performed for secondary port.z Non-aggregation portThe actual rate counts, but the rate is 0 if the port is down.2) Calculating the path costTable 38-18 details the correspondence between the rate range and the value range ofthe path cost of the ports.Table 38-18 Correspondence between the rate range and path cost rangeRate range Path cost range[0, 100] 2200 to (20 × rate)(100,1000] 220 to the integer of [(0.2 × rate)](1000,10000] 22 to the integer of [(0.002 × rate)]> 10000 1You can specify the intended standard by using the following commands.Perform the following configuration in system view.Table 38-19 Specifying the standard to be followed in path cost calculationOperation CommandSpecify the standard to be adopted when theswitch calculates the default path cost for theconnected linkstp pathcost-standard{ dot1d-1998 | dot1t legacy}Restore the default standard to be used undo stp pathcost-standardBy default, the switch calculates the default path cost of a port by the DOT1T standard.38.2.13 Configuring the Priority of a PortFor spanning tree calculation, the port priority is an importance factor to determine if aport can be elected as the root port. With other things being equal, the port with thehighest priority will be elected as the root port. On the MSTP switch, a port can havedifferent priorities in different STIs and plays different roles respectively. Thus the trafficfrom different VLANs can run over different physical links, thereby implementing theVLAN-based load-balancing.You can configure the port priority in the following ways.I. Configuration in system viewPerform the following configuration in system view.