Allied Telesis AT-S62 - Manual (Page 487)

AT-S62 Management Software Menus Interface User’s Guide
Section IV: Spanning Tree Protocols 487
Table 14 lists the RSTP port costs with Auto-Detect.
Table 15 lists the RSTP port costs with Auto-Detect when the port is part
of a port trunk.
You can override Auto-Detect and set the port cost manually.
Port Priority
If two paths have the same cost, the bridges must select a preferred path.
In some instances this can involve the use of the port priority parameter.
This parameter is used as a tie-breaker when two paths have the same
cost. The lower the value, the higher the priority given to the port.
The range for port priority is 0 to 240. As with bridge priority, this range is
broken into increments, in this case multiples of 16. To select a port priority
for a port, you enter the increment of the desired value. Table 16 on
page 488 lists the values and increments. The default value is 128, which
is increment 8.
Table 14. RSTP Auto-Detect Port Costs
Port Speed Port Cost
10 Mbps 2,000,000
100 Mbps 200,000
1000 Mbps 20,000
Table 15. RSTP Auto-Detect Port Trunk Costs
Port Speed Port Cost
10 Mbps 20,000
100 Mbps 20,000
1000 Mbps 2,000