Allied Telesis AT-S63 - Manual (Page 253)

AT-S63 Management Software Menus Interface User’s Guide
Section II: Advanced Features 253
Table 14 lists the STP port costs with Auto-Detect when a port is part of a
port trunk.
Table 15 lists the RSTP port costs with Auto-Detect.
Table 16 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 port 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 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
Table 14. STP Auto-Detect Port Trunk Costs
Port Speed Port Cost
10 Mbps 4
100 Mbps 4
1000 Mbps 2
Table 15. RSTP Auto-Detect Port Costs
Port Speed Port Cost
10 Mbps 2,000,000
100 Mbps 200,000
1000 Mbps 20,000
Table 16. RSTP Auto-Detect Port Trunk Costs
Port Speed Port Cost
10 Mbps 20,000
100 Mbps 20,000
1000 Mbps 2,000