Allied Telesis AT-S62 - Manual (Page 256)

Chapter 20: STP, RSTP, and MSTP
Section IV: Spanning Tree Protocols 256
6 - Bridge Identifier
The MAC address of the bridge. The bridge identifier is used as a
tie breaker in the selection of the root bridge when two or more
bridges have the same bridge priority value. This value cannot be
changed.
3. After you have made your changes, click Apply.
4. To adjust RSTP port settings, click on the port in the switch image and
click Modify. You can select more than one port at a time.
The RSTP Port Settings window is shown in Figure 95.
Figure 95 RSTP Port Settings Window
5. Adjust the settings as desired. The parameters are described below.
1 - Port Priority
This parameter is used as a tie breaker when two or more ports are
determined to have equal costs to the root bridge. The range is 0
to 240 in increments of 16. The default value is 8 (priority value
128). For a list of the increments, refer to Table 7, Port Priority
Value Increments on page 252.
2 - Port Cost
The spanning tree algorithm uses the cost parameter to decide
which port provides the lowest cost path to the root bridge for
that LAN. The range is 0 to 20,000,000. The default setting is
Automatic detect, which sets port cost depending on the speed of
the port. Table 10 lists the RSTP port costs with Auto-Detect when
the port is not part of a port trunk.
Table 10 RSTP Auto-Detect Port Costs
Port Speed Port Cost
10 Mbps 2,000,000