User Manual

Chapter 20: Spanning Tree, Rapid Spanning Tree, and Multiple Spanning Tree Protocols
276 Section IV: Spanning Tree Protocols
this aging time to test the age of stored configuration messages called
bridge protocol data units (BPDUs). For example, if you use the default
value 20, all bridges delete current configuration messages after 20
seconds. This parameter can be from 6 to 40 seconds.
In selecting a value for maximum age, the following rules must be
observed:
MaxAge must be greater than (2 x (HelloTime + 1))
MaxAge must be less than (2 x (ForwardingDelay - 1))
Note
The aging time for BPDUs is different from the aging time used by
the MAC address table.
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. When you are finished setting the parameters, click Apply.
4. To adjust a port’s STP settings, click on the port in the switch image
and click Modify. You can select more than one port at a time.
The STP Port Settings window is shown in Figure 93.
Figure 93. STP 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 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 8 on
page 277 lists the values and increments. The default value is 128,
which is increment 8.