Default Spanning-Tree Configuration
The default Spanning Tree parameters are as follows:
Feature | Default Value |
Enable state | STP enabled for all ports |
Port priority | 128 |
Port cost | 100 |
Bridge Priority | 32,768 |
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User-Changeable STP Parameters
The factory default setting should cover the majority of installations. However, it is advisable to keep the default settings as set at the factory; unless it is absolutely necessary. The user changeable parameters in the Switch are as follows:
•Hello Time
The Hello Time can be from 1 to 10 seconds. This is the interval between two transmissions of BPDU packets sent by the Root Bridge to tell all other Switches that it is indeed the Root Bridge. If you set a Hello Time for your Switch, and it is not the Root Bridge, the set Hello Time will be used if and when your Switch becomes the Root Bridge. The Hello Time cannot be longer than the Max. Age. Otherwise, a configuration error will occur.
•Max Age
The Maximum Age Timer can be from 6 to 40 seconds. At the end of the Max. Age, if a BPDU has still not been received from the Root Bridge, the Switch will start sending its own BPDU to all other switches for permission to become the Root Bridge. If it turns out the Switch has the lowest Bridge Identifier, it will become the Root Bridge.
•Forward Delay
The Forward Delay can be from 4 to 30 seconds. This is the time any port on the Switch spends in the listening state while moving from the blocking state to the forwarding state.
•Priority
A Priority for the switch can be set from 0 to 65535. 0 is equal to the highest Priority.
Observe the following formulas when setting the above parameters:
-Max. Age = 2 x (Forward Delay - 1 second)
-Max. Age = 2 x (Hello Time + 1 second)
-Port Priority A Port Priority can be from 0 to 255. The lower the number, the greater the probability the port will be chosen as the Root Port.
-Port Cost A Port Cost can be set from 1 to 65535. The lower the number, the greater the probability the port will be chosen to forward packets.
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