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GS752TP, GS728TP, and GS728TPP Gigabit Smart Switches
CST Configuration
To configure Common Spanning Tree (CST) and Internal Spanning Tree on the switch, use
the CST Configuration screen.
To configure CST settings:
1. Select Switching
STP Advanced CST Configuration.
The following screen displays:
2. Specify values for CST in the following fields:
• Bridge Priority. Specify the bridge priority value for the Common and Internal
Spanning
Tree (CST). When switches or bridges are running STP, each is assigned a
priority. After exchanging BPDUs, the switch with the lowest priority value becomes
the root bridge. The bridge priority is a multiple of 4096. If you specify a priority that is
not a multiple of 4096, the priority is automatically set to the next lowest priority that is
a multiple of 4096. For example, if you set the priority to any value from 0 through
4095, it is set to 0. The valid range is 0–61440. The default priority is 32768.
• Bridge Max
Age (Sec). Specify the bridge maximum age time for the Common and
Internal Spanning Tree (CST), which indicates the amount of time in seconds a bridge
waits before implementing a topological change. The value must be less than or equal
to (2 * bridge forward delay) – 1 and greater than or equal to 2 * (bridge hello time +1).
The valid range is 6–40, and the default value is 20.
• Bridge Hello T
ime (Sec). Specifies the switch hello time for the Common and
Internal Spanning Tree (CST), which indicates the amount of time in seconds a root
bridge waits between configuration messages. The value is fixed at 2 seconds.
• Bridge Forward Delay (Sec). Specify the switch forward delay time, which indicates
the amount of time in seconds a bridge remains in a listening and learning state
before forwarding packets.
The value must be greater or equal to (bridge max age / 2)
+ 1. The valid range is 4–30 seconds. The default value is 15.