User Manual

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GS728TS, GS728TPS, GS752TS, and GS752TPS Gigabit Smart Switches
CST Configuration
Use the Spanning Tree CST Configuration page to configure Common Spanning Tree (CST)
and Internal Spanning Tree on the switch.
To display the Spanning Tree CST Configuration page, click Switching > STP > Advanced >
CST Configuration.
To configure CST settings:
1. Specify values for CST in the appropriate fields:
• Bridge Priority. 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. Specifies the bridge priority value for the Common and Internal
Spanning Tree (CST). The valid range is 0–61440. 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 the priority is
attempted to be set to any value between 0 and 4095, it will be set to 0. The default
priority is 32768.
• Bridge Max Age (secs). Specifies 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 valid range is 6–40, and
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 default value is 20.
• Bridge Hello Time (secs). 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 (secs). Specifies the switch forward delay time, which
indicates the amount of time in seconds a bridge remains in a listening and learning