User Manual

Configure Switching Information
151
M4100 Series Managed Switch
7. Select Switching > STP > Advanced  CST Configuration.
8. 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. Specify 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 is 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 T
ime (secs). Specifies the bridge 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. The
value must be less than or equal to (Bridge Max Age / 2) – 1. The default Hello time
value is 2.
• Bridge Forward Delay (secs). Specifies the bridge 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 time range is from 4 seconds to 30 seconds. The default value is 15.