User Manual

Configure Switching Information
235
M6100, M5300, and M7100 Series Managed Switches
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. 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 is set to 0. The default priority
is 32768.
• Bridge Max Age (secs). 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). 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). 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 seconds.
• Spanning Tree Maximum Hops. The maximum number of bridge hops the
information for a particular CST instance can travel before being discarded. The valid
range is 6–40. The default is 20 hops.
• Spanning Tree Tx Hold Count. Configures the maximum number of bpdus the bridge
is allowed to send within the hello time window. The valid range is 1–10. The default
value is 6.
9. Click the Apply button.
The updated configuration is sent to the switch. Configuration changes take effect
immediately.
To refresh the screen with the latest information on the switch, click the Update button.
The following table describes the CST Status information that is displayed.
Table 87. STP Advanced CST Configuration
Field Description
Bridge identifier The bridge identifier for the CST. It is made up using the bridge priority
and the base MAC address of the bridge.
Time since topology change The time in seconds since the topology of the CST last changed.
Topology change count Number of times topology changed for the CST.