User Manual

Configuring Switching Information
159
M6100 Web Management User Guide
CST Port Configuration
Use the Spanning Tree CST Port Configuration page to configure the Common Spanning
Tree (CST) and Internal Spanning Tree on a specific port on the switch.
A port can become Diagnostically Disabled (D-Disable) when DOT1S experiences a severe
error condition.
The most common cause is when the DOT1S software experiences BPDU
flooding. The flooding criteria is such that DOT1S receives more than 15 BPDUs in a
3-second interval. The other causes for DOT1S D-Disable are extremely rare.
To display the Spanning Tree CST Port Configuration page, click Switching > STP >
Advanced
 CST Port Configuration.
To configure CST port settings:
1. Interface - One of the physical or port channel interfaces associated with VLANs
associated with the CST
.
2. Use Port Priority to specify the priority for a particular port within the CST
. The port priority
is set in multiples of 16. For example if the priority is attempted to be set to any value
between 0 and 15, it will be set to 0. If it is tried to be set to any value between 16 and
(2*16-1) it will be set to 16 and so on. The default value is 128.
3. Use Admin Edge Port to specify if the specified port is an Edge Port within the CIST
. Use
the menu to select Disable or Enable. The default value is Disable.
4. Use Port Path Cost to set the Path Cost to a new value for the specified port in the
common and internal spanning tree. It takes a value in the range of 1 to 200000000.
The
default is 0.
5. Use External Port Path Cost to set the External Path Cost to a new value for the specified
port in the spanning tree. It takes a value in the range of 1 to 200000000.
The default is 0.
6. Use BPDU Filter to configure the BPDU Filter
, which filters the BPDU traffic on this port
when STP is enabled on this port. The possible values are Enable or Disable. The default
value is Disable.
Forward Delay(secs) Derived value of the Root Port Bridge Forward Delay
parameter.
Hold Time(secs) Minimum time between transmission of
Configuration BPDUs.
CST Regional Root Priority and base MAC address of the CST Regional
Root.
CST Path Cost
Path Cost to the CST tree Regional Root.
Field Description