2.5.2 - Force10 Networks

The following commands influence which switch becomes the root bridge and the role of a port in the
spanning tree:
Command Syntax Command Mode Purpose
spanning-tree msti {0 {cost
1-200000000 | external-cost
1-200000000 | 0-240} | 1-63 {cost
1-200000000 | priority 0-240}}
spanning-tree msti priority mstid
0–61440
Interface Config To influence the role of the selected port in the
spanning tree:
• Lowering the cost value reduces the path
cost of the selected port, thereby increasing
the likelihood that it will be selected as the
root port.
• Lowering the priority value reduces the port
priority of the selected port, thereby
increasing the likelihood that its paired port
will be selected as the root port.
Global Config Influence the selection of the root bridge by
setting the bridge priority.
The instance mstid is a number in the range
0-63 that corresponds to the desired existing
multiple spanning tree instance.
0–61440 is the priority value, representing a
range of 0 to 61440, in increments of 4096.
Changing Spanning Tree Global Parameters
SFTOS has the following STP global operational parameters that you can change from their defaults.
Command Syntax Command Mode Purpose
[no] spanning-tree forward-time
4-30
Global Config Set the Bridge Forward Delay forward-time value
for the common and internal spanning tree, with
the value being greater than or equal to "(Bridge
Max Age / 2) + 1".
Range: 4 to 30 seconds
Default: 15 seconds
spanning-tree hello-time 1-10 Global Config Set the Admin Hello Time for the common and
internal spanning tree, with the value being less
than or equal to "(Bridge Max Age / 2) - 1".
Range: 1 to 10 seconds
Default: 2 seconds
162 Spanning Tree