3Com Switch 7750 Series
Command Reference Guide – MSTP Chapter 1 MSTP Configuration Commands
1-39
recommended to set the network diameter and leave the Forward delay and Max age
parameters being automatically determined by the network diameter you set.
Caution:
z You can configure only one root bridge for a spanning tree instance and can
configure one or more secondary root bridges for a spanning tree instance.
Configuring multiple root bridges for a spanning tree instance causes unpredictable
spanning tree computing results.
z Once a switch is configured as the root bridge or a secondary root bridge, its priority
cannot be modified.
Example
# Configure the current switch as the root bridge of spanning tree instance 1, setting the
network diameter of the switched network to 4, and the Hello time to 500 centiseconds.
<3Com> system-view
System View: return to User View with Ctrl+Z.
[3Com] stp instance 1 root primary bridge-diameter 4 hello-time 500
1.1.37 stp root secondary Syntax
stp [ instance instance-id ] root secondary [ bridge-diameter bridgenum ]
[ hello-time centi-seconds ]
undo stp [ instance instance-id ] root
View
System view
Parameter
instance-id: Spanning tree instance ID ranging from 0 to 16. A value of 0 specifies the
CIST.
bridgenum: Network diameter of the specified spanning tree. This argument ranges
from 2 to 7 and defaults to 7.
centi-seconds: Hello time in centiseconds of the specified spanning tree. This argument
ranges from 100 to 1,000 and defaults to 200.