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Catalyst 6500 Series Switch Command Reference—Release8.4
OL-6244-01
Chapter2 Catalyst 6500 Series Switch and ROM Monitor Commands
set spantree root
set spantree root
To set the primary or secondary root for specific VLANs, all VLANs of the switch, or an instance, use
the set spantree root command.
set spantree root [secondary] [vlans] [dia network_diameter] [hello hello_time]
set spantree root [secondary] mistp-instance instance [dia network_diameter]
[hello hello_time]
set spantree root [secondary] mst instance [dia network_diameter] [hello hello_time]
Syntax Description
Defaults If you do not specify the secondary keyword, the default is to make the switch the primary root.
The default value of the network diameter is 7.
If you do not specify the hello_time value, the current value of hello_time is calculated from the network
diameter.
Command Types Switch command.
Command Modes Privileged.
Usage Guidelines If you do not specify a VLAN number, VLAN 1 is assumed.
This command is not supported by the NAM.
This command is run on backbone or distribution switches.
You can run the secondary root many times to create backup switches in case of a root failure.
The set spantree root secondary bridge priority value is 16384, except when MAC reduction or MISTP
are enabled, then the value is 28672.
The set spantree root bridge priority value is 16384, except when MAC reduction or MISTP are
enabled, then the value is 24576.
secondary (Optional) Designates this switch as a secondary root, should the primary root
fail.
vlans (Optional) Number of the VLAN; valid values are from 1 to 4094.
dia network_diameter (Optional) Specifies the maximum number of bridges between any two points
of end stations; valid values are from 1 through 7.
hello hello_time (Optional) Specifies in seconds, the duration between the generation of
configuration messages by the root switch.
mistp-instance
instance Specifies the instance number; valid values are from 0 to 4094.
mst
instance Specifies an MST instance; valid values are from 0 to 4094.