Specifications

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DCS-3950 series Ethernet switch manual
Function: Set the bridge priority for the specified instance; The command ‘no
spanning-tree mst <instance-id> priority’ restores the default setting.
Parameters: <instance-id> sets instance ID. The valid range is from 0 to 48;
<bridge-priority> sets the switch priority. The valid range is from 0 to 61440. The value
should be the multiples of 4096, such as 0, 4096, 8192…61440.
Command mode: Global Mode
Default: The default bridge priority is 32768.
Usage Guide: By setting the bridge priority, users can change the bridge ID for the
specified instance. And the bridge ID can influence the elections of root bridge and
designated port for the specified instance.
Example: Set the priority for Instance 2 to 4096.
Switch(Config)#spanning-tree mst 2 priority 4096
10.2.2.18 spanning-tree mst rootguard
Command: spanning-tree mst <instance-id> rootguard
no spanning-tree mst <instance-id> rootguard
Function: Enable the rootguard function for specified instance, the rootguard function
forbid the port to be MSTP root port. ‘no spanning-tree mst <instance-id> rootguard’
disable the rootguard function.
Parameter:<instance-id>：MSTP instance ID.
Command mode: Interface Mode.
Default: Disable rootguard function.
Usage Guide: The command is used in interface mode ,if the port is configured to be a
rootguand port , it is forbidden to be a MSTP root port. If superior BPDU packet is
received from a rootguard port, MSTP did not recalculate spanning-tree, and just set the
status of the port to be root_inconsistent(blocked).If no superior BPDU packet is received
from a blocked rootguard port, the port status will restore to be forwarding. The rootguard
function can maintain a relative stable spanning-tree topology when a new switch is
added to the network.
Example: Enable rootguard function for port 0/0/2 in instance 0.
Switch(Config)#interface ethernet 0/0/2
Switch(Config-Ethernet-0/0/2)#spanning-tree mst 0 rootguard
10.2.2.19 spanning-tree portfast
Command: spanning-tree portfast
no spanning-tree portfast
Function: Set the current port as boundary port; The command ‘no spanning-tree portfast’
sets the current port as non-boundary port.
Parameters: bpdufilter: Set the boundary port mode as BPDU filter; bpduguard: Set the
boundary port mode as BPDU guard; default: Set the boundary port mode as default.
Command mode: Interface Mode
Default: All the ports are non-boundary ports.