mac

Commands for MSTP
236
Function: Set the port is root port, “no spanning-tree rootguard” command sets the
port is non-root port.
Parameter: None.
Command mode: Port Mode.
Default: Port is non-root port.
Usage Guide: The command is used in Port 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: Set the port 1 is root port.
Switch(Config-If-Ethernet1/1)#spanning-tree rootguard
17.1.30 spanning-tree tcflush (Global mode)
Command: spanning-tree tcflush {enable| disable| protect}
no spanning-tree tcflush
Function: Configure the spanning-tree flush mode once the topology changes. “no
spanning-tree tcflush” restores to default setting.
Parameter: enable: The spanning-tree flush once the topology changes.
disable: The spanning tree don’t flush when the topology changes.
protect: the spanning-tree flush not more than one time every ten seconds.
Command mode: Global mode
Default: Enable
Usage Guide: According to MSTP, when topology changes, the port that send change
message clears MAC/ARP table (FLUSH). In fact it is not needed for some network
environment to do FLUSH with every topology change. At the same time, as a method to
avoid network assault, we allow the network administrator to configure FLUSH mode by
the command
Note: For the complicated network, especially need to switch from one spanning tree
branch to another rapidly, the disable mode is not recommended.
Example: Configure the spanning-tree flush mode once the topology changes is not
flush to TC.
Switch(config)#spanning-tree tcflush disable
Switch(config)#