User's Manual

Table Of Contents
232
Users Manual of CS-6306R
spanning-tree mstp instanceinstance-id
vlanvlan-list
Maps VLAN to MSTI.
instance-id represents the instance number of the
spanning tree, meaning an MSTI. It ranges from 1
to 15.
vlan-list means the VLAN list that is mapped to the
spanning tree. It ranges from 1 to 4094.
instance-id is an independent value representing a
spanning tree instance.
vlan-list can represent a group of VLANs, such
as ”1,2,3”, ”1-5” and “1,2,5-10”.
no spanning-tree mstp instanceinstance-id
Cancels the VLAN mapping of MSTI and disables
the spanning tree instance.
instance-id represents the instance number of the
spanning tree, meaning an MSTI. It ranges from 1
to 15.
Run the following command to check the configuration of the MSTP area:
Command Purpose
show spanning-tree mstp region Displays the configuration of the MSTP area.
19.2.3.4 Configuring Network Root
In MSTP, each spanning tree instance has a bridge ID, containing the priority value and MAC address of the
switch. During the establishment of spanning tree topology, the switch with comparatively small bridge ID is
selected as the network root.
MSTP can set the switch to the network switch through configuration. You can run the command
Spanning-tree mstpSpanning-tree mstpinstance-idrootroot to modify the priority value of the switch in a
spanning tree instance from the default value to a sufficiently small value, ensuring the switch turns to be the
root in the spanning tree instance.
In general, after the previous command is executed, the protocol automatically check the bridge ID of the
current network root and then sets the priority field of the bridge ID to 24576 when the value 24576 ensures
that the current switch becomes the root of the spanning tree.
If the network root’s priority value is smaller than the value 24576, MSTP automatically sets the spanning
tree's priority of the current bridge to a value that is 4096 smaller than the priority value of the root. Note that
the number 4096 is a step length of network priority value.
When setting the root, you can run the diameter subcommand to the network diameter of the spanning tree
network. The keyword is effective only when the spanning tree instance ID is 0. After the network diameter is
set, MSTP automatically calculates proper STP time parameters to ensure the stability of network
convergence. Time parameters include Hello Time, Forward Delay and Maximum Age. The subcommand
Hello-time can be used to set a new hello time to replace the default settings.
Run the following command to set the switch to the network root: