66
Configuration restrictions and guidelines
•
The configuration of MST region–related parameters, especially the VLAN-to-instance mapping
table, will result in a new spanning tree calculation. To reduce the possibility of topology
instability, the MST region configuration takes effect only after you activate it by using the
active
region-configuration
command, or enable a spanning tree protocol by using the
stp enable
command in the case that the spanning tree protocol is disabled.
•
The device in PVST mode automatically maps VLANs to MSTIs, and supports more MSTIs
than in MSTP mode. When you change the spanning tree mode from PVST to MSTP,
exceeding VLAN-to-instance mappings (arranged in ascending order of MSTI IDs) are silently
deleted and cannot be recovered even if you change the spanning tree mode back. To prevent
loss of mappings, do not manually configure VLAN-to-instance mappings in PVST mode.
Configuration procedure
To configure an MST region:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter MST region view.
stp region-configuration
N/A
3.
Configure the MST
region name.
region-name
name
Optional.
The MST region name is the MAC
address by default.
4.
Configure the
VLAN-to-instance
mapping table.
•
instance
instance-id
vlan
vlan-list
•
vlan-mapping modulo
modulo
Optional.
Use either command.
All VLANs in an MST region are mapped
to the CIST (or MSTI 0) by default.
5.
Configure the MSTP
revision level of the
MST region.
revision-level
level
Optional.
0 by default.
6.
Display the MST region
configurations that are
not activated yet.
check region-configuration
Optional.
7.
Activate MST region
configuration manually.
active region-configuration
N/A
8.
Display the activated
configuration
information of the MST
region.
display stp
region-configuration
[
|
{
begin
|
exclude
|
include
}
regular-expression
]
Optional.
Available in any view
Configuring the root bridge or a secondary root
bridge
You can have MSTP determine the root bridge of a spanning tree through MSTP calculation, or you
can specify the current device as the root bridge or as a secondary root bridge using the commands
that the system provides.