Multiple Instance Spanning-Tree Operation

Configuring MSTP

7. To review your pending configuration, use the show spanning-tree pending command (see page 4-57).

8. To exchange the currently active MSTP configuration with the pending

MSTP configuration, use the spanning-tree pending apply command.

 

MSTP VLAN Configuration Enhancement

 

The MSTP VLAN configuration enhancement allows you to preconfigure an

 

MSTP regional topology and ensure that the same VLAN ID-to-MSTI assign-

 

ments exist on each MSTP switch in the region.

 

 

C a u t i o n

When this software version is installed, the prior VLAN ID-to-MSTI mappings

 

do not change. However, this enhancement is not backward-compatible. If you

 

install a software version prior to this version, and you have configured MSTI

 

entries instances mapped to VLANs, they will be removed from the configu-

 

ration file when booting to the prior version of software. You must do one of

 

the following if you want to install or reload a prior version of the software:

 

1.

Remove all MSTP mappings from the config file and then reconfigure the

 

 

instance mapping after you are running the desired software version.

 

2.

Save your current configuration file before updating your software to a

 

 

new version. If you later reload this older version of the software, you

 

 

can used this configuration file when you reload the older version. See

 

 

“How to Save Your Current Configuration” on page 4-47.

 

 

 

The default behavior of the spanning-tree instance vlan command changes so that, before a static VLAN is configured or a dynamic VLAN is learned on the switch, you can preconfigure its VLAN ID-to-MSTI mapping. Later, when the VLAN is created, it is automatically assigned to the MSTI to which you had previously mapped it.

By supporting preconfigured VLAN ID-to-MSTI topologies, the VLAN Configuration enhancement provides the following benefits:

■Scalability: In a network design in which you plan to use a large number of VLANs, you can preconfigure identical VLAN ID-to-MSTI mappings on all switches in a single, campus-wide MST region, regardless of the specific VLANs that you later configure on each switch. After the initial VLAN ID-to-MSTI mapping, you can decide on the exact VLANs that you need on each switch.

All switches in a region must be configured with the same VLAN ID-to- MSTI mappings and the same MSTP configuration identifiers (region name and revision number).

4-42