3com 4210 ユーザーズマニュアル

The Switch 5500 supports the Multiple Spanning Tree Protocol (MSTP), which 
allows you to map one or multiple VLANs to a multiple spanning tree instance 
(MSTI). Note that one VLAN can be mapped to only one MSTI. With MSTP, the 
packets of a specific VLAN are transmitted in the MSTI to which the VLAN is 
mapped, thus saving overhead and reducing resource utilization.

Figure 22   Network diagram for MSTP configuration

Configure MSTP in the network shown in Figure 22 to enable packets of different 
VLANs to travel along different MSTIs. Do the following:

■

Assign all switches in the network to the same MST region.

■

Enable packets of VLAN 10, VLAN 30, VLAN 40, and VLAN 20 to travel along 
MSTI 1, MSTI 3, MSTI 4, and MSTI 0 respectively.

In this network, Switch A and Switch B are operating at the distribution layer; 
Switch C and Switch D are operating at the access layer. VLAN 10 and VLAN 30 
are terminated at the distribution layer and VLAN 40 is terminated at the access 
layer. Configure Switch A as the root bridge of MSTI 1, Switch B as the root bridge 
of MSTI 3, and Switch C as the root bridge of MSTI 4.

VLAN 

MSTI 

VLAN 10 

MSTI 1 

VLAN 20 

MSTI 0 

VLAN 30 

MSTI 3 

VLAN 40 

MSTI 4

Permit

˖all VLAN

Permit

˖

VLAN20

ˈ30

Permit

˖

VLAN10

ˈ20

Permit

˖VLAN20, 40

Permit

˖

VLAN20

ˈ30

Permit

˖

VLAN10

ˈ20

Switch A

Switch B

Switch C

Switch D