3com 8807 User Guide

152

HAPTER

17: MSTP R

EGION

CONFIGURATION

Typical MSTP
Configuration
Example

Network requirements

MSTP provides different forwarding paths for packets of different VLANs. The
configurations are as follows: all the switches in the network belong to the same
MST region, packets of VLAN 10 travels along instance 1, packets of VLAN 30
travels along instance 3, packets of VLAN 40 travels along instance 4, and that of
VLAN 20 travels along instance 0.

In the following network diagram, Switch A and Switch B are devices of the
convergence layer, Switch C and Switch D are devices of the access layer. VLAN 10
and 30 function at the distribution and access layers, and VLAN 40 functions at
the access layer only. So the root of instance 1 can be configured as Switch A, root
of instance 3 can be Switch B, and root of instance 4 can be Switch C.

Network diagram

Figure 31 Network diagram for MSTP configuration

The explanations on the above figure which goes like "permit: XXXX" means that
packets of these VLANs are permitted to pass.

Enable debugging of the state machine
for port state transition

undo debugging stp state-machine pst

Enable debugging of the topology
change state machine

debugging stp state-machine tcm

Disable debugging of the topology
change state machine

undo debugging stp state-machine tcm

Enable debugging of the state machine
for port protocol transition

debugging stp state-machine ppm

Disable debugging of the state machine
for port protocol transition

undo debugging stp state-machine ppm

Enable debugging of the port transport
state machine

debugging stp state-machine ptx

Disable debugging of the port transport
state machine

undo debugging stp state-machine ptx

Enable debugging of the state machine
for topology change protection

debugging stp state-machine tcpm

Disable debugging of the state machine
for topology change protection

undo debugging stp state-machine tcpm

Table 136 Display and debug MSTP

Operation Command

Switch A

Switch C

Switch B

Switch D

Permit :
VLAN 10, 20

Permit :
VLAN 20, 30

Permit :all VLAN

Permit :VLAN 20, 40