236 CHAPTER 23: MSTP C ONFIGURATIONMSTP ConfigurationExampleNetwork requirementsConfigure MSTP so that packets of different VLANs are forwarded along differentspanning trees. The specific configuration requirements are as follows:■ All devices on the network are in the same MST region.■ Packets of VLAN 10 are forwarded along MST region 1, those of VLAN 30 areforwarded along MST instance 3, those of VLAN 40 are forwarded along MSTinstance 4, and those of VLAN 20 are forwarded along MST instance 0.■ Device A and Device B are convergence layer devices, while Device C andDevice D are access layer devices. VLAN 10 and VLAN 30 are terminated on theconvergence layer devices, and VLAN 40 is terminated on the access layerdevices, so the root bridges of MST instance 1 and MST instance 3 are Device Aand Device B respectively, while the root bridge of MST instance 4 is Device C.Network diagramFigure 62 Network diagram for MSTP configurationn “Permit:” beside each link in the figure is followed by the VLANs the packets ofwhich are permitted to pass this link.View the information of port rolecalculation history for the specifiedMSTP instance or all MSTPinstancesdisplay stp [ instanceinstance-id ] historyAvailable in any viewView the statistics of TC/TCNBPDUs sent and received by allports in the specified MSTPinstance or all MSTP instancesdisplay stp [ instanceinstance-id ] tcAvailable in any viewView the status information andstatistics information of MSTPdisplay stp [ instanceinstance-id ] [ interfaceinterface-list ] [ brief ]Available in any viewView the information about MSTregion configuration in effectdisplay stpregion-configurationAvailable in any viewView root bridge information of allMSTP instancesdisplay stp root Available in any viewClear the statistics information ofMSTPreset stp [ interfaceinterface-list ]Available in user viewTo do… Use the command… RemarksDevice A Device BDevice DDevice CPermit:all VLANPermit:VLAN 20,40Permit:VLAN 10,20Permit:VLAN 10,20Permit:VLAN 20,30Permit:VLAN 20,30
