Chapter 7 Spanning Tree
7.5 Application Example for STP Function
¾ Network Requirements
z Switch A, B, C, D and E all support MSTP function. z A is the central switch.
z B and C are switches in the convergence layer. D, E and F are switches in the access layer. z There are 6 VLANs labeled as VLAN101-VLAN106 in the network.
z All switches run MSTP and belong to the same MST region.
z The data in VLAN101, 103 and 105 are transmitted in the STP with B as the root bridge. The data in VLAN102, 104 and 106 are transmitted in the STP with C as the root bridge.
¾ Configuration Procedure z Configure Switch A:
Step Operation Description
1 Configure ports On VLAN→802.1Q VLAN page, configure the link type of the related ports as Trunk, and add the ports to VLAN101-VLAN106. The detailed instructions can be found in the section 802.1Q VLAN.
2 Enable STP function On Spanning Tree→STP Config→STP Config page, enable STP function and select MSTP version.
On Spanning Tree→STP Config→Port Config page, enable MSTP function for the port.
3 Configure the region name and the revision of MST region
On Spanning Tree→MSTP Instance→Region Config page, configure the region as TP-LINK and keep the default revision setting.
4 Configure VLAN-to-Instance mapping table of the MST region
On Spanning Tree→MSTP Instance→Instance Config page, configure VLAN-to-Instance mapping table. Map VLAN 101, 103 and 105 to Instance 1; map VLAN 102, 104 and 106 to Instance 2.
z Configure Switch B:
Step Operation Description
1 Configure ports On VLAN→802.1Q VLAN page, configure the link type of the related ports as Trunk, and add the ports to VLAN101-VLAN106. The detailed instructions can be found in the section 802.1Q VLAN.
2 Enable STP function On Spanning Tree→STP Config→STP Config page, enable STP function and select MSTP version.
On Spanning Tree→STP Config→Port Config page, enable MSTP function for the port.
3 Configure the region name and the revision of MST region
On Spanning Tree→MSTP Instance→Region Config page, configure the region as TP-LINK and keep the default revision setting.
4 Configure VLAN-to-Instance mapping table of the MST region
On Spanning Tree→MSTP Instance→Instance Config page, configure VLAN-to-Instance mapping table. Map VLAN 101, 103 and 105 to Instance 1; map VLAN 102, 104 and 106 to Instance 2.
5 Configure switch B as the root bridge of Instance 1
On Spanning Tree→MSTP Instance→Instance Config page, configure the priority of Instance 1 to be 0.
6 Configure switch B as the designated bridge of Instance 2
On Spanning Tree→MSTP Instance→Instance Config page, configure the priority of Instance 2 to be 4096.
z Configure Switch C:
Step Operation Description
1 Configure ports On VLAN→802.1Q VLAN page, configure the link type of the related ports as Trunk, and add the ports to VLAN101-VLAN106. The detailed instructions can be found in the section 802.1Q VLAN.
2 Enable STP function On Spanning Tree→STP Config→STP Config
page, enable STP function and select MSTP version. On Spanning Tree→STP Config→Port Config
page, enable MSTP function for the port. 3 Configure the region name and
the revision of MST region
On Spanning Tree→MSTP Instance→Region Config page, configure the region as TP-LINK and keep the default revision setting.
4 Configure VLAN-to-Instance mapping table of the MST region
On Spanning Tree→MSTP Instance→Instance Config page, configure VLAN-to-Instance mapping table. Map VLAN101, 103 and 105 to Instance 1; map VLAN102, 104 and 106 to Instance 2.
5 Configure switch C as the root bridge of Instance 1
On Spanning Tree→MSTP Instance→Instance Config page, configure the priority of Instance 1 to be 4096.
6 Configure switch C as the root bridge of Instance 2
On Spanning Tree→MSTP Instance→Instance Config page, configure the priority of Instance 2 to be 0.
z Configure Switch D:
Step Operation Description
1 Configure ports On VLAN→802.1Q VLAN page, configure the link type of the related ports as Trunk, and add the ports to VLAN101-VLAN106. The detailed instructions can be found in the section 802.1Q VLAN.
2 Enable STP function On Spanning Tree→STP Config→STP Config
page, enable STP function and select MSTP version. On Spanning Tree→STP Config→Port Config
page, enable MSTP function for the port. 3 Configure the region name and
the revision of MST region
On Spanning Tree→MSTP Instance→Region Config page, configure the region as TP-LINK and keep the default revision setting.
4 Configure VLAN-to-Instance mapping table of the MST region
On Spanning Tree→MSTP Instance→Instance Config page, configure VLAN-to-Instance mapping table. Map VLAN101, 103 and 105 to Instance 1; map VLAN102, 104 and 106 to Instance 2.
¾ The topology diagram of the two instances after the topology is stable
z For Instance 1 (VLAN101, 103 and 105), the red paths in the following figure are connected links; the gray paths are the blocked links.
z For Instance 2 (VLAN102, 104 and 106), the blue paths in the following figure are connected links; the gray paths are the blocked links.
¾ Suggestion for Configuration
z Enable TC Protect function for all the ports of switches. z Enable Root Protect function for all the ports of root bridges. z Enable Loop Protect function for the non-edge ports.
Enable BPDU Protect function or BPDU Filter function for the edge ports which are connected to the PC and server.