3Com Switch 7750 Configuration Guide Guide

256 CHAPTER 29: MSTP CONFIGURATION
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■ The BPDU Tunnel function can only be enabled on devices with STP enabled.
■ The BPDU Tunnel function can only be enabled on access ports.
■ To enable the BPDU Tunnel function, make sure the links between operator’s
networks are trunk links.
■ If a fabric port exists on a switch, you cannot configure VLAN-VPN function on
any port of the switch.
■ As the VLAN-VPN function is unavailable on ports with 802.1x, GVRP, GMRP,
STP, or NTDP enabled, the BPDU Tunnel function is not applicable to these
ports.
MSTP Displaying and
Debugging
You can verify the above configurations by executing the display commands in
any view.
Execute the reset command in user view to clear MSTP statistics.
MSTP Implementation
Example
Network requirements
Implement MSTP in the network shown in Figure 61 to enable packets of different
VLANs to be forwarded along different spanning tree instances. The detailed
configurations are as follows:
■ All switches in the network belong to the same MST region.
■ Packets of VLAN 10, VLAN 30, VLAN 40, and VLAN 20 are forwarded along
spanning tree instance 1, instance 3, instance 4, and instance 0 respectively.
In this network, Switch A and Switch B operate on the distribution layer; Switch C
and Switch D operate on the access layer. VLAN 10 and VLAN 30 are limited in the
distribution layer and VLAN 40 is limited in the access layer. Switch A and Switch B
are configured as the root bridges of spanning tree instance 1 and spanning tree
instance 3 respectively. Switch C is configured as the root bridge of spanning tree
instance 4.
Enable the VLAN VPN
function for the Ethernet port
vlan-vpn enable
Required
By default, the VLAN VPN
function is disabled on all
ports.
Table 189 Configure the BPDU Tunnel function
Operation Command Description
Tabl e 190 Display and debug MSTP
Operation Command
Display spanning tree-related information
about the current switch
display stp [ instance instance-id ] [
interface interface-list | slot slot-number ] [
brief ]
Display region configuration display stp region-configuration
Clear MSTP-related statistics reset stp [ interface interface-list ]