120Step Command Remarks3. Enable the loop guardfunction for the ports. stp loop-protection By default, loop guard isdisabled.Configuring port role restrictionCAUTION:Use this feature with caution, because enabling port role restriction on a port might affect the connectivityof the spanning tree topology.The bridge ID change of a device in the user access network might cause a change to the spanning treetopology in the core network. To avoid this problem, you can enable port role restriction on a port. Withthis feature enabled, when the port receives a superior BPDU, it becomes an alternate port rather than aroot port.Make this configuration on the port that connects to the user access network.To configure port role restriction:Step Command Remarks1. Enter system view. system-view N/A2. Enter Layer 2 Ethernet oraggregate interface view.interface interface-typeinterface-number N/A3. Enable port role restriction. stp role-restriction By default, port role restriction isdisabled.Configuring TC-BPDU transmission restrictionCAUTION:Enabling TC-BPDU transmission restriction on a port might cause the previous forwarding address table tofail to be updated when the topology changes.The topology change to the user access network might cause the forwarding address changes to the corenetwork. When the user access network topology is unstable, the user access network might affect thecore network. To avoid this problem, you can enable TC-BPDU transmission restriction on a port. Withthis feature enabled, when the port receives a TC-BPDU, it does not forward the TC-BPDU to other ports.Make this configuration on the port that connects to the user access network.To configure TC-BPDU transmission restriction:Step Command Remarks1. Enter system view. system-view N/A2. Enter Layer 2 Ethernet oraggregate interface view.interface interface-typeinterface-number N/A3. Enable TC-BPDU transmissionrestriction. stp tc-restriction By default, TC-BPDU transmissionrestriction is disabled.
