Can BPDUs be transparently transmitted on a device

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After the bpdu enable command is used on an interface, the interface sends received BPDUs to the CPU for processing. The local device determines whether to process BPDUs of a protocol depending on whether the protocol is enabled. For example, whether STP BPDUSs on an interface are sent to the CPU depends on whether STP has been enabled on the interface using the stp enable command.

After the bpdu disable command is used on an interface, BPDUs received on this interface are discarded by the chip.

To transparently transmit BPDUs on a device, enable Layer 2 protocol transparent transmission on the device interfaces. In V100R005 and later versions, run the l2protocol-tunnel all enable command on an interface to enable Layer 2 protocol transparent transmission. To ensure successful forwarding of packets, configure the default VLAN on the inbound and outbound interfaces of all devices on the forwarding path.

Other related questions:
How can I configure BPDU tunnel to transparently transmit BPDUs
To transparently transmit untagged BPDUs, run the port default vlan command on the inbound and outbound interfaces of the BPDUs. To transparently transmit tagged BPDUs, run the port default vlan command on the outbound interface of the BPDUs.

How to enable a switch to transparently transmit BPDUs that are discarded by default
You can enable a switch to transparently transmit BPDUs in the following modes: 1. Run the bpdu bridge enable command to enable the port bridge function. Then the switch can transparently transmit all BPDUs. 2. Globally specify the group MAC address of BPDU for the inbound and outbound ports of two edge switches on the network, and enable the L2PT transparent transmission function of the protocol for the ports. Incoming BPDUs are replaced with the group MAC address, converted to data packets, and forwarded in the VLAN. Configure the L2PT function in the outbound port to replace the group MAC address with the BPDU MAC address.

How to configure BPDU tunneling on S series switches to transparently transmit BPDUs
To configure S series (except the S1700) and E series switches to transparently transmit BPDUs, perform the following operations: 1. Configure interface-based Layer 2 protocol transparent transmission. (1) Run the l2protocol-tunnel group-mac command in the system view to replace the multicast destination MAC address of Layer 2 protocol packets with a specified multicast MAC address. (2) Run the port default vlan command on the inbound and outbound interfaces to transparently transmit untagged BPDUs. (3) Run the l2protocol-tunnel { all | protocol-type } enable command on the inbound and outbound interfaces to enable interface-based Layer 2 protocol transparent transmission. 2. Configure VLAN-based Layer 2 protocol transparent transmission. (1) Run the l2protocol-tunnel group-mac command in the system view to replace the multicast destination MAC address of Layer 2 protocol packets with a specified multicast MAC address. (2) Run the port link-type hybrid and port hybrid tagged vlan commands on the inbound and outbound interfaces to transparently transmit tagged BPDUs. (3) Run the l2protocol-tunnel { all | protocol-type } vlan command on the inbound and outbound interfaces to enable VLAN-based Layer 2 protocol transparent transmission.

How MSTP BPDUs are transparently transmitted on a VPLS network
For S series switches (except the S1700), MSTP BPDUs are transparently transmitted on a VPLS network using the following methods: 1. Transmitting untagged BPDUs transparently If BPDUs from a Layer 2 network do not carry tags, you need to run the port default vlan vlan-id and stp disable commands on the user-side interface of PE1. After receiving an untagged BPDU from the Layer 2 network, PE1 adds a specific tag to the BPDU and then transparently transmits the BPDU to PE2 over the VPLS network. After receiving the BPDU, PE2 removes the tag and then sends the BPDU to a specific attached user. 2. Transmitting tagged BPDUs transparently If BPDUs from a Layer 2 network carry tags, you need to run the stp bpdu vlan vlan-id command on the user-side interfaces of devices on the Layer 2 network, and run the port trunk allow-pass vlan command on the user-side interface of PE1. After receiving a tagged BPDU from the Layer 2 network, PE1 transparently transmits the BPDU to PE2 over the VPLS network. After receiving the BPDU, PE2 directly sends the BPDU to a specific attached user.

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