How to view and change MAC addresses of BPDUs

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Run the display bpdu mac-address command to query the current BPDU MAC addresses. By default, all multicast MAC addresses in the segment from 0180-c200-0010 to 0180-c200-002f are BPDU MAC addresses, and 0100-0ccc-cccd is also a BPDU MAC address.

Run the bpdu mac-address mac-address command to specify an MAC address to be a BPDU MAC address.

Example: bpdu mac-address 0100-0ccc-cccc

Other related questions:
Why is the MAC address of a BPDU replaced with a multicast MAC address in BPDU tunneling on S series switches
On S series (except the S1700) and E series switches, the MAC address of a BPDU from a user-side device is replaced so that the BPDU can be transparently transmitted across the ISP network. Otherwise, the BPDU will be processed by the ISP network as a protocol packet and cannot reach the remote user-side device, and network flapping will occur.

Why is the MAC address of a BPDU replaced by a multicast MAC address in BPDU tunneling
The MAC address of a BPDU from a user-side device is replaced so that the BPDU can be transparently transmitted across the carrier network. Otherwise, the BPDU will be processed by the carrier network as a protocol packet and cannot reach the remote user-side device, and network flapping will occur. According to the implementation of BPDU tunneling, the MAC address of a BPDU can be replaced by a multicast, broadcast, or unicast address. The reason why a case-shaped switch selects a multicast MAC address is as follows: If the MAC address of a BPDU is replaced by a broadcast MAC address, the BPDU may be attacked when being transparently transmitted because a broadcast packet is vulnerable to attacks. If the MAC address of a BPDU is replaced by a unicast MAC address, the switch may be unable to learn the source MAC address of the BPDU when forwarding it and still processes it as a broadcast packet.

How do I change the MAC address of an AR
To change the MAC address of an AR, use the following method. Run the set system-mac command in the diagnostic view. For example, # Change the default MAC address to 00e0-0987-7890. [Huawei] diagnose [Huawei-diagnose] set system-mac default 00e0-0987-7890 Info: The public mac-address set pass. Note: A MAC address is globally unique. Do not change the MAC address of an AR in normal situations. When configuring a MAC address, note the following points: - The MAC address cannot be all 0s or all 1s. - The multicast MAC address cannot be configured. - If a device supports multiple MAC addresses, the last four bits of the MAC address must be all 0s.

Change the system MAC address on S series switch
Generally, it is not allowed to change the system MAC address on S series switches (except S1700). If it is required to change the system MAC address, run the set system-mac current command on modular switches and then restart the switch to make the modification take effect. Fixed switches do not support the modification of the system MAC address.

How do I view the MAC address of the IAD
You can view the MAC address in either of the following ways: Log in to the web management system, and choose Basic Configuration > Network Parameter. Log in to the CLI, and run the enable and configure terminal commands in sequence to enter the global configuration mode. Then run the display mac-address command.

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