On S series modular switches, after a switchover in the CSS, why the system MAC address becomes a single MAC address from multiple MAC addresses


After a CSS is configured to use MAC addresses of the master switch, the system synchronizes the MAC addresses and number of MAC addresses to the candidate standby MPU on the master switch and the system standby MPU of the cluster. Then the system standby MPU synchronizes them to the candidate standby MPU on the standby switch. If the master switch has multiple MAC addresses and the standby switch has a single MAC address, the CSS has multiple MAC addresses.
In V200R001, the CSS retains the original cluster MAC address after a switchover, but the number of MAC addresses is equal to the number of MAC addresses on the new master switch. Because the original standby switch has only one MAC address, the CSS has a single MAC address after the switchover. As a result, some services in the CSS may be interrupted or the CSS may be disconnected from the operation terminal or network management system. To prevent this problem, load the latest patch on the V200R001 system software before triggering a switchover. If a switchover has occurred, restart the CSS after loading the patch.
You can run the display css system-mac command to check the CSS MAC address.

Other related questions:
How to determine the MAC address of a CSS composed of S series modular switches
The MAC address of the master switch is used as the system MAC address of the CSS when the CSS is set up. If you restart the CSS or remove and reinstall another MPU, the system MAC address may change, resulting in service interruptions. To prevent this problem, run the set css system-mac chassis chassis-id command to set the system MAC address to the MAC address of a member switch, ensuring consistency of the system MAC address.

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.

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.

Why Is one MAC address learned in multiple VLANs on S series switch
On S series switches (except S1700), MAC addresses are learned based on MAC addresses+VLANs. If multiple VLANs receive packets with the same MAC address, these VLANs will learn the same MAC address.

How to add a MAC address for MAC address authentication on S series switches
For S series switches (except the S1700), if a new MAC address entry is generated after MAC address authentication is configured on an interface, MAC address authentication will be performed for the MAC address. You can perform the following operations to add a MAC address for MAC address authentication. [HUAWEI] interface Vlanif 10 [HUAWEI-Vlanif10] mac-authen permit mac-address 1111-1111-1111 mask 24

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