If user networks are connected through Layer-2 devices and do not forward data through Layer-3 routing, you can configure a MAC address table based on Layer-2 interfaces and VLANs for data forwarding. Thus, user networks can communicate with each other.
After the network topology changes, dynamic MAC address entries are not automatically updated in time. As a result, a device cannot learn new MAC addresses and thus user traffic cannot be normally forwarded. To address this problem, you need to configure the aging time of MAC address entries.