Fill in the MAC address table
As a second layer device, all decisions of the switch are based on the data contained in the L2 header. Based on the source and destination of the MAC address, the switch will determine the forwarding path. One of the tasks of a switch is to establish a MAC address database that matches each switch port with the MAC location of the connected device.
The MAC address database is initially empty, and when the switch receives data, it checks the original MAC address field of the incoming frame. It fills the MAC address database with the source MAC address and the switch port that collects data packets. The switch will eventually have a complete MAC address table, as each connected device needs to send something. Then, this table can be used to intelligently advance frames to the desired position.
Enable MAC filtering and other access control functions
Finally, let's discuss the filtering use cases of network switches. This function specifies that the Switch will never forward frames from the received port. MAC address filters can be used to block connections to specific nodes. You can achieve this by filtering the source and target MAC layer Ethernet addresses on the source (incoming) port of the switch.
According to your network access control requirements, filtering MAC addresses can be unicast, multicast, or broadcast. When a switch needs to flood a frame, the frame is copied and sent to all switch ports (except for the port that obtained it). The host rarely sends frames with the destination address as its own MAC address. This is usually due to an incorrect or malicious situation on the host. When this situation occurs, the switch only discards frames under any circumstances.
The global demand for network switches is constantly increasing to support the era of remote connectivity and the rise of the Internet of Things. IDC's global tracking agency found that the global switch market grew by 7.5% in the third quarter of 2021. This is also due to the increasing adoption of cloud computing, as network switches help coordinate, maintain, and stabilize resource allocation across large-scale cloud computing environments. In the coming years, this demand will further increase, so understanding the operation of network switches is crucial.