When the switch processes the received data frame, it identifies which VLAN (Virtual Local Area Network) it belongs to based on the information in the data frame. The following are the steps for the switch to identify the VLAN to which the data frame belongs:
1.Read the information in the data frame: When the switch receives a data frame, it first reads the information in the data frame, including the source MAC address, destination MAC address, and VLAN identifier (VLAN ID).
2.Check the MAC address table: The MAC address table inside the switch records the port and VLAN to which each MAC address belongs. By looking up the MAC address table, the switch can determine the VLAN to which the data frame belongs.
3.Check the VLAN configuration: The vlan configuration information is also saved, including the VLAN name, IP address, and subnet mask. The switch compares the VLAN identifier in the data frame with the configuration information to determine the VLAN to which the data frame belongs.
4.Filter data frames that do not belong to a VLAN: If the VLAN identifier in the data frame does not match the configuration information of the switch, or if the data frame does not have a VLAN identifier, the switch discards the data frame by default.
5.Data Frame of the Belonging VLAN: If the data frame belongs to one of the VLANs of the switch, the switch sends it to the corresponding port. During the process, the switch also modifies the VLAN identifier of the data frame as needed.
Through the above steps, the switch is able to accurately identify the VLAN to which the received data frame belongs and correctly send it to the destination port. This helps to improve the flexibility and security of the network, allowing communication between different VLANs to be isolated and managed.