Stacking allows several physical switches to be combined as a logical unit (common MAC and IP address) for convenient maintenance and management. Access switches of any size can be connected to any free downlink port of this aggregation switch stack. The result: The LAN-side foundation for very large network infrastructures. For maximum fail safety, each access switch is simultaneously connected to two aggregation switches. If one of the two aggregation switches fails, the connection between the access and aggregation levels continues undiminished.