Memory controller in a multi-port bridge for a local area network

Abstract

A memory controller in a multi-port bridge for a local area network. The multi-port bridge includes a switch engine, a memory and a plurality of ports, all of which are interconnected by a high speed communication bus. The memory includes look-up tables utilized for appropriately directing data packets among the ports, packet buffers utilized for temporarily storing packets and mailboxes for providing an interface between the switch engine and an external processor. The switch engine includes the memory controller, a bus controller and a look-up controller, each preferably including a finite state machine. The memory controller provides an interface between the memory and the communication bus by including a command decoder for decoding bus commands received from the communication bus. For example, the command decoder provides a response to memory read and write bus commands. In addition, the memory controller includes a memory control finite state machine for controlling operation of the memory controller according to the bus commands received from the command decoder. The memory controller also includes logic and address registers for providing appropriate row and column addresses to the memory device according to a current state of the memory control finite state machine. Because the memory control finite state machine controls operation of the memory controller, memory read and write operations are performed with a minimum of delay, thereby increasing the throughput capacity of the multi-port bridge.