3Com Corporation

Brian W Bailey

John A Flanders

William D Townsend

Thomas V Radogna

Ryan T Ross

Thomas A Lemaire

Robert A Ciampa

Marc D Sousa

Thomas A Lamaire

A network bridge/router for identifying a data unit to be routed by a network bridge/router, for identifying a protocol associated with the received data unit to be routed, and for carrying out appropriate data unit transfer operations, all in hardware. A Receive Header Processor (RHP) analyzes the destination address of the received data unit, in hardware, for determining if routing or bridging is required. If routing is required, the RHP uses portions of the received data unit header as a compare value against predefined values stored in data structures which provide a protocol ID identifying the protocol of the received data unit and serving as an index to the appropriate microcode handling routine, executed by the RHP, for the data unit. The handling routine causes the RHP to forward data unit identifying information appropriate to the identified protocol and obtained from the received data unit to further hardware-based data unit processing elements. These further data unit processing elements are adaptable to the received data unit cast state (e.g. unicast, multicast, broadcast), bridging and/or routing requirements, and received data unit protocol.

Multiple protocol support

At least a portion of the data units in a bridge/router are processed by logic circuits according to cast type. The cast type, source address and destination address of an incoming data unit are determined by examining the header. For a unicast data unit, the source address and destination address are employed to obtain a transmit port indicator from memory, and the unicast data unit is directed to the port indicated by the transmit port indicator. For a non-unicast data unit, the source address and destination address are employed to obtain a first port mask that indicates valid ports for receipt of the data unit and a second port mask that indicates valid ports for transmission of the data unit from memory. The first and second port masks are combined to generate a third port mask, and the non-unicast data unit is directed to the ports indicated by the third port mask.

Unicast, multicast, and broadcast method and apparatus

Growing community of inventors

Lunenburg, MA, United States of America

Brian W Bailey