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Abstract

A bridging device for mapping and demapping Ethernet data packets onto a SONET network includes an Ethernet controller chip set which receives packet data, a SONET framer for a SONET interface, a UTOPIA interface for the SONET framer, and an FPGA (or ASIC) which bridges the UTOPIA interface and a system bus interface of the Ethernet controller. The FPGA is preferably implemented in VHDL software code as several modules: an Ethernet controller interface module, a chunk memory module, a UTOPIA interface module, a microprocessor interface module, and a UTOPIA OUT module. In a transmit mode, the Ethernet controller interface module interfaces with the data and control signals from a thirty-two bit data bus of the Ethernet controller chip set and writes the data to chunk memory implemented in the FPGA. The chunk memory module implements the chunk memory to a programmable size. The UTOPIA interface module implements an interface with data and control bus signals of Fr-UTOPIA and reads data sixteen bits at a time from chunk memory and writes the data to the Fr-UTOPIA interface bus. The microprocessor interface module implements the control and status registers. The UTOPIA OUT module implements address and data bus drivers and control signals of the Fr-UTOPIA data bus. A top level module instantiates the modules with proper signals. The bridging device is also adapted for a receive mode in which an FPGA operates substantially in reverse.

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