Patent ID: 6839352

Claim:
A single-chip Synchronous Optical Network SONET) physical layer device comprising: a single integrated circuit comprising first, second and third interface ports; an Asynchronous Transfer Mode (ATM) interface circuit fabricated on the single integrated circuit and coupled to the first interface port for receiving a plurality of ATM cells, which together carry a first data unit, from the first interface port; a Point-to-Point Protocol (PPP) processing circuit fabricated on the single integrated circuit and coupled to the second interface port and the ATM interface circuit for receiving a second data unit from the second interface port or the first data unit from the ATM interface circuit, wherein the PPP processing circuit is adapted to place one of the first data unit and the second data unit into a PPP frame; a SONET framer circuit fabricated on the single integrated circuit and coupled between the ATM interface circuit and the third interface port and between the PPP processing circuit and the third interface port, wherein the SONET framer circuit is adapted to receive the ATM cells from the ATM interface circuit or the PPP frame from the PPP processing circuit and place the ATM cells or the PPP frame into a SONET frame; a first transmission path from the first interface port to the ATM interface circuit, through the ATM interface circuit to the SONET framer circuit, and through the SONET framer circuit to the third interface port; a second transmission path from the first interface port to the atm interface circuit, through the ATM interface circuit to the PPP processing circuit, through the PPP processing circuit to the SONET framer circuit, and through the SONET framer circuit to the third interface port; and a third transmission path from the second interface port to the PPP processing circuit, through the PPP processing circuit to the SONET framer circuit, and through the SONET framer circuit to the third interface port.