Ethernet frame encapsulation over VDSL using HDLC

Abstract

An apparatus for and method of encapsulating Ethernet frame data in HDLC frames for transmission over a VDSL transport facility. The HDLC frames are transmitted over a point to point VDSL link where they are subsequently extracted and forwarded as standard Ethernet frames. The VDSL facility transport system comprises one or more Ethernet to VDSL CPEs coupled to a DSLAM over a VDSL transport facility. The Ethernet to VDSL CPE functions to receive a 10BaseT Ethernet signal and encapsulate the Ethernet frame into a HDLC frame for transmission over the VDSL facility. In one embodiment, a single chip microcontroller on the CPE performs both Ethernet controller and HDLC controller functions. The DSLAM is adapted to receive HDLC frames from one or more CPEs, extract Ethernet frames therefrom and generate and output a standard Ethernet signal. Ethernet frames are encapsulated within HDLC frames and transmitted on the wire pair without regard to the state of the SOC signals. This overcomes the problems associated with synchronizing the transmission of the Ethernet data with the SOC signals.

What is claimed is:  
     
         1 . A method of transporting Ethernet frames over a Very high speed Digital Subscriber Line (VDSL) transport facility coupling a first communication device and a second communication device, said method comprising the steps of: 
 receiving an input Ethernet frame data on said first communication device from a first Ethernet compatible communication device coupled thereto;    encapsulating said received Ethernet frame within a High level Data Link Control (HDLC) frame;    transmitting said HDLC frame over said VDSL transport facility;    receiving HDLC frame data on said second communication device;    extracting said Ethernet frame from said received HDLC frame and generating an output Ethernet frame therefrom; and    transmitting said output Ethernet frame to a second Ethernet compatible communication device coupled to said second communication device.    
     
     
         2 . The method according to  claim 1 , wherein said step of encapsulating comprises the step of stripping off the preamble, start of frame fields and Cyclic Redundancy Check (CRC) fields from said Ethernet frame and calculating a new CRC before placing said Ethernet frame in said HDLC frame.  
     
     
         3 . The method according to  claim 1 , wherein said step of generating comprises the step of adding Ethernet preamble and Ethernet start of frame fields and calculating a new CRC and appending it to said extracted Ethernet frame.  
     
     
         4 . An Ethernet transport system for transporting Ethernet frames over one or more Very high speed Digital Subscriber Line (VDSL) transport facilities, said system comprising: 
 a plurality of channels wherein each channel comprises an Ethernet to VDSL Customer Premise Equipment (CPE) adapted to encapsulate Ethernet frames from a first Ethernet source into HDLC frames for transmission over said VDSL transport facility and to extract Ethernet frames from HDLC frames received over said VDSL transport facility;    an access multiplexor adapted to interface with said plurality of channels, said access multiplexor adapted to encapsulate Ethernet frames from a second Ethernet source into HDLC frames for transmission to one of said plurality of channels and to extract Ethernet frames from HDLC frames received over said plurality of channels.    
     
     
         5 . The system according to  claim 4 , wherein each channel comprises a microcontroller adapted to function as both an Ethernet controller and an HDLC controller.  
     
     
         6 . An Ethernet transport system for transporting Ethernet frames over one or more Very high speed Digital Subscriber Line (VDSL) transport facilities, said system comprising: 
 a plurality of channels wherein each channel comprises an Ethernet to VDSL Customer Premise Equipment (CPE), each CPE comprising: 
 means for receiving an Ethernet frame from a first Ethernet source and encapsulating it within a High level Data Link Control (HDLC) frame;  
 means for transmitting said HDLC frame onto one of said VDSL transport facilities;  
 means for receiving said HDLC frame from one of said VDSL transport facilities; and  
 means for extracting said Ethernet frame from said HDLC frame and forwarding it to said first Ethernet source;  
   an access multiplexor adapted to interface with said plurality of channels, said access multiplexor comprising: 
 an Ethernet switch having a plurality of ports;  
 means for receiving from each channel, HDLC frames from a corresponding VDSL transport facility;  
 means for extracting Ethernet frames from said HDLC frames and inputting then to a port on said switch  
 means for transmitting Ethernet frames from said Ethernet to a second Ethernet source;  
 means for receiving Ethernet frames from said second Ethernet source and inputting them to said switch;  
 means for encapsulating said Ethernet frames output of said switch into HDLC frames; and  
 means for transmitting said HDLC frames onto one of said VDSL transport facilities.  
   
     
     
         7 . The system according to  claim 6 , wherein said means for encapsulating and extracting on each of said channels comprises a microcontroller adapted to function as an Ethernet controller and an HDLC controller.