US 2003O223446A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2003/0223446A1 Lewin et al. (43) Pub. Date: Dec. 4, 2003 (54) SYSTEM FOR ENCAPSULATING (52) U.S. Cl. ............................................ 370/419,375/220 ETHERNET FRAMES OVERVERY HIGH SPEED DIGITAL SUBSCRIBER LINES (57) ABSTRACT (75) Inventors: Amit Lewin, Tel Aviv (IL); Opher An apparatus for and method of encapsulating Ethernet Yaron, Tel Aviv (IL); Alon Hurwitz, frame data in Very high speed Digital Subscriber Line Ramat Gan (IL); Yuri Poddobny, (VDSL) frames. The VDSL frames are transmitted over a Herzelia (IL) point to point VDSL link where they are subsequently extracted and forwarded as standard Ethernet frames. The Correspondence Address: VDSL facility transport system comprises an Ethernet to Edward K. Runyan VDSL Consumer Premises Equipment (CPE) coupled to a McDonnell Boehnen Hulbert & Berghoff DSL Access Multiplexor (DSLAM) over a VDSL transport 32nd Floor facility. The Ethernet to VDSL CPE functions to receive a 300 S. Wacker Drive 10BaseTEthernet signal and encapsulate the Ethernet frame Chicago, IL 60606 (US) into a VDSL frame for transmission over the VDSL facility. The DSLAM is adapted to receive VDSL frames, extract (73) Assignee: 3COM CORPORATION Ethernet frames therefrom and generate and output a stan dard Ethernet Signal. Ethernet frames are encapsulated (21) Appl. No.: 10/430,480 within VDSL frames and transmitted on the wire pair without regard to the state of the SOC signals. This over (22) Filed: May 6, 2003 comes the problems associated with Syncing the transmis Related U.S. Application Data sion of the Ethernet data with the SOC signals. The present invention also provides a method of providing the receiving (63) Continuation of application No. 09/318,887, filed on station an indication of the start of a VDSL frame. A May 26, 1999, now Pat. No. 6,608,834. preamble having certain desirable characteristics Such as good autocorrelation properties, is used by the receiving Publication Classification station to identify the start of a VDSL frame. To further ensure that a detected Start of frame is valid, the length field (51) Int. Cl. .................................................. H04L 12/56 of the VDSL frame is examined for a legal length value. 42 ETHERNET FAST ETHERNET ETHERNET OOBoseT ENCAPSULATION/ EXTRACTION SWITCH TRANSCEIVER ETHERNET Patent Application Publication Dec. 4, 2003 Sheet 2 of 5 US 2003/0223446 A1 F ?IT?R?T------------------?B?s?? Z|/ Patent Application Publication Dec. 4, 2003. Sheet 3 of 5 US 2003/0223446A1 7/ -9#7SELVEZS3LÅGOOG| SELR88|9-79H10NETEW\/\{}|ENYJEHLE 0/2.89ZZ SBLÅG9 BWAHHNHHHH 08 SBLAG/ ETEWWE)'d Patent Application Publication Dec. 4, 2003. Sheet 4 of 5 US 2003/0223446A1 |70|| 96 EN?HEINT?Z?T????E?T?N?INTELEWERRITOõõõõõõõõõõ|VIVO1000E, SELKEZ S?D?T??TFTZTEIÐN?T?W?JITSJAI 9'0||H.Lae-08 HABTX)| -OOS Patent Application Publication Dec. 4, 2003 Sheet 5 of 5 US 2003/0223446A1 71 RECEIVER SYNCHRONIZATION UNT FOR PREAMBLE PREAMBLE YO N PATTERN DETECTED 2 YES 120 READ IN LENGTH FIELD - ASSERT Rx ERR LENGTH < 64 OR > 1518 ?)YES - NO READ IN REMAINDER OF 118 VDSL FRAME FIG.8 US 2003/0223446 A1 Dec. 4, 2003 SYSTEM FOR ENCAPSULATING ETHERNET 0005. As use of the Internet and online services continues FRAMES OVER WERY HIGH SPEED DIGITAL to spread, So does the use of more complex applications, SUBSCRIBER LINES Such as interactive Video games, telecommuting, business to business communications and Videoconferenceing. These FIELD OF THE INVENTION complex applications place Severe Strains on data networks 0001. The present invention relates generally to data because of the intensive bandwidth required to deliver communication Systems and more particularly relates to a data-rich transmissions. For example, a telecommuter who System for transporting Ethernet frames over Very high requires computer aided design (CAD) Software to be trans ported over the data network requires a high-bandwidth data speed Digital Subscriber Lines (VDSL). pipeline because of the Significant size of CAD files. Simi BACKGROUND OF THE INVENTION larly, a business to business transaction in which large database files containing thousand of customer records are 0002 There is a growing need among both individuals eXchanged also consumes large amounts of bandwidth. The and enterprises for access to a commonly available, cost Same is true for users Seeking entertainment value from Sites effective network that provides Speedy, reliable Services. offering high quality Video and audio. The lack of available There is high demand for a high-Speed data network, one bandwidth in today's data networks is the primary barrier with enough bandwidth to enable complex two-way com preventing many applications from entering mainstream use. munications. Such an application is possible today if, for Just as processing power limited the effectiveness of early example, access is available to a university or a corporation PCs, bandwidth constraints currently limit the capabilities of with sufficient finances to build this type of network. But for the average home computer user or Small business, access to today's modem user. high Speed data networks is expensive or Simply impossible. 0006 Most computer modem users access data through Telephone companies are therefore eager to deliver broad the Standard telephone network, known as plain old tele band Services to meet this current explosion in demand. phone service (POTS). Equipped with today's speediest modems, dial up modems on a POTS network can access 0003. One of the problems is that millions of personal data at a rate of 28.8, 33.6 or 56 Kbps. Dial up modem computers have found their place in the home market. transmission rates have increased significantly over the last Today, PCs can be found in approximately 43% of all United few years, but POTS throughput is ultimately limited to 64 States households and a full 50% of United States teenagers Kbps. While this rate may be acceptable for some limited own computers. Virtually every PC sold today is equipped applications like e-mail, it is a Serious bottleneck for more with a modem, enabling communication with the outside complex transactions, Such as telecommuting, Videoconfer world via commercial data networks and the Internet. Cur enceing or full-motion video viewing. To illustrate, full rently, people use their PCS to Send and receive e-mail, to motion Video compressed, using the Motion Picture Enter access online Services, to participate in electronic commerce tainment Group (MPEG)-2 standard requires a data stream and to browse the Internet. The popularity of the Internet is of approximately 6 Mbps, or roughly 208 times the through Such that there are an estimated 50 million users around the put of a 28.8 Kbps modem. Thus, using today's dial up globe. These figures indicate that in the past few years the modems, it would take more than 17 days to capture two personal computer has fueled a dramatic increase in data hours of Video. AS bandwidth demands continue to grow, communications and the corresponding demands on the data providerS Search for better ways to offer high Speed data networks that carry the traffic. access. Further complicating the problem is the need to 0004. The Internet serves as a good example of the deliver all these complex Services at an affordable price. increased demands that have been placed on data networkS. 0007 Today's most popular data access method is POTS. At first, Internet acceSS consisted of text only data transferS. But as discussed previously, POTS is limited when it comes Recently, with the popularity of the World Wide Web to large data transfers. An alternative to POTS currently (WWW) and the construction of numerous sites with high available is Integrated Services Digital Network (ISDN). In quality content, coupled with the development of Internet the past few years, ISDN has gained momentum as a browsers such as Mosaic, Netscape Navigator and Microsoft high-speed option to POTS. ISDN expands data throughput Explorer, the use of graphics, audio, Video and text has to 64 or 128 Kbps, both from the network to the home and Surged on the Internet. While graphics, audio and Video from the home back to the network, and can be technically make for a much more interesting way to View information made available throughout much of the United States and in as opposed to plain text, bandwidth consumption is signifi many other parts of the globe. Similar to POTS, ISDN is a cantly more. A simple background picture with accompa dedicated Service, meaning that the user has Sole access to nying text requires approximately 10 times the bandwidth the line preventing other ISDN users from sharing the same needed by text alone. Real-time audio and Streaming video bandwidth. ISDN is considered an affordable alternative, typically need even more bandwidth. Because of the and in general, ISDN is a much better Solution for applica increased requirement for bandwidth, activities Such as tions Such as Web browsing and basic telecommuting. browsing home pages or downloading graphics, audio and However, like POTS, it severely limits applications such as Video files can take a frustratingly long period of time. telecommuting with CAD files and full-motion video view Considering that the multimedia rich World Wide Web ing. The latter requires roughly 39 times the throughput than accounts for more than one quarter of all Internet traffic, it that provided by ISDN. Multichannel multipoint distribution is easy to See why the demand for bandwidth has outpaced service (MMDS), a terrestrial microwave wireless delivery the Supply. In addition, the creative community is pushing System, and direct broadcast Satellite (DBS), Such as the envelope by offering audio and full motion video on DirecTV and US Satellite Broadcasting (USSB), are wireless numerous sites to differentiate themselves from the millions networks.