METHOD AND APPARATUS FOR PROVIDING A GIGABIT ETHERNET CIRCUIT PACK
Method and system for providing data transmission with transparency over the Gigabit Ethernet data stream includes receiving the 10 bit code with a data rate of 1,250 Mbits/second from the encoded 8B/10B data and arbitrarily selecting 9 bit codes using a look-up translation table which can fully represent the 10 bit codes received. The translated 9 bit codes with a data rate of 1,125 Mbits/second is then provided to eight STS-3 inverse multiplexer which inverse multiplexes the received codes into eight STS-3 data streams each with a data rate of 155.52 Mbits/second plus an offset Δ which are then provided to the modem for transmission to the far end via the optical transmission path.
This application claims priority under 35 USC § 119 to provisional application No. 60/269,225 entitled “Method and Apparatus for Providing a Gigabit Ethernet Circuit Pack” filed on Feb. 14, 2001, and to provisional patent application entitled “System and Method for Recovering RZ Formatted Data Using NRZ Clock and Data Recovery,” having inventors Nicholas J. Possley and David B. Upham, filed May 9, 2001, the disclosures of each of is incorporated herein by reference for all purposes.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates to data network systems. In particular, the present invention relates to method and apparatus for providing transparently transporting 155 Mb/s signals through a high speed data network.
2. Description of the Related Art
Optical fiber is a transmission medium that is well suited to meet the increasing demand in data transmission in communication networks. Generally, optical fiber has a much greater bandwidth than metal-based transmission medium such as twisted copper pair or coaxial cable, and protocols such as the OC protocol have been developed for the transmission of data over optical fibers. Typical communications system based on optical fibers include a transmitter, an optical fiber, and a receiver. The transmitter converts the data to be transported into an optical form using the proper protocol and then transmits the resulting optical signal over the optical fiber to the receiver, where the original data is recovered from the optical signal.
While adding more optical fiber to the existing communications network infrastructure is a costly option to meet the increasing demand for communication bandwidth, in some locations, expanding the existing network may not be a viable alternative. Additionally, given the high cost of installation and the extensive amount of time required, adding more optical fiber is not always an attractive option to increase communications bandwidth.
Due to the large bandwidth capability of optical fibers, this type of transmission medium is most efficiently utilized when multiple users share the medium. In general, a number of low-speed data streams (“low speed channels”) transmitted by different users may be combined into a single high-speed channel for transporting across the optical fiber medium. At the opposite end of the communications network, when the high-speed channel reaches the destination for one of the low-speed channels that it is transporting, the low-speed channel must be extracted from the high-speed channel.
A typical optical communications network includes nodes (for example, central offices) which transmit high-speed channels to each other over optical fibers. In addition to transporting low-speed channels through the nodes (commonly referred to as the “pass-through” function) as part of high-speed channels passing through the nodes, nodes may also combine incoming low-speed channels to the high-speed channel (i.e., the “add” function) and/or extract outgoing low-speed channels from the high-speed channels (the “drop” function). These functions are commonly referred to as add-drop multiplexing (ADM).
For example, wavelength division multiplexing (WDM) and time division multiplexing (TDM) are two known approaches to combining low-speed channels into a high-speed channel. In WDM and its counterpart dense wavelength division multiplexing (DWDM), each low-speed channel is placed on an optical carrier of a different wavelength and the different wavelength carriers are combined to form the high-speed channel. Crosstalk between the low-speed channels is a significant concern in WDM, and thus the wavelengths for the optical carriers must be spaced sufficiently far apart (typically 50 GHz or more) so that the different low-speed channels are resolvable.
In TDM, each low-speed channel is compressed into a certain time slot and the time slots are then combined on a time basis to form the high-speed channel. For example, given a certain period of time, the high-speed channel may be capable of transporting 10 bits while each low-speed channel may only be capable of transmitting 1 bit. In this case, the first bit of the high-speed channel may be allocated to low-speed channel 1, the second bit to low-speed channel 2, and so on, thus forming a high-speed channel containing 10 low-speed channels. Generally, TDM requires precise synchronization of the different channels on a bit-by-bit basis (or byte-by-byte basis, in the case of SONET), and a memory buffer is typically also required to temporarily store data from the low-speed channels.
SUMMARY OF THE INVENTIONIn view of the foregoing, a method of transporting data through a data network, in accordance with one embodiment of the present invention includes the steps of receiving an encoded data, mapping the received data to a predetermined data; and multiplexing the mapped predetermined data.
In particular, the encoded data may be an 8B/10B encoded data which includes either a Gigabit Ethernet data and a Fiber Channel data.
The receiving step may further include the step of determining a data rate of the received encoded data, and the step of recovering a clock signal from the received encoded data.
The clock signal may have a rate one tenth of said data rate, where the predetermined data may include a 9-bit data. In turn, the 9-bit data may include one of an arbitrary set of 9-bit data.
The multiplexing step may include the step of synchronizing the multiplexed predetermined data, where the multiplexed predetermined data may be synchronized to a predetermined clock signal, and further, where the predetermined clock signal may include a phase locked loop clock signal.
An apparatus for providing data transport through a data network in accordance with another embodiment of the present invention includes a clock recovery unit configured to receive an encoded data, a data translation unit coupled to the clock recovery unit, configured to translate the received data to a predetermined data, and an inverse multiplexer coupled to the data translation unit, configured to inverse multiplex the translated predetermined data.
The encoded data may include 8B/10B encoded data, and in particular, one of a Gigabit Ethernet data and a Fiber Channel data.
The clock recovery unit may additionally detect a data rate of the received encoded data, and further, the clock recovery unit may be further configured to recover a clock signal from the received encoded data.
The clock signal may have a rate one tenth of said data rate.
Additionally, the predetermined data may include a 9-bit data, where the 9-bit data may include one of an arbitrary set of 9-bit data.
The inverse multiplexer may be further configured to synchronize the multiplexed predetermined data to a predetermined clock signal, where the predetermined clock signal may include a phase locked loop clock signal.
Additionally, a modem may be coupled to the inverse multiplexer to receive the inverse multiplexed translated predetermined data for transmission.
The inverse multiplexed translated predetermined data may include a plurality of STS-3 signals, where the plurality of STS-3 signals may include eight STS-3 signals for transmission.
An apparatus for providing data transport in a network in accordance with yet another embodiment of the present invention includes a demultiplexer configured to demultiplex received data, a data translation unit coupled to the multiplexer configured to translate the demultiplexed data to a predetermined data, and a serializer coupled to the data translation unit configured to receive the translated predetermined data and accordingly to generate a corresponding encoded data.
The received data may include a plurality of STS-3 signals, where the plurality of STS-3 signals may include eight STS-3 signals. Additionally, a plurality of FIFOs may be provided, each configured to frame align the STS-3 signals, the frame aligned STS-3 signals corresponding to the received signal.
The demultiplexed data may include a 9-bit data, where the 9-bit data may have a data rate of 1,125 Mbits/second.
The demultiplexer may be further configured to perform parity checks on the received data.
The predetermined data may include a 10-bit data.
The serializer may be configured to synchronize the translated predetermined data, where the translated predetermined data may include a 10-bit data, and further, where the 10-bit data may have a data rate of 1,250 Mbits/second.
The encoded data may include an 8B/10B encoded data.
A method for providing data transport in a network in accordance with still another embodiment of the present invention includes the steps of demultiplexing a received data, translating the demultiplexed data to a predetermined data, generating a corresponding encoded data based on the translated predetermined data.
The received data may include a plurality of STS-3 signals, where the plurality of STS-3 signals may include eight STS-3 signals. The method may further include the step of frame aligning each of the STS-3 signals, the frame aligned STS-3 signals corresponding to the received data for demultiplexing.
The demultiplexed data may include a 9-bit data, where the 9-bit data may have a data rate of 1,125 Mbits/second.
Additionally, the method above may further include the step of performing parity checks on the received data, as well as the step of synchronizing the translated predetermined data.
The translated predetermined data may include a 10-bit data, where the 10-bit data may have a data rate of 1,250 Mbits/second.
Finally, the encoded data may include an 8B/10B encoded data.
In the manner described, the present invention discloses method and system for providing data transmission with transparency over the Gigabit Ethernet as well as other data stream which includes receiving the 10 bit code with a data rate of 1,250 Mbits/second from the encoded 8B/10B data and arbitrarily selecting 9 bit codes using a look-up translation table which can fully represent the 10 bit codes received. The translated 9 bit codes with a data rate of 1,125 Mbits/second is then provided to eight STS-3 inverse multiplexer which inverse multiplexes the received codes into eight STS-3 data streams each with a data ate of 155.52 Mbits/second which are then provided to the modulator at the near end and demodulator at the far end.
These and other features and advantages of the present invention will be understood upon consideration of the following detailed description of the invention and the accompanying drawings.
Referring back to
As further shown, the data translation unit 120 is configured to translate the received 10-bit data to a corresponding 9-bit data. In particular, the system 100 queries the translation table 121 to determine the 9-bit data corresponding to the received 10-bit data. In one aspect of the present invention, the 10-bit to 9-bit translation table 121 of the data translation unit 120 may include 464 unique 9-bit codes, each corresponding to a separate one of the received 10-bit data. Moreover, the 9-bit codes may be arbitrarily chosen. Additionally, as shown in the Figure, 10 bit data received from clock recovery unit 110 which do not require translation is passed through the data translation unit 120 which uses the translation table 121 to determine whether the received data bit code is valid, and outputs the valid confirmed 10 bit data to the 8xSTS-3 inverse multiplexer 130.
Furthermore, as will be discussed below, any 10-bit data received which does not map to one of the 464 9-bit codes in the translation table 121 may result in a /V/ code translation indicating an error. It should be noted that /V/ codes are 10-bit codes defined by IEEE to be used for error propagation. In particular, /V/ codes are inserted as data in the STS-3 frame when a LOSYN defect or LOS defect exists on the add direction input. In particular, in the case of Gigabit Ethernet or Fiber Channel data streams, for a LOSYN defect, as soon as a comma is detected, the /V/ code insertion ceases.
The translated 9-bit data with a data rate of 1,125 Mbits/second is provided to the inverse multiplexer 130 which, along with the phase lock looped clock signal from the PLL unit 150, inverse multiplexes the received 9-bit data into corresponding STS-3 signals. In one aspect, the phase lock looped clock signal from the PLL unit 150 is at 155.52 MHz with an offset Δ, where the offset Δ is a 20 ppm (parts per million) or less offset. Indeed, with the incoming bit data determined, the PLL unit 150 locks onto the incoming data rate. An ADD PLL alarm may be configured to indicate the status of the PLL unit 150—whether the PLL unit 150 is in locked or unlocked state. This permits the overall system to maintain the timing on the clock instead of the data. Furthermore, in another embodiment, variable bit stuffing may be implemented as will be discussed in further detail below. With both cases, since the add direction clock signal is locked onto the incoming data, the data will fit exactly into the data frames shown in
Moreover, in addition to inverse multiplexing the 9-bit data into eight STS-3 signals, the inverse multiplexer 130 is further configured to provide variable byte stuffing. Then, the eight STS-3 signals, each at a data rate of 155.52 Mbits/second+offset Δ with all eight STS-3 signals synchronized and frame aligned, are provided to a modem 140 for transmission via the optical transmission line to the drop side. In particular, the modem 140 includes eight modulators one for each STS-3 signal output from the STS-3 inverse multiplexer 130. More specifically, each of the eight modulators together comprising the modem 140 is similar to modulator as described in pending U.S. patent application Ser. No. 09/571,349, filed May 16, 2000 by inventors David A. Pechner and Laurence J. Newell entitled “Through-Timing of Data Transmitted Across an Optical Communications System Utilizing Frequency Division Multiplexing” assigned to the assignor of the present application, and the disclosure of which is incorporated herein by reference for all purposes.
As discussed above, in accordance with one embodiment of the present invention, 8B/10B encoded data which includes, for example, Gigabit Ethernet and Fiber Channel signals, may be fully represented by 9 bits and may be transported transparently to ensure that parity and special code functions are passed on to the customers. Furthermore, in one aspect of the present invention, the PLL unit 150 and the clock recovery unit 110 may be configured to permit the overall system 100 to “tune” to each of the signal rates, such as, for example, in the case of Gigabit Ethernet data whose rate is approximately 1,250 Mb/s encoded and approximately 1,000 Mb/s decoded.
Referring to
In particular, in accordance with one aspect of the present invention, the STS-3 multiplxer/9-bit demultiplexer 220 may be configured to perform parity checks and to demultiplex the 9 bits from the received eight STS-3 signals. The recovered 9-bit data with a data rate of 1,125 Mbits/second is then provided to the data translation unit 230 which includes a 9-bit-to-10-bit translation table 231. In one embodiment, the system 200 may be configured to retrieve a corresponding 10-bit data for the recovered, received 9-bit data from the STS-3 multiplexer/9-bit demultiplexer. As will be discussed in further detail below, in one embodiment, the 9-bit to 10-bit translation table 231 of the data translation unit 230 may be a look-up table stored in the data translation unit 230 under the control of a controller (not shown) of the data translation unit 230. In particular, the translation table 231 may be, in one embodiment, stored in a storage unit within the data translation unit 230, where the storage unit may include a memory such as a random access memory.
Referring back to
As further shown in
The frame aligned 9-bit data from the respective FIFO leak buffer 430 is the provided to the respective elastic store units 440. More particularly, the FIFO leak buffer 430 is configured to send the 155.52 clock signal in addition to the 9-bit data. The elastic store unit 440 is also configured to receive the 9-bit data from the FIFO leak buffer 430. The 155.52 MHz clock signal from the FIFO leak buffer 430 is also provided to the respective elastic store units 440 as well as to a logical OR 490.
Referring back to
Referring back to
In one embodiment, the VRVH circuit pack is configured to support non-standard signals in the range from 565 Mb/s to 1,184.265 Mb/s. In particular, the STS-3 frame shown in
Referring to
Referring to
As discussed above, in accordance with one embodiment of the present invention, in the add direction, the Gigabit Ethernet, RZ signals, or Fiber Channel data is inverse multiplexed into eight pseudo STS-3 data streams. The data network system 100 then modulates and sums the data stream with all other data streams for transport over an optical fiber connection. At the far end, the data network system 100 receives the eight pseudo STS-3 signals from the modem 140 and multiplexes the data back into the original high speed data stream. Pending U.S. patent application entitled “Variable Rate High-Speed Input and Output in Optical Communication Network,” having inventors Tian Shen, Robert B. Clarke, Jr., Thomas J. Roman, David B. Upham, David A. Pechner, and Laurence J. Newell, filed on May 8, 2001, and assigned to the assignee of the present application, Kestrel Solutions, Inc., provides additional examples of variable rate high speed input and output in an optical network using optical frequency division multiplexing, the disclosure of which is incorporated in its entirety by reference for all purposes.
In the drop direction, the data network system 100 may be configured to receive both sets of eight data streams from each of the drop cross-connects. Accordingly, SONET framers may be used to frame-up each of the pseudo STS-3s, with the delay compensated for between each of the pseudo STS-3's in each set of eight data streams. It should be noted that the delay is compensated for between the pseudo STS-3's in a set. In one aspect, the maximum delay between any pseudo STS-3 is approximately 26.3 μs. Since this delay value is much less than the frame period of approximately 125 μs, the alignment of the pseudo STS-3's may occur where the framing pulses are nearest to each other. Moreover, it should be noted that in both the add and drop directions, the system 100 may be configured to perform a predetermined level of performance monitoring and fault detection on the data stream.
In one aspect of the present invention, a Gigabit Ethernet Circuit Pack proposed by the assignee of the present invention, Kestrel Solutions, is configured to provide an additional interface added to the low speed shelf, the added interfaces including 1250 Mbps Gigabit Ethernet, 1062.5 Mbps Fiber Channel, 1129.984 Mb/s Return-to-Zero (RZ) data and 564.992 Mbps RZ data. The circuit pack is thus configured to provide the functionality of transparently transporting these signal formats through the backend of a data network which is through-timed from the input signals.
In particular, as discussed above, since both the Gigabit Ethernet and the Fiber Channel signals are encoded using the 8B/10B encoding scheme, the 8 bits are transmitted into 10 bits for the purpose of transition density of data for the clock recoveries and parity information for additional error detection. Indeed, since the 8 bits are mapped into two sets of 10-bit codes, the two sets providing the parity information, it can be seen that only a maximum of 512 different codes need be used. Furthermore, by examining the code table in IEEE 802.3 publication, it can be seen that 72 of the 512 codes are duplicates, which leaves 440 codes for the data. Additionally, apart from the data, IEEE 802.3 publication defines 12 special codes used for various functions such as start-of-packet, error propagation, end-of-pocket, idle, and so on, with parity that gives 24 codes. Therefore, the total number of codes is 464 codes, which can be fully represented by 9-bit codes. Indeed, in accordance with one aspect of the present invention, to ensure that parity and special code functions are passed onto the customers, the data may be transported transparently, as described above, for example, where 9-bit codes can fully represent the data.
In the manner described above, in accordance with the present invention, there is provided method and system for providing data transmission with transparency over the Gigabit Ethernet data stream which includes receiving the 10 bit code with a data rate of 1,250 Mbits/second from the encoded 8B/10B data and arbitrarily selecting 9 bit codes using a look-up translation table which can fully represent the 10 bit codes received. The translated 9 bit codes with a data rate of 1,125 Mbits/second is then provided to eight STS-3 inverse multiplexer which inverse multiplexes the received codes into eight STS-3 data streams each with a data rate of 155.52 Mbits/second+offset Δ which are then provided to the modem at the far end.
Various other modifications and alterations in the structure and method of operation of this invention will be apparent to those skilled in the art without departing from the scope and spirit of the invention. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. It is intended that the following claims define the scope of the present invention and that structures and methods within the scope of these claims and their equivalents be covered thereby.
Claims
1. A method of transporting data through a data network, comprising the steps of:
- receiving an encoded data;
- mapping said received data to a predetermined data; and
- multiplexing said mapped predetermined data.
2. The method of claim 1 wherein said encoded data includes 8B/10B encoded data.
3. The method of claim 2 wherein said encoded data includes one of a Gigabit Ethernet data and a Fiber Channel data.
4. The method of claim 1 wherein said step of receiving further includes the step of determining a data rate of said received encoded data.
5. The method of claim 4 wherein said step of receiving further includes the step of recovering a clock signal from said received encoded data.
6. The method of claim 5 wherein said clock signal has a rate one tenth of said data rate.
7. The method of claim 1 wherein predetermined data includes a 9-bit data.
8. The method of claim 7 wherein said 9-bit data includes one of an arbitrary set of 9-bit data.
9. The method of claim 1 wherein said multiplexing step includes the step of synchronizing said multiplexed predetermined data.
10. The method of claim 9 wherein said multiplexed predetermined data is synchronized to a predetermined clock signal.
11. The method of claim 10 wherein said predetermined clock signal includes a phase locked loop clock signal.
12. An apparatus for providing data transport through a data network, comprising:
- a clock recovery unit configured to receive an encoded data;
- a data translation unit coupled to said clock recovery unit, configured to translate said received data to a predetermined data; and
- an inverse multiplexer coupled to said data translation unit, configured to inverse multiplex said translated predetermined data.
13. The apparatus of claim 12 wherein said encoded data includes 8B/10B encoded data.
14. The apparatus of claim 13 wherein said encoded data includes one of a Gigabit Ethernet data and a Fiber Channel data.
15. The apparatus of claim 12 wherein said clock recovery unit is further configured to detect a data rate of said received encoded data.
16. The apparatus of claim 15 wherein said clock recovery unit is further configured to recover a clock signal from said received encoded data.
17. The apparatus of claim 16 wherein said clock signal has a rate one tenth of said data rate.
18. The apparatus of claim 12 wherein predetermined data includes a 9-bit data.
19. The apparatus of claim 18 wherein said 9-bit data includes one of an arbitrary set of 9-bit data.
20. The apparatus of claim 12 wherein said inverse multiplexer is further configured to synchronize said multiplexed predetermined data to a predetermined clock signal.
21. The apparatus of claim 20 wherein said predetermined clock signal includes a phase locked loop clock signal.
22. The apparatus of claim 12 further including a modem coupled to said inverse multiplexer configured to receive said inverse multiplexed translated predetermined data for transmission.
23. The apparatus of claim 22 wherein said inverse multiplexed translated predetermined data includes a plurality of STS-3 signals.
24. The apparatus of claim 23 wherein said plurality of STS-3 signals includes eight STS-3 signals for transmission.
25. An apparatus for providing data transport in a network, comprising:
- a demultiplexer configured to demultiplex received data;
- a data translation unit coupled to said multiplexer configured to translate said demultiplexed data to a predetermined data; and
- a serializer coupled to said data translation unit configured to receive said translated predetermined data and accordingly to generate a corresponding encoded data.
26. The apparatus of claim 25 wherein said received data includes a plurality of STS-3 signals.
27. The apparatus of claim 26 wherein said plurality of STS-3 signals includes eight STS-3 signals.
28. The apparatus of claim 26 further including a plurality of FIFOs each configured to frame align said each of STS-3 signals, said frame aligned STS-3 signals corresponding to said received signal.
29. The apparatus of claim 25 wherein said demultiplexed data includes a 9-bit data.
30. The apparatus of claim 29 wherein said 9-bit data has a data rate of 1,125 Mbits/second.
31. The apparatus of claim 29 wherein said demultiplexer is further configured to perform parity checks on said received data.
32. The apparatus of claim 25 wherein said predetermined data includes a 10-bit data.
33. The apparatus of claim 25 wherein said serializer is configured to synchronize the translated predetermined data.
34. The apparatus of claim 33 wherein said translated predetermined data includes a 10-bit data.
35. The apparatus of claim 34 wherein said 10-bit data has a data rate of 1,250 Mbits/second.
36. The apparatus of claim 35 wherein said encoded data includes an 8B/10B encoded data.
37. A method for providing data transport in a network, comprising the steps of:
- demultiplexing a received data;
- translating said demultiplexed data to a predetermined data; and
- generating a corresponding encoded data based on said translated predetermined data.
38. The method of claim 37 wherein said received data includes a plurality of STS-3 signals.
39. The method of claim 38 wherein said plurality of STS-3 signals includes eight STS-3 signals.
40. The method of claim 38 further including the step of frame aligning said each of STS-3 signals, said frame aligned STS-3 signals corresponding to said received data for demultiplexing.
41. The method of claim 37 wherein said demultiplexed data includes a 9-bit data.
42. The method of claim 41 wherein said 9-bit data has a data rate of 1,125 Mbits/second.
43. The method of claim 41 further including the step of performing parity checks on said received data.
44. The method of claim 37 wherein said predetermined data includes a 10-bit data.
45. The method of claim 37 further including the step of synchronizing the translated predetermined data.
46. The method of claim 45 wherein said translated predetermined data includes a 10-bit data.
47. The method of claim 46 wherein said 10-bit data has a data rate of 1,250 Mbits/second.
48. The method of claim 47 wherein said encoded data includes an 8B/10B encoded data.
Type: Application
Filed: Dec 21, 2007
Publication Date: Jul 10, 2008
Inventors: Anthony William Jorgenson (Fremont, CA), Nicholas Joseph Possley (Gilroy, CA)
Application Number: 11/963,291
International Classification: G01R 31/08 (20060101);