# Patent

## Title
System, method, and article of manufacture for initializing a communication link using GFP data frames

## Abstract

A system and a method for initializing a communication link for transmitting a data stream from a first computer through a synchronous optical communication network to a second computer are provided. The method includes transmitting a first request message in a first GFP data frame to a second computer. The method further includes transmitting a second acknowledgement message in a second GFP data frame from the second computer to the first computer. The method further includes initializing the communication link between the first computer and the second computer in response to the acknowledgement message.

## Background
FIELD OF INVENTION
The invention relates to a system, method, and an article of manufacture for initializing a communication link using GFP data frames.
BACKGROUND OF INVENTION
The Generic Framing Procedure (GFP) is a communication standard that defines a procedure for encapsulating and delineating variable-length payloads from received data message for transporting the data messages over a synchronous optical communication network (SONET). Systems implementing the GFP communication standard, however, do not validate that a communication link has been established between first and second computers prior to sending data frames between the first and second computers. Accordingly, when the first computer initially transmits a data frame through the SONET communication network to a second computer and the second computer is not operable or not ready to receive the data frame, the data frame is not received and stored by the second computer.
Accordingly, there is a need for a system and a method for initializing a communication link through a synchronous optical communication network by validating that a downstream computer is ready to receive a data stream.
SUMMARY OF INVENTION
A method for initializing a communication link for transmitting a data stream from a first computer through a synchronous optical communication network to a second computer in accordance with exemplary embodiment is provided. The method includes transmitting a first request message at a first time from the first computer to a first GFP data mapping device. The method further includes generating a first GFP data frame based on the first request message using the first GFP data mapping device that indicates that the communication link is being requested, and transmitting the first GFP data frame through the synchronous optical communication network to a second GFP demapping device. The method further includes decoding the first GFP data frame to obtain the first request message and transmitting the first request message from the second GFP demapping device to the second computer. The method further includes generating a second acknowledgement message using the second computer in response to the first request message and transmitting the first request message to a third GFP data mapping device. The method further includes generating a second GFP data frame based on the second acknowledgement message using the third GFP data mapping device and transmitting the second GFP data frame through the synchronous optical communication network to a fourth GFP demapping device. The method further includes decoding the second GFP data frame at a second time using the fourth GFP demapping device to obtain the second acknowledgement message. The method further includes initializing the communication link between the first computer and the second computer in response to the acknowledgement message.
A system for initializing a communication link through a synchronous optical communication network in accordance with another exemplary embodiment is provided. The system includes a first computer configured to generate a first request message at a first time. The system further includes a first GFP data mapping device configured to receive the first request message and to generate a first GFP data frame based on the first request message that indicates that the communication link is being requested. The first GFP data mapping device is further configured to transmit the first GFP data frame through the synchronous optical communication network. The system further includes a second GFP data mapping device configured to receive the first GFP data frame to decode the first GFP data frame to obtain the first request message. The system further includes a second computer configured to receive the first request message from the second GFP data mapping device and to generate a second acknowledgement message in response to the first request message. The system further includes a third GFP data mapping device configured to receive the second acknowledgement message and to generate a second GFP data frame based on the second acknowledgement message. The third GFP data mapping device is further configured to transmit the second GFP data frame through the synchronous optical communication network. The system further includes a fourth GFP data demapping device configured to receive the second GFP data frame and to decode the second GFP data frame at a second time to obtain the second acknowledgement message. The first GFP mapping device is further configured to initialize the communication link between the first computer and the second computer in response to the fourth GFP data demapping device receiving the second acknowledgement message.
An article of manufacture in accordance with another exemplary embodiment is provided. The article of manufacture includes a computer storage medium having a computer program encoded therein for initializing a communication link for transmitting a data stream from a first computer through a synchronous optical communication network to a second computer. The computer storage medium includes code for transmitting a first request message at a first time from the first computer to a first GFP data mapping device. The computer storage medium further includes code for generating a first GFP data frame based on the first request message using the first GFP data mapping device that indicates that the communication link is being requested, and transmitting the first GFP data frame through the synchronous optical communication network to a second GFP demapping device. The computer storage medium further includes code for decoding the first GFP data frame to obtain the first request message and transmitting the first request message from the second GFP demapping device to the second computer. The computer storage medium further includes code for generating a second acknowledgement message using the second computer in response to the first request message and transmitting the first request message to a third GFP data mapping device. The computer storage medium further includes code for generating a second GFP data frame based on the second acknowledgement message using the third GFP data mapping device and transmitting the second GFP data frame through the synchronous optical communication network to a fourth GFP demapping device. The computer storage medium further includes code for decoding the second GFP data frame at a second time using the fourth GFP demapping device to obtain the second acknowledgement message. The computer storage medium further includes code for initializing the communication link between the first computer and the second computer in response to the acknowledgement message.
Other systems, methods and/or computer program products according to the embodiments will be or become apparent to one with skill in the art upon review of the following drawings and detailed description. It is intended that at all such additional systems, methods, and/or computer program products be within the scope of the present invention, and be protected by the accompanying claims.



BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a block diagram of a communication system for initializing a communication link in accordance with an exemplary embodiment;
FIG. 2 is a block diagram of a GFP data frame having a request message;
FIG. 3 is a block diagram of a GFP data frame having an acknowledgment message; and
FIGS. 4-5 are flowcharts of a method for initializing a communication link in accordance with another exemplary embodiment.



DESCRIPTION OF AN EMBODIMENT
Referring to FIG. 1, a communication system 10 for initializing a communication link using GFP data frames is illustrated. In an exemplary embodiment, the communication system 10 utilizes an open fiber control methodology to obtain a communication link that provides an exclusive communication connection for a duration of a session between computers 12, 24. Further, the communication link comprises a Class 1 communication link, in an exemplary embodiment. The open fiber control methodology is a handshaking protocol that is used to verify that duplex fiber optic cables are properly connected to the computers 12, 24, respectively, prior to transmitting data between the computers 12, 24. Of course, the methodology described below could also be utilized with other systems that utilize transmission means other than fiber optic cables. The system 10 includes a computer 12, fiber optic cables 13, 15, a GFP data mapping device 14, a GFP data demapping device 16, a SONET communication network 18, a GFP data demapping device 20, a GFP data mapping device 22, fiber optic cables 21, 23, and a computer 24.
The computer 12 is provided to generate a request message at a first time that requests a communication link be initialized between the computer 12 and the computer 24 prior to sending a data stream therebetween. The request message is communicated through the fiber optic cable 13, the GFP data mapping device 14, the SONET communication network 18, the fiber optic cable 21, and the GFP data demapping device 20 to the computer 24. As shown, the computer 12 operably communicates with: (i) the GFP data mapping device 14 via the fiber optic cable 13, and (ii) the GFP data demapping device 16 via the fiber optic cable 15.
Referring to FIGS. 1 and 2, the GFP data mapping device 14 is provided to receive the request message and to generate a GFP data frame 40 based on the request message that indicates a communication link is being requested. The GFP data mapping device 14 is further configured to transmit the GFP data frame 40 through the SONET communication network 18 to the GFP data demapping device 20. The GFP data frame 40 includes a payload type identifier and a user payload identification value. In particular, the payload type identifier is specified by the bit sequence “100” and the user payload identification value is specified as the bit sequence “00000011”. The GFP data mapping device 14 is further configured to send a first acknowledgment message to the computer 12 in response to the request message. In an alternate embodiment, the GFP data mapping device 14 and the GFP data demapping device 16 can comprise one device having a data mapping module and a data demapping module, respectively.
The SONET communication network 18 is provided to transmit GFP frames from the GFP data mapping device 14 to the GFP data demapping device 20. Further, the SONET communication network 18 is provided to transmit GFP frames from the GFP data mapping device 22 to the GFP data demapping device 16.
Referring to FIGS. 1 and 3, the GFP data demapping device 20 is provided to decode the GFP data frame 40 to obtain the request message and to transmit the request message to the computer 24. The GFP data demapping device 20 operably communicates with the SONET communication network 18, and to the computer 24 via the fiber optic cable 21.
The computer 24 is provided to receive the request message and to generate a second acknowledgment message in response to the request message. The computer 24 is further configured to transmit the second acknowledgment message to the GFP data mapping device 22. As shown, the computer 24 is operably coupled to: (i) the GFP data demapping device 20 via the fiber optic cable 21, and (ii) the GFP data mapping device 22 via the fiber optic cable 23.
Referring to FIGS. 1 and 2, the GFP data mapping device 22 is provided to receive the acknowledgment message from the computer 24 and to generate a GFP data frame 42 based on the second acknowledgment message that indicates that the computer 24 is ready to receive data from the computer 12. The GFP data mapping device 22 is further configured to transmit the GFP data frame 42 through the SONET communication network 18 to the GFP data demapping device 16. The GFP data frame 42 includes a payload type identifier and a user payload identification value. In particular, the payload type identifier is specified by the bit sequence “100” and the user payload identification value is specified as the bit sequence “00000101”. In an alternate embodiment, the GFP data mapping device 22 and the GFP data demapping device 20 can comprise one device having a data mapping module and a data demapping module, respectively.
Referring to FIG. 1, the GFP data demapping device 16 is provided to decode the GFP data frame 40 at a second time to obtain the second acknowledgment message and to transmit the second acknowledgment message to the computer 12. The GFP data mapping device 14 is configured to transmit data from the computer 12 through the SONET communication network 18 to the computer 24, when a time difference between a first time when the request message was transmitted from the computer 12 and a second time when the GFP data frame 40 is received by the device 16, is less than a threshold time interval.
Referring to FIGS. 4-5, a method for initializing a communication link between the computer 12 and the computer 24 will now be explained. The method is implemented utilizing the system 10.
At step 60, the computer 12 transmits a request message at a first time to the GFP data mapping device 14.
At step 62, the GFP data mapping device 14 generates a first acknowledgement message and transmits the first acknowledgment message to the computer 12. Further, the device 14 starts a timer (not shown) therein.
At step 64, the GFP data mapping device 14 generates a GFP data frame 40 based on the request message and transmits the GFP data frame 40 through the SONET communication network 18 to the GFP demapping device 20.
At step 66, the GFP data demapping device 20 decodes the GFP data frame 40 to obtain the request message and transmits the request message to the computer 24.
At step 68, the computer 24 generates a second acknowledgement message in response to the request message and transmits the second acknowledgement message to the GFP data mapping device 22.
At step 70, the GFP data mapping device 22 generates a GFP data frame 42 based on the second acknowledgement message and transmits the GFP data frame 42 through the SONET communication network to the GFP data demapping device 16.
At step 72, the GFP data demapping device 16 decodes the GFP data frame 42 at a second time to obtain the second acknowledgement message.
At step 74, the GFP data demapping device 16 makes determination as to whether a time difference between the first time and the second time is less than or equal to a threshold time interval. The device 16 determines the time difference by obtaining a time value from the timer (not shown) therein. If the value of step 74 equals “yes”, the method advances to step 76. Otherwise, the timer is reset and the method advances to step 60.
At step 76, the GFP mapping device 14 initializes the communication link between the computer 12 and the computer 24 in response to the GFP data demapping device 16 receiving the second acknowledgement message.
At step 78, the computer 12 transmits a first data stream utilizing the communication link through the SONET communication network to the computer 24. After step 78, the method is exited.
The system and the method for initializing a communication link for transmitting a data stream from a first computer through a SONET communication network to a second computer provide a substantial advantage over other systems and methods. In particular, the system and the method provide a technical effect of transmitting a request message and an acknowledgment message to validate that the second computer is ready to receive a data stream.
While the invention is described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made an equivalence may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to the teachings of the invention to adapt to a particular situation without departing from the scope thereof. Therefore, is intended that the invention not be limited the embodiment disclosed for carrying out this invention, but that the invention includes all embodiments falling with the scope of the intended claims. Moreover, the use of the term's first, second, etc. does not denote any order of importance, but rather the term's first, second, etc. are us are used to distinguish one element from another.

## Claims

1. A method for initializing a communication link for transmitting a data stream from a first computer through a synchronous optical communication network to a second computer, comprising:
transmitting a first request message at a first time from the first computer to a first GFP data mapping device;
generating a first GFP data frame based on the first request message using the first GFP data mapping device that indicates that the communication link is being requested, and transmitting the first GFP data frame through the synchronous optical communication network to a second GFP demapping device;
decoding the first GFP data frame to obtain the first request message and transmitting the first request message from the second GFP demapping device to the second computer;
generating a second acknowledgement message using the second computer in response to the first request message and transmitting the first request message to a third GFP data mapping device;
generating a second GFP data frame based on the second acknowledgement message using the third GFP data mapping device and transmitting the second GFP data frame through the synchronous optical communication network to a fourth GFP demapping device;
decoding the second GFP data frame at a second time using the fourth GFP demapping device to obtain the second acknowledgement message; and
initializing the communication link between the first computer and the second computer in response to the acknowledgement message.

2. The method of claim 1, wherein the step of initializing the communication link between the first computer and the second computer in response to the acknowledgement message comprises:
selecting an exclusive communication link using the first GFP data mapping device for communicating the data stream from the first computer through the synchronous optical communication network to the second computer.

3. The method of claim 1, wherein the step of initializing the communication link between the first computer and the second computer occurs when a time difference between the first time and the second time is less than or equal to a threshold time interval.

4. The method of claim 1, further comprising:
transmitting a first data stream from the first computer through the synchronous optical communication network to the second computer, in response to the initialization of the communication link.

5. The method of claim 4, wherein the first data stream comprises an ISC data stream.

6. The method of claim 3, further comprising:
transmitting a second data stream from the second computer through the synchronous optical communication network to the first computer, in response to the initialization of the communication link.

7. The method of claim 1, further comprising:
generating a third acknowledgement message at a third time in response to the first GFP data mapping device receiving the first request message and transmitting the third acknowledgement message from the first GFP data mapping device to the first computer.

8. The method of claim 7, further comprising stopping data communication between the first computer and the first GFP data mapping device when a time difference between the first time and the third time is greater than a threshold time period.

9. A system for initializing a communication link through a synchronous optical communication network, comprising:
a first computer configured to generate a first request message at a first time;
a first GFP data mapping device configured to receive the first request message and to generate a first GFP data frame based on the first request message that indicates that the communication link is being requested, the first GFP data mapping device being further configured to transmit the first GFP data frame through the synchronous optical communication network;
a second GFP data mapping device configured to receive the first GFP data frame to decode the first GFP data frame to obtain the first request message;
a second computer configured to receive the first request message from the second GFP data mapping device and to generate a second acknowledgement message in response to the first request message;
a third GFP data mapping device configured to receive the second acknowledgement message and to generate a second GFP data frame based on the second acknowledgement message, the third GFP data mapping device further configured to transmit the second GFP data frame through the synchronous optical communication network;
a fourth GFP data demapping device configured to receive the second GFP data frame and to decode the second GFP data frame at a second time to obtain the second acknowledgement message; and
the first GFP mapping device being further configured to initialize the communication link between the first computer and the second computer in response to the fourth GFP data demapping device receiving the second acknowledgement message.

10. The system of claim 9, wherein the first GFP mapping device is configured to initialize the communication link between the first computer and the second computer by
selecting an exclusive communication link from the first computer through the synchronous optical communication network to the second computer.

11. The system of claim 9, wherein the initialization of the communication link between the first computer and the second computer occurs when a time difference between the first time and the second time is less than or equal to a threshold time interval.

12. The system of claim 9, wherein the first computer is further configured to transmit
a first data stream through the synchronous optical communication network to the second computer, in response to the initialization of the communication link.

13. The system of claim 12, wherein the first data stream comprises an ISC data stream.

14. The system of claim 12, wherein the second computer is further configured to transmit a second data stream through the synchronous optical communication network to the first computer, in response to the initialization of the communication link.

15. The system of claim 9, wherein the first GFP data mapping device is further configured to generate a third acknowledgement message at a third time in response to the first GFP data mapping device receiving the first request message, the first GFP data mapping device being further configured to transmit the third acknowledgement message to the first computer.

16. The system of claim 9, wherein the first GFP data mapping device is further configured to stop data communication between the first GFP data mapping device and the first computer when a time difference between the first time and the third time is greater than a threshold time period.

17. An article of manufacture, comprising:
a computer storage medium having a computer program encoded therein for initializing a communication link for transmitting a data stream from a first computer through a synchronous optical communication network to a second computer, the computer storage medium including:
code for transmitting a first request message at a first time from the first computer to a first GFP data mapping device;
code for generating a first GFP data frame based on the first request message using the first GFP data mapping device that indicates that the communication link is being requested, and transmitting the first GFP data frame through the synchronous optical communication network to a second GFP demapping device;
code for decoding the first GFP data frame to obtain the first request message and transmitting the first request message from the second GFP demapping device to the second computer;
code for generating a second acknowledgement message using the second computer in response to the first request message and transmitting the first request message to a third GFP data mapping device;
code for generating a second GFP data frame based on the second acknowledgement message using the third GFP data mapping device and transmitting the second GFP data frame through the synchronous optical communication network to a fourth GFP demapping device;
code for decoding the second GFP data frame at a second time using the fourth GFP demapping device to obtain the second acknowledgement message; and
code for initializing the communication link between the first computer and the second computer in response to the acknowledgement message.