Method for flow control in asymmetric digital subscriber line devices

• US 6,542,465 B1
• Filed: 05/28/1999
• Issued: 04/01/2003
• Est. Priority Date: 05/28/1999
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: 3Com Corporation (HP Inc.)
• Inventors: Wang, Ray
• Primary Examiner(s): Kizou, Hassan
• Assistant Examiner(s): ODLAND, DAVID E
• Application Number:
  US09/322,575
• Time in Patent Office: 1,404 Days
• Field of Search: 370/229, 370/230, 370/230.1, 370/231, 370/232, 370/233, 370/235, 370/235.1, 370/236, 370/395.1, 370/395.2, 370/395.21, 370/395.43, 370/395.71, 370/485, 375/219, 375/220, 375/222, 379/93.01, 379/93.08
• US Class Current: 370/232
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 12/2801 Broadband local area networks
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/11 Identifying congestion
• CPC Class Codes: H04L 47/193 at the transport layer, e.g. TCP related
• CPC Class Codes: H04L 47/263 Rate modification at the source after receiving feedback
• CPC Class Codes: H04L 5/1446 of transmission speed

Abstract

A method for flow control in asymmetric digital subscriber line (“ADSL”) devices. The method includes flow control that adapts to changes in line conditions such as noise signals, onhook/offhook signals, etc. that may result in degradations in the quality-of-service in an ADSL system. The flow control includes buffering outbound data and ceasing transmission of data at an original transmission rate on an ADSL device that is used on a customer site. An original data transmission rate is adjusted based on changes in line conditions. One more or data transmission characteristics may be adjusted before sending any data at a new data transmission rate. For example, Asynchronous Transport Mode (“ATM”) often uses ADSL devices as a physical layer to transmit data. ATM available bit-rate, constant bit-rate, variable bit-rate or unspecified bit-rate transmission characteristics or ATM quality-of -service characteristics may be adjusted before sending any data at a new data transmission rate. Traffic shaping may be optionally applied to the data at the new data transmission rate. The method may be especially useful for maintaining a quality-of-service transmission at a lower transmission rate, using splitterless ADSLs, or “Lite ADSL” (e.g., G.lite).

Claims

1. A method for flow control in an asymmetric data transmission system, comprising the steps of:

detecting a change on a first asymmetric network device on a connection between the first asymmetric network device and a second asymmetric network device in an asymmetric data transmission system, wherein data is transmitted at a higher data rate in downstream direction, than in an upstream direction on the asymmetric data system, and wherein data is being transmitted on the connection between the first asymmetric network device and the second asymmetric network device at a first data transmission rate;

starting a data rate adaptation procedure on the first asymmetric network device to adapt the first data transmission rate based on the changed condition on the connection;

invoking a flow control procedure on the first asymmetric network device, wherein the flow control procedure includes buffering outbound data and notifying an application layer on the first asymmetric network device to temporarily cease data transmission at the first data transmission rate;

negotiating a second data transmission rate on the connection between the first asymmetric network device and the second asymmetric network device based on the change on the connection; and

adjusting the data transmission rate on the first asymmetric network device to use the second data transmission rate on the connection between the first asymmetric network device and the second asymmetric network device, wherein adjusting the data transmission rate includes notifying the application layer on the first asymmetric network device to resume data transmission at the second data transmission rate.

2. A computer readable medium having stored therein instructions for causing a central processing unit to execute the method of claim 1.

3. The method of claim 1 wherein the asymmetric data transmission system is an Asymmetric Digital Subscriber Line system including asymmetric network devices compliant with all or part of any of the International Telephone Union G.922.1 standard or the American National Standards Institute T1.413 standard.

4. The method of claim 1 wherein the asymmetric data transmission system is a spliterless Asymmetric Digital Subscriber Line system including asymmetric network devices compliant with all or part of the International Telephone Union G.922.2 (G.lite) standard.

5. The method of claim 1 wherein the first asymmetric network device is an Asymmetric Digital Subscriber Line ATU-R network device.

6. The method of claim 1 wherein the second asymmetric network device is an Asymmetric Digital Subscriber Line ATU-C network device.

7. The method of claim 1 wherein the step of detecting a change on a first asymmetric network device on a connection includes detecting any of a noise signal, an on-hook signal, an off-hook signal, or a ringing-signal on the connection.

8. The method of claim 1 wherein the step of adjusting the data transmission rate on the first asymmetric network device to use the second data transmission rate on the connection includes:

determining whether the second data transmission rate is faster than a peak data rate, and if so,

notifying the application layer on the first asymmetric network device to resume data transmission at the second data transmission rate without changing data transmission characteristics used for the first data transmission rate.

9. The method of claim 8 wherein the peak data rate is a peak cell rate used for Asynchronous Transfer Mode cell transmission on the connection.

10. The method of claim 1 wherein the step of adjusting the data transmission rate on the first asymmetric network device to use the second data transmission rate on the connection includes:

determining whether the second data transmission rate is slower than the first data transmission rate, and if so,

notifying the application layer on the first asymmetric network device to change one or more data transmission characteristics used for the first data transmission rate before transmitting any data at the second data transmission rate.

11. The method of claim 10 wherein the data transmission characteristics used for the first transmission rate include any of available bit-rate characteristics, unspecified bit-rate characteristics, variable bit-rate characteristics, or constant bit-rate characteristics used for used for Asynchronous Transfer Mode cell transmission on the connection.

12. A method for flow control in an asymmetric data transmission system, comprising the steps of:

detecting a change on an asymmetric digital subscriber line ATU-R device on a connection between the asymmetric digital subscriber line ATU-R device and an asymmetric digital subscriber line ATU-C device in an asymmetric data transmission system, wherein data is transmitted at a higher data rate in downstream direction, than in an upstream direction on the asymmetric data system, and wherein data is being transmitted on the connection between the asymmetric digital subscriber line ATU-R device and the asymmetric digital subscriber line ATU-C device at a first data transmission rate;

starting a data rate adaptation procedure on the asymmetric digital subscriber line ATU-R device to adapt the first data transmission rate based on the changed condition on the connection;

invoking a flow control procedure on the asymmetric digital subscriber line ATU-R device, wherein the flow control procedure includes buffering outbound data and notifying an application layer on the asymmetric digital subscriber line ATU-R device to temporarily cease data transmission at the first data transmission rate;

negotiating a second data transmission rate on the connection between the asymmetric digital subscriber line ATU-R device and the asymmetric digital subscriber line ATU-C device based on the change on the connection;

determining whether the second data transmission rate is faster than a peak data rate, and if so,

notifying the application layer on the asymmetric digital subscriber line ATU-R device to resume data transmission at the second data transmission rate without changing data transmission characteristics used for the first data transmission rate, and if not,

determining whether the second data transmission rate is slower than the first data transmission rate, and if so,

notifying the application layer on the asymmetric digital subscriber line ATU-R asymmetric network device to change one or more data transmission characteristics used for the first data transmission rate before transmitting any data at the second data transmission rate.

13. A computer readable medium having stored therein instructions for causing a central processing unit to execute the method of claim 12.

14. The method of claim 12 wherein the asymmetric data transmission system is an Asymmetric Digital Subscriber Line system including asymmetric network devices compliant with all or part of any of the International Telephone Union G.922.1 standard or the American National Standards Institute T1.413 standard.

15. The method of claim 12 wherein the asymmetric data transmission system is a spliterless Asymmetric Digital Subscriber Line system compliant with all or part of the International Telephone Union G.922.2 (G.lite) standard.

16. The method of claim 12 wherein the step of starting a procedure on the asymmetric digital subscriber line ATU-R device to adapt the first data transmission rate based on the changed condition on the asymmetric digital subscriber line connection includes starting an asymmetric digital subscriber line fast retrain procedure.

17. The method of claim 12 wherein the step of determining whether the second data transmission rate is faster than a peak data rate includes determining if the second data transmission rate is faster than a peak cell rate used for Asynchronous Transfer Mode cell transmission on the connection.

18. The method of claim 12 wherein the step of determining whether the second data transmission rate is slower than the first data transmission rate includes determining if the second data transmission rate is slower than a current cell rate used for Asynchronous Transfer Mode cell transmission on the connection.

19. The method of claim 12 wherein the step of notifying the application layer on the asymmetric digital subscriber line ATU-R device to change one or more data transmission characteristics used for the first data transmission rate before transmitting any data at the second data transmission rate includes changing one or more data transmission characteristics used for any of available bit-rate characteristics, unspecified bit-rate characteristics, variable bit-rate characteristics, or constant bit-rate characteristics used for used for Asynchronous Transfer Mode cell transmission on the connection.

20. The method of claim 12 wherein the step of notifying the application layer on the asymmetric digital subscriber line ATU-R to change one or more data transmission characteristics used for the first data transmission rate before transmitting any data at the second data transmission rate includes changing Asynchronous Transfer Mode available bit-rate characteristics by:

determining whether the second data transmission rate is between a peak and a minimum cell data transmission rate, and if so,

adjusting an Asynchronous Transfer Mode egress cell data transmission rate to the second data transmission rate; and

if not,

determining whether the second data transmission rate is below the minimum cell data transmission rate, and if so,

setting the peak and minimum cell data transmission rates equal to the second data transmission rate; and

optionally performing traffic shaping on cells transmitted at the second data transmission rate.

21. The method of claim 12 wherein the step of notifying the application layer on the asymmetric digital subscriber line ATU-R device to change one or more data transmission characteristics used for the first data transmission rate before transmitting any data at the second data transmission rate includes changing Asynchronous Transfer Mode unspecified bit-rate characteristics by:

setting a peak cell data transmission rate to be less than or equal to the second data transmission rate; and

optionally performing traffic shaping on cells transmitted at the second data transmission rate.

22. The method of claim 12 wherein the step of notifying the application layer on the asymmetric digital subscriber line ATU-R device to change one or more data transmission characteristics used for the first data transmission rate before transmitting any data at the second data transmission rate includes changing Asynchronous Transfer Mode variable bit-rate characteristics by:

notifying the application layer that a Asynchronous Transfer Mode Quality-of-Service is being violated;

determining whether the application layer desires to continue cell data transmission at the second data transmission rate, and if so,

performing traffic shaping upstream from the asymmetric digital subscriber line ATU-R device to the asymmetric digital subscriber line ATU-C device on the cells transmitted at the second data transmission rate; and

if not,

terminating data transmission on the connection.

23. The method of claim 12 wherein the step of notifying the application layer on the asymmetric digital subscriber line ATU-R device to change one or more data transmission characteristics used for the first data transmission rate before transmitting any data at the second data transmission rate includes changing Asynchronous Transfer Mode constant bit-rate characteristics by:

notifying the application layer that an ATM Quality-of-Service is being violated; and

terminating data transmission on the connection.