Method and apparatus for managing control messages in a communication system

• US 6,240,067 B1
• Filed: 10/06/1997
• Issued: 05/29/2001
• Est. Priority Date: 10/06/1997
• Status: Expired due to Term

• Current Assignee: Ericsson Messaging Systems Incorporated (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Ericsson Messaging Systems Incorporated (Telefonaktiebolaget LM Ericsson)
• Inventors: Sorber, Gordon P.
• Primary Examiner(s): Nguyen, Chau
• Assistant Examiner(s): BOAKYE, ALEXANDER O
• Application Number:
  US08/944,765
• Time in Patent Office: 1,331 Days
• Field of Search: 370/216, 370/235, 370/241, 370/229, 370/242, 370/244, 370/250, 370/252, 370/410, 370/384, 370/385, 370/522, 370/236, 395/550, 395/183.02
• US Class Current: 370/236
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/2416 Real-time traffic
• CPC Class Codes: H04L 47/2433 Allocation of priorities to traffic types
• CPC Class Codes: H04L 47/2466 using signalling traffic
• CPC Class Codes: H04L 47/32 by discarding or delaying data units, e.g. packets or frames
• CPC Class Codes: H04L 47/33 using forward notification

Abstract

The present invention provides an auto-cancelling buffer and method that ensures that time sensitive control messages such as congestion alarms and recovery messages are efficiently moved between control processes. In a general embodiment, one or more time sensitive control messages are stored in a special buffer. A current control message indicating a first state is compared with a previously buffered control message. If the buffered control message is in a second different state, e.g., opposite the first state, the buffered control message is removed from the buffer, and both messages are discarded. In effect, opposing control messages are cancelled rather than both stored in the buffer. This avoids unnecessary cycling of an end process which acts on control messages forwarded from the buffer. For example, if the control messages include congestion alarm messages and congestion recovery messages, one of the congestion alarm and recovery messages previously stored in the buffer is automatically cancelled when the other message is received. If the compared messages have the same states, only one is stored in the buffer.

Claims

1. A method for managing control messages, comprising the steps of:

storing a control message in a buffer;

receiving a current control message indicating a first state;

comparing the current control message with the buffered control message; and

if the buffered control message is in a second state different from the first state, removing the buffered control message from the buffer,

wherein the control message in the first state is one of a congestion alarm and a congestion recovery alarm and in the second state is the other of the congestion alarm and the congestion recovery alarm.

2. The method in claim 1, further comprising:

discarding the buffered control message and the current control message.

3. The method in claim 1, further comprising:

if the states of the buffered and current control message match, discarding one of the control messages and storing the other in the buffer.

4. The method in claim 1, further comprising:

generating control messages for different control levels;

storing a corresponding control message in the buffer for each control level;

determining a control level of the current control message; and

removing a buffered control message from the buffer having the same level as the current control message when a state of that buffered control message having the same level and a state of the current control message are different.

5. The method in claim 4, further comprising:

removing another buffered control message from the buffer at a control level other than the same level when the buffered control message having the same level as the current control message is removed.

6. The method in claim 5, wherein the another buffered control message is at a higher control level other than the same level.

7. The method in claim 5, wherein the another buffered control message is at a lower control level than the same level.

8. A method for use in a communications system, comprising:

receiving one or more congestion alarm messages,

receiving one or more congestion recovery messages;

storing one of the congestion alarm and congestion recovery messages in a buffer;

automatically canceling the buffered message when the other of the congestion alarm and congestion recovery messages is received; and

discarding the buffered message and the canceled message.

9. The method in claim 8, further comprising:

when a new congestion recovery message is received, storing the new congestion recovery message in the buffer and discarding a congestion alarm message stored in the buffer, and

when a new congestion alarm message is received, storing the new congestion alarm message in the buffer and discarding a congestion recovery message stored in the buffer.

10. The method in claim 8, wherein congestion alarm messages and congestion recovery messages are assigned to different priority levels.

11. The method in claim 10, wherein when the buffer stores a congestion alarm message for one of the priority levels, lower priority levels are assumed to be congested and higher priority levels are assumed to be not congested such that when a congestion recovery message is received corresponding to the one priority level, congestion alarm messages stored for the one priority level and higher are canceled.

12. The method in claim 11, wherein the received congestion recovery message is stored in the buffer.

13. The method in claim 10, wherein when the buffer stores a congestion recovery message for one of the priority levels, lower level priorities are assumed to be congested and higher priority levels are assumed to be not congested such that when a congestion alarm message is received corresponding to the one priority level, congestion recovery messages stored for the one priority level and lower are canceled.

14. The method in claim 13, wherein the received congestion alarm message is stored in the buffer.

15. A data transmission interface, comprising:

a buffer storing control messages having a first state and a second state, and

a controller managing control messages received for storage in the buffer,

wherein the controller cancels one of the control messages stored in the buffer having the first state when a subsequent control message in the second state is received.

16. The data transmission interface according to claim 15, wherein the buffer stores time sensitive information, the data transmission interface further comprising:

a first-in-first-out (FIFO) buffer, in addition to the control message buffer, storing messages containing information other than the time sensitive information.

17. The data transmission interface in claim 15, wherein the controller discards the subsequent control message if the states of the one and the subsequent control messages match.

18. The data transmission interface in claim 15, wherein the control message in the first state is a congestion alarm and in the second state is a congestion recovery alarm.

19. The data transmission interface in claim 15, wherein the control message in the first state is a congestion recovery alarm and in the second state is a congestion alarm.

20. The data transmission interface in claim 15, wherein control messages are generated for different control levels with corresponding control messages being stored in the buffer for each control level in a linked list structure.

21. The data transmission interface in claim 20, wherein the controller determines a control level of the subsequent control message, and removes a buffered control message having the same level as the current control message from the linked list when the state of the buffered control message having the same level and the subsequent control messages are different.

22. Apparatus comprising:

plural transmit buffers, each transmit buffer having a corresponding priority level and storing messages with the corresponding priority level to be transmitted over a transmission link, where congestion control messages relating to a congestion status of each transmit buffer are generated for each transmit buffer;

a congestion message buffer storing congestion messages relating to each transmit buffer; and

a controller determining the priority level and state of a newly-generated congestion message, and if the determined state of the newly-generated congestion message is different than the state of a congestion message at the determined level already stored in the congestion message buffer, the controller cancels the already stored congestion message.

23. The apparatus in claim 22, wherein the controller discards both the newly-generated and the already stored congestion messages having different states.

24. The apparatus in claim 22, wherein the controller assigns a congestion alarm message and a congestion recovery message to different priority levels.

25. The apparatus in claim 24, wherein when the congestion message buffer stores a congestion alarm message for one of the priority levels, lower priority levels are assumed to be congested and higher priority levels are assumed to be not congested such that when a congestion recovery message is received corresponding to the one priority level, the controller cancels congestion alarm messages stored for the one priority level and higher.

26. The apparatus in claim 25, wherein the controller stores the received congestion recovery message in the congestion message buffer.

27. The apparatus in claim 24, wherein when the congestion message buffer stores a congestion recovery message for one of the priority levels, lower level priorities are assumed to be congested and higher priority levels are assumed to be not congested such that when a congestion alarm message is received corresponding to the one priority level, the controller cancels congestion recovery messages stored for the one priority level and lower.

28. The apparatus in claim 27, wherein the controller stores the received congestion alarm message in the congestion message buffer.

29. The apparatus in claim 22, further comprising:

a first-in-first-out (FIFO) buffer for storing messages from the controller other than congestion messages.

30. A data transmission interface, comprising:

a first buffer storing first control messages of a first type including time sensitive congestion alarm and recovery messages;

a second buffer storing second control messages of a second type different than the first type control messages; and

a controller analyzing received control messages and selectively storing the first type control messages in the first buffer and the second type control messages in the second buffer,

wherein the controller does not store redundant, first type control messages in the first buffer.

31. The data transmission interface according to claim 30, wherein the first type corresponds to a first priority and the second type corresponds to a second priority lower than the first priority and the controller selectively transmits control messages stored in the first buffer before transmitting control messages in the second buffer.

32. The data transmission interface according to claim 30, wherein the first control messages are time sensitive congestion alarm and recovery messages.

33. The data transmission interface according to claim 32, wherein the controller cancels a congestion alarm message before transmission from the first buffer after receiving a recovery message and cancels a recovery message before transmission from the first buffer after receiving a congestion alarm message.