Overload reduction in a communication system

• US 6,707,792 B1
• Filed: 06/30/1998
• Issued: 03/16/2004
• Est. Priority Date: 06/30/1998
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Volftsun, Lev, Neighbors, Clay H., Rednor, Fred R.
• Primary Examiner(s): Nguyen, Steven H. D
• Assistant Examiner(s): PHAN, MAN U
• Application Number:
  US09/107,839
• Time in Patent Office: 2,086 Days
• Field of Search: 370/235, 370/236, 370/230, 370/395, 370/410, 370/522, 370/545, 370/412, 370/351, 379/219, 379/220, 379/230, 379/279, 379/337, 709/103, 709/106, 709/207, 709/224, 709/310
• US Class Current: 370/235
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/12 Avoiding congestion; Recovering from congestion
• CPC Class Codes: H04L 47/30 in combination with information about buffer occupancy at either end or at transit nodes
• CPC Class Codes: H04L 47/32 by discarding or delaying data units, e.g. packets or frames
• CPC Class Codes: H04M 3/36 Statistical metering, e.g. recording occasions when traffic exceeds capacity of trunks
• CPC Class Codes: H04M 3/367 Traffic or load control
• CPC Class Codes: H04Q 2213/13166 Fault prevention
• CPC Class Codes: H04Q 2213/13344 Overflow

Abstract

A method and apparatus for reducing overload conditions of a node of communication system is disclosed. One or more pairs of predefined upper and lower overload threshold values are stored. A rejection proportion value is stored in association with each of the pairs of overload threshold values. Messages arrive at the node and are processed by it. The current processing load or saturation level of the node is continuously measured in real time. The current saturation level is associated with one of the predefined pairs of overload threshold values. The node rejects a number of messages equal to the rejection proportion value that is associated with the overload threshold values that correspond to the current saturation level. Preferably, only call initialization messages, such as call setup messages or initial address messages, are rejected. Accordingly, the node rejects those messages which, if acknowledged, would lead to the creation and transmission of numerous other messages and would worsen the overload condition. The node may be a call processor in a telecommunication network, such as a universal protocol converter.

Claims

1. A method for reducing an overload condition at a node of a communication system, comprising the steps of:

storing a plurality of upper and lower overload level values in a memory, wherein each upper and lower overload level value corresponds to a saturation condition of the node, and wherein the storing includes

storing an upper overload level threshold value and a lower overload level threshold value in association with each of the plurality of overload level values, in which the upper overload level threshold value of a lesser overload level value slightly overlaps the lower overload level threshold value of a higher overload level value, whereby such overlap dampens behavior of the method;

storing a plurality of rejection proportion values in the memory, wherein each rejection proportion value is associated with one of the overload level values;

determining the current saturation level of the node; and

rejecting a quantity of messages received at the node equal to the rejection proportion value associated with one of the upper and lower overload level values that corresponds to the current saturation level.

2. A method for reducing an overload condition at a node of a communication system, comprising the steps of:

storing a plurality of upper and lower overload level values in a memory, wherein each upper and lower overload level value corresponds to a saturation condition of the node;

storing a plurality of rejection proportion values in the memory, wherein each rejection proportion value is associated with one of the overload level values;

determining the current saturation level of the node;

rejecting a quantity of messages received at the node equal to the rejection proportion value associated with one of the upper and lower overload level values that corresponds to the current saturation level, including rejecting every nth call initialization message received at the node, in which n is a rejection value associated with an overload level value that is exceeded;

wherein the node is a call processor and the messages received at the node are call initialization messages that represent requests to the call processor to process a new call;

receiving the message at an interface having a message queue;

determining a current saturation level of the message queue; and

storing the message in the message queue when the message is not rejected;

storing a rejection threshold value m in the memory in association with a loading level of a processor of the call processor;

receiving one or more messages from the message queue at the processor; and

rejecting every mth message received at the processor when the loading level of the processor exceeds a predetermined maximum loading level.

3. The method recited in claim 2, in which the step of rejecting comprises the step of:

rejecting every mth call initialization message received at the processor when the loading level of the processor exceeds the predetermined maximum loading level.

4. A method for reducing overloading of a call processor in a telecommunications network, comprising the steps of:

storing a plurality of pairs of upper and lower overload level values in a memory of the call processor, wherein each pair of upper and lower overload level values corresponds to a saturation condition of the call processor, including

storing a plurality of message queue values that each represent an amount of occupied storage within a message queue;

storing a plurality of rejection proportion values in the memory, wherein each rejection proportion value is associated with one of the pairs of overload level values;

receiving call initialization messages at a message queue of an interface of the call processor

determining when a current saturation level of the call processor exceeds one of the plurality of overload values, including

determining when a current storage level of the message queue exceeds one of the message queue values; and

rejecting a proportion of the call initialization messages received at the call processor equal to the rejection proportion values associated with that pair of overload level values that corresponds to the current saturation level, and in which each call initialization message is a request to the call processor to process a new call for the telecommunications system.

5. A method for reducing overloading of a call processor in a telecommunications network, comprising the steps of:

storing a plurality of pairs of upper and lower overload level values in a memory of the call processor, wherein each pair of upper and lower overload level values corresponds to a saturation condition of the call processor, including

storing a plurality of processor load values that each represent an amount of processor usage loading;

storing a plurality of rejection proportion values in the memory, wherein each rejection proportion value is associated with one of the pairs of overload level values;

receiving call initialization messages at a central processor of an interface of the call processor

determining when a current saturation level of the call processor exceeds one of the plurality of overload values, including

determining when a current processor load of the central processor exceeds one of the processor load values; and

rejecting a proportion of the call initialization messages received at the call processor equal to the rejection proportion values associated with that pair of overload level values that corresponds to the current saturation level, and in which each call initialization message is a request to the call processor to process a new call for the telecommunications system.

6. A computer readable medium carrying one or more sequences of instructions for reducing an overload condition at a node of a communication system, wherein execution of the one or more sequences of instructions by one or more processors causes the one or more processors to perform the steps of:

storing a plurality of upper and lower overload level values in a memory, wherein each upper and lower overload level value corresponds to a saturation condition of the node;

storing a plurality of rejection proportion values in the memory, wherein each rejection proportion value is associated with one of the overload level values;

determining the current saturation level of the node;

rejecting a quantity of messages received at the node equal to the rejection proportion value associated with one of the upper and lower overload level values that corresponds to the current saturation level;

identifying a message type of the message received at the node;

determining whether the message type is a first type that can be rejected or a second type that cannot be rejected; and

rejecting only messages of the first type.

7. A computer readable medium carrying one or more sequences of instructions for reducing an overload condition at a node of a communication system, wherein execution of the one or more sequences of instructions by one or more processors causes the one or more processors to perform the steps of:

storing a plurality of upper and lower overload level values in a memory, wherein each upper and lower overload level value corresponds to a saturation condition of the node;

storing a plurality of rejection proportion values in the memory, wherein each rejection proportion value is associated with one of the overload level values;

determining the current saturation level of the node;

rejecting a quantity of call initialization messages received at the node equal to the rejection proportion value associated with one of the upper and lower overload level values that corresponds to the current saturation level, including

rejecting every nth call initialization message received at the node, in which n is a rejection value associated with an overload level value that is exceeded.

8. The method of claim 7, wherein the node is a universal protocol converter.

9. A computer-readable medium carrying one or more sequences of instructions for reducing an overload condition at a node of a communication system, wherein execution of the one or more sequences of instructions by one or more processors causes the one or more processors to perform the steps of:

storing a plurality of upper and lower overload level values in a memory, wherein each upper and lower overload level value corresponds to a saturation condition of the node, and wherein the storing includes

storing an upper overload level threshold value and a lower overload level threshold value in association with each of the plurality of overload level values, in which the upper overload level threshold value of a lesser overload level value slightly overlaps the lower overload level threshold value of a higher overload level value, whereby such overlap dampens behavior of reducing the overload condition;

storing a plurality of rejection proportion values in the memory, wherein each rejection proportion value is associated with one of the overload level values;

determining a current saturation level of the node; and

rejecting a quantity of messages received at the node equal to a rejection proportion value associated with one of the upper and lower overload level values that corresponds to the current saturation level.

10. A computer-readable medium carrying one or more sequences of instructions for reducing an overload condition at a node of a communication system, wherein execution of the one or more sequences of instructions by one or more processors causes the one or more processors to perform the steps of:

storing a plurality of upper and lower overload level values in a memory, wherein each upper and lower overload level value corresponds to a saturation condition of the node;

storing a plurality of rejection proportion values in the memory, wherein each rejection proportion value is associated with one of the overload level values;

determining a current saturation level of the node;

rejecting a quantity of messages received at the node equal to a rejection proportion value associated with one of the upper and lower overload level values that corresponds to the current saturation level, including rejecting every nth call initialization message received at the node, in which n is a rejection value associated with an overload level value that is exceeded;

wherein the node is a call processor and the messages received at the node are call initialization messages that represent requests to the call processor to process a new call;

receiving a message at an interface having a message queue;

determining a current saturation level of the message queue; and

storing the message in the message queue when the message is not rejected;

storing a rejection threshold value m in the memory in association with a loading level of a processor of the call processor;

receiving one or more messages from the message queue at the processor; and

rejecting every mth message received at the processor when the loading level of the processor exceeds a predetermined maximum loading level.

11. The computer-readable medium recited in claim 10, in which the step of rejecting comprises the step of:

rejecting every mth call initialization message received at the processor when the loading level of the processor exceeds the predetermined maximum loading level.

12. A computer-readable medium carrying one or more sequences of instructions for reducing overloading of a call processor in a telecommunications network, wherein execution of the one or more sequences of instructions by one or more processors causes the one or more processors to perform the steps of:

storing a plurality of pairs of upper and lower overload level values in a memory of the call processor, wherein each pair of upper and lower overload level values corresponds to a saturation condition of the call processor, including

storing a plurality of message queue values that each represent an amount of occupied storage within a message queue;

storing a plurality of rejection proportion values in the memory, wherein each rejection proportion value is associated with one of the pairs of overload level values;

receiving call initialization messages at a message queue of an interface of the call processor;

determining when a current saturation level of the call processor exceeds one of the plurality of overload level values, including

determining when a current storage level of the message queue of the interface of the call processor exceeds one of the message queue values; and

rejecting a proportion of the call initialization messages received at the call processor equal to a rejection proportion value associated with that pair of overload level values that corresponds to the current saturation level, and in which each call initialization message is a request to the call processor to process a new call for the telecommunications network.

13. A computer-readable medium carrying one or more sequences of instructions for reducing overloading of a call processor in a telecommunications network, wherein execution of the one or more sequences of instructions by one or more processors causes the one or more processors to perform the steps of:

storing a plurality of pairs of upper and lower overload level values in a memory of the call processor, wherein each pair of upper and lower overload level values corresponds to a saturation condition of the call processor, including

storing a plurality of processor load values that each represent an amount of processor usage loading;

storing a plurality of rejection proportion values in the memory, wherein each rejection proportion value is associated with one of the pairs of overload level values;

receiving call initialization messages at a central processor of an interface of the call processor;

determining when a current saturation level of the call processor exceeds one of the plurality of overload levels values, including

determining when a current processor load of the central processor exceeds one of the processor load values; and

rejecting a proportion of the call initialization messages received at the call processor equal to a rejection proportion values associated with that pair of overload level values that corresponds to the current saturation level, and in which each call initialization message is a request to the call processor to process a new call for the telecommunications network.

14. A system for reducing an overload condition at a node of a communication system, the system comprising:

means for storing a plurality of upper and lower overload level values in a memory, wherein each upper and lower overload level value corresponds to a saturation condition of the node, and wherein the means for storing includes

means for storing an upper overload level threshold value and a lower overload level threshold value in association with each of the plurality of overload level values, in which the upper overload level threshold value of a lesser overload level value slightly overlaps the lower overload level threshold value of a higher overload level value, whereby such overlap dampens behavior of the system;

means for storing a plurality of rejection proportion values in the memory, wherein each rejection proportion value is associated with one of the overload level values;

means for determining a current saturation level of the node; and

means for rejecting a quantity of messages received at the node equal to a rejection proportion value associated with one of the upper and lower overload level values that corresponds to the current saturation level.

15. A system for reducing an overload condition at a node of a communication system, the system comprising:

means for storing a plurality of upper and lower overload level values in a memory, wherein each upper and lower overload level value corresponds to a saturation condition of the node;

means for storing a plurality of rejection proportion values in the memory, wherein each rejection proportion value is associated with one of the overload level values;

means for determining a current saturation level of the node;

means for rejecting a quantity of messages received at the node equal to a rejection proportion value associated with one of the upper and lower overload level values that corresponds to the current saturation level, including

means for rejecting every nth call initialization message received at the node, in which n is a rejection value associated with an overload level value that is exceeded;

wherein the node is a call processor and the messages received at the node are call initialization messages that represent requests to the call processor to process a new call;

means for receiving a message at an interface having a message queue;

means for determining a current saturation level of the message queue; and

means for storing the message in the message queue when the message is not rejected;

means for storing a rejection threshold value m in the memory in association with a loading level of a processor of the call processor;

means for receiving one or more messages from the message queue at the processor; and

means for rejecting every mth message received at the processor when the loading level of the processor exceeds a predetermined maximum loading level.

16. A system for reducing overloading of a call processor in a telecommunications network, the system comprising:

means for storing a plurality of pairs of upper and lower overload level values in a memory of the call processor, wherein each pair of upper and lower overload level values corresponds to a saturation condition of the call processor, including

means for storing a plurality of message queue values that each represent an amount of occupied storage within a message queue;

means for storing a plurality of rejection proportion values in the memory, wherein each rejection proportion value is associated with one of the pairs of overload level values;

means for receiving a call initialization messages at a message queue of an interface of the call processor;

means for determining when a current saturation level of the call processor exceeds one of the plurality of overload values, including

means for determining when a current storage level of the message queue of the interface of the call processor exceeds one of the message queue values; and

means for rejecting a proportion of the call initialization messages received at the call processor equal to a rejection proportion value associated with that pair of overload level values that corresponds to the current saturation level, and in which each call initialization message is a request to the call processor to process a new call for the telecommunications network.

17. A system for reducing overloading of a call processor in a telecommunications network, the system comprising:

means for storing a plurality of pairs of upper and lower overload level values in a memory of the call processor, wherein each pair of upper and lower overload level values corresponds to a saturation condition of the call processor, including

means for storing a plurality of processor load values that each represent an amount of processor usage loading;

means for storing a plurality of rejection proportion values in the memory, wherein each rejection proportion value is associated with one of the pairs of overload level values;

means for receiving call initialization messages at a central processor of an interface of the call processor;

means for determining when a current saturation level of the call processor exceeds one of the plurality of overload values, including

means for determining when a current processor load of the central processor exceeds one of the processor load values; and

means for rejecting a proportion of the call initialization messages received at the call processor equal to a rejection proportion value associated with that pair of overload level values that corresponds to the current saturation level, and in which each call initialization message is a request to the call processor to process a new call for the telecommunications network.

18. A system for reducing an overload condition at a node of a communication system, the system comprising:

means for storing a plurality of upper and lower overload level values in a memory, wherein each upper and lower overload level value corresponds to a saturation condition of the node;

means for storing a plurality of rejection proportion values in the memory, wherein each rejection proportion value is associated with one of the overload level values;

means for determining the current saturation level of the node;

means for rejecting a quantity of messages received at the node equal to a rejection proportion value associated with one of the upper and lower overload level values that corresponds to the current saturation level;

means for identifying a message type of a message received at the node;

means for determining whether the message type is a first type that can be rejected or a second type that cannot be rejected; and

means for rejecting only messages of the first type.

19. A system for reducing an overload condition at a node of a communication system, the system comprising:

means for storing a plurality of upper and lower overload level values in a memory, wherein each upper and lower overload level value corresponds to a saturation condition of the node;

means for storing a plurality of rejection proportion values in the memory, wherein each rejection proportion value is associated with one of the overload level values;

means for determining a current saturation level of the node;

means for rejecting a quantity of call initialization messages received at the node equal to a rejection proportion value associated with one of the upper and lower overload level values that corresponds to the current saturation level, including

means for rejecting every nth call initialization message received at the node, in which n is a rejection value associated with an overload level value that is exceeded.