Sending instructions from a service manager to forwarding agents on a need to know basis

• US 6,549,516 B1
• Filed: 07/02/1999
• Issued: 04/15/2003
• Est. Priority Date: 07/02/1999
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Albert, Mark, Tiwari, Pranav Kumar, Menditto, Louis F., Howes, Richard A., Tsang, Tzu-Ming, Jordan, James A., Kersey, Edward A., OʼRourke, Chris
• Primary Examiner(s): Rao, Seema S.
• Assistant Examiner(s): Abelson, Ron
• Application Number:
  US09/347,108
• Time in Patent Office: 1,383 Days
• Field of Search: 370/386, 370/229, 370/230, 370/235, 370/236, 370/428, 370/410, 370/400, 370/401, 370/389, 370/432, 709/203, 709/223, 709/105, 709/226
• US Class Current: 370/236
• CPC Class Codes: H04L 67/1001 for accessing one among a plurality of replicated servers
• CPC Class Codes: H04L 67/1023 based on a hash applied to IP addresses or costs
• CPC Class Codes: H04L 67/1038 Load balancing arrangements to avoid a single path through a load balancer
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]

Abstract

A system and method are described for providing instructions for forwarding packets. The method includes broadcasting a general instruction specifying a plurality of flows to a plurality of forwarding agents and receiving at a service manager a first message responsive to the general instruction indicating that a packet for a specific flow has been received by a specific forwarding agent. A specific instruction is generated at the service manager for handling the specific flow and the specific instruction for handling the specific flow is sent to the specific forwarding agent.

Claims

1. A method of providing instructions for forwarding packets comprising:

broadcasting a general instruction specifying a plurality of flows to a plurality of forwarding agents;

receiving at a service manager a first message responsive to the general instruction indicating that a packet for a specific flow has been received by a specific forwarding agent;

generating a specific instruction at the service manager for handling the specific flow; and

sending the specific instruction for handling the specific flow to the specific forwarding agent;

wherein the specific instruction is stored at the forwarding agent until a forwarding agent expiration interval elapses, the specific instruction is stored at the service manager until a service manager expiration interval elapses, and the service manager expiration interval is greater than the forwarding agent expiration interval; and

wherein the service manager expiration interval is reset when the service manager receives a message from the specific forwarding agent indicating that a packet matching the general instruction has been received by the forwarding agent.

2. A method of providing instructions for forwarding packets as recited in claim 1 further including:

deleting the specific instruction from the forwarding agent when the forwarding agent expiration interval elapses;

receiving at a service manager a second message responsive to the general instruction indicating that a packet for a specific flow has been received by a specific forwarding agent;

finding the specific instruction stored at the service manager for handling the specific flow to the specific forwarding agent;

resetting the service manager expiration interval for the specific instruction stored at the service manager; and

resending the specific instruction for handling the specific flow to the specific forwarding agent.

3. A service manger including:

a forwarding agent sending interface configured to broadcast a general instruction specifying a plurality of flows to a plurality of forwarding agents;

a forwarding agent receiving interface configured to receive messages from the forwarding agents responsive to the general instruction indicating that a packet for a specific flow has been received by one of the forwarding agents;

a processor configured to generate a specific instruction at the service manager for handling the specific flow; and

a memory configured to store the specific instructions;

wherein the forwarding agent sending interface is further configured to send the specific instruction for handling the specific flow to the one of the forwarding agents and the processor is configured to delete the specific instructions from the memory after a period of time; and

wherein the processor is configured to reset the period of time when a subsequent message from one of the forwarding agents is received that is responsive to the general instruction and that indicates that a subsequent packet for the specific flow has been received.

4. A service manger as recited in claim 3 wherein the forwarding agent sending interface is further configured to send a time to live along with the specific instruction for handling the specific flow.

5. A service manger as recited in claim 4 wherein the processor is configured to delete the specific instructions from the memory after a period of time.

6. A service manager as recited in claim 5 wherein the period of time is greater than the time to live.

7. A computer program product for providing instructions for forwarding packets, the computer program product being embodied in a computer readable medium and comprising computer instructions for:

broadcasting a general instruction specifying a plurality of flows to a plurality of forwarding agents;

receiving at a service manager a first message responsive to the general instruction indicating that a packet for a specific flow has been received by a specific forwarding agent;

generating a specific instruction at the service manager for handling the specific flow; and

sending the specific instruction for handling the specific flow to the specific forwarding agent;

wherein the specific instruction is stored at the forwarding agent until a forwarding agent expiration interval elapses, the specific instruction is stored at the service manager until a service manager expiration interval elapses, and the service manager expiration interval is greater than the forwarding agent expiration interval; and

wherein the service manager expiration interval is reset when the service manager receives a message from the specific forwarding agent indicating that a packet matching the general instruction has been received by the forwarding agent.

8. A computer program product for providing instructions for forwarding packet as recited in claim 7, the computer program product further comprising computer instructions for:

deleting the specific instruction from the forwarding agent when the forwarding agent expiration interval elapses;

receiving at a service manager a second message responsive to the general instruction indicating that a packet for a specific flow has been received by a specific forwarding agent;

finding the specific instruction stored at the service manager for handling the specific flow to the specific forwarding agent;

resetting the service manager expiration interval for the specific instruction stored at the service manager; and

resending the specific instruction for handling the specific flow to the specific forwarding agent.