System and Method for Synchronizing Packet Forwarding Information

• US 20090052445A1
• Filed: 08/24/2007
• Published: 02/26/2009
• Est. Priority Date: 08/24/2007
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Network Communications Incorporated (Fujitsu Limited)
• Inventors: Folkes, Ronald P.
• Granted Patent: US 7,903,665 B2
• Time in Patent Office: Days
• US Class Current: 370/389
• CPC Class Codes: H04L 45/02 Topology update or discovery
• CPC Class Codes: H04L 45/021 Ensuring consistency of routing table updates, e.g. by using epoch numbers
• CPC Class Codes: H04L 45/54 Organization of routing tables
• CPC Class Codes: H04L 45/64 using an overlay routing layer

Abstract

In accordance with the teachings of the present invention, a system and method for synchronizing packet forwarding information is provided. In a particular embodiment, the system includes a control processor configured to implement a control plane to generate first forwarding information and transfer the first forwarding information to an active forwarding table of a network processor. The system also includes a network processor configured to implement a forwarding plane to receive packets and use the first forwarding information in the active forwarding table to forward the received packets to one or more network devices. After the control plane is restarted, the control processor is further configured to use the restarted control plane to generate second forwarding information and incrementally update the first forwarding information in the active forwarding table with the second forwarding information while the network processor'"'"'s forwarding plane continues to forward traffic.

Claims

1. A system for synchronizing packet forwarding information, comprising:

a control processor configured to implement a control plane to generate first forwarding information and transfer the first forwarding information to an active forwarding table of a network processor; and

a network processor configured to implement a forwarding plane to receive packets and use the first forwarding information in the active forwarding table to forward the received packets to one or more network devices;

wherein, after the control plane is restarted, the control processor is further configured to use the restarted control plane to generate second forwarding information and incrementally update the first forwarding information in the active forwarding table with the second forwarding information while the network processor'"'"'s forwarding plane continues to forward traffic.

2. The system of claim 1, wherein the restarted control plane incrementally updates the first forwarding information in the active forwarding table with the second forwarding information by incrementally adding to the active forwarding table forwarding information comprised in the second forwarding information that is not already comprised in the active forwarding table.

3. The system of claim 1, wherein the restarted control plane incrementally updates the first forwarding information in the active forwarding table with the second forwarding information by incrementally removing from the active forwarding table forwarding information that is not comprised in the second forwarding information.

4. The system of claim 1, wherein the restarted control plane is further configured to:

read the first forwarding information in the active forwarding table to create an internal copy of the first forwarding information; and

compare the second forwarding information to the internal copy of the first forwarding information to incrementally update the first forwarding information in the active forwarding table with the second forwarding information.

5. The system of claim 1, wherein the network processor'"'"'s forwarding plane continues to forward traffic based on the incrementally updated forwarding information in the active forwarding table.

6. A method for synchronizing packet forwarding information, comprising:

using a control plane, generating first forwarding information and transferring the first forwarding information to an active forwarding table;

using a forwarding plane, receiving packets and using the first forwarding information in the active forwarding table to forward the received packets to one or more network devices; and

after the control plane is restarted, generating second forwarding information and incrementally updating the first forwarding information in the active forwarding table with the second forwarding information using the restarted control plane while continuing to forward traffic using the forwarding plane.

7. The method of claim 6, wherein the restarted control plane incrementally updates the first forwarding information in the active forwarding table with the second forwarding information by incrementally adding to the active forwarding table forwarding information comprised in the second forwarding information that is not already comprised in the active forwarding table.

8. The method of claim 6, wherein the restarted control plane incrementally updates the first forwarding information in the active forwarding table with the second forwarding information by incrementally removing from the active forwarding table forwarding information that is not comprised in the second forwarding information.

9. The method of claim 6, further comprising, using the restarted control plane:

reading the first forwarding information in the active forwarding table to create an internal copy of the first forwarding information; and

comparing the second forwarding information to the internal copy of the first forwarding information to incrementally update the first forwarding information in the active forwarding table with the second forwarding information.

10. The method of claim 6, wherein traffic continues to be forwarded using the forwarding plane based on the incrementally updated forwarding information in the active forwarding table.

11. Logic encoded on a computer-readable medium and comprising control logic and forwarding logic, wherein:

the control logic is operable, when executed by a computer, to generate first forwarding information and transfer the first forwarding information to an active forwarding table;

the forwarding logic is operable, when executed by a computer, to receive packets and use the first forwarding information in the active forwarding table to forward the received packets to one or more network devices; and

after the control logic is restarted, the restarted control logic is further operable to generate second forwarding information and incrementally update the first forwarding information in the active forwarding table with the second forwarding information while the forwarding logic continues to forward traffic.

12. The logic of claim 11, wherein the restarted control logic incrementally updates the first forwarding information in the active forwarding table with the second forwarding information by incrementally adding to the active forwarding table forwarding information comprised in the second forwarding information that is not already comprised in the active forwarding table.

13. The logic of claim 11, wherein the restarted control logic incrementally updates the first forwarding information in the active forwarding table with the second forwarding information by incrementally removing from the active forwarding table forwarding information that is not comprised in the second forwarding information.

14. The logic of claim 11, wherein the restarted logic is further operable when executed to:

read the first forwarding information in the active forwarding table to create an internal copy of the first forwarding information; and

compare the second forwarding information to the internal copy of the first forwarding information to incrementally update the first forwarding information in the active forwarding table with the second forwarding information.

15. The logic of claim 11, wherein the forwarding logic continues to forward traffic based on the incrementally updated forwarding information in the active forwarding table.