Processing communication flows in asymmetrically routed networks

• US 20060268932A1
• Filed: 05/15/2006
• Published: 11/30/2006
• Est. Priority Date: 05/23/2005
• Status: Active Grant

• Current Assignee: Juniper Networks Incorporated
• Original Assignee: Juniper Networks Incorporated
• Inventors: Singh, Balraj, Gugle, Nitin
• Granted Patent: US 7,653,075 B2
• Time in Patent Office: Days
• US Class Current: 370/468
• CPC Class Codes: H04L 12/4633 Interconnection of networks using encapsulation techniques, e.g. tunneling
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/125 by balancing the load, e.g. traffic engineering
• CPC Class Codes: H04L 67/563 Data redirection of data network streams
• CPC Class Codes: H04L 69/16 Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP]
• CPC Class Codes: H04L 69/163 In-band adaptation of TCP data exchange; In-band control procedures

Abstract

A network system includes a first device and a second device separated by a network having asymmetric routes in which traffic forwarded in a first direction from the first device to the second device may travel a different route than traffic forwarded in a second direction from the second device to the first device. At least three intermediate processing devices are located between the first device and the second device, wherein at least two of the intermediate processing devices are located along different asymmetric routes. The intermediate processing devices intercept a communication flow between the first device and the second device, and encapsulate the communication flow within network tunnels so that communications associated with the communication flow in the first direction and the second direction are forwarded between a same set of at least two of the intermediate processing devices.

Claims

1. A method comprising:

establishing network tunnels between at least three intermediate processing devices located between a first device and a second device separated by a network having asymmetric routes in which traffic forwarded in a first direction from the first device to the second device travels a different route than traffic forwarded in a second direction from the second device to the first device,

intercepting, with a first of one of the intermediate processing devices, a request for a communication flow between the first device and the second device, wherein the communication flow includes communications from the first device to the second device and return communications from the second device to the first device;

intercepting, with a second one of the intermediate processing devices, a response from the second device that acknowledges the request for the communication flow; and

encapsulating, with the intermediate processing devices, the communications of the communication flow within the network tunnels so that the communications associated with the communication flow are forwarded through the network between the first one of the intermediate processing devices that intercepted the request and the second one of the intermediate processing devices that intercepted the response.

2. The method of claim 1, wherein the request comprises a Transmission Control Protocol (TCP) SYN packet, and the response comprises a TCP SYN ACK packet.

3. The method of claim 1,

wherein the at least three intermediate processing devices includes a first intermediate processing device associated with the first device, and second and third intermediate processing devices associated with the second device, and

wherein establishing network tunnels comprises:

establishing a first tunnel between the first intermediate processing device and the second intermediate processing device; and

establishing a second tunnel between the first intermediate processing device and the third intermediate processing device.

4. The method of claim 3, further comprising:

after intercepting the request with the first intermediate processing device, updating flow data stored within the first intermediate processing device to add the flow being requested, and forwarding the request from the first intermediate processing device in accordance with a local routing table of the first intermediate device.

5. The method of claim 3, further comprising:

when the third intermediate processing device receives the request, forwarding a notification from the third intermediate processing device to the second intermediate processing device to inform the second intermediate processing device of the communication flow being requested.

6. The method of claim 5, wherein the notification includes information specifying the requested flow and information identifying the first intermediate processing device that intercepted the request.

7. The method of claim 5, further comprising:

receiving the notification with the second intermediate processing device;

in response to the notification, determining an identity of the first intermediate processing device that intercepted the request based on the notification;

forwarding the intercepted response from the second intermediate processing device to the first intermediate processing device via the first tunnel; and

updating flow data stored within the second intermediate processing device to add the flow being requested; and

forwarding, as encapsulated packets via the second tunnel, communications of the flow from the second one of the intermediate processing devices to the first one of the intermediate processing devices.

8. The method of claim 7, further comprising:

upon receiving the intercepted response with the first intermediate processing device via the first tunnel, performing the following with the first intermediate processing device;

determining an identity of the second intermediate processing device that intercepted the response;

determining whether the request and response traveled asymmetric routes; and

when the request and response traveled asymmetric routes, updating flow data within the first intermediate processing device and forwarding, as encapsulated packets via the second tunnel, communications of the flow from the first one of the intermediate processing devices to the second one of the intermediate processing devices.

9. The method of claim 3, further comprising:

assigning the first intermediate processing device to a first cluster; and

assigning the second and third intermediate processing devices to a second cluster.

10. The method of claim 3, further comprising:

detecting with the intermediate processing devices advertisement messages that identify destinations serviced by the other intermediate processing devices; and

automatically assigning the intermediate processing devices to the first cluster or the second cluster based on the advertisement messages.

11. A network system comprising:

a first device and a second device separated by a network having asymmetric routes in which traffic forwarded in a first direction from the first device to the second device travels a different route than traffic forwarded in a second direction from the second device to the first device;

at least three intermediate processing devices located between the first device and the second device, wherein at least two of the intermediate processing devices are located along different ones of the asymmetric routes; and

at least two network tunnels established between the intermediate processing devices;

wherein the intermediate processing devices intercept a communication flow between the first device and the second device and encapsulate the communication flow within the network tunnels so that communications associated with the communication flow in the first direction and the second direct are forwarded between a same set of at least two of the intermediate processing devices.

12. The network system of claim 11,

wherein a first of one of the intermediate processing devices includes an I/O module that intercepts a request for the communication flow between the first device and the second device,

wherein a second of one of the intermediate processing devices includes an I/O module that intercepts a response from the second device that acknowledges the request for the communication flow, and

wherein the first one of the intermediate processing devices and the second intermediate processing devices form the set of at least two of the intermediate processing devices between which the communications associated with the communication flow in the first direction and the second direct are forwarded via the tunnels.

13. The network system of claim 11, wherein the tunnels include:

a first tunnel between the first intermediate processing device and the second intermediate processing device, and

a second tunnel between the first intermediate processing device and the third intermediate processing device of the intermediate processing devices.

14. The network system of claim 13,

wherein the first intermediate processing devices comprises a memory that stores flow data, and wherein the first intermediate processing device updates the flow data stored within memory to add the flow being requested.

15. The network system of claim 13, wherein the intermediate processing devices include:

the first intermediate processing device that outputs the intercepted request according to a local routing table;

the third intermediate processing device that receives the request and forwards a notification of the request to the second intermediate processing device; and

the second intermediate processing device that forwards the intercepted response to the first intermediate processing device via the first tunnel in response to the notification.

16. The network system of claim 14, wherein the notification includes information specifying the requested flow and information identifying the first intermediate processing device that intercepted the request.

17. A computer-readable medium comprising instructions for causing a programmable processor to:

intercept a request for a communication flow between a first device and a second device separated by a network having asymmetric routes in which traffic forwarded in a first direction from the first device to the second device travels a different route than traffic forwarded in a second direction from the second device to the first device; and

encapsulate the communication flow within network tunnels between at least three intermediate processing devices located between the first device and the second device so that communications associated with the communication flow in the first direction and the second direct are forwarded between a same set of at least two of the intermediate processing devices.