SYSTEMS AND METHODS OF PROVIDING PROXY-BASED QUALITY OF SERVICE

• US 20080225715A1
• Filed: 03/12/2007
• Published: 09/18/2008
• Est. Priority Date: 03/12/2007
• Status: Active Grant

• Current Assignee: Citrix Systems, Inc. (Cloud Software Group)
• Original Assignee: Citrix Systems, Inc. (Cloud Software Group)
• Inventors: Plamondon, Robert
• Granted Patent: US 7,706,266 B2
• Time in Patent Office: Days
• US Class Current: 370/232
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: H04L 1/0028 Formatting
• CPC Class Codes: H04L 1/1671 the supervisory signal being transmitted together with control information
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/11 Identifying congestion
• CPC Class Codes: H04L 47/12 Avoiding congestion; Recovering from congestion
• CPC Class Codes: H04L 47/193 at the transport layer, e.g. TCP related
• CPC Class Codes: H04L 47/24 Traffic characterised by specific attributes, e.g. priority or QoS
• CPC Class Codes: H04L 47/263 Rate modification at the source after receiving feedback
• CPC Class Codes: H04L 47/27 Evaluation or update of window size, e.g. using information derived from acknowledged [ACK] packets
• CPC Class Codes: Y02D 30/50 in wire-line communication networks, e.g. low power modes or reduced link rate

Abstract

Systems and methods for dynamically controlling bandwidth of connections are described. In some embodiments, a proxy for one or more connections may allocate, distribute, or generate indications of network congestion via one or more connections in order to induce the senders of the connections to reduce their rates of transmission. The proxy may allocate, distribute, or generate these indications in such a way as to provide quality of service to one or more connections, or to ensure that a number of connections transmit within an accepted bandwidth limit. In other embodiments, a sender of a transport layer connection may have a method for determining a response to congestion indications which accounts for a priority of the connection. In these embodiments, a sender may reduce or increase parameters related to transmission rate at different rates according to a priority of the connection.

Claims

1. A method for providing, by an appliance, quality of service levels to transport layer data communications using a transparent proxy to control connection bandwidth, the method comprising:

(a) determining, by an appliance serving as a transparent proxy for a transport layer connection between a sender and a receiver, that the rate of transmission of the sender via the transport layer connection differs from a predetermined rate of transmission;

(b) generating, by the appliance in response to the determination, an acknowledgement packet containing an indication to alter the rate of transmission; and

(c) transmitting, by the appliance to the sender, the generated acknowledgement packet.

2. The method of claim 1, wherein step (b) comprises generating, by the appliance in response to the determination, an acknowledgement packet containing an indication to alter the rate of transmission, wherein the acknowledgement packet is not generated in response to an acknowledgement received from the receiver.

3. The method of claim 1, wherein step (a) comprises determining, by an appliance serving as a transparent proxy for a TCP connection between a sender and a receiver, that the rate of transmission of the sender via the connection differs from a predetermined rate of transmission.

4. The method of claim 1, wherein step (a) comprises determining, by an appliance serving as a transparent proxy for a plurality of transport layer connections between a plurality of senders and receivers, that the rate of transmission of a sender via one of the connections differs from a predetermined rate of transmission.

5. The method of claim 1, wherein step (a) comprises:

(a-a) determining, by an appliance serving as a transparent proxy for a transport layer connection between a sender and a receiver, that at least one of the sender and receiver is connected to the appliance via a wide-area network; and

(a-b) determining, by the appliance, that the rate of transmission of a sender of the transport layer connection differs from a predetermined rate of transmission.

6. The method of claim 1, wherein step (a) comprises determining, by an appliance serving as a transparent proxy for a transport layer connection between a sender and a receiver, that the rate of transmission of the sender via the connection differs from a predetermined rate of transmission, the predetermined rate of transmission corresponding to a quality of service level assigned to the transport layer connection.

7. The method of claim 1, wherein step (a) comprises determining, by an appliance serving as an transparent proxy for a transport layer connection between a sender and a receiver, that the rate of transmission of the sender via the connection exceeds a predetermined rate of transmission.

8. The method of claim 7, wherein step (b) comprises generating, by the appliance in response to the determination, an acknowledgement containing an indication to reduce a window size of the transport layer connection.

9. The method of claim 7, wherein step (b) comprises generating, by the appliance in response to the determination, an acknowledgement containing an indication to reduce a window size of the transport layer connection, wherein the reduced window size differs from a window size advertised by the receiver via the transport layer connection.

10. The method of claim 7, wherein step (b) comprises generating, by the appliance in response to the determination, an acknowledgement containing marked Explicit Congestion Notification bits.

11. The method of claim 7, wherein step (b) comprises generating, by the appliance in response to the determination, an acknowledgement containing an indication that a packet has been lost.

12. The method of claim 1, wherein step (a) comprises determining, by an appliance serving as a transparent proxy for a transport layer connection between a sender and a receiver, that the rate of transmission of the sender via the connection is below a predetermined rate of transmission.

13. The method of claim 12, wherein step (b) comprises generating, by the appliance in response to the determination, an acknowledgement (acknowledgement) containing an indication to increase a window size of the transport layer connection.

14. A computer-implemented system for providing quality of service levels to transport layer data communications using a transparent proxy to control connection bandwidth, the system comprising:

a network appliance which serves as a transparent proxy for a transport layer connection between one or more senders and one or more receivers, the network appliance comprising;

a flow control module which determines the rate of transmission of the sender via the transport layer connection differs from a predetermined rate of transmission; and

generates, in response to the determination, an acknowledgement containing an indication to alter the rate of transmission; and

a packet processing module which transmits to the sender the generated acknowledgement.

15. The system of claim 14, wherein the flow controller generates, in response to the determination, an acknowledgement packet containing an indication to alter the rate of transmission, wherein the acknowledgement is not generated in response to an acknowledgement received from the receiver.

16. The system of claim 14, wherein the transport layer connection comprises a TCP connection.

17. The system of claim 14, wherein the network appliance serves as a transparent proxy for a plurality of transport layer connections between a plurality of senders and receivers.

18. The system of claim 14, wherein the network appliance further comprises a wide-area network (WAN) detector which determines that at least one of the sender and receiver is connected to the appliance via a WAN.

19. The system of claim 14, wherein the flow control module determines that the rate of transmission of the sender via the connection differs from a predetermined rate of transmission, the predetermined rate of transmission corresponding to a quality of service level assigned to the transport layer connection.

20. The system of claim 14, wherein the flow control module determines that the rate of transmission of the sender via the connection exceeds a predetermined rate of transmission.

21. The system of claim 20, wherein the packet processing module generates, in response to the determination, an acknowledgement containing an indication to reduce a window size of the transport layer connection.

22. The system of claim 20, wherein the packet processing module generates, in response to the determination, an acknowledgement containing an indication to reduce a window size of the transport layer connection, wherein the reduced window size differs from a window size advertised by the receiver via the transport layer connection

23. The method of claim 20, wherein the packet processing module generates, in response to the determination, an acknowledgement containing marked ECN bits.

24. The method of claim 20, wherein the packet processing module generates, in response to the determination, an acknowledgement containing an indication that a packet has been lost.

25. The system of claim 14, wherein the flow control module determines that the rate of transmission of the sender via the connection is below a predetermined rate of transmission.

26. The method of claim 25, wherein the packet processing module generates, in response to the determination, an acknowledgement containing an indication to increase a window size of the transport layer connection.

27. A method for providing provide quality of service levels to transport layer data communications using a transparent proxy to control connection bandwidth, the method comprising:

(a) establishing, by an appliance serving as a transparent proxy, a transport layer connection between a sender and a receiver, the connection having a given priority;

(b) assigning, by the appliance to the transport layer connection, a rate of transmission, the rate of transmission corresponding to the given priority;

(c) determining, by the appliance, that the rate of transmission of the sender via the connection differs from the assigned rate of transmission;

(d) generating, by the appliance in response to the determination, an acknowledgement containing an indication to alter the rate of transmission, wherein the acknowledgement is not generated in response to an acknowledgement received from the receiver; and

(e) transmitting, by the appliance to the sender, the generated acknowledgement.

28. The method of claim 27, wherein step (c) comprises determining, by the appliance, that the rate of transmission of the sender via the connection exceeds the assigned rate of transmission.

29. The method of claim 28, wherein step (d) comprises generating, by the appliance in response to the determination, an acknowledgement containing an indication to reduce a window size of the transport layer connection, wherein the acknowledgement is not generated in response to an acknowledgement received from the receiver.

30. The method of claim 28, wherein step (d) comprises generating, by the appliance in response to the determination, an acknowledgement containing marked ECN bits, wherein the acknowledgement is not generated in response to an acknowledgement received from the receiver.

31. The method of claim 28, wherein step (d) comprises generating, by the appliance in response to the determination, an acknowledgement containing an indication that a packet has been lost, wherein the acknowledgement is not generated in response to an acknowledgement received from the receiver.

32. The method of claim 27, wherein step (c) comprises determining, by the appliance, that the rate of transmission of the sender via the connection is below the assigned rate of transmission.

33. The method of claim 32, wherein step (d) comprises generating, by the appliance in response to the determination, an acknowledgement containing an indication to increase a window size of the transport layer connection, wherein the acknowledgement did not originate from an endpoint of the transport layer connection.