Systems and methods for providing quality of service precedence in TCP congestion control

• US 8,462,631 B2
• Filed: 05/21/2010
• Issued: 06/11/2013
• 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
• Primary Examiner(s): Nguyen, Hanh N
• Application Number:
  US12/784,872
• Publication Number:
  US 20100226250A1
• Time in Patent Office: 1,117 Days
• Field of Search: 370/352, 370/235, 370/395.21, 370/395.4, 370/252, 370/254, 370/232, 370/400, 370/233, 370/234, 370/236, 370/469
• US Class Current: 370/235
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/193 at the transport layer, e.g. TCP related
• CPC Class Codes: H04L 47/27 Evaluation or update of window size, e.g. using information derived from acknowledged [ACK] packets

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 dynamically controlling connection bandwidth by a sender of one or more transport layer connections according to a priority assigned to one or more of the transport layer connections, the method comprising:

transmitting, by a sender executing on a device, data to a receiver via a first transport layer connection, the first transport layer connection having a first congestion window size;

identifying, by the sender, a window size alteration factor corresponding to a priority assigned to the first transport layer connection;

adjusting, by the sender, the first congestion window size by the window size alteration factor to identify a second congestion window size; and

transmitting, by the sender, data via a second transport layer connection, wherein the second transport layer connection has a third congestion window size;

identifying, by the sender, a second window size alteration factor corresponding to a second priority assigned to the second transport layer connection; and

determining a fourth congestion window size, the fourth congestion window size comprising the third congestion window size adjusted by the second window size alteration factor.

2. The method of claim 1, further comprising receiving an indication of a packet loss via the first transport layer connection, and wherein the window size alteration factor is a reduction factor.

3. The method of claim 2, wherein determining the second congestion window size comprises dividing the first congestion window size by the reduction factor.

4. The method of claim 1, further comprising receiving no indications of packet loss events via the first transport layer connection during a time interval, and wherein the window size alteration factor is an enlargement factor.

5. The method of claim 4, wherein determining the second congestion window size comprises multiplying the first congestion window size by the enlargement factor.

6. The method of claim 1, further comprising:

establishing a predetermined rate of transmission for the first transport layer connection; and

identifying the window size alteration factor, responsive to determining that an actual rate of transmission of the sender via the first transport layer connection differs from the predetermined rate of transmission for the first transport layer connection.

7. The method of claim 1, further comprising assigning the priority to the first transport layer connection responsive to at least one of:

past bandwidth consumption, protocol, source address, destination address, and connection burstiness.

8. The method of claim 1, further comprising transmitting, by the sender via the first transport layer connection, data according to the second congestion window size.

9. The method of claim 1, wherein the priority assigned to the first transport layer connection is higher than the second priority assigned to the second transport layer connection, and wherein the window size alteration factor of the first transport layer connection is larger than the second window size alteration factor of the second transport layer connection.

10. A system for dynamically controlling connection bandwidth according to a priority assigned to one or more transport layer connections, the system comprising:

a device deployed as an intermediary receiving and forwarding network traffic between a sender and a receiver via a first transport layer connection, the first transport layer connection having a first congestion window size, and transmits data via a second transport layer connection, the second transport layer connection having a second congestion window size; and

a flow control module of the device;

identifying a window size alteration factor corresponding to a priority assigned by the device to the first transport layer connection,

determining a third congestion window size for the first transport layer connection, the third congestion window size comprising the first congestion window size adjusted by the window size alteration factor,

determining a second window size alteration factor corresponding to a second priority assigned to the second transport layer connection, and

determining a fourth congestion window size, the fourth congestion window size comprising the second congestion window size adjusted by the second window size alteration factor.

11. The system of claim 10, wherein the device receives an indication of a packet loss via the first transport layer connection, and wherein the window size alteration factor is a reduction factor.

12. The system of claim 11, wherein the flow control module computes the third congestion window size by dividing the first congestion window size by the reduction factor.

13. The system of claim 10, wherein the device receives no indications of packet loss events via the first transport layer connection during a time interval, and wherein the window size alteration factor is an enlargement factor.

14. The system of claim 13, wherein the flow control module computes the third congestion window size by multiplying the first congestion window size by the enlargement factor.

15. The system of claim 10, wherein the flow control module further establishes a predetermined rate of transmission for the first transport layer connection;

and computes the window size alteration factor, responsive to determining that an actual rate of transmission of the sender via the first transport layer connection differs from the predetermined rate of transmission for the first transport layer connection.

16. The system of claim 10, wherein the flow control module assigns the priority to the first transport layer connection responsive to at least one of:

past bandwidth consumption, protocol, source address, destination address, and connection burstiness.

17. The system of claim 10, wherein the device further transmits, via the first transport layer connection, data according to the third congestion window size.

18. The system of claim 10, wherein the priority assigned to the first transport layer connection is higher than the second priority assigned to the second transport layer connection, and wherein the window size alteration factor of the first transport layer connection is larger than the second window size alteration factor of the second transport layer connection.