Reducing Buffer Usage for TCP Proxy Session Based on Delayed Acknowledgement

• US 20140207845A1
• Filed: 01/23/2013
• Published: 07/24/2014
• Est. Priority Date: 01/23/2013
• Status: Active Grant

• Current Assignee: A10 Networks Incorporated
• Original Assignee: A10 Networks Incorporated
• Inventors: Han, Liang, Cao, Zhiruo
• Granted Patent: US 9,531,846 B2
• Time in Patent Office: Days
• US Class Current: 709/203
• CPC Class Codes: G06F 8/355 Round-trip engineering
• CPC Class Codes: H04L 43/0864 Round trip delays
• CPC Class Codes: H04L 43/16 Threshold monitoring
• CPC Class Codes: H04L 47/283 in response to processing delays, e.g. caused by jitter or round trip time [RTT]
• CPC Class Codes: H04L 67/01 Protocols
• CPC Class Codes: H04L 69/16 Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP]

Abstract

Reducing buffer usage for a TCP proxy session between a client and a server by a service gateway includes: determining a first round trip time (RTT) for a server side TCP session and determining a second RTT for a client side TCP session; comparing the first RTT with the second RTT; determining whether the second RTT exceeds the first RTT beyond a threshold; if so, then calculating a desired RTT based on the second RTT; and setting a timer according to the calculated desired RTT, where a TCP acknowledgment for the server side TCP session is delayed until the timer expires. The desired RTT may be calculated as a percentage of the second RTT or as the second RTT minus a predetermined value. The service gateway waits until the timer has expired before sending a TCP acknowledgment data packet to the server.

Claims

1. A method for reducing buffer usage for a Transmission Control Protocol (TCP) proxy session between a client and a server, comprising:

(a) determining a first round trip time (RTT) for a server side TCP session of the TCP proxy session between a service gateway and the server, and determining a second RTT for a client side TCP session of the TCP proxy session between the service gateway and the client;

(b) comparing the first RTT with the second RTT by the service gateway;

(c) determining whether the second RTT exceeds the first RTT;

(d) in response to determining that the second RTT exceeds the first RTT, calculating by the service gateway a desired RTT based on the second RTT; and

(e) setting a timer by the service gateway according to the calculated desired RTT, wherein a TCP acknowledgment for the server side TCP session is delayed until the timer expires.

2. The method of claim 1, wherein the determining (c) and the calculating (d) comprise:

(c1) determining whether the second RTT exceeds the first RTT beyond a predetermined threshold; and

(d1) in response to determining that the second RTT exceeds the first RTT beyond the predetermined threshold, calculating by the service gateway the desired RTT based on the second RTT.

3. The method of claim 1, wherein the calculating (d) comprises:

(d1) calculating by the service gateway the desired RTT as a percentage of the second RTT.

4. The method of claim 1, wherein the calculating (d) comprises:

(d1) calculating by the service gateway the desired RTT as the second RTT minus a predetermined value.

5. The method of claim 1, wherein the setting (e) comprises:

(e1) receiving by the service gateway a data packet from the server over the server side TCP session;

(e2) determining by the service gateway a need to send the TCP acknowledgment to the server;

(e3) setting a timer to the desired RTT by the service gateway; and

(e4) in response to an expiration of the timer, sending the TCP acknowledgment to the server by the service gateway.

6. A non-transitory computer readable medium with computer readable program code embodied therewith for reducing buffer usage for a Transmission Control Protocol (TCP) proxy session between a client and a server, the computer readable program code configured to:

(a) determine a first round trip time (RTT) for a server side TCP session of the TCP proxy session between a service gateway and the server, and determining a second RTT for a client side TCP session of the TCP proxy session between the service gateway and the client;

(b) compare the first RTT with the second RTT;

(c) determine whether the second RTT exceeds the first RTT;

(d) in response to determining that the second RTT exceeds the first RTT, calculate a desired RTT based on the second RTT; and

(e) set a timer according to the calculated desired RTT, wherein a TCP acknowledgment for the server side TCP session is delayed until the timer expires.

7. The medium of claim 6, wherein the computer readable program code configured to determine (c) and to calculate (d) are further configured to:

(c1) determine whether the second RTT exceeds the first RTT beyond a predetermined threshold; and

(d1) in response to determining that the second RTT exceeds the first RTT beyond the predetermined threshold, calculating by the service gateway the desired RTT based on the second RTT.

8. The medium of claim 6, wherein the computer readable program code configured to calculate (d) is further configured to:

(d1) calculate the desired RTT as a percentage of the second RTT.

9. The medium of claim 6, wherein the computer readable program code configured to calculate (d) is further configured to:

(d1) calculate the desired RTT as the second RTT minus a predetermined value.

10. The medium of claim 6, where computer readable program code configured to set (e) is further configured to:

(e1) receive a data packet from the server over the server side TCP session;

(e2) determine a need to send the TCP acknowledgment to the server;

(e3) set a timer to the desired RTT; and

e4) in response to an expiration of the timer, send the TCP acknowledgment to the server.

11. A system for reducing buffer usage for a Transmission Control Protocol (TCP) proxy session between a client and a server, comprising:

a security gateway, wherein a server side TCP session of the TCP proxy session is established between the security gateway and the server, wherein a client side TCP session of the TCP proxy session is established between the security gateway and the client, wherein the security gateway;

(a) determines a first round trip time (RTT) for a server side TCP session of the TCP proxy session between a service gateway and the server, and determining a second RTT for a client side TCP session of the TCP proxy session between the service gateway and the client;

(b) compares the first RTT with the second RTT;

(c) determines whether the second RTT exceeds the first RTT;

(d) in response to determining that the second RTT exceeds the first RTT, calculates a desired RTT based on the second RTT; and

(e) sets a timer according to the calculated desired RTT, wherein a TCP acknowledgment for the server side TCP session is delayed until the timer expires.

12. The system of claim 11, wherein the determines (c) and the calculates (d) comprise:

(c1) determines whether the second RTT exceeds the first RTT beyond a predetermined threshold; and

(d1) in response to determining that the second RTT exceeds the first RTT beyond the predetermined threshold, calculates the desired RTT based on the second RTT.

13. The system of claim 11, wherein the calculates (d) comprises:

(d1) calculates the desired RTT as a percentage of the second RTT.

14. The system of claim 11, wherein the calculates (d) comprises:

(d1) calculates the desired RTT as the second RTT minus a predetermined value.

15. The system of claim 11, wherein the sets (e) further comprises:

(e1) receives a data packet from the server over the server side TCP session;

(e2) determines a need to send the TCP acknowledgment to the server;

(e3) sets a timer to the desired RTT; and

(e4) in response to an expiration of the timer, sends the TCP acknowledgment to the server.