Reducing buffer usage for TCP proxy session based on delayed acknowledgement

Patent metadata

Field	Value
Publication number	US-9979665-B2
Application number	US-201615374935-A
Country	US
Kind code	B2
Filing date	Dec 9, 2016
Priority date	Jan 23, 2013
Publication date	May 22, 2018
Grant date	May 22, 2018

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 acknowledgement 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 acknowledgement data packet to the server.

First claim

What is claimed is:

1. A method for reducing memory usage of a service gateway buffer resident in a memory module of a service gateway for a Transmission Control Protocol (TCP) proxy session between a client and a server by adjusting server side session transmission time to reduce buffer usage, comprising:
determining a first round trip time (RTT) for a server side TCP session of the TCP proxy session between the service gateway and the server, the first RTT being estimated based at least on an average of one or more prior server side TCP sessions with the server;
determining a second RTT for the client side TCP session of the TCP proxy session between the service gateway and the client, the second RTT being estimated based at least on an average of one or more prior client side TCP sessions with the client;
comparing the first RTT with the second RTT by the service gateway;
determining that the second RTT exceeds the first RTT;
comparing a difference between the second RTT and the first RTT;
in response to determining that the difference is above a predetermined threshold, calculating by the service gateway a desired RTT based on the second RTT, the calculation based at least in part on a memory capacity of server side receive buffer; and
setting a timer by the service gateway according to the calculated desired RTT, wherein a TCP acknowledgement for the server side TCP session is delayed until the service gateway determines that the timer expires.

2. The method of claim 1 , wherein the determining whether the second RTT exceeds the first RTT and the calculating a desired RTT based on the second RTT comprise:
determining whether the second RTT exceeds the first RTT beyond a predetermined threshold; and
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 a desired RTT based on the second RTT comprises:
calculating by the service gateway the desired RTT as a percentage of the second RTT.

4. The method of claim 1 , wherein the calculating a desired RTT based on the second RTT comprises: 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 a timer by the service gateway according to the calculated desired RTT comprises:
receiving by the service gateway a data packet from the server over the server side TCP session;
determining by the service gateway a need to send the TCP acknowledgement to the server;
setting a timer to the desired RTT by the service gateway; and
in response to an expiration of the timer, sending the TCP acknowledgement to the server by the service gateway.

6. The method of claim 1 , wherein the second RTT is determined at periodic intervals.

7. The method of claim 1 , wherein the second RTT is estimated based on one or more prior server side TCP sessions.

8. A non-transitory computer readable medium with computer readable program code embodied therewith for reducing memory usage of a service gateway buffer resident in a memory module of a service gateway for a Transmission Control Protocol (TCP) proxy session between a client and a server by adjusting server side session transmission time to reduce buffer usage, the computer readable program code configured to:
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, the first RTT being estimated based at least on an average of one or more prior server side TCP sessions with the server;
determine a second RTT for the client side TCP session of the TCP proxy session between the service gateway and the client, the second RTT being estimated based at least on an average of one or more prior client side TCP sessions with the client;
compare the first RTT with the second RTT by the service gateway;
determine that the second RTT exceeds the first RTT;
compare a difference between the second RTT and the first RTT:
in response to determining that the difference is above a predetermined threshold, calculate a desired RTT based on the second RTT, the calculation based at least in part on a memory capacity of server side receive buffer; and
set a timer by the service gateway according to the calculated desired RTT, wherein the TCP acknowledgement for the server side TCP session is delayed until the service gateway determines that the timer expires.

9. The non-transitory computer readable medium of claim 8 , wherein the computer readable program code configured to determine whether the second RTT exceeds the first RTT and to calculate a desired RTT based on the second RTT are further configured to:
determine whether the second RTT exceeds the first RTT beyond a predetermined threshold; and
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.

10. The non-transitory computer readable medium of claim 8 , wherein the computer readable program code configured to calculate a desired RTT based on the second RTT is further configured to:
calculate the desired RTT as a percentage of the second RTT.

11. The non-transitory computer readable medium of claim 8 , wherein the computer readable program code configured to calculate a desired RTT based on the second RTT is further configured to:
calculate the desired RTT as the second RTT minus a predetermined value.

12. The non-transitory computer readable medium of claim 8 , where computer readable program code configured to set the timer according to the calculated desired RTT is further configured to:
receive a data packet from the server over the server side TCP session;
determine a need to send the TCP acknowledgement to the server; set a timer to the desired RTT; and
in response to an expiration of the timer, send the TCP acknowledgement to the server.

13. A system for reducing memory usage of a service gateway buffer for a Transmission Control Protocol (TCP) proxy session between a client and a server by adjusting server side session transmission time to reduce the buffer usage, the system comprising:
a service gateway comprising a processor, a memory module, and a server side receive buffer residing in the memory module, wherein a server side TCP session of the TCP proxy session is established between the service gateway and the server, and a client side TCP session of the TCP proxy session is established between the service gateway and the client, wherein the service gateway:
determines a first round trip time (RTT) for a server side TCP session of the TCP proxy session between the service gateway and the server the first RTT being estimated based on at least an average of one or more prior server side TCP sessions with the server;
determines a second RTT for the client side TCP session of the TCP proxy session between the service gateway and the client, the second RTT being estimated based at least on an average of one or more prior client side TCP sessions with the client;
compares the first RTT with the second RTT;
determines that the second RTT exceeds the first RTT;
compares a difference between the second RTT and the first RTT;
in response to determining that the difference is above a predetermined threshold, calculates a desired RTT based on the second RTT, the calculation based at least in part on a memory capacity of server side receive buffer; and
sets a timer according to the calculated desired RTT, wherein the TCP acknowledgement fo

Assignees

• A10 Networks Inc

Inventors

• Han Liang
• Cao Zhiruo

Classifications

• H04L67/42

  Electricity · mapped topic

• H04L43/0864

  Round trip delays · CPC title

• H04L43/16

  Threshold monitoring · CPC title

• H04L47/283 Primary

  in response to processing delays, e.g. caused by jitter or round trip time [RTT] · CPC title

• H04L69/16

  Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP] · CPC title