Method and apparatus for timeout reduction and improved wireless network performance by delay injection

• US 20060104313A1
• Filed: 04/20/2005
• Published: 05/18/2006
• Est. Priority Date: 11/18/2004
• Status: Active Grant

• Current Assignee: Alcatel-Lucent USA, Inc. (Nokia Corporation)
• Original Assignee: Alcatel-Lucent USA, Inc. (Nokia Corporation)
• Inventors: Haner, Mark, Leung, Kin K., Klein, Thierry Etienne
• Granted Patent: US 7,821,924 B2
• Time in Patent Office: Days
• US Class Current: 370/517
• CPC Class Codes: H04L 1/188 Time-out mechanisms
• 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 47/32 by discarding or delaying data units, e.g. packets or frames
• 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
• CPC Class Codes: H04W 80/06 Transport layer protocols, e.g. TCP [Transport Control Protocol] over wireless transmission control protocol/Internet protocol [TCP/IP] or user datagram protocol [UDP] H04L69/16

Abstract

A technique for avoiding spurious TCP timeouts through delay injection which requires no modification of, or access to, the TCP protocol itself. More particularly, injection of additional random delay or jitter at some point in a packet'"'"'s roundtrip path across a wireless communications network is employed so as to increase the variance in round trip times, without significantly increasing the average value thereof. Spurious TCP timeouts are avoided through the artificial delay injection which occurs at a network element along the communications path and without modification of, or requiring access to, the TCP protocol. Further, the injection of artificial delay is applied on a transaction-by-transaction basis. That is, the decision to inject, or not inject, the artificial delay as well as the value of the injected delay are applied to each TCP connection or TCP flow.

Claims

1. A method for reducing timeouts across a communications network, said communications network having a plurality of communications links which exchange packets in accordance with a transmission control protocol (TCP), said method comprising the steps of:

monitoring said packets exchanged across a particular one communications link of said plurality of communications links, said one communications link connecting a TCP receiver and a TCP sender;

injecting, at a network element along said communications link, a delay into said TCP packets being exchanged across said communications link, said delay being injected at a fixed time interval and having a fixed length; and

wherein said delay injecting occurs without modification of said TCP protocol, and said injected delay avoids at least one TCP timeout across said communications network.

2. The method of claim 1, wherein said packets are acknowledgement packets transmitted from said TCP receiver to said TCP sender.

3. The method of claim 2, wherein said communications network is a wireless network, said TCP receiver is a wireless handset and said TCP sender is a server.

4. The method of claim 1, wherein said injecting step further comprises the step of:

selecting a set of tunable parameters, said tunable parameters including a delay injection probability p, and a value of an injected delay D₀, said selecting of said tunable parameter being made so as to maximize an achieved TCP-level throughput, and wherein said delay injecting is made as a function of said selected delay injection probability p, and said selected value of said injected delay D₀.

5. A method for reducing timeouts across a communications network, said communications network having a plurality of communications links which exchange packets in accordance with a transmission control protocol (TCP), said method comprising the steps of:

monitoring said packets exchanged across a particular one communications link of said plurality of communications links, said one communications link connecting a TCP receiver and TCP sender;

injecting, at a network element along said communications link, a delay into said TCP packets being exchanged across said communications link, said delay being injected at a random time interval and having a fixed length; and

wherein said delay injecting occurs without modification of said TCP protocol, and said injected delay avoids at least one TCP timeout across said communications network.

6. The method of claim 5, wherein said packets are acknowledgement packets transmitted from said TCP receiver to said TCP sender.

7. The method of claim 6, wherein said communications network is a wireless network, said TCP receiver is a wireless handset and said TCP sender is a server.

8. The method of claim 5, wherein said injecting step further comprises the step of:

selecting a set of tunable parameters, said tunable parameters including a delay injection probability p, and a value of an injected delay D₀, wherein said selecting is made as a function of at least one performance statistic of said communications network, and wherein said delay injecting is made as a function of said selected delay injection probability p, and said selected value of said injected delay D₀.

9. The method of claim 5, wherein said injecting step further comprises the step of:

selecting a set of tunable parameters, said tunable parameters including a delay injection probability p, and a value of an injected delay D₀, said selecting of said tunable parameter being made so as to maximize an achieved TCP-level throughput, and wherein said delay injecting is made as a function of said selected delay injection probability p, and said selected value of said injected delay D₀.

10. A method for reducing timeouts across a communications network, said communications network having a plurality of communications links which exchange packets in accordance with a transmission control protocol (TCP), said method comprising the steps of:

monitoring said packets exchanged across a particular one communications link of said plurality of communications links, said one communications link connecting a TCP receiver and a TCP sender;

injecting, at a network element along said communications link, a delay into said TCP packets being exchanged across said communications link, said delay being injected at a random time interval and having a random length; and

wherein said delay injecting occurs without modification of said TCP protocol, and said injected delay avoids at least one TCP timeout across said communications network.

11. The method of claim 10, wherein said packets are acknowledgement packets transmitted from said TCP receiver to said TCP sender.

12. The method of claim 11, wherein said communications network is a wireless network, said TCP receiver is a wireless handset and said TCP sender is a server.

13. The method of claim 10, wherein said injecting step further comprises the step of:

selecting a set of tunable parameters, said tunable parameters including a delay injection probability p, and a value of an injected delay D₀, said selecting of said tunable parameter being made so as to maximize an achieved TCP-level throughput, and wherein said delay injecting is made as a function of said selected delay injection probability p, and said selected value of said injected delay D₀.

14. The method of claim 10, wherein said injecting step further comprises the step of:

selecting a set of tunable parameters, said tunable parameters including a delay injection probability p, and a value of an injected delay D₀, wherein said selecting is made as a function of at least one performance statistic of said communications network, and wherein said delay injecting is made as a function of said selected delay injection probability p, and said selected value of said injected delay D₀.

15. A transmission control protocol (TCP) network apparatus comprising:

a processor;

at least one memory coupled to said processor; and

wherein said processor is operative to perform the steps of;

monitoring a plurality of packets exchanged across a particular one TCP communications link of a plurality of TCP communications links, said one communications link connecting a TCP receiver and a TCP sender; and

injecting a delay into said packets being exchanged across said TCP communications link, such that said delay injecting occurs without modification of a TCP protocol governing said packets exchanged across said TCP communications link, and said injected delay avoids at least one TCP timeout across a communications network supporting said TCP communications link and connected with said TCP network apparatus.

16. The TCP network apparatus of claim 15, wherein said delay is injected at a fixed time interval and having a fixed length.

17. The TCP network apparatus of claim 15, wherein said delay is injected at a random time interval and having a fixed length.

18. The TCP network apparatus of claim 15, wherein said delay being injected at a random time interval and having a random length.

19. The method of claim 15, wherein said injecting step further comprises the step of:

selecting a set of tunable parameters, said tunable parameters including a delay injection probability p, and a value of an injected delay D₀, said selecting of said tunable parameter being made so as to maximize an achieved TCP-level throughput, and wherein said delay injecting is made as a function of said selected delay injection probability p, and said selected value of said injected delay D₀.

20. An article of manufacture comprising a machine-readable medium storing one or more programs for use in reducing timeouts across a communications network, said communications network having a plurality of communications links which exchange packets in accordance with a transmission control protocol (TCP), said one or more programs when executed performing the steps of:

monitoring said packets exchanged across a particular one communications link of said plurality of communications links, said one communications link connecting a TCP receiver and a TCP sender;

injecting a delay, at a network element connected along said communications link at an intermediary point between said TCP receiver and said TCP sender, into said TCP packets being exchanged across said communications link at a predefined interval, and wherein said delay injecting occurs without modification of said TCP protocol, and said injected delay avoids at least one TCP timeout across said communications network.