System and method for determining network conditions

• US 6,731,600 B1
• Filed: 02/08/1999
• Issued: 05/04/2004
• Est. Priority Date: 02/08/1999
• Status: Expired due to Term

• Current Assignee: Intel Corporation
• Original Assignee: RealNetworks, Inc.
• Inventors: Hefta-Gaub, Bradley D., Patel, Sujal M., Rosedale, Philip, Ayars, Jeffrey M., Stammen, Dale R., Agarwal, Rahul, Haight, Peter S.
• Primary Examiner(s): Nguyen, Chau
• Assistant Examiner(s): HYUN, SOON D
• Application Number:
  US09/246,506
• Time in Patent Office: 1,912 Days
• Field of Search: 370/468, 370/235, 370/229, 370/230, 370/389, 370/392, 370/401, 370/252
• US Class Current: 370/230
• CPC Class Codes: H04L 43/062 related to network traffic
• CPC Class Codes: H04L 43/0852 Delays
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/11 Identifying congestion
• CPC Class Codes: H04L 47/18 End to end
• CPC Class Codes: H04L 47/283 in response to processing delays, e.g. caused by jitter or round trip time [RTT]

Abstract

A system and a method determine network conditions. The system includes a server computer and a client computer. The server computer is configured to transmit data packets comprising a data object from the server computer to the client computer. The client computer includes a transmission latency detector and a transmission bandwidth detector. The transmission latency detector uses transmission time and receipt time values to determine the changes in time it takes selected portions of the data object to be transmitted from the server computer to the client computer. The transmission bandwidth detector uses identified back-to-back data packets to determine the transmission bandwidth between the server computer and the client computer.

Claims

1. A method of determining a transmission bandwidth of a network communications link between a client and a server the method comprising:

receiving at the client, a first data packet transmitted from the server via the network communications link, the first data packet having an identifier indicating that the first data packet is being sent by the server back-to-back with respect to a second data packet;

receiving at the client the second data packet transmitted by the server via the network communications link; and

determining a transmission bandwidth of the network communication link, responsive to the receipt of the data packets by the client.

8. The method of claim 1, additionally comprising applying a compensation factor which compensates for the granularity of a system clock.

9. The method of claim 1, additionally comprising reporting to a software module the determined transmission bandwidth.

10. The method of claim 1, wherein the data packets collectively provide a streaming media presentation.

11. The method of claim 1, wherein the determined transmission bandwidth is an estimation of a maximum transmission bandwidth between the server and the client.

22. The method of claim 1, wherein the first data packet and the second data packet are received via a modem.

2. A method of determining a transmission bandwidth of a communications link, the method comprising:

receiving in a client computer, a first data packet transmitted via the communications link;

identifying a first point in time upon the completion of the receipt of the first data packet;

receiving in the client computer a second data packet transmitted via the communications link;

identifying a second point in time upon the completion of the receipt of the second data packet;

determining a difference between the first point in time and the second point in time;

determining a quantity of data in the second data packet; and

determining the transmission bandwidth based on the determined difference and the determined quantity.

3. The method of claim 2, wherein determining the transmission bandwidth based on the determined difference and the determined quantity includes the act of applying the following equation:

4. The method of claim 2, additionally comprising applying a compensation factor which compensates for the granularity of a system clock.

5. The method of claim 2, additionally comprising reporting to a software module the determined transmission bandwidth.

6. The method of claim 2, additionally comprising:

receiving one or more back-to-back packets subsequent to the receipt of the first data packet and the second data packet, each of the back-to-back packets including a third data packet and a fourth data packet;

identifying a third point in time for each of the back-to-back packets corresponding to the completion of the receipt of the third data packet in each of the back-to-back packets;

identifying a fourth point in time for each of the back-to-back packets corresponding to the completion of the receipt of the fourth data packet in each of the back-to-back packets;

determining differences between the third point in time and the fourth point in time with respect to each of the back-to-back packets;

determining a quantity of data in each of the four data packets; and

determining the transmission bandwidth based on the determined differences between the third and fourth points in time and the determined quantities of data in each of the fourth data packets.

7. The method of claim 6, wherein determining the transmission bandwidth based on the determined differences and the determined quantities includes the act of applying the following equation:

12. A method of determining network conditions, the method comprising:

receiving a plurality data packets from a server computer via a communication link; and

determining a transmission latency responsive to the receipt of the one of the plurality of data packets, wherein the latency identifies a duration of time that it takes to receive a data packet from the server in relation to a previously received data packet and the latency is determined based upon application of the following equation;

13. The method of claim 12, additionally comprising:

accessing a timestamp in each of the plurality of data packets, each timestamp approximately identifying a point in time when the server computer began transmitting the respective data packet; and

modifying each of the timestamps to account for any clock skew between a clock of the server computer and a clock of a receiving computer.

14. A system for determining a transmission bandwidth of a communication link between a server computer and a client computer, the system comprising:

a packet receiver which receives a first data packet followed by a second data packet transmitted to the client from the server via the communication link;

the first data packet including a back-to-back packet identifiers indicating that the first data packet is being transmitted back-to-back relative to the second data packet; and

a transmission bandwidth detector which determines a transmission bandwidth associated with the communication link, responsive to the receipt of the first and second data packets by the packet receiver.

15. A system for determining a transmission bandwidth, the system comprising:

a packet receiver which receives a first data packet followed by a second data packet from a first computer transmitted via a communication link; and

a transmission bandwidth detector which determines a transmission bandwidth associated with the communication link, responsive to the receipt of the first and second data packets by the packet receiver, wherein the second data packet was sent back-to-back relative to the first packet, and based upon the following equation;

16. The system of claim 15, wherein the transmission bandwidth detector estimates the amount of available transmission bandwidth between the server and the client.

17. The system of claim 15, wherein the transmission bandwidth detector reports the transmission bandwidth to the packet receiver.

18. The system of claim 15, wherein the transmission bandwidth detector estimates a maximum transmission bandwidth between the server and the client.

23. The system of claim 15, additionally comprising a modem for receiving the data packets.

19. A system for determining a latency in data communication, the system comprising:

a packet receiver which receives one or more data packets from a first computer; and

a latency detector which determines changes in latency in data communication from the first computer to a second computer, responsive to the receipt of the data packets by the packet receiver, wherein the latency identifies a duration of time it takes to receive a data packet from the first computer relative to a previously received data packet, and

wherein the latency detector applies the following equation;

20. The system of claim 19, wherein the transmission latency detector reports the transmission latency to the packet receiver.

21. The system of claim 20, wherein the data packets collectively provide a streaming media presentation.

24. A program storage device storing instructions that when executed performs the method comprising:

receiving a first data packet and a second data packet via a communication link, receiving an identifier that indicates that the first and second data packets are transmitted back-to-back; and

determining a transmission bandwidth of the communication link in response to the receipt of the data packets.

25. The program storage device of claim 24, additionally comprising instructions to receive the first data packet and the second data packet via a modem.

26. A method of determining a transmission bandwidth of a communications link, the method comprising:

receiving a first data packet transmitted via the communications link;

receiving a second data packet transmitted via the communications link, wherein the first data packet has an identifier that indicates that the second data packet is sent successively following the first data packet; and

determining a transmission bandwidth of the communication link, responsive to the receipt of the data packets.

27. The method of claim 26, additionally comprising applying a compensation factor which compensates for the granularity of a system clock.

28. The method of claim 26, additionally comprising reporting to a software module the determined transmission bandwidth.