Network performance monitor

• US 20090222555A1
• Filed: 02/29/2008
• Published: 09/03/2009
• Est. Priority Date: 02/29/2008
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Qian, Tin, Ramarathinam, Aravind, Bishop, Michael
• Granted Patent: US 8,719,398 B2
• Time in Patent Office: Days
• US Class Current: 709/224
• CPC Class Codes: H04L 41/0896 Bandwidth or capacity management, i.e. automatically increasing or decreasing capacities flow or congestion control using dynamic resource allocation, e.g. in-call renegotiation, H04L47/76
• CPC Class Codes: H04L 41/5003 Managing SLA; Interaction between SLA and QoS
• CPC Class Codes: H04L 43/0864 Round trip delays
• CPC Class Codes: H04L 43/0882 Utilisation of link capacity

Abstract

A network performance monitor for a computer. The performance monitor maintains a baseline for communication paths between a networked computer and other networked computers connected. The network performance baseline is established and maintained by measuring and updating network performance parameters of the communication paths. The network performance parameters are updated using values obtained during time intervals when the communication path consumed a bandwidth approximately equal to its estimated bandwidth. If congestion is detected on the network or the network is underutilized, values of the network performance parameters obtained during that interval are not used to update the network performance parameters. Some performance parameters in the baseline, such as minimum and maximum bandwidth values may be updated by computing a moving average of each parameter. Asymmetric weight values for updating the moving average may be selected based on a direction of change of a value of a network parameter.

Claims

1. A method of monitoring network performance by maintaining at least one network performance parameter for at least one communication path between a first networked computer and least one other networked computer connected via a network, the method comprising:

obtaining at least one delay parameter for the at least one communication path over a time interval;

determining whether, during the time interval, communications on the at least one communication path consumed a bandwidth within a range of an estimated bandwidth; and

selectively updating at least one stored value of the at least one network performance parameter based on the obtained at least on delay parameter when it is determined that the communications consumed a bandwidth within the range.

2. The method of claim 1, wherein determining whether the communications on the path consumed the bandwidth within the range of the estimated bandwidth comprises determining whether the communications consumed a bandwidth that exceeds a threshold percentage of the estimated bandwidth.

3. The method of claim 2, wherein determining whether the communications consumed the bandwidth that exceeds the threshold percentage of the estimated bandwidth comprises determining whether a window set by a network stack had a size exceeding a threshold percentage of a value representing a product of the estimated bandwidth and an estimated round trip delay on the at least one communication path.

4. The method of claim 2, wherein determining whether the communications on the at least one communication path consumed the bandwidth within the range of the estimated bandwidth further comprises determining whether the at least one communication path is congested.

5. The method of claim 4, wherein determining whether the at least one communication path is congested comprises determining whether, during a second interval including the time interval, variation in Round Trip Time (RTT) on the at least one communication path exceeded a threshold.

6. The method of claim 1, wherein selectively updating the at least one stored value of the at least one network performance parameter comprises updating a network performance baseline.

7. The method of claim 1, wherein the at least one delay parameter comprises a bandwidth parameter and the bandwidth parameter is computed as a window size for the at least one communication path divided by a round trip time for the at least one communication path.

8. A method of maintaining a network performance baseline for at least one communication path between a first networked computer and least one other networked computer connected via a network, the method comprising:

maintaining a moving average of at least one network performance parameter during a plurality of intervals, the at least one network performance parameter representing an extreme value of a network performance value, the maintaining comprising, for each of the plurality of intervals;

obtaining, from a plurality of measurements of the network performance value parameter, an extreme value during the interval; and

updating the moving average of the at least one network performance parameter, the updating comprising computing a combination of the extreme value during the interval weighted by a first factor and a value of the moving average computed in a prior interval weighted by a second factor, at least one of the first factor and the second factor being selected based on the extreme value during the interval relative to the moving average computed in the prior interval.

9. The method of claim 8, wherein:

the extreme value comprises a maximum bandwidth;

the extreme value during the interval comprises a maximum bandwidth during the interval; and

the moving average computed in the prior interval comprises a moving average of the maximum bandwidth computed in the prior interval.

10. The method of claim 8, wherein:

the extreme value comprises a minimum bandwidth;

the extreme value during the interval comprises a minimum bandwidth during the interval; and

the moving average computed in the prior interval comprises a moving average of the minimum bandwidth computed in the prior interval.

11. The method of claim 9, wherein, when the maximum bandwidth during the interval is higher than the moving average of the maximum bandwidth computed in the prior interval, selecting a first ratio of the first and second factors, and, when the maximum bandwidth during the interval is not higher than the moving average of the maximum bandwidth computed in the prior interval, selecting a second ratio of the first and second factors, the first ratio being greater than the second ratio.

12. The method of claim 10, wherein, when the minimum bandwidth during the interval is lower than the moving average of the minimum bandwidth computed in the prior interval, selecting a first ratio of the first and second factors, and, when the minimum bandwidth during the interval is not lower than the moving average of the minimum bandwidth computed in the prior interval, selecting a second ratio of the first and second factors, the first ratio being greater than the second ratio.

13. The method of claim 8, further comprising maintaining a moving average of a mean bandwidth during the plurality of intervals, the maintaining comprising, for each of the plurality of intervals:

obtaining, from a plurality of measurements of bandwidth, the mean bandwidth; and

updating the moving average of the mean bandwidth, the updating comprising computing a combination of the mean bandwidth during the interval weighted by a first factor and a value of the moving average of the mean bandwidth computed in a prior interval weighted by a second factor.

14. The method of claim 8, further comprising obtaining, for each of the plurality of intervals, path usage parameters indicating usage of the at least one communication path, the path usage parameters comprising at least one or more of a round-trip-time, a variance of the round-trip-time, a duration of usage of the at least one communication path, amount of usage of the at least one communication path, a duration of time elapsed since last usage of the least one communication path.

15. A networked computer having stored thereon computer-executable modules for implementing a method of maintaining at least one network performance parameter for at least one communication path between the networked computer and least one other networked computer connected via a network, the computer-executable modules comprising:

a network stack providing at least one delay parameter for the at least one communication path over a time interval;

an interface between the network stack and at least one computer-executable module for receiving the least one delay parameter from the network stack and providing the least one delay parameter to the at least one computer-executable module; and

the at least one computer-executable module for;

determining of whether, during the time interval, communications on the at least one communication path consumed a bandwidth within a range of an estimated bandwidth; and

selectively updating of at least one stored value of at least one network performance parameter based on the obtained at least on delay parameter when it is determined that the communications consumed a bandwidth within the range.

16. The networked computer of claim 15, wherein the at least one computer-executable module is further for:

maintaining a moving average of the at least one network performance parameter during a plurality of intervals, the at least one network performance parameter representing an extreme measurement of a network performance, the maintaining comprising, for each of the plurality of intervals;

obtaining, from a plurality of measurements of the network performance parameter, an extreme value during the interval; and

updating the moving average of the at least one network performance parameter, the updating comprising computing a combination of the extreme value during the interval weighted by a first factor and a value of the moving average computed in a prior interval weighted by a second factor, at least one of the first factor and the second factor being selected based on the extreme value during the interval relative to the moving average computed in the prior interval.

17. The networked computer of claim 15, wherein determining whether the communications on the at least one communication path consumed the bandwidth within the range of the estimated bandwidth comprises determining whether the at least one communication path is congested.

18. The networked computer of claim 17, wherein determining whether the at least one communication path is congested comprises determining whether, during a second interval including the time interval, variation in at least one parameter relating to communication delay on the at least one communication path exceeded a threshold.

19. The networked computer of claim 15, wherein the extreme value comprises a maximum bandwidth, the extreme value during the interval comprises a maximum bandwidth during the interval and the moving average computed in the prior interval comprises a moving average of the maximum bandwidth computed in the prior interval.

20. The networked computer of claim 15, wherein the extreme value comprises a minimum bandwidth, the extreme value during the interval comprises a minimum bandwidth during the interval and the moving average computed in the prior interval comprises a moving average of the minimum bandwidth computed in the prior interval.