Methods and apparatus for determining the performance of a server

• US 7,216,164 B1
• Filed: 10/09/2002
• Issued: 05/08/2007
• Est. Priority Date: 10/09/2002
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: O'Toole, James W. Jr., Whitmore, Bryan
• Primary Examiner(s): Vaughn; William
• Assistant Examiner(s): MANIWANG, JOSEPH R
• Application Number:
  US10/267,936
• Time in Patent Office: 1,672 Days
• Field of Search: 709/223, 709/224
• US Class Current: 709/224
• CPC Class Codes: H04L 41/5009 Determining service level performance parameters or violations of service level contracts, e.g. violations of agreed response time or mean time between failures [MTBF]
• CPC Class Codes: H04L 41/5083 wherein the managed service relates to web hosting
• CPC Class Codes: H04L 41/5096 wherein the managed service relates to distributed or central networked applications
• CPC Class Codes: H04L 43/00 Arrangements for monitoring or testing data switching networks
• CPC Class Codes: H04L 43/0811 by checking connectivity
• CPC Class Codes: H04L 43/0817 by checking functioning
• CPC Class Codes: H04L 67/1001 for accessing one among a plurality of replicated servers
• CPC Class Codes: H04L 67/1008 based on parameters of servers, e.g. available memory or workload monitoring of computer activity G06F11/30
• CPC Class Codes: H04L 67/101 based on network conditions
• 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

Abstract

Mechanisms and techniques provide a method for determining the performance of a server, based upon a connection characteristic of a connection between the server and a client. The connection characteristic, such as the window size of the server, provides information regarding the performance or capacity of the server. Variation between the connection characteristic and a preferred connection characteristic is used by a data communications device, for example, to determine the performance of the server. Based upon the variation in the connection characteristic, the data communications device is then able to direct incoming content requests to other servers in communication with a network, as required.

Claims

1. In a data communications device, a method for determining the performance of a server, connected with a client, comprising the steps of:

monitoring a connection characteristic of a connection between the server and the client;

detecting a variance in the connection characteristic relative to a preferred connection characteristic; and

determining the performance of the server based upon the variance in the connection characteristic;

wherein the connection is a Transmission Control Protocol connection and wherein the step of monitoring comprises monitoring a Transmission Control Protocol window size from the server; and

wherein the step of monitoring further comprises;

receiving a series of Transmission Control Protocol window sizes transmitted from the server;

determining a trend for the Transmission Control Protocol window size of the server based upon the window sizes transmitted from the server; and

setting a preferred Transmission Control Protocol window size for the server based upon the trend for the window size;

wherein determining the trend includes comparing the connection characteristic of the connection over multiple successive communication transaction cycles between the server to the client to identify when the performance of the server increases as indicated by most recently received connection characteristics being nearer in value to the preferred connection characteristic, the connection characteristic being a window size generated by the server and sent to the client for purposes of limiting an amount of data sent by the client to the server.

2. The method of claim 1 wherein the step of detecting comprises:

comparing the preferred connection characteristic with an incoming connection characteristic; and

determining a variance between the preferred connection characteristic and the incoming connection characteristic.

3. The method of claim 1 wherein the step of determining further comprises determining a capacity of the server based upon the variance between the preferred connection characteristic and an incoming connection characteristic.

4. The method of claim 1 further comprising the steps of:

detecting a content request between a second client and the server;

determining the performance of the server; and

directing the content request to a second server, based upon the performance of the server.

5. The method of claim 1 wherein the step of detecting comprises:

comparing the preferred Transmission Control Protocol window size with an incoming Transmission Control Protocol window size; and

determining a variance in Transmission Control Protocol window size of the server.

6. The method of claim 1 wherein the step of determining further comprises determining a capacity of the server based upon the variance between the preferred Transmission Control Protocol window size and an incoming Transmission Control Protocol window size.

7. The method of claim 6 further comprising determining a decrease in the variance, the decrease in variance indicating an increase in the capacity of the server.

8. The method of claim 1 further comprising the steps of:

receiving a content request from a client, and

adjusting a last-transmitted connection characteristic from the server prior to receiving an updated connection characteristic and based upon the content request; and

wherein the step of detecting comprises detecting a variance in the last-transmitted connection characteristic relative to a preferred connection characteristic.

12. The data communications device of claim 1 wherein the controller is further configured to:

detect a content request between a second client and the server;

determine a reduction in the performance of the server; and

direct the content request to a second server, based upon the performance of the server.

9. A data communications device comprising:

at least one communications interface;

a controller; and

an interconnection mechanism coupling the at least one communications interface and the controller;

wherein the controller is configured to;

monitor a connection characteristic of a connection between a server and a client;

detect a variance in the connection characteristic relative to a preferred connection characteristic; and

determine the performance of the server based upon the variance in the connection characteristic;

wherein the data communication device is disposed at an intermediate network node on a respective network path between the client and the server, the controller being configured to;

receive first communications originating from the server and forward the received first communications to the client and, in a reverse direction, receive second communications originated by the client and forward the second communications to the server; and

wherein the controller further configured to;

receive a series of connection characteristics transmitted from the server;

determine a trend for the connection characteristic of the server based upon each connection characteristic transmitted from the server; and

set the preferred connection characteristic for the server based upon the trend for the connection characteristic; and

wherein determining the trend includes comparing the connection characteristic of the connection over multiple successive communication transaction cycles between the server to the client to identify when the performance of the server increases as indicated by most recently received connection characteristics being nearer in value to the preferred connection characteristic, the connection characteristic being a window size generated by the server and sent to the client for purposes of limiting an amount of data sent by the client to the server.

10. The data communications device of claim 9 wherein the controller is further configured to:

compare the preferred connection characteristic with an incoming connection characteristic; and

determine a variance between the preferred connection characteristic and the incoming connection characteristic.

11. The data communications device of claim 9 wherein the controller is further configured to determine a capacity of the server based upon a variance between the preferred connection characteristic and an incoming connection characteristic.

13. The data communications device of claim 9 wherein the connection is a Transmission Control Protocol connection and the controller is further configured to monitor a Transmission Control Protocol window size from the server.

14. The data communications device of claim 13 wherein the controller is further configured to:

receive a series of Transmission Control Protocol window sizes transmitted from the server;

determine a trend for the Transmission Control Protocol window size of the server based upon the window sizes transmitted from the server; and

set a preferred Transmission Control Protocol window size for the server based upon the trend for the window size.

15. The data communications device of claim 14 wherein the controller is further configured to:

compare the preferred Transmission Control Protocol window size with an incoming Transmission Control Protocol window size; and

determine a decrease in Transmission Control Protocol window size of the server.

16. The data communications device of claim 14 wherein the controller is further configured to determine a capacity of the server based upon a variance between the preferred Transmission Control Protocol window size and an incoming Transmission Control Protocol window size.

17. The data communications device of claim 16 wherein the controller is further configured to determine a decrease in the variance to indicate an increase in the capacity of the server.

18. The data communications device of claim 9, the controller is further configured to:

receive a content request from a client, and

adjust a last-transmitted connection characteristic from the server prior to receiving an updated connection characteristic and based upon the content request; and

when detecting, the controller is configured to detect a variance in the last-transmitted connection characteristic relative to a preferred connection characteristic.

19. A data communications device as in claim 9, wherein the controller in the data communication device is configured to:

receive a data packet originated by the server which is sent to the client, the data packet including a content portion as well as a window size indicating to the client how much data can be received by the server from the client on a subsequent client data transfer;

inspect the data packet to identify the window size specified by the server; and

determine a difference between the window size and a preferred window size to identify a relative ability of the server to handle requests by other clients.

20. A data communications device as in claim 9, wherein the controller is configured to:

receive data packets originated by each of multiple servers for transmission to respective clients, each of the data packets including a content portion as well as a window size indicating to a corresponding client how much data can be received by a respective server from the corresponding client on a subsequent client data transfer;

inspect the data packets to identify window sizes specified by the servers for multiple requests;

determine a difference between window sizes and respective preferred window sizes associated with the servers to identify relative abilities of the servers to handle data requests; and

based on the relative abilities of the servers to handle the data requests, utilizing feedback to regulate a flow of data from the servers to the respective clients.

21. A data communications device as in claim 9, wherein the connection characteristic is a window size associated with a communication session between a first client and the server, the controller configured to:

recognize a reduction in the window size associated with the communication session, the reduction indicating that the server has become closer to being overloaded; and

based on recognizing the reduction in the window size, initiate redirection of a second client request directed to the server to another server for servicing to prevent the server from being overloaded.

22. A data communication device as in claim 21, wherein the controller is configured to:

perform in-band examination of respective data packets associated with the communication session to identify when the window size specified by the server decreases indicating that the server nears an overload condition in which the server is unable to efficiently handle the second client request.

23. A data communication device as in claim 9, wherein the controller is configured to:

monitor connection characteristics of successive responses from the client to determine a respective performance of the server;

compare the connection characteristics with the preferred connection characteristic to determine if the server is overloaded with requests and has reached its capacity to receive requests;

if the comparison of the connection characteristic of the server with the preferred connection characteristic indicates that the server has reached its capacity to service requests, redirecting incoming content requests to other servers.

24. A computer program product having a computer-readable medium including computer program logic encoded thereon that, when performed on a processor in a computerized device having a coupling of a memory, a processor, and at least one communications interface provides a method for performing the operations of:

monitoring a connection characteristic of a connection between the server and the client and a server;

detecting a variance in the connection characteristic relative to a preferred connection characteristic; and

determining the performance of the server based upon the variance in the connection characteristic;

wherein monitoring the connection characteristic includes;

receiving a series of connection characteristics transmitted from the server;

determining a trend for the connection characteristic of the server based upon each connection characteristic transmitted from the server; and

setting the preferred connection characteristic for the server based upon the trend for the connection characteristic; and

wherein determining the trend includes comparing the connection characteristic of the connection over multiple successive communication transaction cycles between the server to the client to identify when the performance of the server increases as indicated by most recently received connection characteristics being nearer in value to the preferred connection characteristic, the connection characteristic being a window size generated by the server and sent to the client for purposes of limiting an amount of data sent by the client to the server.

25. A data communications device comprising:

at least one communications interface;

a controller; and

an interconnection mechanism coupling the at least one communications interface and the controller;

wherein the controller is configured to produce a means for determining the performance of a server connected with a client, such means including;

means for monitoring a connection characteristic of a connection between the server and the client and a server;

means for detecting a variance in the connection characteristic relative to a preferred connection characteristic; and

means for determining the performance of the server based upon the variance in the connection

wherein means for monitoring the connection characteristic includes;

means for receiving a series of connection characteristics transmitted from the server;

means for determining a trend for the connection characteristic of the server based upon each connection characteristic transmitted from the server; and

means for setting the preferred connection characteristic for the server based upon the trend for the connection characteristic; and

wherein means for determining the trend includes means for comparing the connection characteristic of the connection over multiple successive communication transaction cycles between the server to the client to identify when the performance of the server increases as indicated by most recently received connection characteristics being nearer in value to the preferred connection characteristic, the connection characteristic being a window size generated by the server and sent to the client for purposes of limiting an amount of data sent by the client to the server.

26. In a data communications device, a method for determining the performance of a server, connected with a client, comprising:

monitoring a connection characteristic of a connection between the server and the client;

detecting a variance in the connection characteristic relative to a preferred connection characteristic;

detecting a duration of time between the variance in the connection characteristic relative to a preferred connection characteristic; and

determining the performance of the server based upon the duration of time between changes in the connection characteristic;

wherein monitoring the connection characteristic includes;

receiving a series of connection characteristics transmitted from the server;

determining a trend for the connection characteristic of the server based upon each connection characteristic transmitted from the server; and

setting the preferred connection characteristic for the server based upon the trend for the connection characteristic; and

wherein determining the trend includes comparing the connection characteristic of the connection over multiple successive communication transaction cycles between the server to the client to identify when the performance of the server increases as indicated by most recently received connection characteristics being nearer in value to the preferred connection characteristic, the connection characteristic being a window size generated by the server and sent to the client for purposes of limiting an amount of data sent by the client to the server.

27. A data communications device comprising:

at least one communications interface;

a controller; and

an interconnection mechanism coupling the at least one communications interface and the controller;

wherein the controller is configured to;

monitor a connection characteristic of a connection between the server and the client;

detect a variance in the connection characteristic relative to a preferred connection characteristic;

detect a duration of time between the variance in the connection characteristic relative to a preferred connection characteristic; and

determine the performance of the server based upon the duration of time between changes in the connection characteristic;

wherein the controller is further configured to;

receive a series of connection characteristics transmitted from the server;

determine a trend for the connection characteristic of the server based upon each connection characteristic transmitted from the server;

set the preferred connection characteristic for the server based upon the trend for the connection characteristic; and

compare the connection characteristic of the connection over multiple successive communication transaction cycles between the server to the client to identify when the performance of the server increases as indicated by most recently received connection characteristics being nearer in value to the preferred connection characteristic, the connection characteristic being a window size generated by the server and sent to the client for purposes of limiting an amount of data sent by the client to the server.