System and method for measuring round trip times in a network using a TCP packet

• US 6,446,121 B1
• Filed: 05/26/1998
• Issued: 09/03/2002
• Est. Priority Date: 05/26/1998
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Honnur, Virupaksh, Bosteder, Dalen D., Shah, Dhaval N.
• Primary Examiner(s): Burgess, Glenton B.
• Assistant Examiner(s): SALAD, ABDULLAHI ELMI
• Application Number:
  US09/087,689
• Time in Patent Office: 1,561 Days
• Field of Search: 709/200, 709/224, 709/223, 709/238, 709/239, 709/226, 709/241, 709/203, 709/235, 709/229, 709/105, 709/219, 709/201, 370/253, 370/390
• 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]

Abstract

An embodiment of the present invention is a system and method for measuring round trip times in a network, such as the Internet, by utilizing a packet, such as a transmission control protocol (TCP) packet. The TCP packet may be a packet which is typically utilized during establishment of a reliable connection, such as a SYN or a SYN ACK. According to an embodiment of the present invention, a mirrored service is selected for a client by sending the TCP packet from an approximate location of each of the mirrored service to an approximate location of the client. A response is then received by each mirrored service from the approximate location of the client, and a round trip time for each mirrored service is measured from the time the TCP packet was sent to the time the response was received. The various round trip times of each mirrored service are compared with each other and a best round trip time, such as the shortest time, is selected. A mirrored service associated with the best round trip time is selected for use with the client.

Claims

1. A method for responding to a request for a host name comprising:

receiving the request for a host name from a source;

identifying a plurality of mirrored web sites associated with the host name;

for each of the plurality of mirrored web sites, performing at a time of receiving the request and prior to providing in response to the request address information associated with the host name;

sending a first packet from the mirrored website to the source;

receiving a second packet at the mirrored website in response to the first packet; and

determining a round trip packet travel time for the mirrored website by comparing a first time associated with sending the first packet with a second time associated with the receiving of the second packet; and

selecting one of the plurality of mirrored web sites based at least in part on the respective round trip packet travel times determined for the plurality of mirrored websites.

2. A method as in claim 1, further comprising

sending, to the source, information identifying the one of said plurality of mirrored web sites selected.

3. A method as in claim 2, wherein the information comprises an IP address.

4. A method as in claim 1, wherein the source is a local domain name server.

5. A system for responding to a request for a host name comprising:

a processor; and

memory storing code executable by said processor, said code comprising;

computer code that receives the request for a host name from a source;

computer code that identifies a plurality of mirrored web sites associated with the host name;

computer code that, for each of the plurality of mirrored web sites, at a time of receiving the request and prior to providing in response to the request address information associated with the host name;

sends a first packet to the source;

receives a second packet in response to the first packet; and

determines a round trip packet travel time for the mirrored website by comparing a first time associated with sending the first packet and a second time associated with the receiving of the second packet; and

computer code that selects one of the plurality of mirrored web sites based at least in part on the respective round trip packet travel times determined for the plurality of mirrored websites.

6. A computer program product for responding to a request for a host name, the computer program product comprising:

computer code that receives the request for a host name from a source;

computer code that identifies a plurality of mirrored web sites associated with the host name;

computer code that, for each of the plurality of mirrored web sites, at a time of receiving the request and prior to providing in response to the request address information associated with the host name;

sends a SYN packet to the source;

receives a second packet in response to the first packet; and

determines a round trip packet travel time for the mirrored website by comparing a first time associated with sending the first packet with a second time associated with the receiving of the second packet; and

computer code that selects one of the plurality of mirrored web sites based at least in part on the respective round trip packet travel times determined for the plurality of mirrored websites; and

a computer readable medium that stores the codes.

7. The computer program product of claim 6, wherein the computer readable medium is selected from the group consisting of CD-ROM, floppy disk, tape, flash memory, system memory, hard drive, and data signal embodied in a carrier wave.