SYSTEM AND METHOD FOR ESTIMATION OF ROUND TRIP TIMES WITHIN A TCP BASED DATA NETWORK
First Claim
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1. A monitoring system for monitoring the round trip time of data packets travelling between a first node and second node within a packet based network, the system comprising:
- a. A first module configured to interrogate traffic originating from the first node and to extract and store sequence numbers from individual packet headers;
b. A timer module configured to initiate a timer on extraction of sequence numbers; and
c. A second module configured to interrogate acknowledgements from the second node relating to the traffic sent, and to stop the timer on identification of an acknowledgment relating to a stored sequence number so as to provide an estimate of the round trip time of packets travelling between the first and second nodes.
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Abstract
A system and method for estimation of round trip times (RTTs) within a TCP based data network is described. The system provides for a passive monitoring of the network round-trip latency by simply observing existing TCP connections in operation. In this way, it is possible to measure RTT out to a remote site without having to send any traffic to that site with the result that there is no impact on the network, and it is possible to estimate what production traffic is experiencing.
73 Citations
12 Claims
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1. A monitoring system for monitoring the round trip time of data packets travelling between a first node and second node within a packet based network, the system comprising:
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a. A first module configured to interrogate traffic originating from the first node and to extract and store sequence numbers from individual packet headers; b. A timer module configured to initiate a timer on extraction of sequence numbers; and c. A second module configured to interrogate acknowledgements from the second node relating to the traffic sent, and to stop the timer on identification of an acknowledgment relating to a stored sequence number so as to provide an estimate of the round trip time of packets travelling between the first and second nodes. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of passively monitoring the round trip time of data packets travelling between a first node and second node within a packet based network, the method comprising:
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a. Interrogating traffic originating from the first node so as to extract and store sequence numbers from individual packet headers; b. Initiating a timer on extraction of a sequence number from a packet header; c. Interrogating acknowledgements from the second node relating to the traffic sent to that node so as to extract acknowledgement numbers from individual packet headers; d. Comparing the acknowledgement numbers with the stored sequence numbers; e. Stopping the timer for a specific sequence number on receipt of an acknowledgement number for the sequence number of that timer; and f. Using the elapsed time on that timer for an estimation of the round trip time of packets between the first and second nodes. - View Dependent Claims (10, 12)
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11. An article of manufacture with a computer usable medium having computer readable program instructions embodied therein, the program instructions being configured to passively monitor the round trip time of data packets travelling between a first node and second node within a packet based network, the program instructions causing a processor to execute the following:
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a. Interrogate traffic originating from the first node so as to extract and store sequence numbers from individual packet headers; b. Initiate a timer on extraction of a sequence number from a packet header; c. Interrogate acknowledgements from the second node relating to the traffic sent to that node so as to extract acknowledgement numbers from individual packet headers; d. Compare the acknowledgement numbers with the stored sequence numbers; e. Stop the timer for a specific sequence number on receipt of an acknowledgement number for the sequence number of that timer; and f. use the elapsed time on that timer for an estimation of the round trip time of packets between the first and second nodes.
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Specification