Measuring burst rate and burst size in ATM network virtual connections
First Claim
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1. An instrument for measuring the size and rate of bursts of cells in an ATM communication network, each cell comprising a header portion including information corresponding to a virtual connection to which said cell belongs, and a payload portion, said instrument comprising:
- means for connection to a pathway of a stream of cells flowing in said network,cell filter means for comparing at least a portion of said header portion of each cell to information identifying a virtual connection of interest, and for providing a first signal responsive to detection of a cell in a monitored stream of cells belonging to said virtual connection of interest, andmeans for monitoring said first signal as a function of time, to determine the size and rate of bursts of cells belonging to said virtual connection of interest.
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Abstract
A test instrument for measuring the rate and size of bursts of cells received at a given node of an ATM network with respect to a particular virtual connection includes a cell filter for identifying cells belonging to the virtual connection. The "leaky bucket" algorithm is implemented for determining conformity with contractual performance standards, and for delineating the bursts.
50 Citations
28 Claims
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1. An instrument for measuring the size and rate of bursts of cells in an ATM communication network, each cell comprising a header portion including information corresponding to a virtual connection to which said cell belongs, and a payload portion, said instrument comprising:
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means for connection to a pathway of a stream of cells flowing in said network, cell filter means for comparing at least a portion of said header portion of each cell to information identifying a virtual connection of interest, and for providing a first signal responsive to detection of a cell in a monitored stream of cells belonging to said virtual connection of interest, and means for monitoring said first signal as a function of time, to determine the size and rate of bursts of cells belonging to said virtual connection of interest. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for measuring the size and rate of bursts of cells in an ATM communication network, each cell comprising a header portion including information corresponding to virtual connection to which said cell belongs, and a payload portion, said method comprising the steps of:
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connecting a test instrument to a pathway of a stream of cells flowing in said network, said instrument comprising cell filter means; supplying information identifying a virtual connection of interest to said instrument; comparing at least a portion of said header portion of each cell to information identifying a virtual connection of interest to thereby identify cells belonging to said virtual connection of interest; providing a first signal responsive to detection of a cell belonging to said virtual connection of interest; and monitoring said first signal as a function of time, to determine the size and rate of bursts of cells belonging to said virtual connection of interest. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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16. A method for measuring the size of bursts of cells with respect to a particular virtual connection established in an asynchronous transfer mode communications network, comprising the steps of:
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connecting a test instrument to a portion of the traffic flow path through a node in said network; operating said instrument to identify cells received at said node as a function of their respective virtual connection; determining the peak cell rate (PCR) of the virtual connection to be tested; monitoring the operation of an accumulator for measuring the time available for transmission of cells by the node with respect to that particular virtual connection, said accumulator implementing a cell rate control algorithm, according to which (1) 1/PCR seconds are added to the accumulator upon reception of each cell pertaining to a particular virtual connection, and (2) time is subtracted from a positive value stored in the accumulator as time elapses; determining that a burst has begun with respect to the particular virtual connection being monitored when a cell from that virtual connection is received at a time when the accumulator is empty; determining that a burst has ended when the value stored in the accumulator goes from a positive value to zero; and calculating the burst size (BS) as the number of cells counted during the burst as thus delineated. - View Dependent Claims (17, 18, 19, 20, 21, 22)
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23. An instrument for measuring the size of bursts of cells with respect to a particular virtual connection established in an asynchronous transfer mode communications network, comprising:
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means for establishing connection to a portion of the traffic flow path through a node in said network; means for identifying cells received at said node as a function of their respective virtual connection; means for determining the peak cell rate (PCR) of the virtual connection to be tested; accumulator means for monitoring time available for transmission of cells with respect to said virtual connection to be tested; means for implementing a cell rate control algorithm, whereby (1) 1/PCR in units of time is added to a value stored by the accumulator means upon reception of each cell pertaining to a particular virtual connection; and
(2) time slot is subtracted from any positive value stored in the accumulator means as time elapses;means for determining that a burst has begun when a cell of a message to be transmitted by said virtual connection to be tested is received when the value stored by the accumulator means is zero; means for determining that a burst has ended when the value stored in the accumulator means goes from a positive value to zero; and means for calculating the burst size (BS) as the number of cells counted during the burst as thus delineated. - View Dependent Claims (24, 25, 26, 27, 28)
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Specification