Method and apparatus for non-intrusive measurement of round trip delay in communications networks
First Claim
1. Apparatus for measuring round-trip delay time of identifiable data patterns traversing a plurality of points in a communication network by monitoring identifiable data patterns traversing said network during in-service operation, said apparatus comprising:
- first probe means, coupled to communication lines of said communication network and situated at a first point, for receiving identifiable data patterns representing information transmitted on said network, said first probe means comprising;
first time stamp means for generating a first probe time stamp representing a time at which each identifiable data pattern is received by said first probe means;
first identifier means for generating a pattern identifier for said each received identifiable data pattern based on data in said each identifiable data pattern; and
first buffer means for storing said first probe time stamps and said pattern identifier for each identifiable data pattern received at said first probe means;
second probe means, coupled to said communication lines and situated at a second point, for receiving identifiable data patterns representing information transmitted on said network, said second probe means comprising;
second time stamp means for generating a second probe time stamp representing a time at which each identifiable data pattern is received by said second probe means;
second identifier means for generating a pattern identifier for said each identifiable data pattern received by said second probe means and based on data in that identifiable data pattern; and
second buffer means for storing said second probe time stamps and said pattern identifiers for each identifiable data pattern received at said second probe means;
analysis means for analyzing data in said first and second buffer means and generating an analysis result; and
result means for determining from said analysis result a round-trip delay time for an identifiable data pattern traversing said first and second points;
wherein said first and second probe means, said analysis means and said result means collectively determine said round-trip delay time while said communication system is in-service processing identifiable data patterns during normal operating conditions.
5 Assignments
0 Petitions
Accused Products
Abstract
Measurement of round-trip delay or travel time in a communications network during in-service operation is accomplished by use of two probes, situated at respective points of interest along the communication network, and a processor. The probes receive identifiable data patterns normally transmitted over the communications network and generate a time stamp when each pattern arrives at or leaves the respective point. Each probe further generates a pattern identifier based on the data in the pattern and stores the identifier and time stamp as a pair in a buffer internal to each probe. Once the internal buffer contents exceed a predetermined amount of data, the processor receives the data from the buffers and matches pattern identifiers between the buffers to locate the departure and arrival time stamps of each pattern traveling between the probe points. Thereafter, the processor calculates an average of round-trip delay or travel times based on the departure and arrival time stamps of several patterns traveling in both directions between the probe points.
280 Citations
24 Claims
-
1. Apparatus for measuring round-trip delay time of identifiable data patterns traversing a plurality of points in a communication network by monitoring identifiable data patterns traversing said network during in-service operation, said apparatus comprising:
-
first probe means, coupled to communication lines of said communication network and situated at a first point, for receiving identifiable data patterns representing information transmitted on said network, said first probe means comprising; first time stamp means for generating a first probe time stamp representing a time at which each identifiable data pattern is received by said first probe means; first identifier means for generating a pattern identifier for said each received identifiable data pattern based on data in said each identifiable data pattern; and first buffer means for storing said first probe time stamps and said pattern identifier for each identifiable data pattern received at said first probe means; second probe means, coupled to said communication lines and situated at a second point, for receiving identifiable data patterns representing information transmitted on said network, said second probe means comprising; second time stamp means for generating a second probe time stamp representing a time at which each identifiable data pattern is received by said second probe means; second identifier means for generating a pattern identifier for said each identifiable data pattern received by said second probe means and based on data in that identifiable data pattern; and second buffer means for storing said second probe time stamps and said pattern identifiers for each identifiable data pattern received at said second probe means; analysis means for analyzing data in said first and second buffer means and generating an analysis result; and result means for determining from said analysis result a round-trip delay time for an identifiable data pattern traversing said first and second points; wherein said first and second probe means, said analysis means and said result means collectively determine said round-trip delay time while said communication system is in-service processing identifiable data patterns during normal operating conditions. - View Dependent Claims (2, 3, 4, 5, 6)
-
-
7. In a data communication network, a method for measuring transmission delay time of identifiable data patterns traversing the network past first and second monitor points, said method comprising the steps of:
-
(a) receiving identifiable data patterns at said first and second monitor points during in-service operation, of said communication system; (b) generating a time stamp for each received identifiable data patterns signifying a time of reception of that identifiable data pattern; (c) generating pattern identifiers from respective data in said received identifiable data patterns; (d) storing said time stamps and pattern identifiers for each received identifiable data pattern; (e) comparing said stored pattern identifiers and indicating a match when the same identifier is found to have been generated for an identifiable data pattern received at both said first and second monitor points; and (f) determining the time difference between time stamps for each matched identifier; wherein said steps (a)-(f) collectively determine the transmission delay time between said first and second monitor points while said communication system is in-service processing said identifiable data patterns during normal operating conditions. - View Dependent Claims (8, 9, 10, 11, 12, 13)
-
-
14. In an identifiable data pattern transmission network of the type wherein information is transmitted in the form of a series of identifiable digital data patterns between two or more spaced locations, apparatus for measuring transmission delay between first and second monitor points in said network using the data patterns transmitted during on-line operation of the network without requiring special test signals to be transmitted on the network or that the network be taken out of service to perform measurements, said apparatus comprising:
-
first and second probes connected to said network at said first and second monitor points, respectively, for receiving said data patterns as they are transmitted past said first and second monitor points; wherein each probe includes; time stamp means for generating a time stamp for each received data pattern representing a time at which that data pattern is received; identifier means responsive to each received data pattern for generating an identifier code derived as a function of specified bits in said data pattern to uniquely identify said each received data pattern; and a first storage buffer for storing in sequence the time stamp and identifier for data patterns received in said sequence from a first direction along said network; first comparator means for comparing data pattern identifiers stored in said first storage buffer of said first probe with data pattern identifiers stored in said first storage buffer of said second probe to locate a first direction match signifying the same identifier stored in both probes; and first computing means responsive to each first direction match located by said comparator means for computing a first direction difference between times represented by the time stamps for the matched identifiers, wherein said first direction difference is a measure of transmission delay in said first direction between said monitor points of the data pattern identified by the identifier of said each first direction match. - View Dependent Claims (15, 16, 17, 18, 19, 20)
-
-
21. The method of measuring round-trip transmission delay between first and second monitor points in an identifiable data pattern transmission network using identifiable data patterns transmitted during on-line operation of the network, and without requiring special test signals to be transmitted on the network or that the network be taken out of service to perform the measurements, said method comprising the steps of:
-
(a) measuring the delay between reception of at least one of said identifiable data pattern in the direction from said first monitor point to said second monitor point; (b) measuring the delay between reception of at least another of said identifiable data patterns in a direction from said second monitor point to said first monitor point; and (c) adding the delays measured in steps (a) and (b). - View Dependent Claims (22, 23, 24)
-
Specification