Method for measuring unidirectional transmission characteristics such as packet propagation time, fluctuations in propagation time and results derivable therefrom, in a telecommunications network

• US 20040024550A1
• Filed: 08/11/2003
• Published: 02/05/2004
• Est. Priority Date: 09/19/2000
• Status: Active Grant

• Current Assignee: Deutsche Telekom AG
• Original Assignee: Deutsche Telekom AG
• Inventors: Doerken, Heinrich, Mende, Joachim
• Granted Patent: US 8,160,835 B2
• Time in Patent Office: Days
• US Class Current: 702/79
• CPC Class Codes: G04G 7/00 Synchronisation radio-controlled time-pieces G04R
• CPC Class Codes: H04J 3/0644 External master-clock
• CPC Class Codes: H04L 43/0829 Packet loss
• CPC Class Codes: H04L 43/0858 One way delays
• CPC Class Codes: H04L 43/087 Jitter
• CPC Class Codes: H04L 43/0888 Throughput
• CPC Class Codes: H04L 43/106 using time related information in packets, e.g. by adding timestamps
• CPC Class Codes: H04L 43/16 Threshold monitoring
• CPC Class Codes: H04L 43/50 Testing arrangements
• CPC Class Codes: H04L 69/28 Timers or timing mechanisms used in protocols

Abstract

The present invention is directed to a method for measuring unidirectional transmission properties, such as packet delay (Dnetwork), delay-time fluctuations (tjitter), and results derivable therefrom, in a telecommunications network (10), such as the Internet, an intranet, or the like. In the telecommunications network, a plurality of switching devices (12 through 22) and other devices (34, 36, 38) are interconnected via transmission lines (24). Between at least two measuring computers (26, 28), test packets are transmitted from the first measuring computer (26) via a measurement path (32) to the second measuring computer (28). The first measuring computer (26) records the departure time (t1) of the outgoing test packet. This clock time is transmitted along with the test packet. The second measuring computer (28) records the arrival time (t2) of the test packet. In a subtraction operation between the departure time from the first measuring computer (26) and the arrival time in the second measuring computer (28), the delay time (Dnetwork) of the test packet, the measuring result, is determined. In accordance with the present invention, to determine the measuring result, the two measuring computers (26, 28) are synchronized in time by satellite systems (30), for example by a GPS (global positioning system), in that the clock time is continuously transmitted to both measuring computers (26, 28).

Claims

1. A method for measuring unidirectional transmission properties, such as packet delay (Dnetwork), delay-time fluctuations (tjitter), and results derivable therefrom, in a telecommunications network (10), such as the Internet, an intranet, or the like, between at least two measuring computers (26, 28), where test packets are transmitted from a first measuring computer (26) to a another, second measuring computer (28), the first measuring computer (26) recording the departure time (t1) of the outgoing test packet, and transmitting this clock time along with the test packet, and the second measuring computer (28) recording the arrival time (t2) of the test packet, and, in a subtraction operation between the departure time from the first measuring computer (26) and the arrival time in the second measuring computer (28), the delay time (Dnetwork) of the test packet, [i.e.,] the measuring result, being determined,

wherein to determine the measuring result, the two measuring computers (26, 28) are synchronized in time by satellite systems (30), for example by a GPS (global positioning system), in that the clock time is continuously transmitted by a plurality of satellites to both measuring computers (26, 28).

2. The method as recited in claim 1 or 2,

wherein the measuring result is stored in a database (36).

3. The method as recited in claim 2,

wherein every, in particular authorized, user can query the measuring results from the database (36) via the telecommunications network (10).

4. The method as recited in claim 3,

wherein an identifier is stored for the authorized user in the database (36), and upon transmission of the identifier by the authorized user, the querying of the measuring results from the database (36) is released.

5. The method as recited in one of claims 2 through 4,

wherein the measuring results are transmitted from the second measuring computer (28) via the telecommunications network (10) to the database (36).

6. The method as recited in one of the preceding claims,

wherein to ascertain delay-time fluctuations (tjitter), at least two test packets are sent consecutively from the first measuring computer (26) to the second measuring computer (28).

7. The method as recited in one of the preceding claims,

wherein test packets are continuously transmitted from the first measuring computer (26) to the second measuring computer 28), in particular, the time interval from departure of the test packets from the first measuring computer varying.

8. The method as recited in one of the preceding claims,

wherein data and clock information is assigned to the measuring results and is stored accordingly in the database (36), so that it is discernible at which points in time which measuring results occurred.

9. The method as recited in one of the preceding claims,

wherein for every measuring computer (26, 28), the computer-specific time component (Dsoft, CVsrc, CVdest) required by the software and the operating system of this measuring computer (26, 28) to handle the test packet in the measuring computer (26, 28) until the departure or arrival time is ascertained, is determined.

10. The method as recited in claim 8,

wherein the computer-specific time component (Dsoft) is subtracted from the delay time, and the result corresponds to the true delay time (Dnetwork), the true delay time (Dnetwork) then forming the measuring result.

11. The method as recited in one of the preceding claims,

wherein a control computer (34) is provided, which, via the telecommunications network (10), controls the measuring computers (26, 28) for determining the measuring result, such as establishing the measuring connections, initiating transfer of the measuring results to the database (36), determining the status of the measuring computers (26, 28), and the like.

12. The method as recited in claim 11,

wherein no test packets are recorded during the transmission of data from one measuring computer (26, 28) to the control computer (34).

13. The method as recited in one of the preceding claims,

wherein besides the delay time (Dnetwork) and the delay-time fluctuations (tjitter), losses occurring during transmission of the test packets are also ascertained and are stored accordingly as measuring results in the database (36).

14. A device for implementing the method as recited in one of the preceding claims.