Sampling test of network performance

• US 7,990,887 B2
• Filed: 02/22/2006
• Issued: 08/02/2011
• Est. Priority Date: 02/22/2006
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Horn, Lior Z, Zangiri, Benny, Sidi, Moshe, Cidon, Israel
• Primary Examiner(s): Ngo; Ricky
• Assistant Examiner(s): SAMUEL, DEWANDA A
• Application Number:
  US11/359,723
• Publication Number:
  US 20070195707A1
• Time in Patent Office: 1,987 Days
• Field of Search: 370/252, 370/241, 370/431, 370/458, 370/459, 370/241.1, 370/242, 370/244, 370/245, 370/248, 370/238, 370/253, 379/1.01, 379/22, 379/22.03, 379/22.04, 379/22.05
• US Class Current: 370/253
• CPC Class Codes: H04L 43/50 Testing arrangements

Abstract

A method for testing a communication network includes transmitting a flow of test packets over a path through the network. The flow includes a series of bursts of the test packets separated by intervals having an interval duration, each burst comprising a sequence of the test packets and having a burst duration less than the interval duration. Arrival characteristics of the test packets in the flow are measured at a receiving end of the path. The arrival characteristics include at least one of a packet loss characteristic, a packet delay characteristic, and a packet jitter characteristic. A quality defect in the network is detected based on the measured arrival characteristics.

Claims

1. A method for testing a communication network, comprising:

generating a flow of test packets, the flow comprising a series of bursts of the test packets separated by intervals having an interval duration, each burst comprising a sequence of the test packets and having a burst duration less than the interval duration, wherein generating the flow comprises generating a test packet having a packet size and data rate chosen according to a predetermined codec used in Voice over Internet Protocol (VoIP);

transmitting the flow of test packets over a path through the network;

measuring arrival characteristics of the test packets in the flow at a receiving end of the path, the arrival characteristics comprising at least one of a packet loss characteristic, a packet delay characteristic, and a packet jitter characteristic; and

detecting a quality defect in the network based on the measured arrival characteristics;

said detecting a quality defect by computing a statistical feature of said arrival characteristics of the test packets over said series of bursts while disregarding the arrival characteristics of an initial test packet in each burst;

computing, for the predetermined codec, a Mean Opinion Score (MOS) for each burst based on the arrival characteristics of the test packets thereof;

determining the percentage of bursts in the series for which a corresponding MOS is above a predetermined threshold; and

determining whether call quality over the communication network is inadequate based on a percentage of bursts in the series for which the corresponding MOS is lower than the predetermined threshold.

2. The method according to claim 1, wherein the burst duration is no more than one tenth of the interval duration.

3. The method according to claim 1, wherein the burst duration is no more than 1 sec.

4. The method according to claim 1, wherein each burst comprises no more than fifty of the test packets.

5. A method for testing a communication network, comprising:

generating a burst of test packets, the burst comprising a sequence of no more than fifty of the test packets and having a burst duration no greater than 1 sec, wherein generating the flow comprises generating a test packet having a packet size and data rate chosen according to a predetermined codec used in Voice over Internet Protocol (VoIP);

transmitting the burst of test packets over a path through the network;

measuring arrival characteristics of the test packets in the burst at a receiving end of the path, the arrival characteristics comprising at least one of a packet loss characteristic, a packet delay characteristic, and a packet jitter characteristic; and

detecting a quality defect in the network based on the measured arrival characteristics;

said detecting a quality defect comprising by a statistical feature of said arrival characteristics of the test packets over said series of bursts while disregarding the arrival characteristics of an initial test packet in each burst;

computing, for the predetermined codec, a Mean Opinion Score (MOS) for each burst based on the arrival characteristics of the test packets thereof;

determining the percentage of bursts in the series for which a corresponding MOS is above a predetermined threshold; and

determining whether call quality over the communication network is inadequate based on a percentage of bursts in the series for which the corresponding MOS is lower than the predetermined threshold.

6. Apparatus for testing a communication network, comprising:

first and second traffic agents, which are coupled to respective end points of a path through the network; and

a testing center, which is coupled to instruct at least the first traffic agent to transmit a flow of test packets having a packet size and data rate chosen according to a predetermined codec used in Voice over Internet Protocol (VoIP) over the path through the network, the flow comprising a series of bursts of the test packets separated by intervals having an interval duration, each burst comprising a sequence of the test packets and having a burst duration less than the interval duration, and to instruct at least the second traffic agent to measure arrival characteristics of the test packets in the flow at a receiving end of the path, the arrival characteristics comprising at least one of a packet loss characteristic, a packet delay characteristic, and a packet jitter characteristic,

said testing center being adapted to detect a quality defect in the network based on the measured arrival characteristics; and

said testing center being arranged to;

compute a statistical feature of the arrival characteristics of the test packets over the series of the bursts while disregarding the arrival characteristics of an initial test packet in each burst;

compute, for the predetermined codec, a Mean Opinion Score (MOS) for each burst based on the arrival characteristics of the test packets thereof;

determine the percentage of bursts in the series for which a corresponding MOS is above a predetermined threshold; and

determine whether call quality over the communication network is inadequate based on a percentage of bursts in the series for which the corresponding MOS is lower than the predetermined threshold.

7. Apparatus for testing a communication network, comprising:

first and second traffic agents, which are coupled to respective end points of a path through the network; and

a testing center, which is coupled to instruct at least the first traffic agent to transmit a burst of test packets having a packet size and data rate chosen according to a predetermined codec used in Voice over Internet Protocol (VoIP) over a path through the network, the burst comprising a sequence of no more than fifty of the test packets and having a burst duration no greater than 1 sec, and to instruct at least the second traffic agent to measure arrival characteristics of the test packets in the burst at a receiving end of the path, the arrival characteristics comprising at least one of a packet loss characteristic, a packet delay characteristic, and a packet jitter characteristic,

said testing center being adapted to detect a quality defect in the network based on the measured arrival characteristics;

said testing center being arranged to;

compute a statistical feature of the arrival characteristics of the test packets over the series of the bursts while disregarding the arrival characteristics of an initial test packet in each burst;

compute, for the predetermined codec, a Mean Opinion Score (MOS) for each burst based on the arrival characteristics of the test packets thereof;

determine the percentage of bursts in the series for which a corresponding MOS is above a predetermined threshold; and

determine whether call quality over the communication network is inadequate based on a percentage of bursts in the series for which the corresponding MOS is lower than the predetermined threshold.

8. A computer software product for testing a communication network in conjunction with first and second traffic agents, which are coupled to respective end points of a path through the network, the product comprising a non-transitory computer-readable medium in which program instructions are stored, which instructions, when read by a computer, cause the computer to instruct at least the first traffic agent to transmit a flow of test packets having a packet size and data rate chosen according to a predetermined codec used in Voice over Internet Protocol (VoIP) over the path through the network, the flow comprising a series of bursts of the test packets separated by intervals having an interval duration, each burst comprising a sequence of the test packets and having a burst duration less than the interval duration, and to instruct at least the second traffic agent to measure arrival characteristics of the test packets in the flow at a receiving end of the path, the arrival characteristics comprising at least one of a packet loss characteristic, a packet delay characteristic, and a packet jitter characteristic, the instructions causing the computer to detect a quality defect in the network based on the measured arrival characteristics;

the instructions causing the computer to;

compute a statistical feature of the arrival characteristics of the test packets over the series of the bursts while disregarding the arrival characteristics of an initial test packet in each burst;

compute, for the predetermined codec, a Mean Opinion Score (MOS) for each burst based on the arrival characteristics of the test packets thereof;

determine the percentage of bursts in the series for which a corresponding MOS is above a predetermined threshold; and

determine whether call quality over the communication network is inadequate based on a percentage of bursts in the series for which the corresponding MOS is lower than the predetermined threshold.

9. A computer software product for testing a communication network in conjunction with first and second traffic agents, which are coupled to respective end points of a path through the network, the product comprising a non-transitory computer-readable medium in which program instructions are stored, which instructions, when read by a computer, cause the computer to instruct at least the first traffic agent to transmit a burst of test packets having a packet size and data rate chosen according to a predetermined codec used in Voice over Internet Protocol (VoIP) over a path through the network, the burst comprising a sequence of no more than fifty of the test packets and having a burst duration no greater than 1 sec, and to instruct at least the second traffic agent to measure arrival characteristics of the test packets in the burst at a receiving end of the path, the arrival characteristics comprising at least one of a packet loss characteristic, a packet delay characteristic, and a packet jitter characteristic, the instructions causing the computer to detect a quality defect in the network based on the measured arrival characteristics;

the instructions causing the computer to;

compute a statistical feature of the arrival characteristics of the test packets over the series of the bursts while disregarding the arrival characteristics of an initial test packet in each burst;

compute, for the predetermined codec, a Mean Opinion Score (MOS) for each burst based on the arrival characteristics of the test packets thereof;

determine the percentage of bursts in the series for which a corresponding MOS is above a predetermined threshold; and

determine whether call quality over the communication network is inadequate based on a percentage of bursts in the series for which the corresponding MOS is lower than the predetermined threshold.