Network condition capture and reproduction

• US 8,027,267 B2
• Filed: 11/06/2007
• Issued: 09/27/2011
• Est. Priority Date: 11/06/2007
• Status: Active Grant

• Current Assignee: Avaya Incorporated
• Original Assignee: Avaya Incorporated
• Inventors: Rao, Balaji Sathyanarayana, Diethorn, Eric J., Denby, Lorraine, Meloche, Jean
• Primary Examiner(s): Yao; Kwang B
• Assistant Examiner(s): Liu; Jung
• Application Number:
  US11/935,515
• Publication Number:
  US 20090116397A1
• Time in Patent Office: 1,421 Days
• Field of Search: 370/250, 370/252, 370/408, 370/465, 709/224
• US Class Current: 370/252
• CPC Class Codes: H04L 41/145 involving simulating, designing, planning or modelling of a network
• CPC Class Codes: H04L 43/0852 Delays
• CPC Class Codes: H04L 43/106 using time related information in packets, e.g. by adding timestamps

Abstract

A network condition capture and reproduction technique captures measurement data characterizing network conditions at a given time between first and second endpoint devices of a network, and utilizes the captured measurement data in a network impairment device to reproduce the network conditions at a later time and possibly in a different place.

Claims

1. A method comprising:

receiving, by a first network element, first measurement data and second measurement data from a first endpoint device and a second endpoint device in a network, respectively, wherein;

(i) the first measurement data is generated based on departure timestamps and arrival timestamps of a first plurality of packets received at an ingress and an egress of the first endpoint device, and

(ii) the second measurement data is generated based on departure timestamps and arrival timestamps of a second plurality of packets received at an egress and an ingress of the second endpoint device;

processing, by the first network element, the first measurement data and the second measurement data to form one-way transit times d₁, d₂, . . . , d_n that characterizes network conditions at a given time between the first endpoint device and the second endpoint device;

storing, in a first variable delay buffer of the first network element, a first ordered sequence of packets received from the first endpoint device, wherein each packet of the first ordered sequence of packets is to be transmitted by the first network element based on respective one-way transit times d₁, d₂, . . . , d_n;

adjusting, by the first network element, the one-way transit times d₁, d₂, . . . , d_n to offset additional delays, Δ

, that are attributable to reproducing the network conditions, wherein the one-way transit times d₁, d₂, . . . , d_n are adjusted by the first network element to produce an adjusted one-way transit times d₁−

Δ

, d₂−

Δ

, . . . , d_n−

Δ

; and

transmitting, by the first network element, each packet of the first ordered sequence of packets stored in the first variable delay buffer based on the adjusted one-way transit times d₁−

Δ

, d₂−

Δ

, . . . , d_n−

Δ

to the second endpoint device.

2. The method of claim 1 wherein a first interface and the first variable delay buffer of the first network element are for receiving the first ordered sequence of packets from the first endpoint device;

wherein a second interface and a second variable delay buffer of the first network element are for receiving a second ordered sequence of packets from the second endpoint device; and

wherein the first interface and the first variable delay buffer are different from the second interface and the second variable delay buffer.

3. The method of claim 1 wherein the first network element is coupled to a communications path of the network;

and

wherein the first network element is coupled to the communications path at a location that is between the first endpoint device and the second endpoint device for reproducing the network conditions.

4. The method of claim 1 wherein the first network element is coupled to a communications path that is external to the network;

wherein the first network element is coupled to the communications path at a location that is between a third endpoint device and a fourth endpoint device for reproducing the network conditions that occurred between the first network element and the second network element; and

wherein the first endpoint device and the second endpoint device are different from the third endpoint device and the fourth endpoint device.

5. The method of claim 1 wherein the first network element is configured to operate in at least one of a listening mode and a conversational mode.

6. The method of claim 5 further comprising:

in the listening mode, selecting, by the first network element, a voice sample from a plurality of voice samples stored at the first network element, wherein each voice sample in the plurality of voice samples are different; and

transmitting, by the first network element to the second endpoint device, the selected voice sample based on the respective one-way transit times d₁−

Δ

, d₂−

Δ

, . . . , d_n−

Δ

.

7. The method of claim 5 further comprising:

(i) receiving, by the first network element, a second ordered sequence of packets from a third endpoint device located at a first geographic location,

(ii) transmitting, by the first network element, each packet of the second ordered sequence of packets to a fourth endpoint device based on the one-way transit times d₁−

Δ

, d₂−

Δ

, . . . , d_n−

Δ

; and

(iii) receiving, by the first network element, a third ordered sequence of packets from the fourth endpoint device located at a second geographic location, and

(iv) transmitting, by the first network element, each packet of the third ordered sequence of packets to the third endpoint device based on the one-way transit times d₁−

Δ

, d₂−

Δ

, . . . , d_n−

Δ

; and

wherein the first geographic location is in a geographic time zone that is different from the second geographic location.

8. The method of claim 1 further comprising:

receiving, by the first network element, third measurement data from the second endpoint device;

wherein the third

measurement data is computed by subtracting a first arrival timestamp from each subsequent arrival timestamp of a third plurality of packets to form relative timestamps t₁, t₂, . . . , t_n;

wherein the relative timestamps t₁, t₂, . . . , t_n are different from;

(i) the one-way transit times d₁, d₂, . . . , d_n, and

(ii) the adjusted one-way transit times d₁−

Δ

, d₂−

Δ

, . . . , d_n−

Δ

.

9. The method of claim 8 wherein the first network element is configured with a base one-way delay d_b, and wherein the base one-way delay d_b is a delay of the first packet in the third plurality of packets.

10. The method of claim 9 further comprising:

storing, by the first network element, a second ordered sequence of packets received from the second endpoint device in a second variable delay buffer of the first network element.

11. The method of claim 8 further comprising:

adjusting, by the first network element, the relative timestamps t₁, t₂, . . . , t_n, to produce adjusted relative timestamps t₁−

Δ

, t₂−

Δ

, . . . , t_n−

Δ

; and

transmitting, by the first network element, each packet of the second ordered sequence of packets stored in the second variable delay buffer based on the adjusted relative timestamps t₁−

Δ

, t₂−

Δ

, . . . , t_n−

Δ

to the first endpoint device;

wherein the adjusted relative timestamps t₁−

Δ

, t₂−

Δ

, . . . , t_n−

Δ

is different from;

(i) times d₁, d₂, . . . , d_n, and

(ii) times d₁−

Δ

, d₂−

Δ

, . . . , d_n−

Δ

.

12. The method of claim 1 further comprising:

dropping, by the first network element, a packet having a delay that is associated with a lost packet when reproducing the network conditions.

13. The method of claim 12 wherein the dropped packet is indexed by the first network element based on a Real-time Transport Protocol (RTP) header of the dropped packet.

14. The method of claim 1 wherein processing the one-way transit times d₁, d₂, . . . , d_n requires clocks of the first endpoint device and the second endpoint device be synchronized with one another.