Monitoring Quality of a Packet Flow in Packet-Based Communication Networks

• US 20090225671A1
• Filed: 03/06/2008
• Published: 09/10/2009
• Est. Priority Date: 03/06/2008
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Sagy, Ravid, Filsfils, Clarence, Arbel, Yuki, Keohane, Michael, Shemesh, Oren
• Granted Patent: US 7,948,910 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04L 43/00 Arrangements for monitoring or testing data switching networks
• CPC Class Codes: H04L 43/0829 Packet loss
• CPC Class Codes: H04L 43/0852 Delays
• CPC Class Codes: H04L 43/12 Network monitoring probes

Abstract

A communication system includes multiple routers interconnected by a packet-based communication network. Each of the routers includes a monitoring application that monitors quality of one or more packet flows during each of multiple successive monitoring periods. For each of the packet flows, the monitoring application determines quality metrics based on information obtained from transport headers of packets.

Claims

1. A system comprising:

a plurality of routers interconnected by a packet-based network, at least one of the routers comprising;

a network interface, the network interface operable to receive a plurality of packets, make a plurality of forwarding decisions, and transmit the packets according to the forwarding decisions;

a table identifying one or more packet flows, each of the packet flows comprising a plurality of packets;

a monitoring application, the monitoring application operable, for each of the packet flows during each of a plurality of successive monitoring periods, to inspect one or more transport headers of the packets, compile a quantity metric, and determine one or more quality metrics, the quality metrics for a current monitoring period determined according to a previous difference between the quantity metric and a constant, the constant defined by the amount of packets expected to be consumed by a media presentation application during a monitoring period, for a previous monitoring period and a current difference between the quantity metric and the constant for a current monitoring period; and

a memory for storing the quality metrics.

2. The system of claim 1, further comprising a plurality of deep packet inspection probes.

3. The system of claim 1, wherein a difference between a quantity metric and a constant for a monitoring period is positive, zero, or negative.

4. The system of claim 3, wherein if the previous difference is negative and the current difference is positive, a quality metric for the current monitoring period is defined by the lesser of the sum of the previous difference and the current difference or zero, and the next difference for the next monitoring period is defined by the greater of the sum of the previous difference and the current difference or zero;

if the previous difference is positive and the current difference is negative, a quality metric for the current monitoring period is defined by the greater of the sum of the previous difference and the current difference or zero, and the next difference for the next monitoring period is defined by the lesser of the sum of the previous difference and the current difference or zero;

if either the previous difference or the current difference is zero, the quality metric for the current monitoring period is defined by the previous difference, and the next difference for the next monitoring period is defined by the current difference; and

if both the previous difference and the current difference are negative or if both the previous difference and the current difference are positive, the quality metric for the current monitoring period is defined by the previous difference, and the next difference for the next monitoring period is defined by the current difference.

5. The system of claim 1, further comprising a central management application, the central management application operable to receive one or more reports from the routers.

6. The system of claim 1, wherein the quality metrics comprise a media loss rate, the media loss rate defined by an amount of packets lost during a monitoring period.

7. The system of claim 1, wherein the constant is defined either manually by a theoretical rate of the packet flows or automatically by auto-learning of an actual rate of the packet flows.

8. An apparatus comprising:

a network interface, the network interface operable to receive a plurality of packets, make a plurality of forwarding decisions, and transmit the packets according to the forwarding decisions;

a table identifying one or more packet flows, each of the packet flows comprising a plurality of packets;

a monitoring application, the monitoring application operable, for each of the packet flows during each of a plurality of successive monitoring periods, to inspect one or more transport headers of the packets, compile a quantity metric, and determine one or more quality metrics, the quality metrics for a current monitoring period determined according to a previous difference between the quantity metric and a constant, the constant defined by the amount of packets expected to be consumed by a media presentation application during a monitoring period, for a previous monitoring period and a current difference between the quantity metric and the constant for a current monitoring period; and

a memory for storing the quality metrics.

9. The apparatus of claim 8, wherein a difference between a quantity metric and a constant for a monitoring period is positive, zero, or negative.

10. The apparatus of claim 9, wherein if the previous difference is negative and the current difference is positive, a quality metric for the current monitoring period is defined by the lesser of the sum of the previous difference and the current difference or zero, and the next difference for the next monitoring period is defined by the greater of the sum of the previous difference and the current difference or zero;

if the previous difference is positive and the current difference is negative, a quality metric for the current monitoring period is defined by the greater of the sum of the previous difference and the current difference or zero, and the next difference for the next monitoring period is defined by the lesser of the sum of the previous difference and the current difference or zero;

if either the previous difference or the current difference is zero, the quality metric for the current monitoring period is defined by the previous difference, and the next difference for the next monitoring period is defined by the current difference; and

if both the previous difference and the current difference are negative or if both the previous difference and the current difference are positive, the quality metric for the current monitoring period is defined by the previous difference, and the next difference for the next monitoring period is defined by the current difference.

11. The apparatus of claim 8, wherein the constant is defined either manually by a theoretical rate of the packet flows or automatically by auto-learning of an actual rate of the packet flows.

12. The apparatus of claim 8, further comprising a reporting application, the reporting application operable to report, for each of the packet flows during each of the successive monitoring periods, one or more quality metrics to a central management application.

13. The apparatus of claim 8, further comprising an administrator interface, the administrator interface operable to provide an administrator with access to the quality metrics.

14. The apparatus of claim 8, wherein the quality metrics comprise a media loss rate, the media loss rate defined by an amount of packets lost during a monitoring period.

15. A method comprising:

receiving a plurality of packets, making a plurality of forwarding decisions, and transmitting the packets according to the forwarding decisions;

identifying one or more packet flows, each of the packet flows comprising a plurality of packets;

for each of the packet flows during each of a plurality of successive monitoring periods, inspecting one or more transport headers of the packets, compiling a quantity metric, and determining one or more quality metrics, the quality metrics for a current monitoring period determined according to a previous difference between the quantity metric and a constant, the constant defined by the amount of packets expected to be consumed by a media presentation application during a monitoring period, for a previous monitoring period and a current difference between the quantity metric and the constant for a current monitoring period; and

storing the quality metrics.

16. The method of claim 15, wherein a difference between a quantity metric and a constant for a monitoring period is positive, zero, or negative.

17. The method of claim 16, wherein if the previous difference is negative and the current difference is positive, a quality metric for the current monitoring period is defined by the lesser of the sum of the previous difference and the current difference or zero, and the next difference for the next monitoring period is defined by the greater of the sum of the previous difference and the current difference or zero;

if the previous difference is positive and the current difference is negative, a quality metric for the current monitoring period is defined by the greater of the sum of the previous difference and the current difference or zero, and the next difference for the next monitoring period is defined by the lesser of the sum of the previous difference and the current difference or zero;

if either the previous difference or the current difference is zero, the quality metric for the current monitoring period is defined by the previous difference, and the next difference for the next monitoring period is defined by the current difference; and

if both the previous difference and the current difference are negative or if both the previous difference and the current difference are positive, the quality metric for the current monitoring period is defined by the previous difference, and the next difference for the next monitoring period is defined by the current difference.

18. The method of claim 15, wherein the constant is defined either manually by a theoretical rate of the packet flows or automatically by auto-learning of an actual rate of the packet flows.

19. The method of claim 15, further comprising reporting, for each of the packet flows during each of the successive monitoring periods, the quality metrics to a central management application.

20. The method of claim 15, wherein the quality metrics comprise a media loss rate, the media loss rate defined by an amount of packets lost during a monitoring period.