AUTOMATIC DISCOVERY AND ENFORCEMENT OF SERVICE LEVEL AGREEMENT SETTINGS

• US 20140071822A1
• Filed: 09/07/2012
• Published: 03/13/2014
• Est. Priority Date: 09/07/2012
• Status: Active Grant

• Current Assignee: Accedian Networks Inc. (Cisco Systems, Inc.)
• Original Assignee: Accedian Networks Inc. (Cisco Systems, Inc.)
• Inventors: Rochon, Steve
• Granted Patent: US 8,917,596 B2
• Time in Patent Office: Days
• US Class Current: 370/230.1
• CPC Class Codes: H04L 2012/6454 Random, e.g. Ethernet
• CPC Class Codes: H04L 41/0681 Configuration of triggering conditions
• CPC Class Codes: H04L 41/5009 Determining service level performance parameters or violations of service level contracts, e.g. violations of agreed response time or mean time between failures [MTBF]
• CPC Class Codes: H04L 41/5025 by proactively reacting to service quality change, e.g. by reconfiguration after service quality degradation or upgrade
• CPC Class Codes: H04L 41/5058 Service discovery by the service manager
• CPC Class Codes: H04L 43/024 by adaptive sampling
• CPC Class Codes: H04L 43/0829 Packet loss
• CPC Class Codes: H04L 43/0888 Throughput
• CPC Class Codes: H04L 47/21 using leaky-bucket
• CPC Class Codes: H04L 47/22 Traffic shaping
• CPC Class Codes: H04L 47/225 Determination of shaping rate, e.g. using a moving window
• CPC Class Codes: H04L 47/2425 for supporting services specification, e.g. SLA
• CPC Class Codes: H04L 47/29 using a combination of thresholds

Abstract

A method of automatically detecting the service level agreement settings in an Ethernet virtual circuit (EVC) carrying user packets comprises generating synthetic packets different from the user packets, on a data path in the EVC at a level sufficiently high to saturate the EVC. This accelerates the detection of actual effective values for the Committed Information Rate (CIR) and the Excess Information Rate (EIR) by triggering traffic shaping devices in the data path to enforce the CIR and EIR settings configured for those devices. A plurality of traffic samples are collected from the data path during a sampling period that is long enough to allow the collection of at least two valid traffic samples, where a valid traffic sample is the amount of user packets measured between two consecutive losses of synthetic packets. The CIR and EIR values enforced by the traffic shaping devices are determined from the collected samples.

Claims

1. A method of automatically detecting the service level agreement (SLA) settings in an Ethernet virtual circuit (EVC) carrying user packets, said method comprising

generating synthetic packets, different from the user packets, on a data path in said EVC at a level sufficiently high to saturate said EVC to accelerate the detection of actual effective values for CIR and EIR by triggering traffic shaping devices in said data path to enforce the CIR and EIR settings configured for said traffic shaping devices,

collecting a plurality of traffic samples from said data path during a sampling period that is long enough to allow the collection of at least two valid traffic samples, where a valid traffic sample is the amount of user packets measured between two consecutive losses of synthetic packets, and

determining from the collected traffic samples the effective CIR and EIR values enforced by said traffic shaping devices.

2. The method of claim 1 in which said CIR and EIR values are determined by analyzing each valid sample to determine the maximum number of consecutive data bytes in each valid traffic sample, which is the sum of the CIR and EIR, and then subtracting from that sum the smallest number of data bytes in any of the collected samples, which is CIR, to determine the remaining difference, which is EIR.

3. The method of claim 1 in which said SLA settings are detected by monitoring traffic flows in said EVC and determining the value of the CIR and EIR settings based on the amount of data that can be measured during a sampling period.

4. The method of claim 1 in which said SLA settings of said EVC are detected during service activation of said EVC.

5. The method of claim 1 in which said SLA settings of said EVC are detected during in-service operation of said EVC.

6. The method of claim 1 in which said sampling period is bound by a starting sampling timestamp and an ending sampling timestamp.

7. The method of claim 1 in which said valid traffic sample begins on a first packet loss indication and terminates on a second packet loss indication and includes a count of the total number of bytes received for the period between a pair of successive packet loss indications.

8. The method of claim 7 in which said number of bytes received is the sum of the length of all user packets and synthetic packets received in said valid sample.

9. The method of claim 7 in which said synthetic packets include sequence numbers, and a packet loss indication is determined by comparing the sequence number in a synthetic packet against an expected sequence number calculated as the value of the sequence number of the previous synthetic packet incremented by one.

10. The method of claim 7 in which said second packet loss indication is used as the ending timestamp of a current traffic sample and where the same packet loss indication is used as the begin timestamp of the next traffic sample.

11. The method of claim 7 in which said valid traffic sample includes:

a begin timestamp taken after the starting sampling timestamp of said sampling period, and

an end timestamp taken before the end sampling timestamp of said sampling period.

12. The method of claim 6 in which the calculated traffic rate of a valid traffic sample is determined by dividing the total number of bytes received during the said traffic sample by the difference between the end timestamp of said valid traffic sample and the begin timestamp of said valid traffic sample.

13. The method of claim 1 in which said calculated values of the CIR and the EIR are obtained by:

setting the value of the CIR of the said sampling period to zero,

setting the value of the EIR of the said sampling period to zero, and

analyzing the collected valid traffic samples obtained for the said sampling period.

14. The method of claim 7 in which the calculated values of the CIR and the EIR for said sampling period are obtained by:

determining whether the calculated value of the CIR is equal to zero and if it is, setting the value of the CIR to the value of the calculated traffic rate for the current traffic sample being analyzed;

otherwise, determining if the calculated traffic rate for said traffic sample is less than the calculated value of the CIR and if it is, calculating the effective value of the EIR by adding the value of the CIR to the value of the EIR and deducting the value of the calculated traffic rate for the current traffic sample being analyzed, and setting the value of the CIR to the value of the calculated traffic rate for said traffic sample;

otherwise, if the calculated traffic rate for said traffic sample is larger than the sum of the effective CIR and of the EIR, adjusting the effective value of the EIR for the said sampling period to the difference between the effective data rate for said sample and the effective CIR for said sampling period.