Automatic discovery and enforcement of service level agreement settings
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.
1. A method of automatically detecting service level agreement (SLA) settings for a network path between a data source device sending user packets to a data sink device comprising:
generating, at a traffic generator device, synthetic packets and inserting said synthetic packets on said network path along with said user packets at a level that exceeds a committed information rate (CIR) setting of said network path;
collecting, at a discovery device, at least two valid traffic samples from said network path, wherein said valid traffic sample comprises a sum of number of bytes of user packets and synthetic packets measured between two consecutive losses of synthetic packets; and
determining, at said discovery device, from the collected traffic samples the CIR enforced by said network.
2. The method of claim 1 in which said CIR is enforced by said network using a traffic shaper.
3. The method of claim 1 in which said CIR is enforced by said network using a policing function.
4. The method of claim 1 in which said SLA settings are detected during service activation of an Ethernet service associated with said network path.
5. The method of claim 1 in which said SLA settings are detected during in-service operation of an Ethernet service associated with said network path.
6. The method of claim 1 in which said count of the total number of bytes received is based on a sum of lengths in bytes of all user packets and synthetic packets received in said valid sample.
7. The method of claim 1 in which said synthetic packets include sequence numbers, and at least one of the corresponding first and second packet loss indications 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.
8. The method of claim 7 in which said corresponding second packet loss indication is used as an end timestamp of a current traffic sample and where the same packet loss indication is used as a begin timestamp of the next traffic sample.
9. The method of claim 1 in which said valid traffic sample includes:
a begin timestamp taken after the start of the sample, and
an end timestamp taken before the end of the sample.
10. The method of claim 1 in which the calculated traffic rate of a valid traffic sample is determined by dividing the total number of bytes received during said traffic sample by the difference between an end timestamp of said valid traffic sample and a begin timestamp of said valid traffic sample.
11. A system for automatically detecting service level agreement (SLA) settings for a network path between a data source device sending user packets to a data sink device comprising:
a traffic generator device to generate synthetic packets on said network path at a level that exceeds the CIR enforced by the network to detect a committed information rate CIR enforced by said network;
a discovery device collecting at least two valid traffic samples from said network path, wherein said valid traffic samples comprises a sum of number of bytes of user packets and synthetic packets measured between two consecutive losses of synthetic packets; and
said discovery device to determine from the collected traffic samples the CIR value enforced by said traffic shaping devices.
12. The method of claim 11 in which said CIR is enforced by said network using a traffic shaper.
13. The method of claim 11 in which said SLA settings are detected during service activation of an Ethernet service associated with said network path.
14. The method of claim 11 in which said SLA settings are detected during in-service operation of an Ethernet service associated with said network path.