Non-Intrusive Service Activation Testing (SAT)?! It Is Possible!

SAT can be done in a way that’s non-intrusive. Imagine the possibilities!

At its most basic level, the purpose of service activation testing (SAT) is to verify that a circuit is ready for all sorts of customer traffic, meeting designed/guaranteed throughput numbers. It’s a tool to prove that service level agreements (SLAs) are being met.

Doing that proving means using one or both of the standard SAT protocols:

  • RFC-2544, which requires picking a specific packet size for each test, and uses step-increments to determine at what throughput level is tripping up a circuit if the test fails.
  • Y.1564, which is capable of testing up to 8 classes/flows simultaneously for a single circuit, and tests ‘burstability’ using CIR/EIR.

Both of these test methods are disruptive in that they require filling the circuit with test traffic, thus interfering with actual customer usage. As such, SAT is typically done during a planned maintenance window. Or, when issues arise, SAT may be performed at an inconvenient time if necessary to resolve the problem.

Given the nature of SAT, that’s just how it is… right?

The secret ingredient is ISTT

Actually, it doesn’t have to be that way. SAT can be done in a way that’s non-intrusive. The trick is to use a method that’s very granular and precise, while also being adaptable and dynamic, the same way customer traffic is. Accedian does this using what we call in-service throughput testing, or ISTT for short.

In a nutshell, what we do is inject only as much traffic as is needed to get to the guaranteed limit, on top of customer traffic—filling any gaps to test the circuit’s capacity. By way of analogy, imagine an automobile highway with traffic all driving at 75 MPH (~120 KPH). There are three lanes, but a significant amount of open spaces where vehicles could fit. Now picture being able to instantly add just enough vehicles to fill those gaps so the highway is at capacity but the speed isn’t affected. (And, if more vehicles enter the highway, imagine the ability to dynamically remove some of the extras to keep traffic speed flowing.) That’s the basic function of ISTT. SkyLIGHT monitors volume and placement of synthetic traffic (the added ‘vehicles’) to keep it at just the right level at all times.  

This allows for SAT without disrupting customer usage. For troubleshooting a circuit that’s already commissioned, or validating proposed upgrades or downgrades in capacity, this non-disruptive test ability is a huge advantage.

Performing non-disruptive service validation testing using ISTT requires the ability to measure traffic between devices at the microsecond level. Accedian is able to provide this using components of our overall solution suite.

For example, when ISTT is coupled with SkyLIGHT’s FlowMETER capability, providers can not only validate network capacity, they can also gain continuous second or sub-second utilization measurements of actual customer traffic. Capabilities like this go beyond what is traditionally thought of as SAT (validating capacity at the point of activation); this method is more accurately described as service validation testing.   

Unlike speed tests (which can’t pinpoint the location of throughput issues) or traditional SAT (which requires taking circuits out of service to troubleshoot or validate their performance), ISTT—combined with FlowMETER—extends the utility of SAT beyond troubleshooting and into the realm of preventative maintenance and proactive SLA validation. For example, if a customer’s peak utilization over time is getting close to the contracted limit, the operator could offer a promotion to add more bandwidth, or even just add bandwidth as a bonus to engender customer loyalty.

Imagine the possibilities!