Interoperability and Other Testing in IMS

By Richard "Zippy" Grigonis
For quite a while now we’ve followed the Plugfests of the IMS Forum (now called the IMS/NGN Forum) all of which facilitate industry-wide certifications of IMS applications and services interoperability. These Plugfests have generally been held at the University of New Hampshire InterOperability Lab (UNH-IOL ). The Forum has the good fortune of hosting testing companies as well as vendors at its events at the UNH-IOL. Indeed, at the very first Plugfest in January 2007, Tektronix’ then-new IMS interoperability test suite was used to evaluate vendors’ IMS implementations.

The Tektronix IMS Interoperability Test Suite consists of more than 100 selected test cases, prepared in cooperation with Europe’s largest open IMS test laboratory, the Fraunhofer-FOCUS IMS Playground and with IMS test centers of large network equipment makers worldwide. The test cases are formulated to place stress on complex procedures that are likely to cause interoperability problems. The abstract test suite implementation is in TTCN-3, the global open standard for test case definition. Using a suite of test cases allows for a high degree of test automation, boosting the efficiency of IMS device and system test campaigns, significantly reducing test time (time-to-market) and test cost.

The Tektronix IMS Test Suite is executed inside the Tektronix TT-Workbench application, a TTCN-3 execution and editing environment for the Tektronix K1297 G20 and G35 series of protocol test systems. All test traffic is captured and decoded through the G20/G35 analysis software, allowing for rapid root cause isolation of failed test scenarios. Tektronix also offers the Spectra2 and Spectra2XL test platforms for VoIP, IMS and converged networks, which does functional and load testing in a single box.

tekVizion Labs also offers IMS Conformance/Interoperability Testing. They can verify products designed for IMS networks including testing to the IMS specifications, testing interoperability among IMS components and certification of third-party applications into trusted IMS networks. For example, tekVizion Labs can provide ISC Interface Certification to certify the interoperability of a specific applications server-to-SCIMs/S-CSCFs, SCIMs-to-S-CSCFs, and so forth.

Out-of-the-Box Compatibility?

At Empirix, one of the most respected names in the testing hardware and software business, Chad Hart , Product Marketing Manager, says, “Interoperability is still a challenge. It’s come along way but it still has a ways to go. As a result of my conversations with network operators who are actually deploying IMS, most of them are choosing to go with a single vendor as opposed to many. It’s not the best time for achieving interoperability, but it’s good for IMS in that operators are actually to deploying it. Interoperability is one of the bigger challenges faced by IMS adoption. The way the IMS/NGN Plugfests are set up, they are usually done in stages. The first stage is just establishing a basic call or doing a basic registration between different vendors, which is what practically the whole first Plugfest was about. At the most recent Plugfest, vendors achieved the first step very quickly. It’s a sign of real progress for interoperability. How quickly can vendors’ equipment actually work together practically right out of the box?”

“Are operators now so comfortable with multivendor operability that they’re willing to make deployments in their live networks?” asks Hart. “I don’t think that’s true on a large scale yet. Certainly some of the larger operators have pretty sophisticated interoperability labs where they’re demonstrating multivendor interoperability internally, but they haven’t deployed to the networks yet, though of course they have plans to do so. Another trend is that many vendors are aware of the interoperability issues and have partnered with some of the best-of-breed component vendors out there to make sure they can interoperate with at least specific vendors or devices.”

“There are of course economic considerations,” says Hart. “While is might be theoretically possible to mix-and-match all of these various IMS functions from different vendors, that doesn’t necessarily imply that such a practice is economically viable. If you buy a lot of equipment from one vendor, they’re going to give you a better price than if you just buy one component from one vendor and one from another vendor. The reality is that interoperability is probably going to be done in ‘layers’. Certainly there are many different kinds of application servers out there, along with many different services. One main goal appears to be have pretty broad interoperability with the service layer. Similarly, there’s a lot of different kinds of network edge access equipment.

To read this article in its entirety online, visit the TMC website at www.tmcnet.com/2089.1

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