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The MultiService Forum (MSF) closed in March 2013. Founded in 1998, the MSF had an extremely productive 15-year run. The MSF leaves behind a legacy of Implementation Agreements, Physical Scenarios, Testing Scenarios, Test Plans, Architecture Frameworks and White Papers developed to support its interoperability program. To maximize the ongoing value to the industry, all of these approved MSF documents will continue to be publicly available on the MSF website, for unrestricted use, until March 2018.

MSF: Interoperability Forum Folds, Leaves Impact on Industry

Introduction
The maturity of today's multiservice network architecture owes a lot to initiatives like the MultiService Forum (MSF) Global MSF Interoperability (GMI) events over the past decade. These events, in partnership with GSMA, ETSI and ATIS, provided an effective vehicle for bringing together service providers and equipment suppliers to conduct proof of concept testing for emerging technologies. The MSF didn't initially conduct interoperability testing, but it quickly emerged as the unifying theme for everything the forum did. Here we review how the focus on interoperability emerged, the factors that contributed to the success of the interoperability program, and the reasons the MSF has deciding to close at this time.

MSF's Formative Years
The year was 1998, and the technology world was at war; Bellheads vs. Netheads. The Netheads believed the Internet had changed everything, and the old rules no longer applied. Bellheads believed IP could never deliver the quality and reliability that users demanded. It was before that great equalizer reality - proved them both wrong. Before the Internet bubble burst. Before Broadband Internet was the norm. The MSF began in a world very different from the one we know today.

The inaugural meeting of the MSF in December 1998 brought together key service providers, system suppliers and test equipment vendors committed to developing and promoting open-architecture, multiservice Next Generation Networks. This commitment shaped the MSF:
  • Open-architecture encourages innovation, but complicates interoperability. Rigorous testing ensures the standards are accurate and complete.
  • Multiservice networks offer flexibility, but that very flexibility complicates testing unless a realistic network configuration is provided.
  • Next Generation Networks introduce a new architecture that must be tested as an end-to-end network.
Viewed through this lens, the MSF focus on interoperability testing isn't surprising.

Global MSF Interoperability (GMI)
In 2000, the market collapsed, and greed changed to fear. Next generation network architectures were complex and unproven. Interoperability testing was expensive, and repeating the tests in every carrier lab compounded the problem. This insight was the impetus for the first Global MSF Interoperability (GMI) event, with equipment in Europe, North America and Asia networked to form a single, global interoperability test bed. Three carriers - BT, NTT and Qwest along with a dozen equipment vendors participated in the first event. GMI provided a valuable "proof of concept" test for critical interface standards and demonstrated the maturity of the next generation network architecture. GMI testing didn't replace detailed "plugfest" testing focussed on a single interface. It didn't replace vendor regression testing or carrier acceptance testing. Instead, GMI played a complementary role by validating the architecture and the standards.

The MSF held four GMI events from 2002 to 2008, introducing additional functionality with each event:
  • GMI 2002 validated the H.248 Media Gateway Controller protocol, decoupling service logic from the media gateway;
  • GMI 2004 added SIP trunking between H.248 based softswitches and saw KT join the list of participating carriers;
  • GMI 2006 introduced IMS, and included equipment in BT, KT, NTT, and Verizon labs; and
  • GMI 2008 added IMS services and saw participation by BT, China Mobile, National Communications System (NCS), the University of New Hampshire Interoperability Lab, Verizon and Vodafone, along with 22 network and test equipment vendors. For the first time ever, the MSF also partnered with another standards organization, validating key IPTV standards developed by ATIS.

The Post-GMI Years
The original mission, validating open-architecture, multiservice, Next Generation Networks, had been achieved, but the MSF membership proposed smaller-scale interoperability testing in two additional areas; LTE and IP Interconnection.

LTE: Standards for LTE include a new data architecture; the Enhanced Packet Core (EPC). The MSF conducted three LTE/EPC interoperability tests (IOT), with each event expanding the scope of testing.
  • LTE/EPC IOT (2010) focused on core components in the LTE/EPC network.
  • LTE VoLTE IOT (2011) introduced a key service, Voice over LTE (VoLTE), and validated key GSMA specifications for VoLTE in a joint MSF/GSMA event.
  • RCS/VoLTE IOT (2012), conducted jointly with GSMA and ETSI, introduced Rich Communication Services (RCS) to validate a complete LTE service scenario.
  • Taken together, these three IOT events provided a complete proof of concept test for LTE/EPC, VoLTE and RCS services.

IP Interconnect: A significant portion of traffic between networks is still based on legacy TDM interfaces at the Network-Network Interface (NNI). IP interconnection exists, but is still complex. The MSF launched a series of test events to validate the enabling IP interconnect standards.

  • P-IOT (2010) focussed on performance monitoring and reporting at the IP NNI.
  • ETS-NNI IOT (2013) validated standards for Emergency Telecommunications Service (ETS) across an IP-NNI.

Success Factors
The success of the MSF interoperability program was driven by several factors.

  • Carrier driven: MSF interoperability events were built around major carrier procurement programs and held primarily in carrier labs. Vendors gained visibility with potential customers, and carriers assessed overall product maturity. It was a formula that drove both carrier and vendor interest in GMI.
  • Realistic Network Testing: The MSF was unique in assembling complete networks for interoperability events, enabling proof of concept testing for next generation network architectures.
  • Testing the Standards: GMI events tested the standards, as much as the products, sometimes uncovering errors or ambiguities in the underlying specifications. Improving the standards made a lasting contribution to the industry.
  • Cooperation: The MSF sought to cooperate with other forums rather than compete.

Dissolution
In February the MSF membership voted to dissolve the forum. Why make this decision immediately following another successful interoperability event? It had a lot to do with the MSF mission and mindset. The MSF focussed on gaps not addressed by other forums, for example, developing Implementation Agreements (IA) to improve interoperability by narrowing options and resolving ambiguities in existing standards. As interoperable standards matured, the need for IAs decreased and eventually disappeared. Similarly, the maturity of multiservice networks is removing the need for further large scale, global interoperability events. Interoperability testing will increasingly focus on specific markets or standards.

Conclusion
The MSF brought together key service providers, system suppliers and test equipment vendors committed to developing and promoting open-architecture, multiservice Next Generation Networks. The MSF's work contributed to the maturity of multiservice network architectures, which changed the nature of interoperability testing. Recognizing this change, the MSF opted to close the forum. The MSF leaves a legacy of interoperability scenarios, test configurations, test plans and event results that will be released for unrestricted use. All MSF technical documents can be found here.