The MultiService Forum (MSF) is a global association of telecom service providers, system suppliers, and equipment manufacturers, which promotes open-architecture, multiservice Next Generation Networks. The MSF aims to accelerate the deployment of open communications systems that support a full range of network services, using a variety of infrastructure technologies. The MSF provides implementation agreements to promote interoperability between components within a network and between networks.

In the fall of last year, MultiService Forum’s Global MSF Interoperability 2008 event (GMI 2008) provided the first real network multi-vendor trial of innovative new services deployed over a converged Internet Protocol (IP) Multimedia Subsystem (IMS) infrastructure. Its aim was to test standards compliance in network scenarios of interest to major Service Providers and to gauge vendor support for emerging technologies.

ATIS is a Standards Development Organization (SDO) whose mission is the rapid development and promotion of worldwide technical and operations standards for information, entertainment, and communications technologies using a pragmatic, flexible, and open approach. ATIS priorities include Home Networking, Service-Oriented Networks, Convergence and IPTV Interoperability. The ATIS IIF (IPTV Interoperability Forum) is developing specifications for industry end-to-end solution for IPTV. ATIS IIF successfully collaborated with the MSF to jointly test its emerging IPTV standards at GMI 2008. The group’s objective was to identify and correct subtle issues before its IPTV standards were finalized.

Though the testing at GMI 2008 was extensive, this article will share only IPTV-related test results.* Sharing these results provides valuable feedback based on tests carried out in real world networked scenarios that are of great interest to the Standards Development Organizations (SDO) community.

Talk About Coordination
To say this was an involved effort is an understatement to say the least. This 2-week test event involved 5 inter-networked lab sites, 22 vendors, 125+ participants, 225+ network components, and 400+ test plans, that all required careful planning. A dedicated committee of 14 people, along with numerous volunteers, spent more than 18 months preparing for the event.

Inter-lab testing was a key objective of GMI 2008. There were 5 labs that spanned the globe, with active testing of critical permutations of vendor-provided IMS cores and access tiles across all sites in a 2-week test window.

The major players in GMI included Verizon, BT and Vodafone, China Mobile,  The National Communications System (NCS), The University of New Hampshire InterOperability Laboratory (UNH-IOL), and Vendor Participants.

Verizon
Verizon provided a host site at its Walt-ham, Massachusetts, laboratory in order to advance the implementation. Other Tier 1 Service Providers provided GMI host sites in the U.S., UK, and China, thereby allowing the various tests and scenarios to be deployed in an environment that replicated a live global network. In GMI, however, there were no live customers; instead engineers made extensive use of test tools and emulation to actively monitor product performance and track, identify, and fix issues.

IPTV was particularly important, and Verizon wanted to find the additional interfaces and devices that would be required for an NGN to support IMS-based video services. Verizon also wanted to explore the architecture for and potential of SOA (Service Oriented Architecture) since it allows service providers to offer a wide range of services. SOA is an architecture paradigm that enables components from both IMS and non-IMS infrastructures to be used as part of new application and service developments.

BT and Vodafone
These two companies joined forces to provide the UK host site at BT’s Adastral Park Laboratory, Ipswich, UK. GMI’s focus on real-life deployment scenarios taking place in multiple sites around the world provided the opportunity to prove real-life roaming and nomadic scenarios that would not be possible in single lab test events. In addition, BT and Vodafone were able to demonstrate practical applicability of Fixed Mobile Convergence with two major service providers working together to prove service interoperability within a coherent IMS Core Network solution.

China Mobile
This telecom provider established a test network with other host-sites that gave them the real-life roaming and nomadic environment to gain experience of interoperability with other service providers. The most important difference between IP communication networks and the Internet is the provision of a guaranteed QoS. The end-to-end QoS test scenario was therefore of particular interest, and was considered to be the best way to validate QoS solutions within an IMS core network, especially under the demanding conditions of long-distance roaming environments.

The National Communications System (NCS)
This system is part of the Department of Homeland Security, and is the U.S. Government agency responsible for providing priority communications for Continuity of Government and Continuity of Operations during times of national and man-made disasters.

Analysis has shown that using the Public Switched Telephone Network (PSTN) to make priority calls is more cost-effective and resilient than any private government network, especially since disasters can occur anywhere in the U.S. However, during times of disaster, the PSTN may become congested when call attempts and traffic can reach 10 times the normal engineered load. It is during these times that the priority calls must be completed. NCS worked with vendors at GMI events to demonstrate the interoperability of priority communications under congestion conditions.

The University of New Hampshire InterOperability Laboratory (UNH-IOL)
As part of the network design team, the UNH-IOL saw GMI 2008 as an opportunity to expose undergraduate and graduate students to the ongoing technical advancements in the IP communications industry through practical, real-world deployment scenarios. The UNH-IOL also saw GMI 2008 as an opportunity to test today’s networking equipment with the engineers of tomorrow, and in that way help educate the next generation of industry professionals.

Vendor Participants
Twenty-two (22) companies participated in GMI 2008. The network equipment vendors were Acme Packet, Alcatel-Lucent, Fujitsu, Huawei Technologies, Motorola, NEC, Nokia-Siemens Networks, Nortel, Sonus, Starent Networks, Tekelec, TELES, and the ZTE Corporation. The test equipment vendors were Codenomicon, Empirix, Ixia, JDSU, MuDynamics, OSI, Spirent, Tektronix, and Telchemy.

Real World Issues Put to Test
The MSF partnered with the ATIS IIF for GMI 2008 to test the key IPTV protocols that will be used as the basis for scalable IPTV deployment. Without a robust architecture, service providers do not have a practical, deployable solution, but with a well-structured architecture, implementing the actual service becomes a relatively easy process with a series of clearly defined tasks. Thus, the key GMI 2008 objective in the case of IPTV was to test key protocols at the heart of the IIF IPTV architecture.

MSF and ATIS selected two key areas as the focus of their IPTV testing in GMI 2008: Network Attachment and Initialization, and Quality of Experience (QoE).

1. Network Attachment
The initial test area in Scenario 3B emulated the end user’s initial experience when purchasing an IPTV service. This architecture is based on the ‘retail model’ where the user goes to a retail outlet that sells STBs, which can be connected to any one of a number of IPTV service providers. The user purchases an STB and takes it home. Any one of a variety of mechanisms can be used to subscribe to an IPTV service and obtain an ID and password.

Once the STB is connected to the TV and the Net, the user enters the subscription information and the STB automatically connects to the appropriate service provider, and is configured for the subscribed services. Similarly, if the user moves to a new house, or simply wants to temporarily take the STB to another location, when the box is connected, it will be configured automatically. Configuration will also be automatic if the STB is replaced or if there is a hard reset caused by power failure.

The official term for this process is network attachment and initialization. The overall process of network attachment is different for IMS and non-IMS environments, but the core steps are common to both, and can be tested in a single test configuration. The test plan for GMI 2008 applied to both IMS and non IMS IPTV, based on ATIS-0800017. The data model for this test was based on Broadband
Forum TR-135 for a TR-069 enabled STB.

2. QoE
In order to ensure that an IPTV network is performing correctly, service providers must have a means of correlating Quality of Service (QoS) measurements (from test equipment) with the quality as perceived by the end user (QoE).

The QoS and QoE tests to do this were based on ATIS-0800008, which defines the metrics to be measured and how to relate these to the user experience. This allowed the various test equipment vendors to follow the same process for a given degradation and thereby find out if everybody gets the same numbers, or, if there was a difference, find out why it occurred. For example, differences can occur if there is a mistake in the way the standard was specified, or if the standard was not sufficiently detailed.

No Ambiguity = Success
The obvious objective of a standard is to enable everybody to implement key interfaces in the same way (i.e., there should be no ambiguity). Information from these tests has been fed back to ATIS IIF Quality of Metrics Committee and if necessary there will be a revised version of the standard. Specifying a standard is one thing, but the various tests that they embrace must be useful, so GMI 2008 allowed the vendors to provide feedback as to whether they provided a useful metric or not.

In the field, it is hard to overstate the importance of QoE. Subscribers will not accept an IPTV experience that is inferior to that of regular broadcast services; in fact, they will have chosen IPTV because they expected something better. Thus, QoE and network attachment/initialization are, from the subscribers’ perspective, two of the most-important issues.

Remote STB Management/Performance Management
A large part of the QoE in mass deployments has to do with the STB. In order to standardize quality and make IPTV scalable, the area of remote STB management is critical. Specifics surrounding the management of the STB include configuration, remote diagnostics, and performance management.

Configuration takes place when the service is accessed for the first time and in an ideal world every¬thing works faultlessly. When it does not, or when there is a subsequent problem, remote diagnostics are employed to troubleshoot and address the issue. The ability to remotely manage the STB is criti¬cally important for the reasons outlined earlier (i.e., service providers cannot afford truck rolls).

Performance management is equally important since the business case for IPTV would start to break down if subscribers did not get the expected QoE. This test allowed the service provider to monitor the QoS and QoE parameters and to take action before subscribers start to complain. It is also used to track the services that are being used.

These three use cases are a subset of the TR-135 data model. The test cases were designed to validate the interoperability between the Remote Management Sys¬tem/Auto Configuration Server (ACS) and the STB through the successful collection and reporting of specific parameters, and to validate the ACS's ability to issue commands to the STB. This allowed the test cases to validate the protocols specified in TR-069 and the data model specified in TR-135.

Officially, this GMI 2008 test was designated as Scenario 3b. It covered the authentication and initialization of CPE and validation of QOS metrics as outlined in ATIS specifications. The objectives were as follows:

1. Validate the network attachment and initialization standards as specified in ATIS-0800017.

2. Validate the mechanisms for relating QoS to QoE as specified in ATIS-0800008, which defines the metrics to be measured and how to relate these to the user experience.

3. Test STB management in three key areas:

A. Configuration: initial configuration of a STB and collection of baseline information.

B. Remote Diagnostics: including both the fault management and trouble management aspects of TR-135.

C. Performance Management: monitoring of STB performance, such as QoS parameters, QoE param¬eters, and usage statistics.

Learning for the Future
When the testing was complete, MFS revealed the following observations from Scenario 3b: the testing provided an effective proof of concept test for the basic registration and initialization mechanisms defined by IIF.

- The correlation of metrics for QoS with the QoE as experienced by the end user was effectively tested.

- ATIS-0800017 stipulates three options for ACS device discovery, involving mechanisms by which the DHCP server informs the ACS of service provider information. With the industry moving toward the adoption of TR-069 enabled devices for remote STB management, this poses a fundamental issue in that TR-069 enabled devices require a full URL to issue an INFORM. Options 1 and 2 do not provide sufficient information for a TR-069 device to construct the ACS URL without having additional infor¬mation. The likely result to emerge in the IIF specification is the mechanism by which the DHCP Server provides the full URL of the ACS in DHCP Option 43.

- Testing of ATIS 0800017 IPTV also yielded some crucial information on service provider provisioning on a device. The specification stipulates that for a TR-069 device, a single string parameter should be populated with an instance of the XML schema defined in IIF-WT-028R9_CDDC_Metadata for IPTV service providers. This is not a tractable solution for TR-069 devices because the string would need to be entirely encoded to prevent parsing errors. It also diverges substantially from standard TR-069 mechanisms.

What does this mean in translation? It means four things to service providers aiming to mass deploy IPTV:

1. IMS protocols are generally mature, and IMS products interoperate across Service Provider environ¬ments.

2. IMS products employing QoS enable an end-user experience that is superior to best effort Internet services.

3. IMS demonstrated the ability to provide a platform for convergence of a wide range of innovative services such as IPTV.

4. Though the IMS standards are mostly mature, the overall architecture is complex and the choice of implementation significantly impacts interoperability.

During the event it was observed that most of the defined interfaces were mature and interoperable, however configuration issues needed to be resolved. Calls were successfully established across all access technologies and between most combination pairs. Roaming was also successfully tested for most relevant access types. Although essential standards are reasonably mature, the overall architec¬ture is very complex, and requires significant choices to be made in local configurations. Events like GMI highlight these difficulties and prove the validity of the MSF approach to developing Implementa¬tion Agreements (IAs) as an aid to achieving multi-service interoperability.

For the industry at large, this test series offered expeditious feedback to and from the SDO's and the MSF. Because ATIS jointly developed GMI 2008 IPTV test plans with the MSF, this first-hand experience was immediately fed back into the ATIS IIF standards group. This approach significantly shortened the typical feedback cycle between MSF and the Standards Development Organizations (SDO) community. The proof of GMI's 2008 event success was evidenced by that feedback time being cut in half – from about 12 months down to 6.

Endnotes: A number of ATIS deliverables for IPTV have already been published. They include: IPTV architecture requirements and an IPTV roadmap; a framework for QoS metrics and measurements supporting IPTV services; IPTV packet loss and the remote management of devices. In addition, 19 standards and specifications are under development in 5 technical committees that deal with an overarching reference architecture, security solutions, metadata and transaction deliver, quality of service metrics, and testing and interoperability. The standards are quickly maturing, and ATIS concluded that it was important to test these standards as soon as possible to ensure they met service provider requirements in a live network environment.

*Consult the white paper GMI 2008: Application and Service testing in global Next Generation Network available for review at http://www.msforum.org/interoperability/02-MGS81044-MFS_Whitepaper.pdf. 

About the Author
Roger Ward has more than 30 years of experience in senior positions in the telecommunications industry, and is President of the MSF. The MSF is a global association with a membership drawn from the world’s leading IP communications companies. The MSF promotes the testing of interoperability based on open standards. For more information, visit www.msforum.org.

GMI 2008 is the fourth in a series of biannual events designed to test standards compliance in network scenarios of interest to major Service Providers. GMI 2008 provided the first real network multi-vendor trial of innovative new services deployed over a converged IP Multimedia Subsystem (IMS) infrastructure.

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