Andy Huckridge

Overcoming Deployment Limitations of IMS

by Andy Huckridge, M.Sc. (Telecoms)

Director of Marketing, IMS Solutions

8/22/06

There’s little doubt that the future of IMS (IP Multimedia Subsystem) is bright. According to ABI Research, the IMS services market revenue is expected to be somewhere between $50 billion to $90 billion by 2010. There are dozens of IMS trials underway around the world and it is difficult to attend a telecom conference or seminar without IMS being discussed. 

IMS is expected to play a key role in the convergence of telecom services and offers the opportunity for revenue growth by attracting new customers and increasing the average revenue per user. The IMS architecture, based on IP, allows for the delivery of services to subscribers independent of device or network type – regardless of location. It can be used to provision true mobility with services that will follow the user from a computer, mobile device or even television through a single account.

While this convergence will facilitate easier access to services and a variety of revenue generating applications, it will also open the door to potential complaints from customers about networks failing, poor media, and less-than-satisfactory performance.

IMS is a continually evolving series of protocols and interface specifications designed to facilitate standards-based fixed/mobile, voice/data and voice/video convergence. With dozens of specifications — not all of which are standards-based, or set to become standards any time soon — these protocols may create some ambiguity in the development and implementation of communications services. However, this has done little to dampen the industry’s collective spirit. Network convergence presents an unprecedented opportunity for a new wave of network and handset upgrade cycles.

The transition to a full-IP network will be characterized by a series of intermediate steps over the course of several years as equipment manufacturers work to meet the technical and business challenges that their customers — the service providers — must tackle. This complex process will likely be best addressed through partnering and consolidation.

Curbing IMS Complexity 

The inherent complexity of IMS — and its numerous standards, interfaces and protocols — may present a stumbling block for many. Implementing IMS is far from simple. Prototyping and predicting how such traffic impacts a network will be difficult to initially manage.

Complex interoperability requirements such as handshaking, media conversion and synchronization must be resolved in order to guarantee quality of service. These issues underscore the need for a deep understanding of underlying technologies as well as the importance of interoperability testing, feature testing, performance and scalability assessment, and Quality of Experience (QoE) and service management. Each of these phases of testing will play a critical role in the successful deployment of IMS-based networks.

Ensuring Success through Multi-Level Testing

While network equipment manufacturers begin to create Network Elements to handle IMS protocols, service providers must be certain these systems are configured properly and provide consistent, integrated services. This process will include testing equipment to ensure functional, interoperability, scalability, security and fault tolerance. The uncertainty associated with IMS specifications will likely impact the amount of system testing and tuning required during early trials and on-going service management. Routers/switches, gateways, session border controllers, softswitches and DSLAMs, PBXs and endpoints will have to support a variety of protocols. Understanding the types of service that a network may handle will help to determine potential issues and what could impact the delivery of service.

Simply testing the operation of IMS infrastructure is not enough. QoE must also be examined to understand that multimedia applications including voice and video are meeting customer demands. Testing should also continue into the initial phase of an IMS implementation so that service providers can assess any issues from the field to guarantee that data has been correctly formatted and is delivered to the simulated end point.

Essential for proper simulation, emulation and testing is the use of equipment that understands the session state. Simply testing individual message packets to review standards compliance is a recipe for failure in an IMS environment. The complex handshaking and session management requirements of implementing a real-world IMS network demand that such sessions, bridging multiple networks, must be simulated. This must occur with realistic appraisals of performance in session setup, operation and teardown as well as performing the correction actions when something goes wrong.

Traffic simulation, equipment and device emulation, and other tests are required to understand that the IMS network and associated infrastructure can accommodate this type of traffic. Testing and stressing of different formats of SIP headers, handshakes across wireless and wireline networks, and circuit-switched and packet-switched networks, will be the first stage in testing. This will ensure that handshakes occur properly; errors, drops and retries are responded to in a timely manner using agreed-upon parameters, and that call accounting, authorization and access controls meet required policies.

Integration testing is another key step in this process. It must not only be performed in test environments but in operational networks as part of validating the work of partners and testing the deployment of new services.

Given the rate at which new IMS protocols are introduced and revisions are made to existing protocols, regression testing is critical. Regression testing enables network equipment manufacturers and service providers to ensure that the IMS platform being deployed will be able to transit new/revised protocols through the operational network. Regression testing ensures that new and/or revised protocols do not introduce new problems into the network.

The Untested Potential 

The IP Multimedia Subsystem is poised for tremendous growth–and the rewards will affect the entire telecommunications industry. Service providers and carriers will create compelling new services for their consumer and business customers based on fixed/mobile convergence, device-independent mobility, the delivery of advanced VoIP and video services, Internet integration, Cellular Push-to-Talk, and more.

However, the ability to successfully deploy IMS and maintain a high QoE is clearly dependent on rigorous testing of all IMS Network Elements and of the network infrastructure itself. Because of the complexity associated with IMS, service providers will face an entirely new set of challenges in the network management arena. The right testing during deployment as well as ongoing monitoring and service management can support an IMS network and applications that lead to increased revenue and subscriber loyalty.

About the Author

Andy Huckridge is director, IMS Solutions Marketing at Spirent Communications, where he leads Spirent’s IMS strategy for the VoIP market. His responsibilities include business planning & market development.Andy has worked in the communications industry for 12 years including roles at Centile, Inc., and 8×8, Inc., where he was director of product marketing, and has a broad background in defining and marketing products in the Semiconductor and IP Telephony space.He holds a bachelor’s and master’s degrees in Telecommunication Engineering from the University of Surrey, England. Andy is active in various Forums including the Multi-Service Forum, where he is Chairperson of the Interoperability Working Group.

About Spirent Communications

Spirent Communications  is a global provider of integrated performance analysis and service assurance systems that enable the development and deployment of next-generation networking technology such as Internet Telephony, broadband services, 3G wireless, global navigation satellite systems, and network security equipment. Spirent’s solutions are used by more than 1,500 customers in 30 countries, including the world’s largest equipment manufacturers, service providers, enterprises and governments.