0. reliability of ims architecture

0. reliability of ims architecture - 2007 Australasian...

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Reliability of IMS Architecture Veena B. Mendiratta Bell Labs Alcatel-Lucent Naperville, IL 60566, USA veena@alcatel-lucent.com Himanshu Pant Bell Labs Alcatel-Lucent Murray Hill, NJ 07974, USA hpant@alcatel-lucent.com Abstract — The IP Multimedia Subsystem (IMS) enables an access-agnostic Next Generation Network (NGN) that integrates wireless, wireline and internet technologies. IMS provides for real-time voice and data services over a packet-switched domain via a Session Initiation Protocol (SIP) infrastructure. It also offers a cost-effective platform for the creation and deployment of IP-based multimedia services. Given the wide scope of services that can be offered with IMS it is important to develop a framework to analyze the reliability of these services. Using an IMS reference architecture, this paper presents a network level failover analysis using the IMS architecture capabilities and shows its impact on improving service reliability. We show how to analyze the end-to-end service reliability in terms of detection and recovery mechanisms and redundancy. Keywords – IP Multimedia Subsystem; Next Generation Network; Reliability I. INTRODUCTION Achieving high reliability in Next Generation Networks (NGNs) such as the IP Multimedia Subsystem (IMS) [1], equivalent to that in more traditional circuit-based networks, is challenging because of the complex and distributed nature of such networks. Some example drivers of IMS reliability challenges include the following. Network/service availability is complex because there are many different network elements and service functions. Each IMS-supported application and service can have unique reliability, performance and QoS aspects; for example, call by call, instant on virtual connections, always on, and can be session, packet or call based. Reliability metrics may differ by service and the requirements may be undefined or not universally accepted. IMS network functions are more disaggregated than in traditional circuit or packet networks; for example, many more types of network elements are involved in setting up a call or session. For a given number of subscribers there are likely to be fewer numbers of switches and service nodes of any type in IMS networks than in traditional networks thereby making the impact of a switch or service node failure more widespread. As an example, in the PSTN network if there is a failure of the local exchange switch the impact is confined to a relatively small geographic area – the subscribers on the failed switch. On the other hand, if there is a failure of a softswitch or an application server the impact is likely to be more widespread and impact many more subscribers. The IMS layer overlays multiple other layers and relies on their reliability. Given these challenges, it is important to have analysis methods for risk assessment that can determine when to release and deploy the system.
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This note was uploaded on 09/21/2010 for the course ECE 567 taught by Professor Attkin during the Spring '10 term at Academy of Design Tampa.

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0. reliability of ims architecture - 2007 Australasian...

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