Full-Service Operation and IMS Network Management

1 Background of IMS in Full-Service Operation
All three Chinese telecom operators have obtained qualifications for full-service operation. Therefore, they need to carefully consider the technologies used to implement full-service operations, and the appropriate solutions for improving their weaknesses.

    Prior to 2009, Chinese operators such as China Telecom and China Mobile invited many IP Multimedia Subsystem (IMS) vendors to test and validate the basic functions of IMS. An all-IP-based IMS network makes full use of multiple access modes of mobile and fixed line networks. It can also provide new services, which are attractive to operators. Since 2009, in the era of full-service operation, original mobile and fixed network operators have incorporated the construction of IMS networks into their development plans.

    With the trend towards mobile and fixed convergence, equipment vendors in the field of network management have begun to consider the implementation of unified network management to meet market demands for easier operation, maintenance and management.

    It has become necessary to devise a management concept for the IMS network in the full-service operation mode, and to construct a management network that meets the requirements of telecommunication operation. Only after the sticking points of IMS network management are removed, can successful large-scale network construction be achieved.

    In this paper, IMS serves as one of the approaches to full-service operation. Management of full-service IMS networks is also discussed from multiple angles to provide insight into management of large scale network construction[1-4].

2 IMS Networks Require Unified NE Management
Telecom equipment management suppliers provide Operation and Maintenance Centers (OMC) according to the network type and NE type.Although it is simple for equipment vendors to configure network management according to NE types, operators have to set multiple OMC Network Management Systems (NMS) for only one network. This not only increases operators’ hardware investment in network management servers and client-end PCs, but also requires more device space and heavier workload on operation and maintenance personnel. In addition, the management interfaces of OMCs differ from each other, which increases training costs for users and leads to complaints from O&M personnel. Therefore, operators seek to reduce the number of network management servers. Devices from the same supplier should be managed by one central OMC to lower investment and maintenance costs. For terminals and access devices, the management modes, device features, and required quantity are different from that of the core control layer. Therefore, operators with large-scale commercial networks usually set an independent OMC for the management of terminals and access devices.

    The architecture of OMC/Element Management Systems (EMS) in IMS is shown in Figure 1. The Element Management Layers (EML) of NEs in different areas are managed by different OMCs/EMSs. In the IMS network, the unified OMC/EMS is maintained by the same maintenance personnel. This overcomes the isolation of NEs in different areas. For a unified OMC/EMS, the following features are required:

    (1) The interface style must be uniform, and different NEs should use the same management style in the IMS NMS. The uniformity of the interface style lowers the cost of training personnel in IMS operation and maintenance, and can improve operational efficiency.

    (2) The IMS network is an organic whole. Tracing and managing network quality and alarms is necessary, and unified reporting is a must for IMS network management.

    (3) The IMS network accesses the upper-level Business Operations Support System (BOSS) system as a whole network. The unified northbound interface reduces the work load of the interconnection and thus decreases the possibility of failure.

    In short, the IMS NMS should enhance report management, northbound interface and unification of interface styles, as well as providing traditional functions such as performance management, alarm management, configuration management and security management.

3 End-to-End Application is a Precondition for Large-Scale Commercial IMS
The all-IP architecture of IMS brings about a flat network, intensive function division, and an increase in NE types. Delivery of one subscriber service requires passing through many NEs. Moreover, it may be necessary to pass through one NE many times for one service, creating a Session Initiation Protocol (SIP) link. In addition, there are many types of IMS services, and service logic is complicated and highly associated. Management and interconnection also require intensive effort.

    The features of an IMS network make it difficult to locate service faults. The quality of end-to-end service is a precondition of telecommunication services. The area-based quality assurance method for traditional networks is not applicable to all-IP IMS with simple but varying NEs.

    Therefore, when NE management is unified, a prerequisite for large-scale commercial IMS in full-service operation is to ensure end-to-end service quality by developing end-to-end applications and tools.

    For example, when the quality of user call is poor, corresponding media analysis and quality tools must be provided for analyzing Real-Time Transport Protocol (RTP) communications for voice or video. This involves the automatic analysis of the process and details of the expected call. When the subscriber service fails, automatic cross-NE signaling analysis is required to trace the service processing, locate the fault, and determine the reason.
Therefore, the introduction of an IMS network significantly impacts the traditional telecommunications management system, and thus the development of end-to-end application analysis tools is necessary.

4 Security of IMS NMS
NMS security should be enhanced in an all-IP based network. In the IMS domain, the implementation of NMS security involves networking, operating system, database, OMC and anti-virus.

    The following measures should be adopted to accomplish the desired security:

    (1) A single network management domain should be implemented in the IMS domain.

    (2) An independent Virtual Local Area Network (VLAN) should be established for network management.

    (3) The outband networking mode should be used.

    (4) The network management domain and devices should be physically isolated in the outband networking mode by setting a hardware firewall between networks.

    (5) The Unix operating system should be used and regularly updated.

    (6) The minimum system configuration should be customized to restrict the breaches of system security.

    (7) Security patches for the OMC database should be obtained and user rights should be controlled to lower the possibility of security risks.

    The multiple-OMC system should use encrypted protocol such as Secure Shell (SSH) or Secure File Transfer Protocol (SFTP) to transmit data. Sensitive data, such as username and password, should be encrypted before storage. Forcible password authentication is used. Both the working time and the hierarchical user rights are set, and the management scope is also defined according to the rights division and domain division.

5 IMS Accelerates Integration of eTOM and ITIL
The Information Technology Infrastructure Library (ITIL) was developed by the British Department of Commerce. It defines a framework for delivering best practice, high quality IT services. It is service orientated, and helps decision makers invest in specific parts of the IT infrastructure to maximize their yield on investment.

 
    With service management as its core, and service strategy as its guide, ITIL creates a process framework that incorporates service design, conversion and operation. The introduction of “lifecycle” and continuous improvement of services results in best practice.

    The Telecommunications Forum has put forward proposals that would construct a bridge between the enhanced Telecom Operations Map (eTOM) and ITIL, proposing a trend towards integration. IMS development is accelerating the integration of eTOM in the telecom field and ITIL in the IT field. Existing functions in the eTOM will become elements in the construction of the integration process. These functions offer service for the final business flow, and provide unified and standard services for end users.

    With the introduction of IMS, telecommunication hardware, including control-plane and service NEs but not gateways interconnected with traditional telecommunication systems, can use Advanced Telecommunications Computing Architecture (ATCA)-based blade servers or universal servers to implement their functions. The situation is changed whereby traditional telecommunications systems use a closed hardware platform for each supplier. The hardware devices approach current open platform IT devices. This accelerates the integration of the two concepts.

    Operators have changed from being device-oriented to service-oriented and customer-oriented services. Currently, one operator provides hundred of types of services for end users. However, it is difficult for operators to manage, select and promote services. ITIL is constructed with the core concept of service. Operators and IT service providers are becoming more alike in their service concepts. This may eventually lead to the integration of eTOM and ITIL.

    In the evolution process, integration and mutual complementation are progressive. eTOM establishes the commercial process framework for the entire telecommunication industry and also the global requirements. ITIL, on the other hand, provides a detailed service-oriented framework.

    ITIL provides the methodology and process framework for IT service management. However, the actual telecommunication service processes should be analyzed and designed in detail. These designs will require the adjustment of operators’ BOSS business flow to adapt to the service-oriented concept.

6 Conclusions
IMS applied in full-service operation is a new business. It poses a challenge to traditional network operation and management. More efforts are required to adapt the development of new network concepts for traditional operators and equipment vendors. It is clear that an all-IP based IMS network would be used for full-service operation.

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[Abstract] IP Multimedia Subsystems (IMS) is considered as a comprehensive approach for full-service operation. However, traditional network management concepts are not applicable to IMS network management. This is because IMS is characterized by a flat, all-IP architecture, simplified functionality of Network Elements (NE), and a variety of NEs. This paper introduces an IMS network management system design that covers full-service operation. It then discusses the significant role IMS network management plays in the unification of NE management layers, the increasing importance of end-to-end applications, and the convergence of Enhanced Telecom Operation Map (eTOM) and IT Infrastructure Library (ITIL).