March 2002

Dependable Network Monitoring

BY RAVI RAVISHANKAR

The emergence of packet telephony and the growth in the number of wireless subscribers has triggered fundamental changes in the way operators manage network infrastructures. The rapid growth of wireless subscribers, combined with new service delivery mechanisms such as prepaid services, requires that operators manage network expansion in near real-time. In addition, the increasing competition and pressure to improve profit margins compels operators to take proactive steps to protect revenue by preventing fraud and reducing customer churn while enhancing customer satisfaction. To remain competitive, carriers need the ability to monitor the status of the network in real time as well as an effective means of collecting, aggregating, and analyzing the network control information. And at the same time, they have to protect the privacy needs of subscribers.

The convergence of packet and voice networks poses additional challenges to the operator. In developing the new services and products, carriers are melding voice and packet technologies to deliver actual converged services. The result is a new network architecture that blends legacy and emerging technologies.

This new scenario calls for providers to change perceptions and concepts of how to manage networks. In the traditional network, most of the information was collected at the switches, and often operators depended on subscriber complaints as a primary source of information. In the new network architecture, the status and control information has to be collected at multiple networks, in multiple formats, and then correlated. So, the task of information monitoring, collection, and aggregation becomes even more challenging. To minimize the impact of new architectures and services and to manage the growth of the network, operators need advanced network monitoring and maintenance systems that provide real-time information; a platform for troubleshooting; and an information �feed� for business applications.

Internet Protocol Signaling Challenges
Operators often are blind to the transport of messages over IP in converged networks. A lack of equipment to manage high-level telecommunications signaling over IP networks hinders the ability of the operator to effectively manage their networks. In a converged network, operators often are unable to detect problems in the services provided by IP-based transport protocols and correlate them with legacy protocols. For example, to effectively manage a voice over IP (VoIP) network, tools are needed to simultaneously monitor and correlate a large number of protocols and devices such as the following:

• Signaling transport layer protocols such as M2UA [message transfer part (MTP) 2 user adaptation layer]; M3UA [MTP 3 user adaptation layer]; stream control transmission protocol (SCTP); and transport adaptor layer interface (TALI);
• Media device transport protocols such as real-time transport protocol (RTP);
• IP device control protocols such as media gateway control part (MGCP) and media gateway control protocol (MEGACO);
• VoIP network control protocols such as session initiation protocol (SIP), H.323, and session description protocol (SDP);
• Public switched telephone network (PSTN) signaling protocols such as SS7 message transfer part (MTP), SCTP, integrated services digital network user part (ISUP), mobile application part (MAP), and advanced intelligent network (AIN);
• Status of signaling links, transmission control protocol (TCP) sockets, and so forth;
• Interworking between SS7-based and IP-based signaling; and  
• Gathering and consolidating traffic statistical data across SS7- and IP-based networks.

Telecom service providers are challenged by the many different protocols at work in their networks. They have been forced to use different monitoring solutions for different networks and, in some cases, sacrifice the monitoring of parts of the network. As a result, without a monitoring system for the IP links or for times when two monitoring systems are employed, an operator does not have a consolidated view of the calls crossing the network. For example, an SS7 monitoring system shows the portions of the call transported via SS7, and another system captures the messages transported over IP. When troubleshooting a problem, a carrier is not able to perform a call trace that captures the entire call. A mechanism to allow operators to visually trace a call that traverses multiple protocols within a single view is needed.

The Solution
The best way to ease the burdens faced by telcos is to provide a single monitoring system for the entirety of the converged network. Such a solution enables wireline and wireless service providers to monitor, maintain, and ensure the reliability of innovative telecommunication products and services implemented across SS7-based PSTNs and next-generation, packet-based wireline and wireless networks.

Operators use the monitoring device to correct network-wide problems from a central location and monitor and trace calls end-to-end. It enables a number of applications, including those deployed for fraud detection, mass call detection, billing verification, and quality of service measurements.

Another critical feature for the next-generation monitoring solution is probeless monitoring. Current generation monitoring equipment requires probing the network at hundreds of points, which is expensive, not scalable, inflexible, and cumbersome. Instead, the next-generation signaling network will have the intelligence to self-monitor and feed useful and appropriate information to various business systems for fraud control, customer service, and network planning. Signaling transport networks, which provide the point of convergence for all control information, become an excellent source for monitoring and collecting useful information.

Looking Forward
Future network operator developments include the incorporation of additional IP protocols, including SCTP, M2UA, M3UA, MGCP, and SIP into networks. Business applications, such as fraud detection, billing verification, and quality of service (QoS) are expanding to incorporate data derived from emerging technologies and protocols.

Network monitoring and data mining must be treated as part of the next-generation signaling network design; it must not be viewed as an after-thought.

Via the deployment of a network monitoring system that provides a consolidated view of a converged network, operators are armed with the information they need
to proactively manage their networks, services, and customer bases. c

Mr. Ravi Ravishankar is director, Advanced Technology Planning, Tekelec. His focus is on defining signaling solutions and products for the next-generation packet telephony and 3G wireless networks. Tekelec is a leading developer of telecommunications signaling infrastructure, softswitches, testing and diagnostic solutions, and service applications. Please visit their Web site at www.tekelec.com.

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