Network Convergence

Published on 18 March 2010 by in Networks


As Ethernet technologies have evolved and increased in bandwidth, the generally low cost solution has eclipsed higher cost network technologies. Many enterprises are implementing converged networks that utilize common cabling and switching technologies to replace the diverse solutions previously used. For example, many companies operate voice over Internet protocol (VoIP) phones in place of traditionally cabled telephony equipment.

Operating converged networks presents unique technological challenges. Emergency services, like 911, depend upon location information that is provided by the public switched telephone network (PSTN). Voice over Internet protocol (VoIP) telephone technology enables convergence of data and voice networks, but jeopardizes the location capabilities formerly provided by the PSTN. (Jeong, Lee, & Kang, 2009) Network convergence “transfers several security risks which are present in the IP networks to the telephone network;” imagine denial of service attacks against a VoIP 911 call center. (Fuchs, Aschenbruck, Leder, & Martini, 2008)

As enterprises realize the benefits of initial converged network implementations, new classes and categories of services are being considered for converged networks, especially for multimedia delivery. As Moyer and Umar described in their 2001 article, “The converged network is a key player in e-business and the next-generation applications currently being developed for the growing digital economy.“ (Moyer & Umar, 2001) The author proposes to conduct a review of the research literature concerning the risks and benefits of converged networks in order to better understand this important technological trend.

Understanding Network Convergence

Business Overview

The fundamental change presented by network convergence is to deliver all media via Internet protocol (IP). As Davis described in his 2004 article, “The days when audio, video, and data traveled on separate networks (PSTN, ISDN, Ethernet) to separate devices (phones, room videoconferencing systems, computers) are fast drawing to a close.” (Davis, 2004) Palmieri and Fiore describe the benefits of network convergence specific to telephony, “Voice over Internet Protocol (VoIP) is the future for voice communication and, by using a unique IP infrastructure as the common transport platform, it brings invaluable benefits such as deployment cost reduction, ease of management, ubiquitous coverage and convergence of data and voice together.” (Palmieri & Fiore, 2009) Burger et al explain the factors driving businesses to develop feature-rich applications in the proceedings article, “A telecommunications web services platform for third party network access and SOA-based service delivery,” from 2007

Operator wire line revenues are declining, as are average revenue per mobile subscriber. Network operators need to replace this lost revenue with new applications to acquire new subscribers and keep existing subscribers. Operators need to provide access to their network services in a secure manner to enable content providers to create compelling applications. This drives additional traffic and revenues through the network thereby offsetting depreciating voice-only revenue streams. (Burger, et al., 2007)

The business promise of network convergence is two-fold: reduce operating costs by eliminating legacy systems and provide feature-rich services that are not possible with non-converged networks.

Technological Overview

One of the key technological drivers making network convergence possible is the growth of relatively inexpensive technologies that are able to scale to meet the performance and reliability requirements. As Burger et al describe,

Legacy telecom services were built using C/C++ and CORBA, mostly for performance and scaling reasons. However, the introduction of technologies such as real-time Java Virtual Machines that eliminate the non-deterministic nature of using Java and corresponding gains in general purpose compute platforms, have shown the Java environment in general, and the JEE model in particular, can meet the performance and scale requirements of widespread volume deployments for telecommunications applications. (Burger, et al., 2007)

Burger et al’s discussion is focused on service-oriented architectures (SOA) applied to feature-rich applications running on converged networks. However, the same analysis applies to the underlying physical networks (PSTN, ISDN, Ethernet) and the use of IP.

Another key technological driver enabling successful network convergence is the emergence of interoperability standards focused on IP. Burger et al describe the business impact of standardization by analyzing differences between Sweden and Norway,

For example, if we compare the mobile messaging market in Norway and Sweden during 1990 – 2000, the Swedish market “lost” revenues compared to Norway on the order of 3€/Subscriber/month for approximately 2 Million Subscribers, resulting in a gap of 72 Million Euros per year. The primary reason for this difference was two of the largest mobile operators in Norway deployed access to their messaging services through a common set of APIs. (Burger, et al., 2007)

The development of critical standards governing interoperability, such as quality of service and other IP telephony protocols, is an important technological enabler for network convergence.

Challenges of Network Convergence

Security Risks and Concerns

The operation of converged networks presents a concentration of security risks. On non-converged networks, risks associated with PSTN and ISDN services are segregated from risks associated with Ethernet services. However, on the converged network, all services are exposed to a common pool of threats. Palmieri and Fiore explain that network convergence technology, “becomes a more attractive target for hostile activities, such as session eavesdropping, hijacking and man-in-the-middle attacks.” (Palmieri & Fiore, 2009)

Awais et al describe the impact of denial of service (DoS) and distributed denial of service (DDoS) attacks on converged networks as, “very similar to what can be launched in other classical data networks, but the impact is much more devastating.” (Awais, Farooq, & Javed, 2008) Awais et al explain that the “devastating” impact on converged multimedia networks results because the attack, “will not only affect user registration but also will be damaging for an operator’s resources and assets, as it affects user charging who are already registered to the operator’s network for different services.” (Awais, et al., 2008) Awais et al present an integrated intrusion detection and prevention framework for converged networks that is based on a metaphor of the human immune system. Awais et al evaluate the proposed defensive system and find that it provides improved protection with fewer resources as compared to a signature based detection system. (Awais, et al., 2008)

Fuchs et al highlight the risks of network convergence to critical public safety infrastructure. Fuchs et al present the scenario of a DoS attack against a public safety answering point (PSAP). The PSAP is the emergency services call center that receives 911 calls for a region. As telephony networks converge to IP, the PSAP becomes vulnerable to DoS attacks. (Fuchs, et al., 2008) Fuchs et al develop a methodology for detecting DoS attacks. Within a PSAP, a crucial feature is the ability to distinguish a DoS attack from a disaster, as both appear as a flood of incoming calls, but one requires PSAP response. Fuchs et al’s methodology for detecting DoS attacks against PSAP’s is shown to be able to distinguish and identify DoS attacks. (Fuchs, et al., 2008)

Another security challenge related to network convergence is identity management. Agudo, Lopez, and Montenegro describe identity management limitation imposed by some of the devices found on converged networks,

When delegation is implemented using the attribute certificates in a Privilege Management Infra- structure (PMI), it is possible to reach a considerable level of distributed functionality. However, the approach is not flexible enough for the requirements of ubiquitous environments. The PMI can become a too complex solution for devices such as smartphones and PDAs, where resources are limited. (Agudo, Lopez, & Montenegro, 2008)

Agudo et al propose an attribute-based extension to the Security Assertion Markup Language (SAML). Agudo et al suggest that their proposed methodology solves some of the problems associated with converged network identity management by dividing authorization into two parts, “relation between users implemented by using attribute certificates, and relation between attributes implemented by using attribute subscriptions.” (Agudo, et al., 2008)

Implementation Risks and Concerns

Nolle asserts that network convergence is a market risk to common carriers. Nolle suggests that network convergence requires significant investments from carriers without a certainty of a return on investment. Nolle states, “the service providers interested in convergence tend to be those with stuff to converge: legacy services and legacy networks. That makes them common carriers, not ISPs.” (Nolle, 2005) Further, Nolle states that the revenue stream for converged, IP-based network services is uncertain compared to legacy systems,

Since these services [legacy] in the U.S. currently constitute more than $240 billion in annual revenues, and the U.S. market for Internet services at full business and consumer penetration (including broadband modernization) is probably no more than between $50 billion and $80 billion in annual revenue, this would mean killing more than two-thirds of the current service provider revenues. (Nolle, 2005)

The ongoing adoption and implementation of converged networks seems to imply that industry does not accept Nolle’s assertion of a significant revenue risk.

Benefits of Network Convergence

Next Generation e-Business Applications

Collaboration is a major application area for converged networks. As Davis describes, “users will be able to launch a collaborative session using any one of multiple media (IM, voice, video, and Web) and then seamlessly add other media once the session has been initiated.” (Davis, 2004) As rich collaboration environments develop into robust and effective tools, businesses are able to reduce travel costs for face-to-face meetings.

Burger et al present two use cases for next generation applications that leverage convergence to provide rich features. The first use case describes a content delivery network that includes sale and distribution of music using mobile devices. The second use case describes a mobile news delivery application that provides users with news updates based on subscriptions or content preferences. Both applications leverage the convergence of PSTN, cellular, and Internet networks to deliver content. (Burger, et al., 2007)

Social Networking

The integration of location and presence information from mobile devices with social networks provides another novel and interesting application that relies on converged networks. Burger et al identify this area as an avenue for further research. (Burger, et al., 2007) As Banerjee et al describe in the conclusion of their paper,

[The use case] demonstrates a real-time social networking service that brings together benefits of converged communication capabilities provided by Next-Generation Networks and mature Web 2.0 technologies that are present today. The proposed mashup application can be efficiently deployed by Telecom operators – either as a value-added service or in collaboration with third-party social networking services that are popular in different geographic regions. (Banerjee, Chakraborty, Dasgupta, Mittal, & Nagar, 2008)

As more and more smartphones are deployed with converged networking capabilities, social networking companies like Facebook, Twitter, and MySpace are actively developing location and presence features. In addition, carriers and providers like Verizon and AT&T are also exploring these applications as potential revenue streams.


Staman et al describe converged networks as a critical component for promoting effective communication and learning for online courses, “many of the solutions afforded by converged networks apply to traditional as well as distance learning environments.” (Staman, 2009) Mikoczy et al evaluate the IP Multimedia System (IMS) as an architecture and implementation of television services over IP networks (IPTV). (Mikoczy, Sivchenko, Xu, & Rakocevic, 2007) IPTV represents a convergence of broadcast and IP networks. As the authors explain, the benefits of delivering multimedia over converged networks are significant since, “the user can get access to the IPTV service from any location within the converged access aggregation network developed [for the use case].” (Mikoczy, et al., 2007) Like the IP telephony applications, IMS relies upon quality of service to provide IPTV.


Network convergence is a key enabler for emerging applications such as IPTV, VoIP, location-aware social networks, and media rich content services. Businesses and carriers are driving towards converged networks to reduce operational costs. There are significant security and implementation risks associated with the implementation of converged networks. However, there are mitigations and active research projects working to minimize these dangers.


Agudo, I., Lopez, J., & Montenegro, J. A. (2008). Enabling attribute delegation in ubiquitous environments. Mob. Netw. Appl., 13(3-4), 398-410.

Awais, A., Farooq, M., & Javed, M. Y. (2008). Attack analysis \& bio-inspired security framework for IPMultimedia subsystem. Paper presented at the Proceedings of the 2008 GECCO conference companion on Genetic and evolutionary computation.

Banerjee, N., Chakraborty, D., Dasgupta, K., Mittal, S., & Nagar, S. (2008). R-U-in?: doing what you like, with people whom you like. Paper presented at the Proceeding of the 17th international conference on World Wide Web.

Burger, E. W., Rajasekar, S., O’Doherty, P., Lundqvist, A., Gr\, T., \#246, et al. (2007). A telecommunications web services platform for third party network access and SOA-based service delivery. Paper presented at the Proceedings of the 2007 Workshop on Middleware for next-generation converged networks and applications.

Davis, A. (2004). The Battle For The Enterprise Collaboration Desktop. Business Communications Review, 34(6), 10-12.

Fuchs, C., Aschenbruck, N., Leder, F., & Martini, P. (2008). Detecting VoIP based DoS attacks at the public safety answering point. Paper presented at the Proceedings of the 2008 ACM symposium on Information, computer and communications security.

Jeong, O., Lee, I.-J., & Kang, S.-G. (2009). Design for supporting the multimedia emergency VoIP using PSTN and IP network. Paper presented at the Proceedings of the 2009 International Conference on Hybrid Information Technology.

Mikoczy, E., Sivchenko, D., Xu, B., & Rakocevic, V. (2007). IMS based IPTV services: architecture and implementation. Paper presented at the Proceedings of the 3rd international conference on Mobile multimedia communications.

Moyer, S., & Umar, A. (2001). The Impact of Network Convergence on Telecommunications Software. Communication Magazine, IEEE, 39(1), 78-84.

Nolle, T. (2005). A New Business Layer For IP Networks. Business Communications Review, 35(7), 24-29.

Palmieri, F., & Fiore, U. (2009). Providing true end-to-end security in converged voice over IP infrastructures. [doi: DOI: 10.1016/j.cose.2009.01.004]. Computers & Security, 28(6), 433-449.

Staman, M. (2009). Converged communications, video and innovation in pedagogic settings. Paper presented at the Proceedings of the 10th ACM conference on SIG-information technology education.

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