attached processors and databases. This evolution was clearly necessary to support the ubiquity of interconnections, increases in call volume, and provision of new services. The resulting network has proven generally reliable and secure. But like all networks, it is potentially vulnerable to electronic attack.6

Data networks, and the Internet in particular, evolved in a very different way. The Internet began as an open collaboration among trusted peers. The protocols were developed to optimize interconnection, simplicity, and access—characteristics that have proven to be some of the Internet’s greatest strengths, adding to its reliability and scalability. But while redundancy and distribution were contemplated, security and quality of service were not prominent concerns early on. Despite the demonstrated advantages of the current architecture, every device connected to the Internet can become a source of or a target for malicious activity. And such malicious activity has flourished, most publicly in the form of hackers/crackers, viruses, worms, Trojan horses, or denial-of-service attacks. Today both the network and every networked device requires some form of protection, but the protection is neither uniform nor universal.

Trustworthiness issues also arise at the intersection of the public telephone network and the Internet. Initially, voice and data network interaction was limited to common transport systems and the use of the voice network to carry data between dial-up modems. Today, digital subscriber line (DSL) services carry data over the same lines that formerly carried only voice conversations. The volume of data traffic now surpasses the volume for voice traffic, a development that forces consideration of the eventual migration of voice traffic to the data network. In fact, this migration has begun—albeit more slowly than initially projected—with voice over IP (VoIP), IP Centrex, and softswitch technology. Over time voice traffic will increasingly be carried by packet transport and routing. In the interim, interworking between the traditional public switched telephone network and the data networks must be provided. Convergence of the voice and data networks, although compelling in features and potential cost savings, also requires research into the reliability and security of existing voice services and the overall converged network.

In addition to convergence, new technologies are also enabling new network capabilities and services that will in turn pose new challenges to trustworthiness. Dense wavelength-division multiplexing (DWDM), optical switching, a migration of Ethernet into metropolitan networks, virtual private networking, multiprotocol label switching (MPLS), video, unified messaging, and various forms of wireless data all require intelligent network components or devices. Devices and services for personal computing, mobile Internet use, and a plethora of other applications that will leverage these emerging capabilities will also bring more complexity into the core and edges of the network—and thus new challenges to ensuring security and reliability.

Public data networks have been built and the number of network providers—including 30 major Internet backbone providers and thousands of Internet service providers—has increased at an unprecedented rate. As a result of all these rapid changes, public networks now have many more interfaces to competing networks and therefore many more points of vulner-


Reflecting the network’s national importance, additional measures (e.g., planning, coordination, and information sharing via creation of entities such as the National Security Telecommunications Advisory Committee and the National Coordinating Center for Telecommunications) have been taken to help avert attacks and remediate their consequences.

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