| Survivable
Networks Systems
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Definition
Survivability In Network
Systems Contemporary large-scale networked
systems that are highly distributed improve the efficiency and effectiveness of
organizations by permitting whole new levels of organizational integration. However,
such integration is accompanied by elevated risks of intrusion and compromise.
These risks can be mitigated by incorporating survivability capabilities into
an organization's systems. As an emerging discipline, survivability builds on
related fields of study (e.g., security, fault tolerance, safety, reliability,
reuse, performance, verification, and testing) and introduces new concepts and
principles. Survivability focuses on preserving essential services in unbounded
environments, even when systems in such environments are penetrated and compromised. The
New Network Paradigm: Organizational Integration
From their modest beginnings some 20 years ago, computer networks have become
a critical element of modern society. These networks not only have global reach,
they also have impact on virtually every aspect of human endeavor. Network systems
are principal enabling agents in business, industry, government, and defense.
Major economic sectors, including defense, energy, transportation, telecommunications,
manufacturing, financial services, health care, and education, all depend on a
vast array of networks operating on local, national, and global scales. This pervasive
societal dependency on networks magnifies the consequences of intrusions, accidents,
and failures, and amplifies the critical importance of ensuring network survivability.
As organizations seek to improve efficiency and competitiveness, a new network
paradigm is emerging. Networks are being used to achieve radical new levels of
organizational integration. This integration obliterates traditional organizational
boundaries and transforms local operations into components of comprehensive, network-resident
business processes. For example, commercial organizations are integrating operations
with business units, suppliers, and customers through large-scale networks that
enhance communication and services. These
networks combine previously fragmented operations into coherent processes open
to many organizational participants. This new paradigm represents a shift from
bounded networks with central control to unbounded networks. Unbounded networks
are characterized by distributed administrative control without central authority,
limited visibility beyond the boundaries of local administration, and lack of
complete information about the network. At the same time, organizational dependencies
on networks are increasing and risks and consequences of intrusions and compromises
are amplified. The Definition of Survivability
We define survivability as the capability of a system to fulfill its mission,
in a timely manner, in the presence of attacks, failures, or accidents. We use
the term system in the broadest possible sense, including networks and large-scale
systems of systems. The term mission refers to a set of very high-level (i.e.,
abstract) requirements or goals. Missions are
not limited to military settings since any successful organization or project
must have a vision of its objectives whether expressed implicitly or as a formal
mission statement. Judgments as to whether or not a mission has been successfully
fulfilled are typically made in the context of external conditions that may affect
the achievement of that mission. For example, assume that a financial system shuts
down for 12 hours during a period of widespread power outages caused by a hurricane.
If the system preserves the integrity and confidentiality of its data and resumes
its essential services after the period of environmental stress is over, the system
can reasonably be judged to have fulfilled its mission. However, if the same system
shuts down unexpectedly for 12 hours under normal conditions (or under relatively
minor environmental stress) and deprives its users of essential financial services,
the system can reasonably be judged to have failed its mission, even if data integrity
and confidentiality are preserved.
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