olerance is the ability of a system to tolerate disruptions in connectivity among its components, consisting of the environmental challenges: weak and episodic channel connectivity, mobility, unpredictably-long delay, as well as tolerance of energy (or power) challenges. Resilience and Survivability in Communication Networks: Strategies, Principles, and Survey of Disciplines -J.P.G. Sterbenz et al. (2010) Disciplines of Network Resilience So how do we make the network more resilient? J.P.G. Sterbenz et al. classify the disciplines related to resilience under the following categories of challenge tolerance and trustworthiness: Challenge tolerance. As can be inferred, this relates to how the network continues to provide services on the face of challenges based on its design and engineering strengths. This could be broken down further into the following categories: Fault tolerance: Relating to the ability of the network to be able to handle and contain fault situations from escalating to system-level issues, leading to service disruptions. Relying primarily on redundancy techniques, fault tolerance can be seen as a way of handling noncorrelated fault events of limited scope. Survivability: A discipline that extends fault tolerance to more complicated scenarios where correlated fault events are being witnessed in the network. These could be malicious intentional coordinated efforts to bring the network down or an unintentional chain of events caused by large-scale disasters, both natural and manmade. Measures to define survivability have been suggested based on the factors drawn from Towards a Rigorous Definition of Information System Survivability by John C. Knight, Elisabeth A. Strunk, and Kevin J. Sullivan as a sextuple specification based on: Set of acceptable service states Set of service value factors Reachable environmental states that the system is subject to, which normally represent the challenges for the system Ordered relative service values as experienced by the user Set of valid transitions that the sys