M. Keshtgary, A.H. Jahangir (Iran), and A.P. Jayasumana (USA)
Survivability, Availability, Fault tree, Excess loss due to
Network survivability refers to the ability of a network to
maintain uninterrupted service regardless of the scale,
magnitude, duration, and the type of failures. There is
growing interest in attempts to quantify the network
survivability in presence of various failures. We perceive
that both performance and availability are integral
components of survivability. Therefore, we propose a
general composite model for survivability performance
evaluation which is applicable to a wide range of
networks. In this model, the excess loss due to failure
(ELF) analysis is used to find the loss due to failure when
the system is operating in gracefully degraded states.
Fault tree method is used to model the availability of the
network and evaluate the cost due to link downtime.
These two models are combined to construct a
hierarchical model to evaluate the network survivability
performance. A packet switched network with UDP
packets is used as an example for this evaluation. We use
network simulator ns-2 to evaluate the proposed model
for packet switched networks. The results from simulation
agree very well with the model.