On/off process modeling of IP network failures

A reliability model for IP networks is considered, where the routers and links are modeled by independent stationary on/off processes. Component downtimes may obey any probability distribution. The model combines component reliability to a topological analysis, taking into account the routing rules of the network. This allows the derivation of on-off processes describing with high accuracy the IP-availability delivered to customers of each access router. The approach also provides estimates for risk in terms of lost traffic and allows analytic comparison of basic strategies for reliability improvement. The methodology is illustrated by studying the Finnish research backbone network.