Churn, churn, churn

Churn, churn, churn: how instability of health insurance shapes America's uninsured problem.

A new analysis of health insurance coverage in America reveals a complex and troubling picture of insurance instability and gaps in coverage over time. Eighty-five million people, or 38 percent of the population under age 65, were uninsured at some point from 1996 through 1999, based on findings from a survey that followed people’s health coverage for four years (Chart 1).The number of people w...

Mojito under Churn

In a dynamic hash table (DHT), peers in a network cooperate to maintain a distributed keyvalue storage. Each peer in a DHT is responsible for storing a subset of keys and their values. Especially in a peer-to-peer system, the peers may not be stable. New peers join and existing peers either fail or leave the system. This process, called churn, requires the DHT to be able to reorganize itself. T...

Maelstrom: Churn as Shelter

Structured overlays are an important and powerful class of overlay networks that has emerged in recent years. They are typically targeted at peer-to-peer deployments involving millions of user-managed machines on the Internet. In this paper we address routing-table poisoning attacks against structured overlays, in which adversaries attempt to intercept traffic and control the system by convinci...

Churn in Social Networks

Infinite Unlimited Churn

We study unlimited infinite churn in peer-to-peer overlay networks. Under this churn, arbitrary many peers may concurrently request to join or leave the overlay network; moreover these requests may never stop coming. We prove that unlimited adversarial churn, where processes may just exit the overlay network, is unsolvable. We focus on cooperative churn where exiting processes participate in th...