End-to-end vs. Hop-by-hop transport under intermittent connectivity (invited paper)

This paper revisits the fundamental trade-off between end-to-end and hop-by-hop transport control. The end-to-end principle has been one of the building blocks of the Internet; but in real-world wireless scenarios, end-to-end connectivity is often intermittent, limiting the performance of end-to-end transport protocols. We use a stochastic model that captures both the availability ratio of links and the duration of link disruptions to represent intermittent connectivity. We compare the performance of end-to-end and hop-by-hop transport over an intermittently-connected path. End-to-end, perhaps surprisingly, may perform better than hop-by-hop transport under long disruption periods. We propose the spaced hop-by-hop policy which is found to dominate (in terms of delivery ratio) the end-to-end policy over the whole parameter range and the basic hop-by-hop policy over most of the relevant range.