MeDeHa - Efficient Message Delivery in Heterogeneous Networks with Intermittent Connectivity
Résumé
In this report, we present an efficient message delivery mechanism that enables distribution/dissemination of messages in an internet connecting heterogeneous networks and prone to disruptions in connectivity. We call our protocol MeDeHa (pronounced ``medea'') for Message Delivery in Heterogeneous, Disruption-prone Networks. MeDeHa is complementary to the IRTF's Bundle Architecture: while the Bundle Architecture provides storage above the transport layer in order to enable interoperability among networks that support different types of transport protocols, MeDeHa is able to store data at any layer of the network stack, addressing heterogeneity even at lower layers (e.g., when intermediate nodes do not support higher-layer protocols). MeDeHa also takes advantage of network heterogeneity (e.g., nodes supporting more than one network and nodes having diverse resources) to improve message delivery. For example, in the case of IEEE 802.11 networks, participating nodes may use both infrastructure- and ad hoc modes to deliver data to otherwise unavailable destinations. Another important feature of MeDeHa is that it does not rely on special-purpose nodes such as message ferries, data mules, or throwboxes in order to relay data to intended destinations, and/or to connect to the backbone network wherever infrastructure is available. The network is able to store data destined to temporarily unavailable nodes for some time depending upon current storage availability as well as quality-of-service needs (e.g., delivery delay bounds) imposed by the application. We showcase MeDeHa's ability to operate in environments consisting of a diverse set of interconnected networks and evaluate its performance via extensive simulations using a variety of synthetic-- as well as more realistic scenarios. Our results show significant improvement in average delivery ratio and significant decrease in average delivery delay in the face of episodic connectivity. We also demonstrate MeDeHa's support for different levels of quality-of-service through traffic differentiation and message prioritization.
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