Congestion management in delay tolerant networks

In delay tolerant networks, custody transfer can provide certain degree of reliabili ty as a custodian node cannot discard a message unlessits li fe time expires or the custody is transferred to another node after a commitment. This creates a challenging decision making problem at a node in determining whether to accept a custody transfer: on one hand, it is beneficial to accept a large number of messages as it can potentially advance the messages toward their ultimate destinations and network utili zation can be maximized; on the other hand, if the receiving node overcommits itself by accepting too many messages, it may find itself sett ing aside an excessive amount of storage and thereby preventing itself f rom receiving fur ther potentially impor tant, high yield (in terms of network utili zation) messages. To solve this problem, in this paper, we apply the concept of revenue management, and employ dynamic programming to develop a congestion management strategy for delay tolerant networks. For a class of network utili ty functions, we show that the optimal solution is completely distr ibuted in nature where only the local information such as available storage space of a node is required. This is par ticular ly important given the nature of delay tolerant networks where global information is often not available and the network is inherently dynamic. Our simulation results show that the proposed congestion management scheme is effective in avoiding congestion and balancing network load among the nodes.