In-Network Retransmissions in Named Data Networking

The strategy layer is an important architectural component in both Content-Centric Networking (CCN) and Named Data Networking (NDN). This component introduces a new forwarding model that allows an application to configure its namespace with a forwarding strategy. A core mechanism in every forwarding strategy is the decision of whether to retransmit an unsatisfied Interest or to wait for an application retransmission. While some applications request control of all retransmissions, others rely on the assumption that the strategy will retransmit an Interest when it is not satisfied. Although an application can select the forwarding strategy used in the local host, it cannot guarantee the selection of the same strategy in other nodes in the network, especially in shared resource environments. In some scenarios, a developer must bind the implementation of the application to the details of the deployed forwarding strategy to guarantee the correctness of his application. In this paper we discuss the core mechanisms of a forwarding strategy in NDN, and we explore the importance and impact of in-network retransmissions on the application\u27s performance and correctness. We propose and implement a simple forwarding strategy abstraction that allows the application to decide whether a network retransmission is required, and differentiate application retransmissions from network retransmissions. We show that in some scenarios, such as multiple producers application or multipath consumer-producer service, the proposed abstraction can significantly reduce the percentage of unsatisfied Interests