# An Efficient Delay Tolerant Networks Routing Protocol for Information-Centric Networking
## 1 Introduction
By doing this hop-by-hop forwarding repeatedly, a message can be delivered to the destination node of the message successfully. There have been some works on delivering ICN messages using DTN [8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18]. In these works, networks are generally fragmented due to disaster and DTN protocol is used to deliver ICN messages, where ICN message is encapsulated in DTN message. In [19], research challenge on interworking between ICN and DTN is presented in emergency scenario. It is, however, not efficient to apply DTN protocol to deliver ICN messages directly, since multiple requester nodes exist for the same content and multiple provider nodes exist for the same request in DTN. Therefore, it is necessary to use the characteristics of multiple requester nodes for the same content and multiple provider nodes for the same request in order to deliver Interest and content efficiently. In our preliminary work on delivering ICN messages in DTN [20; 21; 22], we proposed schemes to efficiently deliver Interest and Data using the characteristics of both ICN and DTN. In [20], probabilistic routing protocol using history of encounters and transitivity (PRoPHET) protocol [23] is assumed for DTN protocol and it is extended for efficient ICN message delivery. In PRoPHET protocol, a message is forwarded to another contact node, if the contact node has a higher delivery predictability. In the proposed extension, since a requested Data may exist in multiple caching nodes, delivery predictability is newly calculated between a requester and a set of nodes which have the requested Data. Interests from different requesters with the same content request are merged for reducing overhead of Interest forwarding. In [21], the performance of the proposed protocol in [20] was analyzed using simulation. In [22], we extended our works in [20; 21] to reduce message overhead by sharing successful delivery information of Interest and Data. In this paper, we propose an efficient dissemination of Interest by sharing requester information between nodes efficiently, instead of forwarding Interests during contact. Also, we further improve our preliminary work in [22] by using the information of already delivered Data in order to actively reduce the overhead due to unnecessary dissemination of already delivered Data, based on Vaccine scheme in [24]. In [24], a vaccine scheme was proposed to reduce unnecessary dissemination of already delivered message by actively sharing the successful delivery information, but it is defined for unicast communication with single source node and single destination node in DTN. Therefore, it is not efficient to apply the concept of Vaccine scheme for ICN in DTN directly, since multiple requesters and multiple caching nodes exist together. In this paper, we extended the Vaccine scheme for multiple requesters and multiple caching nodes environment. If Data is already delivered to a requester, the satisfaction flag for a pair of delivered Data and requester is set as 1. Then, if a node with a satisfaction flag of 1 contacts another node with a requester information for the Data corresponding to the satisfaction flag of 1, the requester information is removed from Data in order to avoid unnecessary forwarding of already delivered Data. Finally, Data forwarding between contact nodes is determined by using the average of delivery predictability to a set of requesters of the considered Data, in order to use the characteristics of multiple requesters of the delivered Data. This paper is organized as follows: Section 2 reviews related works in detail. Section 3 illustrates proposed protocol for ICN in DTN. Performance of the proposed protocol is evaluated and compared in Section 4. Finally, Section 5 concludes this work.