# An Efficient Delay Tolerant Networks Routing Protocol for Information-Centric Networking
## 2 Related Works  
In this section, related works on ICN in DTN are surveyed in detail. In [8], the authors proposed an integrated ICN and DTN protocol. In DTN, routing based on the reverse path stored in PIT is not available due to the disconnection between nodes and the mobility of nodes. The authors propose to use DTN protocol for routing and forwarding of ICN in disconnected environment. ICN Interests are carried in payload of DTN messages, and if any node has a content for the Interest, the content is carried in payload of DTN messages to requesters. Bundle protocol query extension block is used for this interworking between ICN and DTN. In [9], agent-based content retrieval (ACR) scheme was proposed, where requesters delegate content retrieval to mobile agents and mobile agents retrieve contents on behalf of the requesters. If requesters and agents contact again, requesters retrieve contents from agents. The ACR scheme consists of three phases: (1) agent delegation, (2) content retrieval, and (3) content notification. In agent delegation phase, an agent is searched for and content retrieval is delegated to the agent. In content retrieval phase, agent finds and retrieves content for the requester by broadcasting Interest periodically. In content notification, if an agent retrieves content, it notifies it to the requester by performing either push or pull notification. In [10], the authors proposed content centric DTN network architecture, where multi-hop cellular network (MCN) is considered. In MCN, user devices communicate with each other using either cellular base station or device-to-device (D2D) communication. The proposed protocol consists of three planes: (1) control plane, (2) forwarding plane, and (3) routing decision plane. In control plane, meta-information is inserted in the DTN messages based on the packet type (Interest/Data). In forwarding plane, either ICN forwarding or DTN forwarding is selected. Mobile node uses DTN to forward packets in D2D way. Pending requester information table (PRIT) is defined to store requester information instead of arrival faces of Interest. In routing decision engine, request/response processing and content management are carried out. In [11], the authors proposed an information centric delay tolerant network model based on the similarities between them, i.e., (1) in-network storage, (2) late binding, (3) data longevity, and (4) flexible routing. In order to show the advantages of information centric delay tolerant networks, the authors carried out simulations and compared two communication modes, i.e., information-centric and host-centric. In [12], the authors proposed a delay tolerant ICN for disaster management in fragmented networks due to disaster. Each fragmented network has a gateway which collects messages exchanged with external fragmented networks. Communication between fragmented networks is carried out by data mules such as ambulances, police-cars, and people, which have different movement patterns. Each data mule has encounter table which has delivery probability value with destinationsand message, and each message has a priority. Based on probability value and message priority, transmission priority is determined and a message with a higher transmission priority is transmitted earlier. In [13; 14], the authors proposed a data discovery and retrieval based on social cooperation in content-centric delay tolerant network, where relay nodes are selected based on social cooperation criterion, in order to reduce content discovery and recovery latency. They define social relationship factor between two nodes based on past contact history, where total number of encounters between two nodes and encounter function which measures the elapsed time since the last contact are used to calculate social relationship. The proposed protocol consists of three phases: (1) distribution phase, (2) search phase, and (3) return phase. In the distribution phase, content information is disseminated by either producer nodes or expert nodes who received content from producer nodes.