# An Efficient Delay Tolerant Networks Routing Protocol for Information-Centric Networking
## 1 Introduction  
Information-Centric Networking (ICN) [1; 2; 3] was proposed to overcome the current bottleneck problem of the Internet due to overwhelming content downloads. In the Internet, routing is carried out based on the IP address of destination node. If a node sends a content request packet, it is routed through intermediate routers based on the IP address of the destination node, i.e., content server. Therefore, if multiple users request the same content downloads, multiple unicast downloads from a content server are generated, even though the routing paths of those sessions may overlap significantly, and they consume significant network bandwidth. In ICN, on the other hand, content name is used to search for a content instead of IP address, and content is cached in intermediate nodes as well as an original content server for efficient content delivery. In ICN, a node which requests a content is called a consumer, and a node which generates a content is called a provider. For name-based routing, Pending Interest Table (PIT), Content Store (CS), and Forwarding Information Base (FIB) are defined in ICN [1; 2; 3]. PIT stores input interface, which is called a face in ICN, of the received Interest packet. CS acts as the caching storage of an ICN node. FIB manages forwarding information for requested content, i.e., Data. If a consumer wants to download content, it transmits Interest for the requested content to neighbor nodes. A node whichreceives the Interest records the input face of the Interest in its PIT and checks for its CS firstly to see if there is the requested content. If there is, it returns the content to the incoming face. Otherwise, it checks FIB table to find appropriate outgoing face for the requested Interest. If Interest is arrived at either a node with the requested content in its CS or an original content provider, the content is replied back to the consumer along the reverse path of forwarding path of Interest using PIT, and content may be cached in the CS of intermediate nodes. Therefore, ICN can solve the current bottleneck problem of the Internet, by using the name of content for routing and returning of content from nearby caching node. Recently, the importance of an efficient communication in disaster environment has been increased, especially to save the life of the survivors effectively. The current cellular network or Internet may not be efficient in a disaster environment because survivors may not be aware of appropriate point of contacts, i.e., phone number or IP address. Also, communication between dynamically formed rescue team members is not efficient in current communication technology [4]. ICN is suitable in this disaster environment, since a name is used to send messages and responses are quickly returned from nearby caching nodes. Furthermore, communication between rescue team members can be achieved easily using a flexible name structure, and dynamic grouping of team members is very efficiently achieved [4]. Network infrastructure for ICN, however, is unlikely to be available in disaster environment due to the destruction of infrastructure. Thus, infrastructure-based networks such as cellular networks or Internet are not applicable. Since network connectivity may not be guaranteed due to the sparse density of nodes in disaster environment, mobile ad-hoc networks (MANET) is not applicable. Therefore, a new communication method should be applied to enable ICN message delivery in disaster environment, and delay tolerant networks (DTN) can be a good candidate for this situation. In DTN, communication is possible without infrastructure and a message can be delivered, even though there is no guaranteed end-to-end routing path between a source node and a destination node by using a'store-carry-forward' approach [5; 6; 7]. A node with a message to deliver stores it in its buffer, which is operated in bundle layer. If it contacts another node while moving, it forwards the message to the contact nodes, based on a predefined criteria.