## 3 ICN Architecture  
ICNs were created in a desire to move from host-centric networking to information-centric networking. These networks function by labeling information. This naming of information means that every piece of information that can be requested has a label that will be referred to in this paper as an ICN name. Communication is driven by consumers who request information utilizing an Interest PDU with the desired ICN name. Nodes who participate in this network, each identified as a Content Router (CR), forward the Interest PDU until the corresponding information to the ICN name is found. The information is returned in a Data PDU which uses the ICN name. To carry out Interest and Data PDU forwarding, each CR maintains three data structures, a Pending Interest Table (PIT), a Forwarding Information Base (FIB) and a Content Store (CS). The PIT stores all the Interests that a CR has forwarded but not yet satisfied. Each PIT entry keeps track of the ICN name solicited along with its incoming interface. The FIB keeps entries which map ICN names to interfaces. These entries are leveraged by algorithms, named forwarding strategies, to determine where to forward Interest PDUs by their ICN names. The upstream and downstream flow of Interest and Data PDUs are shown in Figures 1 and 2. When an Interest PDU arrives at a CR, the CR checks the CS for information matching the ICN name used in the Interest PDU. If a match exists, the CR returns the information in a Data PDU on the interface from which the Interest PDU arrived. Otherwise, the ICN name is looked up in the PIT and, if a matching entry exists, the incoming interface identifier is aggregated to the PIT entry. A forwarding strategy is then utilized to forward the Interest PDU. When a Data PDU arrives, the CR finds the matching PIT entry and forwards the Data PDU to all downstream interfaces listed in the PIT entry. Once the Data PDU is forwarded, the PIT entry is removed and the information in the Data PDU is stored in the CS for future use. The maintenance and cooperation of CSs in an ICN are some of the key elements to obtain a high user Quality of Experience (QoE). How CSs cooperate is a topic that continues to present interesting solutions [17; 18]. Another key element to obtain a high user QoE in ICN is the selection of an appropriate forwarding strategy. Forwarding strategies determine where received Interest PDUs should be transmitted. Usually, the forwarding strategy is linked with the FIB, but this varies depending on the ICN implementation. Since forwarding strategies are usually based on the mapping of ICN names to possible transmission locations, Sections 3.1 and 3.3.1 are dedicated to describing these strategies in more detail. Figure 1: Forwarding process for Interest PDUs at an ICN node. For Named-Data Networking (NDN), one of the main ICN implementations, there is no mention of a network naming structure for the architecture's main namespace [19]. A structure is implied with the use of URLs in its presentation. There is also an understanding that individual links to connect CRs would be managed by existing networks. In subsequent work, the main namespace design only assumes hierarchically structured names. Namespace management is declared not to be part of the architecture, leaving it up to users to define namespace structures and management for their needs. According to [20], naming is considered to be the most important part of NDN application design, as it enables the architecture's advantages. However, a naming guideline is not presented. An analysis of ICN naming, utilizing an interpretation of [PERSON]'s work, can be found in [12]. Once again, a naming guideline is not presented. With the ICN architecture reimplementing network naming strategies from previous network designs, such as in [21], it is unclear if known naming issues are not being introduced into the network architecture. The lack of a guideline for mapping the ICN namespace to existing networks causes issues for broadcast mediums.