## 3 Identity-Differentiated Content Acquisition Strategy
### Analysis of Conventional Forwarding Methods  
When transmitting content, MIN-IIoT divides the original content into small data slices to facilitate data communication. In traditional NDN, it is necessary to acquire and combine all data blocks in a sequence to form the original data. In the case of network coding, an interest request for content is not a request for a particular data chunk of the original  
Figure 1: Interest message aggregation process in butterfly network. content but a request for any encoded block of the specific content. We adopt the generation concept introduced by NetCodCCN [13]. In order to reduce the dimensionality of encoding vectors, reduce the complexity of encoding and decoding computing, and facilitate network transmission, we combine several file blocks into a generation and encode them within the same generation. In the future, we will treat generation as an encoding group. The required group number needs to be added after the name identifier when requesting content. In the name identifier \(/pku.edu.cn/web/promo.mp4/1\), \(/pku.edu.cn/web/promo.mp4\) is the name of the content, and 1 is the group number. In MIN-IIoT, handling interest requests for the same content name involves simply looking up the content store (CS) or creating or modifying an FIB entry. Firstly, we analyze two cases of requesting content through unmodified MIN-IIoT. **Scenario 1:** Assume that, in Figure 1, User 1 and User 2 send two interest messages, \(I_{1}\) and \(I_{2}\), respectively, and request the content provider \(A\) to provide two linearly independent encoded blocks named \(/pku.edu.cn/web/promo.mp4\) for encoded group 1 of content \(CC\), with the name identifier as \(/pku.edu.cn/web/promo.mp4/1\). Assuming that edge node F has PIT and CS, \(I_{1}\) and \(I_{2}\) will be aggregated in the pending interest table \(PIT_{F}\) of edge node \(F\) due to the same content name. According to the normal multi-identifier network forwarding process, only one interest message is sent to the provider \(A\). The data will be distributed to Users 1 and 2 until they are returned. **Scenario 2:** Assuming that edge node \(F\) does not have PIT and CS, User 1 sends two interest messages, \(I_{1}\) and \(I_{2}\), through node \(F\), with \(/pku.edu.cn/video/promo.mp4/1\), to request two linearly independent encoded blocks of encoded group 1 provided by the content provider \(A\). The path of \(I_{1}\) is \(F\to B\), while the path of \(I_{2}\) is \(F\to E\to D\to B\), and node \(B\) is the convergence point of the two interest messages. According to the path in the figure, assuming that II arrives at node B before I2, if the traditional NDN-BestRoute forwarding strategy is adopted, only \(F\to B\to A\) is selected as the preferred forwarding path for the communication between content request node \(F\) and the provider \(A\). The \(I_{2}\) interest message may be discarded due to routing reasons, resulting in the waste of I2 transmission. If a multipath forwarding strategy is adopted, \(I_{1}\) first arrives at node \(B\). Then, it creates a table entry for content encoded group 1 in \(B\)'s pending interest table \(PIT_{B}\), as shown in the first line of Table 1. Subsequently, two situations are also considered. **Situation 1:** Before \(I_{2}\) reaches node \(B\), if node \(A\) has already returned encoded data for interest \(I_{1}\), it will cache the data in node \(B\)'s content store \(CS_{B}\). After \(I_{2}\) reaches node \(B\), it directly retrieves the data from \(CS_{B}\) and returns them to node \(F\) along \(B\to D\to E\to F\) in the opposite direction of \(I_{2}\). **Situation 2:** After \(I_{2}\) arrives at node \(B\), node \(A\) has not yet returned a data message. A request interface for the same content will be added to the PIT, as shown in the second line of Table 1, until node \(A\) responds to interest \(I_{1}\) and returns the encoded packet to node \(B\). Node \(B\) responds to node \(F\) along the opposite direction of \(I_{1}\) and \(I_{2}\).