# IMU: A Content Replacement Policy for CCN, Based on Immutance Content Selection
## 5 Conclusions and Future Work  
In-network caching is one of the essential features in the CCN architecture network, allowing content items to be cached in the router nodes for some time, to meet subsequent consumer requests. Due to the limited cache capacity in the node, any cached content in the cache needs to be evicted to accommodate new content. Content replacement policy is responsible for choosing the right content against defined criteria. Existing cache replacement policies use the concept of popularity or time for content eviction. However, when content loses its popularity after becoming very popular in a certain period, it remains in the cache space. Moreover, content is evicted from the cache space before it becomes popular. Therefore, the proposed policy handles cached items that lose their popularity over a specific time frame and remain in the cache for a long time. We introduced the new concept of content maturity and immaturity for content eviction in CCN. The  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \(\mathbf{\alpha}\) & **Cache Size** & **Placement** & **FIFO (\%)** & **LRU (\%)** & **LFU (\%)** & **LFRU (\%)** \\ \hline
0.6 & & LCE & 15.58 & 12.34 & 11.49 & 9.30 \\
0.6 & & CL4M & 14.83 & 10.52 & 10.34 & 8.46 \\
0.6 & 4\% to 20\% & ProbCache & 13.45 & 10.40 & 10.30 & 7.61 \\
0.6 & & LCD & 17.08 & 13.71 & 12.93 & 9.68 \\
0.6 & & opt-Cache & 15.07 & 10.43 & 10.27 & 6.10 \\ \hline
0.8 & & LCE & 20.32 & 17.19 & 17.19 & 14.40 \\
0.8 & & CL4M & 21.54 & 18.04 & 17.45 & 15.28 \\
0.8 & 4\% to 20\% & ProbCache & 19.18 & 16.17 & 14.95 & 12.04 \\
0.8 & & LCD & 23.44 & 18.48 & 16.51 & 14.64 \\
0.8 & & opt-Cache & 22.03 & 11.74 & 9.19 & 6.97 \\ \hline
1.0 & & LCE & 20.89 & 17.40 & 15.27 & 13.09 \\
1.0 & & CL4M & 16.10 & 11.15 & 9.99 & 5.95 \\
1.0 & 4\% to 20\% & ProbCache & 16.23 & 12.78 & 11.73 & 7.43 \\
1.0 & & LCD & 17.56 & 11.62 & 9.37 & 6.40 \\
1.0 & & opt-Cache & 17.30 & 12.14 & 10.35 & 5.55 \\ \hline \hline \end{tabular}
\end{table}
Table 13: IMU link load percentage improvement.  
proposed content replacement policy (IMU) uses the concept of maturity/immaturity of the content. This policy finds the content maturity index by using the content arrival time and its frequency. Also, it determines the maturity level through a maturity classifier. We have performed extensive simulations to evaluate the proposed content replacement policy, using the Icarus simulator under different cache sizes and content popularity. The simulation results indicate that the proposed policy outperformed recent and baseline content replacement policies (FIFO, LRU, LFU, and LFRU). The results demonstrate that the proposed policy is better in terms of the cache hit ratio, latency, path stretch, and link load. In the future, this work can be extended to use the content replacement policy (IMU) with different constraints in different use cases. Another potential future work is in-depth investigation of content diversity for the nodes with very high content popularity.  
Conceptualization, S.R., S.A.R. and F.A.G.; methodology, S.R.; software, S.R.; validation, S.R., S.A.R. and F.A.G.; formal analysis, S.R. and F.A.G.; investigation, S.R., S.A.R. and F.A.G.; writing--original draft preparation, S.R.; writing--review and editing, S.R., S.A.R. and F.A.G.; supervision, S.A.R. and F.A.G.; funding acquisition, S.A.R. All authors have read and agreed to the published version of the manuscript. This work was supported by the Universiti Teknologi Malaysia (UTM) under UTM Research University Grant Scheme: (VOT Q.J130000.3613.03M41), Universiti Teknologi Malaysia, Johro Bahru, Malaysia.  
Not applicable.  
The authors declare no conflict of interest.