## 2 Related Works
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Ref\#** & **Strategy** & **Scenario** & **Contribution** \\ \hline \multicolumn{4}{l}{Virtual Network Embedding (VNE)} \\ \hline
[27] & Exact & Cloud &
\begin{tabular}{c} Introduced a Green Virtual Network Embedding (GVNE) framework to \\ minimize energy consumption. \\ \end{tabular} \\ \hline
[28] & Heuristic & Data center &
\begin{tabular}{c} Proposed Markov Chain-based Algorithm for VNE (MCA-VNE) to \\ minimize request rejection and maximize revenues. \\ \end{tabular} \\ \hline
[29] & Heuristic & Cloud &
\begin{tabular}{c} Proposed SR-VNE algorithm to maximize revenue and acceptance in \\ long term. \\ \end{tabular} \\ \hline
[30] & Heuristic & \
\begin{tabular}{c} Service \\ provider \\ network \\ \end{tabular} &
\begin{tabular}{c} Proposed MaVEn-M and MaVEn-S algorithms using the \\ multi-commodity flow and Markov decision processes to \\ maximize revenue. \\ \end{tabular} \\ \hline
[31] & heuristic & Cloud &
\begin{tabular}{c} proposed Adaptive-VNE algorithm to maximize revenue, acceptance, \\ and end-user satisfaction. \\ \end{tabular} \\ \hline \multicolumn{4}{l}{Virtual Network Function Placement (VNF-P)} \\ \hline
[33] & \begin{tabular}{c} Heuristic, \\ Metaheuristic \\ \end{tabular} & \
\begin{tabular}{c} Operator \\ network \\ \end{tabular} &
\begin{tabular}{c} Proposed three greedy and a tabu search-based algorithms for VNF \\ embedding and process scheduling to maximize revenue. \\ \end{tabular} \\ \hline
[34; 35] & \begin{tabular}{c} Exact, \\ Metaheuristic \\ \end{tabular} & \
\begin{tabular}{c} Operator \\ network \\ \end{tabular} &
\begin{tabular}{c} Formulated VNFs chaining scheduling as problem as a series of \\ scheduling decisions for services to minimize scheduling latency. \\ \end{tabular} \\ \hline
[36] & \begin{tabular}{c} Exact, \\ Heuristic \\ \end{tabular} & \
\begin{tabular}{c} Mobile \\ network \\ \end{tabular} &
\begin{tabular}{c} Proposed a proof of concept that NFV management can be extended to \\ the radio segment of mobile network. \\ \end{tabular} \\ \hline
[37] & \begin{tabular}{c} Exact, \\ Heuristic \\ \end{tabular} & \
\begin{tabular}{c} Operator \\ network \\ \end{tabular} &
\begin{tabular}{c} Proposed an ILP formulation for VNF orchestration problem and a \\ dynamic programming heuristic to minimize the operational cost and \\ physical resource fragmentation. \\ \end{tabular} \\ \hline
[38] & Heuristic & \
\begin{tabular}{c} Operator \\ cloud \\ \end{tabular} &
\begin{tabular}{c} Proposed a placement algorithms with two objectives and used \\ bargaining Nash theory to find a fair trade-off between them to \\ minimize end-to-end path and user’s mobility. \\ \hline \multicolumn{4}{l}{Service Function Chaining Placement Problem (SFC-FP)} \\ \hline
[24] & Heuristic & \
\begin{tabular}{c} Operator \\ network \\ \end{tabular} &
\begin{tabular}{c} Proposed a primary backup redundant scheme mapping to maximize \\ the service continuity. \\ \end{tabular} \\ \hline
[11] & \begin{tabular}{c} Exact, \\ Heuristic \\ \end{tabular} & \
\begin{tabular}{c} Service \\ provider \\ network \\ \end{tabular} &
\begin{tabular}{c} Proposed NF decomposition selection based on VNF clustering using \\ virtualization technique type to minimize mapping cost. \\ \end{tabular} \\ \hline
[12] & \begin{tabular}{c} Exact, \\ Heuristic \\ \end{tabular} & \
\begin{tabular}{c} Operator \\ network \\ \end{tabular} &
\begin{tabular}{c} Proposed a SFC placement with function scalability to realize the \\ dynamic operations on NFV. \\ \end{tabular} \\ \hline
[42] & Heuristic & \
\begin{tabular}{c} Operator \\ network \\ \end{tabular} &
\begin{tabular}{c} Proposed a consolidation algorithm based on migration policy to reduce \\ the cost of QoS degradation during VNF migration. \\ \end{tabular} \\ \hline
[43] & Heuristic & NFV network &
\begin{tabular}{c} Presented an automatic policy-based approach to solve service chain \\ composition on NFV or reduce operational cost. \\ \end{tabular} \\ \hline
[44] & \begin{tabular}{c} Exact, \\ Heuristic \\ \end{tabular} & \
\begin{tabular}{c} Operator \\ network \\ \end{tabular} &
\begin{tabular}{c} Proposed a NF Consolidation on NFV to minimize resource occupation \\ by reducing the number of VNF. \\ \end{tabular} \\ \hline
[45] & \begin{tabular}{c} Exact, \\ Heuristic \\ \end{tabular} & \
\begin{tabular}{c} Optical \\ network \\ \end{tabular} &
\begin{tabular}{c} Proposed placement algorithm based on game theory to minimize \\ mapping cost. \\ \end{tabular} \\ \hline
[46] & Heuristic & Data center &
\begin{tabular}{c} Optimized VNF placement and service chaining using a Markov \\ approximation with many-to-one matching theory in coordinated \\ approach to minimize the cost. \\ \end{tabular} \\ \hline
[47] & \
\begin{tabular}{c} Exact, \\ Heuristic \\ \end{tabular} & NFVI &
\begin{tabular}{c} Proposed a coordinated approach to jointly optimize NFV-RA in the \\ three stages of the problem. \\ \end{tabular} \\ \hline
[48] & \begin{tabular}{c} Exact \\ network \\ \end{tabular} & \
\begin{tabular}{c} Hybrid \\ network \\ \end{tabular} &
\begin{tabular}{c} Proposed a customizable SFC composition to minimize the mapping and \\ the management cost. \\ \end{tabular} \\ \hline
[49] & \begin{tabular}{c} Exact, \\ Heuristic \\ \end{tabular} & \
\begin{tabular}{c} Service \\ provider \\ network \\ \end{tabular} &
\begin{tabular}{c} Proposed a survivability for SFC with multi-path link mapping in order \\ to maximize survivability and minimize resource redundancy \\ \end{tabular} \\ \hline
[50] & Heuristic & Cloud &
\begin{tabular}{c} Proposed an eigen-decomposition based approach to maximize \\ revenues. \\ \end{tabular} \\ \hline
[51] & Heuristic & NFV network &
\begin{tabular}{c} Proposed a coordinated placement algorithm that solves service chain \\ composition and embedding with reasonable execution time in \\ large-scale physical networks. \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table}