# VNF-Enabled 5G Network Orchestration Framework for Slice Creation, Isolation and Management
## 4 Proposed Strategy
### Slice Isolation by Resource Allocation (SIRA) Scheme
#### 4.2.1 NC-SIRA-based Decision Making  
Prior to receiving the NSR, the node ranking for slices of physical infrastructure should be created. Upon receipt of the NSR, the node ranking for the slices of logical structure is prepared. NCE, NTE, NBE, and NCCE all play an important part in the process of determining the value of each node in the network that is connected to it. As a result, it is imperative that the ranking must be constructed without compromising the intricacies of the nodes' configurations. It is necessary to use PROMETHEE-II in order to create an array of nodes for node ranking based on each node's four characteristics. This technique takes into account the element's individual preferences and disinterestedness. The PROMETHEE-II method for allocating resources for nodes and that consists of the following phases [39; 40]:  
(a) Making an evaluation table: Each node in the evaluation table has its factor values saved in the evaluation table. In order to prepare Table 2, the factors of each node are evaluated with their corresponding weight parameters. It is assumed that \(N=n_{1},n_{2},\ldots,n_{i}\) and \(F=f_{1},f_{2},f_{3},f_{4}\) are the sets of nodes and factors, respectively.  
(b) Function of preferences planning: All nodes in a network are compared to each other in a pairwise comparison for each factor in the network.  
\[d_{k}(n_{i},n_{j})=f_{k}(n_{i})-f_{k}(n_{j}) \tag{15}\]  
where the preference function is introduced to convert the \(d_{k}(n_{i},n_{j})\) unified value as below  
\[P_{k}(a,b)=G_{k}[d_{k}(n_{i},n_{j})] \tag{16}\]  
(c) Calculating a World Preference Index:  
\[\pi(n,m)=\sum_{k=1}^{i}P_{k}(a,b)*w_{k} \tag{17}\]  
where \(w_{k}\) is a weight function of factor \(k\) which is assumed as greater than 0 and the sum of the weights is equal to 1.  
(d) Positive and negative outranking flows are calculated: The following two factors are calculated to locate each node with respect to all other nodes.  
\[\phi^{+}(a)=\frac{1}{i-1}\sum_{x\in A}\pi(a,x) \tag{18}\]  
\[\phi^{-}(a)=\frac{1}{i-1}\sum_{x\in A}\pi(x,a) \tag{19}\]  
where \(\phi^{+}(a)\) is obtained by ranking the nodes according to the nonincreasing values of their respective positive flow values, whereas \(\phi^{-}(a)\) is obtained by ranking the nodes according to the nondecreasing values of their respective negative flow values.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \(f_{1}\) & \(f_{2}\) & \(f_{3}\) & \(f_{4}\) \\ \hline \(n_{1}\) & \(f_{1}(NCE_{n1}^{t})\) & \(f_{2}(NTE_{n1}^{t})\) & \(f_{3}(NBE_{n1}^{t})\) & \(f_{4}(NCCE_{n1}^{t})\) \\ \hline \(n_{2}\) & \(f_{1}(NCE_{n2}^{t})\) & \(f_{2}(NTE_{n2}^{t})\) & \(f_{3}(NBE_{n2}^{t})\) & \(f_{4}(NCCE_{n2}^{t})\) \\ \hline. &. &. &. &. \\ \hline. &. &. &. &. \\ \hline \(n_{i}\) & \(f_{1}(NCE_{ni}^{t})\) & \(f_{2}(NTE_{ni}^{t})\) & \(f_{3}(NBE_{ni}^{t})\) & \(f_{4}(NCCE_{ni}^{t})\) \\ \hline \hline \end{tabular}
\end{table}
Table 2: Evaluation table.  
(e) Net flow calculation:  
\[\phi(a)=\phi^{+}(a)-\phi^{-}(a) \tag{20}\]  
The highest value of \(\phi(a)\) refers to the best node in the node ranking (NR). After implementing NC-SIRA-based node allocation, the algorithm described in [40] is used to return the details of the NSR nodes that have been assigned in PI. Every time a new NSR is received, this procedure is carried out. The revised values of unsuccessful NSR (usNSR) and successful NSR (sNSR) are obtained at the conclusion of the execution.