# Comprehensive Comparison of VNE Solutions Based on Different Coordination Approaches
## 4 Evaluation of Examined Solutions
### Evaluation Results
#### 4.5.1 Variations on CPU and BW Demands  
Acceptance Ratio (AR)--While the examined scenarios shift between progressively increased CPU and BW demands, the studied solutions exhibit different variations in  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{4}{c}{**Virtual Network**} \\ \hline \multirow{2}{*}{**Scenario ID**} & **Number** & **Nodes** & **CPU** & **BW** \\  & **of VNRs** & **per VNR** & **Cycles** & **Units** \\ \hline s-id1 & 20 & 10 & 15 & 15 \\ \hline s-id2 & 20 & 10 & 15 & 30 \\ \hline s-id3 & 20 & 10 & 15 & 50 \\ \hline s-id4 & 20 & 10 & 15 & 70 \\ \hline s-id5 & 20 & 10 & 30 & 15 \\ \hline s-id6 & 20 & 10 & 30 & 30 \\ \hline s-id7 & 20 & 10 & 30 & 50 \\ \hline s-id8 & 20 success rates. More specifically, the single stage coordination algorithms exceed all the rest in successfully accepted incoming VNRs, as Figure 3a illustrates. They achieve such a performance by also maintaining a stable and relatively reasonable decrease in AR percentages as the intensity of the demand in CPU and BW resources steadily increase. On the contrary, the two stages coordination and the uncoordinated techniques provide less stable acceptance results as the demands intensify, especially those variants that employ the k-shortest path link mapping algorithm. The two stages coordination, however, outperforms the latter in every examined scenario. Equivalent performance behavior is also observed, regarding the few-large experimental orientation with prospectively lower AR percentages, as depicted in Figure 3b. Nevertheless, the success rates of the uncoordinated solutions collapse dramatically faster in contrast to their coordinated counterparts, proving that denser VNRs pose as a heavier task for that category of VNE algorithms. Running Time (RT)--The solutions that incorporate the SID method obtain successful results in undeniably lower execution times in comparison to the other strategies. By the RT graphs, depicted in Figure 4, it is made clear that the SID-based solutions are faster in either the many-small and the few-large orientations. Even so, the AdvancedVNMFlib demands greater RT values regarding the more demanding VNRs due to the variable nature of the SLL parameter in contrast to the SimpleVNMFlib (see Section 3.2.2). The backtracking process of the AdvancedVNMFlib is a time consuming mechanism and, for denser demands, provides no better results than the faster SimpleVNMFlib. The greatest toll on execution time was taken by those strategies utilizing the two stages coordination node and link mapping technique. As the RT graphs of Figure 4 illustrate, the time needed for the two-stage solutions to perform is many times greater than the other opposed ones, exhibiting high complexity in the VNM and VLM calculation steps of this coordination category. The uncoordinated solutions appear to achieve equivalent execution times to their single stage counterparts. However, they do so by lacking in AR percentages as was aforementioned. Figure 3: Success rates of the examined embedding strategies. Cost/Revenue multiplied by Mapped Revenue (CR*MR)--The SimpleVNMFilib implementation that incorporates a 10-hop static SLL value and invokes inflexibly and constantly longer network paths in comparison to the AdvancedVNMFilib alternative, which supports values from 1 to 10. Furthermore, while the two stages coordination and uncoordinated strategies appear to perform more efficiently over SimpleVNMFilib regarding the CR*MR index, AdvancedVNMFilib achieves embeddings that are noticeably of lower cost during both scenario orientations. In addition, as depicted in Figure 5, the cost of the embeddings that D-ViNE-PS and Greedy-PS achieve, is lower in comparison to D-ViNE-SP and Greedy-kSP, respectively, in almost every scenario due to the use the multipath approach and the flexibility it provides. Active Node Stress (ANSTRESS)--The two stages coordination and the uncoordinated orientations tend to provide an even distribution of mapped resources, because of their adopted methodology.