Virtualization enables the collective use of hardware resources. Hence, it is an important factor, specifically for server consolidation when it comes to saving management, space, and energy costs. One research area is the network. It is definitely difficult to identify factors that will create a performance bottleneck; hence, we will start with the following influencing factors:
Choosing a physical switch
Choosing the right virtual switch
Sizing the Ethernet capacity
Choosing the right enhancers
Choosing the ESXi server architecture to accommodate the network
The listed factors are crucial. You may consider other factors based on your requirements; hence, this is not a comprehensive list of factors, but this is more than enough to get started.