What is the function of a network I/O control (NIOC) in VMware vSphere?

Network I/O Control (NIOC) in VMware vSphere is designed to manage bandwidth allocation among virtual machines. This feature is crucial in environments where multiple virtual machines share the same physical network resources, as it ensures that critical applications receive the necessary bandwidth during times of high network demand. By implementing NIOC, administrators can prioritize network traffic, define limits, and guarantee minimum bandwidth for specific virtual machines or applications, leading to a more predictable and reliable network performance across the virtual infrastructure.

Overall, the primary function of NIOC is to maintain optimal performance and fairness in bandwidth distribution, thereby preventing any single virtual machine from monopolizing the available network resources. This capability is essential for ensuring quality of service when running multiple applications that may have varying bandwidth requirements.