Isolation of network traffic is essential to a secure ESXi environment. Different networks require different access and level of isolation.
Your ESXi host uses several networks. Use appropriate security measures for each network, and isolate traffic for specific applications and functions. For example, ensure that vSphere vMotion traffic does not travel over networks where virtual machines are located. Isolation prevents snooping. Having separate networks also is recommended for performance reasons.
vSphere infrastructure networks are used for features such as VMware vSphere vMotion®, VMware vSphere Fault Tolerance, and storage. These networks are considered to be isolated for their specific functions and often are not routed outside a single physical set of server racks.
A management network isolates client traffic, command-line interface (CLI) or API traffic, and third-party software traffic from normal traffic. This network should be accessible only by system, network, and security administrators. Use jump box or virtual private network (VPN) to secure access to the management network. Strictly control access within this network to potential sources of malware.
Virtual machine traffic can flow over one or many networks. You can enhance the isolation of virtual machines by using virtual firewall solutions that set firewall rules at the virtual network controller. These settings travel with a virtual machine as it migrates from host to host within your vSphere environment.