VMware VMCI (Virtual Machine Communication Interface) is a high-speed interface that virtual machines (VMs) on the same host use to communicate with each other and the host kernel modules. This communication circumvents the network layer; proximity to the host's memory bus makes it faster and eliminates latency. VMCI also allows applications to work when network access is restricted or unavailable.
Integrated applications can have various components spread over multiple VMs. VMCI makes these applications work. Applications based on the VMware VMCI infrastructure -- user-level VM, host, VMware shared folders and VMware Tools component applications -- use the VMCI Sockets (VSOCK) API library. It is compatible with UDP and TCP at the interface level, and available in VMware Workstation 6.5 and newer versions.
VMware VMCI is not enabled by default in VMware Workstation or vSphere. To use the Virtual Machine Communication Interface, you will need to edit the .vmx file and may also implement custom install settings with VMware Tools.