vSwitch

vSwitch is a software-based virtual network switch that runs on a hypervisor and connects virtual machines to each other and to physical networks. It operates at the data link layer and forwards frames according to MAC addresses, VLAN tags, and policies defined within the virtualization platform. A vSwitch typically provides port groups or network segments to which VMs connect, and one or more uplink NICs that connect to the external network.

Key features include VLAN tagging (802.1Q) to segment traffic, NIC teaming for redundancy and throughput, and security policies such as promiscuous mode, forged transmits, and MAC address changes. It may implement traffic shaping and bandwidth controls and supports features like private VLANs or port-based access control depending on the platform.

Two common implementations in VMware: standard vSwitch (vSS), which is configured per host, and distributed switch (vDS), which spans multiple hosts and is administered from vCenter. In Microsoft Hyper-V, the equivalent is the Hyper-V Virtual Switch, with External, Internal, and Private types. Open vSwitch is an open-source virtual switch used in Linux environments and cloud platforms, offering support for multiple hypervisors and network virtualization features.

vSwitches differ from physical switches in that they are software components within a hypervisor; they do not require physical presence to forward traffic but still rely on physical NICs for external connectivity. They enable virtual networking, microsegmentation, and flexible network topology in virtual environments.