Virtual Switch

• A virtual switch (vSwitch) is similar to a physical switch, but it is a built-in component in your hypervisor.
• How a virtual switch differs from a physical switch

  • The number of ports: one a physical switch, you have a defined number of ports. If you need more ports on it, you must upgrade the switch or replace it entirely. A virtual switch is scalable compared to its physical counterpart as you can simply just add more ports.
• The virtual switch also performs the same functions as a physical switch, with the exception: of how the MAC address table is handled.
• The virtual switch only cares about the MAC addresses of the VMs logically attached.

  • It doesn't care about everything else, since all other MACs can be sorted out after forwarding the frame to a physical switch.
• When a physical switch doesn't know the port a MAC address is associated with, it floods the frame to all the active ports.
• If the MAC address is unknown, the virtual switch will forward it to a physical switch via the uplink port and allow the physical switch to forward the frame.

  • This is how we can achieve low latency switching on a hypervisor virtual switch.