Comparing Virtual Switchs and Physical Switchs

As we get into software defined networking the lines will blur more and more but at this point normal virtual switches have not changed much over the years.

What does a vSwitch do?

  • Layer 2
    • has MAC address tables
    • forwards ethernet frames
    • supports VLAN configurations
    • able to trunk based on 802.1q VLAN tags
    • can establish port channels
  • Cannot support the following on layer 2
    • Dynamic negotiation protocols (like DTP or PAgP)
    • Cannot be connected to another vSwitch (making loops impossible and removing the need for STP)
  • vSwitches are unique in that
    • They authoritatively know the MAC addresses of all connected VM’s no need for learning
    • Does not need to perform IGMP snooping because it knows the multicast of attached vm’s


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