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How vm's traffic pass to physical switch

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  • How vm's traffic pass to physical switch

    Hi dear
    if I have three port groups that with thier subnets, and I don't use vlan Id for them,
    Now physical switch how see this traffics and how vsphere send vm's traffic to physical switch and how switch pass traffic to VMs from external network ?

    Very thanks for your helps,

  • #2
    Your port groups reside within 1 or more vSwitches, each vSwitch will have 1 or more associated physical NIC ports used as uplinks (the interface between the virtual world and physical world).

    If you understand switching, you should understand how virtual networking functions.
    VCP2 / VCP3 / VCP4 / VCP 5 / VCAP-DCA4 / VCI / vExpert 2010-2012


    • #3
      Hi dear,
      Thanks for your help,
      but , I want know:
      With a vSwitch and three port groups that have theirs subnet , if for any port groups don't determine vlan Id, if vm's want connect to external network, how their packets out from vSwitch ?

      very thanks,


      • #4
        Without VLANs, but with 3 subnets, you're running 3 L3 networks over the same L2 network - no different from if you did that in the physical world.

        VMs on the same port group (subnet) will talk to one another and devices on the physical network on the same subnet without the need of a router, to talk across subnets they will send to their configured router.

        How do packets get from the vSwitch to the physical network and back? Through the physical NICs, which are the uplink ports of a vSwitch.

        Learn more here:
        VCP2 / VCP3 / VCP4 / VCP 5 / VCAP-DCA4 / VCI / vExpert 2010-2012


        • #5
          Ok ,
          I see your link but I don't find my question in it,
          Dear for final question :
          when a packet from a VM send to uplink for send to physical switch, I want know how physical switch treat with packet and it what record in mac table of switch?


          • #6
            Does this help ?
            Tom Jones
            MCT, MCSE (2000:Security & 2003), MCSA:Security & Messaging, MCDBA, MCDST, MCITP(EA, EMA, SA, EDA, ES, CS), MCTS, MCP, Sec+
            PhD, MSc, FIAP, MIITT
            IT Trainer / Consultant
            Ossian Ltd

            ** Remember to give credit where credit is due and leave reputation points where appropriate **


            • #7
              Each VM will have 1 or more NICs, each connected to a port group within your vSwitch.

              Each of those NICs has it's own unique MAC address.

              Those addresses are set as the source address of the packet as it leaves the ESXi host through physical NIC/uplink, so the physical switch port will see many source MAC addresses - which again is no different to when physical switch is uplinked to another physical switch.
              VCP2 / VCP3 / VCP4 / VCP 5 / VCAP-DCA4 / VCI / vExpert 2010-2012


              • #8
                Hi dears,
                very thanks for your helps,