4 Replies Latest reply on Dec 10, 2015 12:27 AM by i1wan

    Connection between VM/VxLAN

    smcanuff Lurker

      I am having a connection problem, which I would like to know if anyone has this problem. I have two VM that is on the same logical switch, when I have the VM on the same host, I can send traffic between the VM, however when I move the VM to different host, I am unable to send traffic between the VM. I am running NSX 6.2, one DLR and one universal transport zone.

        • 1. Re: Connection between VM/VxLAN
          Richard__R Enthusiast

          Have you ruled out the chances of an MTU problem on the VXLAN transport network? If you haven't already then ping between the source and destination VTEPs as follows

          ping ++netstack=vxlan -d -s 1572 <dest VTEP IP>

          • 2. Re: Connection between VM/VxLAN
            smcanuff Lurker

            Should this ping take place on the host? MTU are all 1600.

            • 3. Re: Connection between VM/VxLAN
              Richard__R Enthusiast

              Sorry yes you can start by running that one between two hosts  as a quick check before diving deeper.

              • 4. Re: Connection between VM/VxLAN
                i1wan Novice

                You need to do the ping from the one ESXi Host where you have one VM hosted towards the other ESXi Host where the other (destination) VM is hosted on.


                You start with logging into SSH to both ESXi hosts and issue the command (like Richard__R proposed):


                ping ++netstack=vxlan -d -s 1572 <dest VTEP IP>

                If this ping DOES go trough (both sides) you at least know that your underlying infrastructure in terms of multicast (if you do not use the controller)  / MTU is ok.

                If the ping does NOT go trough you can try:

                ping ++netstack=vxlan -d -s 1472 <dest VTEP IP>

                Then you know something is up with the MTU not being 1600 end-to-end.

                Other things that I would try is well is rebooting (or turn off and on again) both VM's that you are trying to ping to and from.

                I have experienced problems before as well that VM's on the same Logical Switch and on different hosts could not ping eachother and my "solve" was rebooting the VM's.

                If your VM's have two NIC's with two default gateways configured this can also be a problem.

                You need to disable the NIC that you are not using in the OS by bringing it down, and also uncheck it as being "connected" in vCenter Server.

                Do this just for testing purpose and then you can see where you go from there...