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I am trying to connect a number of VMs using Open vSwitch. The VMs are on two separate physical boxes. Here is what I did:

  1. Created two tap devices on one physical host
    sudo ip tuntap add mode tap tap0 and same for tap1
  2. Bring them up
    sudo ip link set tap0 up
  3. Add them as ports to Open vSwitch
    (br0 was created as a OVS bridge previously) sudo ovs-vsctl add-port br0 tap0 tag=1

Now I booted the VMs (using VirtualBox) and assigned addresses and Now when I try to ping one VM from another, I get the error Connect: network is unreachable. Since both VMs are connected to the switch on the same VLAN, I expect to be able to ping one from another. What is going wrong here?

Update I found that the routing table goes blank after some time and that is when ping fails. If I add a static route, it works for some time and fails again. Any idea why does the routing table is erased?

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up vote 0 down vote accepted

This turned out to be a problem with DHCP configuration on the guests. Once I removed that, it worked fine.

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