I've encountered an issue in my envioronment using internal network. I've got two vms connected to the internal network. One of the vms has linux bridge running. This bridge has vms internal network interface connected and interface of linux namespace connected. Both second vm and namespace Have addresses from same subnet. When I send ping either from namespace to vm or vice versa, arp requests are being forwarded via internal network but replays dont. I see that vm or namespace are replaying on tcpdump but The replays are not forwarded via intnet . Can someone explain how internal network's vswitch works ? I attach the environment sketch. enter image description here

PS. This happens on Both linux nad Windows hosts. I've got firewall stopped on Both guest oses.

Thank you in advance, Wojtek

  • It is unclear what you want to achieve ultimately. – Biswapriyo Oct 29 at 10:44
  • I want to achieve connection between namespace and vm a. When pinging vma from namespace, arp request is forwarded to vm a, vm a sends replay but performing tcpdump on vm b enp0s8 or br0 interface I can't see any replay packet. This is why i suspect virtualbox internal network malfunction. – wojtekM Oct 29 at 11:23
  • The vbox vswitch is a bridge, just like br0 in your Linux machine. It works exactly like an unmanaged layer 2 switch (e.g. your everyday dumb 8 port switch). – Andy Oct 29 at 20:14
  • Okay so it should learn mac addresses (for example of namespace's arp request) But it is not possible i think to inspect this "virtual switch" fdb... – wojtekM Oct 30 at 9:43

Okay, I am now quite convinced that it might be Centos issue. I found a post where a user had similar issue. He wrote that after upgradinf kernel from 3.10 to 4.4 a linux bridge started forwarding arp responses. Anyone had similar issues ?

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