I have an ESXi 5.1 host that has an ESXi 5.1 VM. On the inner ESXi is an XP VM. The XP VM cannot communicate with the world outside of the inner ESXi. It can ping the inner ESXi. My desktop (Windows 7) can ping and attach via a VSphere Client to the inner ESXi. I cannot ping the XP VM. It cannot ping me. We all are on the 192.168.1.x subnet.