vmachine has two interface: vitual venet0 and "real" eth2 (via netdev_add) from machine. In machine  interface eth2 completely dissapear and in vmachine it arises like it was a real one.

Network diagram

       eth0                      eth1                      eth2
192.168.1.0/128         x.x.x.x/29          172.20.252.6/30
         |                            |                          |
---------------------------------------------------------        |
|                    machine                       |        |
---------------------------------------------------------        |
                           |                                     |
                       venet0                                 |
                192.168.1.128/32                        |
                     x.x.x.y/32                             |
                           |                                     |
---------------------------------------------------------------------------
|                         vmachine                                   |
---------------------------------------------------------------------------
default via x.x.x.z
192.168.1.0 directly via eth0
172.20.252.0/24 via 172.20.252.5

Hope this is much or less clear.
The reason i use vm for the moment is because of i don't install X on machine (i'm using mod_skypopen). Unfortunatelly i cannot test freeswitch outside of vmachine for the same reason + over 172.20.252.2 it comes a lot of calls to Asterisk (installed on machine) for the moment and i can't do a lot of test in a daytime by bypassing interface to vmachine and playing around.