ubuntu on x86 as kvm

hello ,
I ahve insatll ubuntu on ROS x86
I can see it in the console
but I can’t give it an Ip
this is what I have :

root@(none):~# ifconfig

 ifconfig
eth0      Link encap:Ethernet  HWaddr 02:c7:18:20:03:a8  
          inet addr:10.0.0.3  Bcast:10.0.0.255  Mask:255.255.255.0
          inet6 addr: fe80::c7:18ff:fe20:3a8/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:47 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:0 (0.0 B)  TX bytes:2190 (2.1 KB)



lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:8 errors:0 dropped:0 overruns:0 frame:0
          TX packets:8 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:704 (704.0 B)  TX bytes:704 (704.0 B)

I have created a virtaul IP to the unit

  VIRTUAL-MACHINE                                 INTERFACE                                DYNAMIC-BRIDGE                                HOST-MAC-ADDRESS  VM-MAC-ADDRESS   

 0  D  ubuntu                                          tap5                                     none                                          02:68:71:66:EC:EE 02:C7:18:20:03:A8

IP of tap5 - 10.0.0.2

when I ping from the x86 to 10.0.0.2 I get replay.
but from the ubuntu when I try to ping 10.0.0.2 - I get no replay .
why ?
what have I miss?

Thanks ,