[libvirt] macvtap nt working on kvm

[Laine Stump]

On 12/14/2011 02:26 PM, Stefan Berger wrote:
> On 12/14/2011 07:40 AM, Amit Tewari wrote:
>>
>> Hi all,
>>
>> My test environment
>>
>> Host os=rhel6.1
>>
>> Guest os = rhel6.1
>>
>> Libvirt=0.8.7
>>
>> Kvm hypervisor
>>
>> I have made this entry in guest xml file
>>
>> <interface type='direct'>
>>
>> <source dev='eth0' mode='bridge'/>
>>
>> <model type='virtio'/>
>>
>> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' 
>> function='0x0'/>
>>
>> </interface>
>>
>> Now when I start the guest
>>
>> *#virsh start guest*
>>
>> Following macvtap0 is created on host and is shown below
>>
>> #*ip link show macvtap0*
>>
>> 51: macvtap0 at eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc 
>> mq state UNKNOWN qlen 500
>>
>>     link/ether 52:54:00:55:AE:B5brd ff:ff:ff:ff:ff:ff
>>
>> but when the guest is up and I try to perform
>>
>> **
>>
>> *# ifup eth0*
>>
>> *eth0 has same mac address as that of macvatap0 that is 
>>  52:54:00:55:AE:B5*
>>
>> **
>>
>> *due to this guest is not able to get dhcp address nor static ip 
>> address is working*.
>>
>> Please let me know how macvtap work on kvm.
>>
>
> I have tried your setup on my machine with the following host 
> configuration:
>
> # brctl show
> bridge name    bridge id        STP enabled    interfaces
> br0        8000.001a64d00016    no        eth0
> virbr0        8000.000000000000    yes
>
> If I use the configuration as you have shown it doesn't work for me, 
> either. However, if I use
>
> <source dev='br0' mode='bridge'/>
>
> then it works as expected. Do you happen to have a similar 
> configuration on the host with the interface the macvtap device wants 
> to use as 'source' being bridged?

Interesting. So you're saying that once the physical device is attached 
to a bridge, a macvtap attached to that device no longer works? That's 
useful to know :-)