[libvirt] FW: macvtap not working on rhel 6.1 x86 machine

Amit Tewari Amit.Tewari at nechclst.in
Thu Dec 15 10:24:52 UTC 2011


i want the kvm guest machine to connect to network using macvtap..
I tried this vepa mode it is also not working.

My test environment

Host os=rhel6.1

Guest os = rhel6.1


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'/>



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.

-----Original Message-----
From: Gerhard Stenzel [mailto:gstenzel at linux.vnet.ibm.com] 
Sent: Thursday, December 15, 2011 3:47 PM
To: Amit Tewari
Cc: libvir-list at redhat.com
Subject: Re: [libvirt] FW: macvtap not working on rhel 6.1 x86 machine

On Thu, 2011-12-15 at 15:20 +0530, Amit Tewari wrote:
> Hi all,
> My test environment
> Host os=rhel6.1 x86 machine
> Guest os = rhel6.1
> Libvirt=0.8.7
> Kvm hypervisor

maybe it would help if you try to explain first, what you are trying to
achieve, what your setup looks like (including your DHCP setup and
switch infrastructure).

Here (http://libvirt.org/formatdomain.html) you will find the following
xml sample, which works: 
    <interface type='direct'>
      <source dev='eth0' mode='vepa'/>

This will connect your VM directly to the same network as eth0. Please
be aware that, depending on your switch configuration (supports hair pin
mode or not), your host might not be able to talk to your VM and vice

Best regards, 

Gerhard Stenzel, 
IBM Deutschland Research & Development GmbH
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Geschäftsführung: Dirk Wittkopp
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