[ovs-discuss] General Question from Open vSwitch Beginner

Ben Pfaff blp at nicira.com
Thu Mar 17 14:29:03 UTC 2011


You have to remove the IP address from eth0, e.g. "ifconfig eth0 0.0.0.0".

On Thu, Mar 17, 2011 at 12:23:25AM -0500, Hugo wrote:
> Hi,
> 
> I redo the experiment 1 based on your suggestion. My eth0 has an IP address
> assigned to it. After I attach eth0 to the bridge, i.e br0, the MAC of br0
> and eth0 become the same. And I try to assign the same IP address or
> different IP address to br0, in both situation,  eth0 still has its IP
> address and in the "up" status. Even I try to use ifconfig to shutdown eth0
> and reboot eth0, it still has its own IP address. Of course, I could not
> access the network in this situation. Is there anything wrong on this
> setup?
> 
> Best,
> Hugo
> 
> On Wed, Mar 16, 2011 at 6:37 PM, Ben Pfaff <blp at nicira.com> wrote:
> 
> > On Wed, Mar 16, 2011 at 06:33:42PM -0500, Hugo wrote:
> > > Experiment 1.
> > > There is no VM in this experiment. I just install OVS in a debian host
> > > machine. I follow the instruction in INSTALL.Linux. And I start up
> > > "ovsdb-server" and "ovs-vswitchd" by executing the commands from
> > > INSTALL.Linux too. There is no problem at this point. Then I run
> > >
> > > % ovs-vsctl add-br br0
> > > % ovs-vsctl add-port br0 eth0
> > >
> > > eth0 is the only physical NIC in my host machine, it has the IP address
> > > assigned, I can access the network from this NIC before. After doing
> > this,
> > > my host machine will not be able to access the network. My understanding
> > is
> > > that this actually emulating the real situation that connecting port from
> > a
> > > physical switch to a physical NIC by a ethernet cable. Then of course,
> > the
> > > machine could not access the internet.
> > > However, in the real situation, usually a port from a physical switch can
> > be
> > > connected to the network through a ethernet cable. And we can go into the
> > > switch's console to configure the physical switch (such as setup DNS) to
> > > make it access to the network. I just wondering how can I configure the
> > Open
> > > vSwitch in any similar way to let it be able to access network?
> >
> > You can put your IP address on the br0 interface, e.g.:
> >        ifconfig br0 192.168.0.123
> > This is the same as what you would have to do with the Linux bridge.
> >
> > > Experiment 2
> > > I install a VM in a VirtualBox. Instead of NAT, I choose the Network
> > adapter
> > > as "Host-Only", and in this way, the Guest VM will connect through a
> > > interface named "vboxnet0". This "vboxnet0" is network interface from
> > > VirtualBox. It is visible from ifconfig in my HOST debian machine. I
> > still
> > > start up "ovsdb-server" and "ovs-vswitchd" by executing the commands from
> > > INSTALL.Linux. I run (of course, I delete eth0 from br0)
> > >
> > > % ovs-vsctl add-br br0
> > > % ovs-vsctl add-port br0 vboxnet0
> > >
> > > After doing this, the Virtual VM is not able to access the network. I am
> > > just wondering what should I do in order to make the VM to be able to
> > access
> > > the network. Do I have to do some configuration in Guest VM as well as
> > Open
> > > vSwitch? I think these two experiments are simple, I hope from your
> > answer,
> > > I can better understand how Open vSwitch works and then I can try
> > scenarioes
> > > in cookbook.
> >
> > An Ethernet switch with only one port is not very useful.  If you add
> > a physical port to the switch, with "ovs-vsctl add-port br0 eth0",
> > then the VM will be able to access the network through that physical
> > port.
> >



More information about the discuss mailing list