[ovs-discuss] General Question from Open vSwitch Beginner

Hugo hugolin615 at gmail.com
Thu Mar 17 13:45:13 PDT 2011


Hi, I make my experiment 1 works, however in a different way.

I set up the eth0 into NULL directly. But it is still not working.
I find that it is due to my network or system configuration. If I manually
ifconfig eth0 down and then ifconfig eth0 up, I can not access the internet.
So I change the network here to make the machine dhcp to get ip address.
Then after I set eth0 to NULL, I dhclient br0 and then I can access the
internet now.

I will continue to my second experiment.

Thanks

On Thu, Mar 17, 2011 at 9:29 AM, Ben Pfaff <blp at nicira.com> wrote:

> 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.
> > >
>
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