[ovs-discuss] Same mac address of br0 and eth0

[Ben Pfaff]

The evidence points to a configuration error, since plenty of other
users do not see duplicate packets in similar situations.  Again I
suggest that you read REPORTING-BUGS and provide the information
suggested there.

On Wed, Mar 21, 2012 at 01:04:20PM +0800, Jingfei Hu wrote:
> Hi, Ben,
> In the last few days, I have spent my spare time on figuring out the reason
> of ping DUP problem. Here is my result:
> The network setting including netmask\default gateway etc. contains no
> error. Following is the ip address setting and routing table of the host
> and the guest:
> --------------------------------------------------------------
> Host:
> IP address:
> br0: 192.168.1.27 netmask 255.255.255.0
> Routing table:
> Destination     Gateway         Genmask         Flags Metric Ref    Use
> Iface
> 0.0.0.0         192.168.1.1     0.0.0.0         UG    0      0        0 br0
> 192.168.1.0     0.0.0.0         255.255.255.0   U     0      0        0 br0
> 
> Guest:
> IP address:
> eth0: 192.168.1.26 netmask 255.255.255.0
> Routing table:
> Destination     Gateway         Genmask         Flags Metric Ref    Use
> Iface
> 0.0.0.0         192.168.1.1     0.0.0.0         UG    0      0        0 eth0
> 169.254.0.0(link-local)     0.0.0.0         255.255.0.0     U     1000   0
>        0 eth0
> 192.168.1.0     0.0.0.0         255.255.255.0   U     1      0        0 eth0
> --------------------------------------------------------------
> The ping DUP problem is still there.
> Then in another machine, the same steps are executed with same host os and
> same guest os, except that br0 is created using bridge-utils package, not
> ovs-vsctl. When ping from the guest, the DUP problem has gone. So it seems
> that the bridge created by ovs-vsctl is different than the bridge created
> by bridge-utils package. Is that correct to say this problem is related to
> ovs?
> 
> Cheers,
> 
> Hu Jingfei
> 
> 3/19 Ben Pfaff <blp at nicira.com>
> 
> > I don't see how br0 and eth0 having the same MAC address would cause the
> > behavior that you mention.  I would suggest following a conventional
> > troubleshooting procedure instead of making this assumption.
> >
> > If you want us to help with that troubleshooting then you can start from
> > the suggestions in REPORTING-BUGS.
> >
> > On Mon, Mar 19, 2012 at 10:12:17AM +0800, Jingfei Hu wrote:
> > > Thanks, Ben,
> > > But there is a problem here. The following commands have not changed:
> > > ------------------------------------
> > > sudo ovs-vsctl add-br br0
> > > sudo ovs-vsctl set bridge br0 datapath_type=netdev
> > > sudo ovs-vsctl add-port br0 eth0
> > > sudo ovs-vsctl add-port br0 tap0
> > > ------------------------------------
> > > The tap0 interface is created using OpenVPN utility with following
> > command:
> > > ------------------------------------
> > > sudo openvpn --mktun --dev tap0
> > > ------------------------------------
> > > Then I have created a VM using VirtualBox-4.1 and made the VM use the
> > > Bridged Adapter tap0. IP address settings are:
> > > ------------------------------------
> > > In my host:
> > > sudo ifconfig br0 192.168.1.24 netmask 255.255.255.0
> > > eth0 and tap0 got no ip address assigned
> > > In the guest, i.e. VM:
> > > sudo ifconfig eth0 192.168.1.26 netmask 255.255.255.0
> > > ------------------------------------
> > > After that, my guest is able to reach the outside network, and the
> > machine
> > > which resides in the same LAN, says it's ip address is 192.168.1.14,
> > could
> > > also found my guest. The PROBLEM is:
> > > when I ping the 192.168.1.14 from my guest, the ICMP reply is always
> > > duplicated. I guess the cause is because the br0 has the same mac address
> > > with eth0, but don't know how to solve it.
> > > Any ideas will be appreciated. Sorry for the question in question, I
> > should
> > > ask it in one post.
> > >
> > > Cheers,
> > > Hu Jingfei
> > >
> > >
> > > 2012/3/18 Ben Pfaff <blp at nicira.com>
> > >
> > > > On Sun, Mar 18, 2012 at 10:46:36PM +0800, Jingfei Hu wrote:
> > > > > I have installed OVS userspace program on Ubuntu Oneiric according to
> > > > > INSTALL.Linux. Then I have added a bridge using following commands:
> > > > >
> > > > > sudo ovs-vsctl add-br br0
> > > > > sudo ovs-vsctl set bridge br0 datapath_type=netdev
> > > > > sudo ovs-vsctl add-port br0 eth0
> > > > > sudo ovs-vsctl add-port br0 tap0
> > > > >
> > > > > Then I setup the bridge br0 as follows:
> > > > > sudo ifconfig br0 192.168.1.24 netmask 255.255.255.0
> > > > > After that, I check it with command ifconfig -a, finding that the
> > mac br0
> > > > > and eth0 have the same mac.
> > > > >
> > > > > Is it normal?
> > > >
> > > > Yes.
> > > >
> >