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

Brian Haley brian.haley at hp.com
Wed Mar 21 14:51:44 UTC 2012


Is the PROMISC bit turned-on on the bridge?  I've seen that cause DUP-ed frames
on the Linux bridge, don't know about OVS however.

-Brian

On 03/21/2012 01:04 AM, 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 <mailto: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 <mailto: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.
>     > >
> 
> 
> 
> 
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