[ovs-discuss] Help Connecting Switch to VMs

Derek Cormier derek.cormier at lab.ntt.co.jp
Wed Oct 6 08:23:02 UTC 2010

/(I apologize if this is a duplicate post. After replying, I didn't see 
the post on the discussion webpage and I just realized I need to cc the 
discussion's email)/

Yep, I am running VirtualBox on a Linux host. I'm not exactly sure what 
you mean by getting network to work, but if I put the virtual switch and 
one of the other VM's on an internal network, and I assign both of them 
IP addresses, then they can ping each other. The switch VM is also 
connected to the Internet via my Linux host.

Let me try to better explain what I am doing. Right now, each VM has its 
own internal network with the switch VM (to simulate an ethernet cable). 
The router VM has three virtual ports eth1, eth2, and eth3, and the 
three other VM's have only one virtual port. I would like to connect 
these individual ports into the switch's VM's ports.

I tried installing the Linux bridging support, but when I enter the 
following command,

	insmod datapath/linux-2.6/brcompat_mod.ko

... I get the following error.

                insmod: error inserting 
'datapath/linux-2.6/brcompat_mod.ko': -1 Unknown symbol in module

Thinking that it might already be loaded, I tried

	ovs-brcompatd --pidfile --detach -vANY:console:EMER unix:/usr/local/var/run/openvswitch/db.sock

... and received the following error.

         ovs-brcompatd: could not open brcompat socket.  Check 
"brcompat" kernel module.

Another issue I have been thinking about is the fact that VirtualBox 
only lets me assign four network adapters to each virtual machine. If I 
want to expand, I will need to add more ports to the switch. I think 
VirtualBox will let me add up to eight through the console, but that 
still may be too little. Do you think it is possible to have X ports on 
the virtual switch, have all the traffic go through one port, and still 
separately connect the other VM's? Keep in mind that the purpose of this 
is simulation and experimentation, so having extra redundant steps in 
between is okay.

Thank you for your help and your prompt reply!


On 10/05/2010 03:46 PM, Justin Pettit wrote:
> I assume that you're running VirtualBox on a Linux host, correct?  If so, have you gotten networking to work out of the box (i.e., no Open vSwitch)?  If not, then I'd recommend doing that first, since that will be documented on the VirtualBox site and support forums.  If you get all that working, you could then try running Open vSwitch with bridge compatibility:
> 	http://openvswitch.org/cgi-bin/gitweb.cgi?p=openvswitch;a=blob_plain;f=INSTALL.bridge;hb=HEAD
> If all that works, then we can discuss how to switch over to natively using the Open vSwitch commands, which should be pretty trivial.  In the meantime, why don't you let us know where you run into troubles?
> --Justin
> On Oct 4, 2010, at 10:57 PM, Derek Cormier wrote:
>> Hello,
>> I am trying to set up an Open vSwitch configuration where OVS is installed on a virtual machine and other virtual machines connect to it. I am using Virtual Box. Because I have only begun to study networking, this is naturally difficult for me. After reading the documentation, I still cannot figure out how to connect a port from the virtual switch to a port on another virtual machine. The switch vm has a host-only network to my machine and the other vm's are connected to the switch via an internal network (http://www.virtualbox.org/manual/ch06.html has a description of these network types).
>> I would appreciate if anyone could give me some advice without, if possible, the assumption I know a lot about networking.
>> Thank you,
>> Derek
>> _______________________________________________
>> discuss mailing list
>> discuss at openvswitch.org
>> http://openvswitch.org/mailman/listinfo/discuss_openvswitch.org

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