[ovs-discuss] Linking multiple VM with remote OVS

Farrow, Paul pwfarr at essex.ac.uk
Wed Sep 5 10:51:36 UTC 2012

Thanks for the info, I have tried with and without floodlight to the same effect. I had thought that gre tunnels allowed layer 2 packets by forwarding ethernet frames  using IP and then stripping the IP header back to Ethernet when they reached the end of the tunnel? Do they not work in this way or is it that this will not work with OVS in this way?

Is there any other method you can think of to link them up as an alternative to the methods I have tried? Would a L2TP tunnel work?


-----Original Message-----
From: Jesse Gross [mailto:jesse at nicira.com] 
Sent: 04 September 2012 18:59
To: Farrow, Paul
Cc: discuss at openvswitch.org
Subject: Re: [ovs-discuss] Linking multiple VM with remote OVS

On Tue, Sep 4, 2012 at 9:22 AM, Farrow, Paul <pwfarr at essex.ac.uk> wrote:
> Hi,
> I have OVS setup on a VM and it seems to be up and running without 
> problems, the problem is I have several VM’s running on remote 
> machines that I want to link into the OVS. I have tried so many things 
> that I am almost giving up so would appreciate any help that people could give me.
> Here are the things I have tried:
> ---pptp vpn connection from remote VM to OVS VM and then adding the 
> vpn interfaces into the OVS
> ---gre tunnel from remote VM into the OVS VM and adding the gre 
> interface to OVS
> ---gre tunnel from remote VM but set up on OVS VM directly from OVS 
> (using
> ovs-vsctl)
> I am out of options and have tried so many variations of the things 
> above with no luck, I can ping IP’s before adding the interfaces to 
> OVS so the tunnels seem to be working OK, but after adding the 
> interfaces to OVS they don’t seem to want to do anything. I have 
> floodlight running as the controller which picks up the switch but 
> does not seem to discover any host machines. When using gre tunnels 
> ifconfig shows packets being received at the OVS VM but they don’t 
> seem to go anywhere or register anywhere else such as floodlight so 
> not sure what’s happening as the tunnel is obviously working. I am wondering if OVS is adding the interfaces correctly?
> Any advice or help would be great as it is causing me a bit of a headache.

Two things that I would look at:
 * I suspect that the Linux GRE tunnels that you created are carrying IP traffic, which would explain why you can ping but not use them with OVS since OVS operates on Ethernet frames.
 * I would try it without Floodlight.

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