Date:	Tue, 12 May 2009 01:02:01 -0600
From:	Daniel Robbins <drobbins@...too.org>
To:	Cyrill Gorcunov <gorcunov@...nvz.org>
Cc:	Stephen Hemminger <shemminger@...ux-foundation.org>,
	netdev@...r.kernel.org, bridge@...ts.linux-foundation.org,
	davem@...emloft.net, xemul@...nvz.org
Subject: Re: [Bridge] [RFC 0/5] bridge - introduce via_phys_dev feature

Is this functionality useful for OpenVZ? Do people need the ability to
do this? Why/when is it necessary for me to be able to add eth0 to a
bridge remotely?

I don't quite (yet) understand the usefulness of this feature. You
would still be very limited in what you can change with the network if
you are remote, right? That's why I don't quite understand the benefit
of this feature. How are you planning to use it? When I set up my
OpenVZ systems, I like to get the overall network/bridge configuration
perfect so that I don't need to make major changes when I am remote.

Again, I am not an expert so I am asking purely for my own curiosity.
I support the idea of making networking more flexible, but I do not
see this particular step addressed by the patch as a common need. That
may be due to my own lack of understanding.

I am a big fan of OpenVZ though, so if it helps OpenVZ in some way,
I'd like to know about it :)

-Daniel

On Tue, May 12, 2009 at 12:19 AM, Cyrill Gorcunov <gorcunov@...nvz.org> wrote:
> On 5/12/09, Daniel Robbins <drobbins@...too.org> wrote:
>> Note: I am not a bridge guru but I'm interested in understanding this
>> new functionality better. What is the larger benefit of this feature?
>> Does this make it possible to configure a bridge setup on a remote
>> system without losing connectivity? I can't do many kinds of network
>> changes remotely without risking losing connectivity (ie. changing IP
>> address, messing with routing, etc. -- it would be likely that you'd
>> lose network connectivity :) ) Therefore, I don't know if this is a
>> benefit unless it is needed for a particular application. Is this
>> useful for OpenVZ in some way?
>>
>> Regards,
>>
>> Daniel
>>
> Hi Daniel,
>
> The idea was exactly you described, ie have an ability to configure
> remote system as bridge. There was an example how to use it in the
> pach (last patch in series). Say we have remote system with eth0 set
> up and running. So we may sign in into this system remotely. If we
> have to confugure bridge on such a system (that even eth0 has to be
> the bridge port) we connect to this system via eth0 then add bridge
> br0 and run it via ifconfig br0 up, turn on via_phys_dev feature and
> evetually add eth0 as a bridge port. We will have small delay in
> session until port get forwarding state but after we could continue
> work remotely on the system without reconfiguring routing table. Even
> ssh session being used during configuration will continue operate. So
> except a delay no session interrupt. I hope, need a good testing ;)
>
>> On Mon, May 11, 2009 at 5:46 AM, Cyrill Gorcunov <gorcunov@...nvz.org>
>> wrote:
>>> Hi,
>>>
>>> here is RFC for new via_phys_dev bridge feature.
>>> In short -- it allows to use some bridge port as
>>> bridge itself with already configured routing table.
>>>
>>> More details with example you may found in patches.
>>>
>>> Please review. Any (including _complains_) comments are
>>> highly appreciated!
>>>
>>> The series is on top of current -net-next-2.6
>>>
>>>        | commit ed9b58bc443a1210b5be1ded6421b17e015bf985
>>>        | Author Richard Genoud <richard.genoud@...il.com>
>>>        | Date Sat May 9 06:59:16 2009 +0000
>>>
>>> Cyrill
>>> _______________________________________________
>>> Bridge mailing list
>>> Bridge@...ts.linux-foundation.org
>>> https://lists.linux-foundation.org/mailman/listinfo/bridge
>>>
>>
>
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