Open Stack

Just to be clear, we are talking about two different cases of complexity.

"""
The biggest disconnect in the model seems to be that Neutron assumes
you want self service networking. Most of these deploys don't. Or even
more importantly, they live in an organization where that is never
going to be an option.
"""

This is referring to the complexity of the API model for Neutron. While
this is a problem that I hope to address by making things like shared
networks more useful, it's not really relevant to this particular
discussion because the model complexity does not decrease with the switch
to Linux bridge.


On Thu, Apr 16, 2015 at 5:30 PM, Tom Fifield <tom at openstack.org> wrote:

>
>
> On 17/04/15 03:09, Assaf Muller wrote:
>
>>
>>
>> ----- Original Message -----
>>
>>> "if linux bridge was a viable nova-network multi-host HA replacement,
>>> you'd
>>> be OK with this change?"
>>>
>>> I'd be much more in favor of it. yes. Though I think its a long way from
>>> being there...
>>>
>>> planet openstack has a nice set of articles on how dvr works right now,
>>>
>>
>> Thank you :)
>>
>>  and having read through, I think its going to be very difficult to
>>> implement
>>> that way with linuxbridge. It uses flow tables pretty heavily.
>>> LinuxBridge
>>> has nothing like that as far as I know.
>>>
>>
>> To be brutally honest I think that any solution that tries to implement
>> DVR
>> with Linux bridge will be shot down by the Neutron community. We're
>> already
>> struggling to maintain DVR, polish it and have it well tested. Adding more
>> complexity seems outright insane to me and I suspect that others will
>> share
>> the sentiment.
>>
>>
>>> Because of that, I would expect that as DVR matures, the LinuxBridge
>>> implementation will wither further on the vine. :/
>>>
>>> Just my 2 cents. Ops will probably need to consider the "complexity"
>>> necessary, just like the linux kernel is "complex" but in the end, the
>>> complexity is well worth it.
>>>
>>
>> That's what Neutron developers are likely to say.
>>
>
> ... and so we go around in the circle again, because:
>
> """
> The biggest disconnect in the model seems to be that Neutron assumes
> you want self service networking. Most of these deploys don't. Or even
> more importantly, they live in an organization where that is never
> going to be an option.
> """
>
> http://lists.openstack.org/pipermail/openstack-dev/2015-March/058801.html
>
>
> So, if ops don't need and/or can't use the features the additional
> complexity provides, there's no way they'll consider the complexity
> "necessary", and will keep using nova-network :)
>
>
> In addition - we kinda have part of our mission statement that has the
> words "simple to implement", so it's very rarely OK to say "just eat up the
> complexity, kthxbai".
>
>
>
>
>>
>>> To get a truly scalable NaaS, which I think is critical, you need
>>> advanced
>>> SDN and I'm not convinced LinuxBridge is advanced enough to work long
>>> term...
>>>
>>> Thanks,
>>> Kevin
>>>
>>> ________________________________________
>>> From: Tom Fifield [tom at openstack.org]
>>> Sent: Wednesday, April 15, 2015 7:09 PM
>>> To: openstack-dev at lists.openstack.org
>>> Subject: Re: [openstack-dev] [Nova][Neutron] Linuxbridge as the default
>>> in
>>> DevStack [was: Status of the nova-network to Neutron migration work]
>>>
>>> On 16/04/15 10:54, Fox, Kevin M wrote:
>>>
>>>> Yes, but.... if stuff like dvr is the only viable replacement to
>>>> nova-network in production, then learning the non representitive config
>>>> of neutron with linuxbridge might be misleading/counter productive since
>>>> ovs looks very very different.
>>>>
>>>
>>> Sure, though on the other hand, doesn't current discussion seem to
>>> indicate that OVS with DVR is not a viable replacement for nova-network
>>> multi-host HA (eg due to complexity), and this is why folks were working
>>> towards linux bridge?
>>>
>>> In essence: if linux bridge was a viable nova-network multi-host HA
>>> replacement, you'd be OK with this change?
>>>
>>>
>>>  Kevin *
>>>> *
>>>> ------------------------------------------------------------------------
>>>> *From:* Tom Fifield
>>>> *Sent:* Wednesday, April 15, 2015 5:58:43 PM
>>>> *To:* openstack-dev at lists.openstack.org
>>>> *Subject:* Re: [openstack-dev] [Nova][Neutron] Linuxbridge as the
>>>> default in DevStack [was: Status of the nova-network to Neutron
>>>> migration work]
>>>>
>>>>
>>>>
>>>> On 14/04/15 23:36, Dean Troyer wrote:
>>>>
>>>>> On Tue, Apr 14, 2015 at 7:02 AM, Miguel Angel Ajo Pelayo
>>>>> <mangelajo at redhat.com <mailto:mangelajo at redhat.com>> wrote:
>>>>>
>>>>>      Why would operators install from devstack? that’s not going to be
>>>>>      the case.
>>>>>
>>>>>
>>>>> If they do they need more help than we can give...
>>>>>
>>>>
>>>> So, ummm, there is actually a valid use case for ops on devstack: it's
>>>> part of the learning process.
>>>>
>>>> In my rounds, I've had feedback from more than a few whose first
>>>> OpenStack experience was to run up a devstack, so they could run ps
>>>> aufx, brctl, iptables, etc just to see what was going on under the
>>>> covers before moving on to something more 'proper'.
>>>>
>>>>
>>>> While acknowledging that the primary purpose and audience of devstack is
>>>> and should remain development and developers, if there is something we
>>>> can do to improve the experience for those ops first-timers that doesn't
>>>> have a huge impact on devs, it would be kinda nice.
>>>>
>>>> After all, one of the reasons this thread exists is because of problems
>>>> with that ramp up process, no?
>>>>
>>>>
>>>>
>>>>>      I believe we should have both LB & OVS well tested, if LB is a
>>>>> good
>>>>>      option for
>>>>>      some operators willing to migrate from nova, that’s great, let’s
>>>>>      make sure LB
>>>>>      is perfectly tested upstream.
>>>>>
>>>>>
>>>>> +1
>>>>>
>>>>>      But by doing such change we can’t let OVS code rot and we would be
>>>>>      neglecting
>>>>>      a big customer base which is now making use of the openvswitch
>>>>>      mechanism.
>>>>>      (may be I’m miss understanding  the scope of the change).
>>>>>
>>>>>
>>>>> Changing DevStack's default doesn't remove anything OVS-related, nor
>>>>> does it by itself remove any OVS jobs.  It gives everyone who is happy
>>>>> with nova-net (or more correctly doesn't think about it) a new default
>>>>> that changes their experience the least for when nova-net disappears.
>>>>>
>>>>> dt
>>>>>
>>>>> --
>>>>>
>>>>> Dean Troyer
>>>>> dtroyer at gmail.com <mailto:dtroyer at gmail.com>
>>>>>
>>>>>
>>>>>
>>>>> __________________________________________________________________________
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>>>>>
>>>>>
>>>>
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>>>>
>>>>
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>>>
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-- 
Kevin Benton
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