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On Aug 26, 2013, at 6:14 PM, Maru Newby <marun at redhat.com> wrote:

> 
> On Aug 26, 2013, at 4:06 PM, Edgar Magana <emagana at plumgrid.com> wrote:
> 
>> Hi Developers,
>> 
>> Let me explain my point of view on this topic and please share your thoughts in order to merge this new feature ASAP.
>> 
>> My understanding is that multi-host is nova-network HA  and we are implementing this bp https://blueprints.launchpad.net/neutron/+spec/quantum-multihost for the same reason.
>> So, If in neutron configuration admin enables multi-host:
>> etc/dhcp_agent.ini
>> 
>> # Support multi host networks
>> # enable_multihost = False
>> 
>> Why do tenants needs to be aware of this? They should just create networks in the way they normally do and not by adding the "multihost" extension.
> 
> I was pretty confused until I looked at the nova-network HA doc [1].  The proposed design would seem to emulate nova-network's multi-host HA option, where it was necessary to both run nova-network on every compute node and create a network explicitly as multi-host.  I'm not sure why nova-network was implemented in this way, since it would appear that multi-host is basically all-or-nothing.  Once nova-network services are running on every compute node, what does it mean to create a network that is not multi-host?

Just to add a little background to the nova-network multi-host: The fact that the multi_host flag is stored per-network as opposed to a configuration was an implementation detail. While in theory this would support configurations where some networks are multi_host and other ones are not, I am not aware of any deployments where both are used together.

That said, If there is potential value in offering both, it seems like it should be under the control of the deployer not the user. In other words the deployer should be able to set the default network type and enforce whether setting the type is exposed to the user at all.

Also, one final point. In my mind, multi-host is strictly better than single host, if I were to redesign nova-network today, I would get rid of the single host mode completely.

Vish

> 
> So, to Edgar's question - is there a reason other than 'be like nova-network' for requiring neutron multi-host to be configured per-network?
> 
> 
> m.
> 
> 1: http://docs.openstack.org/trunk/openstack-compute/admin/content/existing-ha-networking-options.html
> 
> 
>> I could be totally wrong and crazy, so please provide some feedback.
>> 
>> Thanks,
>> 
>> Edgar
>> 
>> 
>> From: Yongsheng Gong <gongysh at unitedstack.com>
>> Date: Monday, August 26, 2013 2:58 PM
>> To: "Kyle Mestery (kmestery)" <kmestery at cisco.com>, Aaron Rosen <arosen at nicira.com>, Armando Migliaccio <amigliaccio at vmware.com>, Akihiro MOTOKI <amotoki at gmail.com>, Edgar Magana <emagana at plumgrid.com>, Maru Newby <marun at redhat.com>, Nachi Ueno <nachi at nttmcl.com>, Salvatore Orlando <sorlando at nicira.com>, Sumit Naiksatam <sumit.naiksatam at bigswitch.com>, Mark McClain <mark.mcclain at dreamhost.com>, Gary Kotton <gkotton at vmware.com>, Robert Kukura <rkukura at redhat.com>
>> Cc: OpenStack List <openstack-dev at lists.openstack.org>
>> Subject: Re: About multihost patch review
>> 
>> Hi,
>> Edgar Magana has commented to say:
>> 'This is the part that for me is confusing and I will need some clarification from the community. Do we expect to have the multi-host feature as an extension or something that will natural work as long as the deployment include more than one Network Node. In my opinion, Neutron deployments with more than one Network Node by default should call DHCP agents in all those nodes without the need to use an extension. If the community has decided to do this by extensions, then I am fine' at
>> https://review.openstack.org/#/c/37919/11/neutron/extensions/multihostnetwork.py
>> 
>> I have commented back, what is your opinion about it?
>> 
>> Regards,
>> Yong Sheng Gong
>> 
>> 
>> On Fri, Aug 16, 2013 at 9:28 PM, Kyle Mestery (kmestery) <kmestery at cisco.com> wrote:
>>> Hi Yong:
>>> 
>>> I'll review this and try it out today.
>>> 
>>> Thanks,
>>> Kyle
>>> 
>>> On Aug 15, 2013, at 10:01 PM, Yongsheng Gong <gongysh at unitedstack.com> wrote:
>>> 
>>>> The multihost patch is there for a long long time, can someone help to review?
>>>> https://review.openstack.org/#/c/37919/
>>> 
>> 
> 
> 
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