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

> 
> On Aug 26, 2013, at 4:06 PM, Edgar Magana <emag...@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 <gong...@unitedstack.com>
>> Date: Monday, August 26, 2013 2:58 PM
>> To: "Kyle Mestery (kmestery)" <kmest...@cisco.com>, Aaron Rosen 
>> <aro...@nicira.com>, Armando Migliaccio <amigliac...@vmware.com>, Akihiro 
>> MOTOKI <amot...@gmail.com>, Edgar Magana <emag...@plumgrid.com>, Maru Newby 
>> <ma...@redhat.com>, Nachi Ueno <na...@nttmcl.com>, Salvatore Orlando 
>> <sorla...@nicira.com>, Sumit Naiksatam <sumit.naiksa...@bigswitch.com>, Mark 
>> McClain <mark.mccl...@dreamhost.com>, Gary Kotton <gkot...@vmware.com>, 
>> Robert Kukura <rkuk...@redhat.com>
>> Cc: OpenStack List <openstack-dev@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) 
>> <kmest...@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 <gong...@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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