Re: [openstack-dev] [Neutron] [TripleO] [Ironic] Deprecating the use_namespaces option - Now's the time to speak up!

Wed, 25 Mar 2015 03:58:03 -0700

Thanks for your interest; following is a description of what Calico does in this area. Just to be clear, this is for interest and information only and I don't mean to suggest that this has any bearing on the use_namespaces deprecation discussion (especially since that change is now merged).

Calico doesn't use namespaces because it transports VM IP data between compute hosts by routing it, instead of bridging and tunnelling it. The routing between compute hosts is established in the default namespace by BGP clients (BIRD), so to connect with that the TAP interfaces from VMs need to sit in the default namespace too.

‎Then the question arises of how to provide DHCP for those TAP interfaces - unbridged, and in the default namespace. Calico does this by running dnsmasq in the default namespace, using dnsmasq's --bridge-interfaces option to treat those TAP interfaces as aliases of the dummy interface on which the DHCP context and subnet gateway IP address are provisioned.

Now, to set all that up - i.e. to provision the dummy interface; create the config files that dnsmasq needs, and update those as VMs are added or removed; launch dnsmasq; etc. -‎ is a lot of extra value, that neutron-dhcp-agent provides, and it's currently (in Icehouse and Juno) a relatively small patch on neutron-dhcp-agent to do all those things with the tweaks that Calico needs.

I hope that makes sense, and is of some interest. Please do feel free to ask any further questions. 

Regards, 
       Neil


From: Miguel Ángel Ajo
Sent: Monday, 23 March 2015 06:59
To: OpenStack Development Mailing List (not for usage questions)
Reply To: OpenStack Development Mailing List (not for usage questions)
Subject: Re: [openstack-dev] [Neutron] [TripleO] [Ironic] Deprecating the use_namespaces option - Now's the time to speak up!

Looking at project Calico, I don’t know if what they do is similar to what the people from
triple-o & ironic do with the neutron-dhcp-agent. I believe we should ask them
before deprecation.

I added their tags to the subject.

AFAIK TripleO/Ironic was patching neutron-dhcp-agent too.

For project Calico, why do you need no netns and why do you patch it? 

Kevin, thanks for pointing that out.

Best,
Miguel Ángel Ajo

On Monday, 23 de March de 2015 at 7:34, Miguel Ángel Ajo wrote:

+1 for deprecation if people don’t have use cases / good reasons to keep it, I don’t know 
     and I can’t think of any, but that doesn’t mean they don’t exist.

Miguel Ángel Ajo

On Monday, 23 de March de 2015 at 2:34, shihanzhang wrote:

+1 to deprecate this option

At 2015-03-21 02:57:09, "Assaf Muller" <[email protected]> wrote:
>Hello everyone,
>
>The use_namespaces option in the L3 and DHCP Neutron agents controls if you
>can create multiple routers and DHCP networks managed by a single L3/DHCP agent,
>or if the agent manages only a single resource.
>
>Are the setups out there *not* using the use_namespaces option? I'm curious as
>to why, and if it would be difficult to migrate such a setup to use namespaces.
>
>I'm asking because use_namespaces complicates Neutron code for what I gather
>is an option that has not been relevant for years. I'd like to deprecate the option
>for Kilo and remove it in Liberty.
>
>
>Assaf Muller, Cloud Networking Engineer
>Red Hat
>
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