[openstack-dev] [neutron] DHCP Agent Scheduling for Segments

Carl Baldwin carl at ecbaldwin.net
Sun May 22 01:02:52 UTC 2016

On Fri, May 20, 2016 at 1:44 PM, Brandon Logan
<brandon.logan at rackspace.com> wrote:
> On Thu, 2016-05-19 at 14:16 -0600, Carl Baldwin wrote:
>> On Wed, May 18, 2016 at 1:36 PM, Kevin Benton <kevin at benton.pub> wrote:
>> >>I may have wrongly assumed that segments MAY have the possibility of being
>> >> l2 adjacent, even if the entire network they are in is not, which would mean
>> >> that viewing and scheduling these in the context of a segment could be
>> >> useful.
>> >
>> > Segments could be L2 adjacent, but I think it would be pretty uncommon for a
>> > DHCP agent to have access to multiple L2 adjacent segments for the same
>> > network. But even if that happens, the main use case I see for the scheduler
>> > API is taking networks off of dead agents, agents going under maintenance,
>> > or agents under heavy load. With the introduction of segments, all of those
>> > are still possible via the network-based API.
>> I think I agree with this.  Let's not change the API at all to begin
>> with.  I do think this means that the current API should work with or
>> without segments.  I'm not sure that the current approach of doing
>> scheduling for segments completely independently of scheduling for
>> networks works for this.  Does it?
> I still think it does, but we can make it work without making them
> separate.  My original plan was to keep them together, but that ended up
> causing some unclean code and also the possibility of requiring an
> interface change, which would break out-of-tree schedulers like bgp,
> that just got moved out of tree.  If I can devise an alternative to
> breaking that interface, then I'll go forward without separate
> schedulers.

I think we've got a general idea of how it should behave.  Let's see
what you come up with.


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