[openstack-dev] [neutron] Are routed TAP interfaces (and DHCP for them) in scope for Neutron?

Kevin Benton blak111 at gmail.com
Tue Apr 21 08:40:05 UTC 2015

Is it compatible with overlapping IPs? i.e. Will it give two different VMs
the same IP address if the reservations are setup that way?

If not, this approach won't work for many use cases so I think you will
probably just have to write a new DHCP agent that operates in this
distributed fashion.
I haven't yet had any responses to this, so reflagging it in case it was
just missed in the helter skelter of activity that is the openstack-dev
mailing list...

On the other hand, if I need to describe more clearly what I'm on about,
please don't be afraid to say that!

Any comments and steer would be appreciated, even if they're more of a high
level gut feel, than an exhaustive treatment.


On 16/04/15 15:12, Neil Jerram wrote:

> I have a Neutron DHCP agent patch whose purpose is to launch dnsmasq
> with options such that it works (=> provides DHCP service) for TAP
> interfaces that are _not_ bridged to the DHCP interface (ns-XXX).  For
> the sake of being concrete, this involves:
> - creating the ns-XXX interface as a dummy, instead of as a veth pair
> - launching dnsmasq with --bind-dynamic --listen=ns-XXX --listen=tap*
> --bridge-interface=ns-XXX,tap*
> - not running in a separate namespace
> - running the DHCP agent on every compute host, instead of only on the
> network node
> - using the relevant subnet's gateway IP on the ns-XXX interface (on
> every host), instead of allocating a different IP for each ns-XXX
> interface.
> I proposed a spec for this in the Kilo cycle [1], but it didn't get
> enough traction, and I'm now wondering what to do with this
> work/function.  Specifically, whether to look again at integrating it
> into Neutron during the Liberty cycle, or whether to maintain an
> independent DHCP agent for my project outside the upstream Neutron tree.
>   I would very much appreciate any comments or advice on this.
> For answering that last question, I suspect the biggest factor is
> whether routed TAP interfaces - i.e. forms of networking implementation
> that rely on routing data between VMs instead of bridging it - is in
> scope for Neutron, at all.  If it is, I understand that there could be a
> lot more detail to work on, such as how it meshes with other Neutron
> features such as DVR and the IPAM work, and that it might end up being
> quite different from the blueprint linked below.  But it would be good
> to know whether this would ultimately be in scope and of interest for
> Neutron at all.
> Please do let me now what you think.
> Many thanks,
>      Neil
> [1] https://blueprints.launchpad.net/neutron/+spec/dhcp-for-routed-ifs

OpenStack Development Mailing List (not for usage questions)
Unsubscribe: OpenStack-dev-request at lists.openstack.org?subject:unsubscribe
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstack.org/pipermail/openstack-dev/attachments/20150421/6e0d9325/attachment.html>

More information about the OpenStack-dev mailing list