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Re: Decoupling of Network and Compute services for the new Network Service design


definitely not fine to use dhcp in all cases.

On Thu, Feb 24, 2011 at 3:28 AM, Dan Mihai Dumitriu <dmd17@xxxxxxxxxxx>wrote:

> If we can dynamically plug (and presumably unplug) a vNIC into a
> vPort, and assign the IP at that time, does that imply that we cannot
> use the IP injection into the VM image?  Is it fine to use DHCP or RA
> in all cases?
> On Wed, Feb 23, 2011 at 22:29, Ishimoto, Ryu <ryu@xxxxxxxxxxx> wrote:
> >
> > Hi everyone,
> > I have been following the discussion regarding the new 'pluggable'
> network
> > service design, and wanted to drop in my 2 cents ;-)
> > Looking at the current implementation of Nova, there seems to be a very
> > strong coupling between compute and network services.  That is, tasks
> that
> > are done by the network service are executed at the time of VM
> > instantiation, making the compute code dependent on the network service,
> and
> > vice versa.  This dependency seems undesirable to me as it adds
> restrictions
> > to implementing 'pluggable' network services, which can vary, with many
> ways
> > to implement them.
> > Would anyone be opposed to completely separating out the network service
> > logic from compute?  I don't think it's too difficult to accomplish this,
> > but to do so, it will require that the network service tasks, such as IP
> > allocation, be executed by the user prior to instantiating the VM.
> > In the new network design(from what I've read up so far), there are
> concepts
> > of vNICs, and vPorts, where vNICs are network interfaces that are
> associated
> > with the VMs, and vPorts are logical ports that vNICs are plugged into
> for
> > network connectivity.  If we are to decouple network and compute
> services,
> > the steps required for FlatManager networking service would look
> something
> > like:
> > 1. Create ports for a network.  Each port is associated with an IP
> address
> > in this particular case, since it's an IP-based network.
> > 2. Create a vNIC
> > 3. Plug a vNIC into an avaiable vPort.  In this case it just means
> mapping
> > this vNIC to an unused IP address.
> > 4. Start a VM with this vNIC.  vNIC is already mapped to an IP address,
> so
> > compute does not have to ask the network service to do any IP allocation.
> > In this simple example, by removing the request for IP allocation from
> > compute, the network service is no longer needed during the VM
> > instantiation.  While it may require more steps for the network setup in
> > more complex cases, it would still hold true that, once the vNIC and
> vPort
> > are mapped, compute service would not require any network service during
> the
> > VM instantiation.
> > IF there is still a need for the compute to access the network service,
> > there is another way.  Currently, the setup of the network
> > environment(bridge, vlan, etc) is all done by the compute service. With
> the
> > new network model, these tasks should either be separated out into a
> > standalone service('network agent') or at least be separated out into
> > modules with generic APIs that the network plugin providers can
> implement.
> >  By doing so, and if we can agree on a rule that the compute service must
> > always go through the network agent to access the network service, we can
> > still achieve the separation of compute from network services.   Network
> > agents should have full access to the network service as they are both
> > implemented by the same plugin provider.  Compute would not be aware of
> the
> > network agent accessing the network service.
> > With this design, the network service is only tied to the network REST
> > and the network agent, both of which are implemented by the plugin
> > providers.  This would allow them to implement their network service
> without
> > worrying about the details of the compute service.
> > Please let me know if all this made any sense. :-)  Would love to get
> some
> > feedbacks.
> > Regards,
> > Ryu Ishimoto
> >
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> >
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