[Openstack] Network IP address setting in nova.conf file

Jānis Ģeņģeris janis.gengeris at gmail.com
Thu Oct 4 07:37:00 UTC 2012


Hello Ahmed,

On Thu, Oct 4, 2012 at 9:08 AM, Ahmed Al-Mehdi <ahmed at coraid.com> wrote:

> Hi Anne,
>
> Thank you for the explanation.  A few follow-up question:
>
> 1. Is the set of IP address mentioned by fixed_range distributed over all
> the Compute Nodes. E.g., a VM on Compute Node1 would get an IP address
> from this range.  Another VM instance on Compute Node2 would get an IP
> address from this same range.  Is that right?
>
I think it depends on configuration, but with standard setup as described
in docs, it's done exactly as you think.

2. Pardon my ignorance, what does POC stand for?
>
It might be Proof Of Concept , depends on context.


> 3. br100 interface can be created on a Native Ubuntu server also, not
> necessarily on VM in VirtualBox, right?


> 4. The br100 interface is only applicable to the Computer Node, not the
> Controller Node, right?
>
http://docs.openstack.org/essex/openstack-compute/admin/content/libvirt-flat-dhcp-networking.html
This image gives good illustration about the responsibilities assigned to
br100.

As I understand then br100 is interface where the VM network will be
plugged in. It makes sens of having it only on compute nodes. But you can
assign addresses from different subnets to the bridge, and make the
instances accessible from the controller node as well.


>
> 5. The command to create the network for compute VMs - "nova-manage
> network create Š." is executed on the Compute Node, right?

nova-manage works with the configured database and uses your nova.conf for
getting the db dsn. It is independent from compute nodes. It depends on
network configuration what happens later and where it's executed. I think
nova-network service is working with all the network stuff if you are not
using quantum. But I might be wrong here.




> 6. In my setup, one physical host will be the Controller Node, one
> physical host is the Compute Node, and I might add another physical host
> to be the Compute Node.  In this setup, what I the recommended setup for
> public_interface?  Or does that depend on the number of NIC ports on the
> physical host?
>
The public interface is where the floating IPs are handled. Better make it
separate, although I have red that people have managed to make compute
nodes with single interface, it might be more painful to setup.


>
> Thank you,
> Ahmed.
>
>
>
> On 10/3/12 8:26 PM, "Anne Gentle" <anne at openstack.org> wrote:
>
> >Hi Ahmed -
> >
> >I have logged a doc bug to clear up this mismatch:
> >https://bugs.launchpad.net/openstack-manuals/+bug/1061352.
> >
> >Appreciate you asking!
> >
> >Here's some explanation for each setting.
> >fixed_range - fixed block of IP addresses handed out to VMs as they're
> >provisioned. So these could be a 10.0.0.0/4 block if you want, or the
> >192... block.
> >public_interface - some say this needs to be a physical nic, but when
> >you're running a POC on a VM on a laptop in VirtualBox for example, it
> >can be br100. It's what DevStack defaults to. This setting indicates
> >the interface nova-network uses to send the floating ip traffic on the
> >correct network. So if you have nova-network on each compute node then
> >yes, it belongs on the compute node.
> >
> >The Install/deploy guide walks through Flat DHCP as the network
> >manager. If you use --network_bridge=br100 when you run the
> >nova-manage network command, nova will set up the bridge for you. This
> >example command uses 192.168.100.0/24 for the fixed range of IP
> >addresses:
> >
> http://docs.openstack.org/trunk/openstack-compute/install/apt/content/comp
> >ute-create-network.html
> >
> >Hope this helps.
> >
> >Others on the list, feel free to correct my explanations as needed!
> >Thanks,
> >Anne
> >
> >On Wed, Oct 3, 2012 at 6:46 PM, Ahmed Al-Mehdi <ahmed at coraid.com> wrote:
> >> Hello,
> >>
> >> I am following the steps in "OpenStack Install and Deploy ­ RedHat
> >>Ubuntu"
> >> (Folsom) to setup a Controller node.  The section "Configuring OpenStack
> >> Compute" (
> >>
> >>
> http://docs.openstack.org/trunk/openstack-compute/install/apt/content/com
> >>pute-minimum-configuration-settings.html
> >> )  gives a snippet of an example of the values of parameters in the
> >> nova.conf file.
> >>
> >> The document first lists some common settings in nova.conf file.  I am
> >> highlighting the following two which I am concerned about:
> >>
> >> fixed_range=192.168.100.0/24
> >> public_interface=eth0
> >>
> >> The Document right after gives the whole content of a sample (usable)
> >> nova.conf file for the Controller Node, in which the above settings are
> >>set
> >> as follows:
> >>
> >> fixed_range=10.0.0.0/24
> >> public_interface=br100
> >>
> >> I am assuming "fixed_range=192.168.100.0/24" is the correct setting.
> >> However, can someone please help as to the correct setting of
> >> "public_interface".   And the same setting value would be applicable
> >>for the
> >> Compute Node, is that right?
> >>
> >> Thank you very much in advance.
> >>
> >> Regards,
> >>
> >> Ahmed.
> >>
> >>
> >>
> >> _______________________________________________
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>
>
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-- 
--janis
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