[Openstack-operators] Working of nova-network and nova-compute, basic questions

Salman Toor salman.toor at it.uu.se
Sat Oct 13 22:59:56 UTC 2012


Hi, 

Thanks for giving second try explain things :-)


Sent from my iPad

On 12 okt 2012, at 19:06, Andrew Glen-Young <andrew.glen-young at canonical.com> wrote:

> On Fri 12-10-2012 09:32 ›, Salman Toor wrote:
>> 
>> Some comments are inlined.  On Oct 12, 2012, at 5:55 AM, Matt Joyce
>> wrote:
>> 
>>> - Do I need to create a bridge on the new compute node, when I don't
>>> want to run nova-network on that node? I think bridge is only
>>> required by the nova-network? But than I get confused with how the
>>> network will work? I mean all the traffic of the VMs will go from
>>> the node running nova-network? I guess this is not correct right? 
>>> 
>>> 
>>> Depends on how your networking is set up.  But usually a bridge is
>>> created for each virtual interface of your instances.  nova-compute
>>> will do that for you.
>> 
>> So with this statement should I understand that the bridge is also
>> required/used by nova-compute… right?  In this case I thing the
>> traffic will not route through the node that runs the nova-network…. 
> 
> The bridge is required to connect the instance interfaces to the host's
> interface. Think of the bridge as a virtual switch connecting the
> instances and the host machines. It should not affect routing.
> 

Yes clear.

>>> 
>>> If all the traffic from VMs will route through the node running
>>> nova-network then should I run nova-network on each compute node as
>>> well? Or what is the correct way? 
>>> 
>>> 
>>> depends on your networking configuration.   
>> 
>> Can you please explain it a bit. I mean in a very simple scenario, 
>> 
>> node-A, controller node running nova-api, nova-network,
>> nova-scheduler, nova-cert, nova-cert, nova-objectstore, nova-volume 
>> 
>> node-B, only nova-compute 
>> 
>> Will the traffic of the booted instances on node-B will route from
>> node-A or not.
>> 
> 
> Unfortunately, it still depends... I will try clarify.
> 
> In this scenario, all floating_ip traffic will be NAT'ed via the
> nova-network host and so will be routed via this host. The fixed_ip
> traffic will route via the compute node's default gateway. The gateway
> may be the nova-network host, but not necessarily.
> 

Yes now clear.

> Hope this helps.
> 

Thanks again, 

Regards..
Salman. 


> -- 
> Regards.
> Andrew Glen-Young
> 
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