Open Stack

Yungho,

just to note: you can use more than one of vlan/gre/flat at the same time - ie your installation can have both gre and vlan.


As Lorin says, gre mode is easier to setup because it is completely decoupled from the physical layer 2 network. I think gre would be particularly useful in large installations where tenants frequently create/destroy networks on demand. But the networks are isolated from the real world and require floating ips, and so an l3-agent which might be a chokepoint or a single point of failure - I'm not sure what the l3-agent load balancing or failover options are with Grizzly. Also performance may suffer because the physical NICs TCP off-load engines never get triggered. 


With vlan mode instances can access real networks and routers without need for floating IPs.


Re,
Darragh.


>________________________________
> From: Lorin Hochstein <lorin at nimbisservices.com>
>To: yungho <yungho5054 at gmail.com> 
>Cc: "openstack-operators at lists.openstack.org" <openstack-operators at lists.openstack.org> 
>Sent: Tuesday, 3 September 2013, 4:24
>Subject: Re: [Openstack-operators] OpenStack-operators Digest, Vol 35,    Issue 1
> 
>
>
>Youngho:
>
>
>On Mon, Sep 2, 2013 at 10:51 PM, yungho <yungho5054 at gmail.com> wrote:
>
>Hello,
>>       I CentOs6.4 environment to deploy OpenStack G version, Controller Node, Network Node, Compute Node. Networks using Quantum, but is still on the Quantum network model do not know, and want to know under what circumstances the use of gre, under what circumstances the vlan mode.
>>
>>
>>
>
>
>Do you have administrative privileges on the networking switch that connects your compute hosts together? If so, I would recommend using vlan mode. You will need to configure your switch appropriately.
>
>
>If you aren't able to modify the settings on your switch, or if your nodes are not all connected to the same L2 network, then you will need to use GRE tunnels.
>
>
>I believe that GRE will work for pretty much all scenarios (since it just requires IP connectivity), but I think it introduces some overhead. However, I have no first-hand experience with it.
>
>
>Take care,
>
>
>Lorin
>-- 
>
>Lorin Hochstein
>
>Lead Architect - Cloud Services
>Nimbis Services, Inc.
>www.nimbisservices.com
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>