[Openstack-operators] Accessing internal networks from a VM

Lorin Hochstein lorin at nimbisservices.com
Thu Dec 5 18:10:13 UTC 2013

Hi Sam:

I believe this is doable if you're using Neutron for networking. You would
need to set up two Neutron "external" networks, one that contains the
subnet with external, routable IPs, and the other that contains the subnet
that is routable to your internal services.

Last time I checked, Neutron only supported one external network per
network controller (this is a limit of the L3 agent implementation). This
means you'll have to set up two separate network controller nodes with L3
agents, one that has a network connection to your external network, and the
other that had the network connection to your internal network.

It's up to you whether you want your OpenStack instances to connect
directly to these networks, or if you want to use internal OpenStack
networks and use floating IPs. Either way, when you boot your instances,
you need to specify that you want the instances to be connected to both
networks. Your instances will then come up with two virtual NICs.

Hope this helps. Good luck!

Take care,


On Thu, Dec 5, 2013 at 10:02 AM, Samuel Winchenbach <swinchen at gmail.com>wrote:

> Hi everyone,
> Is there a good way to have VMs access both an external and internal
> network?   We would like set up several VMs that have external, route-able
> IPs but also have access to our internal network for some of internal
> services (e.g. NFS).
> Any tips would be welcome!
> Thanks,
> Sam
> _______________________________________________
> OpenStack-operators mailing list
> OpenStack-operators at lists.openstack.org
> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-operators

Lorin Hochstein
Lead Architect - Cloud Services
Nimbis Services, Inc.
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