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Flat network no dhcp

asked 2013-12-04 10:28:42 -0500

trumpjk gravatar image

updated 2013-12-16 12:33:10 -0500

smaffulli gravatar image

I would like to configure my openstack to use IP's from the same network as my physical server. I do not want to use dhcp or floating IP's. Basically I am testing openstack in hopes I can replace vmware esx servers. I installed an all-in-one RDO implementation on a single server.

Is there a guide that shows how to setup such a network config? I have not been able to successfully create a VM and have it attach to a flat network.

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Are you using KVM or EXSi for virtualization?

Cristi Falcas gravatar imageCristi Falcas ( 2013-12-11 02:17:49 -0500 )edit

I do not want to interact with vmwre at all. I want to use openstack to replace vmware. I installed an all-in-one rdo implementation on a single server.

trumpjk gravatar imagetrumpjk ( 2013-12-16 12:25:50 -0500 )edit

@trumpjk: a comment below by @antonnoble seem to have a useful hint: You can specify your flat network via your nova.conf

smaffulli gravatar imagesmaffulli ( 2013-12-16 12:36:00 -0500 )edit

I have tried this and when I create a VM it fails. I have tried creating the vm through both the web interface and command line. I am guessing I am missing a step somewhere.

trumpjk gravatar imagetrumpjk ( 2013-12-16 12:39:29 -0500 )edit

What is you error? Check compute log and nova log.

Cristi Falcas gravatar imageCristi Falcas ( 2013-12-17 04:27:28 -0500 )edit

2 answers

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answered 2013-12-10 13:20:56 -0500

Cristi Falcas gravatar image

updated 2013-12-17 04:31:43 -0500

I'm doing exactly this: flat network, dhcp disabled.

For automatically configuration (IP, hostname, dns servers, etc) I use the config drive option and a custom script that will read it. You can also use cloud-init for this, but I had problems with that (the reason for the custom script)

For the configuration, if you use as compute nodes the esx servers, you will have to use nova network.

For kvm you can use either neutron or nova network.


If you configure manually the instances with the correct networking, you should be enough.


For KVM with neutron and ovs I use this configuration:


## config drive
force_config_drive = True
config_drive_cdrom = True
flat_injected = True

## neutron config

plugin.ini (where you define physnet used when creating the networks)

tenant_network_type = gre
enable_tunneling = True
tunnel_id_ranges = 1:1000
network_vlan_ranges = physnet:1:1
bridge_mappings = physnet:br-ex
local_ip = LOCAL_IP
tunnel_types = gre

How to create the network (this is considering that the outside IPs are in the range

neutron net-create NET_NAME --shared --provider:network_type flat --provider:physical_network physnet

neutron subnet-create NET_NAME --name default_subnet --gateway --host-route destination=,nexthop= --allocation-pool start=,end= --dns_nameservers list=true --disable-dhcp

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Is there documentation on how to do this, i.e. which files do I need to edit? THe point I am at now is I created a flat network and when I create a vm via command line and pass an IP address the VM fails to create and errors.

trumpjk gravatar imagetrumpjk ( 2013-12-10 14:18:21 -0500 )edit

Doesn't really sound as much a networking problem, but rather a problem connecting to your esxi nodes. You have to specify the vmwareapi driver in your nova-compute.conf file. And the proper vmware parameters in your nova.conf file. You can specify your flat network via your nova.conf

antonnoble gravatar imageantonnoble ( 2013-12-11 01:27:38 -0500 )edit

I haven't tried using a flat network with dhcp off and on the same network as physical node. Keep in mind you can't use neutron with esxi and with vsphere you have to have nvp/Nsx plugin and Nsx controller

antonnoble gravatar imageantonnoble ( 2013-12-11 01:31:14 -0500 )edit

Let me clarify. I am not interacting with esx servers at all. I installed an all-in-one rdo implementation on a single server. I am looking at openstack as a replacement for esx servers.

trumpjk gravatar imagetrumpjk ( 2013-12-16 12:19:14 -0500 )edit

So your RDO deployment is on bare metal and not on top of ESXi or vSphere?

antonnoble gravatar imageantonnoble ( 2013-12-16 13:44:43 -0500 )edit

answered 2013-12-17 05:25:29 -0500

Anand TS gravatar image

updated 2013-12-17 05:26:21 -0500

Hi ,

If you want to assign floating ip's to vm manually you can set like this in your

/etc/nova/nova.conf file



I believe your vm failed to launch because the above option is enabled in nova configuration file and all of the floating IP addresses have already been allocated or (you didn't have a free floating ip in the available ip pool).In that case the nova boot command will fail with an error.

Instead of automatic assigning floating ip, you can try attaching floating ip to instance from dashboard itself.

For adding floating ip, for eg ; if your host ip is and you want to assign to your VM.

#nova floating-ip-bulk-create

Attach this ip to your VM through dashboard or command line.

I just wanted to know how you moved servers from vmware to openstack? I believe that you moved the vmdk file of particular instance from esx servers and uploaded in to glance and trying to create an instance.

Regards, Anand TS

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I have not moved anything form vmware to openstack. I am just trying to get openstack to work on a flat network no dhcp first.

trumpjk gravatar imagetrumpjk ( 2013-12-20 15:14:40 -0500 )edit

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Asked: 2013-12-04 10:28:42 -0500

Seen: 2,321 times

Last updated: Dec 17 '13