[one-users] OpenNebula + DHCP

Manish Sapariya manish at gslab.com
Mon Nov 29 23:24:55 PST 2010

This is exactly what I do. The downside for
me is that I do not control the DHCP server
and it brings its own problems, mostly operational.

Thanks and Regards,

On 11/30/2010 5:36 AM, Carsten.Friedrich at csiro.au wrote:
> There is (at least) one more, which I think is the most general and easy to run once set up, if:
> * You want the VMs to be part of your general network.
> * You have a DHCP server in your general network.
> * You have a fixed set of addresses you want to VMs to use and which are not used by any other machines on the network.
> Then:
> * Create a bridge on all cloud nodes with the same name (e.g. br0) and bind the NICs on each server to it.
> * Create a OpenNebula virtual network with fixed, free addresses like:
> NAME = "Small network"
> BRIDGE = br0
> LEASES = [ IP="x.y.z.65"]
> LEASES = [ IP="x.y.z.66"]
> LEASES = [ IP="x.y.z.67"]
> LEASES = [ IP="x.y.z.72"]
> LEASES = [ IP="x.y.z.73"]
> ...
> ...
> * Add entries to your DHCP server binding the MAC address OpenNebula will generate for the VM to the corresponding fixed IP. (the MAC address will be a configurable prefix + the IP address in hex).
> * Configure your VM images to use DHCP.
> Now, when you start a VM, it will get a MAC address from OpenNebula (no context necessary) and then an IP address from your DHCP server.
> Carsten
> -----Original Message-----
> From: users-bounces at lists.opennebula.org [mailto:users-bounces at lists.opennebula.org] On Behalf Of Ruben S. Montero
> Sent: Monday, 29 November 2010 6:32
> To: SZÉKELYI Szabolcs
> Cc: users at lists.opennebula.org
> Subject: Re: [one-users] Opennebula + DHCP
> Hi
> There are three options to set up networking for a VM:
> 1.- Use static IPs, i.e hard-coded in the VM image. This is useful for
> "well-known" services, but usually people do not use this approach as
> it prevents an "install once deploy many" strategy
> 2.- Use specialized networking VMs,  that runs a DHCP server and
> probably any other network related services (DNS, VPN server, routers,
> proxy of any kind). This is useful for VM packs, where you define
> vnets. Vnets in OpenNebula can be implemented with ebtables (works
> out-of-the-box, see [1]) and with VLAN at the switch level (either
> setting the vnets before hand, or with a hook to configure the swtich,
> e.g. openvswitch)
> 3.- Context. Context is not just for passing network config parameters
> but also for basic service configuration attributes (e.g. ssh keys).
> This is  the best approach for stand-alone VMs and probably also for
> the virtual network example. It only requires to prepare network configuration
> script of the OS to get the IP from the context device.
> However, the best approach should be more or less clear depending on
> the use-case you are trying to deploy, the networking of your cloud...
> Cheers
> Ruben
> [1] http://www.opennebula.org/documentation:rel2.0:nm
> 2010/11/28 SZÉKELYI Szabolcs<szekelyi at niif.hu>:
>> On 2010. November 27. 18:01:24 Steven Timm wrote:
>>> I have never used opennebula with a dhcp server but I think you would
>>> have either have to use the contextualization scripts to pass in
>>> a modified ifcfg-eth0 that calls for DHCP address, or save a special
>>> original image that has them already.  Also you would have to configure
>>> the onevnet so you knew which range of MAC addresses your machines were
>>> going to have.
>> Being badly dissatisfied with "contextualization" (there's no ifcfg-eth0 on
>> Debian-based systems for example, not mentioning non-GNU/Linux OSes), we
>> solved this problem by implementing DHCP on our virtual networks. On VM
>> creation, a hook script registers the MAC address and the IP address in the
>> DHCP server that assigns it to the VM upon DHCP request. This requires the
>> machine running the DHCP server (or a DHCP relay) to have an interface in the
>> network used for VMs, but this is usually not a problem as long as you use
>> 802.1q tagged virtual networks. This can be implemented for ebtables-based
>> vnets as well, but requires a bit tricker setup.
>> I can provide you with more deatils or even code if interested, but currently
>> I don't have time to make proper redistributable and configurable packages.
>> Cheers,
>> --
>> cc
>>> On Sat, 27 Nov 2010, Tim Bordemann wrote:
>>>> Hi,
>>>> I'm currently evaluating Opennebula for a university's project.
>>>> So far I installed Opennebula and am able to start virtual machines on
>>>> the server nodes.
>>>> Unfortunately I am not sure, how to configure Opennebula or the virtual
>>>> machine template so that the vm gets it's IP address from the
>>>> DHCP-server. Could anyone please send me a sample vm template?
>>>> Thanks in advance.
>>>> Tim
>>>> _______________________________________________
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>>>> Users at lists.opennebula.org
>>>> http://lists.opennebula.org/listinfo.cgi/users-opennebula.org
>> _______________________________________________
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