[one-users] external DHCP

[Ruben S. Montero]

Hi Andreas

No there is no problem to use an external DHCP server. In fact, it is
common to use it as part of the virtualized infrastructure (i.e.
people put a DHCP server in a VM). In order to isolate DHCP requests
from other users/applications VLANs should be used, as in your setup.

When you define a network in OpenNebula there are basically two parts:
(i) a physical configuration (e.g. bridges or VLANIDs if needed) and
(ii) a MAC/IP address space.

About (i). If your infrastructure is already using VLANs and you have
configured the interfaces in the hosts you do not need to use the VLAN
drivers, just define the target bridge for your VMs. You may benefit
from the automatic set up of the OpenNebula network drivers, though.

About (ii). The main purpose is to assign a unique MAC address to each
NIC, the IP assignment has to be done later at boot time, either by a
DHCP server or by the init scripts of the VM (IP's are derived from
MACs).

Hope it helps,

Cheers

Ruben

On Wed, Mar 21, 2012 at 9:15 AM, Andreas Calvo <andreas.calvo at scytl.com> wrote:
> Hello,
> We're building a VM farm with OpenNebula.
> However, I'm a little bit confused about how to handle networking.
> Our scenario is based on VLAN tagging and external DHCP server for every
> VLAN.
> Our goal is to use that external DHCP server to provide IPs for all VMs.
> When creating a Virtual Network, a mandatory parameter is the range or
> fixed address (otherwise it fails complaining it cannot allocate the VM
> Network).
> We've tried Open vSwitch (without luck -- fails to create the vm
> directory) and 802.1Q (needs an explicit range/fixed address to
> instantiate a template).
>
> Is it possible to use a external DHCP server?
> Is there any issue using any VLAN tagging service (802.1Q or Open
> vSwitch)?
>
> Thanks!
> --
> Andreas Calvo Gómez
> Systems Engineer
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-- 
Ruben S. Montero, PhD
Project co-Lead and Chief Architect
OpenNebula - The Open Source Solution for Data Center Virtualization
www.OpenNebula.org | rsmontero at opennebula.org | @OpenNebula