[Users] why ovirt does not support NAT network

[Mark Wu]

On 03/08/2013 05:16 AM, Dan Kenigsberg wrote:
> On Thu, Mar 07, 2013 at 03:57:49PM +0100, Adrian Gibanel wrote:
>> Just in case it might help you please check:
>>
>> http://lists.ovirt.org/pipermail/users/2012-April/001751.html
> This is almost 1 year old, but I did not notice it yet. I love the
> detailed solution!
+1 on NAT network.  Except that it can save ip address, it also could 
reduce the external physical switch's pressure on mac table. Because the 
VM's
mac address is invisible to external switch.

But there're two limitations of NAT network compared with physically 
bridged network:
1. The VMs attached to the same NAT network, but on different hosts 
can't hear each other.  It could be resolved by constructing a tunnel or 
tunnels
     among the hosts in the same cluster and centralizing the mac 
address management of dnsmasq on ovirt engine.

2. The VMs in NAT network are hidden behind the host. The external host 
can't initiate a connection to the VM.  I think it's fine for a desktop VM.\
For a server VM, it can't be resolved by add a DNAT rule on demand. It's 
similar to the 'floating ip address' in quantum.

////
>
> Yes, the rant there, about ovirt network being tightly-coupled with a
> physical interface, is 100% justified. I'm trying to address some of
> that in http://www.ovirt.org/Features/Nicless_Network but it's a long
> way to go.
>
>> I managed to implement Virtualbox-hostonly-alike networks gathering more info from:
>> http://libvirt.org/formatnetwork.html
>> .
>> You might be also interested in: http://wiki.libvirt.org/page/Networking although I didn't use it myself.
>>
>> You might probably already know this information but, just in case, here it is.
>>
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>

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