Re: [Xen-users] is it a good idea to share an IP with dom0 & domU?

[Rudi Ahlers <Rudi@xxxxxxxxxxx>]

Nick Couchman wrote:
> You can't "share" an IP with your server.  If your dom0 has an IP 
> assigned by the ISP for you to access it to manage, you cannot assign 
> that IP to any other domU on the system.  IPs must always be unique.  
> With bridging, each domU must have an IP that the network connected to 
> the bridge can see.  So, if your dom0 eth0 has an IP address and you 
> set up a bridge for the domUs to access and want them to communicate 
> with the dom0 and on the same network as the dom0, they need to be on 
> the same subnet and have the same subnet mask.  The other option is to 
> do some sort of NAT setup using the dom0 IP address and iptables (e.g. 
> on a Linux-based dom0) so that your domUs use NAT to see the outside 
> world.  In this setup you can use port forwarding on the dom0 to 
> forward certain services into the domUs, but each port can only 
> forward to a single domU.
>  
> -Nick
> >>> On 2008/06/20 at 16:41, Rudi Ahlers <Rudi@xxxxxxxxxxx> wrote:
> Hi all
>
> I wonder if someone can give me some suggestions, from experience on this.
>
> We have 4 IP's per server, and I'd like to use them wisely. dom0 won't
> really be used, other than accessing / managing / monitoring domU's.
>
> So, is it wise to share the main IP of the server with a domU ?
>
> And from what I understand, this is bridging, right? I need to access
> the domU directly from the internet, via the IP that our ISP has
> assigned to us.
>
> --
>
> Kind Regards
> Rudi Ahlers
> CEO, SoftDux
>
> Web:   http://www.SoftDux.com
> Check out my technical blog, http://blog.softdux.com for Linux or 
> other technical stuff, or visit http://www.WebHostingTalk.co.za for 
> Web Hosting stuff
ok., so you're saying I should have 1.2.3.4 for dom0, and then 1.2.3.5 
for domU, right?
I'm trying to understand this whole setup still, so bear with me please :)

Here's my current setup:

1x server with 2x NIC's (192.168.10.30 & xxx.xxxx.xxx.145). We're going 
to use the 192.168.10.30 IP / subnet to communicate between servers on a 
VLAN in the DC. The other server runs on 192.168.10.31, and then I have 
setup a Linux domU with 192.168.10.32, and a Windows domU as 192.168.10.33
Our ISP has assigned us a total of 4 IP's, which means xxx.xxx.xxx.145 
is assigned to the Linux dom0 & xxx.xxx.xxx.149 to a Windows VMWare 
server (the 192.168.10.31 machine). I now have xxx.xxx.xxx.146 & 147 
left to use on domU's on the Linux server, and I was hoping to have a 
3rd domU, using the main IP to access the domU as well.
But I see that my approach was wrong, so I'll have to rethink this a 
bit, thank you :)
--

Kind Regards
Rudi Ahlers
CEO, SoftDux

Web:   http://www.SoftDux.com
Check out my technical blog, http://blog.softdux.com for Linux or other 
technical stuff, or visit http://www.WebHostingTalk.co.za for Web Hosting stuff


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