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Date: Mon, 07 Apr 2014 14:14:08 +0200
From: Wido den Hollander <wido@widodh.nl>
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To: dev@cloudstack.apache.org
Subject: Re: How does a system VM get an IP address?
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On 04/07/2014 12:33 AM, Rafael Weingartner wrote:
> Hi folks,
> I was wondering how a system vm gets an IP address. I know they are the
> first things that CS needs in order to start up others VMs, so when they
> start there is no virtual router to assign IP addresses via DHCP.
>

Via a local virtio socket from the hypervisor in KVM mode. The VM boots 
and via that local serial socket it gets the IP-address.

> I also noticed that on the physical hosts with the VM.Start command CS
> sends some extra data that includes the IPs that the VM should get.
> However, I have no idea how it actually gets those parameters and set its
> IP.

The management server sends this information to the KVM agent. User 
Instances get the IP address via DHCP from the VR, System VMs via the 
local serial socket.

Wido

>
> Does anyone here know how it works?
>