Re: Dom1 always does DHCP requests and vmid increasing

[Mike Wray <mike.wray@hpl.hp.com>]

Mike Brady wrote:

> I don't have tcpdump installed at the moment, but will do so shortly.
> 
> In the mean time I have been playing around a bit and have found the 
> following.
> 
> 1) Putting an ip=192.168.42.36 on the config file stops the DHCP request, but 
> the domain still has two addresses - the 192.168.42.36 and 192.168.42.35 
> (this is what is on the ifcfg-eth0 file).
> 
> 2)  In looking at the create.py script (after a crash course in Python :-) I 
> noticed that the 1.2.3.4 address is actually assigned as the nfsserver 
> address, not the IP address.  To test this I set the nfs_server variable to 
> '169.254.1.0' and now this address shows up in the DHCP server log.  The log 
> entry is below.
> 
> Jul 28 20:49:22 spitfire dhcpd: DHCPREQUEST for 255.255.255.255 (169.254.1.0) 
> from aa:00:00:00:00:11 via eth0: wrong network.
> Jul 28 20:49:22 spitfire dhcpd: DHCPNAK on 255.255.255.255 to 
> aa:00:00:00:00:11 via eth0
> Jul 28 20:49:24 spitfire dhcpd: DHCPDISCOVER from aa:00:00:00:00:11 via eth0
> Jul 28 20:49:25 spitfire dhcpd: DHCPOFFER on 192.168.42.96 to 
> aa:00:00:00:00:11 via eth0
> Jul 28 20:49:25 spitfire dhcpd: DHCPREQUEST for 192.168.42.96 (192.168.42.51) 
> from aa:00:00:00:00:11 via eth0
> Jul 28 20:49:25 spitfire dhcpd: DHCPACK on 192.168.42.96 to aa:00:00:00:00:11 
> via eth0
> 
> I am still looking at the xm code to try and understand it.
> 

xm just assembles the components of the ip= parameter to the kernel.
If you use 'xm create -n' it will print out the resulting configuration
and you will be able to see the kernel ip parameter it will use.

The ip= param to the kernel has the format

ip=ipaddr:nfsserver:gateway:hostname:interface:dhcpmode

and xm defaults it to

ip=:1.2.3.4:::eth0:off

which has DHCP off. So it's a double puzzle, why does the kernel
use dhcp when it's set off, and why is it using dhcp for the
nfs server address anyway?

If the DHCP requests are a problem for you I could add a
parameter to xm create to tell it not to set the ip= param
at all.

Mike


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