From mboxrd@z Thu Jan  1 00:00:00 1970
From: Charles Duffy <Charles_Duffy@messageone.com>
Subject: Re: KVM bridge Networking and openvpn
Date: Mon, 08 Sep 2008 21:32:55 -0500
Message-ID: <ga4n97$tf1$1@ger.gmane.org>
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jd wrote:
> Now when I create new VM, using the command line...
> 
> qemu-system-x86_64 -net nic,vlan=0,macaddr=00:16:3e:70:8f:33 -net tap,vlan=0 -hda /mnt/vm_data/test_xp.hda.disk.xm -m 256
> 
> The VM does not seem to get the IP address :( (may be dhcp request is failing)

You aren't providing ifname or script arguments to your qemu -net tap; 
are you quite sure that tap1 is the device the qemu instance is 
creating? It would probably be safer to use "-net 
tap,vlan=0,script=/path/to/script", where the script in question looks 
like the following:

#!/bin/sh
/sbin/ifconfig "$1" 0.0.0.0 up
/usr/sbin/brctl addif br0 "$1"

BTW, you *do* have a DHCP server connected to the bridge somewhere that 
should be answering these requests, right? :)

Another thing -- use tcpdump or a similar tool to sniff the bridge on 
the host and see if you see DHCP requests from the client while it's 
coming up; if so, you know that you're bridged correctly; if not, you've 
got a place to start.