problem with setting up Xen networking

[Amedee Van Gasse]

On 01-02-10 09:39, Werner Schram wrote:

> I personally prefer to manage my bridges manually via
> /etc/network/interfaces, every virtualization platform has its own
> bridge management system, which doesn't always work well with your
> distributions network configuration. I find it strange that your
> bridge is added to the eth0 bridge in your case, as you specificly
> added it to xenbr0 (which wasn't created). I remember seeing the
> eth0-peth0 type of bridge before, but I can't remember how that got
> created. My guess is that it is a misconfiguration in your
> xend-config.sxp.
>
> Anyway, your xen managed bridge configuration is in
> /etc/xen/xend-config.sxp. There should a line like:
> (network-script 'network-bridge bridge=mybridge')
>
> My advice would be to disable that line and configure a bridge in
> /etc/network/interfaces, but if you post that line, maybe we can work
> out what is wrong.

Perhaps I misunderstood you, but I disabled everything in /etc/xen/mx1, 
/etc/xen/xend-config.sxp and /etc/networking/interfaces, except for the 
lo and eth0 dhcp. I changed nothing inside the DomU.

Now when I start the DomU, I get the following error:

eth0: ERROR while getting interface flags: No such device
Failed to bring up eth0.

Of course, no networking.


Next step, configure a bridge more or less as described on 
https://help.ubuntu.com/8.10/serverguide/C/network-configuration.html

this is now my /etc/network/interfaces:

auto lo
iface lo inet loopback

allow-hotplug eth0
iface eth0 inet dhcp

auto dummy0
iface dummy0 inet static
         address 192.168.2.1
         broadcast 192.168.2.255
         netmask 255.255.255.0

auto br0
iface br0 inet static
         address 192.168.2.10
         network 192.168.2.0
         netmask 255.255.255.0
         broadcast 192.168.2.255
         gateway 192.168.2.1
         bridge_ports dummy0
         bridge_fd 9
         bridge_hello 2
         bridge_maxage 12
         bridge_stp off


That gives the following ifconfig:
br0       Link encap:Ethernet  HWaddr 12:a8:13:88:24:29
           inet addr:192.168.2.10  Bcast:192.168.2.255  Mask:255.255.255.0
           inet6 addr: fe80::10a8:13ff:fe88:2429/64 Scope:Link
           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
           RX packets:0 errors:0 dropped:0 overruns:0 frame:0
           TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:0
           RX bytes:0 (0.0 B)  TX bytes:468 (468.0 B)

dummy0    Link encap:Ethernet  HWaddr 12:a8:13:88:24:29
           inet6 addr: fe80::10a8:13ff:fe88:2429/64 Scope:Link
           UP BROADCAST RUNNING NOARP  MTU:1500  Metric:1
           RX packets:0 errors:0 dropped:0 overruns:0 frame:0
           TX packets:4 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:0
           RX bytes:0 (0.0 B)  TX bytes:280 (280.0 B)

eth0      Link encap:Ethernet  HWaddr 00:30:48:db:31:00
           inet addr:10.0.0.12  Bcast:10.0.0.255  Mask:255.255.255.0
           inet6 addr: fe80::230:48ff:fedb:3100/64 Scope:Link
           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
           RX packets:994 errors:0 dropped:0 overruns:0 frame:0
           TX packets:481 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:1000
           RX bytes:103683 (101.2 KiB)  TX bytes:74826 (73.0 KiB)
           Interrupt:16 Base address:0x4000

lo        Link encap:Local Loopback
           inet addr:127.0.0.1  Mask:255.0.0.0
           inet6 addr: ::1/128 Scope:Host
           UP LOOPBACK RUNNING  MTU:16436  Metric:1
           RX packets:0 errors:0 dropped:0 overruns:0 frame:0
           TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:0
           RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

And the output of brctl show:
bridge name	bridge id		STP enabled	interfaces
br0		8000.12a813882429	no		dummy0


Still, when I create the DomU, I get:
eth0: ERROR while getting interface flags: No such device
Failed to bring up eth0.

(I didn't forget to restart the xend daemon.)

I also noticed this:
dmesg | grep -i eth
[    0.000000] Kernel command line: root=/dev/hda1 ro 
ip=192.168.2.101:1.2.3.4:192.168.2.1:255.255.255.0:mx1:eth0:off 
console=hvc0 xencons=tty
[    0.821870] netfront: Initialising virtual ethernet driver.

Notice the "eth0:off"? Could this be of some importance? Hmmm...
So then I added vif = ['bridge=br0'] to /etc/xen/mx1, destroyed & 
re-created and guess what... I can ping both ways now! W00t!

Thank you for nudging me in the right direction. All the rest now is 
only a simple matter of setting up iptables on Dom0 for routing. and I'm 
done.

-- 
Amedee