Re: [Xen-users] xen 3.2 change in bridge behavior is causing problems

["Todd Deshane" <deshantm@xxxxxxxxx>]

On Tue, Jul 1, 2008 at 5:17 AM, Tomoki Taniguchi <tomoki.taniguchi@xxxxxxxxx> wrote:

i have recently upgraded one of my xen servers from running ubunty
7.10 (gutsy) to ubuntu 8.04 (hardy)
to test xen 3.2 prior to upgrading the rest of the xen 3.1 servers.

my servers have 2 interfaces
eth0 is attached to the lan
eth1 is attached to the wan

on xen 3.1 to create the bridges for domUs i would run the following script

#!/bin/sh
dir=$(dirname "$0")
"$dir/network-bridge" "$@" vifnum=0 bridge=xenbr0 netdev=eth0
"$dir/network-bridge" "$@" vifnum=1 bridge=xenbr1 netdev=eth1

which created a seperate bridge interfaces
xenbr0 and xenbr1 apart from the eth0 and eth1

the domU was able to access the eth1 interface via xenbr1
even if  the dom0s eth1 was not up.

but since switching to 3.2 i have heard the behavior has cahnged and
xenbr are no longer created
and that the interface name equals the bridge name.  so i have
modified my script to the following

#!/bin/sh
dir=$(dirname "$0")
"$dir/network-bridge" "$@" vifnum=0 bridge=eth0 netdev=eth0
"$dir/network-bridge" "$@" vifnum=1 bridge=eth1 netdev=eth1

domUs have no problem accessing the LAN (eth0),
but i have been having lots of problems with the domUs accessing the WAN (eth1)

what i have come to realize is that since i don't set eth1 to up on
the dom0 (don't want to be able to access the xen server itself from
the WAN)
eth1 remains in the down state.

this wasn't a problem when the bridge interface was seperate,
but now that eth1 is the bridge interface as well as the eth1
interface for dom0,
i have to specifically call "ifconfig eth1 up" on boot to allow my
domUs to access eth1

is there some way to avoid this?

is there some way to have xenbr0 and xenbr1 seperate from eth0 and eth1?

There is actually nothing that forces you to use eth0 and eth1 as the bridges.

You can make a bridges in the /etc/network/interfaces file manually and attach
bridge ports for eth0 and eth1 respectively

here is an example that would go in /etc/network/interfaces

auto br0
iface br0 inet static
  address 192.168.133.7
  netmask 255.255.255.0
  broadcast 192.168.133.0
  bridge_ports eth0
  bridge_fd 9
  bridge_hello 2
  bridge_maxage 12
  bridge_stp off

Cheers,
Todd

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