View Source: XenNetworking - Waikato Linux Users Group

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[Xen] has a set of scripts which manage the networking between the priviledged and unpriviledged domains. It defaults into bridged mode, but can be set up in a routed mode as well, or with any sort of topology you like.

See the pages at <b>FIXME</b> for a run down on the differences and what is possible.

As of [Xen] 3.0.2 (possibly earlier?), [Xen] will manage renaming your physical [Ethernet] interface to <tt>peth0</tt> (from <tt>eth0</tt>), and will bring up a dummy <tt>eth0</tt> interface with the original [IP] address and join this to the <tt>xenbr0</tt> bridge device. This makes it effectively transparent to the [OS] running in the priviledged domain.

!! Xen and [Debian]'s interfaces file

As of [Xen] 3.0.2, the [Xen]-provided network scripts mean you don't need to do anything special. If you find yourself running an earlier version of [Xen], I use a set of interfaces stanzas like these to manage my networking:

<verbatim>
# The physical device xen will take over. Note that I'm not setting an IP address on this device as
# doing so will interfere with the bridging that occurs later
auto eth0
iface eth0 inet manual

# The xen bridge device. Note that in xen 2.x this should be xen-br0, in xen 3.x is should be xenbr0
auto xenbr0
iface xenbr0 inet static
      bridge-ports eth0
      address 192.168.1.253
      netmask 255.255.255.0
      gateway 192.168.1.254
</verbatim>

This will cause debian to bring up <tt>eth0</tt> without an [IP] address, then bring up a bridge device <tt>xenbr0</tt> and add <tt>eth0</tt> to the bridge, and then set up the [IP] address specified.

Note again: the above is ''NOT'' needed it you are running [Xen] 3.0.2 or more recent!

!! [Xen] and [VLAN]s

As of this writing, it seems there is no nice integration with [Xen] and [VLAN]s. To work around this I use a modification of the above ([Debian]-specific) interfaces file to provide multiple bridges to [Xen], on different [VLAN]s:

<verbatim>
# Physical device accepting vlan-tagged frames
auto eth0
iface eth0 inet manual

# Vlan device
auto eth0.1234
iface eth0.1234 inet manual

# Vlan device
auto eth0.2000
iface eth0.2000 inet manual


# first bridge, for vlan 1234
auto xenbr0
iface xenbr0 inet static
      bridge-ports eth0.1234
      address 192.168.1.1
      netmask 255.255.255.0
      gateway 192.168.1.254

# second bridge, for vlan 2000
auto xenbr1
iface xenbr1 inet static
      bridge-ports eth0.2000
      address 192.168.2.1
      netmask 255.255.255.0
</verbatim>

This will bring up two bridges with the specified [IP] addresses. When you create a [Xen] domU, you can specifiy which [VLAN] (or bridge) it belongs to with the <tt>vif</tt> parameters in its config file:

<verbatim>
# one network interface in the first bridge (vlan 1234)
vif = [ 'bridge=xenbr0']
# two network interfaces, one in each (vlan 1234, vlan 2000)
# vif = [ 'bridge=xenbr0', 'bridge=xenbr1']
</verbatim>

Notes:

* You may have to disable the <tt>network-script</tt> parameter in the [Xen] config file in <tt>/etc/xen</tt>, or else it will try to manage <tt>xenbr0</tt> on its own.
* This may change with newer versions of [Xen] – make sure to check out what [Xen] supports before assuming you have to do it this way!

!! [Xen] and bonded interfaces

I assume this works on the same theory as the example for [VLAN] interfaces. (Again, this may change with newer versions of [Xen] – make sure to check out what [Xen] supports before assuming you have to do it this way!)

!! See also

* LinuxVlanNotes

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Part of CategoryXen, CategoryNetworking
One page links to XenNetworking:
Last edited on Tuesday, July 4, 2006 12:34:22 am by AristotlePagaltzis
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