Re: [Xen-users] Xen 4.1.0, multiple network interfaces, network-bridge failing to create multiple bridges

[Joseph Glanville <joseph.glanville@xxxxxxxxxxxxxx>]

Hi,

The Xen networking article is very out of date, one of the reasons I
wish to write a new one to better reflect the state of virtual
networking with Xen

In terms of pairs of network adapters, yes this still holds true.
Within the Xen dom0 a virtual "vif" (virtual interface) is created for
each network device within each domU.
As such the devices are paired in a fashion similar to this:

dom0 vif1.0 -> dom1 eth0
dom0 vif4.3 -> dom4 eth3

Working with VLANs is somewhat less trivial. You do however have a
number of options.
First is creating each of the VLAN attached sub interfaces in dom0 and
creating a bridge for each, followed by attaching VMs using the
bridging scripts.
ie.
vconfig add eth0 5
brctl add xenbr0
brctl addif xenbr0 eth0.5

The second however I highly recommend which is utilising Open vSwitch,
which can tag packets with VLANs along with a number of other very
powerful things. Powered by the OpenFlow syntax it puts you in
complete control of your virtual networking infrastructure.



On 6 May 2011 19:08, Jan Vejvalka <jan.vejvalka@xxxxxxxxxxxxxxx> wrote:
> On 5.5.2011 19:19, Joseph Glanville wrote:
>>
>> Hi,
>>
>>> From your original post I can gather you wish to create 2 bridges, one
>>
>> each for the interfaces eth0 and eth1?
>>
>> This can be achieved by running the following:
>> brctl addbr xenbr0
>> brctl addif xenbr0 eth0
>> brctl addbr xenbr1
>> brctl addif xenbr1 eth1
>>
>> Slackware doesn't have a nice way of doing this with it's internal
>> networking system but adding the above to rc.local accomplishes the
>> job good enough.
>
> Thanks - that's simple enough (and that's what I like on Slack, that it
> does not create complicated ways to hide simple things).
>
>> To make use of a multiple bridge setup effectively you need to specify
>> the bridge in the vif statement of the xen config file (something like
>> bridge=xenbr0)
>>
>> Note, only network-bridge and associated are depreciated.
>> You still require the vif-bridge script to be enabled in
>> /etc/xen/xend-config.xcp
>>
>> When domains are created Xen will create the vif adapters to the
>> following naming convention:
>> vif<domid>.<adapternumber>
>>
>> So for a domid of 5 and a system with 2 adapters the following vif
>> devices will be created in dom0:
>> vif5.0
>> vif5.1
>>
>> During device hotplug the vif-script then brings this interface up and
>> adds it to the bridge.
>>
>> Do you have any further questions or need any further clarification on
>> any of the points above?
>
> - There are "7 pairs of connected virtual ethernet interfaces for Dom0"
>  mentioned in http://wiki.xensource.com/xenwiki/XenNetworking . Is
>  that still valid ?
>
> - Not sure how VLANs are handled by the bridges; two setups come to my
>  mind: either connecting the specific VLAN (e.g. eth0.5) to xenbrX in
>  Dom0 or connecting all eth0 and selecting the right VLAN(s) on the
>  ethernet interface in DomU. Both ways can have their pros and cons,
>  are both possible ?
>
> Otherwise it's clear enough at the moment, thanks :-)
>
>> I am considering writing an article on Xen Wiki about how network
>> configuration is carried out in Xen as it seems to be an area alot of
>> people have problems with.
>
> That would definitely be most useful.
>
> Thanks,
>
> Jan
>
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>



-- 
Kind regards,
Joseph.
Founder | Director
Orion Virtualisation Solutions | www.orionvm.com.au | Phone: 1300 56
99 52 | Mobile: 0428 754 846

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