[Fedora-xen] Fedora Core 8 + Xenbr0 + network bridging?
David Levinger
davidl at matissenetworks.com
Fri Jan 4 01:29:22 UTC 2008
Hey all,
I've been meaning to respond to this for quite awhile but work is crazy,
then the holidays etc etc. We were finally able to get this working on
Centos 5.1, though I'd hazard the same would work for Fedora 8 as I have
that running on my desktop and was able to reproduce what I found on
that system.
We now have this going on several bonded NIC machines with a whole bunch
of Xen Virtual machines going and man oh man it's great!
The heart of the issue seemed to be that we were working with a Bonded
nic and for some reason as soon as we bonded them virt-manager no longer
recognized anything.
What I was able to figure out was that as soon as you remove the
"HWADDR=00:00:00:00:00:00" line from your ifcfg-eth0 file virt-manager
no longer recognizes it as a valid bridge device. HOWEVER, if you use
virt-install from the command line you can STILL point it to the bridge
and it will work for the install and function from that point on NP. But
you cannot install through virt-manager.
I'm pretty sure that this is a bug, but it's possible that I'm missing
something so I wanted to pass it onto all you folks that were so helpful
when I was struggling through this the first time.
On my Fedora 8 desktop if I remove that HWADDR line from ifcfg-eth0 then
I can no longer select my bridge, but as soon as I add it back I can
once again select it.
The process that I went through to get this successfully function went
as follows (It was awhile ago, so if anyone tries this and runs into
anything not listed please let me know):
1. Install OS with both nics connected to non-bonded pair of connections
in the switch, both setup to be DHCP to make sure that both pull an
address.
2. After install I virsh net-undefine default and in
/etc/xen/xend-config.sxp comment out the line (network-script
network-bridge) and add the line (network-script /bin/true)
3. In /etc/xen/scripts/network-bridge I comment out the line
netdev=${netdev:-eth${vifnum}} and add the line netdev="bond0"
4. I create the bond normally, reboot and move the network connection to
the bonded pair on the switch and test to make sure the bond is fully
functional.
5. Once the bond is proved working I go back to
/etc/xen/xend-config.sxp, and uncomment (network-script network-bridge)
while commenting out (network-script /bin/true) Then I reboot so that it
can get the Xen bridge configured to use the bond.
6. After reboot you should see bond0, eth0, eth1, pbond0 and xenbr0
letting you know that the bridge is configured and ready to go. If you
try and create through virt-manager you will have NO option for bridged
networking, BUT if you run: virt-install --bridge=xenbr0 you can use the
bridge to setup machine NP!
Thanks for all of your help, there is no way I'd have been able to
figure out everything I did without insights from each of you. I'm
exceptionally satisfied with the end product and Long Live Xen!
David
-----Original Message-----
From: fedora-xen-bounces at redhat.com
[mailto:fedora-xen-bounces at redhat.com] On Behalf Of Mark Nielsen
Sent: Wednesday, December 05, 2007 11:59 AM
To: Christian Lahti
Cc: fedora-xen at redhat.com
Subject: Re: [Fedora-xen] Fedora Core 8 + Xenbr0 + network bridging?
Christian,
Sorry to hear it didn't work out for you. It's not a straight-forward or
simple configuration. The problem is that there are so many possible
combinations of VLANs, bonds, networks that most of the configuration is
left up to the ability and knowledge of the administrator. It sounds
like you might've missed a few steps somewhere along the way. I admit
that my document isn't 100% step-by-step, it takes a pretty good
understanding of everything that's going on. Your problem could be in
your step where you "Restart networking". This stuff all needs to happen
in a particular order, and that might not have happened. Unfortunately
it's nearly impossible to help troubleshoot that in e-mails. I can say
that I have the configuration I describe (and it sounds like what you
want) working perfectly, so I know it's possible.
Mark
Christian Lahti wrote:
> Hi Mark:
>
>
>
> Well,
>
>
>
> I carefully went through your PDF document for setting up a bonded
pair
> on RHEL 5.1 and at the end of the day this does not work for me. This
> is the procedure more or less I have tried:
>
>
>
> * Make sure eth0 and eth1 work as normal eth devices without LACP
> * Edit /etc/modprobe.conf to add the bonding kernel module
> * Edit /etc/sysconfig/network-scripts/ifcfg-eth0 and ifcfg-eth1 to
> be slave devices with the master as bond0
> * Create /etc/sysconfig/network-scripts/ifcfg-bond0 with static IP
> info
> * Plug into LACP enabled ports on switch and reboot the box
> * At this point bond0 works fine, as expected, we have been doing
> this all day long on non-xen kernels for years
> * NOW...following your document
> * Remove the /etc/libvirt/qemu/networks/autostart/* so that the
> pointless 192.168.122.x NAT network does not get created
> * Grab the network-scripts-bridge-bond-vlan script from the link
> in the message and put into /etc/xen/scripts
> * Edit /etc/xen/xend-config.sxp and replace (network-script
> network-bridge) with (network-script network-bridge-bond-vlan)
> * Restart networking
> * At this point networking for the physical host in invariably
> completely hosed, and there is no xen networking at all
> * It is noteworthy to add that I did not make any modifications to
> the network-scripts-bridge-bond-vlan script as you suggest since I am
on
> a single vlan (so far) and the default setup in the script seems sane
> for a single NON-VLAN bond0 configuration
>
>
>
> So in a nutshell the it seems that libvirt interface just does not
seem
> to use the xen scripts...rather it's own (undocumented?) crap. After
a
> week of head-banging on this we really have no choice but to abandon
> Redhat in favor of Suse 10.3, which incidentally works right out of
the
> box with bridge, NAT, bond, you name it. I suggest RH staff install a
> copy of this to see how they did it, you don't even have to jump
through
> hoops to configure a bond from the command line, you can do this with
> their stock GUI tools if you so choose. I am not knocking RedHat, but
> we need something that "just works" and so far for xen + bond + RH has
> been a non-starter for us after much effort. By the way, to get
> networking un-foobar'ed on the physical machine I have to run
> system-config-network and remove all Ethernet devices, then reboot,
then
> redefine eth0 and eth1 as as normal DHCP devices. I can then go
> re-setup the bond0 device from the command line.
>
>
>
> If anyone has step-by-step directions on how to do this with RHEL 5.1
I
> am happy to try again at some future point. The goals are simple:
>
>
>
> * Step one: create a bond0 from eth0 and eth1 that can be used as
> a bridged device by xen on a single VLAN
> * Step two: create a bond0 (aliases?) that can be assigned
> multiple VLANs, AND have these VLAN devices available to be used by
xen
>
>
>
> I would settle for item #1 really.
>
>
>
> /Christian
>
>
>
>
>
>
>
>
>
>
>
> ________________________________
>
> From: Christian Lahti
> Sent: Saturday, December 01, 2007 3:56 PM
> To: mnielsen at redhat.com; fedora-xen at redhat.com
> Subject: RE: [Fedora-xen] Fedora Core 8 + Xenbr0 + network bridging?
>
>
>
> Hi Mark:
>
>
>
> Thank you very much for your response, I did indeed read the original
> poster as Dale by mistake :) So what you are saying makes perfect
sense
> to me and sounds like exactly what we are after, I will have 3 vlans
to
> bridge myself ultimately. My next question is the relative merits of
> RHEL5.1 as compared to Fedora 8. Obviously I would prefer the stable
> enterprise release rather than bleeding edge Fedora, but has fully
> virtualized windows performance been fixed in this release? At any
rate
> I am looking forward to getting this up and running tomorrow!
>
>
>
> /Christian
>
>
>
>
>
> ________________________________
>
> From: Mark Nielsen [mailto:mnielsen at redhat.com]
> Sent: Sat 12/1/2007 3:19 PM
> To: Christian Lahti
> Subject: Re: [Fedora-xen] Fedora Core 8 + Xenbr0 + network bridging?
>
> hmm, did you mean "Hi Mark" ??
>
> I have 8 Dell 2950s running RHEL 5.1 (new libvirt with that funky NAT
> they added). I have 4 NICs in each; 2 copper, 2 fiber. I bond the 2
> copper (eth0 and eth1) and call it bond0. bond0 carries my "private"
IP
> for cluster suite communications on the dom0 (physical) cluster.
>
> Then I bond eth2 and eth3 (fiber) in to bond1. I lay down the public
> network for the dom0 cluster on bond1.100 (for example, that would be
> VLAN 100). I also add many (up to 10 or so now) VLANs on bond1
> (bond1.20, bond1.21, bond1.22, etc). Then I create xen bridges to each
> of these bond/VLAN devices. This allows me to put any particular VM on
> any particular (or combination up to 3) of these xen bridged bonded
VLAN
> device.
>
> My document explains, in detail, how to do all of this :) The only
added
> step is that I have to "undefine" (virsh net-undefine default) the
> default network that the new libvirt creates (virbr0). Even with this
> new NAT thing they added, I've been told (by our devs) that the
> preferred way to do static network configurations is with the method I
> lay out. NAT is more for dynamic networks (cable modems, dial-up,
wifi,
> etc).
>
> I'm pretty sure there weren't any significant changes in Fedora 8
(we've
> dropped the word "core" now, btw) that don't exist in RHEL 5.1 with
> respects to the network. 5.0 -> 5.1 is when that NAT change came down
> the pipe.
>
> Mark
>
> p.s. I'm happy to answer any other questions you may have about my
> document. I'm quite certain that, if you follow it, you'll have what
> you're looking for.
>
> Christian Lahti wrote:
>
>> Hi Dale:
>>
>> I work with David who posted the original question to the mailing
>> list. I think we need to give a bit more background info on what we
>> are trying to do. We are running a mixed environment of mostly
CentOS
>> 3, 4and 5, we do have a few windows servers and XP systems as well.
>> We are looking to virtualize all these platforms. Normally we have a
>> bonded pair of NICs for the physical hosts, we were able to get this
>> running using CentOS 5 x86_64 with no problems, the guest machines
use
>> the bonded pair in bridged mode as expected after a bit of tweaking.
>> The biggest issue we found with EL5 is that windows guest performace
>> is dismal at best, hence our decision to have a look at Fedora Core 8
>> x86_64. I am happy to report that performance for all of our guest
>> platforms is *very* good with FC8, but it seems that libvirt changed
>> the way networking is setup for Xen. The default NAT configuration
is
>> pretty useless for production server environment. Thanks to the
>> mailing list we are now able to bridge a single NIC on FC8 (like eth0
>> for example), but we cannot figure out how to get a bridge for bond0
>> (comprised of eth0 and eth1) defined and available to Xen. All the
>> tweaks that worked find on EL5 have not worked so far on FC8. I am
>> going to review your document tomorrow and give it a try, but any
idea
>> on whether your methodology will work on FC8 and libvirt? I am
>> willing to blow a Sunday to get this worked out once and for all :)
>>
>> Basically we are after good performance on both para and fully
>> virtualized guests using a bonded pair of GB NICs for speed and
>> redundancy. If this can be achieved with enterprise linux then that
>> would be preferable, but we will go FC8 if the bonding thing can be
>> sorted out. By the way Xensource 4.x looks to be a respin of RHEL5
>> and has pretty good performance but their free version is limited to
>> 32bit (and hence 4GB ram). Adding the clustering failover is the
next
>> step of course :)
>>
>> Thanks again for the help so far.
>>
>> /Christian
>>
>>
>>
>>
>> just FYI for the list, I have a how-to for a bonded and VLAN tagged
>>
> network.
>
>> http://www.certifried.com
>>
>> ODT and PDF formats available.
>>
>>
>> It might not be the best way, but I've sent it out to my colleagues
>> several times and have never received any negative feedback.
>> Mark
>>
>>
>>
>> Dale Bewley wrote:
>>
>>
>> I haven't done bonding, but you should be able to bond them and
>>
> then compose a bridge on top of this bonded device I would think.
>
>> --
>> Dale Bewley - Unix Administrator - Shields Library - UC Davis
>> GPG: 0xB098A0F3 0D5A 9AEB 43F4 F84C 7EFD 1753 064D 2583 B098
A0F3
>>
>> --
>> Fedora-xen mailing list
>> Fedora-xen redhat com
>> https://www.redhat.com/mailman/listinfo/fedora-xen
>>
>>
>>
>>
>
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