Already reported....
http://bugs.centos.org/view.php?id=2516
Subject: RE: [CentOS-virt] xenbr0 isn't created anymore To: centos-virt@centos.org Message-ID: E2BB8074E5500C42984D980D4BD78EF9022A704E@MFG-NYC-EXCH2.mfg.prv Content-Type: text/plain; charset="us-ascii"
Kai Schaetzl wrote:
Somehow I managed to disable the creation of xenbr0 on boot-up of the host system. CentOS 5 with standard CentOS Xen. I changed all Xen VMs to use xenbr0 instead of virbr0 and disabled virtlibd. Works fine. But when I later restarted the machine I found that all networking for guests had gone. On inspection there's no xenbr0 created anymore. I can get it up by stopping network (or eth0) and then running /etc/xen/scripts/network-bridge start xend-config.sxp still has (network-script network-bridge), logging shows no problems. It seems that the network-bridge script simply doesn't run, but why? I can't see any init script or so that might run it, so I assume it's xend doing that, but there's no error in any log.
Kai,
Snooping around I found this in /etc/xen/qemu-ifup:
# # Old style bridge setup with netloop, used to have a bridge name # of xenbrX, enslaving pethX and vif0.X, and then configuring # eth0. # # New style bridge setup does not use netloop, so the bridge name # is ethX and the physical device is enslaved pethX # # So if... # # - User asks for xenbrX # - AND xenbrX doesn't exist # - AND there is a ethX device which is a bridge # # ..then we translate xenbrX to ethX # # This lets old config files work without modification
So it turns out Xen networking changed in current releases and they never updated their Wiki.
Now I am not sure how the vif0.X and vethX interfaces fit into the picture here... Maybe these are no longer used?
vifX.Y interfaces are still used though for linking domU interfaces with the physical interface.
-Ross
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Hristo Benev wrote on Sat, 29 Mar 2008 02:39:42 +0200 (EET):
Already reported....
That looks like something different. Maybe related, but not the same problem. Note, I can create VMs with virt-manager. Unfortunately, the reporter gave the perfect explanation "it doesn't work", so I don't know what he's experiencing. I suppose he may have switched off libvirtd and then virt-manager indeed might not be able to find interfaces.
The problem I describe here happens when starting up xend. Under some not yet known circumstances the network-bridge script won't be able to determine the interfaces to juggle with because the output of ip route list is not what it expects.
Kai
Kai Schaetzl wrote:
Hristo Benev wrote on Sat, 29 Mar 2008 02:39:42 +0200 (EET):
Already reported....
That looks like something different. Maybe related, but not the same problem. Note, I can create VMs with virt-manager. Unfortunately, the reporter gave the perfect explanation "it doesn't work", so I don't know what he's experiencing. I suppose he may have switched off libvirtd and then virt-manager indeed might not be able to find interfaces.
The problem I describe here happens when starting up xend. Under some not yet known circumstances the network-bridge script won't be able to determine the interfaces to juggle with because the output of ip route list is not what it expects.
Yes, the network bridge scripts have problems parsing iputils output in some circumstances it seems.
In Kai's case, I believe it was because he had multiple default gateways with different weights, and ip route would show:
default via 192.168.1.1 dev eth0 src 192.168.1.231
When the scripts were expecting:
default via 192.168.1.1 dev eth0
Since I am using the xen.org 3.2 rpms on my system it was very hard to properly troubleshoot, so that might not be the bottom line here.
-Ross
______________________________________________________________________ This e-mail, and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail, you are hereby notified that any dissemination, distribution or copying of this e-mail, and any attachments thereto, is strictly prohibited. If you have received this e-mail in error, please immediately notify the sender and permanently delete the original and any copy or printout thereof.
-
Hristo Benev -
Kai Schaetzl -
Ross S. W. Walker