[CentOS-virt] Re: CentOS-virt Digest, Vol 7, Issue 22

Sat Mar 29 00:39:42 UTC 2008
Hristo Benev <foxb at abv.bg>

Already reported....


 >Subject: RE: [CentOS-virt] xenbr0 isn't created anymore
 >To: <centos-virt at centos.org>
 >	<E2BB8074E5500C42984D980D4BD78EF9022A704E at 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.
 >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.
 >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.