[ovirt-users] R: R: R: R: R: R: R: PXE boot of a VM on vdsm don't read DHCP offer

-----Messaggio originale----- Da: users-bounces(a)ovirt.org [mailto:users-bounces@ovirt.org] Per conto di Michael S. Tsirkin Inviato: giovedì 9 luglio 2015 15:15 A: Fabian Deutsch Cc: users(a)ovirt.org Oggetto: Re: [ovirt-users] R: R: R: R: R: R: PXE boot of a VM on vdsm don't read DHCP offer On Thu, Jul 09, 2015 at 08:57:50AM -0400, Fabian Deutsch wrote: > ----- Original Message ----- > > On Wed, Jul 08, 2015 at 09:11:42AM +0300, Michael S. Tsirkin wrote: > > > On Tue, Jul 07, 2015 at 05:13:28PM +0100, Dan Kenigsberg wrote: > > > > On Tue, Jul 07, 2015 at 10:14:54AM +0200, NUNIN Roberto wrote: > > > > > > > > > > > > On Mon, Jul 06, 2015 at 10:33:59AM +0200, NUNIN Roberto wrote: > > > > > > > Hi Dan > > > > > > > > > > > > > > Sorry for question: what do you mean for interface vnetxxxx ? > > > > > > > Currently our path is : > > > > > > > eno1 - eno2 ---- bond0 ----- bond.3500 (VLAN) ------ bridge ----- > > > > > > > vm. > > > > > > > > > > > > > > Which one of these ? > > > > > > > Moreover, reading Fabian statements about bonding limits, today I > > > > > > > can try > > > > > > to switch to a config without bonding. > > > > > > > > > > > > "vm" is a complicated term. > > > > > > > > > > > > `brctl show` would not show you a "vm" connected to a bridge. When > > > > > > you > > > > > > WOULD see is a vnet888 tap device. The "other side" of this device is > > > > > > held by qemu, which implement the VM. > > > > > > > > > > Ok, understood and found it, vnet2 > > > > > > > > > > > > > > > > > I'm asking if the dhcp offer has reached that tap device. > > > > > > > > > > No, the DHCP offer packet do not reach the vnet2 interface, I can see > > > > > only DHCP DISCOVER. > > > > > > > > Ok, so it seems that we have a problem in the host bridging. > > > > > > > > Is it the latest kernel-3.10.0-229.7.2.el7.x86_64 ? > > > > > > > > Michael, a DHCP DISCOVER is sent out of a just-booted guest, and OFFER > > > > returns to the bridge, but is not propagated to the tap device. > > > > Can you suggest how to debug this further? > > > > > > Dump packets including the ethernet headers. > > > Likely something interfered with them so the eth address is wrong. > > > > > > Since bonding does this sometimes, this is the most likely culprit. > > > > We've ruled this out already - Roberto reproduces the issue without a > > bond. > > To me this looks like either a regression in the host side bridging. But otoh it doesn't look > like it's happening always, because otherwise I'd expect more noise around this issue. > > - fabian Hard to say. E.g. forwarding delay would do this for a while. If eth address of the packets is okay, poke at the fbd, maybe there's something wrong there. Maybe stp is detecting a loop - try checking that.

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