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Re: Need some assistance concerning HVM guests and VLANs



Manuel Bouyer wrote:
On Thu, May 20, 2010 at 01:05:13PM +0100, Hugo Silva wrote:
[...]
I don't understand why I'm able to bridge msk0 and create vlan
interfaces on the NetBSD domU (and I'm willing to bet on the
OpenSolaris domU too, altough I haven't tried yet - stumped by this
atm) and get connectivity, but not on the FreeBSD guest. Also, it
isn't clear why I'm able to see the vlan3 packets on msk0, but not
on the vlan3 interface (the arp is-at packets never show up on
vlan3, only the who-was from the domU).

If I understand it properly, you have both vlan and bridge on the same
physical interface. In my experience, this doesn't work well,
as packets coming from the physical interface are not duplicated
(one for vlan, one for bridge) so one or the other is missing the
packet.
Either create all vlan in your dom0 and attach bridges to all vlans
(this is how I manage this here - one domU has more than 30 xennet now,
each attached to different vlans in the dom0), or attach a bridge to your
physical interface but don't create any vlan in dom0 (in this case I
guess your dom0 can't have network connectivity).

Note that the vlan in dom0 don't have to be configured with an IP address,
they just need to be up.

Yes, the vlans and bridges are on the same interface. (initially I only had bridge0, but after being unable to configure the FreeBSD domU with VLANs I created bridge1 and vlan3 on the dom0, and now I'm also bridging vlan3 (on bridge1))

Both the NetBSD and OpenSolaris domUs work fine on bridge0 (the one bridging msk0) - NetBSD on vlan 3 and OpenSolaris on vlans 2 and 4. The dom0 itself is on vlan 100.

I have no connectivity problems from/to any of these domUs - and both have VLANs defined in the guest OS:

netbsd$ ifconfig vlan3
vlan3: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1496
       vlan: 3 parent: xennet0
       address: --:--:--:--:--:--
       inet 10.100.3.4 netmask 0xffffff00 broadcast 10.100.3.255

opensolaris$ dladm show-vlan
LINK            VID      OVER         FLAGS
vlan2           2        xnf0         f----
vlan4           4        xnf0         f----




I just tried configuring an OpenBSD HVM domU the same way as above - it doesn't work. I can see ARP packets going out on tap1, but nothing on xvif28.0. Nothing on msk0 at all -- these packets aren't going out of the system at all.

OpenBSD+VLANs work fine -- I have an OpenBSD VLAN router here for testing. As it stands now, there are four guests, two have connectivity and two don't; The two that don't are HVM.

It is likely I haven't properly understood something. But networking wise, why would a PV domU work with VLANs but not a HVM guest?

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