[ovirt-users] [ovirt 3.6] Logical network not working

[Luca 'remix_tj' Lorenzetto]

On Wed, Sep 14, 2016 at 10:54 AM, Edward Haas <ehaas at redhat.com> wrote:
> If I understood correctly, the VM cannot ping the gw/pc even without vlans in
> place.
> Do you have multiple macs on the VM itself? (like a bridge or some sub
> interfaces)

No, i have not.


> The only thing that comes to my mind is the mac-spoofing that is enabled by
> default,
> it restricts the VM from using more than one mac address to communicate
> through a
> vnic.

No, now is a simple VM with one NIC.

> Except that, I do not have a good idea on what may be wrong.
> Your best friend is tcpdump, make sure you do not see any vlan/tagged
> packets on
> the bridge. (if a tagged packet enters from eno5, it will pass to the bridge
> as is, even
> passed to the vtap as is... the VM will drop it as it does not expect a tag
> there)
>

This is what i get with

tcpdump -e -n -i Development arp

11:04:12.285320 00:1a:4a:16:01:51 > Broadcast, ethertype ARP (0x0806),
length 42: Request who-has 10.5.31.254 tell 10.5.28.211, length 28
11:04:12.285348 00:1a:4a:16:01:51 > Broadcast, ethertype ARP (0x0806),
length 42: Request who-has 10.5.31.254 tell 10.5.28.211, length 28
11:04:12.289081 00:00:0c:07:ac:01 > 00:1a:4a:16:01:51, ethertype ARP
(0x0806), length 60: Reply 10.5.31.254 is-at 00:00:0c:07:ac:01, length
46


instead, with tcpdump -e -n -i vnic0 arp

11:14:13.344807 00:1a:4a:16:01:51 > Broadcast, ethertype ARP (0x0806),
length 42: Request who-has 10.5.31.254 tell 10.5.28.211, length 28
11:14:13.344834 00:1a:4a:16:01:51 > Broadcast, ethertype ARP (0x0806),
length 42: Request who-has 10.5.31.254 tell 10.5.28.211, length 28

On eno5, i get instead this:

11:15:57.355926 00:1a:4a:16:01:51 > Broadcast, ethertype ARP (0x0806),
length 42: Request who-has 10.5.31.254 tell 10.5.28.211, length 28
11:15:57.355944 00:1a:4a:16:01:51 > Broadcast, ethertype ARP (0x0806),
length 42: Request who-has 10.5.31.254 tell 10.5.28.211, length 28
11:15:57.358683 00:00:0c:07:ac:01 > 00:1a:4a:16:01:51, ethertype ARP
(0x0806), length 60: Reply 10.5.31.254 is-at 00:00:0c:07:ac:01, length
46

I can't copy/paste from the vm, but same tcpdump on the vm will show
only arp requests outgoing and no arp reply incoming.

For better clarification:

00:1a:4a:16:01:51 is the mac address of eth0 of the VM
00:00:0c:07:ac:01 is the mac address of the router interface (10.5.31.254)
fe:1a:4a:16:01:51 is the mac address of vtap nic0

As you can see arp reply arrives to eno5 and to the bridge
Development, but arrives not to the vtap vnic0.

This is the issue, because if i set with a static arp entry on the VM
(arp -s 10.5.31.254 00:00:0c:07:ac:01) ping succeeds.

Luca


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Luca 'remix_tj' Lorenzetto, http://www.remixtj.net , <lorenzetto.luca at gmail.com>