[Users] Networking questions (LONG)

[Lior Vernia]

Hi Allan,

On 10/01/14 02:16, Alan Murrell wrote:
> Hello Lior,
> 
> Thank you for your reply.
> 

Sure, let's try to get that setup of yours working :)

> Quoting "Lior Vernia" <lvernia at redhat.com>:
> 
>> This way the firewall VM will get something like "eth1" for VLAN 1,
>> "eth2" for VLAN 200 and so forth, which might be close enough to what
>> you described on your previous setup (oVirt currently doesn't allow
>> creating VLANs inside VMs). And if I correctly understood your needs it
>> will save you the trouble you described below (well, you would need the
>> one dummy interface).
> 
> That would be doable, except I am not sure if there is a limit to the
> number of vNICs a VM could have and/or if there is an OS-level limit to
> how many?  It is also a bit "messier" IMO, but that is more of a
> personal issue than a technical one, and one I could probably get over :-)
> 

oVirt does not enforce any sort of limit on the number of vNICs. I
personally don't know about KVM or your VMs' OS, but this should be
Googleable.

> When you say that oVirt currently doesn't allow creating VLANs inside
> VMs, are you referring to the use of VLAN interfaces like I describe
> (e.g., "eth1.1", "eth1.2", "eth1.10", etc.)?  If so, is that an oVirt
> limitation, or a KVM one?
> 

Yes, sorry, I realise now that my phrasing was only half-understandable.
I indeed meant that oVirt doesn't support attaching more than one
network to the same vNIC (be it VLAN-tagged or not). I doubt that this
is a KVM limitation (but I'm no expert on KVM), I think it's just
something that we haven't yet found a strong case for in oVirt.

> I have seen examples where one can create a "Trunk" with KVM and Open
> vSwitch, and I thought for some reason oVirt used Open vSwitch, but none
> of the commands I tried from the examples were found.  A check of
> <http://www.ovirt.org/Features/Node/OpenVSwitchSupport> shows that
> indeed there does not appear to be any integration yet, and it is only
> 60% done :-(
> 

I actually know nothing of the link you provided, but I can offer
alternatives.

If you REALLY want to use OVS with oVirt NOW, you could take advantage
of its integration with OpenStack Neutron. That would require you to
install another machine (should be possible on an all-in-one setup too)
as a Neutron server. This might go smoothly or it might cause you some
headaches.
http://www.ovirt.org/Features/Detailed_OSN_Integration

It will probably become possible in the future to use OVS with oVirt
directly (although I can't promise or commit on the time frame) by
leveraging a development process that's going on in VDSM networking
right now. In fact, if you're a developer you could help make it happen
and control the time frame yourself by contributing to an OVS backend.
http://www.ovirt.org/Feature/NetworkReloaded

> With regards to using the dummy interfaces, I realised I probably do not
> need to add them to a bridge, since they would be physical NICs in
> production (this is just for testing).  I initially did create the
> "ovirtvm" bridge before I realised that, but have made them
> "stand-alone" NICs with no IPs attached to them, but they are not
> "green" in oVirt when I try to attach my logical networks to them under
> "Networks > Hosts > vmhost01 > Setup Host Networks".
> 
> When I am in "Setup Host Networks", I see my dummy interfaces, but they
> have a red dot instead of a green one (like what "eth0" has). I can my
> logical networks to them, but the "Network Device Status" has a red
> arrow pointing down.  Here are my ifcfg-dummy* files:
> 

I'm not an expert on these things, but this "Down" status is basically
the "administrative" link state on the host. From my experience when
logical networks are attached via the Setup Networks dialog, it does go
up, although I haven't tried without an IP address. Also, it's worth
trying to see if the actual networking works even if the NIC shows as
down, or to ifup the NIC manually if it doesn't.

> --- ifcfg-dummy0 ---
> DEVICE=dummy0
> ONBOOT=yes
> TYPE=Ethernet
> DELAY=0
> BOOTPROTO=none
> NM_CONTROLLED=no
> STP=no
> --- ifcfg-dummy0 ---
> 
> My "ifcfg-dummy1" is identical, except of course it has "DEVICE=dummy1"
> in it.  The interfaces do come up on the host, but as I said, in "Setup
> Host Networks" they have a red dot instead of a green one.  Perhaps I do
> need to assign an IP?  I can maybe assign a "dummy" one (i.e., one that
> I would never use)?
> 
> -Alan
> _______________________________________________
> Users mailing list
> Users at ovirt.org
> http://lists.ovirt.org/mailman/listinfo/users