Re: [libvirt] 802.1q vlan-tagging support for libvirt
On Tue, 2009-04-07 at 18:39 -0300, Klaus Heinrich Kiwi wrote:
I was thinking about the semantics I described above. It ultimately
means that we'll have a bridge for each VLAN tag that crosses the trunk
interface. So for example if guests A, B and C are all associated with
VLAN ID 20, then:
eth0 -> eth0.20 -> br0 -> [tap0, tap1, tap2]
(where tap[0-3] are associated with guests A, B, C respectively)
Yes, I think that's how it should work; it would also mean that you'd
first set up eth0 as a separate interface, and new bridge/vlan interface
combos afterwards. AFAIK, for the bridge, only bootproto=none would make
sense.
The things that concerns me the most are:
1) How scalable this really is
I don't know either ... we'll find out ;)
2) The semantics are really different from how physical,
802.1q-enabled
switches would work.
Because (2) really creates new switches for each new VLAN tag, I wonder
how management would be different from what we have today with physical
switches (i.e., defining a port with a VLAN ID, assigning that port to a
physical machine) - unless we hide it behind libvirt somehow.
The reason we are creating all those bridges isn't the VLAN's - it's
that we want to share the same physical interface amongst several
guests. And I don't know of another way to do that.
Are there other options? Since a tagged interface like eth0.20 is
kind
of a virtual interface itself, would it be appropriate to use those
directly?
You can use it directly, I just don't know how else you would share it
amongst VM's without a bridge.
David