On 11/11/2012 10:07 PM, Dan Kenigsberg wrote:
Hi,

Nowadays, when vdsm receives the setupNetowrk verb, it mangles
/etc/sysconfig/network-scripts/ifcfg-* files and restarts the network
service, so they are read by the responsible SysV service.

This is very much Fedora-oriented, and not up with the new themes
in Linux network configuration. Since we want oVirt and Vdsm to be
distribution agnostic, and support new features, we have to change.

setupNetwork is responsible for two different things:
(1) configure the host networking interfaces, and
(2) create virtual networks for guests and connect the to the world over (1).

Functionality (2) is provided by building Linux software bridges, and
vlan devices. I'd like to explore moving it to Open vSwitch, which would
As far as I know, ovs also supports bond. Even though it doesn't have as many modes as what Linux bonding has, it supports load balancing and fail-over at least. For vlan, we could make the nic port as trunk port and use libvirt's 'portgroup' feature to create an access or trunk port for vif. Then it could replace Linux vlan configuration.

enable a host of functionalities that we currently lack (e.g.
tunneling). One thing that worries me is the need to reimplement our
config snapshot/recovery on ovs's database.
Undo the ovs command could restore the ovs database to the state before the new configuration call. This could help in some cases. If we can separate vm network from management network, it should not be a big problem.

As far as I know, ovs is unable to maintain host level parameters of
interfaces (e.g. eth0's IPv4 address), so we need another
tool for functionality (1): either speak to NetworkManager directly, or
to use NetCF, via its libvirt virInterface* wrapper.
IMHO, ip address is not useful for pure vm network. We can leave the network address configuration of management network to deployment. So ovs can cover all typical network configurations. I think we don't need to wait for NetworkManager is ready to consume via libvirt virInterface. We could have multiple network management drivers in vdsm. And part of openvswitch support code is also useful to integrate quantum
into oVirt.


I have minor worries about NetCF's breadth of testing and usage; I know
it is intended to be cross-platform, but unlike ovs, I am not aware of a
wide Debian usage thereof. On the other hand, its API is ready for vdsm's
usage for quite a while.

NetworkManager has become ubiquitous, and we'd better integrate with it
better than our current setting of NM_CONTROLLED=no. But as DPB tells
us,
https://lists.fedorahosted.org/pipermail/vdsm-devel/2012-November/001677.html
we'd better offload integration with NM to libvirt.

We would like to take Network configuration in VDSM to the next level
and make it distribution agnostic in addition for setting the
infrastructure for more advanced features to be used going forward.
The path we think of taking is to integrate with OVS and for feature
completeness use NetCF, via its libvirt virInterface* wrapper. Any
comments or feedback on this proposal is welcomed.

Thanks to the oVirt net team members who's input has helped writing this
email.

Dan.


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