[openstack-dev] [Neutron] Campus Network Blueprint

Filipe Manco filipe.manco at gmail.com
Sun Jul 14 20:24:58 UTC 2013

Thank you for reading the BP and provide comments. My comments are  inline.

2013/7/12 Zang MingJie <zealot0630 at gmail.com>

> Hi Filipe:
> I disagree your ml2-external-port BP
> It is unsuitable to connect multiple l2 networks directly, there may
> be ip conflict, dhcp conflict and other problems. although neutron
> dhcp agent won't respond dhcp request from unknown source, an external
> dhcp may respond vm dhcp request.

About conflicts, why is that a problem? Users are suposed to control both
the virtual and physical environment. If I put a DHCP server on a VM there
may be DHCP conflicts as well. L3 services may then be extended to support
external ports. But I'm not considering that for now.

> If we move an external port form a
> network to another network, how can we ensure that the arp cache is
> cleared.

About the ARP tables there are two cases: VMs and physical hosts, and
network equipment. About the first ones there's nothing we can or should
do. The same happens if I move my laptop from a network to another. About
the physical equipment if it is necesary to cleanup ARP tables to speed the
process, code implementing the equipment managment can take care of that.

> And it will aslo make l2-population bp (
> https://blueprints.launchpad.net/quantum/+spec/l2-population ) more
> difficault. Our l2 forwarding works better if the device knows the
> whole topology of the network, but the external part is totally
> unknown.

About your l2-population BP there will be no changes unless you want,
because it isn't expected that all the network types implement external
ports. If GRE or VXLAN (I think those are the ones supported by your BP)
don't implement external ports you don't have to do anything as far as I
can see.

> So, I suggest a layer-3 solution, where the out world connects to vms
> via l3 agent.
Finally I agree L3 will fit almost allways, but there are cases where L2 is
required. Currently one solution is to tunnel L2 over L3 from an external
machine to a VM connected to the virtual network. But my purpose is that
Neutron can provide that out of the box.

> Thank you for sharing the idea
> Regards

> OpenStack-dev mailing list
> OpenStack-dev at lists.openstack.org
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