[ovs-discuss] OVN: availability zones concept

Han Zhou zhouhan at gmail.com
Wed Mar 6 05:39:37 UTC 2019


On Tue, Mar 5, 2019 at 7:24 PM Ben Pfaff <blp at ovn.org> wrote:
> What's the effective difference between an OVN deployment with 3 zones,
> and a collection of 3 OVN deployments?  Is it simply that the 3-zone
> deployment shares databases?  Is that a significant advantage?

Hi Ben, based on the discussions there are two cases:

For completely separated zones (no overlapping) v.s. separate OVN
deployments, the difference is that separate OVN deployments requires
some sort of federation at a higher layer, so that a single CMS can
operate multiple OVN deployments. Of course separate zones in same OVN
still requires changes in CMS to operate but the change may be smaller
in some cases.

For overlapping zones v.s. separate OVN deployments, the difference is
more obvious. Separate OVN deployments doesn't allow overlapping.
Overlapping zones allows sharing gateways between different groups of
hypervisors.

If the purpose is only reducing tunnel mesh size, I think it may be
better to avoid the zone concept but instead create tunnels (and bfd
sessions) on-demand, as discussed here:
https://mail.openvswitch.org/pipermail/ovs-discuss/2019-March/048281.html

Daniel or other folks please comment if there are other benefit of
creating zones.

Thanks,
Han


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